Merge pull request 'Android touch model, phases 2-4: swipe to queue, and the other three lists' (#201) from 63-touch-model-phase-2 into main

Plan 019 phases 3 and 4, which finish #63. The queue panel and both
playlist detail views get tap-to-play and hold-to-select; the playlist
views get swipe-to-queue as well.

Phase 3 was not the pure wiring the plan expected, in two places.

A tap on a queue row plays that position. Copying track-list's tap --
which sets the queue to the list the row is in -- would rebuild the
queue from the queue, discarding its source, its shuffle order and
anything inserted by hand. It reads as a no-op and is not one.

And the queue panel has no swipe, deliberately. A right swipe means add
to the queue everywhere else it exists, and a queue row is already in
the queue; the only thing it could mean there is remove, which is the
same gesture with the opposite effect one screen away. Removing a queue
row is on the row, on its sheet since #60, and now on its selection
bar. The assertion is that its rows do not opt in.

The reveal became utils/swipe-to-queue.ts rather than being copied into
three lists, keyed on a data-swipe attribute so one stylesheet carries
the touch-action half of the device fix to rows that are called two
different things.

Phase 4 was already true and is now asserted: a claimed tap has its
click swallowed, so an explore-link inside a row never sees one and
tap-to-play wins with no rule of its own. Its test was vacuous when
written -- the tap helper sent no click, so there was nothing to
swallow -- which also weakened phase 1's. It sends one now.

Escape leaves selection mode, from selection-bar rather than from each
of the four hosts, since that element exists only while the mode does.
The platform's back gesture deliberately does not reach it: the shell
owns the history stack and four lists reaching for history is four
stacks. That is #200.

Verified on the reference phone: a queue row taps to its own index and
refuses a swipe, a playlist row queues on a swipe and plays its
playlist on a tap, and a hold raises the bar without the menu.

Closes #63

.gitea/workflows/android-apk.yml

@@ -139,6 +139,23 @@ jobs:
             echo "skip=true" >> "$GITHUB_OUTPUT"
             exit 0
           fi
+
+          # Nor is a prerelease, and this trigger is `v*`, which matches
+          # `v0.4.0-beta.1`.  Two reasons it is worst here.  The APK goes
+          # to the *generic* registry, which is readable without
+          # credentials so Obtainium can poll a plain URL — a beta would
+          # be offered to every device on it.  And the versionCode maths
+          # below splits on dots and would read "1" out of "0-beta",
+          # producing a code that is wrong rather than a build that
+          # fails: Android orders releases by that integer and refuses
+          # anything not greater than what is installed.
+          case "$v" in
+            *-*)
+              echo "v$v is a prerelease; not publishing an APK for it"
+              echo "skip=true" >> "$GITHUB_OUTPUT"
+              exit 0
+              ;;
+          esac
           echo "skip=false" >> "$GITHUB_OUTPUT"
 
           # Android orders releases by an integer and refuses anything

.gitea/workflows/arch-package.yml

@@ -72,6 +72,22 @@ jobs:
             exit 0
           fi
 
+          # A prerelease is not a shipment either, and this trigger is
+          # `v*` — which matches `v0.4.0-beta.1`.  Nothing produces one
+          # today; the guard is here because the thing that would is
+          # semantic-release's `prerelease: true` channel, a one-line
+          # change in .releaserc.yml whose blast radius is four public
+          # package channels.  Same argument as release.yml's
+          # `chore(release):` guard: cheap, against something a future
+          # edit turns on somewhere else entirely.
+          case "$v" in
+            *-*)
+              echo "$v is a prerelease; not packaging it for pacman"
+              echo "skip=true" >> "$GITHUB_OUTPUT"
+              exit 0
+              ;;
+          esac
+
           echo "skip=false" >> "$GITHUB_OUTPUT"
           echo "tag=$v"     >> "$GITHUB_OUTPUT"
           echo "building $v"

.gitea/workflows/desktop-assets.yml

@@ -95,6 +95,19 @@ jobs:
             exit 0
           fi
 
+          # Nor is a prerelease, and this trigger is `v*`, which matches
+          # `v0.4.0-beta.1`.  The mildest of the four — assets attach to
+          # the prerelease's own Gitea release and no package manager
+          # reads them — but four workflows sharing one trigger should
+          # share one answer about what a shipment is.
+          case "$v" in
+            *-*)
+              echo "$v is a prerelease; not attaching desktop assets"
+              echo "skip=true" >> "$GITHUB_OUTPUT"
+              exit 0
+              ;;
+          esac
+
           echo "skip=false"   >> "$GITHUB_OUTPUT"
           echo "tag=$v"       >> "$GITHUB_OUTPUT"
           echo "version=${v#v}" >> "$GITHUB_OUTPUT"

.gitea/workflows/homebrew-formula.yml

@@ -56,6 +56,18 @@ jobs:
             echo "skip=true" >> "$GITHUB_OUTPUT"
             exit 0
           fi
+
+          # Nor is a prerelease, and this trigger is `v*`, which matches
+          # `v0.4.0-beta.1`.  It matters most here of the four: the tap
+          # is public, and `brew upgrade` would offer a beta to everyone
+          # on it.
+          case "$VERSION" in
+            *-*)
+              echo "$TAG is a prerelease; not syncing it to a public tap"
+              echo "skip=true" >> "$GITHUB_OUTPUT"
+              exit 0
+              ;;
+          esac
           echo "skip=false" >> "$GITHUB_OUTPUT"
 
           TARBALL="${SOURCE_TARBALL_BASE}/${TAG}.tar.gz"

.gitea/workflows/release.yml

@@ -1,11 +1,36 @@
 name: Release
 
 # The sixth workflow, and the one that decides whether the other three
-# run at all.  On every push to main it reads the Conventional Commits
-# since the last tag, and if any of them is releasable it writes the
-# changelog, pushes the tag, and creates the Gitea release whose body is
-# that changelog section.  The publishing workflows are keyed on `v*`, so
-# the tag push is what starts them.
+# run at all.  It reads the Conventional Commits since the last tag, and
+# if any of them is releasable it writes the changelog, pushes the tag,
+# and creates the Gitea release whose body is that changelog section.
+# The publishing workflows are keyed on `v*`, so the tag push is what
+# starts them.
+#
+# **It is triggered by hand, and there is deliberately no `push`
+# trigger.**  There was one, on `main`, which made the trigger "a PR was
+# merged" and nothing else: eight releases in twenty-two hours
+# (v0.0.1 -> v0.3.1) for one session's work, each fanning out to four
+# publishers on a runner with capacity 1, so ~40 packaging jobs shipped
+# three issues and ordinary PR CI queued behind them.  A version per
+# merged PR is a version per unit of *work*, not per *shipment*, and
+# pacman, Homebrew and Obtainium see every one.
+#
+# Nothing else had to change to batch them: semantic-release already
+# reads every commit since the last tag, so five fixes and two feats
+# become one minor release with all seven in the notes.  Release
+# frequency was only ever how often this file fired.
+#
+# This is the rule `index-artifact.yml` states and is the other instance
+# of: **a job that mutates state which cannot be rebuilt in ten minutes
+# is triggered deliberately, not by a push.**  A release here is a tag,
+# a Gitea release, an Arch package, a Homebrew formula, a signed APK and
+# desktop assets — and an Android version going backwards costs the user
+# their library (docs/android-release.md).
+#
+# A schedule was considered and rejected: a cron batches without anyone
+# having to remember, but it puts the decision back on a timer, which is
+# the thing being removed.
 #
 # **Why the tag is pushed with PACKAGE_TOKEN and not the Actions token.**
 # Gitea, like GitHub, does not start a workflow from a ref pushed by a
@@ -19,9 +44,12 @@ name: Release
 # instead.
 
 on:
-  push:
-    branches: [main]
   workflow_dispatch:
+    inputs:
+      dry_run:
+        description: "Report what would be released and stop"
+        required: false
+        default: "false"
 
 # Cutting a tag is not a thing to cancel halfway: a superseded run must
 # finish, not be killed between `git push --tags` and the release POST.
@@ -163,14 +191,32 @@ jobs:
       # been right, the tag would have been right, every job would have
       # been green, and the release body would have been empty.  Check the
       # notes, not the exit code, before moving any of these.
+      # The point of a manual trigger is deliberateness, and deliberate
+      # means being able to look before pulling the lever.  `--dry-run`
+      # reports the version and the notes and writes nothing: no tag, no
+      # release, no publishers.  `make release-dry` is the same answer
+      # locally; this is it from the runner, against the same commit and
+      # the same tag history, which is what actually decides.
       - name: Run semantic-release
         if: steps.guard.outputs.skip == 'false'
         working-directory: /src
+        env:
+          DRY_RUN: ${{ inputs.dry_run }}
         run: |
           set -eu
           git config user.name  "yellowjacket-ci"
           git config user.email "yj@yellowjacket.app"
 
+          # Anything but a literal "true" releases for real.  A typo in a
+          # dispatch box must not silently turn a shipment into a no-op
+          # that reports success — the failure worth avoiding is the one
+          # where nothing happens and the run is green.
+          dry=""
+          if [ "${DRY_RUN:-false}" = "true" ]; then
+            echo "DRY RUN — no tag will be pushed and no release created"
+            dry="--dry-run"
+          fi
+
           npx --yes \
             -p semantic-release@25 \
             -p @semantic-release/commit-analyzer@13 \
@@ -178,5 +224,5 @@ jobs:
             -p @semantic-release/changelog@7 \
             -p @semantic-release/exec@7 \
             -p conventional-changelog-conventionalcommits@9 \
-            semantic-release \
+            semantic-release $dry \
               --repository-url "https://x-access-token:${PACKAGE_TOKEN}@${SERVER_URL#https://}/${REPO}.git"

.gitea/workflows/unclaim.yml

@@ -0,0 +1,107 @@
+name: Unclaim
+
+# A `Closes #N` footer in a commit body closes the issue on merge — and
+# leaves `Status/In Progress` on it, because Gitea's auto-close touches
+# state and nothing else.  So #100 was closed and simultaneously marked
+# as being actively worked on, and `scripts/issue.sh close` (which does
+# drop the label) is exactly the thing the footer exists to avoid
+# calling.
+#
+# **This hooks the close, not the merge.**  Stripping the label in the
+# PR would work and would be a per-PR habit; habits are what the footer
+# removed.  `issues: [closed]` covers every path an issue can close by —
+# the footer on merge, `issue.sh close`, someone clicking Close in the
+# web UI — and asks nothing of anyone at any of them.
+#
+# **Reopening deliberately does not restore it.**  Reopening says the
+# work was not finished, not that somebody is at a keyboard doing it
+# now; the claim gets re-made by whoever picks it up.
+#
+# **This is not instant, and should not be described as it.**  The
+# runner has capacity 1 and is shared with an index build that can hold
+# it for three hours, so a label tweak can queue behind one. Stale for
+# an afternoon beats stale forever, which is what it was.
+#
+# The audit that answers "is this still firing" stays in CLAUDE.md and
+# is one command:
+#
+#   ./scripts/issue.sh list --state closed --label "Status/In Progress"
+#
+# A workflow that silently stops working is the failure mode this whole
+# area has already produced once.
+
+on:
+  issues:
+    types: [closed]
+
+jobs:
+  unclaim:
+    runs-on: ubuntu-latest
+    container:
+      image: ubuntu:24.04
+
+    steps:
+      - name: Drop the claim label
+        # **Inside a container the act runner selects `sh`, not bash**, so
+        # `set -o pipefail` fails the job on its second line with "Illegal
+        # option" and the step never reaches the API.  `homebrew-formula.yml`
+        # carries the same `set -euo pipefail` without trouble because it
+        # runs with **no container**, on the host image where bash is the
+        # default — so "another workflow does it" is not evidence here.
+        shell: bash
+        env:
+          # The automatic Actions token, as release.yml uses for the
+          # floor tag.  It needs no more than write access to this repo.
+          TOKEN: ${{ secrets.GITEA_TOKEN }}
+          API: ${{ github.server_url }}/api/v1/repos/${{ github.repository }}
+          ISSUE: ${{ github.event.issue.number }}
+        run: |
+          set -euo pipefail
+
+          # `ca-certificates` is named because `--no-install-recommends`
+          # skips it, and `ubuntu:24.04` ships no CA bundle of its own —
+          # so curl comes up unable to verify TLS against our own Gitea
+          # and fails with "error setting certificate file" (exit 77).
+          # Every other containerised workflow here spells it out for the
+          # same reason; this one did not, and cost a release cycle.
+          apt-get update -qq
+          apt-get install -y -qq --no-install-recommends \
+            ca-certificates curl jq >/dev/null
+
+          label_id=$(
+            curl -sSf -H "Authorization: token $TOKEN" "$API/labels?limit=100" |
+              jq -r '.[] | select(.name == "Status/In Progress") | .id'
+          )
+
+          # The label not existing is a repo somebody reorganised, not a
+          # failure of this run — say so and stop, rather than failing a
+          # job on every close from then on.
+          if [ -z "$label_id" ]; then
+            echo "unclaim: no 'Status/In Progress' label in this repo; nothing to do"
+            exit 0
+          fi
+
+          # DELETE is idempotent here: an issue that never carried the
+          # label answers the same as one that did, which is what makes
+          # this safe to run on *every* close rather than only the ones
+          # that were claimed.
+          # The body is captured, not discarded, so a refusal is
+          # diagnosable from this log alone.  Whether the automatic
+          # token carries issue-write scope is still unproven, and
+          # "DELETE returned 403" without Gitea's own sentence costs
+          # another merge to find out which of the two it is.
+          body=$(mktemp)
+          code=$(
+            curl -sS -o "$body" -w '%{http_code}' -X DELETE \
+              -H "Authorization: token $TOKEN" \
+              "$API/issues/$ISSUE/labels/$label_id"
+          )
+
+          case "$code" in
+            204) echo "unclaim: #$ISSUE is closed and unclaimed" ;;
+            *)
+              echo "unclaim: DELETE returned $code for #$ISSUE" >&2
+              cat "$body" >&2
+              exit 1
+              ;;
+          esac

.gitignore

@@ -88,3 +88,8 @@ build/android/overlay.json
 # Written by @semantic-release/changelog purely to carry the release notes
 # into scripts/gitea-release.sh; the release page is the changelog.
 .release-notes.md
+
+# Agent session log: local scratch, not repo memory (that is CLAUDE.md
+# and .planning/). Written by the scheduled backlog runs.
+.pi/journal.md
+.pi/schedule-prompts.json

.pi/journal.md

@@ -1,118 +0,0 @@
-# Work log
-
-Temporal memory: what happened and what's next. Structure lives in
-`CLAUDE.md`, operational instructions in `.pi/skills/yellowjacket-dev/`,
-measured discoveries in `.planning/NOTES.md`. Don't duplicate those here.
-
-## Current state
-
-Plan 005 (agent development harness) is **complete — all seven
-phases**. Everything from phase 1 onward is still **uncommitted**: one
-large but coherent working-tree diff, nothing pushed.
-
-All four tiers verified green from a cold, cleaned state:
-`make ui-test` 313 passed, `make lint` 0 issues × 3 configurations,
-`make test` green × 3 passes, `make e2e` 19 passed. Both CI jobs
-verified green in a bare `ubuntu:24.04` container, including 19/19 on
-WebKit.
-
-**Committed and pushed** as `5ca6cad` (the harness) + `ccacd67` (a CI
-fix), and **green on the real runner**: job `check` ~4 min, job `e2e`
-~3 min with 19/19 chromium *and* 19/19 webkit. One commit rather than
-seven because the working tree was the end state, not per-phase
-snapshots — `Makefile`, `CLAUDE.md` and `lefthook.yml` are touched by
-nearly every phase, so a split would have been fabricated history.
-
-Still unverified, because no run has failed yet: the
-`actions/upload-artifact` step (`continue-on-error`, so it cannot mask
-a real failure) and whether pnpm honours `npm_config_store_dir` for
-store caching. Worth checking the next time a spec legitimately fails.
-
-- [ ] `gitea_ci`'s `job_logs` returns 404 on Gitea 1.27.1 — the endpoint
-      is not exposed. Logs come from the VPS instead: `zstdcat` the file
-      under `gitea/actions_log/<owner>/<repo>/<xx>/<task_id>.log.zst`,
-      and note `zstdcat` is not in the gitea container, so
-      `docker cp` it out first. Job status is `action_run_job.status`
-      (1 success, 2 failure, 4 skipped, 5 waiting, 6 running).
-      Probably belongs in the `gitea` skill, not here.
-
-Open items deliberately not fixed: WAV tags are write-only
-(`TestWAVTagsAreNotReadableYet`), `themeStore.loadFromBackend`'s failure
-handler cannot recover, `backend/playlist` has no CRUD suite.
-
-## Log
-
-### 2026-08-11 — cold skill run, then phase 7 (CI)
-
-- **Followed the skill cold first**, as the last session asked. It
-  works: app up from a wiped `.dev/`, an undocumented flow driven
-  (queue panel + shuffle, asserted on `QueueModeChanged`), stopped —
-  ~1 minute, no dead ends. One real config bug: `outputDir` in
-  `.playwright/cli.config.json` resolves against **cwd**, not the
-  config file's directory (only `initScript` does that), so snapshots
-  were landing above the repo and a *stale* one from the previous
-  session answered `ls -t` instead. That cost a DOM walk to disprove a
-  regression that did not exist. Four smaller doc gaps fixed
-  (`sandbox-seed` already runs `testdata`; `ui-setup`/`e2e-setup` were
-  undocumented prerequisites; `snapshot` prints a path; `dev-stop`
-  leaves the browser open), plus `dev-headless.sh`'s own banner, which
-  was suggesting the bare `window.go` call its next paragraph warns
-  against.
-- **Built both CI jobs as container scripts before writing any YAML**,
-  then transcribed the YAML back out and re-ran it to prove the
-  transcription. Push-and-see is a bad loop on a self-hosted runner.
-- **It found a real bug immediately**: `make lint` omitted
-  `webkit2_41` on all three passes, so it was linting configurations
-  nothing builds. Invisible on Arch (which still ships
-  `webkit2gtk-4.0.pc`), fatal on Ubuntu 24.04. Tag sets now match
-  `make test`.
-- **Both open decisions settled by measurement**: ALSA `null` PCM for
-  audio (no daemon; the elapsed clock really advances), dead-address
-  stub for the explore artifact (and setting it for the *app* run, not
-  just seeding, is worth 8x on suite wall clock). **WebKit is a
-  required step** — it had never been run anywhere, so one throwaway
-  container run replaced a coin flip with 19/19 at +11 s.
-
-### 2026-08-10 — phase 6, pi affordances
-
-- Added `.pi/skills/yellowjacket-dev/` as a directory rather than a flat
-  file: only the description is always in context, so `SKILL.md` stays
-  short enough that reading it whole is never a decision, and the deeper
-  material sits in `references/{harness,fixtures,ui-tier,schema-change}.md`.
-- Settled the CLAUDE.md-vs-skill split **grammatically, not topically**,
-  because a topical split is what rots — every new fact gets two
-  plausible homes. Three docs, three tenses: NOTES.md is past
-  (measured, dated, append-only), CLAUDE.md is present (what the system
-  is), the skill is imperative (what to run). A new paragraph's tense
-  decides where it goes.
-- The five gotchas (binding timeouts, first-run wizard, `pkill -f`,
-  seeds-by-running, WebKit-is-CI-only) went **inline in SKILL.md**, not
-  into a reference: you need them before the failure, not after.
-- Trimmed CLAUDE.md's "Fixtures and the headless harness" section by
-  about half — the command sequences and gotchas it was carrying are now
-  the skill's, and leaving both would have created exactly the duplicate
-  description this repo has a standing rule against.
-- Added `make skill-check` / `scripts/skill-check.sh` + a pre-commit
-  hook: every command in `.pi/**/*.md` must be a real `make` target, so
-  the Makefile stays the source of truth for invocation and a renamed
-  target fails a commit instead of misleading an agent later. Verified
-  it fails (it caught its own not-yet-created target) and passes.
-- Added the `/e2e` prompt template: promoting a hand-driven
-  `playwright-cli` session into a spec is a transcription with four
-  fixed substitutions (refs → testids, sleeps → `waitForEvent`, raw
-  `window.go` → `callBinding`, short fixture → `LONG_TRACK`), plus three
-  runs — pass, pass again, pass after a DB restore — because the usual
-  failure is a spec depending on state the hand-driving left behind.
-- One shell trap: under `set -euo pipefail`, `x="$(make -pqRr | …)"`
-  fails the whole assignment, because `make -q` exits non-zero when a
-  target is out of date and `pipefail` propagates it.
-
-### Earlier
-
-Phases 1–5 of plan 005: fixture generator and manifest, headless launch
-and seeds, the event bridge + `data-testid` pass + `backend/testctl` +
-`e2e/`, the Vitest component tier + `make bindings-check`, and the
-`events.Emit` wrapper with its in-process service-event tests. Recaps
-and the five "verified end to end" blocks are in
-`.planning/plans/active/005-agent-development-harness.md`; the lessons
-are in `.planning/NOTES.md`.

.pi/prompts/next-issue.md

@@ -0,0 +1,142 @@
+---
+description: Take on the next actionable backlog issue end to end, and stop
+---
+Take on exactly one issue from the YellowJacket backlog, end to end, and stop.
+
+Repo: yonlu/yellowjacket at https://git.ljones.me — API base
+https://git.ljones.me/api/v1/repos/yonlu/yellowjacket, auth with
+`-H "Authorization: token $GITEA_TOKEN"`. Default branch is `main`.
+
+## 1. Orient before you pick
+
+Read, in this order: `CLAUDE.md` (the architecture and the reasons behind
+it), `.pi/journal.md` (what happened last), `.planning/NOTES.md` (what was
+already considered and rejected), and `.planning/plans/active/`. Do not skip
+this because the issue looks small — most of this codebase's traps are
+written down in exactly one of those four places, and the ones that bite are
+the ones you didn't read.
+
+## 2. Pick the issue
+
+List open issues. Choose the single highest-value one that is *actionable
+right now*:
+
+- Order by `Priority/Critical` → `High` → `Medium` → `Low`. Within a tier,
+  prefer `Reviewed/Confirmed`, then `Kind/Bug` over `Kind/Enhancement` over
+  `Kind/Feature`.
+- Consult issue #73 (the roadmap) — if it sequences the candidates, that
+  ordering wins over the label ordering.
+- **Skip** anything labelled `Status/Blocked`, `Status/In Progress`,
+  `Status/Abandoned`, `Reviewed/Won't Fix`, `Reviewed/Duplicate`,
+  `Reviewed/Invalid`, or already carrying an open PR.
+- **Skip anything someone else is already on.** The label is not the only
+  claim, because a concurrent session may not have applied it — several pi
+  sessions run against this repo from separate worktrees under
+  `~/.paseo/worktrees/`. Run `git ls-remote --heads origin` and skip any
+  issue whose number or slug matches an existing branch (`60-…`,
+  `fix/<slug>`). A duplicated fix costs more than a skipped issue.
+- **Skip** anything that cannot be verified without hardware you do not
+  have: physical-device Android behaviour (audio output, on-device file
+  writes, real gesture input). A browser at 424px is not a phone — see the
+  Chrome 113 section of `CLAUDE.md`.
+- **Skip** intermittent-failure issues unless you can reproduce the failure
+  on demand within a few minutes. Chasing a 1-in-3 flake is an unbounded
+  task and does not belong in a scheduled run.
+- If nothing qualifies, say so, do nothing, and stop. An empty run is a
+  correct outcome.
+
+## 3. Claim it
+
+Add `Status/In Progress` to the issue and comment that you are picking it
+up. Then branch:
+
+```
+git fetch origin && git checkout -b <type>/<short-slug> origin/main
+```
+
+`<type>` matches the issue's `Kind` (`fix/`, `feat/`, `refactor/`, `test/`,
+`docs/`, `ci/`). Branch from `origin/main`, never by checking out `main`
+itself — this repo is worked from several git worktrees at once and `main`
+is checked out in one of them, so `git checkout main` fails outright.
+
+## 4. Do the work
+
+Fix the issue that was reported and nothing else. Match the surrounding
+code's style. Follow the constraints in `CLAUDE.md` rather than reasoning
+from first principles — where it explains why something is shaped the way it
+is, that shape is load-bearing and there is usually a test pinning it.
+
+**Anything else you discover becomes a new issue, not a bigger diff.** File
+it with the right `Area/`, `Kind/`, `Priority/` labels, describe the
+symptom before the theory, and link it from your PR. Scope creep is the
+failure mode this instruction exists to prevent.
+
+If the work turns out to be materially larger than the issue implied, stop:
+comment on the issue with what you found and what it would actually take,
+remove `Status/In Progress`, push nothing, and end the run.
+
+## 5. Verify — the right tier, not the cheapest one
+
+Run `make generate` if you touched `.sql` or `.templ`, and `make bindings`
+if you changed a bound Go signature. Then run what the change actually
+demands:
+
+- Go change → `make lint` and `make test` (both cover all three build
+  configurations).
+- Frontend component or store → `make ui-test`.
+- User-visible flow → `make e2e` against `make dev-headless`. **Check the
+  port first**: `ss -ltn | grep 34115`. If it is occupied, another worktree
+  is already running the app — do not start a second one and do not run
+  `make e2e`. Attaching to someone else's build produces a green result
+  about code that is not yours, which is worse than no result. Either
+  choose an issue that does not need this tier, or stop and say why.
+- Anything cosmetic or layout-related → look at a screenshot. Several bugs
+  in this repo's history were invisible to every assertion and obvious in an
+  image.
+
+A tier you skipped is a claim you did not check. If a tier fails for reasons
+unrelated to your change, say so explicitly rather than quietly moving on.
+
+## 6. Keep the documentation true
+
+If you changed structure, behaviour, or a constraint, update `CLAUDE.md` in
+the same commit. That file is this project's memory; a change that leaves it
+describing the old shape is worse than no change. Append a short entry to
+`.pi/journal.md` covering what you did, what you verified, and what you left
+open.
+
+## 7. Commit and open the PR
+
+Conventional Commits, imperative subject, ≤72 chars, scope optional. The
+body explains *why*. Push the branch — never push to `main`, never
+force-push.
+
+Open the PR:
+
+```
+curl -sS -X POST \
+  -H "Authorization: token $GITEA_TOKEN" \
+  -H "Content-Type: application/json" \
+  https://git.ljones.me/api/v1/repos/yonlu/yellowjacket/pulls \
+  -d '{"head":"<branch>","base":"main","title":"<subject>","body":"<body>"}'
+```
+
+The body states: what the issue was, what you changed and why, **which
+verification tiers you ran and their results**, anything you deliberately
+did not do, and `Closes #<n>`.
+
+Then wait for CI (`ci.yml`, jobs `check` and `e2e`) and report the result on
+the PR. If it fails, read the log — `gitea_ci`'s `job_logs` 404s on this
+Gitea build, so use
+`GET /api/v1/repos/yonlu/yellowjacket/actions/runs/<run>/jobs` for per-step
+status and `GET /api/v1/repos/yonlu/yellowjacket/actions/jobs/<id>/logs` for
+the log — and fix it. Two consecutive failed CI runs on the same cause: stop,
+comment what you know on the PR, and leave it for a human.
+
+**Do not merge.** Comment on the issue linking the PR, leave
+`Status/In Progress` on, and end the run.
+
+## Finally
+
+Report in three lines: which issue you took, what state it is in
+(PR open / CI green / stopped and why), and any issues you filed.

.pi/skills/yellowjacket-dev/SKILL.md

@@ -130,7 +130,13 @@ reference, because you need them *before* the failure, not after.
   what you otherwise get is `Property 'scroll' does not exist on type
   'CSSResult'` pointing at a line of prose, or every test in the suite
   failing to import. It went in after the trap cost a fourth session in
-  which its own warning had been read twice.
+  which its own warning had been read twice. **The same command carries
+  a second CSS check**: a nested rule whose selector starts with an
+  element name (`audio-player { … }` rather than `& audio-player { … }`)
+  is silently dropped by the device's Chrome 113 and by nothing else, so
+  every tier you can run renders it correctly. Run it after touching
+  `index.css` or any `css` literal; a rule directly inside a top-level
+  `@media` is not nested and is not flagged.
 - **A failing CI job's log is reachable even when `gitea_ci job_logs`
   says it is not.** That endpoint 404s on this Gitea build. The REST
   API answers, with the `GITEA_TOKEN` already in the environment:
@@ -195,6 +201,12 @@ Two rules about climbing:
 - **Do not write an e2e spec first.** Drive the flow by hand, then
   promote it with `/e2e`. Specs written blind assert on selectors that
   do not exist.
+- **Not every view has a nav item.** Since #25 the destinations are
+  configurable, Autotag is hidden by default and Downloads is absent
+  until a download client exists — so `getByTestId('nav-<view>')` waits
+  30 s for a locator that will never resolve. `navigateTo(page, view)`
+  (`e2e/support/fixtures.ts`) dispatches the app's own `navigate` event.
+  Click the nav item when the *nav* is what the spec is about.
 
 Before a commit, the gate is `make lint`, `make test`, `make ui-test`,
 `make bindings-check`, `make css-check` and — from `frontend/` —

.pi/skills/yellowjacket-dev/references/android-tier.md

@@ -8,13 +8,29 @@ This tier answers "does the phone build run", nothing else. It is not a
 spec tier, it does not run in CI, and the app is not a usable Android
 player yet (plan 015 says why, at length).
 
-## Three facts that make failure invisible
+## Two facts that make failure invisible
 
-**Go's stdout does not reach logcat.** An Android app's fd 1 and 2 go to
-`/dev/null`. Every `slog` line the app writes is discarded — including
-the one naming the error it is about to exit on. `setprop
-log.redirect-stdio true` does not help: it redirects the *Java*
-runtime's `System.out`, and the Go code is a c-shared native library.
+There were three. The first was that **Go's stdout does not reach
+logcat** — an Android app's fd 1 and 2 go to `/dev/null`, so every
+`slog` line the app wrote was discarded, including the one naming the
+error it was about to exit on. That is fixed (#160):
+`backend/androidlog` is a `slog.Handler` over `__android_log_write`,
+selected in `main()` by build tag, and the app's whole diagnostic
+stream now arrives under the `yellowjacket` tag, which `make
+android-logs` filters for.
+
+What remains true about it is the part that misleads: **`setprop
+log.redirect-stdio true` still does not help**, because it redirects
+the *Java* runtime's `System.out` and the Go code is a c-shared native
+library. Nothing that reaches logcat here does so through stdout, so
+anything printed with `fmt.Println` is still lost. Log with `slog`.
+
+The tag is a fixed string rather than the application id, and that is
+load-bearing rather than tidy: the debug build carries
+`applicationIdSuffix ".dev"` so it can be installed beside the release
+app, and it is the only build whose WebView can be inspected — so a tag
+derived from the id would be filtered out on the one build anybody
+debugging this app is running.
 
 **`os.Exit` is a silent death.** `main()` ends several failure paths in
 `os.Exit(1)`. From Android's side that is a process that vanished:
@@ -34,7 +50,10 @@ the wrong question. `make android-smoke` asks the right one — is it the
 The tell, once you know it: `I/WailsBridge: Wails bridge initialized`
 followed immediately by a new pid doing the same thing. That means the
 native library loaded, the JNI bridge came up, Go's `main()` ran, and
-`main()` left. Work backwards through its `os.Exit(1)` paths.
+`main()` left. Work backwards through its `os.Exit(1)` paths — and
+since #160, **read the `E/yellowjacket` line above it first**, because
+every one of those paths logs the error before it exits. That line is
+what #52 spent months without.
 
 ## What to run
 
@@ -194,9 +213,13 @@ like the app's fault and none is:
 |---|---|---|
 | x86_64 | modernc's raw `lstat` vs seccomp | SIGSYS, syscall 6 |
 | arm64, translated | Go reads `ID_AA64ISAR0_EL1` | SIGILL |
-| arm64, real device | — | unverified, still |
+| arm64, real device | **runs** (2026-08-20) | — |
 
-**A physical arm64 device remains the only verification path.**
+**A physical arm64 device remains the only verification path**, and it
+has now been walked: a Light Phone III (TLP301, Android 14 / SDK 34,
+arm64-v8a, WebView Chrome 113 at 424x439). The app builds, installs,
+launches and stays up; `make android-smoke SECONDS=60` passes on it.
+What that run *found* is the lifecycle fault below.
 
 ### What was fixed to get here
 
@@ -210,6 +233,11 @@ no-op. `backend/system` gained no import of the Wails application
 package, which matters for the same reason `backend/events` is split by
 the `indexbuild` tag.
 
+**And `main()` is now latched to one run per process** (#52). That is
+the second `os.Exit(1)` in this file's history and it had the same
+signature as the first, which is the argument for #160: both were named
+exactly by an `slog` line that went to `/dev/null`.
+
 ### What is still not done
 
 The shell is still a desktop shell, and the x86_64 half of the APK is
@@ -249,10 +277,25 @@ one.
 `build/android/Taskfile.yml` ships more than the Makefile wraps, and
 they are the right thing to reach for when you want something one-off:
 
+> **These four were unsafe until #159 and are now the way in.** All of
+> them began with `adb uninstall {{.APP_ID}}`, where `APP_ID` defaulted
+> to `app.yellowjacket` — the **release** id — while `run` and
+> `run:device` build the **debug** variant, whose id is
+> `app.yellowjacket.dev`. So they uninstalled the user's app, taking
+> the library with it, installed a different package, and then failed
+> to launch the one they had removed.
+>
+> They share `scripts/android-deploy.sh` now, which **never**
+> uninstalls (`install -r`, and a changed signing certificate is
+> reported with the command rather than acted on), reads the package id
+> back out of the built APK, and refuses a target that is not the kind
+> the task names. There is nothing left to avoid; the manual sequence
+> below is kept because it is still the smallest thing that works.
+
 ```
 wails3 task android:run              # debug build + emulator install + launch
-wails3 task android:run:device       # same, first connected physical device
-wails3 task android:deploy-device    # production APK to a device
+wails3 task android:run:device       # debug build + install + launch on a phone
+wails3 task android:deploy-device    # release build, same
 wails3 task android:bundle:fat       # AAB, for a Play Store upload
 wails3 task android:studio           # open build/android/ in Android Studio
 wails3 task android:device:list
@@ -260,6 +303,16 @@ wails3 task android:logs:all
 wails3 task android:clean
 ```
 
+**`run` and `deploy-emulator` mean the emulator, and now say so to
+adb.** They used a bare `adb install`, which with exactly one device
+attached picks that device whatever it is — so with a phone plugged in
+and no emulator running, the task whose summary reads "in the Android
+Emulator" installed on the phone. They pass `--target emulator` and
+refuse with `make android-emulator` as the remedy.
+
+**`DEVICE_ID=<serial>` still names a device, and several attached
+devices is now an error rather than a silent pick of the first.**
+
 Two are deliberately **not** wrapped. `android:logs` greps logcat for
 `(Wails|yellowjacket)`, which catches the `WailsBridge` tag but misses
 the app's own process tag (`app.yellowjacket` — lowercase, so `Wails`
@@ -269,16 +322,51 @@ instead. And `ensure-emulator` boots whatever `-list-avds | tail -1`
 returns, with no pidfile and no boot wait, so it cannot be stopped or
 sequenced.
 
-## The identity is declared twice
+## The identity is read back from the APK
 
+It used to be **declared twice**, and that is what #159 was.
 `applicationId` in `build/android/app/build.gradle` is what Gradle
-installs. `APP_ID` in `build/android/Taskfile.yml` is what every
-adb-driven task uninstalls, launches and filters. **Nothing enforces
-that they agree**, and `ANDROID.md`'s advice to set `APP_ID` in
-`build/config.yml` does not work in beta.8 — `wails3 task` never reads
-that file (verified with `--dry`), and even when set it feeds only the
-adb commands, never Gradle. Change both or the official `run`/`deploy`
-tasks address a package that is not installed.
+installs; `APP_ID` in `build/android/Taskfile.yml` was what every
+adb-driven task uninstalled, launched and filtered, and nothing
+enforced that they agree. They did not: the debug buildType carries
+`applicationIdSuffix ".dev"`, so every task that assembles a debug APK
+addressed the release id. This file flagged the hazard for five phases
+and it cashed out twice — once as a wrong `am start`, once as an
+uninstall of the user's library.
+
+**`scripts/android-pkgid.sh` is the one answer now.** It prints the
+package id an APK declares (`aapt2 dump packagename`, falling back to
+`aapt dump badging`), and the deploy path installs and launches *that*.
+The APK is the authority because the task that installs it has just
+built it: whatever Gradle resolved the applicationId to, suffixes and
+flavours included, is in the file, and no default can disagree with it.
+An APK it cannot read is a hard failure, never a fallback to a written
+down default — guessing is the bug.
+
+**`APP_ID` survives as an assertion, not a setting**, and has no
+default. `wails3 task android:run APP_ID=app.yellowjacket` says "this
+build had better declare that id" and is refused, naming both, *before*
+anything is installed or a device is even chosen. It could never have
+been a setting: `ANDROID.md`'s advice to put it in `build/config.yml`
+does not work in beta.8 — `wails3 task` never reads that file (verified
+with `--dry`) — and even when set it fed only the adb commands, never
+Gradle.
+
+`scripts/android-emulator.sh` derives `PKG` the same way, from
+`bin/yellowjacket.apk` when one is built, so `make android-install`,
+`android-launch`, `android-logs` and `android-smoke` follow whichever
+variant is actually in `bin/`. `YJ_ANDROID_PKG` still overrides, and
+the old literal survives only for a tree with no APK built yet.
+
+**The uninstall is gone and is not coming back.** It existed to make
+the bare `install` on the next line work at all — without `-r` Android
+refuses an install over an existing package — so `install -r` removes
+the *reason* for it rather than merely removing it. What is left is the
+one case an uninstall really is the remedy, a changed signing
+certificate, and that is exactly the case where performing it silently
+costs the user their library. So it is named and not done, which is the
+answer `scripts/android-emulator.sh` had already reached for
+`make android-install`.
 
 Related, and it will bite once: the launcher activity is
 `com.wails.app.MainActivity` and the applicationId is
@@ -287,6 +375,27 @@ resolves the leading dot against the *applicationId* and fails with a
 class-not-found that reads like a broken build. Always the
 fully-qualified form.
 
+**`wails3 task android:run:device` is the way to put a debug build on a
+real device**, since #159. What #52 used, before it was safe, was the
+longer form, and it is still the smallest thing that works if you want
+no script between you and adb:
+
+```bash
+wails3 task android:build ARCH=arm64 && wails3 task android:assemble:apk
+adb install -r bin/yellowjacket.apk      # -r, never uninstall
+adb shell am start -n app.yellowjacket.dev/com.wails.app.MainActivity
+```
+
+The id in that last line is the one thing to keep an eye on by hand —
+`./scripts/android-pkgid.sh bin/yellowjacket.apk` is what the tasks ask,
+and it is a good habit before any `am start` written out in full.
+
+`YJ_ANDROID_PKG=app.yellowjacket.dev` still overrides what
+`scripts/android-emulator.sh` — and therefore `make android-smoke`,
+`android-logs`, `android-launch` — addresses, but it is rarely needed
+now: that default is read from `bin/yellowjacket.apk`, so it already
+follows whichever variant was built last.
+
 ## What only a device can answer
 
 The emulator cannot run this app (three separate reasons, none of them
@@ -311,6 +420,91 @@ system bars, the back gesture, focus and audio interruptions,
 permission dialogs, the keyboard — not about what the app draws. The
 drawing is what the other five tiers already cover.
 
+**The third such fault was the activity lifecycle** (#52), and it is
+the one to re-check after touching `main()`, `WailsBridge` or
+`MainActivity`. Android destroys and recreates an activity **without
+restarting the process**, and Wails' `nativeInit` — which
+`MainActivity.onCreate` calls — runs `go mainFunc()` every time. So
+Go's `main()` ran again on a live app, `app.Run()` refused (`a.starting`
+is still true behind Android's `select{}`), and the `os.Exit(1)` under
+it took the healthy first app down with it.
+
+### The lifecycle check, and how to trigger it on demand
+
+This is the regression guard for #52 on this tier, because no other
+tier runs `main()` on Android at all. The Go-side guard
+(`TestMainClaimsBeforeItDoesAnything`) catches work creeping above the
+latch; only the device catches the latch not working.
+
+**Trigger a relaunch with a configuration change the manifest does not
+declare.** `AndroidManifest.xml` lists
+`orientation|screenSize|keyboardHidden|uiMode`, so those are handled
+in-place and are *not* triggers. `fontScale` is not listed, and it is a
+one-liner:
+
+```bash
+adb shell settings put system font_scale 1.15   # restore the old value after
+```
+
+That is the same in-process destroy/recreate that "Don't keep
+activities", a locale change and a memory trim produce, but on demand.
+
+**"Don't keep activities" is the report's own lever and did not work on
+this device**: `settings put global always_finish_activities 1` reads
+back as `1`, `am set-always-finish-activities` does not exist on this
+build, and the activity was never finished on backgrounding. Do not
+spend an afternoon on it; use the config change.
+
+**The assertion is the pid, and the tell is two bridge inits in one.**
+
+```bash
+adb logcat -d | grep -E "Wails bridge initialized|has died|finishDrawing of relaunch"
+```
+
+Healthy is one pid appearing twice — the process surviving the
+recreation:
+
+```
+I/WailsBridge(28420): Wails bridge initialized
+I/WailsBridge(28420): Wails bridge initialized     <- same pid, recreated
+```
+
+Broken is that pair followed within a second by:
+
+```
+I/WindowManager: finishDrawing of relaunch: Window{...MainActivity} 603ms
+I/ActivityManager: Process app.yellowjacket.dev (pid 22956) has died: fg  TOP
+W/ActivityTaskManager: Force removing ActivityRecord{...}: app died, no saved state
+```
+
+Two things about reading that. **`has died: fg  TOP` is not a memory
+kill** — the system does not reclaim the foreground process, so this is
+the app leaving of its own accord. And there is **no crash record
+anywhere**: `logcat -b crash` is empty, no `AndroidRuntime`, no
+`libc: Fatal signal`, no tombstone. That is the `os.Exit` signature,
+and it is why "the system killed it" is the wrong first hypothesis.
+
+**Surviving is only half of it — check the recreated WebView is still
+wired to the running app.** A plausible-looking fix (making
+`WailsBridge.initialized` static, so the second `nativeInit` is skipped)
+keeps the process alive and silently breaks this, because `nativeInit`
+is also what re-points the JNI reference at the new bridge. Go would go
+on executing JavaScript against the destroyed activity's WebView: the
+app opens, renders, and never receives another backend event.
+
+Ask the page, after a relaunch and a resume:
+
+```bash
+make android-inspect
+make android-eval EXPR='(()=>{window.__probe=[];const o=window._wails.dispatchWailsEvent.bind(window._wails);window._wails.dispatchWailsEvent=(e)=>{window.__probe.push(e&&e.name);return o(e)};return "ok"})()'
+# background and foreground the app, then:
+make android-eval EXPR='JSON.stringify(window.__probe)'
+```
+
+A healthy build answers with events from the live services —
+`["IndexStatusChanged","JobsChanged","JobsChanged","android:storageAccess"]`.
+`[]` means the bridge reference is stale.
+
 ## Asking the device, not just looking at it
 
 A real phone can be inspected, and that turns this tier from "reported
@@ -340,6 +534,130 @@ Four things about it, each of which costs an hour if met cold:
   script. Plug in over USB for anything longer than a couple of probes.
 - **The socket name carries the pid**, which changes on every launch, so
   it is resolved rather than remembered.
+- **A reinstall resets the runtime permissions**, and the grant dialog
+  is a separate activity that takes focus — so the app is up, `am start`
+  reports "delivered to currently running top-most instance", and
+  `pidof` is empty because it never got to the foreground.
+  `dumpsys window | grep mCurrentFocus` naming
+  `GrantPermissionsActivity` is the tell. `adb shell pm grant
+  app.yellowjacket.dev android.permission.READ_MEDIA_AUDIO` (and
+  `POST_NOTIFICATIONS`) ahead of the launch skips it.
+
+### Getting the app into a state worth measuring
+
+A fresh install is **not** a neutral starting point, and three things
+about it will each cost you a measurement.
+
+**It downloads the real catalog.** `YJ_CORE_INDEX_URL` is stubbed in
+`dev-headless.sh` and in CI and is *real* here, so the app spends its
+first minutes fetching ~0.6 GB and `job-band` is **103px of a 439px
+screen** while it does. Every vertical number taken in that state is
+wrong -- one #51 measurement had the album art at 0px and it was
+entirely this.
+
+`__yj.call("explore.Service.StopIndexBuild", [])` stops it and returns
+cleanly. **It then starts again within seconds.** So stop it
+*immediately before* the measurement rather than once at the beginning,
+and check `jobs.Service.GetJobs` afterwards -- an empty array is the
+only proof. `jobs.Service.ClearFinishedJobs` tidies the finished rows
+that otherwise keep the band open.
+
+**A library added over the bridge does not dismiss the first-run
+wizard.** `library.Library.AddLibrary` works and scans, but the wizard
+checks for an existing library once, on mount, and its "Get Started"
+button gates on a directory chosen *in the wizard* -- so it stays up
+with a correctly disabled button over everything you are trying to
+measure. Nothing is broken; reload the page and it is gone. This reads
+exactly like a tap being swallowed, which is the expensive part.
+
+**Scoped storage decides where the music can be.** `/sdcard/Music/...`
+plus `pm grant <pkg> android.permission.READ_MEDIA_AUDIO` works and
+`AddLibrary` takes the plain path; a push into
+`/sdcard/Android/data/<pkg>/files/` looks like it worked and then is not
+there. Some builds additionally want
+`appops set <pkg> MANAGE_EXTERNAL_STORAGE allow`, and until they have it
+the app opens the *system* "All files access" screen on launch -- so
+`dumpsys window | grep mCurrentFocus` naming `com.android.settings` is
+that, not a crash.
+
+### A note on quoting `make android-eval`
+
+`EXPR='...'` is a single-quoted shell word, so anything with a quote or
+an apostrophe in it -- a file path like `Blazo, 49'ers - ...`, or a
+snippet containing a string literal -- breaks in a way that reads as a
+JavaScript error. Put the expression in a file and pass it positionally:
+
+```bash
+node ./scripts/android-eval.mjs "$(cat /tmp/probe.js)"
+```
+
+That is the same script `make android-eval` wraps, so nothing is lost.
+Two things worth knowing about it: it does **not** await a promise, so
+an async call has to park its result (`window.__r = ...`) and be read
+back in a second eval; and the shim from the section below is lost on
+every reload and every app restart, along with the devtools socket,
+whose name carries the pid.
+
+### Calling a binding on the device
+
+**The runtime call does not go over HTTP on Android**, and this is worth
+knowing before an hour is spent on it. The WebView cannot deliver a
+`fetch()` POST body to `shouldInterceptRequest`, so v3 routes runtime
+calls through the `addJavascriptInterface` bridge instead: the
+@wailsio/runtime installs a `customTransport` that calls
+`window.wails.invokeAsync(id, payload)` and receives the answer on
+`window._wailsAndroidCallback`. Two consequences:
+
+- **`.playwright/init-events.js` does not transfer to the device.** Its
+  outbound half hooks `fetch`, which sees nothing here, and its
+  `call()` posts to `/wails/runtime`, which answers
+  `Invalid runtime call: missing object value` — the interceptor got the
+  URL with no body. Its *inbound* half is still right, because
+  `dispatchWailsEvent` is the entry point in every mode.
+- **Hooking `fetch` from an eval is too late anyway**, on any platform:
+  the bundle captured its reference at module scope, so a wrapper
+  installed afterwards records nothing. That is why the harness is an
+  `initScript` and not a step in a spec.
+
+What works is to borrow the bridge, chaining the runtime's own callback
+so its pending calls still resolve:
+
+```js
+const pending = new Map();
+const prev = window._wailsAndroidCallback;
+window._wailsAndroidCallback = (id, response, error) => {
+  if (!pending.has(id)) return prev && prev(id, response, error);
+  const p = pending.get(id); pending.delete(id);
+  const env = JSON.parse(response || "{}");
+  return env.ok ? p.resolve(env.data ?? env.text) : p.reject(new Error(env.error));
+};
+window.__yj = { call(name, args) {
+  return new Promise((resolve, reject) => {
+    const id = "yj" + Math.random().toString(36).slice(2);
+    pending.set(id, { resolve, reject });
+    window.wails.invokeAsync(id, JSON.stringify({
+      object: 0, method: 0, windowName: "",
+      args: { "call-id": id, methodName: "yellowjacket/backend/" + name, args: args || [] },
+      clientId: window._wails.clientId,
+    }));
+  });
+} };
+```
+
+That turns the device into a tier that can be *driven* rather than only
+looked at — `__yj.call("player.Player.LoadFile", [path])` and
+`__yj.call("library.Library.AddLibrary", ["/sdcard/Music/..."])` are how
+#53 was measured. Names are the Go ones (`GetTracks`, not
+`GetAllTracks`); an unknown one comes back as a plain
+`unknown bound method name`, so a wrong guess is loud.
+
+**Getting audio onto the phone**: `adb push` into
+`/sdcard/Android/data/<pkg>/files/` looks like it works and then the
+files are not there — scoped storage. `/sdcard/Music/...` plus
+`pm grant … READ_MEDIA_AUDIO` does work, and `AddLibrary` takes the
+plain path. The generated fixtures are **~2 seconds** each, which is
+fine for a scan and useless for watching a seek bar, so synthesise a
+long one: `ffmpeg -f lavfi -i sine=frequency=440:duration=240`.
 
 **And the reason to bother: the phone is an engine, not a screen.** The
 first device here renders in **Chrome 113** at 424x439 CSS px. Every

.planning/audits/2026-08-11-ui/hands-on.md

@@ -13,7 +13,7 @@ reviews. Nothing was changed.
 
 Findings below are numbered `H-n` (hands-on) and cross-reference the
 static reports where they overlap. The reconciliation plan built from
-all four files is `.planning/plans/pending/007-ui-reconciliation.md`.
+all four files is `.planning/plans/completed/007-ui-reconciliation.md`.
 
 ---
 

.planning/plans/completed/012-api-call-audit.md

@@ -1,5 +1,7 @@
 # 012 — What we ask the network for, and what we already had
 
+> **Completed.** Findings 1, 2 and 4 shipped. Finding 3 — the bound-but-uncalled methods — is now **#86**.
+
 **Status:** all four findings fixed. Lint (3 configs), Go tests (3
 configs), `tsc` and 752 Vitest tests pass; **not driven against the
 real app**, so the numbers below are read off the code, not measured.

.planning/plans/completed/015-android-release-pipeline.md

@@ -1,5 +1,7 @@
 # 015 — Android release pipeline
 
+> **Completed.** The pipeline ships a signed APK from CI on every `v*` tag; `docs/android-release.md` is its operating document.
+
 Ship an Android APK from CI on every version tag, published to the Gitea
 generic package registry so Obtainium can poll a plain URL.
 

.planning/plans/completed/015-multi-artist-credits.md

@@ -1,5 +1,7 @@
 # 015 — Multi-artist credits, navigable
 
+> **Completed.** Phases 1, 2 and 4 shipped. Running the ingest against the real dump and publishing an artifact that carries credits is **#88**; Phase 3 (`file_artists`) is **#89**, blocked on it.
+
 ## The problem
 
 A track credited to more than one artist has exactly one navigable

.planning/plans/completed/016-android-feature-parity.md

@@ -1,5 +1,7 @@
 # 016 — What Android parity would actually take
 
+> **Completed.** Sections A, B1, B2 and B4 shipped. B3, writing tags on the device, is now **#87**; the device-found UI faults are #51–#72, sequenced by #73.
+
 > **Status: all of section A is done.** A1–A3 landed with "let the app
 > reach the user's music"; A4 (MediaSession, transport notification,
 > audio focus) landed with "survive the screen locking". The direction

.planning/plans/completed/018-supported-sizes-and-the-queue-model.md

@@ -0,0 +1,327 @@
+# 018 — Supported sizes, and what the queue panel is
+
+**Issue:** #24 (`Area/Shell-Nav`, `Priority/High`, `Reviewed/Confirmed`)
+**Unblocks:** #55 (queue as a screen) — a real Gitea dependency
+**Relates:** #69 (page-header overflow), #12 (mini-player), #51 (small-screen umbrella)
+**Status:** complete — #24 shipped as PR #132, and the matrix's last
+unkept promise closed with #69.
+
+#73 puts this first in Phase 2 and hangs the rest of the phase off it,
+so the decision has to be written down and arguable before any CSS
+moves. This document is the decision. Everything below the matrix is
+either a measurement or an argument for one of the four choices #24
+asks for.
+
+---
+
+## What is actually wrong, measured
+
+Against the running app (`make dev-headless SEED=default`, Chromium),
+Playlists, sweeping the viewport with the queue open and closed. The
+number that matters is how much of the page header survives.
+
+| viewport | sidebar | queue | main panel | header needs | actions clipped |
+|---|---|---|---|---|---|
+| 1280×800 | 200 | open 321 | 759 | 759 | — |
+| 1000×700 | 200 | open 321 | 479 | 747 | New Playlist, New Smart Playlist |
+| **900×600** | 200 | open 321 | **379** | 747 | **all three** |
+| 800×600 | 56 | open 321 | 423 | 747 | all three |
+| 700×600 | 56 | open 321 | 323 | 747 | all three |
+| 390×780 | — | open 321 | **69** | 747 | all three |
+| 320×600 | — | open 321 | **0** | 747 | all three |
+| 900×600 | 200 | closed | 700 | 747 | New Smart Playlist |
+| **800×600** | 56 | closed | 744 | 747 | **New Smart Playlist (158/162px)** |
+| 320×600 | — | closed | 320 | 747 | all three |
+
+Five things in that table are not in the issue.
+
+**The header clips at the supported minimum with the queue closed.**
+At 800×600 — the size `backend/config/window.go` enforces and the only
+size this app *promises* — "New Smart Playlist" loses 4px of its 162.
+#24 reads as a queue-panel bug; the queue makes it dramatic, but the
+header overflows on its own at the minimum window.
+
+**900×600 is worse than 800×600, because the sidebar expands at 900.**
+`AUTO_COLLAPSE_VIEWPORT` collapses the sidebar to icons *below* 900, so
+at 899px the main panel is 843px and at 900px it is 700px. The worst
+desktop case is therefore not the minimum window; it is the pixel
+immediately above the collapse. Anything that tests "the minimum" and
+stops has not tested the worst case, which is what
+`layout-overflow.spec.ts` does today.
+
+**At phone widths the queue is not a drawer, it is an amputation.**
+`queue-panel`'s host is `flex-shrink: 0; width: 0`, going to
+`width: var(--queue-width, 320px)` under `[open]` — it is *in the flow*
+of `.content-area`, so it takes its width from the main panel rather
+than covering it. At 390px that leaves 69px of the page; at 320px it
+leaves **0px**, and the app is not degraded but gone. This is the
+measurement #55 needs and did not have.
+
+**Only Playlists overflows.** Sweeping all ten primary views at 900×600
+and at 390×780, every other header reports `scrollWidth ==
+clientWidth`, and Albums at 390px renders title, count and sort
+legibly (checked on a screenshot, not just the number). #69 is
+therefore one view's action set — three text buttons totalling 390px —
+and not a systemic header failure, though the *rule* still belongs in
+`page-header`.
+
+**Both reasons in `MinWidth`'s comment are stale.** It says the floor is
+800×600 because "below ~780 the header's subtitle wraps" and "below
+~600 tall the eleven sidebar items no longer fit". The subtitle is
+`display: none` below 900 (index.css), and the sidebar host is
+`overflow-y: auto` — at 600×460 its `scrollHeight` is 434 against a
+332px client, and Settings is reachable after scrolling. Neither
+mechanism can happen any more. That does not mean the floor should
+move; it means its stated reason no longer supports it, which is worse
+than either answer.
+
+*(Care needed: my first probe for the sidebar scroller searched
+`shadowRoot.querySelectorAll('*')` and reported "items are
+unreachable", because the scroller is the **host** and a host is not in
+its own shadow root. The claim in CLAUDE.md is correct.)*
+
+---
+
+## Decision 1 — the supported size matrix
+
+Three bands. Two of them already exist and are already argued; what is
+new is that they are written down as a *promise*, and that the queue is
+part of it.
+
+| band | width | navigation | queue | promise |
+|---|---|---|---|---|
+| **Phone** | < 600 | `bottom-nav` + drawer | overlay, full width | reflows; nothing needs sideways scrolling; fits 320px |
+| **Compact** | 600 – 899 | icon sidebar | overlay + scrim | nothing is clipped or unreachable at any width in the band |
+| **Desktop** | ≥ 900 | labelled sidebar | inline where it fits (see decision 2), else overlay | as Compact |
+
+And one promise across all three: **no action is ever unreachable.**
+That is the sentence #69 asks for and it is the one the matrix exists
+to make checkable.
+
+**400% zoom** keeps the meaning it already has: WCAG 1.4.10 names 320px
+as the reflow target, the phone band covers it, and
+`layout-overflow.spec.ts` already asserts a 320px viewport needs no
+sideways scrolling. What changes is that the *queue* must be part of
+that assertion — it is not today, and with the queue open at 320px the
+main panel is 0px wide, which no current test can see.
+
+**The window minimum stays 800×600**, and its comment gets the real
+reason. The old mechanisms are gone, but the floor is still where the
+Compact band's chrome stops being comfortable, and lowering it would
+mean promising the desktop layout at sizes where only the phone layout
+works. The interesting consequence is decision 4.
+
+---
+
+## Decision 2 — the queue is an overlay when it cannot afford to be a column
+
+**The rule.** The queue panel renders inline — in the flow, as today —
+only while
+
+```
+viewport − sidebar − queueWidth ≥ 480
+```
+
+and as an overlay with a scrim otherwise.
+
+**Why it cannot be a media query**, which is the load-bearing half:
+the queue's width is *user state*. It is drag-resizable between 200 and
+500px and persisted (`--queue-width`, `MIN_WIDTH`/`MAX_WIDTH` in
+`queue-panel.ts`). A breakpoint at a fixed viewport width silently
+assumes the default 320, and is wrong by 180px for a user who has
+dragged the panel wide — in the direction that hurts, since a wider
+queue is exactly when the content can least afford it. So the mode is
+computed from the measured widths and published as an attribute, the
+way `data-active-view` already is, and the CSS keys off that.
+
+**Why 480, honestly.** There is no cliff to derive it from. The track
+list rescales its columns continuously — at main widths from 900 down
+to 544 its `--grid-cols` shrink from 213px to 124px with
+`rowOverflow=0` throughout — and the album grid steps 3 columns to 2
+somewhere between 564 and 644 without breaking. So this is a judgement,
+anchored on two things: it keeps the *default* window (1100 wide, main
+= 580) inline, because the inline queue is a desktop affordance people
+choose and turning it into an overlay for the common case would be a
+regression in feel; and it puts every case measured as broken —
+900×600 at main=379, and every phone width — on the overlay side.
+1024×768 lands at main=504 and stays inline.
+
+**The scrim is the other half of the issue's complaint** ("make the
+queue obviously an overlay *over* the content so it reads as something
+to close"). An overlay queue gets a scrim, closes on scrim click and on
+Escape, and returns focus to `#queue-button`.
+
+**What must not change**: #55's Direction is explicit — one component,
+two mount points, do not fork it. The overlay is a *presentation* of
+the same `queue-panel`, so the roving tab stop, Alt+Arrow reorder, drag
+reorder, selection semantics and the `virtualizer.requestUpdate()` on
+selection and current-track change all come along untouched. This
+decision deliberately stops short of #55's detail-view mount, but it is
+the shape that makes it possible, and it unblocks it.
+
+---
+
+## Decision 3 — #69 is its own PR, and here is the finding that decides it
+
+`page-header` **cannot collapse its own actions**, and that is not an
+effort estimate but a fact about the API. Actions arrive through
+`<slot name="actions">` as arbitrary light-DOM markup — Playlists slots
+a `<div class="header-actions">` of three `<button>`s with click
+handlers, drag handlers and a conditional class. A component cannot
+move another component's light-DOM children into a dropdown and keep
+their behaviour; there is nothing generic to render as a menu item.
+
+So the overflow rule needs an *actions API* — hosts declaring
+`{icon, label, handler, priority}` data that `page-header` can render
+either as buttons or as menu items — which is a change to all three
+hosts that slot actions, not a rule added in one place. That is a
+different piece of work from this one, it is independently verifiable,
+and the desktop half of #69's symptom is removed by decision 2 anyway
+(the queue stops eating the header's width).
+
+It therefore stays #69, gets the finding above recorded on it, and
+follows immediately after this. What *this* plan owes it is the
+promise in the matrix — no action unreachable at any supported size —
+and the measurement that the only offender today is Playlists.
+
+**And the promise is not kept yet, which is the honest version of a
+claim this document made in its first draft.** "Decision 2 removes the
+desktop half of #69's symptom" was too strong. Measured after phase 2,
+at 900×600 on Playlists:
+
+| | before | after |
+|---|---|---|
+| queue open | main 379px, **all three** actions clipped | main 700px, **one** clipped |
+| queue closed | main 700px, one clipped | unchanged |
+
+So the queue's *contribution* is gone — open and closed are now
+identical, which is the whole of what this decision owed — and the
+residual "New Smart Playlist: 114/162px" is the header overflowing on
+its own, at a size the queue never touched. #69 is still a live defect
+at a supported size, and the matrix's promise is what will close it.
+
+---
+
+## Decision 4 — a very small window becomes the phone layout, not the mini-player
+
+#24 asks whether a very small window should switch to the mini-player
+(#12) "or simply refuse to go there". Both options in the question are
+worse than the one the codebase already has.
+
+**#12 is a second window, not a mode.** Its findings say so: v3
+supports multiple windows, `AlwaysOnTop` is a window *option*, and the
+frontend would need an entry branch mounting only the mini-player root
+for a second window loading the same bundle. Turning the main window
+into a mini-player at some width conflates the two: it would throw away
+the user's navigation state on a resize, and it puts the MPRIS question
+(#12's own open question — media controls are process-level and must
+not be per-window) on a code path that a drag can trigger by accident.
+
+**And "refuses" is unnecessary, because the reflow already exists.**
+The phone band is real, tested, and reached by width alone — a desktop
+window narrowed below 600px already gets `bottom-nav` and the phone
+shell. That is a better answer than refusing: it is strictly more
+usable than a hard minimum, it costs nothing new, and it is the same
+code Android runs, so it stays exercised.
+
+So: the main window reflows and never becomes a mini-player; #12 stays
+a separate always-on-top window and is not blocked by, or coupled to,
+this decision. The window minimum stays 800×600 for the reason in
+decision 1 — but the phone band is what happens below it, not a
+refusal, which is why the minimum is a comfort floor rather than a
+correctness one.
+
+---
+
+## Phases
+
+1. **This document**, linked from #24, with the matrix reported on the
+   issue and #55 told whether it is unblocked. *(no code)* — **done**
+2. **The queue's overlay mode** — computed mode attribute, scrim,
+   Escape and scrim-click close, focus return. The inline path is
+   unchanged above the threshold. — **done**
+3. **The window minimum's comment** — replace both stale reasons with
+   the measured ones. No value change. — **done**
+4. **Verification**, below. Including the specs that must change
+   because they assert the old behaviour. — **done**
+
+#69 follows as its own branch; #55 became unblocked at phase 2.
+
+## What landed, measured
+
+Main panel width with the queue open, before and after:
+
+| viewport | before | after | mode |
+|---|---|---|---|
+| 1280×800 | 759 | 759 | inline |
+| 1100×720 (default window) | 579 | 579 | inline |
+| 1024×768 | 503 | 503 | inline |
+| 900×600 | **379** | **700** | overlay |
+| 800×600 | 423 | 744 | overlay |
+| 390×780 | **69** | **390** | overlay |
+| 320×600 | **0** | **320** | overlay |
+
+The scrim is perceptible but subtle on a dark ramp, which is worth
+knowing before someone "fixes" it: sampled from the screenshots at
+900×600, the main panel's background goes 33,37,41 → 18,20,23 and a
+row's text 242 → 133. It covers the **content area only** — not the
+sidebar or the transport — on purpose: the queue is not modal, and
+leaving the navigation live means the scrim reads as "this is over the
+content" (which is what #24 asked for) without pretending the rest of
+the app is unavailable.
+
+## What #69 did with the promise, and one thing this plan got wrong
+
+#69 landed on its own branch as decision 3 said it would, and the
+matrix's *no action is ever unreachable at any supported size* is now
+kept rather than promised. Measured on Playlists, actions clipped:
+
+| viewport | before #24 | after #24 | after #69 |
+|---|---|---|---|
+| 900×600, queue open | all three | one (114/162px) | none |
+| 900×600, queue closed | one | one | none |
+| 800×600, queue closed | one (158/162px) | one | none |
+| 390×780 | all three | all three | none |
+| 320×600 | all three | all three | none |
+
+The shape was the one decision 3 predicted — an actions API first, an
+overflow rule second — and all three hosts that slot actions migrated.
+
+**What this document got wrong is smaller and worth keeping.** Decision
+1 says the header's minimum is a *comfort* floor and that only the
+queue and the actions compete for the header's width. They are not the
+only two: every child of that flex row was `flex-shrink: 0`, so
+whatever came last lost, and the actions come last. At 320px the sort
+control alone is 172px of the header — so with every action already
+collapsed into the menu, the *menu button* was 76px off the right edge.
+The promise was still broken with nothing left to collapse.
+
+That is why #69 also had to decide what gives way: the title (which the
+navigation also states) and, below 600px, the word "Sort:" (which the
+direction arrow implies). Neither is an action, which is the rule the
+matrix actually encodes — **an action is a capability and everything
+else on that row is a label.**
+
+## Verification, and what each tier cannot see
+
+- `make ui-test` — the queue panel's mode logic is component-tier
+  work and belongs there. It **cannot** see the shell: the threshold is
+  computed from the sidebar and viewport, which do not exist in that
+  tier.
+- `make e2e` — `layout-overflow.spec.ts` gains the queue-open case at
+  every band (it has none today, which is why main=0px at 320px has
+  never failed anything) and **gains 900×600**, since the minimum is
+  not the worst case. `queue-toggle-state.spec.ts` and
+  `phone-shell.spec.ts` both touch the panel and must be re-read before
+  editing.
+- **Screenshots at every band, read by a human.** This is not optional
+  here: `layout-overflow.spec.ts` asserts the *shell* needs no sideways
+  scrolling and passes on a build whose album header clips its own
+  buttons (measured this session at 390px; filed on #66). Clipping
+  *inside* a component is invisible to it, and clipping is this issue.
+- `make ui-visual` **cannot help at all** — the component tier renders
+  the token fallbacks, because the theme only reaches `:root` in the
+  real app.
+- Accessible names via `page.getByRole(...)`, never a shadow-root
+  query. A drawer with a scrim is exactly the shape that grows a
+  nameless control, and this repo has shipped one three times.

.planning/plans/completed/019-android-touch-model.md

@@ -0,0 +1,408 @@
+# 019 — The Android touch model
+
+**Issue:** #63 (`Area/Library-UI`, `Kind/Feature`, `Priority/High`)
+**Depends on:** #60 (bottom-sheet menus) — closed, merged as PR #176
+**Relates:** #67 (inline links into the menu), #71 ("More" nav), #54
+(native feel), #5/#8 (selection, drag to queue — the desktop semantics
+being diverged from)
+**Status:** shipped (phases 1-4). Its one deliberate remainder is #200.
+
+#73 puts #60 first in Phase 4 because it is "the presentation every
+other item needs", and this is the next one. The Direction on #63 asks
+for the interaction model to be designed as one piece before any of it
+is built, because it *reassigns an existing gesture* rather than adding
+one — `utils/long-press.ts` currently owns the 500ms hold, and every
+context menu in the app is downstream of it.
+
+This document is that design. Everything below is a measurement, or an
+argument for one of the choices #63 leaves open.
+
+---
+
+## The mapping
+
+| gesture | pointer is a finger | pointer is a mouse |
+|---|---|---|
+| single tap / click | **play the row** | select the row |
+| double | — | play the row |
+| long press (500ms) | **enter selection mode** | — |
+| right-click | — | context menu |
+| swipe right | **add to queue** | — |
+| drag | reorder / drag to playlist | reorder / drag to playlist |
+
+Three of those are #63's report unchanged. Two are decisions it left
+open, and one is a deliberate divergence.
+
+---
+
+## Decision 1 — the predicate is the pointer, not the platform
+
+#63 says "the row component needs a platform-aware interaction layer
+rather than shared handlers". It needs an interaction layer; it should
+not be platform-aware.
+
+**The question a row has to answer is not "am I on Android" or "is the
+viewport under 600px" but "what made this event".** `pointerType ===
+'touch'`, read off the event that is being handled, which is already
+how `long-press.ts` decides (`if (e.pointerType !== 'touch') return`)
+and is the only such test in the frontend today.
+
+This is #64's rule — the predicate is named after the capability, not
+the platform — and it carries #64's warning with it. Keyed on a width:
+
+- an Android **tablet** at 600px or more gets click-selects /
+  double-click-plays on a touchscreen, which is the exact inversion
+  this issue exists to fix, on the platform it exists for;
+- a **touchscreen laptop** cannot be described at all, because both
+  pointers are live in the same session on the same row;
+- and a narrow desktop window gets phone semantics with a mouse.
+
+Per event, all three are right for free, and there is no second
+declaration of what a phone does — the thing CLAUDE.md declines to add
+every time it comes up.
+
+**Measured, so this is not an assumption about the WebView.** On the
+reference device (TLP301, Android 14, WebView Chrome 113, 424x439),
+driving a real tap with `adb shell input tap`:
+
+```
+[["down","touch",78,94],["touchstart","touchstart",0,0],["up","touch",78,94]]
+```
+
+`PointerEvent` exists, `pointerType` is `"touch"`, `maxTouchPoints` is
+5, and `(pointer: coarse)` / `(hover: none)` both match.
+
+---
+
+## Decision 2 — there is no double-tap, and the number is why
+
+#63 asks for *single tap → play* **and** *double tap → context menu*.
+Those two cannot both be honoured. The first tap of a double tap is
+indistinguishable from a single tap until the interval expires, so
+"tap plays" necessarily becomes "tap waits to find out whether you
+meant something else, then plays". The app already owns that constant:
+`utils/explore-link.ts` holds a navigation for `DOUBLE_CLICK_GRACE_MS
+= 250` for precisely this reason.
+
+**What it would be added to, measured on the device.** Six runs, from
+the play command to the backend's `TrackChanged`:
+
+```
+155, 123, 85, 56, 91 ms          median ~100
+```
+
+So the app's primary interaction is ~100ms, and a double-tap
+discriminator makes it ~350 — **3.5x, of which 250ms is spent
+deliberately doing nothing** — paid on every track anyone ever plays,
+in order to reach a menu.
+
+It is also against the platform's convention, which counts for more
+than usual here because this is the phone build and nothing else:
+long-press is *how you select* on Android (Gmail, Files, Photos),
+double-tap is zoom or nothing, and a list's menu is either the
+long-press sheet or a per-row overflow.
+
+**So the menu and the selection action bar become the same surface**,
+which is the convention and removes a concept rather than adding one.
+Long-press selects the row it was made on and raises the action bar;
+the bar's actions *are* the context menu's actions, contextualised to
+whatever is selected — one row or forty. #60's bottom sheet stays
+behind it as the overflow, so `contextMenuStyles`, `MenuKeyboard` and
+`menu-surface` are reused rather than reimplemented.
+
+---
+
+## Decision 3 — tap-to-play and selection mode ship together
+
+The obvious phase order is "tap plays first, it is the smallest
+change". It is wrong, and the reason is a capability that exists today
+and is easy to miss.
+
+**A touch user can already multi-select**: tap selects (the desktop
+semantics, which a finger currently gets), and the long-press menu then
+acts on the selection. Move tap to play without shipping selection mode
+in the same change and there is a window — a release, if it lands — in
+which selecting forty tracks to add to a playlist is impossible on a
+phone. That is a regression dressed as an increment.
+
+So phase 1 is both, or neither.
+
+---
+
+## What the code looks like now
+
+| surface | how it binds | selection |
+|---|---|---|
+| `track-list` | delegated on the virtualizer: `click`, `dblclick`, `contextmenu`, `dragstart` | `SelectionController` |
+| `queue-panel` | delegated, same shape | `SelectionController` |
+| `playlist-details` | per row | `SelectionController` |
+| `smart-playlist-details` | per row | `SelectionController` |
+
+All four already share `SelectionController`, and all four resolve a
+row from an event by `data-index` / `data-file-path` on the row. So the
+gesture layer has one shape to talk to, and "selection mode" is a flag
+on the controller they already have rather than a fifth concept.
+
+`utils/long-press.ts` is one document-capture listener that synthesises
+a `contextmenu` — the seam that needed no component to opt in. **This
+plan keeps that shape and changes what the gesture means**, which is
+why it is a rewrite of that file rather than a second listener set: two
+document listeners both claiming the 500ms hold is the fault the file's
+own header warns about.
+
+---
+
+## Two measurements that decide the implementation
+
+**`touch-action` is `auto` on both the virtualizer and the rows.** With
+`auto` the browser owns panning on both axes, so a horizontal drag can
+be claimed as a scroll and our gesture ends in `pointercancel`
+mid-swipe. A row that wants a horizontal swipe has to declare
+`touch-action: pan-y`: the browser keeps the vertical pan (which is the
+virtualizer's scroll, and must stay native or the list stutters) and
+hands us the horizontal axis. This is the single most likely way for
+swipe-to-queue to "work in Chromium and not on the phone".
+
+**The row is 424x52 on the device**, so a swipe threshold in px is a
+fraction of a row height, not of a screen.
+
+**And the third one was found by building phase 1 and then running it**
+— it is not something any browser tier can report. Chrome 113's Android
+WebView **fires its own `contextmenu` on a long press**. `long-press.ts`
+stood down when a trusted one arrived, which was right while both paths
+ended in the same place; once a hold can mean selection mode they end
+in different places, and standing down means the gesture silently does
+the *old* thing. Measured, before the fix:
+
+```
+{"log":["contextmenu isTrusted=true"],
+ "state":{"bar":null,"menuActive":true,"selected":1}}
+```
+
+`yj-long-press` was never announced at all, the context menu opened,
+and all 26 tests in the component tier passed — dispatched pointer
+events do not make a browser synthesise a `contextmenu`.
+
+So the browser's event is a **trigger, not a competitor**: the gesture
+is announced from it, and only a component that claims it suppresses
+the native menu. Unclaimed, it propagates untouched. That is the same
+"browser wins" outcome, reached by asking instead of assuming — and
+verified both ways on the device, a track row entering selection mode
+and an album card still opening its menu.
+
+The tier could not *find* it and can *hold* it: a test cannot dispatch
+a trusted event, but this module has always told its own apart by
+identity rather than `isTrusted`, so an untrusted one from a test takes
+exactly the browser's path.
+
+---
+
+## A tier note: this one can be driven, not only measured
+
+`adb shell input tap|swipe` reaches the WebView as real pointer events,
+which the log above is evidence of. So for the first time the Android
+tier can *perform* the thing under test rather than describe the page
+afterwards — a long press is `input swipe X Y X Y 600`, a swipe right
+is `input swipe X Y X+N Y 120`.
+
+Device CSS pixels from device pixels, on this phone:
+`css = (device - 59) / 2.564` vertically, `css = device / 2.564`
+horizontally (measured from the tap above: 200,300 arrived as 78,94).
+
+This does not make the device a spec tier — it does not run in CI and
+`make ui-test` still has to carry the assertions. It makes "does the
+gesture actually fire on Chrome 113" answerable in seconds.
+
+---
+
+## Phases
+
+**Phase 1 — the seam, tap-to-play, selection mode.** `utils/
+touch-gestures.ts` replacing `long-press.ts`: pointer-typed
+recognition of tap / long-press / horizontal swipe, dispatched as
+composed custom events so a delegated listener in any shadow root
+still works. `SelectionController` gains a mode. `track-list` acts on
+tap and enters the mode on long press. The action bar.
+
+**Phase 2 — swipe right to queue**, with the `touch-action: pan-y`
+finding above and a reveal-and-snap affordance. **Shipped**; what the
+device said about it is the section below.
+
+**Phase 3 — the other three surfaces**, which is mostly wiring, since
+they already share the controller. **Shipped**, and it was not entirely
+wiring — see below.
+
+**Phase 4 — what this leaves behind.** The inline `explore-link`s in a
+row are a single-click target inside a row whose single tap now plays;
+that conflict is #67's, and this plan should not pre-empt its answer
+beyond making tap-to-play win on touch. **Shipped.**
+
+## Phase 3 was not symmetric, in two places
+
+**A tap on a queue row plays that position**, not the list. Copying
+`track-list`'s tap — which sets the queue to the list the row is in —
+would rebuild the queue *from* the queue, discarding its source, its
+shuffle order and everything a user had inserted by hand. It reads as a
+no-op and is not one.
+
+**The queue panel has no swipe, deliberately.** A right swipe means
+*add to the queue* everywhere else it exists, and a queue row is
+already in the queue; the only thing it could mean there is *remove*,
+which is the same gesture with the opposite effect one screen away —
+the fault `utils/icon-language.ts` exists to have fixed for glyphs.
+Removing a queue row is on the row itself (the ×), on its bottom sheet
+since #60, and on the selection bar this phase gave it. The assertion
+is that its rows do **not** carry `data-swipe`, so a swipe there cannot
+silently become a second meaning for the app's one horizontal gesture.
+
+And the affordance became `utils/swipe-to-queue.ts` rather than being
+copied twice. Three lists want it; three copies of "how far is far
+enough" is three chances for them to disagree, which is what
+`utils/library-status.ts` and `utils/ownership.ts` each exist to have
+stopped happening. The shared stylesheet is keyed on `[data-swipe]`
+rather than on a class name, because the three lists call their rows
+two different things and the `touch-action` half of the device fix has
+to reach all of them.
+
+## Phase 4 was already true, which is why it is asserted
+
+A claimed tap has its click swallowed at document capture, so an
+`explore-link` inside the row never sees one and tap-to-play wins with
+no rule of its own. Nothing in the suite would have failed if that
+stopped covering the link, and the symptom — tapping a track's *title*
+navigating to its album instead of playing it — is one a phone user
+meets constantly and a mouse user never does.
+
+**Its test was vacuous when written**, in the way this file keeps
+finding: the tap helper dispatched `pointerdown` and `pointerup` and no
+`click`, so there was nothing to swallow and the assertion held on any
+build. It sends the trailing click now, which also strengthened phase
+1's "a tap plays and does not also select". The fixture needed an MBID
+for the same reason — without one the link asks the backend for a local
+album first and gives up when nothing answers, so "it did not navigate"
+was true of a working build and a broken one alike.
+
+---
+
+## What phase 2 measured, which was not what phase 2 predicted
+
+The `touch-action` finding above is **half** of the answer, and
+shipping only that half would have been the exact failure it warns
+about. Driving a real finger with `adb shell input swipe` across a
+track row, three values, all three on the device:
+
+```
+touch-action: auto    pointerdown, 1 move,  pointercancel
+touch-action: pan-y   pointerdown, 2 moves, pointercancel
+touch-action: none    pointerdown, 2 moves, pointercancel
+```
+
+`touchmove` kept firing in all three. So **Chrome 113's WebView
+cancels the pointer stream ~16px into any drag whatever `touch-action`
+says**, and a swipe recognised from `pointermove` — which is what the
+rest of this module is built on — is a swipe that dies 16px in.
+
+The other half is a **non-passive `touchmove` calling
+`preventDefault()`**: with it, the same swipe ran to 12 moves and a
+`pointerup` at full travel. And both halves are required, which was
+measured rather than assumed — with the `preventDefault` in place and
+`touch-action` back at `auto`, the gesture died after **one** move.
+The reading is that `auto` lets the browser commit to a horizontal pan
+on the first move past slop, before any threshold of ours can have
+been crossed, while `pan-y` leaves it undecided long enough for the
+second move to claim it.
+
+`none` is the one value to avoid: the list stopped scrolling at all.
+With the shipped pair, a vertical drag still scrolls the virtualizer
+81px on the same run that a horizontal one survives.
+
+**`draggable="true"` is not a competitor**, which is the other thing
+the device was asked. No `dragstart` fires from a touch drag on this
+WebView at all, so the drag-to-playlist attribute on every row needs no
+pointer-type gate.
+
+### And it found a phase 1 defect that no tier can see
+
+The native `contextmenu` arrives in **either** order, and phase 1 only
+handled one of them. `nativeSeen` covers the browser's menu arriving
+*during* the hold. The reverse — our 500ms timer firing first, a
+component claiming it, and Chrome delivering its own `contextmenu`
+50–70ms *later* — was suppressed by nothing, so the context menu
+opened on top of the selection bar. Measured over four holds:
+
+```
+hold 1  yj-long-press, then contextmenu isTrusted=true   menu open
+hold 2  yj-long-press                                    clean
+hold 3  yj-long-press, then contextmenu isTrusted=true   menu open
+hold 4  yj-long-press                                    clean
+```
+
+Two in four, on the one surface #63 exists to have changed, and
+invisible to both browser tiers because neither synthesises a
+`contextmenu` from a dispatched press. A press that has produced its
+outcome now suppresses a late one whichever branch it took; six holds
+on the fixed build, six clean.
+
+### The rules phase 2 settled
+
+- **A swipe is not a selection.** It queues the row it was made on,
+  unless that row is one of several *explicitly* selected — the same
+  rule the context menu answers with, because a bar reading "40
+  selected" beside a gesture that quietly queues one of them is two
+  answers to one question. It never changes the selection, which is
+  where it differs from a right-click.
+- **Rightward only.** Nothing is bound to a leftward swipe and
+  claiming one would take a gesture away to do nothing with it.
+- **The commit threshold is a fraction of the row** (0.3, floor 72px),
+  because the row is 424x52 on this device and a bare pixel count is a
+  fraction of a row height on one screen and a third of the width on
+  the next.
+- **The affordance is not only a colour** (WCAG 1.4.1, the rule the
+  playing-row marker exists for): the pane carries the queue icon and
+  words, the words change at the threshold ("Add to queue" → "Release
+  to add" → "Added"), and the outcome is announced in a live region.
+- **The row does not move; its cells do.** `.track-row` is
+  `contain: strict` with `overflow: hidden`, so a pane held at the
+  row's original position while the row translates is a pane at a
+  negative offset inside a clipping box and is simply not painted.
+  Sliding the cells needs no wrapper element in a row that is already
+  a grid.
+- **The travel is written to the row's own style, not rendered.** One
+  render at the start, one at the threshold, one at the end; a
+  virtualizer re-rendering every visible row per frame of one finger's
+  travel is the thing `perf.m1` is about.
+
+## Open questions
+
+1. **Does selection mode have an escape other than the bar's own
+   close?** *Settled: Escape, here; back, not here.*
+
+   Escape leaves the mode, from `selection-bar` rather than from each
+   of the four hosts — that element exists only while the mode does, so
+   it is the one place a dismissal can be attached and detached with
+   the thing it dismisses. It is the same documented exception the
+   overlaid queue's Escape is: **a dismissal, not a shortcut**, so it
+   is not a panel-scoped binding.
+
+   The back gesture is the half that is *not* done, and deliberately.
+   The obvious version — `selection-bar` pushing a history entry — is
+   precisely the fault `navStack` was deleted for: the shell owns the
+   stack (#6/#55) and is the only thing that calls `pushState`, so that
+   two stacks cannot disagree about what one press means. Four lists
+   each reaching for `history` is four stacks. It is also wrong on its
+   own terms, since a mode is per-component and a user who enters one,
+   navigates away and returns has an entry for a mode that no longer
+   exists. #55 settled the shape for a *place*; a mode is not one,
+   which is why it could not simply inherit that answer.
+
+   What it wants is one shell-owned register of dismissible surfaces,
+   which would retro-fit the queue overlay, the dialogs and this alike
+   rather than adding a fourth private answer. **#200.**
+
+2. **Does a tap on a row's favourite icon still toggle it in normal
+   mode?** *Settled in phase 1: yes.* A control inside the row keeps
+   its own tap — the gesture is simply not claimed there, so the click
+   behind it falls through untouched. It is the same rule the shortcut
+   service has for a focused control that owns a key, and it is what
+   keeps the 44px favourite target (#56) from becoming a 44px play
+   target. The queue row's × is the second instance of it.

.planning/plans/completed/autotag-v1.3.md

@@ -1,5 +1,7 @@
 # Autotag (v1.3) — MusicBrainz Autotagger
 
+> **Historical record.** Phases 008–010 shipped, and the scoring engine was subsequently overhauled (`recommend.go`, `rank.go`, `mixedbag.go`), which makes the 011/012 sections below stale in their details. What is actually left is **#90** (auto-accept and entry points) and **#91** (settings, and a way back from the dismissed file-write warning).
+
 The MusicBrainz autotagger, collectively **v1.3**. Builds on the explore-browser API client + cache foundation. Five sequential phases (008–012), each depending on the prior one.
 
 | Phase | Title | Status |

.planning/plans/pending/010-owned-album-catalog-offline.md

@@ -1,195 +0,0 @@
-# 010 — Owned albums, offline
-
-**Status:** not started — and **much smaller than when it was written**
-**Branch:** none yet
-**Created:** 2026-08-13
-**Depends on:** nothing
-**Related:** the `AlbumReleasesFailed` fix that prompted it, and the
-tag-derived completeness that landed after it (same session)
-
----
-
-## What already shipped, and what it leaves
-
-The common case is solved without this plan. `GetAlbumCompleteness`
-reads the "5/12" denominator off the files' own tags — persisted to
-`release_group_recordings.total_tracks`, having been extracted at every
-scan since forever and discarded — and an album that is **MBID-matched
-and complete** now opens with **no catalog call at all**. Identity from
-the MBID, tracklist from the tags; those were the two things the browse
-was being spent on.
-
-So the set this plan still has to serve is not "albums you own a track
-of". It is:
-
-- albums that are genuinely **incomplete** (the catalog is the only way
-  to say *which* tracks are missing — tags give the count, not the
-  names), and
-- albums whose tags **never declared a total**, where completeness is
-  unknowable locally and the catalog is the only source.
-
-On a well-tagged library that is a small minority, which changes the
-economics below considerably: the run is shorter, and the rate limiter
-contention that dominates this design is proportionally less severe.
-Re-measure before building — the answer may now be "the prefetch is
-enough".
-
----
-
-## The problem
-
-Opening an album detail page for an album **you already own** hits
-MusicBrainz. Every time it is not in the response cache, which for most
-of a library is every time, because nothing warms that cache except a
-capped prefetch on the artist page.
-
-The user's framing: *this is a classic example of an album we should
-have had locally.*
-
-## Why we do not have it, despite the discography backfill
-
-`BackfillLibraryDiscographies` / `EnsureArtistDiscography`
-(`backend/explore/searchindex.go:301`, `:397`) do less than the name
-suggests. Per artist, `indexOneArtist` fetches:
-
-- `fetchTopReleaseGroups` — capped at `indexMaxRGs` (50)
-- `fetchTopRecordings` — capped at `indexMaxRecs` (200)
-
-and writes them as **flat `explore_index` rows**. There is no release
-group → tracklist relation anywhere in the index, and no release-level
-rows at all. `explore_index` recordings carry `caa_release_mbid` and
-`release_name`, which name the release used for cover art — not a
-tracklist.
-
-So "we have full discographies for library artists" means *we know
-which albums the artist made, offline*. It has never meant we know
-what is on any of them.
-
-The only store of release-level catalog data in the app is `http_cache`
-under `mb:browse:releases:<rg>` (90-day TTL, `musicbrainz.go:27`),
-populated **only** by a live `BrowseReleases` with
-`Includes: ["recordings", "media"]` at `MaxLimit` — the most expensive
-call the app makes to MusicBrainz. It is warmed by exactly one thing:
-`PrefetchReleases` (`explore.go:746`), capped at 8, called only when an
-artist page renders.
-
-An album opened from the library grid therefore always browses live.
-
-## What to build
-
-**A post-scan backfill that warms the release cache for release groups
-that are owned but not known-complete** — bounded, resumable, and
-shaped exactly like `BackfillLibraryDiscographies`, which is the proven
-pattern for this in the codebase.
-
-The scoping rule is the user's and it is the right one: not "every
-album by every artist in the library" (50 release groups per artist,
-mostly never opened) but albums with owned tracks — narrowed further,
-now, to the ones a local answer cannot already cover. The query gains
-one clause: skip release groups whose `GetAlbumCompleteness` reports
-`complete`.
-
-Sketch:
-
-1. A query for release groups with ≥1 owned track and no warm release
-   cache entry. `release_groups.mbid` is the key; the owned-track join
-   is `audio_files → recordings → release_group_recordings`, the same
-   shape `unenrichedLibraryArtistMBIDs` already uses one table over.
-2. Order by owned-track count descending, so the albums the user has
-   most of are warmed first — same reasoning as the discography
-   backfill's ordering, same benefit if a run is cut short.
-3. Run through `releasesSF`, so it never double-fetches a release group
-   an interactive open is already handling.
-4. Bound a run (`discogBackfillMaxPerRun` has a value to copy) and make
-   it resumable: the resume marker is the response cache itself —
-   `BrowseReleasesCached` already answers "is this one done", so unlike
-   the discography path this needs **no new flag column**.
-5. Trigger it where `BackfillLibraryDiscographies` is triggered, and
-   register it with `jobs` so it has progress, pause and cancel like
-   every other long-running operation.
-
-### The rate limiter is the whole design constraint
-
-> **Update (2026-08-13): the priority half is built, and the sentence
-> below is wrong on a detail.** `e.mb` runs on `mbSearchLimiter`
-> (`NewRateLimiterBurst(3, 1)`); the 1 req/s `NewRateLimiter()` cited
-> here is the *artist image* limiter. Both are shared and both were
-> FIFO. `RateLimiter.WithBackgroundLane` + `WithBackgroundPriority(ctx)`
-> now make a marked caller yield to interactive work and pace at 1/s,
-> and `jobs.KindCatalogEnrich` + `startBackfillJob` give the existing
-> backfills progress and cancel. **"Do not start until the priority
-> question has an answer" is satisfied** — mark this backfill's context
-> and register it the way `BackfillLibraryDiscographies` now is.
-> `PrefetchReleases`' cap of 8 is still unrevisited.
-
-One shared `NewRateLimiter()` at 1 req/s (`explore.go:84`) serves this,
-`PrefetchReleases`, and every interactive browse. A backfill over a
-few thousand owned albums is *hours* of wall clock at that rate — which
-is fine for a background job, and not fine if it starves the album page
-the user is looking at right now.
-
-That is the real work in this plan, and it is not the query:
-
-- Interactive browses need to **jump the queue**. Today they cannot;
-  there is one limiter and it is FIFO.
-- `PrefetchReleases`' cap of 8 was sized when nothing else competed for
-  the limiter. Revisit it in the same change.
-- The 60 s fallback the `AlbumReleasesFailed` fix installed is sized
-  for today's contention. If a backfill can queue behind it, that
-  number is wrong again — which is an argument for priority, not for a
-  bigger number.
-
-Do not start the query until the priority question has an answer.
-
-## The alternative that was considered and rejected
-
-**Project release-group tracklists in the dump build and ship them in
-the artifact.** The data is there: `canonical_musicbrainz_data.csv`
-carries `release_mbid` *and* `recording_mbid`
-(`dumpcatalog.go:520`), and `release_to_rg` already maps release →
-release group. It is derivable from bytes the index build already
-streams, with no new API surface at all, and it would work offline on
-first launch with no per-user backfill.
-
-It is rejected **for this plan** because the artifact is built
-centrally and is byte-identical for every user, so "albums the user
-owns a track of" cannot be a filter on it. Shipping tracklists for the
-whole catalog means per-recording rows against a ~900 MB artifact
-budget (~426 B/row measured), and gating on a popularity floor means it
-is absent for exactly the obscure albums a local backfill would have
-covered.
-
-Worse than absent, in fact — and this is the argument that actually
-kills it. The floor is not one number over artists; it is a **per
-artist track budget** (`dumpcatalog.go:58-89`): 50 tracks for a tier-A
-artist, 25 for tier B, 12 for tier C. A projected tracklist would
-therefore be *whichever* of an album's tracks survived that budget,
-with nothing marking the rest as absent — so the album page would count
-owned against a truncated denominator and render "Play 7 of 9" for a
-twelve-track album. That is a confident lie, where the honest states
-this plan's alternative produces (complete / incomplete / unknown) are
-at worst silent.
-
-Note that `markLibraryArtists` (`dumpcatalog.go:246`) already grants
-every library artist full coverage — 500 tracks, 100 release groups —
-by reading the local library, so the per-user tailoring this option
-supposedly cannot have does exist in code. It is a no-op in the CI
-build (empty library), and reaching it means a **local** dump build:
-the ~205 GB, half-a-day download the entire artifact design exists to
-avoid. Whoever finds that function next should read this paragraph
-before getting excited about it.
-
-Worth revisiting if the artifact ever gains per-user tailoring, or if a
-measurement shows the row count is smaller than feared. Note it also
-yields the *canonical* tracklist rather than MusicBrainz's full version
-list, so the versions dropdown would still browse live when opened.
-
-## Done when
-
-- Opening an owned album that has never been opened before renders its
-  catalog tracklist with no network call, after one backfill run.
-- An interactive browse issued while the backfill is running is not
-  delayed by it.
-- The backfill appears in the jobs indicator, and can be paused and
-  cancelled there.
-- A second run after a completed one does approximately nothing.

.releaserc.yml

@@ -1,8 +1,19 @@
 # semantic-release configuration.
 #
-# Runs on pushes to main from .gitea/workflows/release.yml: determine the
-# version from the Conventional Commits since the last tag, write the
-# changelog, commit it, push the tag, and create the Gitea release.
+# Run by hand from .gitea/workflows/release.yml, which has no push
+# trigger: determine the version from the Conventional Commits since the
+# last tag, write the changelog, push the tag, and create the Gitea
+# release.  A release is a shipment rather than a merge, and the commits
+# accumulate until someone says so -- this file needs to know nothing
+# about that, because reading everything since the last tag is what it
+# already did.
+#
+# `branches` is main and only main.  A `prerelease: true` channel is the
+# obvious next edit here and is the one to think twice about: all four
+# publishing workflows trigger on `v*`, which matches `v0.4.0-beta.1`.
+# They carry a prerelease guard now, so the failure is a clean skip
+# rather than a beta in a public tap -- but they are four separate files
+# and this is the line that would turn them on.
 #
 # **There is no `@semantic-release/github` plugin here and there must not
 # be.** Gitea's API is `/api/v1` and is not GitHub's surface. The Gitea

CHANGELOG.md

@@ -5,15 +5,20 @@ The changelog is the releases page:
 <https://git.ljones.me/yonlu/yellowjacket/releases>
 
 Every release there is generated from the Conventional Commits it
-contains, by `.gitea/workflows/release.yml` on merge to `main`. Each one
-carries its notes as its body, grouped by change type, with a link to the
-commit behind every line.
+contains, by `.gitea/workflows/release.yml`. Each one carries its notes
+as its body, grouped by change type, with a link to the commit behind
+every line.
+
+That workflow is **run by hand**, so a release holds everything merged
+since the last one rather than one PR's worth. It used to fire on every
+push to `main`, which made a version per merged PR (issue #115).
 
 **This file is not generated and is not a copy of that.** `main` is a
 protected branch, so nothing pushes a changelog commit back to it — and a
 file that claimed to be a changelog while silently never updating would
-be worse than no file at all. `make release-dry` prints what the next
-merge would release.
+be worse than no file at all. `make release-dry` prints what a release
+run would cut right now, and the workflow's own `dry_run` input answers
+the same question from CI.
 
 History before `v0.0.1` is in `git log`. The versions before it were cut
 by hand and are not on the releases page; the entries this file used to

Makefile

@@ -172,12 +172,17 @@ ui-setup: ## Install the Vitest browser provider's own Chromium (once)
 bindings-check: ## Fail if the generated bindings are stale
 	@./scripts/bindings-check.sh
 
+# Two CSS traps that report a long way from their cause, or not at all.
 # A backtick inside a comment in a css`` literal ends the literal, and
 # what you get back is a type error about CSSResult, or every test in
-# the suite failing to import. Four sessions, three plans. Instant.
+# the suite failing to import. Four sessions, three plans. And a nested
+# rule starting with an element name is dropped by the device's
+# Chrome 113 in silence -- no tier here runs an engine that can see it.
+# Instant.
 .PHONY: css-check
-css-check: ## Fail if a css`` literal was ended early by a backtick in a comment
+css-check: ## Fail on a css`` literal ended early by a backtick, or a nested rule needing an &
 	@cd frontend && node scripts/check-css-literals.mjs
+	@cd frontend && node scripts/check-css-nesting.mjs
 
 # .pi/ and CLAUDE.md document commands, and a doc that documents a
 # command wrongly is worse than no doc: an agent runs it confidently.
@@ -192,15 +197,21 @@ skill-check: ## Fail if the agent docs name a missing make target, or AGENTS.md
 commit-check: ## Fail if a commit subject is not a Conventional Commit
 	@./scripts/commit-check.sh $(if $(RANGE),--range $(RANGE))
 
-# What a merge to main would release, without releasing it.  Reads the
-# same .releaserc.yml CI does, so "why did that not cut a version" is
-# answerable locally instead of by pushing and watching.  Needs no
-# credentials: --dry-run neither tags nor publishes.
+# What running the release workflow now would ship, without shipping it.
+# Reads the same .releaserc.yml CI does, so "why did that not cut a
+# version" is answerable locally instead of by pushing and watching.
+# Needs no credentials: --dry-run neither tags nor publishes.
+#
+# release.yml is dispatch-only, so this answers the question that
+# actually gets asked now -- what has accumulated since the last tag --
+# rather than what one merge would have done.  The workflow's own
+# `dry_run` input is the same answer from the runner, against whatever
+# main points at rather than the working tree.
 #
 # The pins must stay identical to release.yml's, which is where the note
 # on holding the conventionalcommits preset at 9 lives -- at 10 the
 # release notes come out empty with everything green.
-release-dry: ## Print the version a merge to main would release
+release-dry: ## Print the version a release run would cut right now
 	@npx --yes \
 		-p semantic-release@25 \
 		-p @semantic-release/commit-analyzer@13 \

README.md

@@ -106,5 +106,8 @@ make dev          # run with hot-reload
 make build-prod   # produce a release binary
 ```
 
-More detail for contributors lives in
-[`docs/dev/overview.md`](./docs/dev/overview.md) and [`CLAUDE.md`](./CLAUDE.md).
+More detail for contributors lives in [`CLAUDE.md`](./CLAUDE.md) — the
+architecture, the conventions and the reasons behind them. What is
+being worked on is [the issue
+tracker](https://git.ljones.me/yonlu/yellowjacket/issues); #73 is the
+roadmap.

backend/androidlog/android.go

@@ -0,0 +1,55 @@
+//go:build android
+
+// The write itself, and nothing else. Everything decidable off a phone
+// is in androidlog.go; see the package comment for why.
+
+package androidlog
+
+/*
+#cgo LDFLAGS: -llog
+#include <stdlib.h>
+#include <android/log.h>
+*/
+import "C"
+
+import (
+	"log/slog"
+	"unsafe"
+)
+
+// The priorities in androidlog.go are android/log.h's own values, and
+// these are what says so. A constant expression that would be negative
+// does not compile as a uint, so a renumbered header fails the build
+// here rather than logging everything at the wrong severity -- which is
+// the failure that would otherwise be invisible, since logcat would
+// happily print whatever number it was handed.
+const (
+	_ = uint(C.ANDROID_LOG_VERBOSE - PrioVerbose)
+	_ = uint(PrioVerbose - C.ANDROID_LOG_VERBOSE)
+	_ = uint(C.ANDROID_LOG_DEBUG - PrioDebug)
+	_ = uint(PrioDebug - C.ANDROID_LOG_DEBUG)
+	_ = uint(C.ANDROID_LOG_INFO - PrioInfo)
+	_ = uint(PrioInfo - C.ANDROID_LOG_INFO)
+	_ = uint(C.ANDROID_LOG_WARN - PrioWarn)
+	_ = uint(PrioWarn - C.ANDROID_LOG_WARN)
+	_ = uint(C.ANDROID_LOG_ERROR - PrioError)
+	_ = uint(PrioError - C.ANDROID_LOG_ERROR)
+	_ = uint(C.ANDROID_LOG_FATAL - PrioFatal)
+	_ = uint(PrioFatal - C.ANDROID_LOG_FATAL)
+)
+
+// New returns the handler main() installs on Android.
+func New(opts *slog.HandlerOptions) slog.Handler {
+	return NewHandler(opts, write)
+}
+
+// write hands one line to liblog.
+func write(prio int, tag, msg string) {
+	cTag := C.CString(tag)
+	defer C.free(unsafe.Pointer(cTag))
+
+	cMsg := C.CString(msg)
+	defer C.free(unsafe.Pointer(cMsg))
+
+	C.__android_log_write(C.int(prio), cTag, cMsg)
+}

backend/androidlog/androidlog.go

@@ -0,0 +1,250 @@
+// Package androidlog routes slog to logcat.
+//
+// **An Android app's fd 1 and 2 go to /dev/null**, so every line this
+// app writes with slog is discarded on that platform -- including the
+// one naming the error it is about to os.Exit on. #52 is what that
+// cost: a process that vanished with no tombstone, no AndroidRuntime
+// stack and nothing in `logcat -b crash`, at Priority/Critical for
+// months, whose entire diagnosis was one slog.Error main.go was
+// already writing.
+//
+// The platform's own sink is __android_log_write, which is a handful
+// of cgo -- and cgo compiled by nothing `make lint` or `make test`
+// runs, since the only toolchain that builds the android tag is a
+// cross-compiler and the only thing that runs it is a phone. So the
+// split here is the one backend/mediacontrols/androidpayload.go makes,
+// pushed as far as it will go: **everything except the write itself is
+// in this file, untagged**. The priority mapping, the formatting, the
+// chunking and the handler's own attr and group bookkeeping are
+// ordinary Go that `go test` exercises on any platform; android.go is
+// fifteen lines that hand a string to liblog.
+package androidlog
+
+import (
+	"bytes"
+	"context"
+	"log/slog"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+// Tag is what logcat labels these lines with.
+//
+// It is a constant of ours rather than the application id, because the
+// debug build carries `applicationIdSuffix ".dev"` so that it can be
+// installed beside the release app -- so a tag derived from the package
+// name is a *different* tag on the one build that can be inspected, and
+// the filter that is supposed to show these lines would hide them on
+// exactly the build used to look for them.
+const Tag = "yellowjacket"
+
+// Android's priorities, from android/log.h. These are the values
+// __android_log_write takes; android.go asserts at compile time that
+// they still match the header, so a renumbered platform is a build
+// failure here rather than a warning silently logged as an error.
+const (
+	PrioVerbose = 2
+	PrioDebug   = 3
+	PrioInfo    = 4
+	PrioWarn    = 5
+	PrioError   = 6
+	PrioFatal   = 7
+)
+
+// maxPayload is how much of one line liblog will carry.
+//
+// The kernel logger's entry is 4068 bytes for the tag, the message and
+// their two NULs together, and what does not fit is **dropped without
+// comment** -- so a long line would be truncated in the middle of the
+// thing worth reading. 3500 leaves room for the tag and for the "(N/M)"
+// a continuation carries.
+const maxPayload = 3500
+
+// WriteFunc is the platform sink: one already-formatted line, at one
+// priority, under one tag.
+//
+// It is a parameter rather than a package-level function so that the
+// handler can be driven by a test on a machine with no liblog at all.
+type WriteFunc func(prio int, tag, msg string)
+
+// Priority maps a slog level onto an Android one.
+//
+// slog's levels are open -- a caller may define its own at any int --
+// so this is a banding rather than a lookup: anything below Info is
+// debug, anything at or above Error is error. A custom level between
+// two of the standard ones lands in the band beneath it, which is what
+// slog's own level naming does.
+func Priority(level slog.Level) int {
+	switch {
+	case level < slog.LevelDebug:
+		return PrioVerbose
+	case level < slog.LevelInfo:
+		return PrioDebug
+	case level < slog.LevelWarn:
+		return PrioInfo
+	case level < slog.LevelError:
+		return PrioWarn
+	default:
+		return PrioError
+	}
+}
+
+// Handler formats records with slog's own TextHandler and hands each
+// line to a WriteFunc.
+//
+// It delegates the formatting rather than doing it, because WithAttrs
+// and WithGroup are the half of slog.Handler that is easy to get subtly
+// wrong -- and a logger whose groups are wrong is a logger nobody reads.
+// What it does own is what logcat needs and TextHandler does not know
+// about: the priority, and the fact that a line has a maximum length.
+type Handler struct {
+	write WriteFunc
+
+	// mu guards buf, which the delegate writes into. slog.Handler is
+	// documented as safe for concurrent use.
+	mu       *sync.Mutex
+	buf      *bytes.Buffer
+	delegate slog.Handler
+}
+
+// NewHandler builds a handler over an arbitrary sink.
+//
+// The time and the level are dropped from the formatted line: logcat
+// stamps every entry with both, and repeating them costs a quarter of
+// the width of a phone-sized terminal to say the same thing twice.
+func NewHandler(opts *slog.HandlerOptions, write WriteFunc) *Handler {
+	buf := &bytes.Buffer{}
+
+	inner := &slog.HandlerOptions{}
+	if opts != nil {
+		*inner = *opts
+	}
+
+	user := inner.ReplaceAttr
+	inner.ReplaceAttr = func(groups []string, a slog.Attr) slog.Attr {
+		if len(groups) == 0 && isBuiltin(a) {
+			return slog.Attr{}
+		}
+
+		if user != nil {
+			return user(groups, a)
+		}
+
+		return a
+	}
+
+	return &Handler{
+		write:    write,
+		mu:       &sync.Mutex{},
+		buf:      buf,
+		delegate: slog.NewTextHandler(buf, inner),
+	}
+}
+
+// isBuiltin reports whether an attr is slog's own time or level,
+// rather than a caller's attribute that happens to share the name.
+//
+// ReplaceAttr cannot tell those apart by key. It is called with an
+// empty group path for the built-ins *and* for every top-level
+// attribute, so a key comparison alone silently eats a caller's own
+// "level" or "time" -- which is not hypothetical: the probe that
+// verified this package on the device logged one, and the attribute
+// vanished. The kinds are what separate them, because slog builds the
+// built-ins as slog.Any(LevelKey, r.Level) and slog.Time(TimeKey, ...)
+// and an attribute value of type slog.Level is not something a caller
+// passes by accident.
+func isBuiltin(a slog.Attr) bool {
+	switch a.Key {
+	case slog.TimeKey:
+		return a.Value.Kind() == slog.KindTime
+	case slog.LevelKey:
+		_, ok := a.Value.Any().(slog.Level)
+
+		return ok
+	default:
+		return false
+	}
+}
+
+// Enabled reports whether the level is worth formatting.
+func (h *Handler) Enabled(ctx context.Context, level slog.Level) bool {
+	return h.delegate.Enabled(ctx, level)
+}
+
+// Handle formats one record and writes it out, in as many entries as
+// its length demands.
+func (h *Handler) Handle(ctx context.Context, rec slog.Record) error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	h.buf.Reset()
+
+	if err := h.delegate.Handle(ctx, rec); err != nil {
+		return err
+	}
+
+	prio := Priority(rec.Level)
+	for _, line := range Chunk(strings.TrimRight(h.buf.String(), "\n")) {
+		h.write(prio, Tag, line)
+	}
+
+	return nil
+}
+
+// WithAttrs returns a handler carrying the given attributes.
+func (h *Handler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return h.derive(h.delegate.WithAttrs(attrs))
+}
+
+// WithGroup returns a handler that qualifies subsequent attributes.
+func (h *Handler) WithGroup(name string) slog.Handler {
+	return h.derive(h.delegate.WithGroup(name))
+}
+
+// derive shares the buffer and its mutex with the parent.
+//
+// They must be shared rather than copied: the delegate returned by
+// WithAttrs writes into the *same* buffer this one does, so a second
+// mutex would guard nothing and two loggers derived from one would
+// interleave their bytes into a single line.
+func (h *Handler) derive(delegate slog.Handler) *Handler {
+	return &Handler{
+		write:    h.write,
+		mu:       h.mu,
+		buf:      h.buf,
+		delegate: delegate,
+	}
+}
+
+// Chunk splits a formatted record into entries liblog will carry
+// whole.
+//
+// A record short enough to fit is returned as it is, which is nearly
+// every record; the numbering only appears where something was going
+// to be silently truncated anyway. It splits on bytes rather than runes
+// because the limit is a byte count -- a multi-byte rune straddling the
+// boundary is a mojibake character in a log line, against a lost one.
+func Chunk(msg string) []string {
+	if len(msg) <= maxPayload {
+		return []string{msg}
+	}
+
+	var parts []string
+
+	for rest := msg; rest != ""; {
+		n := min(maxPayload, len(rest))
+		parts = append(parts, rest[:n])
+		rest = rest[n:]
+	}
+
+	numbered := make([]string, 0, len(parts))
+	for i, p := range parts {
+		numbered = append(
+			numbered,
+			"("+strconv.Itoa(i+1)+"/"+strconv.Itoa(len(parts))+") "+p,
+		)
+	}
+
+	return numbered
+}

backend/androidlog/androidlog_test.go

@@ -0,0 +1,355 @@
+package androidlog_test
+
+import (
+	"log/slog"
+	"strings"
+	"sync"
+	"testing"
+
+	"yellowjacket/backend/androidlog"
+)
+
+// entry is one call to the sink.
+type entry struct {
+	prio int
+	tag  string
+	msg  string
+}
+
+// recorder is the platform write, on a machine with no platform.
+type recorder struct {
+	mu      sync.Mutex
+	entries []entry
+}
+
+func (r *recorder) write(prio int, tag, msg string) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	r.entries = append(r.entries, entry{prio: prio, tag: tag, msg: msg})
+}
+
+func (r *recorder) only(t *testing.T) entry {
+	t.Helper()
+
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if len(r.entries) != 1 {
+		t.Fatalf("want exactly one entry, got %d: %v", len(r.entries), r.entries)
+	}
+
+	return r.entries[0]
+}
+
+func newLogger(r *recorder, level slog.Level) *slog.Logger {
+	return slog.New(androidlog.NewHandler(
+		&slog.HandlerOptions{Level: level},
+		r.write,
+	))
+}
+
+// TestPriorityMapsEveryLevel pins the level banding.
+//
+// This is the one thing in #160 that a wrong answer hides rather than
+// breaks: logcat prints whatever priority it is handed, so an Error
+// filed as Info is a line that is present, correct and invisible to
+// every filter anyone would use to look for it.
+func TestPriorityMapsEveryLevel(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name  string
+		level slog.Level
+		want  int
+	}{
+		{"below debug is verbose", slog.LevelDebug - 1, androidlog.PrioVerbose},
+		{"debug", slog.LevelDebug, androidlog.PrioDebug},
+		{"info", slog.LevelInfo, androidlog.PrioInfo},
+		{"warn", slog.LevelWarn, androidlog.PrioWarn},
+		{"error", slog.LevelError, androidlog.PrioError},
+
+		// slog's levels are open, so a caller may sit between two of
+		// the named ones.  Each lands in the band beneath it, which is
+		// what slog's own level naming does ("INFO+2").
+		{"between info and warn", slog.LevelInfo + 2, androidlog.PrioInfo},
+		{"between warn and error", slog.LevelWarn + 1, androidlog.PrioWarn},
+		{"above error", slog.LevelError + 4, androidlog.PrioError},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			if got := androidlog.Priority(tt.level); got != tt.want {
+				t.Errorf("Priority(%v) = %d, want %d", tt.level, got, tt.want)
+			}
+		})
+	}
+}
+
+// TestPrioritiesAreTheHeadersValues pins the constants themselves.
+//
+// android.go asserts these against android/log.h at compile time, but
+// only a cross-compiler ever builds that file.  This is the assertion
+// that runs in CI, and the numbers are written out longhand on purpose
+// -- comparing a constant to itself would pass on any renumbering.
+func TestPrioritiesAreTheHeadersValues(t *testing.T) {
+	t.Parallel()
+
+	for _, tt := range []struct {
+		name string
+		got  int
+		want int
+	}{
+		{"verbose", androidlog.PrioVerbose, 2},
+		{"debug", androidlog.PrioDebug, 3},
+		{"info", androidlog.PrioInfo, 4},
+		{"warn", androidlog.PrioWarn, 5},
+		{"error", androidlog.PrioError, 6},
+		{"fatal", androidlog.PrioFatal, 7},
+	} {
+		if tt.got != tt.want {
+			t.Errorf("%s priority = %d, want %d", tt.name, tt.got, tt.want)
+		}
+	}
+}
+
+// TestRecordReachesTheSink is the whole point of the package: a line
+// written with slog arrives, under the app's tag, at the right
+// priority.
+func TestRecordReachesTheSink(t *testing.T) {
+	t.Parallel()
+
+	rec := &recorder{}
+	newLogger(rec, slog.LevelInfo).Error("application error", "err", "boom")
+
+	got := rec.only(t)
+
+	if got.prio != androidlog.PrioError {
+		t.Errorf("priority = %d, want %d", got.prio, androidlog.PrioError)
+	}
+
+	if got.tag != androidlog.Tag {
+		t.Errorf("tag = %q, want %q", got.tag, androidlog.Tag)
+	}
+
+	if !strings.Contains(got.msg, "application error") {
+		t.Errorf("message %q does not carry the message", got.msg)
+	}
+
+	if !strings.Contains(got.msg, `err=boom`) {
+		t.Errorf("message %q does not carry the attribute", got.msg)
+	}
+}
+
+// TestTheTagIsNotTheApplicationID guards the trap the tag exists to
+// avoid.
+//
+// The debug build carries `applicationIdSuffix ".dev"`, so it is
+// installed as app.yellowjacket.dev -- and it is the *only* build whose
+// WebView can be inspected, so it is the build anyone debugging this
+// app is running.  A tag derived from the application id therefore
+// differs between the build being looked at and the build the filter
+// was written for, which is the failure this whole issue is about
+// wearing a different hat.
+func TestTheTagIsNotTheApplicationID(t *testing.T) {
+	t.Parallel()
+
+	if strings.Contains(androidlog.Tag, ".") {
+		t.Errorf(
+			"tag %q looks like an application id; it must be stable "+
+				"across the debug suffix",
+			androidlog.Tag,
+		)
+	}
+
+	// Logcat's tag field is 23 bytes.  A longer one is truncated, and a
+	// truncated tag matches no filter.
+	if len(androidlog.Tag) > 23 {
+		t.Errorf("tag %q is %d bytes, over logcat's 23", androidlog.Tag, len(androidlog.Tag))
+	}
+}
+
+// TestTimeAndLevelAreDropped checks the formatting decision.
+//
+// logcat stamps every entry with a timestamp and a priority letter, so
+// carrying slog's own is the same information twice on a 424px screen.
+func TestTimeAndLevelAreDropped(t *testing.T) {
+	t.Parallel()
+
+	rec := &recorder{}
+	newLogger(rec, slog.LevelInfo).Warn("scan finished", "files", 1577)
+
+	got := rec.only(t).msg
+
+	if strings.Contains(got, "time=") {
+		t.Errorf("message %q still carries a timestamp", got)
+	}
+
+	if strings.Contains(got, "level=") {
+		t.Errorf("message %q still carries a level", got)
+	}
+
+	if !strings.Contains(got, "files=1577") {
+		t.Errorf("message %q lost its attributes with them", got)
+	}
+}
+
+// TestACallersOwnLevelAttrSurvives is a regression, and it was found on
+// the phone rather than here.
+//
+// Dropping slog's built-in time and level by key alone also drops a
+// caller's attribute of the same name, because ReplaceAttr sees an
+// empty group path for both. The probe that verified this package on
+// the device wrote slog.Info("...", "level", "info") and logcat showed
+// the message with no attributes at all.
+func TestACallersOwnLevelAttrSurvives(t *testing.T) {
+	t.Parallel()
+
+	rec := &recorder{}
+	newLogger(rec, slog.LevelInfo).Info("probe", "level", "info", "time", "soon")
+
+	got := rec.only(t).msg
+
+	for _, want := range []string{"level=info", "time=soon"} {
+		if !strings.Contains(got, want) {
+			t.Errorf("message %q lost the caller's %q", got, want)
+		}
+	}
+
+	// And slog's own are still gone: the built-in level renders as a
+	// bare word like INFO, never as the caller's value.
+	if strings.Contains(got, "level=INFO") {
+		t.Errorf("message %q carries slog's own level", got)
+	}
+}
+
+// TestLevelIsHonoured checks that Enabled reaches the delegate.
+func TestLevelIsHonoured(t *testing.T) {
+	t.Parallel()
+
+	rec := &recorder{}
+	log := newLogger(rec, slog.LevelWarn)
+
+	log.Info("not this one")
+	log.Warn("this one")
+
+	if got := rec.only(t).msg; !strings.Contains(got, "this one") {
+		t.Errorf("wrong record survived: %q", got)
+	}
+}
+
+// TestGroupsAndAttrsSurvive covers the half of slog.Handler this
+// delegates rather than implements -- the reason it delegates at all.
+func TestGroupsAndAttrsSurvive(t *testing.T) {
+	t.Parallel()
+
+	rec := &recorder{}
+	log := newLogger(rec, slog.LevelInfo).
+		With("component", "player").
+		WithGroup("track")
+
+	log.Info("loaded", "path", "/sdcard/Music/a.flac")
+
+	got := rec.only(t).msg
+
+	for _, want := range []string{
+		"component=player",
+		"track.path=/sdcard/Music/a.flac",
+	} {
+		if !strings.Contains(got, want) {
+			t.Errorf("message %q is missing %q", got, want)
+		}
+	}
+}
+
+// TestDerivedHandlersDoNotInterleave is why derive shares the buffer's
+// mutex rather than taking a new one.
+//
+// Two loggers derived from one write into the same buffer, so a second
+// mutex would guard nothing and a concurrent pair would splice each
+// other's bytes into a single line -- which reads as corrupted logs
+// under load and as nothing at all in a test that logs once.
+func TestDerivedHandlersDoNotInterleave(t *testing.T) {
+	t.Parallel()
+
+	rec := &recorder{}
+	base := newLogger(rec, slog.LevelInfo)
+
+	var wg sync.WaitGroup
+
+	for i := range 8 {
+		wg.Add(1)
+
+		go func() {
+			defer wg.Done()
+
+			log := base.With("worker", i).WithGroup("g")
+			for range 50 {
+				log.Info("tick", "n", i)
+			}
+		}()
+	}
+
+	wg.Wait()
+
+	rec.mu.Lock()
+	defer rec.mu.Unlock()
+
+	if len(rec.entries) != 8*50 {
+		t.Fatalf("got %d entries, want %d", len(rec.entries), 8*50)
+	}
+
+	for _, e := range rec.entries {
+		if strings.Count(e.msg, "msg=tick") != 1 {
+			t.Fatalf("interleaved line: %q", e.msg)
+		}
+	}
+}
+
+// TestChunkLeavesShortLinesAlone is the common case: no numbering
+// appears on a record that was never going to be truncated.
+func TestChunkLeavesShortLinesAlone(t *testing.T) {
+	t.Parallel()
+
+	got := androidlog.Chunk("msg=short")
+
+	if len(got) != 1 || got[0] != "msg=short" {
+		t.Errorf("Chunk(short) = %q, want the input unchanged", got)
+	}
+}
+
+// TestChunkSplitsWhatWouldBeTruncated covers the case liblog drops
+// silently.
+func TestChunkSplitsWhatWouldBeTruncated(t *testing.T) {
+	t.Parallel()
+
+	const n = 9000
+
+	long := strings.Repeat("x", n)
+	parts := androidlog.Chunk(long)
+
+	if len(parts) < 2 {
+		t.Fatalf("a %d-byte line was not split", n)
+	}
+
+	var payload strings.Builder
+
+	for i, p := range parts {
+		if len(p) > 4000 {
+			t.Errorf("part %d is %d bytes, over liblog's entry", i, len(p))
+		}
+
+		_, rest, found := strings.Cut(p, ") ")
+		if !found {
+			t.Fatalf("part %d carries no (n/m) marker: %q", i, p)
+		}
+
+		payload.WriteString(rest)
+	}
+
+	if payload.String() != long {
+		t.Errorf("the parts do not reassemble into the input")
+	}
+}

backend/autotag/apply.go

@@ -8,6 +8,7 @@ import (
 	"log/slog"
 
 	"yellowjacket/backend/database/sql/sqlcgen"
+	"yellowjacket/backend/tagtotals"
 )
 
 // TagChanges mirrors tagwriter.TagChanges — redefined here so the
@@ -28,6 +29,8 @@ const (
 	FieldYear        = "year"
 	FieldTrackNumber = "track_number"
 	FieldDiscNumber  = "disc_number"
+	FieldTotalTracks = "total_tracks"
+	FieldTotalDiscs  = "total_discs"
 	FieldCoverArt    = "cover_art"
 )
 
@@ -418,5 +421,32 @@ func buildChanges(
 		changes[FieldDiscNumber] = track.DiscNumber
 	}
 
+	// The totals are what says "2 of 10" rather than a bare tick, and
+	// dropping them here is what made autotagging an album *erase* the
+	// evidence: the release becomes MBID-matched while the field
+	// GetAlbumCompleteness reads stays absent.
+	//
+	// They are written unconditionally where the candidate has a
+	// tracklist, not only when they differ from the local value, because
+	// the common case is a file that declares no total at all -- which
+	// compares equal to nothing and would be skipped by a diff guard.
+	if tracks, discs := tagtotals.For(
+		candidatePositions(cand), track.DiscNumber,
+	); tracks > 0 {
+		changes[FieldTotalTracks] = tracks
+		changes[FieldTotalDiscs] = discs
+	}
+
 	return changes
 }
+
+// candidatePositions is the candidate's tracklist as bare positions.
+func candidatePositions(cand Candidate) []tagtotals.Position {
+	out := make([]tagtotals.Position, 0, len(cand.Tracks))
+
+	for _, t := range cand.Tracks {
+		out = append(out, tagtotals.Position{Disc: t.DiscNumber, Track: t.Position})
+	}
+
+	return out
+}

backend/autotag/buildchanges_test.go

@@ -0,0 +1,90 @@
+package autotag
+
+import "testing"
+
+// Autotagging an album used to *erase* the evidence that says "2 of 10":
+// the release became MBID-matched while the totals the files declared
+// went unwritten, so the album page showed a plain tick.  These pin the
+// two halves of the fix that are easy to get wrong silently.
+func TestBuildChanges_Totals(t *testing.T) {
+	t.Parallel()
+
+	twoDiscs := Candidate{
+		Tracks: []CandidateTrack{
+			{DiscNumber: 1, Position: 1},
+			{DiscNumber: 1, Position: 2},
+			{DiscNumber: 2, Position: 1},
+			{DiscNumber: 2, Position: 2},
+			{DiscNumber: 2, Position: 3},
+		},
+	}
+
+	tests := []struct {
+		name       string
+		cand       Candidate
+		local      LocalTrack
+		track      CandidateTrack
+		wantTracks any
+		wantDiscs  any
+	}{
+		{
+			// The common case, and the one a diff guard would skip: the
+			// file declares no total at all, so the total "has not
+			// changed" and would never be written.
+			name: "a file with no total gets one",
+			cand: Candidate{Tracks: []CandidateTrack{
+				{Position: 1}, {Position: 2}, {Position: 3},
+			}},
+			local:      LocalTrack{TrackNumber: 1},
+			track:      CandidateTrack{Position: 1},
+			wantTracks: 3,
+			wantDiscs:  1,
+		},
+		{
+			// 5 here would be the release's track count.  Summed once
+			// per disc by GetAlbumCompleteness that claims a ten-track
+			// expectation for a five-track album, which no library can
+			// ever satisfy.
+			name:       "a multi-disc release totals the track's own disc",
+			cand:       twoDiscs,
+			local:      LocalTrack{},
+			track:      CandidateTrack{DiscNumber: 2, Position: 1},
+			wantTracks: 3,
+			wantDiscs:  2,
+		},
+		{
+			name:       "the other disc gets its own total",
+			cand:       twoDiscs,
+			local:      LocalTrack{},
+			track:      CandidateTrack{DiscNumber: 1, Position: 1},
+			wantTracks: 2,
+			wantDiscs:  2,
+		},
+		{
+			// A candidate with no tracklist knows nothing, and writing
+			// a zero would claim it did.
+			name:       "a candidate with no tracklist writes no total",
+			cand:       Candidate{},
+			local:      LocalTrack{},
+			track:      CandidateTrack{Position: 1},
+			wantTracks: nil,
+			wantDiscs:  nil,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			changes := buildChanges(tc.local, tc.cand, tc.track)
+
+			if got := changes[FieldTotalTracks]; got != tc.wantTracks {
+				t.Errorf("%s: got %v, want %v", FieldTotalTracks, got, tc.wantTracks)
+			}
+
+			if got := changes[FieldTotalDiscs]; got != tc.wantDiscs {
+				t.Errorf("%s: got %v, want %v", FieldTotalDiscs, got, tc.wantDiscs)
+			}
+		})
+	}
+}

backend/autotag/recommend.go

@@ -17,6 +17,34 @@ const (
 	RecommendationStrong Recommendation = "strong"
 )
 
+// ConfidentTier is the tier at which this package considers a match
+// good enough to act on without being asked to look.
+//
+// It exists as a name rather than as `== RecommendationStrong` at
+// each call site because two features read it and they must not
+// disagree about what "high confidence" means: the album page tells
+// the user unprompted that the autotagger has a match (#28), and
+// strict auto-accept will rewrite the files without asking (#90).
+// A page that says "we are sure" about something the auto-accept
+// pass would decline is the app contradicting itself.
+//
+// What the two do *not* share is everything else. Surfacing a match
+// is a suggestion with a confirm dialog behind it; auto-accept is an
+// irreversible on-disk rewrite, and #90 gates it on further
+// conditions this tier cannot express — exact track count, every
+// title matching, lengths within a couple of seconds, no cover
+// replacement, no MBID conflict. So this is the floor both stand on,
+// not the whole of either test.
+const ConfidentTier = RecommendationStrong
+
+// Confident reports whether a tier clears ConfidentTier.
+//
+// A comparison rather than an equality, so adding a tier above
+// "strong" later does not silently stop qualifying.
+func Confident(r Recommendation) bool {
+	return recommendationRank(r) >= recommendationRank(ConfidentTier)
+}
+
 const (
 	// Absolute score tiers.
 	strongScoreThresh = 0.90

backend/autotag/recommend_test.go

@@ -168,3 +168,34 @@ func TestRecommend_LocalCandidatesWithoutRGMBIDCompareByTitle(t *testing.T) {
 		t.Errorf("different-title rival: Recommend = %q, want medium", got)
 	}
 }
+
+// The tier both features stand on is one name, checked here rather
+// than assumed at two call sites.
+//
+// #28 renders "we have a match for this album" on the album page and
+// #90 will rewrite files without asking; a page that claims confidence
+// the auto-accept pass would decline is the app contradicting itself.
+// What they do not share is everything else — auto-accept adds gates
+// this tier cannot express — so this pins the floor, not the whole of
+// either test.
+func TestConfidentIsTheOneSharedFloor(t *testing.T) {
+	t.Parallel()
+
+	if ConfidentTier != RecommendationStrong {
+		t.Errorf("ConfidentTier = %q, want strong", ConfidentTier)
+	}
+
+	for _, tc := range []struct {
+		rec  Recommendation
+		want bool
+	}{
+		{RecommendationNone, false},
+		{RecommendationLow, false},
+		{RecommendationMedium, false},
+		{RecommendationStrong, true},
+	} {
+		if got := Confident(tc.rec); got != tc.want {
+			t.Errorf("Confident(%q) = %v, want %v", tc.rec, got, tc.want)
+		}
+	}
+}

backend/autotagservice/albummatch.go

@@ -0,0 +1,145 @@
+package autotagservice
+
+import (
+	"database/sql"
+	"fmt"
+
+	"yellowjacket/backend/autotag"
+)
+
+// AlbumMatchView is "the autotagger already has a confident match for
+// the album you are looking at".
+//
+// It is deliberately not a score. The album page renders a suggestion,
+// and a suggestion has to be actionable: which release, what it is
+// called, and whether acting on it here would do the whole album or
+// only part of it.
+type AlbumMatchView struct {
+	// GroupKey is the tagging group the actions operate on.
+	GroupKey string `json:"groupKey"`
+
+	// Recommendation is the tier, as a string, for a caller that
+	// wants to render the strength rather than trust the filter.
+	Recommendation string `json:"recommendation"`
+
+	// Score is the top candidate's raw score, 0..1.
+	Score float64 `json:"score"`
+
+	// ReleaseMBID is the release Apply would write.
+	ReleaseMBID string `json:"releaseMbid"`
+
+	// Title and ArtistCredit name that release, so the banner can say
+	// what it is offering rather than "a match".
+	Title        string `json:"title"`
+	ArtistCredit string `json:"artistCredit"`
+
+	// TrackCount is the group's local track count.
+	TrackCount int64 `json:"trackCount"`
+
+	// GroupCount is how many tagging groups this album spans.
+	//
+	// More than one means a multi-disc album (one group per disc), and
+	// it is the reason this is a field rather than an implementation
+	// detail: applying "the album" from a single button would retag
+	// one disc of three and leave the folder holding a mix of old and
+	// new tags. The caller offers review instead.
+	GroupCount int `json:"groupCount"`
+}
+
+// MatchForAlbum answers "does the autotagger have something confident
+// to say about this album", for the album detail page.
+//
+// Three things about it are load-bearing.
+//
+// **It costs no MusicBrainz request.** Everything it needs is already
+// on disk: `tagging_items` carries the top score and release from the
+// background prefetch, and `tagging_candidates` durably holds the
+// scored list. The rate limiters here are shared with every page the
+// user can open, so a lookup that fires on page load must not join
+// that queue — which also means this returns nothing for a folder
+// nobody has scored yet, rather than scoring it now. That is the
+// right trade: the prefetch will get to it, and a page that silently
+// spends a minute of somebody's MusicBrainz budget to draw a banner
+// is worse than a page that says nothing.
+//
+// **The tier is computed, not read.** `tagging_items.score` is the raw
+// number and `Recommend` is what turns it into a claim — capping it
+// for an ambiguous runner-up, an incomplete alignment or a folder too
+// small to corroborate itself. Filtering on the raw score would
+// promise confidence the scorer had explicitly withheld.
+//
+// **Nothing is said about an album the user has already answered
+// for.** Only a `pending` group qualifies: `confirmed` covers both a
+// finished apply and an explicit "leave as is", and `skipped` is the
+// user saying not now. Re-offering either is nagging, and "leave as
+// is" would be actively wrong to argue with.
+func (s *Service) MatchForAlbum(albumID int64) (*AlbumMatchView, error) {
+	if albumID <= 0 {
+		return nil, nil //nolint:nilnil // "no album" is not an error.
+	}
+
+	rows, err := s.db.Queries.GetTaggingItemsForAlbum(
+		s.ctx, sql.NullInt64{Int64: albumID, Valid: true},
+	)
+	if err != nil {
+		return nil, fmt.Errorf("tagging items for album: %w", err)
+	}
+
+	pending := rows[:0:0]
+
+	for _, row := range rows {
+		if row.Status == "pending" {
+			pending = append(pending, row)
+		}
+	}
+
+	if len(pending) == 0 {
+		return nil, nil //nolint:nilnil // nothing to say is not an error.
+	}
+
+	// Rows arrive best-score-first, so the first pending one is the
+	// group worth describing. On a multi-disc album that is one disc
+	// of several and GroupCount says so.
+	best := pending[0]
+
+	cands := s.lookupCachedCandidates(best.GroupKey)
+	if len(cands) == 0 {
+		return nil, nil //nolint:nilnil // not scored yet; see the doc comment.
+	}
+
+	locals, err := s.scorer.LocalTracksForGroup(s.ctx, best.GroupKey)
+	if err != nil {
+		return nil, fmt.Errorf("local tracks for group: %w", err)
+	}
+
+	group := autotag.Group{
+		AlbumName:   best.AlbumName,
+		AlbumArtist: best.AlbumArtist,
+		Tracks:      locals,
+		Synthetic:   best.Synthetic != 0,
+	}
+
+	rec := autotag.Recommend(group, cands)
+	if !autotag.Confident(rec) {
+		return nil, nil //nolint:nilnil // not confident enough to interrupt.
+	}
+
+	top := cands[0]
+
+	// The release the banner names must be the release Apply would
+	// write. Apply with an empty MBID takes the top cached candidate,
+	// which is what this reads — but it is passed explicitly anyway,
+	// so a rescore between the page rendering and the user clicking
+	// cannot swap the album out from under a button they have already
+	// read.
+	return &AlbumMatchView{
+		GroupKey:       best.GroupKey,
+		Recommendation: string(rec),
+		Score:          top.Score,
+		ReleaseMBID:    top.ReleaseMBID,
+		Title:          top.Title,
+		ArtistCredit:   top.ArtistCredit,
+		TrackCount:     best.TrackCount,
+		GroupCount:     len(pending),
+	}, nil
+}

backend/autotagservice/albummatch_test.go

@@ -0,0 +1,320 @@
+package autotagservice
+
+import (
+	"encoding/json"
+	"testing"
+
+	"yellowjacket/backend/autotag"
+	"yellowjacket/backend/database"
+)
+
+// seedAlbumGroup writes one album's files, its tagging item and the
+// durable candidate blob the prefetch would have left behind.
+//
+// The candidate list is what a real one looks like in the two ways
+// that decide the tier: a per-track alignment for every local track,
+// and a runner-up far enough away not to count as ambiguity.
+func seedAlbumGroup(
+	t *testing.T,
+	db *database.DB,
+	groupKey string,
+	tracks int,
+	status string,
+	score float64,
+) int64 {
+	t.Helper()
+
+	for i := 1; i <= tracks; i++ {
+		database.InsertTestTrack(t, db, database.TestTrack{
+			FilePath:    filePathFor(groupKey, i),
+			Title:       titleFor(i),
+			Artist:      "Tideline",
+			Album:       "Glass Harbour",
+			AlbumArtist: "Tideline",
+			TrackNumber: int64(i),
+			LengthMs:    200000,
+			LibraryID:   0,
+			GroupKey:    groupKey,
+		})
+	}
+
+	if _, err := db.ExecContext(`
+		INSERT INTO tagging_items
+		    (group_key, library_id, track_count, album_name, album_artist,
+		     disc_number, status, score, best_match_release_mbid)
+		VALUES (?, 0, ?, 'Glass Harbour', 'Tideline', 0, ?, ?, 'rel-1')
+	`, groupKey, tracks, status, score); err != nil {
+		t.Fatalf("insert tagging item: %v", err)
+	}
+
+	var albumID int64
+	if err := db.QueryRowWriter(
+		`SELECT album_id FROM audio_files WHERE group_key = ? LIMIT 1`, groupKey,
+	).Scan(&albumID); err != nil {
+		t.Fatalf("read album id: %v", err)
+	}
+
+	return albumID
+}
+
+func filePathFor(groupKey string, n int) string {
+	return "/music/" + groupKey + "/0" + string(rune('0'+n)) + ".mp3"
+}
+
+func titleFor(n int) string {
+	return "Track " + string(rune('0'+n))
+}
+
+// storeCandidates writes the durable blob GetCandidates would have
+// cached, with `top` as the winning score.
+func storeCandidates(
+	t *testing.T, db *database.DB, groupKey string, tracks int, top float64,
+) {
+	t.Helper()
+
+	aligns := make([]autotag.TrackAlignment, 0, tracks)
+	for i := range tracks {
+		aligns = append(aligns, autotag.TrackAlignment{
+			Status:     autotag.AlignmentMatched,
+			LocalIndex: i,
+		})
+	}
+
+	cands := []autotag.Candidate{
+		{
+			ReleaseMBID:      "rel-1",
+			ReleaseGroupMBID: "rg-1",
+			Title:            "Glass Harbour",
+			ArtistCredit:     "Tideline",
+			TrackCount:       tracks,
+			Alignments:       aligns,
+			Score:            top,
+		},
+		{
+			ReleaseMBID:      "rel-2",
+			ReleaseGroupMBID: "rg-2",
+			Title:            "Something Else",
+			ArtistCredit:     "Another Band",
+			TrackCount:       tracks,
+			Score:            0.40,
+		},
+	}
+
+	blob, err := json.Marshal(cands)
+	if err != nil {
+		t.Fatalf("marshal candidates: %v", err)
+	}
+
+	if _, err := db.ExecContext(
+		`INSERT INTO tagging_candidates (group_key, candidates) VALUES (?, ?)`,
+		groupKey, string(blob),
+	); err != nil {
+		t.Fatalf("insert candidates: %v", err)
+	}
+}
+
+// A confident match is what the album page exists to surface.
+func TestMatchForAlbumSurfacesAConfidentMatch(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	svc := newTestService(t, db)
+
+	albumID := seedAlbumGroup(t, db, "grp-1", 8, "pending", 0.95)
+	storeCandidates(t, db, "grp-1", 8, 0.95)
+
+	got, err := svc.MatchForAlbum(albumID)
+	if err != nil {
+		t.Fatalf("MatchForAlbum: %v", err)
+	}
+
+	if got == nil {
+		t.Fatal("no match returned for a strong candidate")
+	}
+
+	if got.Recommendation != string(autotag.RecommendationStrong) {
+		t.Errorf("recommendation = %q, want strong", got.Recommendation)
+	}
+
+	// The release named is the release Apply would write — the page
+	// must not offer one album and tag another.
+	if got.ReleaseMBID != "rel-1" || got.Title != "Glass Harbour" {
+		t.Errorf("named %q/%q, want rel-1/Glass Harbour", got.ReleaseMBID, got.Title)
+	}
+
+	if got.GroupCount != 1 {
+		t.Errorf("groupCount = %d, want 1", got.GroupCount)
+	}
+}
+
+// The tier is computed from the candidates, not read off the raw
+// score — a high number the scorer would have capped must not reach
+// the page as confidence it withheld.
+func TestMatchForAlbumDoesNotTrustTheStoredScore(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	svc := newTestService(t, db)
+
+	// Two tracks: below the evidence floor, so `Recommend` caps this
+	// at medium however well it scores.
+	albumID := seedAlbumGroup(t, db, "grp-2", 2, "pending", 0.99)
+	storeCandidates(t, db, "grp-2", 2, 0.99)
+
+	got, err := svc.MatchForAlbum(albumID)
+	if err != nil {
+		t.Fatalf("MatchForAlbum: %v", err)
+	}
+
+	if got != nil {
+		t.Errorf("surfaced %+v for a two-track folder, want nothing", got)
+	}
+}
+
+// A weak match is not worth interrupting for.
+func TestMatchForAlbumStaysQuietBelowTheTier(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	svc := newTestService(t, db)
+
+	albumID := seedAlbumGroup(t, db, "grp-3", 8, "pending", 0.60)
+	storeCandidates(t, db, "grp-3", 8, 0.60)
+
+	got, err := svc.MatchForAlbum(albumID)
+	if err != nil {
+		t.Fatalf("MatchForAlbum: %v", err)
+	}
+
+	if got != nil {
+		t.Errorf("surfaced %+v for a 0.60 match, want nothing", got)
+	}
+}
+
+// An album the user has already answered for is not re-offered.
+//
+// `confirmed` covers both a finished apply and an explicit "leave as
+// is", and arguing with the second would be actively wrong.
+func TestMatchForAlbumRespectsAnAnswerAlreadyGiven(t *testing.T) {
+	t.Parallel()
+
+	for _, status := range []string{"confirmed", "skipped", "matched"} {
+		t.Run(status, func(t *testing.T) {
+			t.Parallel()
+
+			db := database.NewTestDB(t)
+			svc := newTestService(t, db)
+
+			albumID := seedAlbumGroup(t, db, "grp-"+status, 8, status, 0.95)
+			storeCandidates(t, db, "grp-"+status, 8, 0.95)
+
+			got, err := svc.MatchForAlbum(albumID)
+			if err != nil {
+				t.Fatalf("MatchForAlbum: %v", err)
+			}
+
+			if got != nil {
+				t.Errorf("surfaced %+v for a %s group, want nothing", got, status)
+			}
+		})
+	}
+}
+
+// A folder nobody has scored yet says nothing, rather than scoring it
+// now: the MusicBrainz limiter is shared with every page the user can
+// open, and this runs on page load.
+func TestMatchForAlbumMakesNoNetworkCallForAnUnscoredFolder(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	svc := newTestService(t, db)
+
+	// No storeCandidates: the prefetch has not reached this folder.
+	albumID := seedAlbumGroup(t, db, "grp-4", 8, "pending", 0.95)
+
+	got, err := svc.MatchForAlbum(albumID)
+	if err != nil {
+		t.Fatalf("MatchForAlbum: %v", err)
+	}
+
+	if got != nil {
+		t.Errorf("surfaced %+v with no cached candidates, want nothing", got)
+	}
+}
+
+// A multi-disc album is several groups, and the count is what stops
+// the page offering one button that would retag one disc of two.
+func TestMatchForAlbumCountsEveryGroupOfTheAlbum(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	svc := newTestService(t, db)
+
+	albumID := seedAlbumGroup(t, db, "grp-d1", 8, "pending", 0.95)
+	storeCandidates(t, db, "grp-d1", 8, 0.95)
+
+	// Disc two: same album row, its own folder and tagging group.
+	for i := 1; i <= 6; i++ {
+		database.InsertTestTrack(t, db, database.TestTrack{
+			FilePath:    filePathFor("grp-d2", i),
+			Title:       titleFor(i),
+			Artist:      "Tideline",
+			Album:       "Glass Harbour",
+			AlbumArtist: "Tideline",
+			TrackNumber: int64(i),
+			DiscNumber:  2,
+			LengthMs:    200000,
+			LibraryID:   0,
+			GroupKey:    "grp-d2",
+		})
+	}
+
+	if _, err := db.ExecContext(`
+		INSERT INTO tagging_items
+		    (group_key, library_id, track_count, album_name, album_artist,
+		     disc_number, status, score)
+		VALUES ('grp-d2', 0, 6, 'Glass Harbour', 'Tideline', 2, 'pending', 0.93)
+	`); err != nil {
+		t.Fatalf("insert disc two: %v", err)
+	}
+
+	storeCandidates(t, db, "grp-d2", 6, 0.93)
+
+	got, err := svc.MatchForAlbum(albumID)
+	if err != nil {
+		t.Fatalf("MatchForAlbum: %v", err)
+	}
+
+	if got == nil {
+		t.Fatal("no match returned")
+	}
+
+	if got.GroupCount != 2 {
+		t.Errorf("groupCount = %d, want 2", got.GroupCount)
+	}
+
+	// Best-first: the 0.95 disc is the one described.
+	if got.GroupKey != "grp-d1" {
+		t.Errorf("described %q, want the higher-scoring grp-d1", got.GroupKey)
+	}
+}
+
+// An album with no local files at all — a pure catalog page — is not
+// a question this can answer.
+func TestMatchForAlbumSaysNothingWithoutAnAlbum(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	svc := newTestService(t, db)
+
+	for _, id := range []int64{0, -1, 4242} {
+		got, err := svc.MatchForAlbum(id)
+		if err != nil {
+			t.Fatalf("MatchForAlbum(%d): %v", id, err)
+		}
+
+		if got != nil {
+			t.Errorf("MatchForAlbum(%d) = %+v, want nil", id, got)
+		}
+	}
+}

backend/autotagservice/fieldnames_test.go

@@ -0,0 +1,38 @@
+package autotagservice
+
+import (
+	"testing"
+
+	"yellowjacket/backend/autotag"
+	"yellowjacket/backend/tagwriter"
+)
+
+// twAdapter passes the diff map through unchanged, so autotag's field
+// constants and tagwriter's are the same keys written down twice --
+// deliberately, to keep autotag out of the write pipeline's import
+// graph.  A key that drifts does not fail to compile and does not fail
+// to write: the writer simply finds no entry under the name it looks
+// for, and the field is silently dropped.  That is what this pins, and
+// this package is the one place that imports both.
+func TestAutotagAndTagwriterAgreeOnFieldNames(t *testing.T) {
+	t.Parallel()
+
+	pairs := map[string][2]string{
+		"title":        {autotag.FieldTitle, tagwriter.FieldTitle},
+		"artist":       {autotag.FieldArtist, tagwriter.FieldArtist},
+		"album":        {autotag.FieldAlbum, tagwriter.FieldAlbum},
+		"album artist": {autotag.FieldAlbumArtist, tagwriter.FieldAlbumArtist},
+		"year":         {autotag.FieldYear, tagwriter.FieldYear},
+		"track number": {autotag.FieldTrackNumber, tagwriter.FieldTrackNumber},
+		"disc number":  {autotag.FieldDiscNumber, tagwriter.FieldDiscNumber},
+		"total tracks": {autotag.FieldTotalTracks, tagwriter.FieldTotalTracks},
+		"total discs":  {autotag.FieldTotalDiscs, tagwriter.FieldTotalDiscs},
+		"cover art":    {autotag.FieldCoverArt, tagwriter.FieldCoverArt},
+	}
+
+	for name, pair := range pairs {
+		if pair[0] != pair[1] {
+			t.Errorf("%s: autotag says %q, tagwriter says %q", name, pair[0], pair[1])
+		}
+	}
+}

backend/config/config.go

@@ -544,7 +544,7 @@ func (c *Config) SetDefaultPage(page string) error {
 		c.General.ApplyDefaults()
 	}
 
-	c.General.DefaultPage = DefaultPage(page)
+	c.General.DefaultPage = View(page)
 
 	if err := c.General.Validate(); err != nil {
 		return fmt.Errorf(
@@ -666,6 +666,124 @@ func (c *Config) SetAllowMeteredCatalogDownload(allow bool) error {
 	return nil
 }
 
+// GetPopupVolume reports whether the bottom bar's volume control is a
+// click-to-open popup rather than an inline slider (#42).
+func (c *Config) GetPopupVolume() bool {
+	if c.General == nil {
+		return false
+	}
+
+	return c.General.PopupVolume
+}
+
+// SetPopupVolume saves the volume control's presentation.
+//
+// Nothing to validate: both values are legal at every width, and the
+// frontend additionally stands the inline slider down below the phone
+// breakpoint whatever this says, because that is about room rather than
+// about preference.
+func (c *Config) SetPopupVolume(popup bool) error {
+	if c.General == nil {
+		c.General = &GeneralConfig{}
+		c.General.ApplyDefaults()
+	}
+
+	c.General.PopupVolume = popup
+
+	if err := c.Save(); err != nil {
+		return fmt.Errorf(
+			"could not save config: %w", err,
+		)
+	}
+
+	events.Emit(
+		c.ctx,
+		events.GeneralConfigChanged,
+		map[string]any{
+			"PopupVolume": popup,
+		},
+	)
+
+	c.logger.Info("volume control presentation updated", "popup", popup)
+
+	return nil
+}
+
+// GetViewVisibility reports which primary views the sidebar should
+// show, answered for every known view rather than only the ones the
+// config mentions -- so the frontend filters on a value and never has
+// to hold a second copy of the defaults.
+func (c *Config) GetViewVisibility() map[string]bool {
+	if c.General == nil {
+		general := &GeneralConfig{}
+		general.ApplyDefaults()
+
+		return general.ResolvedViewVisibility()
+	}
+
+	return c.General.ResolvedViewVisibility()
+}
+
+// SetViewVisible shows or hides one primary view.
+//
+// Two refusals, both about a state the user cannot get out of from the
+// UI they would be left with: Settings is never hideable, and the
+// launch page is never hideable while it is the launch page (change it
+// first). Hiding a view does not make it unreachable -- `navigate`
+// still resolves it, which detail views depend on -- it only takes the
+// nav item away.
+func (c *Config) SetViewVisible(view string, visible bool) error {
+	spec, known := LookupView(view)
+	if !known {
+		return fmt.Errorf("%w: %q", errUnknownView, view)
+	}
+
+	if c.General == nil {
+		c.General = &GeneralConfig{}
+		c.General.ApplyDefaults()
+	}
+
+	if !visible {
+		if !spec.Hideable {
+			return fmt.Errorf("%w: %q", errViewNotHideable, view)
+		}
+
+		if spec.ID == c.General.DefaultPage {
+			return fmt.Errorf("%w: %q", errViewIsLaunchPage, view)
+		}
+	}
+
+	if c.General.ViewVisibility == nil {
+		c.General.ViewVisibility = make(map[string]bool, len(Views))
+	}
+
+	c.General.ViewVisibility[view] = visible
+
+	if err := c.General.Validate(); err != nil {
+		return fmt.Errorf("invalid view visibility: %w", err)
+	}
+
+	if err := c.Save(); err != nil {
+		return fmt.Errorf("could not save config: %w", err)
+	}
+
+	events.Emit(
+		c.ctx,
+		events.GeneralConfigChanged,
+		map[string]any{
+			"ViewVisibility": c.General.ResolvedViewVisibility(),
+		},
+	)
+
+	c.logger.Info(
+		"view visibility updated",
+		"view", view,
+		"visible", visible,
+	)
+
+	return nil
+}
+
 // GetTrackListColumns returns the configured track-list columns.
 func (c *Config) GetTrackListColumns() []tracklist.Column {
 	if c.TrackList == nil {

backend/config/emit_test.go

@@ -188,3 +188,43 @@ func TestEmit_FavoritesChangeCarriesFullConfig(t *testing.T) {
 		}
 	}
 }
+
+// TestEmit_PopupVolumeRoundTripsAndDefaultsToInline pins both halves of
+// #42's storage decision.
+//
+// The **default** is the load-bearing one: inline is what a fresh
+// install and an existing `config.toml` with no such key must both
+// produce, which is why the field names the popup rather than the
+// inline slider. A flag spelled the other way round would default to
+// false, hand every existing install the popup this issue exists to
+// stop being the only option, and need a migration to say otherwise.
+func TestEmit_PopupVolumeRoundTripsAndDefaultsToInline(t *testing.T) {
+	t.Parallel()
+
+	conf, rec := setupRecordedConfig(t)
+
+	if conf.GetPopupVolume() {
+		t.Error("a config with no PopupVolume key wants the popup, want inline")
+	}
+
+	if err := conf.SetPopupVolume(true); err != nil {
+		t.Fatalf("SetPopupVolume: %v", err)
+	}
+
+	if !conf.GetPopupVolume() {
+		t.Error("GetPopupVolume = false after setting it true")
+	}
+
+	data := payloadMap(t, rec, events.GeneralConfigChanged)
+	if data["PopupVolume"] != true {
+		t.Errorf("PopupVolume = %v, want true", data["PopupVolume"])
+	}
+
+	if err := conf.SetPopupVolume(false); err != nil {
+		t.Fatalf("SetPopupVolume(false): %v", err)
+	}
+
+	if conf.GetPopupVolume() {
+		t.Error("GetPopupVolume = true after setting it false")
+	}
+}

backend/config/general.go

@@ -5,27 +5,13 @@ import (
 	"fmt"
 )
 
-// DefaultPage identifies which view the app opens to on launch.
-type DefaultPage string
-
-// Valid DefaultPage values, matching the frontend's top-level route ids.
-const (
-	DefaultPageHome      DefaultPage = "home"
-	DefaultPageTracks    DefaultPage = "tracks"
-	DefaultPageAlbums    DefaultPage = "albums"
-	DefaultPageArtists   DefaultPage = "artists"
-	DefaultPageGenres    DefaultPage = "genres"
-	DefaultPagePlaylists DefaultPage = "playlists"
-	DefaultPageExplore   DefaultPage = "explore"
-	DefaultPageDownloads DefaultPage = "downloads"
-	DefaultPageAutotag   DefaultPage = "autotag"
-	DefaultPageJobs      DefaultPage = "jobs"
-)
-
 // DefaultDefaultPage is the launch page for a fresh install.
-const DefaultDefaultPage = DefaultPageHome
+const DefaultDefaultPage = ViewHome
 
-var errUnknownDefaultPage = errors.New("unknown default page")
+var (
+	errUnknownDefaultPage = errors.New("unknown default page")
+	errViewCannotLaunch   = errors.New("view cannot be the launch page")
+)
 
 // QueueFallback identifies what plays, if anything, once the queue
 // runs out with nothing left to auto-advance to.
@@ -46,18 +32,52 @@ var errUnknownQueueFallback = errors.New("unknown queue fallback")
 // GeneralConfig holds general application preferences that don't
 // belong to a more specific subsystem.
 type GeneralConfig struct {
-	DefaultPage   DefaultPage   `toml:"DefaultPage"`
+	DefaultPage   View          `toml:"DefaultPage"`
 	QueueFallback QueueFallback `toml:"QueueFallback"`
+	// ViewVisibility says which sidebar destinations are shown, keyed by
+	// view id.
+	//
+	// **An absent key means that view's own default** (`Views`), and that
+	// is the whole reason this is a map rather than a `HiddenViews
+	// []string` or a struct of booleans. A list's zero value is "hide
+	// nothing", which cannot express Autotag being off by default without
+	// a migration; a struct field for a view that later stops existing is
+	// stored garbage somebody has to deprecate. Here a view added later
+	// gets its own default rather than being invisible or forcibly
+	// visible, an unknown key is dropped on load, and no install needs
+	// migrating in either direction. Same polarity rule as
+	// AllowMeteredCatalogDownload: the zero value is the intended answer.
+	ViewVisibility map[string]bool `toml:"ViewVisibility"`
 	// AllowMeteredCatalogDownload permits the ~0.6 GB Explore catalog to
 	// be fetched on a connection the platform calls cellular. It defaults
 	// to false, which is the whole point: the zero value is the safe one,
 	// so an existing config with no such key refuses by default rather
 	// than needing a migration to become careful.
 	AllowMeteredCatalogDownload bool `toml:"AllowMeteredCatalogDownload"`
+	// PopupVolume draws the bottom bar's volume as a click-to-open popup
+	// instead of a slider that is always there (#42).
+	//
+	// The polarity is the rule this file already states twice: **the
+	// zero value is the intended answer**. Inline is the new default, so
+	// the flag has to name the *other* choice — an `InlineVolume bool`
+	// would default to false and give every existing install the popup
+	// this issue exists to stop being the only option, and would need a
+	// migration to say otherwise.
+	PopupVolume bool `toml:"PopupVolume"`
 }
 
 // ApplyDefaults fills zero-value fields with sensible defaults.
+//
+// A launch page naming a *retired* view is treated as a zero value
+// rather than as an error, because the alternative is an app that will
+// not start for anyone who had that page selected when it was removed.
+// An unknown-but-not-retired name still fails Validate: that is a typo,
+// and telling someone about it is the useful answer.
 func (c *GeneralConfig) ApplyDefaults() {
+	if _, retired := RetiredViews[c.DefaultPage]; retired {
+		c.DefaultPage = ""
+	}
+
 	if c.DefaultPage == "" {
 		c.DefaultPage = DefaultDefaultPage
 	}
@@ -71,15 +91,17 @@ func (c *GeneralConfig) ApplyDefaults() {
 func (c *GeneralConfig) Validate() error {
 	c.ApplyDefaults()
 
-	switch c.DefaultPage {
-	case DefaultPageHome, DefaultPageTracks, DefaultPageAlbums, DefaultPageArtists,
-		DefaultPageGenres, DefaultPagePlaylists, DefaultPageExplore, DefaultPageDownloads,
-		DefaultPageAutotag, DefaultPageJobs:
-		// Valid.
-	default:
+	spec, known := LookupView(string(c.DefaultPage))
+	if !known {
 		return fmt.Errorf("%w: %q", errUnknownDefaultPage, c.DefaultPage)
 	}
 
+	if !spec.CanLaunch {
+		return fmt.Errorf("%w: %q", errViewCannotLaunch, c.DefaultPage)
+	}
+
+	c.normalizeViewVisibility()
+
 	switch c.QueueFallback {
 	case QueueFallbackStop, QueueFallbackFavorites, QueueFallbackDynamicMix:
 		// Valid.
@@ -89,3 +111,51 @@ func (c *GeneralConfig) Validate() error {
 
 	return nil
 }
+
+// normalizeViewVisibility drops what the stored map may not say, and
+// repairs the one invariant the shell depends on.
+//
+// Three things are dropped or forced, and all three are reachable only
+// from a hand-edited config or from a version that knew different
+// views: an unknown id (a view removed since, e.g. when #27 folds Jobs
+// into Settings) says nothing to anybody; a view that is not Hideable
+// cannot be false; and **the launch page is always visible**, because
+// otherwise an install lands on a page with no nav item pointing at it.
+//
+// That last one is a *repair* here and an *error* at the setter
+// (SetViewVisible), deliberately. On load there is nobody to tell and
+// the honest reading of "my launch page is Autotag" is that this user
+// wants Autotag, so it is un-hidden rather than the launch page being
+// silently reset to something they did not choose. At the setter the
+// user is right there and can act, so it refuses and says why.
+func (c *GeneralConfig) normalizeViewVisibility() {
+	for id := range c.ViewVisibility {
+		spec, known := LookupView(id)
+		if !known || !spec.Hideable {
+			delete(c.ViewVisibility, id)
+		}
+	}
+
+	if visible, ok := c.ViewVisibility[string(c.DefaultPage)]; ok && !visible {
+		c.ViewVisibility[string(c.DefaultPage)] = true
+	}
+}
+
+// ResolvedViewVisibility answers for every known view, so no caller has
+// to know the defaults -- the frontend included, which is why the
+// binding returns this rather than the stored map.
+func (c *GeneralConfig) ResolvedViewVisibility() map[string]bool {
+	resolved := make(map[string]bool, len(Views))
+
+	for _, v := range Views {
+		visible := v.VisibleByDefault
+
+		if stored, ok := c.ViewVisibility[string(v.ID)]; ok && v.Hideable {
+			visible = stored
+		}
+
+		resolved[string(v.ID)] = visible
+	}
+
+	return resolved
+}

backend/config/views.go

@@ -0,0 +1,103 @@
+package config
+
+import "errors"
+
+var (
+	errUnknownView      = errors.New("unknown view")
+	errViewNotHideable  = errors.New("view cannot be hidden")
+	errViewIsLaunchPage = errors.New("view is the launch page")
+)
+
+// View identifies one of the shell's primary destinations -- the
+// things the sidebar lists and `index.ts` knows as `VIEW_TAGS`.
+type View string
+
+// The primary views, in no particular order: the sidebar owns the order
+// it draws them in, because that is presentation.
+const (
+	ViewHome      View = "home"
+	ViewPlaylists View = "playlists"
+	ViewArtists   View = "artists"
+	ViewGenres    View = "genres"
+	ViewAlbums    View = "albums"
+	ViewTracks    View = "tracks"
+	ViewExplore   View = "explore"
+	ViewDownloads View = "downloads"
+	ViewAutotag   View = "autotag"
+	ViewSettings  View = "settings"
+)
+
+// RetiredViews are destinations that used to exist and no longer do.
+//
+// A *visibility* entry for a removed view needs no such list: it is a
+// key in a map, and an unknown key is dropped on load. A `DefaultPage`
+// is a **value**, and an unknown one fails validation -- which on the
+// load path means the app refuses to start rather than a setting being
+// ignored. So the one shape that cannot be retired for free is named
+// here and reset to the default instead.
+//
+// `jobs` was folded into Settings by #27: library scans under
+// Libraries, index work under Search Index, downloads under the
+// download clients, and the autotag apply into the Autotag view.
+var RetiredViews = map[View]struct{}{
+	"jobs": {},
+}
+
+// ViewSpec is what the backend knows about a destination. The label and
+// the icon are deliberately absent: those are presentation, they live
+// beside the rest of the app's icon vocabulary in
+// `frontend/src/utils/icon-language.ts`, and a Go copy of them would be
+// a second thing to keep in step for nothing.
+type ViewSpec struct {
+	// ID is the view name the frontend navigates by.
+	ID View
+	// VisibleByDefault is what an install gets when the config says
+	// nothing about this view -- which is every install until somebody
+	// changes it, and every view added after this one shipped.
+	VisibleByDefault bool
+	// Hideable is false for Settings alone. It is a property of the
+	// view rather than a check in the setter because `config.toml` is
+	// hand-editable, and an app that can be locked out of its own
+	// Settings by a typo is a support problem nobody can debug
+	// remotely.
+	Hideable bool
+	// CanLaunch reports whether the view may be the launch page.
+	// Settings is the only one that may not, which is the shape the
+	// DefaultPage enum already had.
+	CanLaunch bool
+}
+
+// Views is the one list of primary destinations, in the order Settings
+// offers them.
+//
+// It is the single source for three things that used to be written down
+// separately: which views exist, which of them may be the launch page
+// (`DefaultPage`'s validation reads it), and what an unconfigured
+// install shows.
+//
+// Autotag is the one view hidden by default: it rewrites tags on disk,
+// which is not what most libraries want on day one, and #25 asks for it
+// to be turned on deliberately.
+var Views = []ViewSpec{
+	{ID: ViewHome, VisibleByDefault: true, Hideable: true, CanLaunch: true},
+	{ID: ViewPlaylists, VisibleByDefault: true, Hideable: true, CanLaunch: true},
+	{ID: ViewArtists, VisibleByDefault: true, Hideable: true, CanLaunch: true},
+	{ID: ViewGenres, VisibleByDefault: true, Hideable: true, CanLaunch: true},
+	{ID: ViewAlbums, VisibleByDefault: true, Hideable: true, CanLaunch: true},
+	{ID: ViewTracks, VisibleByDefault: true, Hideable: true, CanLaunch: true},
+	{ID: ViewExplore, VisibleByDefault: true, Hideable: true, CanLaunch: true},
+	{ID: ViewDownloads, VisibleByDefault: true, Hideable: true, CanLaunch: true},
+	{ID: ViewAutotag, VisibleByDefault: false, Hideable: true, CanLaunch: true},
+	{ID: ViewSettings, VisibleByDefault: true, Hideable: false, CanLaunch: false},
+}
+
+// LookupView returns the spec for a view id.
+func LookupView(id string) (ViewSpec, bool) {
+	for _, v := range Views {
+		if string(v.ID) == id {
+			return v, true
+		}
+	}
+
+	return ViewSpec{}, false
+}

backend/config/views_test.go

@@ -0,0 +1,307 @@
+package config
+
+import (
+	"errors"
+	"log/slog"
+	"path/filepath"
+	"testing"
+)
+
+// newViewTestConfig builds a Config backed by a temp file, which is all
+// SetViewVisible needs: it saves and emits, and the emit is a no-op
+// without a running app.
+func newViewTestConfig(t *testing.T) *Config {
+	t.Helper()
+
+	c := &Config{
+		logger:   slog.Default(),
+		filePath: filepath.Join(t.TempDir(), "config.toml"),
+	}
+
+	// Load a file that is not there: that is what marks the config
+	// loaded, without which Save refuses on the *second* write.
+	if err := c.Load(); err != nil {
+		t.Fatalf("Load() error: %v", err)
+	}
+
+	return c
+}
+
+// A view the config says nothing about takes its own default, which is
+// what makes this need no migration in either direction: an existing
+// install gets Autotag hidden without a key, and a view added later
+// gets its own answer rather than the list's.
+func TestViewVisibilityDefaults(t *testing.T) {
+	t.Parallel()
+
+	general := &GeneralConfig{}
+	general.ApplyDefaults()
+
+	resolved := general.ResolvedViewVisibility()
+
+	if len(resolved) != len(Views) {
+		t.Fatalf("resolved %d views, want %d", len(resolved), len(Views))
+	}
+
+	if resolved[string(ViewAutotag)] {
+		t.Error("autotag should be hidden by default")
+	}
+
+	for _, v := range Views {
+		if v.ID == ViewAutotag {
+			continue
+		}
+
+		if !resolved[string(v.ID)] {
+			t.Errorf("%s should be visible by default", v.ID)
+		}
+	}
+}
+
+// A stored answer wins over the default, in both directions -- turning
+// Autotag on is the whole user-facing point.
+func TestViewVisibilityStoredWins(t *testing.T) {
+	t.Parallel()
+
+	general := &GeneralConfig{
+		ViewVisibility: map[string]bool{
+			string(ViewAutotag): true,
+			string(ViewExplore): false,
+		},
+	}
+	general.ApplyDefaults()
+
+	resolved := general.ResolvedViewVisibility()
+
+	if !resolved[string(ViewAutotag)] {
+		t.Error("autotag was switched on and should be visible")
+	}
+
+	if resolved[string(ViewExplore)] {
+		t.Error("explore was switched off and should be hidden")
+	}
+}
+
+// A key for a view that no longer exists is discarded rather than
+// migrated. This is the property the #25-before-#27 ordering rests on:
+// when Jobs folds into Settings, `jobs = true` in somebody's config is
+// a key nothing asks about, not a cleanup task.
+func TestValidateDropsUnknownAndUnhideableViews(t *testing.T) {
+	t.Parallel()
+
+	general := &GeneralConfig{
+		ViewVisibility: map[string]bool{
+			"a-view-that-was-removed": true,
+			string(ViewSettings):      false,
+			string(ViewAutotag):       true,
+		},
+	}
+
+	if err := general.Validate(); err != nil {
+		t.Fatalf("Validate() error: %v", err)
+	}
+
+	if _, ok := general.ViewVisibility["a-view-that-was-removed"]; ok {
+		t.Error("an unknown view id should be dropped on load")
+	}
+
+	if _, ok := general.ViewVisibility[string(ViewSettings)]; ok {
+		t.Error("settings is not hideable and should not be stored")
+	}
+
+	if !general.ResolvedViewVisibility()[string(ViewSettings)] {
+		t.Error("settings must resolve visible whatever the file said")
+	}
+}
+
+// On load there is nobody to tell, so a launch page hidden by a
+// hand-edited file is un-hidden rather than the launch page being
+// reset to something the user did not choose.
+func TestValidateRevealsAHiddenLaunchPage(t *testing.T) {
+	t.Parallel()
+
+	general := &GeneralConfig{
+		DefaultPage: ViewAutotag,
+		ViewVisibility: map[string]bool{
+			string(ViewAutotag): false,
+		},
+	}
+
+	if err := general.Validate(); err != nil {
+		t.Fatalf("Validate() error: %v", err)
+	}
+
+	if !general.ResolvedViewVisibility()[string(ViewAutotag)] {
+		t.Error("the launch page must be visible")
+	}
+}
+
+// A launch page naming a view that no longer exists resets to the
+// default instead of failing validation, which on the load path would
+// mean the app refusing to start for whoever had it selected.
+//
+// This is the one shape #25's storage decision does *not* make free: a
+// visibility entry is a key and an unknown key is dropped, but a launch
+// page is a value.
+func TestARetiredLaunchPageFallsBackToTheDefault(t *testing.T) {
+	t.Parallel()
+
+	general := &GeneralConfig{DefaultPage: "jobs"}
+
+	if err := general.Validate(); err != nil {
+		t.Fatalf("Validate() error: %v", err)
+	}
+
+	if general.DefaultPage != DefaultDefaultPage {
+		t.Errorf("DefaultPage = %q, want %q", general.DefaultPage, DefaultDefaultPage)
+	}
+}
+
+// A name that is merely wrong is still an error: that is a typo, and
+// saying so is more useful than ignoring it.
+func TestAnUnknownLaunchPageIsStillAnError(t *testing.T) {
+	t.Parallel()
+
+	general := &GeneralConfig{DefaultPage: "nonsense"}
+
+	if err := general.Validate(); !errors.Is(err, errUnknownDefaultPage) {
+		t.Fatalf("Validate() error = %v, want errUnknownDefaultPage", err)
+	}
+}
+
+// A retired view is not a view, so nothing offers it and nothing
+// resolves it -- the visibility map included.
+func TestARetiredViewIsGone(t *testing.T) {
+	t.Parallel()
+
+	for id := range RetiredViews {
+		if _, ok := LookupView(string(id)); ok {
+			t.Errorf("%s is retired but still in Views", id)
+		}
+
+		general := &GeneralConfig{}
+		general.ApplyDefaults()
+
+		if _, ok := general.ResolvedViewVisibility()[string(id)]; ok {
+			t.Errorf("%s is retired but still resolves a visibility", id)
+		}
+	}
+}
+
+// Settings may not be the launch page, which is the shape the old
+// DefaultPage enum had and is now read off the same table.
+func TestValidateRejectsAnUnlaunchablePage(t *testing.T) {
+	t.Parallel()
+
+	general := &GeneralConfig{DefaultPage: ViewSettings}
+
+	err := general.Validate()
+	if !errors.Is(err, errViewCannotLaunch) {
+		t.Fatalf("Validate() error = %v, want errViewCannotLaunch", err)
+	}
+}
+
+// At the setter the user is present and can act, so the two states
+// they could not get out of are refused rather than repaired.
+func TestSetViewVisibleRefusals(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		view    string
+		visible bool
+		want    error
+	}{
+		{"settings is never hideable", string(ViewSettings), false, errViewNotHideable},
+		{"the launch page is not hideable", string(ViewHome), false, errViewIsLaunchPage},
+		{"an unknown view is not a setting", "nonsense", false, errUnknownView},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			c := newViewTestConfig(t)
+
+			err := c.SetViewVisible(tt.view, tt.visible)
+			if !errors.Is(err, tt.want) {
+				t.Fatalf("SetViewVisible() error = %v, want %v", err, tt.want)
+			}
+		})
+	}
+}
+
+// Showing a view is never refused, including Settings and the launch
+// page -- there is no state to be stuck in.
+func TestSetViewVisibleShowsAnything(t *testing.T) {
+	t.Parallel()
+
+	c := newViewTestConfig(t)
+
+	for _, v := range Views {
+		if err := c.SetViewVisible(string(v.ID), true); err != nil {
+			t.Fatalf("SetViewVisible(%q, true) error: %v", v.ID, err)
+		}
+	}
+
+	if !c.GetViewVisibility()[string(ViewAutotag)] {
+		t.Error("autotag was switched on and should be visible")
+	}
+}
+
+// The stored map survives a save/load round trip, which is what a
+// map-valued TOML key is worth checking for.
+func TestViewVisibilityRoundTrips(t *testing.T) {
+	t.Parallel()
+
+	path := filepath.Join(t.TempDir(), "config.toml")
+
+	original := &Config{logger: slog.Default(), filePath: path}
+	if err := original.Load(); err != nil {
+		t.Fatalf("Load() error: %v", err)
+	}
+
+	if err := original.SetViewVisible(string(ViewAutotag), true); err != nil {
+		t.Fatalf("SetViewVisible() error: %v", err)
+	}
+
+	if err := original.SetViewVisible(string(ViewExplore), false); err != nil {
+		t.Fatalf("SetViewVisible() error: %v", err)
+	}
+
+	loaded := &Config{logger: slog.Default(), filePath: path}
+	if err := loaded.Load(); err != nil {
+		t.Fatalf("Load() error: %v", err)
+	}
+
+	resolved := loaded.GetViewVisibility()
+
+	if !resolved[string(ViewAutotag)] {
+		t.Error("autotag should have loaded as visible")
+	}
+
+	if resolved[string(ViewExplore)] {
+		t.Error("explore should have loaded as hidden")
+	}
+}
+
+// Every view the shell can launch into is a view the sidebar can show,
+// or an install could land on a page with no nav item and no setting
+// pointing at it.
+func TestEveryLaunchableViewIsAView(t *testing.T) {
+	t.Parallel()
+
+	for _, v := range Views {
+		if !v.CanLaunch {
+			continue
+		}
+
+		if !v.Hideable {
+			continue
+		}
+
+		if _, ok := LookupView(string(v.ID)); !ok {
+			t.Errorf("%s is launchable but not a known view", v.ID)
+		}
+	}
+}

backend/config/window.go

@@ -13,13 +13,31 @@ const (
 	// enforces this at runtime; it is also the floor below which a
 	// reported size is treated as bogus and not persisted.
 	//
-	// 800x600 is where the shell was measured to still work, rather
-	// than a round number: below ~780 the header's subtitle wraps and
-	// pushes the title out of the 4em top bar, and below ~600 tall the
-	// eleven sidebar items no longer fit at once.  The previous
-	// 512x384 was aspirational — at 700x480 the sidebar overflowed
-	// behind the player bar with no scroll and Settings and Jobs could
-	// not be reached at all.
+	// **Both reasons this comment used to give have expired**, and the
+	// value is right for a third one.  It said the floor was 800x600
+	// because "below ~780 the header's subtitle wraps and pushes the
+	// title out of the 4em top bar" and "below ~600 tall the eleven
+	// sidebar items no longer fit at once".  Neither mechanism can
+	// happen now: the subtitle is display:none from 899px down
+	// (index.css), and the sidebar host is overflow-y:auto — measured
+	// at 600x460, its scrollHeight is 434 against a 332px client and
+	// Settings is reachable after scrolling.  A floor defended by two
+	// mechanisms that no longer exist is a number nobody can argue
+	// with, which is worse than either answer.
+	//
+	// It stays 800x600 because that is where the *desktop* chrome
+	// stops being comfortable — the Compact band of plan 018's size
+	// matrix (#24) — and not because the app breaks below it.  It does
+	// not: under 600px wide the phone layout takes over (bottom-nav,
+	// no sidebar) and the shell fits 320px exactly, which is what
+	// makes this a comfort floor rather than a correctness one, and
+	// why a very small window reflows instead of becoming a
+	// mini-player (#12 is a second always-on-top window, not a mode of
+	// this one).
+	//
+	// The previous 512x384 was aspirational — at 700x480 the sidebar
+	// overflowed behind the player bar with no scroll and Settings and
+	// Jobs could not be reached at all.
 	MinWidth = 800
 	// MinHeight is the smallest allowed window height in pixels.
 	MinHeight = 600

backend/database/sql/queries/albums.sql

@@ -40,7 +40,8 @@ WHERE id = ? AND (mbid IS NULL OR mbid = '');
 -- name: GetAlbumsWithPendingReleaseMBID :many
 SELECT id, pending_release_mbid FROM albums
 WHERE pending_release_mbid IS NOT NULL AND pending_release_mbid != ''
-  AND (mbid IS NULL OR mbid = '');
+  AND (mbid IS NULL OR mbid = '')
+LIMIT ?;
 
 -- name: DeleteAlbum :exec
 DELETE FROM albums WHERE id = ?;
@@ -135,3 +136,49 @@ SELECT
     ) AS INTEGER) AS known
 FROM audio_files a
 WHERE a.album_id = sqlc.arg(album_id);
+
+-- name: GetAlbumsCompleteness :many
+-- The same question as GetAlbumCompleteness, asked of a screenful of
+-- albums at once.
+--
+-- A card grid cannot afford one query per card, and the answer it wants
+-- is the one thing a badge cannot guess: an album held 9 tracks of 12
+-- must show the count, never a bare tick.  So this is one query for the
+-- whole grid, asked only of the cards that have a local album id.
+--
+-- It is two grouping levels rather than the single-album form's
+-- correlated subqueries, because a correlated subquery in the FROM
+-- clause is not something SQLite will reliably do -- and because the
+-- slice may only be spelled once, or sqlc expands it twice with
+-- independently numbered placeholders.
+--
+-- The per-disc level is where the meaning is, and it is the same
+-- meaning as the single-album query.  `owned` counts DISTINCT track
+-- numbers within a disc (this app detects duplicates, and counting two
+-- files of track 3 twice would report a short album as complete), with
+-- a file that declares no track number falling back to its own id
+-- because three untagged files are three tracks and not one.
+-- `expected` takes each disc's declared total and sums over discs,
+-- since a total is declared per disc and a release total written on
+-- every file of a two-disc album would double its expectation.  A disc
+-- whose files declared nothing contributes a NULL that SUM ignores,
+-- and `known` is what says the album is therefore unanswerable.
+WITH per_disc AS (
+    SELECT
+        album_id AS album_id,
+        COUNT(DISTINCT COALESCE(CAST(track_number AS TEXT), 'f' || id))
+            AS owned_on_disc,
+        MAX(total_tracks) AS disc_total,
+        SUM(CASE WHEN total_tracks IS NULL THEN 1 ELSE 0 END)
+            AS discs_without_a_total
+    FROM audio_files
+    WHERE album_id IN (sqlc.slice('album_ids'))
+    GROUP BY album_id, COALESCE(disc_number, 1)
+)
+SELECT
+    CAST(album_id AS INTEGER) AS album_id,
+    CAST(SUM(owned_on_disc) AS INTEGER) AS owned,
+    CAST(COALESCE(SUM(disc_total), 0) AS INTEGER) AS expected,
+    CAST(SUM(discs_without_a_total) = 0 AS INTEGER) AS known
+FROM per_disc
+GROUP BY album_id;

backend/database/sql/queries/tagging_items.sql

@@ -342,3 +342,35 @@ WHERE ti.status = 'pending'
   )
 ORDER BY ti.group_key
 LIMIT 1;
+
+-- name: GetTaggingItemsForAlbum :many
+-- Every tagging group holding a file of this album.
+--
+-- The join is `audio_files.group_key`, not a key derived from the
+-- album's folder path: a group carved out of a mixed-bag folder by
+-- SplitMixedFolder is keyed on its tags rather than on a directory,
+-- so a path-derived key finds nothing for exactly the messiest
+-- libraries this is meant to help.
+--
+-- Usually one row. A multi-disc album is one group per disc, which
+-- the caller has to know about rather than average over -- applying
+-- to "the album" would silently retag one disc of three.
+SELECT
+  ti.group_key,
+  ti.status,
+  ti.score,
+  ti.best_match_release_mbid,
+  ti.track_count,
+  ti.album_name,
+  ti.album_artist,
+  ti.synthetic
+FROM tagging_items ti
+WHERE ti.group_key IN (
+    SELECT DISTINCT af.group_key
+    FROM audio_files af
+    WHERE af.album_id = sqlc.arg(album_id) AND af.group_key != ''
+  )
+  AND ti.cleared_at IS NULL
+-- Best first, with an unscored group last rather than first: NULL
+-- sorts low in SQLite and DESC would put it at the top.
+ORDER BY ti.score IS NULL, ti.score DESC, ti.group_key;

backend/database/sql/sqlcgen/albums.sql.go

@@ -8,6 +8,7 @@ package sqlcgen
 import (
 	"context"
 	"database/sql"
+	"strings"
 )
 
 const deleteAlbum = `-- name: DeleteAlbum :exec
@@ -234,10 +235,103 @@ func (q *Queries) GetAlbumsByArtistName(ctx context.Context, arg GetAlbumsByArti
 	return items, nil
 }
 
+const getAlbumsCompleteness = `-- name: GetAlbumsCompleteness :many
+WITH per_disc AS (
+    SELECT
+        album_id AS album_id,
+        COUNT(DISTINCT COALESCE(CAST(track_number AS TEXT), 'f' || id))
+            AS owned_on_disc,
+        MAX(total_tracks) AS disc_total,
+        SUM(CASE WHEN total_tracks IS NULL THEN 1 ELSE 0 END)
+            AS discs_without_a_total
+    FROM audio_files
+    WHERE album_id IN (/*SLICE:album_ids*/?)
+    GROUP BY album_id, COALESCE(disc_number, 1)
+)
+SELECT
+    CAST(album_id AS INTEGER) AS album_id,
+    CAST(SUM(owned_on_disc) AS INTEGER) AS owned,
+    CAST(COALESCE(SUM(disc_total), 0) AS INTEGER) AS expected,
+    CAST(SUM(discs_without_a_total) = 0 AS INTEGER) AS known
+FROM per_disc
+GROUP BY album_id
+`
+
+type GetAlbumsCompletenessRow struct {
+	AlbumID  int64
+	Owned    int64
+	Expected int64
+	Known    int64
+}
+
+// The same question as GetAlbumCompleteness, asked of a screenful of
+// albums at once.
+//
+// A card grid cannot afford one query per card, and the answer it wants
+// is the one thing a badge cannot guess: an album held 9 tracks of 12
+// must show the count, never a bare tick.  So this is one query for the
+// whole grid, asked only of the cards that have a local album id.
+//
+// It is two grouping levels rather than the single-album form's
+// correlated subqueries, because a correlated subquery in the FROM
+// clause is not something SQLite will reliably do -- and because the
+// slice may only be spelled once, or sqlc expands it twice with
+// independently numbered placeholders.
+//
+// The per-disc level is where the meaning is, and it is the same
+// meaning as the single-album query.  `owned` counts DISTINCT track
+// numbers within a disc (this app detects duplicates, and counting two
+// files of track 3 twice would report a short album as complete), with
+// a file that declares no track number falling back to its own id
+// because three untagged files are three tracks and not one.
+// `expected` takes each disc's declared total and sums over discs,
+// since a total is declared per disc and a release total written on
+// every file of a two-disc album would double its expectation.  A disc
+// whose files declared nothing contributes a NULL that SUM ignores,
+// and `known` is what says the album is therefore unanswerable.
+func (q *Queries) GetAlbumsCompleteness(ctx context.Context, albumIds []sql.NullInt64) ([]GetAlbumsCompletenessRow, error) {
+	query := getAlbumsCompleteness
+	var queryParams []interface{}
+	if len(albumIds) > 0 {
+		for _, v := range albumIds {
+			queryParams = append(queryParams, v)
+		}
+		query = strings.Replace(query, "/*SLICE:album_ids*/?", strings.Repeat(",?", len(albumIds))[1:], 1)
+	} else {
+		query = strings.Replace(query, "/*SLICE:album_ids*/?", "NULL", 1)
+	}
+	rows, err := q.db.QueryContext(ctx, query, queryParams...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []GetAlbumsCompletenessRow
+	for rows.Next() {
+		var i GetAlbumsCompletenessRow
+		if err := rows.Scan(
+			&i.AlbumID,
+			&i.Owned,
+			&i.Expected,
+			&i.Known,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const getAlbumsWithPendingReleaseMBID = `-- name: GetAlbumsWithPendingReleaseMBID :many
 SELECT id, pending_release_mbid FROM albums
 WHERE pending_release_mbid IS NOT NULL AND pending_release_mbid != ''
   AND (mbid IS NULL OR mbid = '')
+LIMIT ?
 `
 
 type GetAlbumsWithPendingReleaseMBIDRow struct {
@@ -245,8 +339,8 @@ type GetAlbumsWithPendingReleaseMBIDRow struct {
 	PendingReleaseMbid sql.NullString
 }
 
-func (q *Queries) GetAlbumsWithPendingReleaseMBID(ctx context.Context) ([]GetAlbumsWithPendingReleaseMBIDRow, error) {
-	rows, err := q.db.QueryContext(ctx, getAlbumsWithPendingReleaseMBID)
+func (q *Queries) GetAlbumsWithPendingReleaseMBID(ctx context.Context, limit int64) ([]GetAlbumsWithPendingReleaseMBIDRow, error) {
+	rows, err := q.db.QueryContext(ctx, getAlbumsWithPendingReleaseMBID, limit)
 	if err != nil {
 		return nil, err
 	}

backend/database/sql/sqlcgen/tagging_items.sql.go

@@ -231,6 +231,82 @@ func (q *Queries) GetTaggingItem(ctx context.Context, groupKey string) (TaggingI
 	return i, err
 }
 
+const getTaggingItemsForAlbum = `-- name: GetTaggingItemsForAlbum :many
+SELECT
+  ti.group_key,
+  ti.status,
+  ti.score,
+  ti.best_match_release_mbid,
+  ti.track_count,
+  ti.album_name,
+  ti.album_artist,
+  ti.synthetic
+FROM tagging_items ti
+WHERE ti.group_key IN (
+    SELECT DISTINCT af.group_key
+    FROM audio_files af
+    WHERE af.album_id = ?1 AND af.group_key != ''
+  )
+  AND ti.cleared_at IS NULL
+ORDER BY ti.score IS NULL, ti.score DESC, ti.group_key
+`
+
+type GetTaggingItemsForAlbumRow struct {
+	GroupKey             string
+	Status               string
+	Score                sql.NullFloat64
+	BestMatchReleaseMbid sql.NullString
+	TrackCount           int64
+	AlbumName            string
+	AlbumArtist          string
+	Synthetic            int64
+}
+
+// Every tagging group holding a file of this album.
+//
+// The join is `audio_files.group_key`, not a key derived from the
+// album's folder path: a group carved out of a mixed-bag folder by
+// SplitMixedFolder is keyed on its tags rather than on a directory,
+// so a path-derived key finds nothing for exactly the messiest
+// libraries this is meant to help.
+//
+// Usually one row. A multi-disc album is one group per disc, which
+// the caller has to know about rather than average over -- applying
+// to "the album" would silently retag one disc of three.
+// Best first, with an unscored group last rather than first: NULL
+// sorts low in SQLite and DESC would put it at the top.
+func (q *Queries) GetTaggingItemsForAlbum(ctx context.Context, albumID sql.NullInt64) ([]GetTaggingItemsForAlbumRow, error) {
+	rows, err := q.db.QueryContext(ctx, getTaggingItemsForAlbum, albumID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []GetTaggingItemsForAlbumRow
+	for rows.Next() {
+		var i GetTaggingItemsForAlbumRow
+		if err := rows.Scan(
+			&i.GroupKey,
+			&i.Status,
+			&i.Score,
+			&i.BestMatchReleaseMbid,
+			&i.TrackCount,
+			&i.AlbumName,
+			&i.AlbumArtist,
+			&i.Synthetic,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const listAudioFilesInTaggingGroup = `-- name: ListAudioFilesInTaggingGroup :many
 SELECT
   af.id,

backend/download/importer.go

@@ -12,6 +12,7 @@ import (
 	"strconv"
 	"strings"
 
+	"yellowjacket/backend/tagtotals"
 	"yellowjacket/backend/tagwriter"
 )
 
@@ -275,6 +276,25 @@ func (i *Importer) tagFile(p plannedFile, dl Download) error {
 		changes[tagwriter.FieldDiscNumber] = p.Track.DiscNumber
 	}
 
+	// An imported file should arrive knowing how much of the album it
+	// is one of, or the album reads as "in your library" from its first
+	// imported track onward.
+	//
+	// A *track* download is the case this must not touch: a
+	// RecordingMBID anchor resolves Expected to exactly that one track,
+	// so totalling it would write "1 of 1" onto a track off a
+	// twelve-track album -- a confident lie, and one that outranks the
+	// catalog's own total, which is the fallback that would otherwise
+	// have answered correctly.
+	if dl.RecordingMBID == "" {
+		if tracks, discs := tagtotals.For(
+			expectedPositions(dl.Expected), p.Track.DiscNumber,
+		); tracks > 0 {
+			changes[tagwriter.FieldTotalTracks] = tracks
+			changes[tagwriter.FieldTotalDiscs] = discs
+		}
+	}
+
 	if err := i.tags.WriteUntrackedFileTags(p.Source, changes); err != nil {
 		return fmt.Errorf("write tags: %w", err)
 	}
@@ -282,6 +302,18 @@ func (i *Importer) tagFile(p plannedFile, dl Download) error {
 	return nil
 }
 
+// expectedPositions is the download's resolved tracklist as bare
+// positions.
+func expectedPositions(expected []ExpectedTrack) []tagtotals.Position {
+	out := make([]tagtotals.Position, 0, len(expected))
+
+	for _, t := range expected {
+		out = append(out, tagtotals.Position{Disc: t.DiscNumber, Track: t.Position})
+	}
+
+	return out
+}
+
 // destinationFor computes a file's library path from the template.
 func (i *Importer) destinationFor(
 	p plannedFile,

backend/download/importer_test.go

@@ -446,3 +446,77 @@ func keysOf(m map[string]tagwriter.TagChanges) []string {
 
 	return out
 }
+
+// An imported album should arrive knowing its own size, or the album
+// page reads "in your library" from its first imported track onward --
+// which is the badge complaint this exists to answer.
+func TestImportWritesTheAlbumTotals(t *testing.T) {
+	t.Parallel()
+
+	f := newImportFixture(t,
+		"01 - Airbag.flac",
+		"02 - Paranoid Android.flac",
+		"03 - Subterranean Homesick Alien.flac",
+		"04 - Exit Music (For a Film).flac",
+	)
+
+	if _, err := f.importer.Import(
+		context.Background(),
+		fourTrackDownload(),
+		Result{Dir: f.dir, Files: f.files},
+		ImportOptions{LibraryRoot: f.root, WriteTags: true},
+	); err != nil {
+		t.Fatalf("Import: %v", err)
+	}
+
+	changes := f.tags.writes["01 - Airbag.flac"]
+	if changes == nil {
+		t.Fatal("no tag write recorded for the first track")
+	}
+
+	if got := changes[tagwriter.FieldTotalTracks]; got != 4 {
+		t.Errorf("%s: got %v, want 4", tagwriter.FieldTotalTracks, got)
+	}
+
+	if got := changes[tagwriter.FieldTotalDiscs]; got != 1 {
+		t.Errorf("%s: got %v, want 1", tagwriter.FieldTotalDiscs, got)
+	}
+}
+
+// A RecordingMBID anchor resolves Expected to exactly the one track it
+// asked for, so totalling it would tag a track off a twelve-track album
+// as "1 of 1" -- worse than saying nothing, because a declared total
+// outranks the catalog total that would have answered correctly.
+func TestImportWritesNoTotalsForATrackDownload(t *testing.T) {
+	t.Parallel()
+
+	f := newImportFixture(t, "01 - Airbag.flac")
+
+	dl := Download{
+		ID:            "dl-track",
+		LibraryID:     1,
+		RecordingMBID: "mbid-recording",
+		Artist:        "Radiohead",
+		Album:         "OK Computer",
+		Expected:      []ExpectedTrack{{Position: 1, Title: "Airbag"}},
+	}
+
+	if _, err := f.importer.Import(
+		context.Background(),
+		dl,
+		Result{Dir: f.dir, Files: f.files},
+		ImportOptions{LibraryRoot: f.root, WriteTags: true},
+	); err != nil {
+		t.Fatalf("Import: %v", err)
+	}
+
+	changes := f.tags.writes["01 - Airbag.flac"]
+	if changes == nil {
+		t.Fatal("no tag write recorded")
+	}
+
+	if _, ok := changes[tagwriter.FieldTotalTracks]; ok {
+		t.Errorf("%s written for a single-track download: %v",
+			tagwriter.FieldTotalTracks, changes[tagwriter.FieldTotalTracks])
+	}
+}

backend/download/reconcile.go

@@ -310,6 +310,25 @@ func (r *Reconciler) run(ctx context.Context, force bool) (Summary, error) {
 
 	summary.Synced = r.syncExternalLists(ctx)
 
+	// Nothing is searched for when there is nothing to search with, and
+	// the point is what that *does not* do to the list.
+	//
+	// Attempting anyway is not merely wasted work: every request comes
+	// back "no download clients are enabled", which RecordAttempt writes
+	// down as an attempt and schedules a retry for -- so a user who has
+	// deliberately built a wanted list with no client watched their
+	// requests accrue failures and announce "next check in 6 hours"
+	// about a check that cannot happen. Wanting something without a way
+	// to fetch it is a supported thing to do; being told it is being
+	// looked for is a lie.
+	//
+	// Everything above this line still runs: an artist subscription
+	// still expands, and a request the user satisfied by some other
+	// route -- ripped, bought, copied in -- is still retired, because
+	// neither needs a provider.
+	summary.NoProviders = len(r.manager.enabledProviders()) == 0
+
+	if !summary.NoProviders {
 		attempted, started, err := r.attemptDue(ctx, force)
 		if err != nil {
 			return summary, err
@@ -317,8 +336,9 @@ func (r *Reconciler) run(ctx context.Context, force bool) (Summary, error) {
 
 		summary.Attempted = attempted
 		summary.Started = started
+	}
+
 	summary.Waiting = r.countWaiting(ctx)
-	summary.NoProviders = len(r.manager.enabledProviders()) == 0
 
 	r.logger.Info(
 		"reconciled request list",

backend/download/reconcile_test.go

@@ -453,6 +453,15 @@ func TestReconcileRespectsBatchSize(t *testing.T) {
 	f := newReconcileFixture(t)
 	ctx := context.Background()
 
+	// A client that searches and finds nothing. The batch size is about
+	// how many requests one pass *searches for*, which only means
+	// anything when there is something to search with -- a pass with no
+	// provider now attempts nothing at all, deliberately.
+	f.manager.installProvider(
+		Config{ID: 1, Priority: 50},
+		NewFakeProvider(1, "finds-nothing", Caps{CanSearch: true}),
+	)
+
 	f.reconciler.SetBatch(2)
 
 	for _, mbid := range []string{"rg-1", "rg-2", "rg-3", "rg-4"} {
@@ -593,3 +602,72 @@ func TestSummaryReportsNoProviders(t *testing.T) {
 		t.Error("summary did not report that no download client is enabled")
 	}
 }
+
+// ...and it does not search, which is the part the user sees.
+//
+// Attempting with no provider fails every request with "no download
+// clients are enabled", and RecordAttempt writes that down as an
+// attempt and schedules a retry -- so a wanted list built deliberately
+// without a client accrued failures and announced "next check in 6
+// hours" about a check that cannot happen. Wanting something with no
+// way to fetch it is supported; being told it is being looked for is
+// a lie.
+func TestNoProvidersMeansNoAttempt(t *testing.T) {
+	t.Parallel()
+
+	f := newReconcileFixture(t)
+	ctx := context.Background()
+
+	id, err := f.store.AddRequest(ctx, Request{
+		MBID:      "rg-1",
+		Entity:    EntityReleaseGroup,
+		LibraryID: 1,
+		Title:     "OK Computer",
+	})
+	if err != nil {
+		t.Fatalf("AddRequest: %v", err)
+	}
+
+	f.catalog.tracklists["rg-1"] = fourTrackDownload().Expected
+
+	summary, err := f.reconciler.RunNow(ctx)
+	if err != nil {
+		t.Fatalf("RunNow: %v", err)
+	}
+
+	if summary.Attempted != 0 {
+		t.Errorf("attempted %d requests with no client to search with, want 0",
+			summary.Attempted)
+	}
+
+	// The list still knows what is on it: "nothing happened" has to be
+	// reportable as "nothing was searched for, of the one thing you
+	// want" rather than as silence.
+	if summary.Waiting != 1 {
+		t.Errorf("summary reported %d waiting, want 1", summary.Waiting)
+	}
+
+	req, err := f.store.GetRequest(ctx, id)
+	if err != nil {
+		t.Fatalf("GetRequest: %v", err)
+	}
+
+	if req.Attempts != 0 {
+		t.Errorf("attempts = %d, want 0: a pass that could not search did not",
+			req.Attempts)
+	}
+
+	if req.LastError != "" {
+		t.Errorf("lastError = %q, want empty: the request did not fail, it "+
+			"was never tried", req.LastError)
+	}
+
+	// A new request is due immediately (next_try_at is set to now on
+	// insert), so the fault is not the presence of a time -- it is a
+	// time pushed into the future by a failed attempt, which is what the
+	// UI renders as "next check in 6 hours".
+	if req.NextTryAt.After(time.Now().Add(time.Minute)) {
+		t.Errorf("next try scheduled for %v: a check that cannot happen was "+
+			"put on the clock", req.NextTryAt)
+	}
+}

backend/explore/explore.go

@@ -2,6 +2,7 @@ package explore
 
 import (
 	"context"
+	"database/sql"
 	"log/slog"
 	"math"
 	"sort"
@@ -12,6 +13,7 @@ import (
 	"golang.org/x/sync/singleflight"
 
 	"yellowjacket/backend/database"
+	"yellowjacket/backend/database/sql/sqlcgen"
 	"yellowjacket/backend/events"
 	"yellowjacket/backend/jobs"
 )
@@ -279,37 +281,32 @@ func (e *Service) BackfillReleaseGroupMBIDs() {
 	go e.backfillReleaseGroupMBIDs(e.ctx)
 }
 
-func (e *Service) backfillReleaseGroupMBIDs(ctx context.Context) {
-	rows, err := e.db.QueryContext(
-		"SELECT id, pending_release_mbid FROM release_groups "+
-			"WHERE (mbid IS NULL OR mbid = '') "+
-			"AND pending_release_mbid IS NOT NULL AND pending_release_mbid != '' "+
-			"LIMIT ?",
-		releaseGroupMBIDBackfillMaxPerRun,
+// pendingReleaseMBIDs is the albums this pass has work to do on.
+//
+// It is separate from the pass, and returns its error rather than
+// logging it, so that a test can assert the statement runs against the
+// real schema. That is not a general preference -- it is this
+// statement's history: it named `release_groups`, a table plan 013
+// renamed to `albums`, so it failed on every launch since e7748f1 and
+// the pass returned quietly having done nothing. A test of the pass
+// as a whole cannot see that, because a query error and an empty
+// library are the same early return.
+func (e *Service) pendingReleaseMBIDs(
+	ctx context.Context,
+) ([]sqlcgen.GetAlbumsWithPendingReleaseMBIDRow, error) {
+	return e.db.ReadQueries.GetAlbumsWithPendingReleaseMBID(
+		ctx, releaseGroupMBIDBackfillMaxPerRun,
 	)
+}
+
+func (e *Service) backfillReleaseGroupMBIDs(ctx context.Context) {
+	pending, err := e.pendingReleaseMBIDs(ctx)
 	if err != nil {
 		e.logger.Warn("release-group mbid backfill: query failed", "error", err)
 
 		return
 	}
 
-	type pendingRow struct {
-		id          int64
-		releaseMBID string
-	}
-
-	var pending []pendingRow
-
-	for rows.Next() {
-		var p pendingRow
-
-		if err := rows.Scan(&p.id, &p.releaseMBID); err == nil {
-			pending = append(pending, p)
-		}
-	}
-
-	_ = rows.Close()
-
 	if len(pending) == 0 {
 		return
 	}
@@ -335,7 +332,7 @@ func (e *Service) backfillReleaseGroupMBIDs(ctx context.Context) {
 
 		job.progress(i, len(pending))
 
-		release, err := e.mb.LookupRelease(ctx, p.releaseMBID)
+		release, err := e.mb.LookupRelease(ctx, p.PendingReleaseMbid.String)
 		if err != nil || release.ReleaseGroupMBID == "" {
 			// Left alone rather than cleared: LookupRelease caches its
 			// answer (success or a release with no group) for 7 days,
@@ -344,12 +341,19 @@ func (e *Service) backfillReleaseGroupMBIDs(ctx context.Context) {
 			continue
 		}
 
-		_, err = e.db.ExecContext(
-			"UPDATE release_groups SET mbid = ?, pending_release_mbid = NULL "+
-				"WHERE id = ? AND (mbid IS NULL OR mbid = '')",
-			release.ReleaseGroupMBID, p.id,
-		)
-		if err != nil {
+		// The writer, not ReadQueries: an UPDATE issued on the
+		// query-only pool fails at runtime with "attempt to write a
+		// readonly database".
+		if err := e.db.Queries.ResolveAlbumPendingReleaseMBID(
+			ctx,
+			sqlcgen.ResolveAlbumPendingReleaseMBIDParams{
+				Mbid: sql.NullString{
+					String: release.ReleaseGroupMBID,
+					Valid:  true,
+				},
+				ID: p.ID,
+			},
+		); err != nil {
 			e.logger.Warn("release-group mbid backfill: update failed", "error", err)
 		}
 	}
@@ -2212,6 +2216,7 @@ func (e *Service) gatherTopCandidates(
 				ArtistType: a.Type,
 				Country:    a.Country,
 				InLibrary:  a.InLibrary,
+				LocalID:    a.LocalID,
 			},
 			category:     "artist",
 			qualityScore: quality,
@@ -2243,6 +2248,7 @@ func (e *Service) gatherTopCandidates(
 				ArtistType: a.Type,
 				Country:    a.Country,
 				InLibrary:  a.InLibrary,
+				LocalID:    a.LocalID,
 			},
 			category:     "artist",
 			qualityScore: quality,
@@ -2275,6 +2281,7 @@ func (e *Service) gatherTopCandidates(
 				PrimaryType:  rg.PrimaryType,
 				Year:         year,
 				InLibrary:    rg.InLibrary,
+				LocalID:      rg.LocalID,
 			},
 			category:     "release_group",
 			qualityScore: quality,
@@ -2320,6 +2327,7 @@ func (e *Service) gatherTopCandidates(
 				PrimaryType:  rg.PrimaryType,
 				Year:         year,
 				InLibrary:    rg.InLibrary,
+				LocalID:      rg.LocalID,
 			},
 			category:     "release_group",
 			qualityScore: quality,
@@ -2347,6 +2355,7 @@ func (e *Service) gatherTopCandidates(
 				CAAReleaseMBID: r.CAAReleaseMBID,
 				ReleaseName:    r.ReleaseName,
 				InLibrary:      r.InLibrary,
+				LocalID:        r.LocalID,
 			},
 			category:     "recording",
 			qualityScore: quality,
@@ -2403,6 +2412,7 @@ func (e *Service) gatherTopCandidates(
 				CAAReleaseMBID: r.CAAReleaseMBID,
 				ReleaseName:    r.ReleaseName,
 				InLibrary:      r.InLibrary,
+				LocalID:        r.LocalID,
 			},
 			category:     "recording",
 			qualityScore: quality,
@@ -2425,6 +2435,7 @@ func (e *Service) gatherTopCandidates(
 					ArtistType: m.ArtistType,
 					Country:    m.Country,
 					InLibrary:  m.InLibrary || m.LocalArtistID > 0,
+					LocalID:    m.LocalArtistID,
 				},
 				category:     "artist",
 				qualityScore: quality,
@@ -2445,6 +2456,7 @@ func (e *Service) gatherTopCandidates(
 					PrimaryType:  m.PrimaryType,
 					Year:         year,
 					InLibrary:    m.InLibrary || m.LocalReleaseGroupID > 0,
+					LocalID:      m.LocalReleaseGroupID,
 				},
 				category:     "release_group",
 				qualityScore: quality,
@@ -2459,6 +2471,7 @@ func (e *Service) gatherTopCandidates(
 					ArtistMBID:   m.ArtistMBID,
 					Length:       m.Duration,
 					InLibrary:    m.InLibrary || m.LocalRecordingID > 0,
+					LocalID:      m.LocalRecordingID,
 				},
 				category:     "recording",
 				qualityScore: quality,

backend/explore/pendingreleasembid_test.go

@@ -0,0 +1,250 @@
+package explore
+
+import (
+	"database/sql"
+	"log/slog"
+	"strconv"
+	"testing"
+
+	"yellowjacket/backend/database"
+	"yellowjacket/backend/database/sql/sqlcgen"
+)
+
+// The release-group MBID backfill queried `release_groups`, a table
+// plan 013 renamed to `albums`, so it failed on its first statement on
+// every launch from e7748f1 until #189 -- and the pass swallowed that,
+// because a query error and an empty library are the same early
+// return. Nothing noticed for two reasons worth keeping in mind:
+//
+//   - the statement was **raw SQL**, so sqlc never read it. Every other
+//     statement in the repo was renamed by the same change because sqlc
+//     reads sql/schemas/ and cannot generate against a table that is not
+//     declared. The two sqlc queries this now calls were written by 013
+//     and left uncalled.
+//   - it needs no network and no fixture library to reproduce. The
+//     failure is at prepare time.
+
+// seedPendingAlbum inserts an album whose files carried a release MBID
+// but no release-group MBID, which is what `library.updateMBIDs`
+// leaves behind for this pass to resolve.
+func seedPendingAlbum(
+	t *testing.T,
+	db *database.DB,
+	name, pendingMBID string,
+) int64 {
+	t.Helper()
+
+	res, err := db.ExecContext(
+		"INSERT INTO albums (name, artist_credit, pending_release_mbid) "+
+			"VALUES (?, ?, ?)",
+		name, "Test Artist", pendingMBID,
+	)
+	if err != nil {
+		t.Fatalf("insert albums row: %v", err)
+	}
+
+	id, err := res.LastInsertId()
+	if err != nil {
+		t.Fatalf("last insert id: %v", err)
+	}
+
+	return id
+}
+
+func newPendingTestService(db *database.DB) *Service {
+	return &Service{db: db, logger: slog.Default()}
+}
+
+// TestPendingReleaseMBIDsRunsAgainstTheRealSchema is the regression.
+//
+// It asserts the statement *runs*, which is the whole of what was
+// broken: against the old raw SQL this returns
+// "no such table: release_groups" rather than a row.
+func TestPendingReleaseMBIDsRunsAgainstTheRealSchema(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	e := newPendingTestService(db)
+
+	want := seedPendingAlbum(t, db, "Pending Album", "release-mbid-1")
+
+	pending, err := e.pendingReleaseMBIDs(db.Ctx)
+	if err != nil {
+		t.Fatalf("the backfill's query failed: %v", err)
+	}
+
+	if len(pending) != 1 {
+		t.Fatalf("got %d pending albums, want 1", len(pending))
+	}
+
+	if pending[0].ID != want {
+		t.Errorf("got album id %d, want %d", pending[0].ID, want)
+	}
+
+	if got := pending[0].PendingReleaseMbid.String; got != "release-mbid-1" {
+		t.Errorf("got pending mbid %q, want %q", got, "release-mbid-1")
+	}
+}
+
+// TestOnlyUnresolvedAlbumsAreReturned pins the two conditions that make
+// the pass idempotent, since between them they are what stops it doing
+// the same MusicBrainz lookups on every launch forever.
+func TestOnlyUnresolvedAlbumsAreReturned(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	e := newPendingTestService(db)
+
+	pendingID := seedPendingAlbum(t, db, "Still Pending", "release-mbid-1")
+
+	// Already resolved: it has a real MBID, so there is nothing to
+	// look up even though a marker is still sitting on it.
+	resolved := seedPendingAlbum(t, db, "Already Resolved", "release-mbid-2")
+	if err := db.Queries.SetAlbumMBID(db.Ctx, sqlcgen.SetAlbumMBIDParams{
+		Mbid: sql.NullString{String: "rg-mbid", Valid: true},
+		ID:   resolved,
+	}); err != nil {
+		t.Fatalf("set album mbid: %v", err)
+	}
+
+	// Never had a release MBID to resolve in the first place, which is
+	// most of a library.
+	seedPendingAlbum(t, db, "Nothing Pending", "")
+
+	pending, err := e.pendingReleaseMBIDs(db.Ctx)
+	if err != nil {
+		t.Fatalf("the backfill's query failed: %v", err)
+	}
+
+	if len(pending) != 1 || pending[0].ID != pendingID {
+		t.Fatalf(
+			"got %d albums %v, want only the unresolved one (%d)",
+			len(pending), pending, pendingID,
+		)
+	}
+}
+
+// TestResolvingClearsTheMarker is the other half: once the lookup has
+// answered, the album must stop being a candidate, or the pass repeats
+// the same live MusicBrainz call on every launch.
+func TestResolvingClearsTheMarker(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	e := newPendingTestService(db)
+
+	id := seedPendingAlbum(t, db, "Pending Album", "release-mbid-1")
+
+	// The writer, deliberately: this is an UPDATE, and the read pool
+	// would refuse it at runtime.
+	if err := db.Queries.ResolveAlbumPendingReleaseMBID(
+		db.Ctx,
+		sqlcgen.ResolveAlbumPendingReleaseMBIDParams{
+			Mbid: sql.NullString{String: "resolved-rg-mbid", Valid: true},
+			ID:   id,
+		},
+	); err != nil {
+		t.Fatalf("resolve pending release mbid: %v", err)
+	}
+
+	pending, err := e.pendingReleaseMBIDs(db.Ctx)
+	if err != nil {
+		t.Fatalf("the backfill's query failed: %v", err)
+	}
+
+	if len(pending) != 0 {
+		t.Fatalf("a resolved album is still a candidate: %v", pending)
+	}
+
+	album, err := db.ReadQueries.GetAlbum(db.Ctx, id)
+	if err != nil {
+		t.Fatalf("get album: %v", err)
+	}
+
+	if album.Mbid.String != "resolved-rg-mbid" {
+		t.Errorf("album mbid = %q, want the resolved one", album.Mbid.String)
+	}
+
+	if album.PendingReleaseMbid.Valid &&
+		album.PendingReleaseMbid.String != "" {
+		t.Errorf(
+			"the pending marker survived as %q",
+			album.PendingReleaseMbid.String,
+		)
+	}
+}
+
+// TestAResolvedMBIDIsNeverOverwritten covers the guard in the UPDATE.
+//
+// The pass runs against rows it read earlier, and a rescan can resolve
+// an album from its tags in between -- a real MBID from the file must
+// win over one this pass inferred from a release.
+func TestAResolvedMBIDIsNeverOverwritten(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+
+	id := seedPendingAlbum(t, db, "Pending Album", "release-mbid-1")
+
+	if err := db.Queries.SetAlbumMBID(db.Ctx, sqlcgen.SetAlbumMBIDParams{
+		Mbid: sql.NullString{String: "from-the-tags", Valid: true},
+		ID:   id,
+	}); err != nil {
+		t.Fatalf("set album mbid: %v", err)
+	}
+
+	if err := db.Queries.ResolveAlbumPendingReleaseMBID(
+		db.Ctx,
+		sqlcgen.ResolveAlbumPendingReleaseMBIDParams{
+			Mbid: sql.NullString{String: "from-the-backfill", Valid: true},
+			ID:   id,
+		},
+	); err != nil {
+		t.Fatalf("resolve pending release mbid: %v", err)
+	}
+
+	album, err := db.ReadQueries.GetAlbum(db.Ctx, id)
+	if err != nil {
+		t.Fatalf("get album: %v", err)
+	}
+
+	if album.Mbid.String != "from-the-tags" {
+		t.Errorf(
+			"album mbid = %q, want the tagged one to have won",
+			album.Mbid.String,
+		)
+	}
+}
+
+// TestThePassIsBounded checks the LIMIT.
+//
+// Each row costs a live MusicBrainz lookup on a 1 req/s limiter shared
+// with every page the user can open, so an unbounded read is a run that
+// lasts as long as the library is untagged. The sqlc query 013 wrote
+// had no LIMIT; the raw statement it was replacing did.
+func TestThePassIsBounded(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	e := newPendingTestService(db)
+
+	for i := range releaseGroupMBIDBackfillMaxPerRun + 10 {
+		seedPendingAlbum(
+			t, db,
+			"Album "+string(rune('A'+i%26))+strconv.Itoa(i),
+			"release-mbid-"+strconv.Itoa(i),
+		)
+	}
+
+	pending, err := e.pendingReleaseMBIDs(db.Ctx)
+	if err != nil {
+		t.Fatalf("the backfill's query failed: %v", err)
+	}
+
+	if len(pending) != releaseGroupMBIDBackfillMaxPerRun {
+		t.Errorf(
+			"got %d albums, want the run bounded at %d",
+			len(pending), releaseGroupMBIDBackfillMaxPerRun,
+		)
+	}
+}

backend/explore/prune_test.go

@@ -82,6 +82,100 @@ func TestPruneStaleLocalCrossReferences(t *testing.T) {
 	}
 }
 
+// TestPruneClearsInLibraryWithNoLocalID covers the fixed point: a row
+// carrying in_library with a NULL local_*_id.  The upsert's conflict
+// clause is `in_library = MAX(in_library, excluded.in_library)`, so it
+// can only ever raise the flag, and this pass used to be gated on the id
+// being present — which meant nothing in the app could clear such a row,
+// ever.  It is asserted for all three entity types because the gate was
+// written once and used three times, so a fix applied to one is a fix
+// that looks complete.
+//
+// The rows are seeded with raw SQL rather than through seedIndexResult
+// deliberately: upsertBatch writes a zero LocalArtistID as literal 0,
+// not NULL, and 0 satisfies `IS NOT NULL` — so the old gate already
+// caught that shape and a fixture built through the upsert cannot
+// reproduce this at all.  NULL is what the artifact importer and any
+// older writer leave behind, the column being nullable with no default.
+func TestPruneClearsInLibraryWithNoLocalID(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	si := NewSearchIndex(db, nil, nil, slog.Default())
+
+	// A genuinely owned artist, to prove the wider gate does not simply
+	// clear everything it now looks at.
+	database.InsertTestTrack(t, db, database.TestTrack{
+		FilePath: "/music/owned.mp3",
+		Artist:   "Owned",
+	})
+
+	artist, err := db.Queries.GetArtistByName(t.Context(), "Owned")
+	if err != nil {
+		t.Fatalf("read seeded artist: %v", err)
+	}
+
+	seedIndexResult(t, db, SearchIndexResult{
+		EntityType:    EntityArtist,
+		MBID:          testMBID("owned"),
+		Title:         "Owned",
+		ArtistName:    "Owned",
+		ArtistMBID:    testMBID("owned"),
+		InLibrary:     true,
+		LocalArtistID: artist.ID,
+	})
+
+	orphans := []struct {
+		name       string
+		entityType string
+		mbid       string
+	}{
+		{"artist", EntityArtist, "orphan-artist"},
+		{"release group", EntityReleaseGroup, "orphan-release-group"},
+		{"recording", EntityRecording, "orphan-recording"},
+	}
+
+	for _, o := range orphans {
+		if _, err := db.ExecContext(
+			`INSERT INTO explore_index
+			     (entity_type, mbid, title, artist_name, artist_mbid,
+			      in_library,
+			      local_artist_id, local_release_group_id, local_recording_id)
+			 VALUES (?, ?, ?, ?, ?, 1, ?, ?, ?)`,
+			dbEntityType(o.entityType), dbMBID(testMBID(o.mbid)), o.name, o.name,
+			dbMBID(testMBID(o.mbid)),
+			nil, nil, nil,
+		); err != nil {
+			t.Fatalf("seed %s orphan: %v", o.name, err)
+		}
+	}
+
+	si.pruneStaleLocalCrossReferences()
+
+	inLibrary := func(t *testing.T, mbid string) int {
+		t.Helper()
+
+		var flag int
+		if err := db.QueryRowWriter(
+			"SELECT in_library FROM explore_index WHERE mbid = ?", dbMBID(mbid),
+		).Scan(&flag); err != nil {
+			t.Fatalf("read in_library for %q: %v", mbid, err)
+		}
+
+		return flag
+	}
+
+	for _, o := range orphans {
+		if got := inLibrary(t, testMBID(o.mbid)); got != 0 {
+			t.Errorf("%s with a NULL local id: in_library = %d, want 0", o.name, got)
+		}
+	}
+
+	if got := inLibrary(t, testMBID("owned")); got != 1 {
+		t.Errorf("owned artist: in_library = %d, want 1 (it still has a file)", got)
+	}
+}
+
 // TestUnenrichedLibraryArtistMBIDs_OrdersByOwnedTrackCount verifies the
 // backfill queue prioritizes artists by how many tracks the user actually
 // owns, not by how many duplicate-mbid artist rows happen to exist (the

backend/explore/searchindex.go

@@ -2562,6 +2562,19 @@ func (si *SearchIndex) PopulateLocalCrossReferences() {
 // The row itself is left in place (it may still be part of the shipped
 // catalog, just no longer owned) — only the "this is mine" bookkeeping
 // is cleared.
+//
+// It is gated on the flag *or* the id, not on the id alone.  Gated on
+// the id, `in_library = 1 AND local_*_id IS NULL` is a fixed point: the
+// upsert can only ever raise the flag and this pass skipped such a row
+// by construction, so nothing in the app could clear it — a row claiming
+// to be owned, permanently, with no local row to check the claim
+// against.  Nothing in the tree writes that shape today
+// (collectLibraryEntities sets both together), which is exactly why it
+// is worth closing now: the exposure is a database written by an older
+// version, and the next writer that sets the flag without an id, which
+// nothing structurally prevents.  A NULL id fails the existence test on
+// its own, so the wider gate needs no second clause to say what "not
+// owned" means.
 func (si *SearchIndex) pruneStaleLocalCrossReferences() {
 	type prune struct {
 		entityType string
@@ -2594,7 +2607,8 @@ func (si *SearchIndex) pruneStaleLocalCrossReferences() {
 		result, err := si.db.ExecContext(
 			`UPDATE explore_index
 			 SET in_library = 0, `+p.column+` = NULL
-			 WHERE entity_type = ? AND `+p.column+` IS NOT NULL
+			 WHERE entity_type = ?
+			   AND (`+p.column+` IS NOT NULL OR in_library = 1)
 			   AND NOT EXISTS (`+p.exists+`)`,
 			dbEntityType(p.entityType),
 		)

backend/explore/types.go

@@ -41,7 +41,16 @@ type TopResult struct {
 	ReleaseGroupMBID string `json:"releaseGroupMbid,omitempty"`
 	ReleaseName      string `json:"releaseName,omitempty"`
 	// Library status — populated from index cross-reference columns.
+	//
+	// LocalID is the one the cards read.  It is the local row behind
+	// this entity — an album, a file, an artist — and it is set and
+	// cleared by a test against `audio_files`, so it means "there is
+	// something of mine here".  InLibrary is written by the same pass
+	// but is a one-way ratchet the prune can only clear alongside a
+	// local id, so it is the weaker of the two and stays for scoring
+	// (`fwInLibrary`), which is where an approximate answer is fine.
 	InLibrary bool  `json:"inLibrary"`
+	LocalID   int64 `json:"localId,omitempty"`
 }
 
 // MBArtist is a Wails-friendly projection of a MusicBrainz artist.

backend/library/completeness_test.go

@@ -232,3 +232,112 @@ func TestGetAlbumCompleteness_EmptyAlbum(t *testing.T) {
 		t.Errorf("empty album reported %+v, want zero and unknown", got)
 	}
 }
+
+// The batch and the single-album query are two spellings of one
+// question, and the thing worth pinning is that they never disagree.
+//
+// They are genuinely different SQL — the single-album form is
+// correlated subqueries over one album, the batch is two grouping
+// levels over a slice — so the risk is not a typo but a drift in
+// meaning: a disc's total counted once per file, a duplicate counted
+// twice, a disc with no total silently covered by one that had one.
+// Every shape the table above cares about is staged here at once,
+// because a batch that is only ever asked about one album is not being
+// asked the question that can go wrong.
+func TestGetAlbumsCompletenessAgreesWithTheSingleAlbumQuery(t *testing.T) {
+	t.Parallel()
+
+	lib, _ := setupTestLibrary(t)
+
+	shapes := map[int][]track{
+		1: disc(1, 100, 12, 12),
+		2: disc(1, 200, 9, 12),
+		3: disc(1, 300, 13, 12),
+		4: {{recordingID: 400, disc: 1, number: 1}},
+		5: append(disc(1, 500, 10, 10), disc(2, 600, 2, 5)...),
+		6: append(
+			disc(1, 700, 10, 10),
+			track{recordingID: 750, disc: 2, number: 1},
+		),
+		7: append(
+			disc(1, 800, 5, 6),
+			track{recordingID: 899, disc: 1, number: 3, total: 6},
+		),
+	}
+
+	ids := make([]int64, 0, len(shapes))
+
+	for albumID, tracks := range shapes {
+		stageAlbum(t, lib, albumID, tracks)
+		ids = append(ids, albumIDFor(t, lib, albumID))
+	}
+
+	batch, err := lib.GetAlbumsCompleteness(ids)
+	if err != nil {
+		t.Fatalf("GetAlbumsCompleteness: %v", err)
+	}
+
+	if len(batch) != len(ids) {
+		t.Fatalf("batch answered for %d albums, want %d", len(batch), len(ids))
+	}
+
+	for _, id := range ids {
+		one, err := lib.GetAlbumCompleteness(id)
+		if err != nil {
+			t.Fatalf("GetAlbumCompleteness(%d): %v", id, err)
+		}
+
+		if got := batch[id]; got != one {
+			t.Errorf("album %d: batch says %+v, single says %+v", id, got, one)
+		}
+	}
+}
+
+// An album with no files is absent from the batch, not zeroed.
+//
+// "I have none of this" and "I have no idea" are the third state Known
+// exists to keep apart, and a caller reading a missing key gets nothing
+// rather than a confident zero it would have to know to distrust.
+func TestGetAlbumsCompletenessOmitsAnAlbumWithNoFiles(t *testing.T) {
+	t.Parallel()
+
+	lib, _ := setupTestLibrary(t)
+
+	stageAlbum(t, lib, 1, disc(1, 100, 3, 3))
+
+	held := albumIDFor(t, lib, 1)
+
+	got, err := lib.GetAlbumsCompleteness([]int64{held, 4242})
+	if err != nil {
+		t.Fatalf("GetAlbumsCompleteness: %v", err)
+	}
+
+	if _, ok := got[4242]; ok {
+		t.Errorf("an album with no files answered %+v, want absent", got[4242])
+	}
+
+	if !got[held].Complete {
+		t.Errorf("held album reported %+v, want complete", got[held])
+	}
+}
+
+// A caller with nothing to ask about must not issue a query at all —
+// sqlc's empty-slice branch rewrites the placeholder to NULL, which is
+// a perfectly valid query returning nothing, so this is about the round
+// trip rather than the answer.
+func TestGetAlbumsCompletenessAsksNothingForAnEmptyList(t *testing.T) {
+	t.Parallel()
+
+	lib, _ := setupTestLibrary(t)
+
+	for _, ids := range [][]int64{nil, {}, {0}, {-1, 0}} {
+		got, err := lib.GetAlbumsCompleteness(ids)
+		if err != nil {
+			t.Fatalf("GetAlbumsCompleteness(%v): %v", ids, err)
+		}
+
+		if len(got) != 0 {
+			t.Errorf("GetAlbumsCompleteness(%v) = %+v, want empty", ids, got)
+		}
+	}
+}

backend/library/query.go

@@ -244,6 +244,65 @@ func (l *Library) GetAlbumCompleteness(albumID int64) (AlbumCompleteness, error)
 	}, nil
 }
 
+// GetAlbumsCompleteness answers the same question for a screenful of
+// albums in one query, keyed by album id.
+//
+// A card grid asks this about every card that has a local album behind
+// it, and one query per card is how a grid of fifty albums becomes
+// fifty round trips. The answer matters there for the reason it
+// matters on the album page: an album held 9 tracks of 12 has to show
+// the count, and a bare tick saying "in your library" is the complaint
+// this whole rule came from.
+//
+// An album with no row in the result is one with no files, and it is
+// absent rather than zeroed — "I have none of this" and "I have no
+// idea" are the same third state `Known` exists to keep apart, and a
+// caller reading a missing key gets nothing rather than a confident 0.
+func (l *Library) GetAlbumsCompleteness(
+	albumIDs []int64,
+) (map[int64]AlbumCompleteness, error) {
+	out := make(map[int64]AlbumCompleteness, len(albumIDs))
+
+	if len(albumIDs) == 0 {
+		return out, nil
+	}
+
+	keys := make([]sql.NullInt64, 0, len(albumIDs))
+
+	for _, id := range albumIDs {
+		if id <= 0 {
+			continue
+		}
+
+		keys = append(keys, sql.NullInt64{Int64: id, Valid: true})
+	}
+
+	if len(keys) == 0 {
+		return out, nil
+	}
+
+	rows, err := l.db.ReadQueries.GetAlbumsCompleteness(l.ctx, keys)
+	if err != nil {
+		l.logger.Error("could not get album completeness in batch",
+			"albums", len(keys), "error", err)
+
+		return nil, fmt.Errorf("could not get album completeness: %w", err)
+	}
+
+	for _, row := range rows {
+		known := row.Known != 0 && row.Expected > 0
+
+		out[row.AlbumID] = AlbumCompleteness{
+			Owned:    int(row.Owned),
+			Expected: int(row.Expected),
+			Known:    known,
+			Complete: known && row.Owned >= row.Expected,
+		}
+	}
+
+	return out, nil
+}
+
 // GetAlbumTracks returns one album's tracks in disc/track order.
 func (l *Library) GetAlbumTracks(albumID, libraryID int64) ([]Track, error) {
 	rows, err := l.db.ReadQueries.GetTracksByAlbum(

backend/mediacontrols/mpris_linux.go

@@ -279,17 +279,19 @@ func (h *MPRISHandler) enqueue(fn func()) {
 	}
 }
 
-// UpdateMetadata pushes track metadata to D-Bus.
-func (h *MPRISHandler) UpdateMetadata(meta Metadata) {
-	h.mu.Lock()
-	h.trackID++
-	tid := h.trackID
-	h.mu.Unlock()
-
-	m := map[string]interface{}{
+// metadataMap builds the org.mpris.MediaPlayer2.Player Metadata value
+// for one track.
+//
+// It is separated from UpdateMetadata, which needs a live D-Bus
+// connection, so the map's contents can be asserted on: this file is
+// behind a build tag and everything in it that touches h is reachable
+// only from a session bus, which is the same reason the Android
+// contract lives in an untagged androidpayload.go.
+func metadataMap(meta Metadata, trackID uint64) map[string]any {
+	m := map[string]any{
 		"mpris:trackid": dbus.ObjectPath(
 			fmt.Sprintf(
-				"/org/yellowjacket/Track/%d", tid,
+				"/org/yellowjacket/Track/%d", trackID,
 			),
 		),
 	}
@@ -306,16 +308,45 @@ func (h *MPRISHandler) UpdateMetadata(meta Metadata) {
 		m["xesam:album"] = meta.Album
 	}
 
+	// Always present, even with nothing to point at.
+	//
+	// Every other key here can be omitted safely because a client
+	// reading the map sees a track with no title or no album and
+	// renders it that way. Art is different: KDE's applet (and
+	// others) treat an *absent* mpris:artUrl as "no news about the
+	// art" and keep drawing whatever the last track had, so playing
+	// something with no cover left the previous album's sleeve on
+	// screen — which reads as the wrong track playing rather than as
+	// missing artwork.
+	//
+	// An empty string is the honest answer and is what the spec's
+	// "URI" type degrades to; a client that cannot load it falls back
+	// to its own placeholder, which is the behaviour wanted.
+	artURL := ""
 	if meta.ArtFilePath != "" {
-		m["mpris:artUrl"] = "file://" + meta.ArtFilePath
+		artURL = "file://" + meta.ArtFilePath
 	}
 
+	m["mpris:artUrl"] = artURL
+
 	if meta.DurationSec > 0 {
 		m["mpris:length"] = int64(
 			meta.DurationSec,
 		) * usPerSec
 	}
 
+	return m
+}
+
+// UpdateMetadata pushes track metadata to D-Bus.
+func (h *MPRISHandler) UpdateMetadata(meta Metadata) {
+	h.mu.Lock()
+	h.trackID++
+	tid := h.trackID
+	h.mu.Unlock()
+
+	m := metadataMap(meta, tid)
+
 	h.enqueue(func() {
 		h.props.SetMust(playerIf, "Metadata", m)
 	})

backend/mediacontrols/mpris_linux_test.go

@@ -0,0 +1,86 @@
+//go:build linux && !android
+
+package mediacontrols
+
+import "testing"
+
+// The one key that must be present even when it is empty.
+//
+// Everything else in the map may be omitted, because a client reading
+// it renders a track with no title as a track with no title. Art is
+// different: KDE's applet treats an *absent* mpris:artUrl as no news
+// about the art and keeps drawing the last one it saw, so a track with
+// no cover wore the previous album's sleeve — which reads as the wrong
+// track playing rather than as missing artwork.
+func TestMetadataMapAlwaysCarriesArtURL(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		meta Metadata
+		want string
+	}{
+		{
+			name: "no art at all",
+			meta: Metadata{Title: "Blue in Green"},
+			want: "",
+		},
+		{
+			name: "art on disk",
+			meta: Metadata{
+				Title:       "Blue in Green",
+				ArtFilePath: "/covers/kind-of-blue_lg.jpg",
+			},
+			want: "file:///covers/kind-of-blue_lg.jpg",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			m := metadataMap(tt.meta, 1)
+
+			got, ok := m["mpris:artUrl"]
+			if !ok {
+				t.Fatal("mpris:artUrl is absent; it must always be sent")
+			}
+
+			if got != tt.want {
+				t.Errorf("mpris:artUrl = %v, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+// The trackid has to change between tracks or a client is entitled to
+// treat the metadata as describing the same track it already has.
+func TestMetadataMapTrackIDVaries(t *testing.T) {
+	t.Parallel()
+
+	first := metadataMap(Metadata{Title: "A"}, 1)["mpris:trackid"]
+	second := metadataMap(Metadata{Title: "B"}, 2)["mpris:trackid"]
+
+	if first == second {
+		t.Errorf("trackid did not change: %v", first)
+	}
+}
+
+// The optional keys stay optional — this is what makes artUrl's
+// always-present treatment a deliberate exception rather than drift.
+func TestMetadataMapOmitsEmptyOptionalFields(t *testing.T) {
+	t.Parallel()
+
+	m := metadataMap(Metadata{}, 1)
+
+	for _, key := range []string{
+		"xesam:title",
+		"xesam:artist",
+		"xesam:album",
+		"mpris:length",
+	} {
+		if _, ok := m[key]; ok {
+			t.Errorf("%s is present for an empty Metadata", key)
+		}
+	}
+}

backend/player/buffered_stall_test.go

@@ -0,0 +1,188 @@
+package player
+
+import (
+	"errors"
+	"testing"
+	"time"
+
+	"github.com/gopxl/beep/v2"
+)
+
+// errTestDecode stands in for a decoder blowing up mid-track.
+var errTestDecode = errors.New("decode blew up")
+
+// stalledStreamer never produces a sample and never reports
+// end-of-stream: (0, true), forever. A damaged file that decodes to
+// nothing looks like this, and so does any source whose producer has
+// quietly stopped.
+type stalledStreamer struct{}
+
+func (stalledStreamer) Stream(_ [][2]float64) (int, bool) { return 0, true }
+func (stalledStreamer) Err() error                        { return nil }
+
+// failingStreamer produces n good samples and then fails, which is
+// what a decode error mid-track looks like: the same (0, false) a
+// finished track returns, distinguishable only by Err.
+type failingStreamer struct {
+	remaining int
+	err       error
+}
+
+func (f *failingStreamer) Stream(samples [][2]float64) (int, bool) {
+	if f.remaining <= 0 {
+		return 0, false
+	}
+
+	n := min(len(samples), f.remaining)
+
+	for i := range n {
+		samples[i] = [2]float64{1, 1}
+	}
+
+	f.remaining -= n
+
+	return n, true
+}
+
+func (f *failingStreamer) Err() error { return f.err }
+
+// drainUntilEnd calls Stream until it reports end-of-stream, or gives
+// up. It returns whether the stream ended.
+//
+// The give-up bound is wall clock rather than a call count: the stall
+// budget is a duration, so a tight loop has to actually wait it out.
+func drainUntilEnd(bs *BufferedStreamer, within time.Duration) bool {
+	buf := make([][2]float64, 512)
+	deadline := time.Now().Add(within)
+
+	for time.Now().Before(deadline) {
+		if _, ok := bs.Stream(buf); !ok {
+			return true
+		}
+
+		time.Sleep(time.Millisecond)
+	}
+
+	return false
+}
+
+// A source that stops producing without ever ending is the fault this
+// whole file exists for: Stream used to answer with silence and ok
+// forever, so the chain never ended, the player stayed in Playing
+// with the button showing pause, and the decoder's position never
+// moved -- a frozen seek bar over a track that was not playing.
+func TestAStalledSourceEndsTheStream(t *testing.T) {
+	bs := NewBufferedStreamer(stalledStreamer{}, 2048)
+	defer bs.Close()
+
+	if !drainUntilEnd(bs, maxStarvedDuration+2*time.Second) {
+		t.Fatal(
+			"a stalled source never ended the stream: the player " +
+				"would sit in Playing with a frozen position",
+		)
+	}
+
+	if !errors.Is(bs.Err(), errSourceStalled) {
+		t.Fatalf(
+			"expected the stall to be reported, got %v", bs.Err(),
+		)
+	}
+}
+
+// Close is the other exit that used to leave `done` false, with the
+// same consequence: the ring drains and every call after it is
+// silence that claims to be audio.
+func TestClosingEndsTheStream(t *testing.T) {
+	bs := NewBufferedStreamer(finiteStreamer(1<<20), 2048)
+
+	// Let the read-ahead fill something, so this exercises the drain
+	// after Close rather than a buffer that was empty anyway.
+	time.Sleep(20 * time.Millisecond)
+	bs.Close()
+
+	if !drainUntilEnd(bs, 2*time.Second) {
+		t.Fatal("a closed streamer never reported end-of-stream")
+	}
+}
+
+// A source that fails is not a source that finished, and only Err
+// tells them apart. Before this, the player reported a mid-track
+// decode failure to the queue as a natural end, so the queue
+// auto-advanced in silence and counted the broken track as played.
+func TestAFailedSourceReportsItsError(t *testing.T) {
+	src := &failingStreamer{remaining: 4096, err: errTestDecode}
+
+	bs := NewBufferedStreamer(src, 2048)
+	defer bs.Close()
+
+	if !drainUntilEnd(bs, 2*time.Second) {
+		t.Fatal("a failing source never reported end-of-stream")
+	}
+
+	if !errors.Is(bs.Err(), errTestDecode) {
+		t.Fatalf(
+			"expected the source's error to survive, got %v",
+			bs.Err(),
+		)
+	}
+}
+
+// The ordinary case has to keep working: a source that ends cleanly
+// ends with no error, or every finished track would be reported as a
+// failure and skipped.
+func TestADrainedSourceReportsNoError(t *testing.T) {
+	bs := NewBufferedStreamer(finiteStreamer(4096), 2048)
+	defer bs.Close()
+
+	if !drainUntilEnd(bs, 2*time.Second) {
+		t.Fatal("a finite source never reported end-of-stream")
+	}
+
+	if bs.Err() != nil {
+		t.Fatalf(
+			"a track that finished normally reported %v", bs.Err(),
+		)
+	}
+}
+
+// A slow source is exactly what the read-ahead exists to absorb, so
+// underruns must not be charged cumulatively -- otherwise a file on a
+// slow disk ends itself partway through.
+func TestUnderrunsDoNotAccumulateAcrossASlowSource(t *testing.T) {
+	const total = 8192
+
+	src := &slowStreamer{
+		inner: finiteStreamer(total),
+		delay: 2 * time.Millisecond,
+	}
+
+	bs := NewBufferedStreamer(src, 1024)
+	defer bs.Close()
+
+	buf := make([][2]float64, 256)
+	got := 0
+
+	for {
+		n, ok := bs.Stream(buf)
+		if !ok {
+			break
+		}
+
+		for i := range n {
+			if buf[i][0] != 0 {
+				got++
+			}
+		}
+	}
+
+	if got != total {
+		t.Fatalf(
+			"a slow but healthy source was cut short: got %d of %d "+
+				"samples",
+			got, total,
+		)
+	}
+}
+
+// beep.Streamer is what the player wraps; keep the type honest.
+var _ beep.Streamer = (*BufferedStreamer)(nil)

backend/player/buffered_streamer.go

@@ -1,6 +1,7 @@
 package player
 
 import (
+	"errors"
 	"sync"
 	"time"
 
@@ -34,8 +35,78 @@ type BufferedStreamer struct {
 	done    bool
 	err     error
 	closed  chan struct{}
+
+	// starved counts consecutive Stream calls served with silence
+	// because the ring was empty, and starvedSince is when that run
+	// began.  An underrun is legitimate for a moment -- that is what
+	// the read-ahead exists to absorb -- but it is not legitimate
+	// forever, and "forever" is indistinguishable from healthy
+	// playback everywhere above this type: the chain never ends, so
+	// the player stays in Playing with the button showing pause, and
+	// the decoder's position never moves, so the 1 Hz report pins the
+	// seek bar and suppresses its interpolation.
+	starved      int
+	starvedSince time.Time
+
+	// underruns accumulates for the life of this streamer, where
+	// starved is reset by every arriving sample.
+	//
+	// The two answer different questions and only the first was being
+	// asked. starved is a *stall* detector: it exists to end a track
+	// whose source has died, so it forgets a run the moment audio
+	// resumes -- which is exactly the case this counts. A hundred 20ms
+	// underruns a minute never approach the give-up threshold and were
+	// invisible to the log, the UI and every test tier, while being
+	// audible as static: an underrun is served as a run of zeros
+	// spliced into the waveform, and a step discontinuity at each edge
+	// is what a click is.
+	underruns UnderrunStats
 }
 
+// UnderrunStats is what the ring buffer missed, cumulatively.
+//
+// Samples rather than milliseconds because this type does not know the
+// sample rate -- the player does, and converts at the point of
+// reporting.
+type UnderrunStats struct {
+	// Runs is the number of *episodes*: transitions from healthy into
+	// starved. Calls is how many Stream calls were served with
+	// silence, and Samples is how much silence that was.
+	//
+	// Runs is the count that means something audible. One episode is
+	// one pop however many calls it spans, and the ratio of the two is
+	// how long the average episode was -- which is what separates
+	// "clicking" from "dropping out".
+	Runs    int64
+	Calls   int64
+	Samples int64
+}
+
+// The silence fill is bounded by both a duration and a run of calls,
+// and it needs both.
+//
+// Duration alone is the real measure -- the speaker paces itself, so
+// wall clock is what says whether the source has actually stopped --
+// but a caller draining in a tight loop (a test, a decode-to-buffer)
+// makes hundreds of calls in microseconds and would trip nothing.
+// A call count alone is the opposite failure: the same tight loop
+// spends the whole budget before the read-ahead goroutine has been
+// scheduled once, and ends a perfectly good stream at sample zero.
+//
+// The duration is longer than the 2 s read-ahead it is there to
+// outlast, and the count is short enough that the speaker (~200 ms a
+// call) reaches it well inside that.
+const (
+	maxStarvedDuration = 3 * time.Second
+	minStarvedCalls    = 8
+)
+
+// errSourceStalled is returned by Err when the source stopped
+// producing samples without ever reporting end-of-stream.
+var errSourceStalled = errors.New(
+	"audio source stopped producing samples",
+)
+
 // NewBufferedStreamer creates a BufferedStreamer that pre-fills
 // bufferSize samples from source via a background goroutine.
 // A typical bufferSize is 2× the sample rate (~2 seconds of audio).
@@ -54,8 +125,24 @@ func NewBufferedStreamer(
 	return bs
 }
 
+// finish marks the stream ended, recording err as the reason when
+// there is one.  Every exit from readAhead goes through it: an exit
+// that leaves done false strands Stream in its underrun branch,
+// where it returns silence and ok forever.
+func (bs *BufferedStreamer) finish(err error) {
+	bs.mu.Lock()
+	defer bs.mu.Unlock()
+
+	bs.done = true
+
+	if err != nil && bs.err == nil {
+		bs.err = err
+	}
+}
+
 // readAhead continuously reads from the source into the ring buffer
 // until the source is drained, an error occurs, or Close is called.
+// It always marks the stream done on the way out.
 func (bs *BufferedStreamer) readAhead() {
 	// Temporary buffer for reading from source outside the lock.
 	// 512 samples per chunk keeps the critical section short.
@@ -63,6 +150,13 @@ func (bs *BufferedStreamer) readAhead() {
 
 	tmp := make([][2]float64, chunkSize)
 
+	// Every exit marks the stream done.  An exit that does not is what
+	// stranded Stream in its underrun branch, returning silence and ok
+	// for the rest of the process's life.
+	var exitErr error
+
+	defer func() { bs.finish(exitErr) }()
+
 	for {
 		// Check if closed.
 		select {
@@ -72,6 +166,15 @@ func (bs *BufferedStreamer) readAhead() {
 		}
 
 		bs.mu.Lock()
+
+		// Stream gave up waiting for us.  Nothing downstream is
+		// listening any more, so filling the ring is work for nobody.
+		if bs.done {
+			bs.mu.Unlock()
+
+			return
+		}
+
 		space := len(bs.ring) - bs.count
 
 		if space == 0 {
@@ -115,14 +218,12 @@ func (bs *BufferedStreamer) readAhead() {
 		}
 
 		if !ok {
-			bs.mu.Lock()
-			bs.done = true
-
-			if srcErr := bs.source.Err(); srcErr != nil {
-				bs.err = srcErr
-			}
-
-			bs.mu.Unlock()
+			// A drained source and a failed one both land here and are
+			// not the same event: one is a track that ended, the other
+			// is a track that broke.  Err is what tells them apart, and
+			// it is why the player must ask before treating this as a
+			// natural finish.
+			exitErr = bs.source.Err()
 
 			return
 		}
@@ -154,7 +255,34 @@ func (bs *BufferedStreamer) Stream(
 	}
 
 	if bs.count == 0 {
-		// Buffer temporarily empty — fill with silence.
+		// The read-ahead has not caught up.  Silence buys it time --
+		// but only for a bounded stretch, because "forever" is
+		// reported upward as healthy playback and there is no watchdog
+		// above this to notice otherwise.
+		if bs.starved == 0 {
+			bs.underruns.Runs++
+		}
+
+		bs.underruns.Calls++
+		bs.underruns.Samples += int64(len(samples))
+
+		bs.starved++
+
+		if bs.starvedSince.IsZero() {
+			bs.starvedSince = time.Now()
+		}
+
+		if bs.starved >= minStarvedCalls &&
+			time.Since(bs.starvedSince) > maxStarvedDuration {
+			bs.done = true
+
+			if bs.err == nil {
+				bs.err = errSourceStalled
+			}
+
+			return 0, false
+		}
+
 		for i := range samples {
 			samples[i] = [2]float64{}
 		}
@@ -162,6 +290,9 @@ func (bs *BufferedStreamer) Stream(
 		return len(samples), true
 	}
 
+	// Samples arrived, so whatever the stall was, it is over.
+	bs.resetStarvationLocked()
+
 	// Copy available samples from ring buffer.
 	n := len(samples)
 	if n > bs.count {
@@ -178,6 +309,20 @@ func (bs *BufferedStreamer) Stream(
 	return n, true
 }
 
+// Underruns returns the cumulative underrun count.
+//
+// It is a snapshot rather than a live view, and it is read from
+// outside the audio callback: counting happens in Stream, under the
+// lock it already takes, because that path has a real-time deadline
+// and anything that allocates or formats on it is a cause of the
+// defect it is measuring rather than a measurement of it.
+func (bs *BufferedStreamer) Underruns() UnderrunStats {
+	bs.mu.Lock()
+	defer bs.mu.Unlock()
+
+	return bs.underruns
+}
+
 // Err returns any error encountered by the source streamer.
 func (bs *BufferedStreamer) Err() error {
 	bs.mu.Lock()
@@ -197,6 +342,23 @@ func (bs *BufferedStreamer) Flush() {
 	bs.readPos = 0
 	bs.writPos = 0
 	bs.count = 0
+
+	// A seek empties the ring on purpose, and the refill that follows
+	// is exactly the stall the budget exists to tolerate.  Charging it
+	// against a budget the previous underrun already spent would end
+	// the track on a seek near the end of a slow file.
+	bs.resetStarvationLocked()
+}
+
+// resetStarvationLocked forgets an underrun run.  Must be called with
+// bs.mu held.
+//
+// Deliberately does not touch bs.underruns: forgetting the run is what
+// makes starved a stall detector, and remembering it is the whole
+// point of the counter beside it.
+func (bs *BufferedStreamer) resetStarvationLocked() {
+	bs.starved = 0
+	bs.starvedSince = time.Time{}
 }
 
 // LockSource blocks the read-ahead goroutine from touching the

backend/player/buffered_underrun_test.go

@@ -0,0 +1,279 @@
+package player
+
+import (
+	"sync"
+	"testing"
+	"time"
+)
+
+// An underrun is audible and nothing counted it (#135).
+//
+// The distinction these tests exist for is that `starved` and
+// `underruns` disagree on purpose. `starved` is a stall detector: it is
+// reset by every arriving sample, because its job is to end a track
+// whose source has died and a source that is merely slow must not be
+// cut short (TestUnderrunsDoNotAccumulateAcrossASlowSource, next
+// door). That reset is exactly what made the audible case invisible --
+// a hundred short underruns a minute never approach the give-up
+// threshold, and each one is a run of zeros spliced into the waveform
+// with a step discontinuity at both edges.
+
+// TestAnEmptyRingIsCounted is the measurement itself: silence served
+// for a missing sample is recorded rather than merely tolerated.
+func TestAnEmptyRingIsCounted(t *testing.T) {
+	t.Parallel()
+
+	// A source that never produces is the cleanest way to make the
+	// ring empty on demand; the stall budget is far longer than the
+	// handful of calls below.
+	bs := NewBufferedStreamer(stalledStreamer{}, 1024)
+	defer bs.Close()
+
+	if got := bs.Underruns(); got != (UnderrunStats{}) {
+		t.Fatalf("a fresh streamer already reports %+v", got)
+	}
+
+	buf := make([][2]float64, 256)
+
+	for range 3 {
+		if _, ok := bs.Stream(buf); !ok {
+			t.Fatal("the stall budget ran out before the test did")
+		}
+	}
+
+	got := bs.Underruns()
+
+	if got.Calls != 3 {
+		t.Errorf("Calls = %d, want 3", got.Calls)
+	}
+
+	if got.Samples != int64(3*len(buf)) {
+		t.Errorf("Samples = %d, want %d", got.Samples, 3*len(buf))
+	}
+
+	// Three consecutive silent calls are one episode, not three. That
+	// is the number that means something audible: one interruption is
+	// one pop however many callbacks it spans.
+	if got.Runs != 1 {
+		t.Errorf("Runs = %d, want 1 -- an unbroken run is one episode", got.Runs)
+	}
+}
+
+// TestSilenceIsWhatIsCounted pins what an underrun actually does to the
+// waveform, which is the reason to count it at all.
+func TestSilenceIsWhatIsCounted(t *testing.T) {
+	t.Parallel()
+
+	bs := NewBufferedStreamer(stalledStreamer{}, 1024)
+	defer bs.Close()
+
+	buf := make([][2]float64, 64)
+	for i := range buf {
+		buf[i] = [2]float64{0.5, 0.5}
+	}
+
+	n, ok := bs.Stream(buf)
+	if !ok || n != len(buf) {
+		t.Fatalf("Stream = (%d, %v), want (%d, true)", n, ok, len(buf))
+	}
+
+	for i := range buf {
+		if buf[i] != ([2]float64{}) {
+			t.Fatalf("sample %d is %v, want silence", i, buf[i])
+		}
+	}
+
+	if got := bs.Underruns().Samples; got != int64(len(buf)) {
+		t.Errorf("counted %d samples of silence, wrote %d", got, len(buf))
+	}
+}
+
+// TestSeparateEpisodesAreSeparateRuns is the counter's whole shape:
+// audio arriving between two underruns makes them two, because that is
+// two interruptions and two clicks.
+func TestSeparateEpisodesAreSeparateRuns(t *testing.T) {
+	t.Parallel()
+
+	// A source that yields nothing until it is fed, so the ring can be
+	// emptied, filled and emptied again on demand.
+	src := &gatedStreamer{}
+
+	bs := NewBufferedStreamer(src, 1024)
+	defer bs.Close()
+
+	buf := make([][2]float64, 128)
+
+	starve := func() {
+		t.Helper()
+
+		for range 2 {
+			if _, ok := bs.Stream(buf); !ok {
+				t.Fatal("the stall budget ran out before the test did")
+			}
+		}
+	}
+
+	// feed lets exactly one bufferful through and drains it, so the
+	// ring is empty again on return. Allowing more would mean the
+	// starve() after it drained real audio instead of underrunning,
+	// which is what the first version of this test did -- it reported
+	// one episode and looked like the counter was wrong.
+	feed := func() {
+		t.Helper()
+
+		src.allow(len(buf))
+
+		// The read-ahead is a goroutine, so wait for real samples
+		// rather than assuming they have landed.
+		deadline := time.Now().Add(2 * time.Second)
+		for time.Now().Before(deadline) {
+			n, ok := bs.Stream(buf)
+			if ok && n > 0 && buf[0] != ([2]float64{}) {
+				return
+			}
+
+			time.Sleep(time.Millisecond)
+		}
+
+		t.Fatal("the source never delivered a sample")
+	}
+
+	starve()
+	feed()
+	starve()
+
+	if got := bs.Underruns().Runs; got < 2 {
+		t.Errorf(
+			"Runs = %d, want at least 2 -- audio in between makes two "+
+				"episodes, not one",
+			got,
+		)
+	}
+}
+
+// TestTheStallResetDoesNotClearTheCounter is the regression this file
+// is really about.
+//
+// resetStarvationLocked runs on every arriving sample and on every
+// Flush. If it cleared the cumulative count too, the counter would
+// report zero on exactly the workload it exists to measure -- a stream
+// that underruns repeatedly but always recovers -- which is
+// indistinguishable from healthy playback and is what the code did
+// before #135.
+func TestTheStallResetDoesNotClearTheCounter(t *testing.T) {
+	t.Parallel()
+
+	bs := NewBufferedStreamer(stalledStreamer{}, 1024)
+	defer bs.Close()
+
+	buf := make([][2]float64, 128)
+
+	if _, ok := bs.Stream(buf); !ok {
+		t.Fatal("the stall budget ran out before the test did")
+	}
+
+	before := bs.Underruns()
+	if before.Runs == 0 {
+		t.Fatal("nothing was counted, so the reset cannot be tested")
+	}
+
+	// Both of the ways a run is forgotten.
+	bs.mu.Lock()
+	bs.resetStarvationLocked()
+	bs.mu.Unlock()
+
+	bs.Flush()
+
+	if got := bs.Underruns(); got != before {
+		t.Errorf(
+			"forgetting the stall run also discarded the count: %+v, "+
+				"want %+v",
+			got, before,
+		)
+	}
+}
+
+// TestUnderrunDeltaNeverGoesBackwards covers the one arithmetic trap in
+// the reporting side.
+//
+// The counter belongs to the streamer and the streamer is replaced on
+// every track, so a baseline carried across a track change is the
+// previous track's total subtracted from a fresh zero. The load path
+// resets the baseline, and this clamps as well -- a negative count in a
+// log line reads as a broken instrument, which would discredit the
+// measurement rather than merely mis-state it.
+func TestUnderrunDeltaNeverGoesBackwards(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		now  UnderrunStats
+		last UnderrunStats
+		want UnderrunStats
+	}{
+		{
+			name: "ordinary progress",
+			now:  UnderrunStats{Runs: 5, Calls: 40, Samples: 4000},
+			last: UnderrunStats{Runs: 2, Calls: 10, Samples: 1000},
+			want: UnderrunStats{Runs: 3, Calls: 30, Samples: 3000},
+		},
+		{
+			name: "nothing happened",
+			now:  UnderrunStats{Runs: 5, Calls: 40, Samples: 4000},
+			last: UnderrunStats{Runs: 5, Calls: 40, Samples: 4000},
+			want: UnderrunStats{},
+		},
+		{
+			name: "a new streamer, with a stale baseline",
+			now:  UnderrunStats{},
+			last: UnderrunStats{Runs: 9, Calls: 90, Samples: 9000},
+			want: UnderrunStats{},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			if got := underrunDelta(tt.now, tt.last); got != tt.want {
+				t.Errorf("underrunDelta = %+v, want %+v", got, tt.want)
+			}
+		})
+	}
+}
+
+// gatedStreamer produces only what it has been allowed to, and
+// otherwise stalls without ending -- so a test can decide exactly when
+// the ring runs dry.
+type gatedStreamer struct {
+	mu        sync.Mutex
+	remaining int
+}
+
+func (g *gatedStreamer) allow(n int) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+
+	g.remaining += n
+}
+
+func (g *gatedStreamer) Stream(samples [][2]float64) (int, bool) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+
+	if g.remaining <= 0 {
+		return 0, true
+	}
+
+	n := min(len(samples), g.remaining)
+
+	for i := range n {
+		samples[i] = [2]float64{0.25, 0.25}
+	}
+
+	g.remaining -= n
+
+	return n, true
+}
+
+func (g *gatedStreamer) Err() error { return nil }

backend/player/loadstate_test.go

@@ -0,0 +1,213 @@
+package player
+
+import (
+	"log/slog"
+	"testing"
+	"time"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+
+	"yellowjacket/backend/events"
+	"yellowjacket/internal/testfixtures"
+)
+
+// fixtureSampleRate is what cmd/gentestdata writes (audio.go).  It is
+// deliberately not the speaker rate, which is what lets these tests
+// tell the decoder's format from the player's default.
+const fixtureSampleRate = 22050
+
+// newTestPlayer is a player with a context and no database, so the
+// track-metadata lookup cannot succeed.
+func newTestPlayer(t *testing.T) *Player {
+	t.Helper()
+
+	p := NewPlayer(slog.Default(), nil)
+	rec := events.NewRecorder()
+
+	_ = p.ServiceStartup(
+		events.WithSink(t.Context(), rec),
+		application.ServiceOptions{},
+	)
+
+	return p
+}
+
+// loadFileLocked needs no speaker: it decodes, builds the chain and
+// registers it paused. speaker.Play on an uninitialised device is
+// what the integration guard elsewhere is about, so these assert on
+// the state the load computed rather than on playback.
+
+// p.format used to be assigned once, in the constructor, to the
+// *speaker's* rate -- so it claimed 44.1 kHz for every file ever
+// loaded. Play()'s replay-after-finish path resamples from it, so a
+// finished track played again was resampled from a rate the decoder
+// never produced: audibly the wrong speed and pitch, and wrong
+// length and position arithmetic with it.
+//
+// The fixtures are 22050 Hz, which is exactly the point -- any of
+// them disagrees with the speaker rate.
+func TestLoadRecordsTheDecodersOwnFormat(t *testing.T) {
+	m := testfixtures.Load(t)
+	path := m.Case(t, testfixtures.CaseCoverDedup)[0]
+
+	p := newTestPlayer(t)
+
+	if got := p.format.SampleRate; got != speakerSampleRate {
+		t.Fatalf(
+			"precondition: a fresh player should hold the speaker "+
+				"rate, got %d",
+			got,
+		)
+	}
+
+	if err := p.LoadFile(path); err != nil {
+		t.Fatalf("LoadFile(%s): %v", path, err)
+	}
+
+	if p.format.SampleRate == speakerSampleRate {
+		t.Fatalf(
+			"p.format still holds the speaker rate (%d) after "+
+				"loading a %d Hz file: the replay path would "+
+				"resample from the wrong rate",
+			speakerSampleRate, fixtureSampleRate,
+		)
+	}
+
+	if got := int(p.format.SampleRate); got != fixtureSampleRate {
+		t.Errorf(
+			"expected the decoder's rate %d, got %d",
+			fixtureSampleRate, got,
+		)
+	}
+}
+
+// trackLengthMs is written only when the database has a row for the
+// file and cleared only by UnloadTrack, so a track with no row used
+// to inherit whatever the last track's duration was -- and every
+// position report is scaled by it, so the whole seek bar was then
+// reporting one track's progress on another track's scale.
+//
+// There is no database here, so the lookup cannot succeed: exactly
+// the case that used to inherit.
+func TestLoadDoesNotInheritThePreviousTracksDuration(t *testing.T) {
+	m := testfixtures.Load(t)
+	path := m.Case(t, testfixtures.CaseCoverDedup)[0]
+
+	p := newTestPlayer(t)
+
+	// Stand in for a previous track whose duration was resolved.
+	p.trackLengthMs = 9_999_000
+
+	if err := p.LoadFile(path); err != nil {
+		t.Fatalf("LoadFile(%s): %v", path, err)
+	}
+
+	if p.trackLengthMs == 9_999_000 {
+		t.Fatal(
+			"the previous track's duration survived the load: every " +
+				"position report for this track would be scaled by it",
+		)
+	}
+}
+
+// A new chain supersedes the old one's pending finished callback.
+// Without this, a callback that queued for p.mu behind a LoadFile
+// woke up and rewound, stopped and auto-advanced the *new* track.
+func TestANewChainSupersedesTheOldFinishedCallback(t *testing.T) {
+	m := testfixtures.Load(t)
+	paths := m.Case(t, testfixtures.CaseCoverDedup)
+
+	if len(paths) < 2 {
+		t.Skip("need two fixture tracks")
+	}
+
+	p := newTestPlayer(t)
+
+	if err := p.LoadFile(paths[0]); err != nil {
+		t.Fatalf("LoadFile(%s): %v", paths[0], err)
+	}
+
+	stale := p.chainID
+
+	if err := p.LoadFile(paths[1]); err != nil {
+		t.Fatalf("LoadFile(%s): %v", paths[1], err)
+	}
+
+	if p.chainID == stale {
+		t.Fatal("loading a second file did not supersede the chain")
+	}
+
+	called := false
+
+	p.SetPlaybackFinishedHandler(func(error) { called = true })
+
+	// The first track's callback, arriving late.
+	p.onPlaybackFinished(stale, nil)
+
+	if called {
+		t.Error(
+			"a superseded chain's callback drove auto-advance: the " +
+				"track that is loaded now would be skipped",
+		)
+	}
+
+	if p.state == Stopped {
+		t.Error(
+			"a superseded chain's callback stopped the current track",
+		)
+	}
+}
+
+// The decoder is read by the read-ahead goroutine and by every
+// position emit, and those used to be guarded by different mutexes:
+// the read by srcMu, the position by the speaker lock, which
+// read-ahead never takes. Under -race this failed on the emit that
+// LoadFile itself makes.
+//
+// It needs the read-ahead goroutine to actually be running, so it
+// keeps asking for the position for long enough to overlap it.
+func TestPositionReadsDoNotRaceTheReadAhead(t *testing.T) {
+	m := testfixtures.Load(t)
+	path := m.Case(t, testfixtures.CaseFLACAlbum)[0]
+
+	p := newTestPlayer(t)
+
+	if err := p.LoadFile(path); err != nil {
+		t.Fatalf("LoadFile(%s): %v", path, err)
+	}
+
+	for range 200 {
+		if _, err := p.CurrentPositionSeconds(); err != nil {
+			t.Fatalf("CurrentPositionSeconds: %v", err)
+		}
+	}
+}
+
+// Seeking emits the landing position, and that emit reads the
+// decoder -- so the source lock the seek holds must be released
+// before it. A reentrant take here is a deadlock, not a failure,
+// which is why this test exists rather than a comment.
+func TestSeekEmitsWithoutDeadlocking(t *testing.T) {
+	m := testfixtures.Load(t)
+	path := m.Case(t, testfixtures.CaseFLACAlbum)[0]
+
+	p := newTestPlayer(t)
+
+	if err := p.LoadFile(path); err != nil {
+		t.Fatalf("LoadFile(%s): %v", path, err)
+	}
+
+	done := make(chan struct{})
+
+	go func() {
+		defer close(done)
+
+		_ = p.Seek(1)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(10 * time.Second):
+		t.Fatal("Seek deadlocked: the position emit re-took the source lock")
+	}
+}

backend/player/player.go

@@ -49,11 +49,24 @@ type Player struct {
 	seeker       beep.StreamSeeker
 	resampled    beep.Streamer
 	buffered     *BufferedStreamer
+
+	// lastUnderruns is the previous report, so the 1 Hz log can say
+	// what happened in the last second and stay quiet when nothing did.
+	// It is reset with the streamer, in loadFileLocked.
+	lastUnderruns           UnderrunStats
 	control                 *beep.Ctrl
 	volume                  *effects.Volume
 	speakerStreamer         beep.Streamer
-	playbackFinishedHandler func()
+	playbackFinishedHandler func(error)
 	trackChangeID           uint64
+
+	// chainID identifies the streamer chain currently registered with
+	// the speaker.  updateStreamers bumps it, and the finished
+	// callback carries the value it was registered with, so a callback
+	// that queued for p.mu behind a LoadFile can tell that the player
+	// has moved on and return rather than rewinding somebody else's
+	// track.
+	chainID       uint64
 	mediaControls mediacontrols.Handler
 
 	// duckAmount is the attenuation currently applied on top of the
@@ -63,6 +76,19 @@ type Player struct {
 	// not something the user chose.
 	duckAmount float64
 
+	// systemVolume is what SystemOwnsVolume answers: the platform's own
+	// control is the only one, so ours neither acts nor persists.  It is
+	// a field rather than the build constant read directly so that a
+	// test can exercise both sides on any machine.  See systemvolume.go.
+	systemVolume bool
+
+	// storedVolume and storedMuted hold the persisted level as it was
+	// found at restore, for a platform whose volume we do not own: the
+	// maximum we then run at is not a level the user chose, so saveState
+	// writes back what it read rather than overwriting it.
+	storedVolume UserVolume
+	storedMuted  bool
+
 	// trackLengthMs holds the authoritative track duration in
 	// milliseconds, sourced from the database (which uses the
 	// custom header parser).  The go-mp3 decoder's Len() can be
@@ -148,6 +174,8 @@ func NewPlayer(logger *slog.Logger, db *database.DB) *Player {
 		logger:       logger,
 		db:           db,
 		state:        Stopped,
+		systemVolume: platformOwnsVolume,
+		storedVolume: DefaultUserVol,
 		baseStreamer: generators.Silence(-1),
 		format: beep.Format{
 			SampleRate: speakerSampleRate,
@@ -180,11 +208,18 @@ func (p *Player) InitSpeaker() error {
 }
 
 // SetPlaybackFinishedHandler sets a callback invoked when a track
-// finishes naturally. This allows the queue to drive auto-advance
+// stops streaming. This allows the queue to drive auto-advance
 // without circular imports.
 //
+// The error says *why* the track stopped: nil for a track that
+// reached its end, non-nil for one that broke partway through.  Both
+// arrive here because both look identical to the speaker, and only
+// the queue holds the metadata a PlaybackFailed needs -- but they are
+// not the same event, and reporting a decode failure as a natural
+// finish is how a broken file used to auto-advance in silence.
+//
 //wails:ignore // internal wiring, not part of the app's IPC surface.
-func (p *Player) SetPlaybackFinishedHandler(handler func()) {
+func (p *Player) SetPlaybackFinishedHandler(handler func(error)) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
 
@@ -262,9 +297,78 @@ func (p *Player) emitPositionIfPlaying() {
 		return
 	}
 
+	p.reportUnderrunsLocked()
 	p.emitPositionLocked()
 }
 
+// underrunDelta is what happened since the last report.
+//
+// It clamps at zero rather than subtracting blind, because the counter
+// belongs to the *streamer* and the streamer is replaced on every
+// track: a baseline carried across that boundary is the previous
+// track's total subtracted from a fresh zero, which is negative. That
+// is repaired at the load (lastUnderruns is reset with the streamer)
+// and clamped here as well, because a negative count in a log line
+// reads as a broken instrument and would discredit the measurement
+// this exists to make.
+func underrunDelta(now, last UnderrunStats) UnderrunStats {
+	return UnderrunStats{
+		Runs:    max(0, now.Runs-last.Runs),
+		Calls:   max(0, now.Calls-last.Calls),
+		Samples: max(0, now.Samples-last.Samples),
+	}
+}
+
+// reportUnderrunsLocked logs what the ring buffer missed, at most once
+// a second and only when the number moved.  Must be called with p.mu
+// held.
+//
+// **An underrun is audible and nothing counted it** (#135). The ring
+// serves silence when it is empty, so a run of zeros is spliced into
+// the waveform and the step discontinuity at each edge is a click; a
+// series of short ones is static. Everything that makes one likelier
+// is worse on a phone than on a desktop -- slower storage, a governor
+// that parks cores, background work, GC -- and no tier here can see it,
+// since CI's audio device is a null sink chosen because it keeps time.
+//
+// Three things about the reporting are deliberate.
+//
+// **It is on the 1 Hz position ticker rather than in Stream.** Stream
+// runs on the speaker callback's real-time deadline, and a log line
+// there would allocate, format and write on the exact path whose
+// missed deadline is the defect -- measuring by making it worse.
+//
+// **An unchanged count is not logged.** That is emitStatus' rule one
+// package over: a healthy player is silent, so anything in the log is
+// news, and the line appears exactly while it is popping. Reading it
+// off a device means `make android-logs` with the audio audible.
+//
+// **It is Info rather than Debug**, because the default level is Info
+// and a phone has no convenient way to set YJ_LOG_LEVEL -- a debug
+// line here would be a counter nobody on the affected platform can
+// read, which is the shape of the bug that made #160 necessary.
+func (p *Player) reportUnderrunsLocked() {
+	if p.buffered == nil {
+		return
+	}
+
+	stats := p.buffered.Underruns()
+	if stats == p.lastUnderruns {
+		return
+	}
+
+	since := underrunDelta(stats, p.lastUnderruns)
+	p.lastUnderruns = stats
+
+	slog.Info("audio underrun",
+		"runs", since.Runs,
+		"calls", since.Calls,
+		"silenceMs", speakerSampleRate.D(int(since.Samples)).Milliseconds(),
+		"trackRuns", stats.Runs,
+		"trackSilenceMs", speakerSampleRate.D(int(stats.Samples)).Milliseconds(),
+	)
+}
+
 // emitPositionLocked pushes the current position to the frontend.
 // Must be called with p.mu held.
 func (p *Player) emitPositionLocked() {
@@ -424,6 +528,19 @@ func (p *Player) updateStreamers(
 	newBaseStreamer beep.StreamSeeker,
 	sr beep.SampleRate,
 ) error {
+	// A new chain supersedes the old one, so any finished callback the
+	// old one still owes is stale from here on.
+	p.chainID++
+
+	// The previous read-ahead goroutine reads the same decoder this
+	// one is about to, under its own srcMu -- two goroutines, two
+	// mutexes, one decoder that is not safe for concurrent use.  The
+	// replay-after-finish path rebuilds from p.seeker without going
+	// through LoadFile, which is where that pair could meet.
+	if p.buffered != nil {
+		p.buffered.Close()
+	}
+
 	// set base streamer
 	p.baseStreamer = newBaseStreamer
 	p.seeker = newBaseStreamer
@@ -441,6 +558,12 @@ func (p *Player) updateStreamers(
 		p.resampled, int(speakerSampleRate)*2,
 	)
 
+	// The counter belongs to the streamer, so the baseline it is
+	// reported against has to go with it -- otherwise the first report
+	// of a new track is the previous track's total subtracted from
+	// zero, which is negative and looks like the instrument is broken.
+	p.lastUnderruns = UnderrunStats{}
+
 	// wrap in ctrl streamer to allow play/pause
 	p.control = &beep.Ctrl{Streamer: p.buffered}
 
@@ -474,23 +597,57 @@ func (p *Player) startPaused() {
 	p.control.Paused = true
 	speaker.Unlock()
 
+	// Captured, not read at callback time: by then p.chainID names
+	// whatever is loaded *now*, which is the thing the guard exists to
+	// distinguish this chain from.
+	chainID := p.chainID
+	buffered := p.buffered
+
 	// The beep.Callback runs with the speaker mutex held, so we
 	// dispatch to a goroutine that can safely acquire p.mu.
 	speaker.Play(beep.Seq(
 		p.speakerStreamer,
 		beep.Callback(func() {
-			go p.onPlaybackFinished()
+			// Asked here rather than under p.mu: this is the chain that
+			// just ended, and by the time the goroutine holds the lock
+			// p.buffered may be a different one.
+			var err error
+			if buffered != nil {
+				err = buffered.Err()
+			}
+
+			go p.onPlaybackFinished(chainID, err)
 		}),
 	))
 
 	p.state = Paused
 }
 
-// onPlaybackFinished handles the natural end of a track. It is
-// called on a new goroutine from the beep callback (which holds
-// the speaker lock) so that it can safely acquire p.mu.
-func (p *Player) onPlaybackFinished() {
+// onPlaybackFinished handles a track that stopped streaming, whether
+// it ended or broke. It is called on a new goroutine from the beep
+// callback (which holds the speaker lock) so that it can safely
+// acquire p.mu.
+//
+// chainID names the streamer chain the callback fired for and srcErr
+// says why it stopped.
+func (p *Player) onPlaybackFinished(chainID uint64, srcErr error) {
 	p.mu.Lock()
+
+	// The player has moved on while this callback queued for the lock
+	// -- a user pressing Next during the last second of a track is
+	// enough. Everything below is about the *current* track: rewinding
+	// the decoder, saying playback stopped, asking the queue to
+	// advance. Doing any of it now would do it to the wrong track.
+	if chainID != p.chainID {
+		p.mu.Unlock()
+		p.logger.Debug(
+			"Ignoring finished callback for a superseded chain",
+			"chain", chainID, "current", p.chainID,
+		)
+
+		return
+	}
+
 	p.state = Stopped
 	handler := p.playbackFinishedHandler
 	mc := p.mediaControls
@@ -501,10 +658,11 @@ func (p *Player) onPlaybackFinished() {
 	// the Stopped state anyway, so this only moves the decoder.
 	p.rewindLocked()
 	p.emitPositionLocked()
-	p.mu.Unlock()
 
-	// Emit Wails events outside the lock — these are non-blocking
-	// calls that don't need player state.
+	// Emitted under p.mu, like every other transition in this file.
+	// Outside it, a Play() taking the lock in the gap emits `playing`
+	// first and this stale `stopped` lands last -- leaving the button
+	// showing play over a track that is audibly running.
 	p.emitPlaybackFinished()
 
 	events.Emit(
@@ -513,6 +671,8 @@ func (p *Player) onPlaybackFinished() {
 		map[string]string{"state": string(Stopped)},
 	)
 
+	p.mu.Unlock()
+
 	// Notify media controls outside the lock. The track just
 	// ended so position is 0.
 	if mc != nil {
@@ -521,12 +681,19 @@ func (p *Player) onPlaybackFinished() {
 		)
 	}
 
+	if srcErr != nil {
+		p.logger.Error(
+			"Playback stopped: the audio source failed",
+			"err", srcErr,
+		)
+	} else {
 		p.logger.Info("Playback finished naturally")
+	}
 
 	// Notify queue for auto-advance. Called without p.mu held
 	// because it re-enters the player via LoadFile/Play.
 	if handler != nil {
-		handler()
+		handler(srcErr)
 	}
 }
 
@@ -587,6 +754,18 @@ func (p *Player) loadFileLocked(filePath string) error {
 
 	p.currentFile = f
 
+	// The decoder's own format, kept for the paths that rebuild the
+	// chain later: Play()'s replay branch resamples from it, so a
+	// stale rate there plays a finished track back at the wrong speed.
+	p.format = format
+
+	// The previous track's duration must not outlive it.  This is set
+	// again by emitTrackChanged below, but only when the database has
+	// a row for the file -- and every position this player reports is
+	// scaled by it, so inheriting means every report is wrong by the
+	// ratio between two unrelated tracks.
+	p.trackLengthMs = 0
+
 	if err := p.updateStreamers(
 		streamer, format.SampleRate,
 	); err != nil {
@@ -791,6 +970,10 @@ func (p *Player) SetVolume(desiredVolume UserVolume) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
 
+	if p.systemVolume {
+		return
+	}
+
 	p.setVolumeLocked(desiredVolume)
 	p.emitVolumeChanged()
 	p.saveState()
@@ -839,6 +1022,10 @@ func (p *Player) ChangeVolume(deltaVolume int) error {
 	p.mu.Lock()
 	defer p.mu.Unlock()
 
+	if p.systemVolume {
+		return nil
+	}
+
 	p.setVolumeLocked(p.getUserVolume() + UserVolume(deltaVolume))
 	p.emitVolumeChanged()
 	p.saveState()
@@ -869,6 +1056,14 @@ func (p *Player) MuteToggle() error {
 		return errNoAudioFileLoaded
 	}
 
+	// Mute is a level of zero by another name, so it goes with the rest
+	// of the volume where the system owns it -- and it would be the one
+	// state on such a platform the user could not get out of, since with
+	// no control rendered there is nothing left to un-mute with.
+	if p.systemVolume {
+		return nil
+	}
+
 	speaker.Lock()
 	p.volume.Silent = !p.volume.Silent
 	speaker.Unlock()
@@ -906,6 +1101,8 @@ func (p *Player) CurrentPosition() (int, error) {
 		return 0, errNoAudioFileLoaded
 	}
 
+	defer p.lockSourceLocked()()
+
 	speaker.Lock()
 	pos := math.Round(
 		100.0 * float64(p.seeker.Position()) /
@@ -924,6 +1121,28 @@ func (p *Player) Seek(targetSeconds int) error {
 	return p.seekLocked(targetSeconds)
 }
 
+// lockSourceLocked blocks the read-ahead goroutine from touching the
+// decoder and returns the function that releases it, so a caller can
+// `defer p.lockSourceLocked()()`.
+//
+// Reading the decoder's position is a read *of the decoder*, and the
+// speaker lock does not exclude the read-ahead goroutine -- it never
+// takes it.  That was a genuine data race on every position emit,
+// once a second for the whole of playback.
+//
+// srcMu is not reentrant, so nothing that already holds it may call
+// this; seekSourceLocked exists to keep that region free of emits.
+// Must be called with p.mu held.
+func (p *Player) lockSourceLocked() func() {
+	if p.buffered == nil {
+		return func() {}
+	}
+
+	p.buffered.LockSource()
+
+	return p.buffered.UnlockSource
+}
+
 // rewindLocked returns the decoder to the start of the track without
 // touching playback state.  Must be called with p.mu held.
 func (p *Player) rewindLocked() {
@@ -959,6 +1178,46 @@ func (p *Player) seekLocked(targetSeconds int) error {
 		return fmt.Errorf("cannot get track length: %w", err)
 	}
 
+	// The source lock is released before anything below is emitted:
+	// emitPositionLocked reads the decoder's position and takes the
+	// same lock, which is not reentrant.
+	seekErr := p.seekSourceLocked(targetSeconds, lengthSecs)
+	if seekErr != nil {
+		p.logger.Warn(
+			"Seek failed, playback will start from "+
+				"the beginning",
+			"target-seconds", targetSeconds,
+			"err", seekErr,
+		)
+
+		// The optimistic move the UI already made has to be taken
+		// back, and only the backend knows it did not happen.
+		events.Emit(p.ctx, events.SeekFailed)
+		p.emitPositionLocked()
+
+		return fmt.Errorf("failed to seek: %w", seekErr)
+	}
+
+	if p.mediaControls != nil {
+		p.mediaControls.NotifySeek(targetSeconds)
+	}
+
+	// Report the landing position immediately rather than leaving the
+	// UI to guess until the next tick — this is the half of H-3 that
+	// desynced the seek bar by 30 s over four keyboard seeks.
+	p.emitPositionLocked()
+
+	return nil
+}
+
+// seekSourceLocked moves the decoder and flushes the stale read-ahead
+// behind it.  It owns the source lock for exactly that long and
+// emits nothing, so its caller is free to read the position
+// afterwards.  Must be called with p.mu held.
+func (p *Player) seekSourceLocked(
+	targetSeconds int,
+	lengthSecs int,
+) error {
 	// Block the read-ahead goroutine from reading the source while
 	// we seek it. The decoder (e.g. FLAC's bufseekio.ReadSeeker) is
 	// not safe for concurrent Read+Seek, and read-ahead runs on its
@@ -1014,19 +1273,11 @@ func (p *Player) seekLocked(targetSeconds int) error {
 	if seekErr != nil {
 		speaker.Unlock()
 
-		p.logger.Warn(
-			"Seek failed, playback will start from "+
-				"the beginning",
-			"target-seconds", targetSeconds,
-			"samples", samples,
-			"err", seekErr,
+		p.logger.Debug(
+			"seek rejected by the decoder",
+			"samples", samples, "err", seekErr,
 		)
 
-		// The optimistic move the UI already made has to be taken
-		// back, and only the backend knows it did not happen.
-		events.Emit(p.ctx, events.SeekFailed)
-		p.emitPositionLocked()
-
 		return fmt.Errorf("failed to seek: %w", seekErr)
 	}
 
@@ -1039,15 +1290,6 @@ func (p *Player) seekLocked(targetSeconds int) error {
 		p.buffered.Flush()
 	}
 
-	if p.mediaControls != nil {
-		p.mediaControls.NotifySeek(targetSeconds)
-	}
-
-	// Report the landing position immediately rather than leaving the
-	// UI to guess until the next tick — this is the half of H-3 that
-	// desynced the seek bar by 30 s over four keyboard seeks.
-	p.emitPositionLocked()
-
 	return nil
 }
 
@@ -1140,6 +1382,10 @@ func (p *Player) seekerLengthSecsLocked() (int, error) {
 		return 0, errNoAudioFileLoaded
 	}
 
+	// Len is fixed for the life of the decoder, so unlike Position it
+	// races with nothing and needs no source lock -- which it must not
+	// take anyway: displayPositionSecsLocked calls this while holding
+	// it, and srcMu is not reentrant.
 	speaker.Lock()
 	length := p.seeker.Len() / int(p.format.SampleRate)
 	speaker.Unlock()
@@ -1156,6 +1402,8 @@ func (p *Player) displayPositionSecsLocked() int {
 		return 0
 	}
 
+	defer p.lockSourceLocked()()
+
 	speaker.Lock()
 	pos := p.seeker.Position()
 	total := p.seeker.Len()
@@ -1266,7 +1514,15 @@ func (p *Player) saveState() {
 	volume := int64(DefaultUserVol)
 	muted := false
 
-	if p.volume != nil {
+	switch {
+	case p.systemVolume:
+		// The maximum this platform runs at is not a level anybody
+		// chose, so it is not one to remember.  Writing back what
+		// restore found keeps the row a description of the user's
+		// setting without needing a second query that omits the column.
+		volume = int64(p.storedVolume)
+		muted = p.storedMuted
+	case p.volume != nil:
 		volume = int64(p.getUserVolume())
 		muted = p.volume.Silent
 	}
@@ -1350,12 +1606,21 @@ func (p *Player) restoreStateLocked() {
 		}
 	}
 
+	if p.systemVolume {
+		// Remembered, not applied: the device's keys are the volume
+		// control here, so the player runs wide open and hands the
+		// stored level back untouched at the next save.
+		p.storedVolume = clampVolume(UserVolume(state.Volume))
+		p.storedMuted = state.Muted
+		p.setVolumeLocked(MaxUserVol)
+	} else {
 		vol := clampVolume(UserVolume(state.Volume))
 		p.setVolumeLocked(vol)
 
 		if state.Muted {
 			p.volume.Silent = true
 		}
+	}
 
 	// Restore last track if the file still exists.
 	if state.LastTrackPath != "" {
@@ -1394,8 +1659,9 @@ func (p *Player) restoreStateLocked() {
 	}
 
 	p.logger.Info("Player state restored",
-		"volume", vol,
-		"muted", state.Muted,
+		"volume", p.getUserVolume(),
+		"muted", p.volume.Silent,
+		"systemVolume", p.systemVolume,
 		"trackPath", state.LastTrackPath,
 		"positionSeconds", state.LastPositionSeconds,
 	)

backend/player/systemvolume.go

@@ -0,0 +1,42 @@
+package player
+
+// Who owns the volume, and what follows when it is not us.
+//
+// On Android the hardware keys *are* the volume control and the
+// framework mixes our stream against the device level, so a second
+// control inside the app is a slider that moves something the user
+// already moved (#64).  Where that is true the player's own level sits
+// at maximum, nothing changes it, and nothing persists it.
+//
+// **The predicate is named after the capability, not the platform.**
+// The frontend asks "is there a volume for me to control", which is a
+// question about this build; asking "is this a phone" instead would
+// key the answer to a viewport, and an Android tablet at 600px or more
+// would then draw the bottom bar's slider over a level pinned at
+// maximum -- a control that cannot act, which is the thing
+// `library-status-indicator` already settled is worse than none.
+//
+// **Only `platformOwnsVolume` is behind a build tag**, in two files
+// that declare nothing else.  A tagged file is compiled by nothing
+// `make lint` or `make test` runs and is untestable off a phone, which
+// is the reasoning `mediacontrols/androidpayload.go` states for
+// keeping its contract out of one -- so everything decidable here is
+// decided against `Player.systemVolume`, a field a test sets either
+// way, and the tag decides only what that field starts as.
+//
+// The one thing this must not disturb is ducking.  `SetDuck` applies
+// its attenuation by re-applying the *user's* level through
+// `setVolumeLocked`, so pinning that level to maximum leaves the
+// offset arithmetic exactly as it was: an OS asking us to get out of
+// the way of a navigation prompt is not the user setting a volume, and
+// it is the only thing that may move the output on such a platform.
+
+// SystemOwnsVolume reports whether the platform's own control is the
+// only volume control there is, so this app neither offers one nor
+// remembers a level.
+//
+// It is bound: the frontend renders no `<volume-control>` when it is
+// true, at any width.
+func (p *Player) SystemOwnsVolume() bool {
+	return p.systemVolume
+}

backend/player/systemvolume_android.go

@@ -0,0 +1,11 @@
+//go:build android
+
+package player
+
+// platformOwnsVolume is true on Android: volume is the device's, set
+// with the hardware keys, and `mediacontrols`' Android handler
+// implements no volume callback for the same reason.
+//
+// See systemvolume.go for why this constant is the whole of what a
+// build tag decides here.
+const platformOwnsVolume = true

backend/player/systemvolume_other.go

@@ -0,0 +1,10 @@
+//go:build !android
+
+package player
+
+// platformOwnsVolume is false everywhere but Android: a desktop mixer
+// is per-application, so our level is the one the user reaches for.
+//
+// See systemvolume.go for why this constant is the whole of what a
+// build tag decides here.
+const platformOwnsVolume = false

backend/player/systemvolume_test.go

@@ -0,0 +1,215 @@
+package player
+
+import (
+	"log/slog"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/gopxl/beep/v2/effects"
+
+	"yellowjacket/backend/database"
+)
+
+// pinnedPlayer is a player on a platform whose volume belongs to the
+// device.  The field is set rather than the build constant read,
+// because the constant is true on exactly one platform and no tier
+// here runs on it -- see systemvolume.go.
+func pinnedPlayer(t *testing.T, db *database.DB) *Player {
+	t.Helper()
+
+	p := NewPlayer(slog.Default(), db)
+	p.systemVolume = true
+	p.volume = &effects.Volume{Base: 2}
+	p.setVolumeLocked(MaxUserVol)
+
+	return p
+}
+
+// TestSystemVolumeRefusesEveryWayToChangeTheLevel is the first half of
+// #64: where the device owns the volume, ours sits at maximum and none
+// of the three routes to a level moves it.  Mute is in that list
+// because it is a level of zero by another name, and because with no
+// control rendered it is the one state on such a platform there would
+// be nothing to get out of.
+func TestSystemVolumeRefusesEveryWayToChangeTheLevel(t *testing.T) {
+	t.Parallel()
+
+	p := pinnedPlayer(t, nil)
+
+	if !p.SystemOwnsVolume() {
+		t.Fatal("SystemOwnsVolume() = false on a pinned player")
+	}
+
+	if got := p.getUserVolume(); got != MaxUserVol {
+		t.Errorf("starting volume = %d, want %d", got, MaxUserVol)
+	}
+
+	p.SetVolume(20)
+
+	if got := p.getUserVolume(); got != MaxUserVol {
+		t.Errorf("volume after SetVolume(20) = %d, want %d", got, MaxUserVol)
+	}
+
+	if err := p.ChangeVolume(-30); err != nil {
+		t.Fatalf("ChangeVolume: %v", err)
+	}
+
+	if got := p.getUserVolume(); got != MaxUserVol {
+		t.Errorf("volume after ChangeVolume(-30) = %d, want %d", got, MaxUserVol)
+	}
+
+	if err := p.MuteToggle(); err != nil {
+		t.Fatalf("MuteToggle: %v", err)
+	}
+
+	if p.volume.Silent {
+		t.Error("MuteToggle silenced a player whose volume the system owns")
+	}
+}
+
+// TestAnUnpinnedPlayerStillChangesItsVolume is the other side of the
+// same switch.  Without it the test above passes on a player that
+// refuses everything, which is what a mis-wired field would produce.
+func TestAnUnpinnedPlayerStillChangesItsVolume(t *testing.T) {
+	t.Parallel()
+
+	p := NewPlayer(slog.Default(), nil)
+	p.volume = &effects.Volume{Base: 2}
+	p.setVolumeLocked(MaxUserVol)
+
+	if p.SystemOwnsVolume() {
+		t.Fatal("SystemOwnsVolume() = true off Android")
+	}
+
+	p.SetVolume(20)
+
+	if got := p.getUserVolume(); got != 20 {
+		t.Errorf("volume after SetVolume(20) = %d, want 20", got)
+	}
+
+	if err := p.MuteToggle(); err != nil {
+		t.Fatalf("MuteToggle: %v", err)
+	}
+
+	if !p.volume.Silent {
+		t.Error("MuteToggle did not silence an ordinary player")
+	}
+}
+
+// TestSystemVolumeStillDucks is the issue's second Finding, made a
+// test: pinning the user's level must leave the OS's attenuation
+// working, because a duck is not a volume the user chose and is the
+// only thing that may move the output on such a platform.
+func TestSystemVolumeStillDucks(t *testing.T) {
+	t.Parallel()
+
+	p := pinnedPlayer(t, nil)
+	open := p.volume.Volume
+
+	p.SetDuck(true)
+
+	if p.volume.Volume >= open {
+		t.Errorf(
+			"ducked output = %v, want less than %v", p.volume.Volume, open,
+		)
+	}
+
+	if got := p.getUserVolume(); got != MaxUserVol {
+		t.Errorf("user volume while ducked = %d, want %d", got, MaxUserVol)
+	}
+
+	// A refused SetVolume must not disturb the offset either: it
+	// returns before setVolumeLocked, which is what re-applies it.
+	ducked := p.volume.Volume
+
+	p.SetVolume(10)
+
+	if p.volume.Volume != ducked {
+		t.Errorf(
+			"output after a refused SetVolume = %v, want %v",
+			p.volume.Volume, ducked,
+		)
+	}
+
+	p.SetDuck(false)
+
+	if p.volume.Volume != open {
+		t.Errorf("output after unduck = %v, want %v", p.volume.Volume, open)
+	}
+}
+
+// TestSystemVolumeWritesBackTheLevelItFound is the rest of the
+// Direction: "make sure nothing writes a persisted volume from that
+// platform".  The maximum the player runs at is synthetic, so saving
+// must not record it over whatever the row already said.
+func TestSystemVolumeWritesBackTheLevelItFound(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+
+	// A level set by some earlier, unpinned session.
+	writer := NewPlayer(slog.Default(), db)
+	writer.volume = &effects.Volume{Base: 2}
+	writer.setVolumeLocked(30)
+	writer.SaveState()
+
+	p := pinnedPlayer(t, db)
+	p.RestoreState()
+
+	if got := p.getUserVolume(); got != MaxUserVol {
+		t.Errorf("restored volume = %d, want %d (the level is pinned)", got, MaxUserVol)
+	}
+
+	if p.volume.Silent {
+		t.Error("restore muted a player whose volume the system owns")
+	}
+
+	p.SaveState()
+
+	state, err := db.Queries.GetPlayerState(db.Ctx)
+	if err != nil {
+		t.Fatalf("GetPlayerState: %v", err)
+	}
+
+	if state.Volume != 30 {
+		t.Errorf("persisted volume = %d, want 30 (untouched)", state.Volume)
+	}
+}
+
+// TestPlatformVolumeOwnershipIsDeclaredOncePerPlatform sweeps the
+// source, because the pair of tagged files is the one thing here no
+// tier compiles both halves of: `make lint` and `make test` build the
+// `!android` side only, so a deleted or edited android file fails
+// nothing until somebody has a phone in their hand.
+func TestPlatformVolumeOwnershipIsDeclaredOncePerPlatform(t *testing.T) {
+	t.Parallel()
+
+	want := map[string]string{
+		"systemvolume_other.go":   "const platformOwnsVolume = false",
+		"systemvolume_android.go": "const platformOwnsVolume = true",
+	}
+
+	tags := map[string]string{
+		"systemvolume_other.go":   "//go:build !android",
+		"systemvolume_android.go": "//go:build android",
+	}
+
+	for name, decl := range want {
+		src, err := os.ReadFile(filepath.Join(".", name))
+		if err != nil {
+			t.Errorf("%s: %v", name, err)
+
+			continue
+		}
+
+		if !strings.Contains(string(src), decl) {
+			t.Errorf("%s does not declare %q", name, decl)
+		}
+
+		if !strings.Contains(string(src), tags[name]) {
+			t.Errorf("%s does not carry %q", name, tags[name])
+		}
+	}
+}

backend/queue/emit.go

@@ -81,6 +81,7 @@ func (q *Queue) emitTracksModified(
 			Index:        index,
 			Positions:    positions,
 			CurrentIndex: q.currentIndex,
+			Source:       q.source,
 		},
 	)
 }

backend/queue/emit_test.go

@@ -219,6 +219,56 @@ func TestEmit_AddTrackSendsDeltaNotSnapshot(t *testing.T) {
 	}
 }
 
+// The append clears the source, and the delta is the only event those
+// paths emit — so if it does not carry the source, the frontend keeps
+// the label it was last given and goes on offering a link back to an
+// album the queue no longer holds until something forces a full state.
+func TestEmit_AppendDeltaCarriesClearedSource(t *testing.T) {
+	t.Parallel()
+
+	q, db, rec := setupRecordedQueue(t)
+	paths := seedAudioFiles(t, db, 4)
+
+	q.SetQueue(
+		paths[:3], 0, false,
+		Source{Type: "album", ID: 1, Label: "Abbey Road"},
+	)
+
+	if _, ok := rec.Wait(events.QueueChanged, waitFor); !ok {
+		t.Fatalf("no QueueChanged after SetQueue; got %v", rec.Names())
+	}
+
+	rec.Reset()
+	q.AddTrack(paths[3])
+
+	if got := modifiedOf(t, rec).Source; got != (Source{}) {
+		t.Errorf("delta source = %+v, want zero value", got)
+	}
+}
+
+// And a delta that did not clear it still reports the source it has,
+// or the frontend would drop a perfectly good label on every removal.
+func TestEmit_NonAppendDeltaCarriesSource(t *testing.T) {
+	t.Parallel()
+
+	q, db, rec := setupRecordedQueue(t)
+	paths := seedAudioFiles(t, db, 4)
+
+	album := Source{Type: "album", ID: 1, Label: "Abbey Road"}
+	q.SetQueue(paths, 0, false, album)
+
+	if _, ok := rec.Wait(events.QueueChanged, waitFor); !ok {
+		t.Fatalf("no QueueChanged after SetQueue; got %v", rec.Names())
+	}
+
+	rec.Reset()
+	q.RemoveTrack(3)
+
+	if got := modifiedOf(t, rec).Source; got != album {
+		t.Errorf("delta source = %+v, want %+v", got, album)
+	}
+}
+
 func TestEmit_RemoveTracksReportsPositions(t *testing.T) {
 	t.Parallel()
 

backend/queue/fallback_test.go

@@ -83,7 +83,7 @@ func TestFallback_TriggersOnNaturalFinish(t *testing.T) {
 	q.SetFallbackSource(fake)
 
 	q.SetQueue(seedPaths, 0, false, Source{Type: "album", ID: 1, Label: "Seed Album"})
-	q.OnPlaybackFinished()
+	q.OnPlaybackFinished(nil)
 
 	waitUntil(t, func() bool { return fake.callCount() == 1 }, "fallback to be resolved")
 	waitUntil(t, func() bool {
@@ -159,7 +159,7 @@ func TestFallback_EmptyResultLeavesQueueExhausted(t *testing.T) {
 	q.SetFallbackSource(fake)
 
 	q.SetQueue(seedPaths, 0, false, Source{})
-	q.OnPlaybackFinished()
+	q.OnPlaybackFinished(nil)
 
 	waitUntil(t, func() bool { return fake.callCount() == 1 }, "fallback to be resolved")
 
@@ -193,7 +193,7 @@ func TestFallback_StaleResolutionDiscarded(t *testing.T) {
 	q.SetFallbackSource(fake)
 
 	q.SetQueue(seedPaths, 0, false, Source{})
-	q.OnPlaybackFinished() // starts resolving, blocked on gate
+	q.OnPlaybackFinished(nil) // starts resolving, blocked on gate
 
 	time.Sleep(20 * time.Millisecond) // let the goroutine reach the gate
 

backend/queue/finished_test.go

@@ -0,0 +1,78 @@
+package queue
+
+import (
+	"errors"
+	"testing"
+
+	"yellowjacket/backend/events"
+)
+
+// errTestDecode stands in for a decoder blowing up mid-track.
+var errTestDecode = errors.New("decode blew up")
+
+// currentIndex == -1 against a non-empty queue is a state this
+// package produces on purpose: onQueueExhausted(false) sets it and
+// deliberately leaves the finished track loaded in the player, so it
+// stays on the now-playing bar. Pressing play from there and letting
+// it finish re-enters OnPlaybackFinished with exactly that pair --
+// which used to index q.tracks[-1] and panic, on a goroutine
+// dispatched from the audio callback with no caller to recover it.
+func TestFinishedWithNoCurrentTrackDoesNotPanic(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name  string
+		index int
+	}{
+		{"exhausted queue leaves -1", -1},
+		{"index past the end", 3},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			q, _, _ := setupRecordedQueue(t)
+			q.tracks = []Track{
+				{FilePath: "/a.mp3"},
+				{FilePath: "/b.mp3"},
+			}
+			q.currentIndex = tt.index
+
+			// The assertion is that this returns at all.
+			q.OnPlaybackFinished(nil)
+
+			if q.currentIndex != tt.index {
+				t.Errorf(
+					"an out-of-range index was acted on: %d became %d",
+					tt.index, q.currentIndex,
+				)
+			}
+		})
+	}
+}
+
+// A track that broke mid-playback is not a track that was listened
+// to. The player cannot say so itself -- the metadata is here -- so
+// it hands the reason over and this is where it becomes a
+// PlaybackFailed rather than a silent auto-advance.
+func TestAFailedTrackIsReportedAndNotCountedAsAPlay(t *testing.T) {
+	t.Parallel()
+
+	q, _, rec := setupRecordedQueue(t)
+	q.tracks = []Track{
+		{FilePath: "/a.mp3", Title: "A", AudioFileID: 1},
+		{FilePath: "/b.mp3", Title: "B", AudioFileID: 2},
+	}
+	q.currentIndex = 0
+
+	q.OnPlaybackFinished(errTestDecode)
+
+	if _, ok := rec.Last(events.PlaybackFailed); !ok {
+		t.Errorf(
+			"a track that failed mid-playback told the user nothing; "+
+				"got %v",
+			rec.Names(),
+		)
+	}
+}

backend/queue/handlers.go

@@ -1,18 +1,45 @@
 package queue
 
-// OnPlaybackFinished is called when a track finishes playing naturally.
-// This drives the auto-advance behavior and records the play.
-func (q *Queue) OnPlaybackFinished() {
+// OnPlaybackFinished is called when a track stops streaming. This
+// drives the auto-advance behavior and records the play.
+//
+// srcErr says why the track stopped: nil for one that reached its
+// end, non-nil for one that broke partway through.  The player cannot
+// tell the user which, because the metadata lives here -- so a failure
+// is reported as PlaybackFailed and *not* recorded as a play, while
+// the advance happens either way.  Before this, a file that failed
+// mid-track advanced in silence and was counted as listened to.
+//
+//wails:ignore // internal wiring, not part of the app's IPC surface.
+func (q *Queue) OnPlaybackFinished(srcErr error) {
 	q.mu.Lock()
 
-	if len(q.tracks) == 0 {
+	// currentIndex is -1 whenever the queue has been exhausted, and
+	// onQueueExhausted deliberately leaves the finished track loaded
+	// in the player -- so a natural finish can re-enter here against a
+	// queue that is not empty and an index that is not valid.  Every
+	// other path in this package bounds-checks before indexing; this
+	// one panicked, on a goroutine with no caller to recover it.
+	if q.currentIndex < 0 || q.currentIndex >= len(q.tracks) {
 		q.mu.Unlock()
 
 		return
 	}
 
 	// Capture the track that just finished before advancing.
-	finishedID := q.tracks[q.currentIndex].AudioFileID
+	finished := q.tracks[q.currentIndex]
+	finishedID := finished.AudioFileID
+
+	if srcErr != nil {
+		q.emitPlaybackFailed(finished, srcErr)
+	}
+
+	// A track that broke was not listened to.
+	recordFinished := func() {
+		if srcErr == nil {
+			q.recordPlay(finishedID)
+		}
+	}
 
 	// Repeat One: replay the current track.
 	if q.repeatMode == RepeatOne {
@@ -21,7 +48,7 @@ func (q *Queue) OnPlaybackFinished() {
 		}
 
 		q.mu.Unlock()
-		q.recordPlay(finishedID)
+		recordFinished()
 
 		return
 	}
@@ -31,7 +58,7 @@ func (q *Queue) OnPlaybackFinished() {
 		// Queue exhausted — this is the extension point for a future fallback playlist.
 		q.onQueueExhausted(false)
 		q.mu.Unlock()
-		q.recordPlay(finishedID)
+		recordFinished()
 
 		return
 	}
@@ -44,12 +71,12 @@ func (q *Queue) OnPlaybackFinished() {
 	if !q.playCurrentOrSkip(true, q.nextIndex) {
 		q.onQueueExhausted(false)
 		q.mu.Unlock()
-		q.recordPlay(finishedID)
+		recordFinished()
 
 		return
 	}
 
 	q.emitIndexChanged()
 	q.mu.Unlock()
-	q.recordPlay(finishedID)
+	recordFinished()
 }

backend/queue/playbackfailed_test.go

@@ -107,7 +107,7 @@ func TestPlaybackFailed_AutoAdvanceSkipsPastIt(t *testing.T) {
 
 	// The first track finished: auto-advance lands on the missing
 	// file and must step over it rather than stopping dead.
-	q.OnPlaybackFinished()
+	q.OnPlaybackFinished(nil)
 
 	if got := q.GetState().CurrentIndex; got != 2 {
 		t.Errorf("currentIndex after skipping: got %d, want 2", got)
@@ -183,7 +183,7 @@ func TestQueueExhausted_KeepsTheFinishedTrackLoaded(t *testing.T) {
 
 	q.SetQueue(paths, 0, false, Source{})
 	q.Play()
-	q.OnPlaybackFinished()
+	q.OnPlaybackFinished(nil)
 
 	if q.GetState().CurrentIndex != -1 {
 		t.Errorf(

backend/queue/queue.go

@@ -156,12 +156,21 @@ type PlaybackFailure struct {
 }
 
 // TracksModified is the payload for the QueueTracksModified event.
+//
+// Source is carried because an append is exactly what can *invalidate*
+// it: a queue built from one album stops being that album the moment a
+// track from somewhere else is added to it. The delta is the only event
+// those paths emit, so without this the frontend would keep the label
+// it was last given and go on saying "Playing from" an album that is no
+// longer what is queued — an event carrying what its consumer needs, so
+// nothing has to invalidate anything.
 type TracksModified struct {
 	Action       string  `json:"action"`
 	Tracks       []Track `json:"tracks,omitempty"`
 	Index        int     `json:"index"`
 	Positions    []int   `json:"positions,omitempty"`
 	CurrentIndex int     `json:"currentIndex"`
+	Source       Source  `json:"source"`
 }
 
 // Queue manages an ordered list of tracks for playback.
@@ -455,6 +464,8 @@ func (q *Queue) AddTrack(filePath string) {
 		q.generateShuffleOrder()
 	}
 
+	q.dropSource()
+
 	q.persistAddTrack(track)
 	q.persistState()
 	q.emitTracksModified(
@@ -505,6 +516,8 @@ func (q *Queue) AddTracks(filePaths []string) {
 		q.generateShuffleOrder()
 	}
 
+	q.dropSource()
+
 	q.persistAddTracks(newTracks)
 	q.persistState()
 	q.emitTracksModified(
@@ -563,6 +576,8 @@ func (q *Queue) InsertNextTracks(filePaths []string) {
 		q.generateShuffleOrder()
 	}
 
+	q.dropSource()
+
 	q.persistInsertTracks(newTracks, insertPos)
 	q.persistState()
 	q.emitTracksModified(
@@ -613,6 +628,8 @@ func (q *Queue) InsertNext(filePath string) {
 		q.generateShuffleOrder()
 	}
 
+	q.dropSource()
+
 	q.persistInsertTracks([]Track{track}, insertPos)
 	q.persistState()
 	q.emitTracksModified(
@@ -680,6 +697,8 @@ func (q *Queue) InsertTracksAt(filePaths []string, index int) {
 		q.generateShuffleOrder()
 	}
 
+	q.dropSource()
+
 	q.persistInsertTracks(newTracks, index)
 	q.persistState()
 	q.emitTracksModified(
@@ -1537,6 +1556,31 @@ func (q *Queue) reindexPositions() {
 	}
 }
 
+// dropSource forgets which collection the queue was built from.
+//
+// A Source is a claim that everything queued came from one album,
+// playlist, genre or artist, and the frontend renders it as a
+// "Playing from X" link back to that page. Adding or inserting a track
+// makes the claim false — the queue is now that album *plus* something
+// else — so every path that does so calls this.
+//
+// It was set by SetQueue and cleared in exactly one place, Clear, so a
+// label survived every append. It is persisted too (source_type /
+// source_id / source_label on the queue state row), which is what made
+// a wrong label outlive the session that earned it: an album queued on
+// Monday, added to on Tuesday, still offered a link back to that album
+// on Friday.
+//
+// Removing, reordering and shuffling deliberately do not call this. A
+// queue with a track taken out of it, or played in another order, is
+// still that album — the link still goes somewhere true. Only the
+// arrival of a track from elsewhere makes it a lie.
+//
+// The caller must hold q.mu.
+func (q *Queue) dropSource() {
+	q.source = Source{}
+}
+
 // commitMutation persists the current queue state after a mutation.
 // When reindex is true, track positions are renumbered first.
 // The caller must hold q.mu.

backend/queue/queue_test.go

@@ -126,6 +126,117 @@ func TestClear_ResetsSource(t *testing.T) {
 	}
 }
 
+// A queue built from one album stops being that album the moment a
+// track from somewhere else joins it, so every path that adds one
+// drops the source. Before this, SetQueue was the only writer and
+// Clear the only clearer, so "Playing from Abbey Road" outlived every
+// append — and, being persisted, every restart too.
+func TestAppendPathsDropSource(t *testing.T) {
+	t.Parallel()
+
+	album := Source{Type: "album", ID: 1, Label: "Abbey Road"}
+
+	tests := []struct {
+		name   string
+		append func(q *Queue, paths []string)
+	}{
+		{
+			name: "AddTrack",
+			append: func(q *Queue, paths []string) {
+				q.AddTrack(paths[5])
+			},
+		},
+		{
+			name: "AddTracks",
+			append: func(q *Queue, paths []string) {
+				q.AddTracks(paths[5:7])
+			},
+		},
+		{
+			name: "InsertNext",
+			append: func(q *Queue, paths []string) {
+				q.InsertNext(paths[5])
+			},
+		},
+		{
+			name: "InsertNextTracks",
+			append: func(q *Queue, paths []string) {
+				q.InsertNextTracks(paths[5:7])
+			},
+		},
+		{
+			name: "InsertTracksAt",
+			append: func(q *Queue, paths []string) {
+				q.InsertTracksAt(paths[5:7], 1)
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			q, db := setupTestQueue(t)
+			paths := seedAudioFiles(t, db, 8)
+
+			q.SetQueue(paths[:5], 0, false, album)
+
+			if got := q.GetState().Source; got != album {
+				t.Fatalf("source before append: got %+v, want %+v", got, album)
+			}
+
+			tt.append(q, paths)
+
+			if got := q.GetState().Source; got != (Source{}) {
+				t.Errorf(
+					"source after %s: got %+v, want zero value",
+					tt.name, got,
+				)
+			}
+		})
+	}
+}
+
+// Removing and reordering deliberately do not drop it: a queue with a
+// track taken out of it is still that album, and the link still goes
+// somewhere true.
+func TestRemoveAndMoveKeepSource(t *testing.T) {
+	t.Parallel()
+
+	album := Source{Type: "album", ID: 1, Label: "Abbey Road"}
+
+	t.Run("RemoveTrack", func(t *testing.T) {
+		t.Parallel()
+
+		q, db := setupTestQueue(t)
+		paths := seedAudioFiles(t, db, 5)
+
+		q.SetQueue(paths, 0, false, album)
+		q.RemoveTrack(3)
+
+		if got := q.GetState().Source; got != album {
+			t.Errorf("source after RemoveTrack: got %+v, want %+v", got, album)
+		}
+	})
+
+	t.Run("MoveQueueTracks", func(t *testing.T) {
+		t.Parallel()
+
+		q, db := setupTestQueue(t)
+		paths := seedAudioFiles(t, db, 5)
+
+		q.SetQueue(paths, 0, false, album)
+		q.MoveQueueTracks([]int{0}, 3)
+
+		if got := q.GetState().Source; got != album {
+			t.Errorf(
+				"source after MoveQueueTracks: got %+v, want %+v",
+				got, album,
+			)
+		}
+	})
+}
+
 func TestSetQueue_WithStartIndex(t *testing.T) {
 	t.Parallel()
 

backend/shortcuts/config.go

@@ -24,10 +24,19 @@ func DefaultBindings() map[string]string {
 		"player.repeat":      "R",
 		"player.mute":        "M",
 
-		// Navigation (Global scope)
+		// Navigation (Global scope).  Back and forward are the browser's
+		// own combination on every platform, which is the whole design
+		// brief for them: the app has one global history and this is the
+		// gesture people already have for it.  The modifier is what keeps
+		// them clear of `player.seekBack`/`seekForward`, which are the
+		// bare arrows -- a binding is matched on its full canonical
+		// string, so "Alt+Left" and "Left" are different keys and not a
+		// conflict.
 		"nav.search":    "/",
 		"nav.searchAlt": "Ctrl+F",
 		"nav.queue":     "Q",
+		"nav.back":      "Alt+Left",
+		"nav.forward":   "Alt+Right",
 
 		// App actions
 		"app.selectAll": "Ctrl+A",

backend/smartplaylist/smartplaylist.go

@@ -28,6 +28,7 @@ var (
 	errUnsupportedOp    = errors.New("unsupported operator")
 	errInvalidSortField = errors.New("invalid sort field: not in allowed field list")
 	errNotNumeric       = errors.New("value must be numeric")
+	errInvalidMatch     = errors.New("match must be \"all\" or \"any\"")
 )
 
 // Rule represents a single filter condition for a smart playlist.
@@ -37,10 +38,42 @@ type Rule struct {
 	Value    string `json:"value"`
 }
 
+// MatchType decides how a rule set's conditions combine.
+//
+// The rules used to be joined with " AND " and nothing else, so a
+// playlist could only ever narrow: "jazz released after 1960" was
+// expressible and "jazz or blues" was not, which is most of what
+// anyone reaches for a second rule to say.
+type MatchType string
+
+const (
+	// MatchAll requires every rule to hold — the historical behaviour,
+	// and what an empty match means so that every rule set written
+	// before this existed keeps the meaning it was saved with.
+	MatchAll MatchType = "all"
+	// MatchAny requires at least one rule to hold.
+	MatchAny MatchType = "any"
+)
+
+// joiner returns the SQL keyword that combines two conditions.
+// An unrecognised value cannot reach here — ParseRuleSet rejects one
+// — so the default is about the empty string, which is every rule set
+// saved before this field existed.
+func (m MatchType) joiner() string {
+	if m == MatchAny {
+		return " OR "
+	}
+
+	return " AND "
+}
+
 // RuleSet holds the complete filter configuration for a smart
 // playlist, including optional sort and limit.
 type RuleSet struct {
 	Rules []Rule `json:"rules"`
+	// Match is "all" or "any"; empty means "all". It is omitempty so
+	// an untouched playlist's stored JSON does not change shape.
+	Match     MatchType `json:"match,omitempty"`
 	Limit     int       `json:"limit,omitempty"`
 	SortField string    `json:"sort_field,omitempty"`
 	SortDir   string    `json:"sort_dir,omitempty"`
@@ -116,7 +149,12 @@ const genreDelimiter = "||"
 // slice of rules. It is a pure function — no database access needed.
 // Returns the clause (without the leading "WHERE"), the parameter
 // args, and any validation error.
-func BuildWhereClause(rules []Rule) (string, []any, error) {
+//
+// match decides how the conditions combine; an empty match is MatchAll,
+// which is what every rule set saved before the field existed means.
+func BuildWhereClause(
+	rules []Rule, match MatchType,
+) (string, []any, error) {
 	if len(rules) == 0 {
 		return "", nil, nil
 	}
@@ -179,7 +217,28 @@ func BuildWhereClause(rules []Rule) (string, []any, error) {
 		args = append(args, condArgs...)
 	}
 
-	return strings.Join(conditions, " AND "), args, nil
+	// Under OR, each condition is parenthesised; under AND it is not.
+	//
+	// The asymmetry is deliberate rather than an omission. AND is the
+	// tighter operator in SQL, so an OR-join has to protect any
+	// condition that contains a top-level AND of its own or the halves
+	// come apart: `days_since_played less_than` is
+	// `last_played IS NOT NULL AND <expr> < ?`, which read without
+	// brackets under an OR-join happens to still parse correctly and
+	// would stop doing so the moment a condition grows a top-level OR.
+	// Bracketing under AND would be a no-op semantically and would
+	// rewrite the clause every existing test pins, so the brackets go
+	// exactly where they change something.
+	if match == MatchAny {
+		bracketed := make([]string, len(conditions))
+		for i, cond := range conditions {
+			bracketed[i] = "(" + cond + ")"
+		}
+
+		conditions = bracketed
+	}
+
+	return strings.Join(conditions, match.joiner()), args, nil
 }
 
 // validateOperator checks that the operator is valid for the field
@@ -599,7 +658,7 @@ func Evaluate(
 	start := time.Now()
 	logger := db.Logger()
 
-	where, args, err := BuildWhereClause(ruleSet.Rules)
+	where, args, err := BuildWhereClause(ruleSet.Rules, ruleSet.Match)
 	if err != nil {
 		return nil, fmt.Errorf(
 			"smart playlist rule error: %w", err,
@@ -1036,6 +1095,16 @@ func ParseRuleSet(jsonStr string) (RuleSet, error) {
 		)
 	}
 
+	// A match nobody recognises would otherwise fall through to AND,
+	// which is a playlist quietly returning the wrong tracks rather
+	// than refusing to be saved. This is the only place a rule set
+	// enters the backend, so it is the only place that has to ask.
+	if rs.Match != "" && rs.Match != MatchAll && rs.Match != MatchAny {
+		return RuleSet{}, fmt.Errorf(
+			"%w: %q", errInvalidMatch, rs.Match,
+		)
+	}
+
 	return rs, nil
 }
 

backend/smartplaylist/smartplaylist_test.go

@@ -1,6 +1,7 @@
 package smartplaylist
 
 import (
+	"errors"
 	"strings"
 	"testing"
 
@@ -170,7 +171,7 @@ func TestBuildWhereClause_TextIs(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "artist", Operator: "is", Value: "Queen"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -189,7 +190,7 @@ func TestBuildWhereClause_TextIsNot(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "artist", Operator: "is_not", Value: "Queen"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -209,7 +210,7 @@ func TestBuildWhereClause_TextContains(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "title", Operator: "contains", Value: "Black"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -231,7 +232,7 @@ func TestBuildWhereClause_TextDoesNotContain(t *testing.T) {
 			Field: "title", Operator: "does_not_contain",
 			Value: "Black",
 		},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -251,7 +252,7 @@ func TestBuildWhereClause_TextStartsWith(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "title", Operator: "starts_with", Value: "Back"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -270,7 +271,7 @@ func TestBuildWhereClause_TextEndsWith(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "title", Operator: "ends_with", Value: "Black"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -292,7 +293,7 @@ func TestBuildWhereClause_TextIsAnyOf(t *testing.T) {
 			Field: "artist", Operator: "is_any_of",
 			Value: `["Queen","AC/DC"]`,
 		},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -312,7 +313,7 @@ func TestBuildWhereClause_NumericIs(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "year", Operator: "is", Value: "1980"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -331,7 +332,7 @@ func TestBuildWhereClause_NumericIsNot(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "year", Operator: "is_not", Value: "1980"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -350,7 +351,7 @@ func TestBuildWhereClause_NumericGreaterThan(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "year", Operator: "greater_than", Value: "2000"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -369,7 +370,7 @@ func TestBuildWhereClause_NumericLessThan(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "year", Operator: "less_than", Value: "1980"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -391,7 +392,7 @@ func TestBuildWhereClause_NumericBetween(t *testing.T) {
 			Field: "year", Operator: "between",
 			Value: "1975,1985",
 		},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -414,7 +415,7 @@ func TestBuildWhereClause_NumericBetweenJSON(t *testing.T) {
 			Field: "year", Operator: "between",
 			Value: `["1975","1985"]`,
 		},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -434,7 +435,7 @@ func TestBuildWhereClause_GenreIsProducesSubquery(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "genre", Operator: "is", Value: "Rock"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -466,7 +467,7 @@ func TestBuildWhereClause_GenreIsNotProducesSubquery(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "genre", Operator: "is_not", Value: "Rock"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -495,7 +496,7 @@ func TestBuildWhereClause_GenreIsAnyOfProducesSubquery(t *testing.T) {
 			Field: "genre", Operator: "is_any_of",
 			Value: `["Rock","Pop"]`,
 		},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -524,7 +525,7 @@ func TestBuildWhereClause_GenreContainsUsesSubquery(t *testing.T) {
 
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "genre", Operator: "contains", Value: "Rock"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -557,7 +558,7 @@ func TestBuildWhereClause_MultipleRulesAND(t *testing.T) {
 	clause, args, err := BuildWhereClause([]Rule{
 		{Field: "artist", Operator: "is", Value: "Queen"},
 		{Field: "year", Operator: "greater_than", Value: "1975"},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -572,6 +573,110 @@ func TestBuildWhereClause_MultipleRulesAND(t *testing.T) {
 	}
 }
 
+func TestBuildWhereClause_MultipleRulesOR(t *testing.T) {
+	t.Parallel()
+
+	clause, args, err := BuildWhereClause([]Rule{
+		{Field: "artist", Operator: "is", Value: "Queen"},
+		{Field: "year", Operator: "greater_than", Value: "1975"},
+	}, MatchAny)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	want := "(artist_name = ? COLLATE NOCASE) OR (year > ?)"
+	if clause != want {
+		t.Errorf("clause = %q, want %q", clause, want)
+	}
+
+	if len(args) != 2 || args[0] != "Queen" || args[1] != int64(1975) {
+		t.Errorf("args = %v, want [Queen 1975]", args)
+	}
+}
+
+// An empty match is what every rule set saved before the field existed
+// carries, and it has to keep meaning AND — a playlist silently
+// widening to OR on upgrade is the whole risk of adding this field.
+func TestBuildWhereClause_EmptyMatchIsAll(t *testing.T) {
+	t.Parallel()
+
+	rules := []Rule{
+		{Field: "artist", Operator: "is", Value: "Queen"},
+		{Field: "year", Operator: "greater_than", Value: "1975"},
+	}
+
+	empty, _, err := BuildWhereClause(rules, "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	all, _, err := BuildWhereClause(rules, MatchAll)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if empty != all {
+		t.Errorf("empty match = %q, want the same as MatchAll %q",
+			empty, all)
+	}
+}
+
+// A condition carrying its own top-level AND is what makes the
+// bracketing under OR load-bearing: `days_since_played less_than`
+// is two predicates, and both belong to the same rule.
+func TestBuildWhereClause_ORBracketsCompoundCondition(t *testing.T) {
+	t.Parallel()
+
+	clause, _, err := BuildWhereClause([]Rule{
+		{Field: "artist", Operator: "is", Value: "Queen"},
+		{
+			Field:    "days_since_played",
+			Operator: "less_than",
+			Value:    "30",
+		},
+	}, MatchAny)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !strings.Contains(clause, "(last_played IS NOT NULL AND") {
+		t.Errorf(
+			"compound condition is not bracketed under OR: %q",
+			clause,
+		)
+	}
+}
+
+func TestParseRuleSet_RejectsUnknownMatch(t *testing.T) {
+	t.Parallel()
+
+	_, err := ParseRuleSet(`{"rules":[],"match":"either"}`)
+	if err == nil {
+		t.Fatal("expected an error for an unknown match type")
+	}
+
+	if !errors.Is(err, errInvalidMatch) {
+		t.Errorf("err = %v, want errInvalidMatch", err)
+	}
+}
+
+func TestParseRuleSet_AcceptsAnyAndAll(t *testing.T) {
+	t.Parallel()
+
+	for _, want := range []MatchType{MatchAll, MatchAny} {
+		rs, err := ParseRuleSet(
+			`{"rules":[],"match":"` + string(want) + `"}`,
+		)
+		if err != nil {
+			t.Fatalf("match %q: unexpected error: %v", want, err)
+		}
+
+		if rs.Match != want {
+			t.Errorf("match = %q, want %q", rs.Match, want)
+		}
+	}
+}
+
 func TestBuildWhereClause_SameFieldMultipleTimes(t *testing.T) {
 	t.Parallel()
 
@@ -581,7 +686,7 @@ func TestBuildWhereClause_SameFieldMultipleTimes(t *testing.T) {
 			Field: "genre", Operator: "does_not_contain",
 			Value: "Punk",
 		},
-	})
+	}, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -609,7 +714,7 @@ func TestBuildWhereClause_SameFieldMultipleTimes(t *testing.T) {
 func TestBuildWhereClause_EmptyRules(t *testing.T) {
 	t.Parallel()
 
-	clause, args, err := BuildWhereClause(nil)
+	clause, args, err := BuildWhereClause(nil, MatchAll)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -631,7 +736,7 @@ func TestBuildWhereClause_InvalidField(t *testing.T) {
 			Field: "nonexistent", Operator: "is",
 			Value: "anything",
 		},
-	})
+	}, MatchAll)
 	if err == nil {
 		t.Fatal("expected error for invalid field, got nil")
 	}
@@ -654,7 +759,7 @@ func TestBuildWhereClause_InvalidOperatorForNumeric(t *testing.T) {
 
 	_, _, err := BuildWhereClause([]Rule{
 		{Field: "year", Operator: "contains", Value: "1980"},
-	})
+	}, MatchAll)
 	if err == nil {
 		t.Fatal(
 			"expected error for text operator on numeric field",
@@ -676,7 +781,7 @@ func TestBuildWhereClause_InvalidOperatorForText(t *testing.T) {
 			Field: "artist", Operator: "greater_than",
 			Value: "Queen",
 		},
-	})
+	}, MatchAll)
 	if err == nil {
 		t.Fatal(
 			"expected error for numeric operator on text field",
@@ -723,6 +828,80 @@ func TestEvaluate_TextIs(t *testing.T) {
 	}
 }
 
+// Two rules that share no track at all: under AND this is empty, and
+// under OR it is the union. Before Match existed only the first was
+// expressible, so a playlist could only ever narrow — "jazz or blues"
+// had no way to be said.
+func TestEvaluate_MatchAnyUnionsWhereMatchAllIntersects(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	seedSmartPlaylistData(t, db)
+
+	// Queen has two tracks; Beyoncé has one; no track is by both.
+	rules := []Rule{
+		{Field: "artist", Operator: "is", Value: "Queen"},
+		{Field: "artist", Operator: "is", Value: "Beyoncé"},
+	}
+
+	all, err := Evaluate(db, RuleSet{Rules: rules, Match: MatchAll})
+	if err != nil {
+		t.Fatalf("Evaluate(all): %v", err)
+	}
+
+	if len(all) != 0 {
+		t.Errorf("match=all returned %d tracks, want 0", len(all))
+	}
+
+	either, err := Evaluate(db, RuleSet{Rules: rules, Match: MatchAny})
+	if err != nil {
+		t.Fatalf("Evaluate(any): %v", err)
+	}
+
+	if len(either) != 3 {
+		t.Fatalf("match=any returned %d tracks, want 3", len(either))
+	}
+
+	for _, tr := range either {
+		if tr.ArtistName != "Queen" && tr.ArtistName != "Beyoncé" {
+			t.Errorf(
+				"track %q has artist %q, want Queen or Beyoncé",
+				tr.TrackName, tr.ArtistName,
+			)
+		}
+	}
+}
+
+// An empty match is what every playlist saved before the field existed
+// carries, and it has to keep meaning AND all the way through Evaluate
+// — a stored playlist silently widening on upgrade is the only real
+// risk in adding this.
+func TestEvaluate_EmptyMatchStillIntersects(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	seedSmartPlaylistData(t, db)
+
+	tracks, err := Evaluate(db, RuleSet{
+		Rules: []Rule{
+			{Field: "artist", Operator: "is", Value: "Queen"},
+			{Field: "year", Operator: "greater_than", Value: "1979"},
+		},
+	})
+	if err != nil {
+		t.Fatalf("Evaluate: %v", err)
+	}
+
+	// Only "Another One Bites the Dust" (Queen, 1980) satisfies both.
+	if len(tracks) != 1 {
+		t.Fatalf("got %d tracks, want 1", len(tracks))
+	}
+
+	if want := "Another One Bites the Dust"; tracks[0].TrackName != want {
+		t.Errorf("got %q, want %q", tracks[0].TrackName, want)
+	}
+}
+
 // TestEvaluate_ArtworkEnrichment verifies the presentation-only
 // cover-art and MusicBrainz-ID fields are attached to matched tracks
 // by the batched fetchArtwork pass (they are no longer part of the
@@ -1340,7 +1519,7 @@ func TestSQLInjection_FieldName(t *testing.T) {
 			Field:    "title; DROP TABLE playlists",
 			Operator: "is", Value: "x",
 		},
-	})
+	}, MatchAll)
 	if err == nil {
 		t.Fatal(
 			"expected error for injected field name, got nil",

backend/system/userdata.go

@@ -52,6 +52,75 @@ func UseHomeOverride(base string) {
 	_ = os.Setenv(envHomeOverride, base)
 }
 
+// envTempDir is the variable Go's os.TempDir() reads, and through it
+// every library in the process that asks for a temporary file.
+const envTempDir = "TMPDIR"
+
+// tempDirName is the subdirectory of the app's own storage that
+// becomes that answer.
+const tempDirName = "tmp"
+
+// UseTempDir gives the process a temporary directory that exists.
+//
+// **Android has no /tmp and hands an app no TMPDIR**, and Go's
+// os.TempDir() falls back to "/tmp" when the variable is unset -- so
+// every library in the process that wants scratch space is handed a
+// path that has never existed. SQLite is the one that noticed: an
+// INSERT ... SELECT large enough to spill returned
+// SQLITE_IOERR_GETTEMPPATH (disk I/O error 6410), which is how the
+// champion search index came to fail its rebuild on every launch while
+// the app otherwise looked healthy (#190).
+//
+// It is the *class* that is fixed here rather than that statement.
+// Anything that spills fails the same way on that platform -- large
+// sorts, large joins, VACUUM -- so the repair belongs at the process's
+// one answer to the question rather than at each caller. The
+// alternative considered was PRAGMA temp_store = MEMORY, which is
+// cheaper and more local and is a promise that every future spill fits
+// in RAM on a phone; the catalog is the largest thing in this app and
+// that is not a promise worth making silently.
+//
+// The rules are UseHomeOverride's, for the same reasons. **An empty
+// base is a no-op**, because that is what
+// application.Mobile.StoragePath() returns on desktop -- so this needs
+// no build tag and changes nothing off mobile, where /tmp is real. And
+// **an explicit TMPDIR wins**, so anyone who set one deliberately gets
+// what they asked for; nothing sets it on the platform this exists for.
+//
+// It returns its error rather than swallowing it because a temp
+// directory that could not be created is the same silent failure one
+// step earlier, and since #160 a log line on that platform is
+// something a person can actually read.
+func UseTempDir(base string) error {
+	if base == "" || os.Getenv(envTempDir) != "" {
+		return nil
+	}
+
+	dir := filepath.Join(base, tempDirName)
+
+	if err := os.MkdirAll(dir, os.ModePerm); err != nil {
+		return fmt.Errorf("could not make the temp directory %s: %w", dir, err)
+	}
+
+	// Writability is checked rather than assumed: the whole failure
+	// this repairs is a directory that is named and cannot be used, and
+	// MkdirAll on an existing unwritable directory succeeds.
+	probe, err := os.CreateTemp(dir, "probe")
+	if err != nil {
+		return fmt.Errorf("temp directory %s is not writable: %w", dir, err)
+	}
+
+	name := probe.Name()
+	_ = probe.Close()
+	_ = os.Remove(name)
+
+	if err := os.Setenv(envTempDir, dir); err != nil {
+		return fmt.Errorf("could not set %s: %w", envTempDir, err)
+	}
+
+	return nil
+}
+
 // getUserDirPath returns and creates the path for a user directory.
 func getUserDirPath(dt dirType) (string, error) {
 	path, err := resolveUserDirPath(dt)

backend/system/userdata_test.go

@@ -87,3 +87,116 @@ func TestUseHomeOverride(t *testing.T) {
 		})
 	}
 }
+
+// UseTempDir carries UseHomeOverride's two rules for the same reasons,
+// plus one of its own: the directory it names has to be usable.
+//
+// **The only tier that can compile the platform this exists for is a
+// phone**, so everything decidable off one is decided here -- which is
+// androidpayload.go's discipline, and is why the platform call is a
+// parameter rather than something this package reaches for. The
+// device's half is a single measurement: no /tmp, no TMPDIR (#190).
+func TestUseTempDir(t *testing.T) {
+	t.Run("an empty base is a no-op", func(t *testing.T) {
+		// This is the desktop case in full: StoragePath() answers ""
+		// off mobile, where /tmp is real and must be left alone.
+		t.Setenv(envTempDir, "")
+
+		if err := UseTempDir(""); err != nil {
+			t.Fatalf("UseTempDir(\"\") = %v, want nil", err)
+		}
+
+		if got := os.Getenv(envTempDir); got != "" {
+			t.Errorf("%s = %q, want it untouched", envTempDir, got)
+		}
+	})
+
+	t.Run("an explicit TMPDIR wins", func(t *testing.T) {
+		const chosen = "/somewhere/deliberate"
+
+		// The base is taken before TMPDIR moves, because t.TempDir()
+		// reads TMPDIR too -- which is the same fact this function is
+		// about, met from the other side.
+		base := t.TempDir()
+
+		t.Setenv(envTempDir, chosen)
+
+		if err := UseTempDir(base); err != nil {
+			t.Fatalf("UseTempDir = %v, want nil", err)
+		}
+
+		if got := os.Getenv(envTempDir); got != chosen {
+			t.Errorf("%s = %q, want the explicit %q", envTempDir, got, chosen)
+		}
+	})
+
+	t.Run("points at a real directory under the base", func(t *testing.T) {
+		base := t.TempDir()
+
+		t.Setenv(envTempDir, "")
+
+		if err := UseTempDir(base); err != nil {
+			t.Fatalf("UseTempDir = %v, want nil", err)
+		}
+
+		got := os.Getenv(envTempDir)
+
+		want := filepath.Join(base, tempDirName)
+		if got != want {
+			t.Fatalf("%s = %q, want %q", envTempDir, got, want)
+		}
+
+		// The whole failure being repaired is a temp directory that is
+		// named and does not exist, so naming one is not enough.
+		info, err := os.Stat(got)
+		if err != nil {
+			t.Fatalf("the temp directory was named but not created: %v", err)
+		}
+
+		if !info.IsDir() {
+			t.Fatalf("%s is not a directory", got)
+		}
+	})
+
+	t.Run("os.TempDir then answers with it", func(t *testing.T) {
+		// The point of setting the variable at all: this is what every
+		// library in the process reads, SQLite's driver included.
+		base := t.TempDir()
+
+		t.Setenv(envTempDir, "")
+
+		if err := UseTempDir(base); err != nil {
+			t.Fatalf("UseTempDir = %v, want nil", err)
+		}
+
+		if got := os.TempDir(); got != filepath.Join(base, tempDirName) {
+			t.Errorf("os.TempDir() = %q, want the directory we made", got)
+		}
+	})
+
+	t.Run("an unwritable directory is an error, not a silent success", func(t *testing.T) {
+		if os.Getuid() == 0 {
+			t.Skip("root can write anywhere, so there is nothing to refuse")
+		}
+
+		base := t.TempDir()
+
+		// MkdirAll on an existing directory succeeds whatever its
+		// mode, so without the write probe this case would set TMPDIR
+		// to a directory nothing can use -- which is the bug again,
+		// one directory over.
+		if err := os.Mkdir(filepath.Join(base, tempDirName), 0o500); err != nil {
+			t.Fatalf("prepare the unwritable directory: %v", err)
+		}
+
+		t.Setenv(envTempDir, "")
+
+		if err := UseTempDir(base); err == nil {
+			t.Fatal("UseTempDir accepted a directory it cannot write to")
+		}
+
+		if got := os.Getenv(envTempDir); got != "" {
+			t.Errorf("%s was set to %q despite the failure", envTempDir, got)
+		}
+	})
+}

backend/tagtotals/tagtotals.go

@@ -0,0 +1,56 @@
+// Package tagtotals derives the totals a tag's "5/12" form declares.
+//
+// It exists because the two writers that know a release's full
+// tracklist -- the autotag apply pass and the download importer --
+// must not import each other or the tag writer, and because getting
+// the denominator wrong is invisible: a total that is too large marks
+// a complete album incomplete forever, and nothing fails.
+package tagtotals
+
+// Position is one track's place in a release.  A zero Disc means the
+// release did not say, which is disc 1.
+type Position struct {
+	Disc  int
+	Track int
+}
+
+// For returns the totals to write on a file sitting on disc `disc`:
+// how many tracks that disc has, and how many discs the release has.
+//
+// The track total is **per disc** and not the release's track count,
+// because that is what the tag form means and what
+// GetAlbumCompleteness sums -- summing a release total once per disc
+// would multiply a two-disc album's expectation by two.
+//
+// Tracks are counted by distinct position rather than by row: a
+// tracklist that lists a position twice is a defect in the source, and
+// counting it twice would put an album permanently out of reach of its
+// own total.
+func For(all []Position, disc int) (tracks, discs int) {
+	disc = normaliseDisc(disc)
+
+	seenTracks := make(map[int]struct{}, len(all))
+	seenDiscs := make(map[int]struct{}, 1)
+
+	for _, p := range all {
+		d := normaliseDisc(p.Disc)
+		seenDiscs[d] = struct{}{}
+
+		if d != disc || p.Track <= 0 {
+			continue
+		}
+
+		seenTracks[p.Track] = struct{}{}
+	}
+
+	return len(seenTracks), len(seenDiscs)
+}
+
+// normaliseDisc treats an undeclared disc as disc 1.
+func normaliseDisc(d int) int {
+	if d <= 0 {
+		return 1
+	}
+
+	return d
+}

backend/tagtotals/tagtotals_test.go

@@ -0,0 +1,92 @@
+package tagtotals_test
+
+import (
+	"testing"
+
+	"yellowjacket/backend/tagtotals"
+)
+
+func TestFor(t *testing.T) {
+	t.Parallel()
+
+	singleDisc := []tagtotals.Position{
+		{Disc: 0, Track: 1}, {Disc: 0, Track: 2}, {Disc: 0, Track: 3},
+	}
+
+	twoDiscs := []tagtotals.Position{
+		{Disc: 1, Track: 1},
+		{Disc: 1, Track: 2},
+		{Disc: 2, Track: 1},
+		{Disc: 2, Track: 2},
+		{Disc: 2, Track: 3},
+	}
+
+	tests := []struct {
+		name       string
+		all        []tagtotals.Position
+		disc       int
+		wantTracks int
+		wantDiscs  int
+	}{
+		{
+			name: "a single-disc release totals its own tracks",
+			all:  singleDisc, disc: 0, wantTracks: 3, wantDiscs: 1,
+		},
+		{
+			// An undeclared disc is disc 1, on both sides of the
+			// question -- a file tagged "disc 1" and a tracklist that
+			// declares no disc describe the same disc.
+			name: "an undeclared disc is disc 1",
+			all:  singleDisc, disc: 1, wantTracks: 3, wantDiscs: 1,
+		},
+		{
+			// The whole point: 5 here would be the release's track
+			// count, which summed once per disc claims a ten-track
+			// expectation for a five-track album.
+			name: "a multi-disc release totals the file's own disc",
+			all:  twoDiscs, disc: 2, wantTracks: 3, wantDiscs: 2,
+		},
+		{
+			name: "the other disc gets its own total",
+			all:  twoDiscs, disc: 1, wantTracks: 2, wantDiscs: 2,
+		},
+		{
+			// A disc the tracklist does not mention cannot be totalled,
+			// and 0 is how the caller is told to write nothing.
+			name: "a disc with no tracks totals nothing",
+			all:  twoDiscs, disc: 3, wantTracks: 0, wantDiscs: 2,
+		},
+		{
+			name: "an empty tracklist totals nothing",
+			all:  nil, disc: 1, wantTracks: 0, wantDiscs: 0,
+		},
+		{
+			// A source that lists a position twice would otherwise put
+			// the album permanently one track short of its own total.
+			name: "a repeated position counts once",
+			all: []tagtotals.Position{
+				{Disc: 1, Track: 1}, {Disc: 1, Track: 1}, {Disc: 1, Track: 2},
+			},
+			disc: 1, wantTracks: 2, wantDiscs: 1,
+		},
+		{
+			name: "a track with no position is not counted",
+			all: []tagtotals.Position{
+				{Disc: 1, Track: 0}, {Disc: 1, Track: 1},
+			},
+			disc: 1, wantTracks: 1, wantDiscs: 1,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			tracks, discs := tagtotals.For(tc.all, tc.disc)
+			if tracks != tc.wantTracks || discs != tc.wantDiscs {
+				t.Errorf("For(%v, %d) = (%d, %d), want (%d, %d)",
+					tc.all, tc.disc, tracks, discs, tc.wantTracks, tc.wantDiscs)
+			}
+		})
+	}
+}

backend/tagwriter/dbsync.go

@@ -183,6 +183,15 @@ func syncDatabase(
 		discNum = toNullInt64(v)
 	}
 
+	// The completeness evidence.  Without this the row keeps whatever
+	// the last scan read while the file on disk now declares a total,
+	// so the album stays "unknown" until a full rescan -- which is the
+	// state the report describes.
+	totalTracks := old.TotalTracks
+	if v, ok := asInt(params.changes[FieldTotalTracks]); ok {
+		totalTracks = toNullInt64(v)
+	}
+
 	composer := old.Composer
 	if v, ok := params.changes[FieldComposer].(string); ok {
 		composer = v
@@ -207,7 +216,7 @@ func syncDatabase(
 		AlbumID:            albumID,
 		TrackNumber:        trackNum,
 		DiscNumber:         discNum,
-		TotalTracks:        old.TotalTracks,
+		TotalTracks:        totalTracks,
 		Year:               year,
 		Composer:           composer,
 		Comment:            old.Comment,

backend/tagwriter/flac.go

@@ -101,6 +101,11 @@ func applyFlacTextChanges(cmt *flacvorbis.MetaDataBlockVorbisComment, changes Ta
 		{FieldYear, flacvorbis.FIELD_DATE, true},
 		{FieldTrackNumber, flacvorbis.FIELD_TRACKNUMBER, true},
 		{FieldDiscNumber, "DISCNUMBER", true},
+		// TRACKTOTAL/DISCTOTAL and no other spelling: dhowden/tag's
+		// Vorbis reader looks at exactly these two keys, so TOTALTRACKS
+		// or a "1/12" inside TRACKNUMBER reads back as no total at all.
+		{FieldTotalTracks, "TRACKTOTAL", true},
+		{FieldTotalDiscs, "DISCTOTAL", true},
 		{FieldComposer, "COMPOSER", false},
 	}
 

backend/tagwriter/mp3.go

@@ -6,6 +6,7 @@ import (
 	"log/slog"
 	"os"
 	"strconv"
+	"strings"
 
 	id3v2 "github.com/bogem/id3v2/v2"
 
@@ -66,17 +67,10 @@ func applyTextChanges(tag *id3v2.Tag, changes TagChanges) {
 		tag.SetYear(strconv.Itoa(v))
 	}
 
-	if v, ok := asInt(changes[FieldTrackNumber]); ok {
-		trckID := tag.CommonID("Track number/Position in set")
-		tag.DeleteFrames(trckID)
-		tag.AddTextFrame(trckID, id3v2.EncodingUTF8, strconv.Itoa(v))
-	}
-
-	if v, ok := asInt(changes[FieldDiscNumber]); ok {
-		tposID := tag.CommonID("Part of a set")
-		tag.DeleteFrames(tposID)
-		tag.AddTextFrame(tposID, id3v2.EncodingUTF8, strconv.Itoa(v))
-	}
+	applyPositionFrame(tag, "Track number/Position in set", changes,
+		FieldTrackNumber, FieldTotalTracks)
+	applyPositionFrame(tag, "Part of a set", changes,
+		FieldDiscNumber, FieldTotalDiscs)
 
 	if v, ok := changes[FieldComposer].(string); ok {
 		tag.DeleteFrames("TCOM")
@@ -90,6 +84,64 @@ func applyTextChanges(tag *id3v2.Tag, changes TagChanges) {
 	}
 }
 
+// applyPositionFrame writes an ID3v2 position frame (TRCK or TPOS) in
+// the "n/N" form the readers parse.
+//
+// The number and the total are separate diff entries and either may be
+// absent, so the frame's *existing* value is the base: writing a total
+// alone must not discard the number that is already there, and writing
+// a number alone must not discard a total the file already declared.
+// A total with no number at all is not written, since "/12" says
+// nothing a reader can use.
+func applyPositionFrame(
+	tag *id3v2.Tag, description string, changes TagChanges, numKey, totalKey string,
+) {
+	_, hasNum := changes[numKey]
+	_, hasTotal := changes[totalKey]
+
+	if !hasNum && !hasTotal {
+		return
+	}
+
+	frameID := tag.CommonID(description)
+
+	num, total := parseXofN(
+		strings.TrimRight(tag.GetTextFrame(frameID).Text, "\x00 \t\n\r"),
+	)
+
+	if v, ok := asInt(changes[numKey]); ok {
+		num = v
+	}
+
+	if v, ok := asInt(changes[totalKey]); ok {
+		total = v
+	}
+
+	if num <= 0 {
+		return
+	}
+
+	value := strconv.Itoa(num)
+	if total > 0 {
+		value += "/" + strconv.Itoa(total)
+	}
+
+	tag.DeleteFrames(frameID)
+	tag.AddTextFrame(frameID, id3v2.EncodingUTF8, value)
+}
+
+// parseXofN splits an ID3v2 "n/N" position value.  A bare "n" yields a
+// zero total, and anything unparseable yields zeros — the same reading
+// dhowden/tag gives the frame.
+func parseXofN(s string) (int, int) {
+	numText, totalText, _ := strings.Cut(s, "/")
+
+	num, _ := strconv.Atoi(strings.TrimSpace(numText))
+	total, _ := strconv.Atoi(strings.TrimSpace(totalText))
+
+	return num, total
+}
+
 // applyCoverArtChanges handles the FieldCoverArt entry in the diff map.
 //
 //   - []byte with len > 0: embed the given image as front cover.

backend/tagwriter/ogg_vorbis.go

@@ -166,6 +166,8 @@ var oggFieldMappings = []struct { //nolint:gochecknoglobals // field mapping tab
 	{FieldYear, "DATE", true},
 	{FieldTrackNumber, "TRACKNUMBER", true},
 	{FieldDiscNumber, "DISCNUMBER", true},
+	{FieldTotalTracks, "TRACKTOTAL", true},
+	{FieldTotalDiscs, "DISCTOTAL", true},
 	{FieldComposer, "COMPOSER", false},
 }
 

backend/tagwriter/pipeline_test.go

@@ -333,3 +333,31 @@ func TestWriteTrackTags_DBSync(t *testing.T) {
 		t.Error("expected FTS5 result for 'New Title'")
 	}
 }
+
+// The row is what the album page reads, and it is only refreshed by a
+// scan.  Leaving total_tracks at whatever the last scan saw means an
+// album autotagged just now stays "unknown" -- a plain tick on an album
+// the user holds two tracks of -- until a full rescan happens to run.
+func TestWriteTrackTags_PersistsTheTotal(t *testing.T) {
+	db := database.NewTestDB(t)
+	dir := t.TempDir()
+	trackID := seedTestTrack(t, db, createPipelineTestMP3(t, dir))
+
+	tw := NewTagWriter(testLogger(), db, &mockPlayer{}, &mockPipelineLocker{})
+
+	if err := tw.WriteTrackTags(trackID, TagChanges{
+		FieldTrackNumber: 2,
+		FieldTotalTracks: 10,
+	}); err != nil {
+		t.Fatalf("WriteTrackTags: %v", err)
+	}
+
+	af, err := db.Queries.GetAudioFile(context.Background(), trackID)
+	if err != nil {
+		t.Fatalf("get audio file: %v", err)
+	}
+
+	if !af.TotalTracks.Valid || af.TotalTracks.Int64 != 10 {
+		t.Errorf("total_tracks: got %v, want 10", af.TotalTracks)
+	}
+}

backend/tagwriter/tagwriter.go

@@ -26,6 +26,15 @@ const (
 	FieldDiscNumber  = "disc_number"
 	FieldComposer    = "composer"
 	FieldCoverArt    = "cover_art" // []byte for set, nil for clear
+
+	// FieldTotalTracks is how many tracks are on *this file's disc*, not
+	// in the whole release.  That is what the "5/12" form declares and
+	// what GetAlbumCompleteness sums per disc; a release total written
+	// here would multiply the expectation by the number of discs.
+	FieldTotalTracks = "total_tracks"
+
+	// FieldTotalDiscs is how many discs the release has.
+	FieldTotalDiscs = "total_discs"
 )
 
 // AudioFormat represents a supported audio file format.

backend/tagwriter/totals_test.go

@@ -0,0 +1,199 @@
+package tagwriter
+
+import (
+	"path/filepath"
+	"testing"
+
+	"yellowjacket/backend/metadata"
+)
+
+// The totals are the evidence GetAlbumCompleteness reads, and every way
+// of getting them wrong is silent: a tag written under a name the
+// reader does not look at reads back as no total at all, which is
+// indistinguishable from never having written one.  So these assert the
+// round trip through the *reader the scan uses*, not the bytes.
+//
+// WAV is the exception and it is not this change's: dhowden/tag has no
+// RIFF reader at all, so metadata.ExtractTags cannot see a WAV's ID3
+// chunk -- which is why every other test here reads that chunk itself.
+func TestWriteTotals_RoundTripsInEveryFormat(t *testing.T) {
+	t.Parallel()
+
+	changes := TagChanges{
+		FieldTitle:       "Some Song",
+		FieldTrackNumber: 2,
+		FieldTotalTracks: 10,
+		FieldDiscNumber:  1,
+		FieldTotalDiscs:  2,
+	}
+
+	viaScanner := func(t *testing.T, path string) *metadata.TrackMetadata {
+		t.Helper()
+
+		meta, err := metadata.ExtractTags(path)
+		if err != nil {
+			t.Fatalf("ExtractTags: %v", err)
+		}
+
+		return meta
+	}
+
+	tests := []struct {
+		name  string
+		write func(t *testing.T, dir string) string
+		read  func(t *testing.T, path string) *metadata.TrackMetadata
+	}{
+		{
+			name: "mp3",
+			read: viaScanner,
+			write: func(t *testing.T, dir string) string {
+				t.Helper()
+
+				path := createTestMP3(t, dir, "totals.mp3", nil)
+				if err := writeMp3Tags(testLogger(), path, changes); err != nil {
+					t.Fatalf("writeMp3Tags: %v", err)
+				}
+
+				return path
+			},
+		},
+		{
+			name: "flac",
+			read: viaScanner,
+			write: func(t *testing.T, dir string) string {
+				t.Helper()
+
+				path := filepath.Join(dir, "totals.flac")
+				makeMinimalFLAC(t, path)
+
+				if err := writeFlacTags(testLogger(), path, changes); err != nil {
+					t.Fatalf("writeFlacTags: %v", err)
+				}
+
+				return path
+			},
+		},
+		{
+			name: "ogg",
+			read: viaScanner,
+			write: func(t *testing.T, dir string) string {
+				t.Helper()
+
+				path := filepath.Join(dir, "totals.ogg")
+				createTestOGG(t, path)
+
+				if err := writeOggTags(testLogger(), path, changes); err != nil {
+					t.Fatalf("writeOggTags: %v", err)
+				}
+
+				return path
+			},
+		},
+		{
+			name: "wav",
+			read: readWavID3Tags,
+			write: func(t *testing.T, dir string) string {
+				t.Helper()
+
+				path := createTestWAV(t, dir, "totals.wav", nil)
+
+				if err := writeWavTags(testLogger(), path, changes); err != nil {
+					t.Fatalf("writeWavTags: %v", err)
+				}
+
+				return path
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			meta := tc.read(t, tc.write(t, t.TempDir()))
+
+			assertIntField(t, "TrackNumber", meta.TrackNumber, 2)
+			assertIntField(t, "TotalTracks", meta.TotalTracks, 10)
+			assertIntField(t, "DiscNumber", meta.DiscNumber, 1)
+			assertIntField(t, "TotalDiscs", meta.TotalDiscs, 2)
+		})
+	}
+}
+
+// A number and a total are separate diff entries, so writing one must
+// not discard the other.  For ID3v2 they share a single "n/N" frame,
+// which is the only place this can go wrong -- and it goes wrong by
+// silently zeroing a total the file already declared.
+func TestWriteMp3Totals_PartialUpdateKeepsTheOtherHalf(t *testing.T) {
+	t.Parallel()
+
+	t.Run("writing the number keeps the total", func(t *testing.T) {
+		t.Parallel()
+
+		dir := t.TempDir()
+		path := createTestMP3(t, dir, "seeded.mp3", TagChanges{
+			FieldTrackNumber: 2,
+			FieldTotalTracks: 10,
+		})
+
+		if err := writeMp3Tags(testLogger(), path, TagChanges{
+			FieldTrackNumber: 4,
+		}); err != nil {
+			t.Fatalf("writeMp3Tags: %v", err)
+		}
+
+		meta, err := metadata.ExtractTags(path)
+		if err != nil {
+			t.Fatalf("ExtractTags: %v", err)
+		}
+
+		assertIntField(t, "TrackNumber", meta.TrackNumber, 4)
+		assertIntField(t, "TotalTracks", meta.TotalTracks, 10)
+	})
+
+	t.Run("writing the total keeps the number", func(t *testing.T) {
+		t.Parallel()
+
+		dir := t.TempDir()
+		path := createTestMP3(t, dir, "seeded.mp3", TagChanges{
+			FieldTrackNumber: 7,
+		})
+
+		if err := writeMp3Tags(testLogger(), path, TagChanges{
+			FieldTotalTracks: 12,
+		}); err != nil {
+			t.Fatalf("writeMp3Tags: %v", err)
+		}
+
+		meta, err := metadata.ExtractTags(path)
+		if err != nil {
+			t.Fatalf("ExtractTags: %v", err)
+		}
+
+		assertIntField(t, "TrackNumber", meta.TrackNumber, 7)
+		assertIntField(t, "TotalTracks", meta.TotalTracks, 12)
+	})
+
+	// "/12" says nothing a reader can use, and dhowden/tag reads it as
+	// track 0 -- which the scan would store as a real track number.
+	t.Run("a total with no number writes nothing", func(t *testing.T) {
+		t.Parallel()
+
+		dir := t.TempDir()
+		path := createTestMP3(t, dir, "bare.mp3", nil)
+
+		if err := writeMp3Tags(testLogger(), path, TagChanges{
+			FieldTotalTracks: 12,
+		}); err != nil {
+			t.Fatalf("writeMp3Tags: %v", err)
+		}
+
+		meta, err := metadata.ExtractTags(path)
+		if err != nil {
+			t.Fatalf("ExtractTags: %v", err)
+		}
+
+		assertIntField(t, "TrackNumber", meta.TrackNumber, 0)
+		assertIntField(t, "TotalTracks", meta.TotalTracks, 0)
+	})
+}

backend/tagwriter/wav_test.go

@@ -522,19 +522,20 @@ func readWavID3Tags(
 		}
 	}
 
-	// Track number (TRCK).
+	// Track number and total (TRCK), disc number and total (TPOS).
+	// Both carry the "n/N" form, so they are read the way a reader
+	// reads them rather than with Atoi -- which sees "2/10" as 0.
 	trckID := parsed.CommonID("Track number/Position in set")
 	if frames := parsed.GetFrames(trckID); len(frames) > 0 {
 		if tf, ok := frames[0].(id3v2.TextFrame); ok {
-			meta.TrackNumber = atoiSafe(tf.Text)
+			meta.TrackNumber, meta.TotalTracks = parseXofN(tf.Text)
 		}
 	}
 
-	// Disc number (TPOS).
 	tposID := parsed.CommonID("Part of a set")
 	if frames := parsed.GetFrames(tposID); len(frames) > 0 {
 		if tf, ok := frames[0].(id3v2.TextFrame); ok {
-			meta.DiscNumber = atoiSafe(tf.Text)
+			meta.DiscNumber, meta.TotalDiscs = parseXofN(tf.Text)
 		}
 	}
 

build/android/Taskfile.yml

@@ -4,18 +4,28 @@ includes:
   common: ../Taskfile.yml
 
 vars:
-  # The *installed* package name, which every adb-driven task below uses
-  # to uninstall, launch and filter. It must agree with `applicationId`
-  # in app/build.gradle, and nothing enforces that.
+  # APP_ID is an *assertion*, not a setting, and it has no default.
   #
-  # ANDROID.md says to set this in build/config.yml. That does not work
-  # in beta.8, checked both ways: `wails3 task` builds its var set from
-  # CLI KEY=VALUE arguments and the Taskfile tree only -- nothing reads
-  # config.yml -- and even when set it feeds only these adb commands,
-  # never Gradle. So the identity is declared twice, here and in
-  # build.gradle, and a change to one alone means the official run and
-  # deploy tasks address a package that is not installed.
-  APP_ID: '{{.APP_ID | default "app.yellowjacket"}}'
+  # It used to be the id every adb-driven task below uninstalled,
+  # launched and filtered, defaulting to "app.yellowjacket". It could
+  # never have been a setting: `wails3 task` builds its var set from CLI
+  # KEY=VALUE arguments and the Taskfile tree only -- nothing reads
+  # build/config.yml, contrary to ANDROID.md, checked with --dry -- and
+  # even when set it fed only the adb commands, never Gradle. So the
+  # identity was declared twice, here and as `applicationId` in
+  # app/build.gradle, with nothing enforcing that they agree.
+  #
+  # They did not agree. The debug buildType carries
+  # `applicationIdSuffix ".dev"`, so the tasks that assemble a debug APK
+  # addressed the *release* id -- on a device, the user's installed app
+  # and their library (#159).
+  #
+  # The id is now read back from the built APK by scripts/android-
+  # pkgid.sh, so the thing installed and the thing launched agree by
+  # construction. Passing APP_ID= says "this build had better declare
+  # that id", and the deploy refuses before touching anything if it does
+  # not -- which is the check that would have caught #159 statically.
+  APP_ID: '{{.APP_ID | default ""}}'
   MIN_SDK: '21'
   TARGET_SDK: '35'
   # The emulator runs the host architecture; physical devices are arm64
@@ -372,9 +382,7 @@ tasks:
           ARCH: '{{.ARCH | default .HOST_ARCH}}'
     cmds:
       - task: ensure-emulator
-      - '"{{.ADB}}" uninstall {{.APP_ID}} 2>/dev/null || true'
-      - '"{{.ADB}}" install "{{.BIN_DIR}}/{{.APP_NAME}}.apk"'
-      - '"{{.ADB}}" shell am start -n {{.APP_ID}}/com.wails.app.MainActivity'
+      - './scripts/android-deploy.sh --apk "{{.BIN_DIR}}/{{.APP_NAME}}.apk" --target emulator{{if .APP_ID}} --expect "{{.APP_ID}}"{{end}}'
 
   run:
     summary: Build, install and launch a debug build in the Android Emulator
@@ -383,9 +391,7 @@ tasks:
       - task: build
     cmds:
       - task: assemble:apk
-      - '"{{.ADB}}" uninstall {{.APP_ID}} 2>/dev/null || true'
-      - '"{{.ADB}}" install "{{.BIN_DIR}}/{{.APP_NAME}}.apk"'
-      - '"{{.ADB}}" shell am start -n {{.APP_ID}}/com.wails.app.MainActivity'
+      - './scripts/android-deploy.sh --apk "{{.BIN_DIR}}/{{.APP_NAME}}.apk" --target emulator{{if .APP_ID}} --expect "{{.APP_ID}}"{{end}}'
 
   device:list:
     summary: Lists connected Android devices and emulators (serials)
@@ -400,25 +406,7 @@ tasks:
           ARCH: arm64
     cmds:
       - task: assemble:apk
-      - |
-        DEVICE='{{.DEVICE_ID | default ""}}'
-        if [ -z "$DEVICE" ]; then
-          DEVICE="${DEVICE_ID:-}"
-        fi
-        if [ -z "$DEVICE" ]; then
-          DEVICE=$("{{.ADB}}" devices | awk 'NR > 1 && $2 == "device" && $1 !~ /^emulator-/ { print $1; exit }')
-        fi
-        if [ -z "$DEVICE" ]; then
-          echo "Error: no connected physical Android device found."
-          echo "Pass DEVICE_ID=<serial> to target a device explicitly."
-          echo "Find connected device serials with: {{.ADB}} devices"
-          exit 1
-        fi
-
-        echo "Deploying {{.BIN_DIR}}/{{.APP_NAME}}.apk to device $DEVICE..."
-        "{{.ADB}}" -s "$DEVICE" uninstall {{.APP_ID}} 2>/dev/null || true
-        "{{.ADB}}" -s "$DEVICE" install "{{.BIN_DIR}}/{{.APP_NAME}}.apk"
-        "{{.ADB}}" -s "$DEVICE" shell am start -n {{.APP_ID}}/com.wails.app.MainActivity
+      - './scripts/android-deploy.sh --apk "{{.BIN_DIR}}/{{.APP_NAME}}.apk" --target device{{if .DEVICE_ID}} --serial "{{.DEVICE_ID}}"{{end}}{{if .APP_ID}} --expect "{{.APP_ID}}"{{end}}'
     preconditions:
       - sh: '[ -x "{{.ADB}}" ] || command -v adb'
         msg: "adb not found. Install the Android SDK platform-tools (or set ANDROID_HOME)"
@@ -430,25 +418,7 @@ tasks:
         vars:
           ARCH: arm64
     cmds:
-      - |
-        DEVICE='{{.DEVICE_ID | default ""}}'
-        if [ -z "$DEVICE" ]; then
-          DEVICE="${DEVICE_ID:-}"
-        fi
-        if [ -z "$DEVICE" ]; then
-          DEVICE=$("{{.ADB}}" devices | awk 'NR > 1 && $2 == "device" && $1 !~ /^emulator-/ { print $1; exit }')
-        fi
-        if [ -z "$DEVICE" ]; then
-          echo "Error: no connected physical Android device found."
-          echo "Pass DEVICE_ID=<serial> to target a device explicitly."
-          echo "Find connected device serials with: {{.ADB}} devices"
-          exit 1
-        fi
-
-        echo "Deploying {{.BIN_DIR}}/{{.APP_NAME}}.apk to device $DEVICE..."
-        "{{.ADB}}" -s "$DEVICE" uninstall {{.APP_ID}} 2>/dev/null || true
-        "{{.ADB}}" -s "$DEVICE" install "{{.BIN_DIR}}/{{.APP_NAME}}.apk"
-        "{{.ADB}}" -s "$DEVICE" shell am start -n {{.APP_ID}}/com.wails.app.MainActivity
+      - './scripts/android-deploy.sh --apk "{{.BIN_DIR}}/{{.APP_NAME}}.apk" --target device{{if .DEVICE_ID}} --serial "{{.DEVICE_ID}}"{{end}}{{if .APP_ID}} --expect "{{.APP_ID}}"{{end}}'
     preconditions:
       - sh: '[ -x "{{.ADB}}" ] || command -v adb'
         msg: "adb not found. Install the Android SDK platform-tools (or set ANDROID_HOME)"

build/android/app/src/main/java/com/wails/app/MainActivity.java

@@ -891,13 +891,41 @@ public class MainActivity extends AppCompatActivity {
         }
     }
 
+    /**
+     * The activity going away is not the app shutting down.
+     *
+     * <p>The scaffold called {@code bridge.shutdown()} here, which is
+     * the natural reading of onDestroy and is wrong for this app twice
+     * over. Android destroys and recreates an activity for a
+     * configuration change the manifest does not declare, under memory
+     * pressure, and on every background if the user has "Don't keep
+     * activities" on -- all **without restarting the process**. And
+     * when the user really does leave, this app's reason for existing
+     * in the background is that a song is playing, which is what the
+     * {@code mediaPlayback} foreground service is holding the process
+     * alive for. Either way, tearing the Go side down here would stop
+     * the music.
+     *
+     * <p>It was harmless only by accident: {@code nativeShutdown} calls
+     * {@code App.Quit()}, whose Android {@code destroy()} is an empty
+     * method, and {@code Run()}'s deferred {@code shutdownServices()}
+     * can never fire because Android's {@code platformRun} is
+     * {@code select{}} and does not return. So no {@code
+     * ServiceShutdown} has ever run on Android, and removing this call
+     * changes nothing today -- it stops the day someone implements
+     * {@code destroy()} from silently killing playback on a rotation.
+     *
+     * <p>There is no callback for "the process is going away"; Android
+     * simply kills it. Durability on this platform is the persist
+     * writers, which submit on every mutation rather than at exit.
+     *
+     * <p>See #52, and CLAUDE.md, "An activity is a view onto the
+     * process".
+     */
     @Override
     protected void onDestroy() {
         super.onDestroy();
         unregisterSystemEventReceivers();
-        if (bridge != null) {
-            bridge.shutdown();
-        }
         if (webView != null) {
             webView.destroy();
         }

build/android/app/src/main/java/com/wails/app/WailsBridge.java

@@ -129,7 +129,24 @@ public class WailsBridge {
     }
 
     /**
-     * Initialize the native Go library
+     * Initialize the native Go library.
+     *
+     * <p><b>{@code initialized} is deliberately per-instance, and making
+     * it {@code static} is the trap this comment exists for.</b> A
+     * recreated activity builds a new bridge and calls this again, in a
+     * process where the native library is already loaded and Go's
+     * {@code main()} is already running -- so "initialise once per
+     * process" looks like exactly the right rule. It is not, because
+     * {@code nativeInit} does <i>two</i> things: it runs
+     * {@code go mainFunc()}, and it stores the global JNI reference to
+     * <i>this</i> bridge. Skip it and Go keeps executing JavaScript
+     * against the destroyed activity's WebView: the app opens, renders,
+     * and never receives another backend event.
+     *
+     * <p>So this is called every time, and the half that must not repeat
+     * is latched on the Go side instead, at the top of {@code main()} --
+     * which is also where the damage was ({@code os.Exit(1)}), and the
+     * only place that can see it. See #52.
      */
     public void initialize() {
         if (initialized) {

docs/android-release.md

@@ -7,12 +7,22 @@ which is what lets Obtainium poll a plain URL with no token. It also
 attaches the same file to the Gitea release, which is what a person
 looking at the release page downloads.
 
-**Tags are not pushed by hand any more.** `.gitea/workflows/release.yml`
-reads the Conventional Commits on every merge to `main`, decides the
-version, and pushes the tag this workflow is keyed on — so releasing the
-APK means merging a `fix:` or `feat:` commit, not running `git tag`. The
-`workflow_dispatch` path below remains, for rebuilding a tag that already
-exists.
+**Tags are not pushed by hand any more, but releasing is a decision.**
+`.gitea/workflows/release.yml` reads the Conventional Commits since the
+last tag, decides the version, and pushes the tag this workflow is keyed
+on — so releasing the APK means **running that workflow**, not running
+`git tag`. It has no push trigger: merging a `fix:` or `feat:` used to
+be enough and produced a version per merged PR (issue #115). Run it with
+`dry_run` first to see what the accumulated commits would ship. The
+`workflow_dispatch` path below is a different thing and remains, for
+rebuilding a tag that already exists.
+
+**A prerelease tag is skipped here**, cleanly. This workflow triggers on
+`v*`, which matches `v0.4.0-beta.1`, and it is the one where that would
+hurt most: the APK goes to the credential-free generic registry that
+Obtainium polls, and the `versionCode` maths below splits on dots — it
+would read `1` out of `0-beta` and produce a wrong number rather than a
+failed build.
 
 ## The 1.x installs cannot be upgraded to 0.0.x
 

docs/dev/config-suggestions.md

@@ -1,194 +0,0 @@
-# Config Improvement Suggestions
-
-Remaining suggestions for improving the configuration system in YellowJacket.
-
-## 2. Thread Safety Concerns
-
-The current `Config` struct lacks synchronization:
-- `Load()` and `Save()` can race with concurrent reads
-- `handleConfigUpdate()` in library mutates `l.conf.DirectoryPath` without locks
-
-**Suggestion:** Add a `sync.RWMutex` to protect config access, especially if config is read during scans.
-
-```go
-type Config struct {
-    mu       sync.RWMutex
-    ctx      context.Context
-    logger   *slog.Logger
-    // ...
-}
-
-func (c *Config) Load() error {
-    c.mu.Lock()
-    defer c.mu.Unlock()
-    // ...
-}
-```
-
-## 3. Nil Safety in Validation
-
-In `config.go`, validation only runs if `c.Library != nil`, but `handleConfigPost` dereferences `postedConfig.Library` without checking for nil:
-
-```go
-if postedConfig.Library != nil {
-    c.Library = postedConfig.Library
-    // ...
-}
-```
-
-**Status:** Partially addressed in the event refactor, but consider adding explicit nil checks in `Validate()` as well.
-
-## 4. Inconsistent Error Handling on HTTP Responses
-
-In `httphandler.go:28-31`, `WriteHeader` is called *after* rendering the error template, which won't work as expected (headers must be set before writing body):
-
-```go
-c.formSubmitError(err.Error()).Render(r.Context(), w)
-w.WriteHeader(http.StatusInternalServerError)  // Too late!
-```
-
-**Fix:** Set the status code before rendering:
-
-```go
-w.WriteHeader(http.StatusInternalServerError)
-c.formSubmitError(err.Error()).Render(r.Context(), w)
-```
-
-## 5. Make `scanWorkerCount` Configurable
-
-There's a TODO at `library.go:289`:
-```go
-// TODO: make configurable via Config.
-var scanWorkerCount = goruntime.NumCPU()
-```
-
-**Suggestion:** Add this to `library.Config`:
-
-```go
-type Config struct {
-    DirectoryPath Directory `form:"Directory" schema:"directory,required"`
-    ScanWorkers   int       `form:"ScanWorkers" schema:"scan_workers"`
-}
-```
-
-Then in `NewLibrary()` or `Scan()`:
-
-```go
-workers := l.conf.ScanWorkers
-if workers <= 0 {
-    workers = goruntime.NumCPU()
-}
-```
-
-## 6. Consider Config Defaults
-
-Currently if no config exists, an empty one is saved. Consider providing sensible defaults (e.g., common music directories like `~/Music`).
-
-```go
-func (c *Config) setDefaults() {
-    if c.Library == nil {
-        c.Library = &library.Config{}
-    }
-    if c.Library.DirectoryPath == "" {
-        // Try common music directories
-        home, _ := os.UserHomeDir()
-        musicDir := filepath.Join(home, "Music")
-        if info, err := os.Stat(musicDir); err == nil && info.IsDir() {
-            c.Library.DirectoryPath = library.Directory(musicDir)
-        }
-    }
-}
-```
-
-## 7. Config Reload/Watch Capability
-
-The config is only loaded at startup. Consider adding:
-- File watcher for external config changes (using `fsnotify`)
-- Explicit reload method callable from UI
-
-```go
-func (c *Config) Watch() error {
-    watcher, err := fsnotify.NewWatcher()
-    if err != nil {
-        return err
-    }
-    
-    go func() {
-        for event := range watcher.Events {
-            if event.Op&fsnotify.Write == fsnotify.Write {
-                c.Load()
-                // Emit event for listeners
-            }
-        }
-    }()
-    
-    return watcher.Add(c.filePath)
-}
-```
-
-## 8. Validation Should Return Structured Errors
-
-Currently validation returns combined errors. Consider returning a structured validation result that the UI can map to specific fields for better user feedback.
-
-```go
-type ValidationError struct {
-    Field   string
-    Message string
-}
-
-type ValidationResult struct {
-    Valid  bool
-    Errors []ValidationError
-}
-
-func (c *Config) ValidateStructured() ValidationResult {
-    var result ValidationResult
-    result.Valid = true
-    
-    if c.Library != nil {
-        if err := c.Library.Validate(); err != nil {
-            result.Valid = false
-            result.Errors = append(result.Errors, ValidationError{
-                Field:   "Library.DirectoryPath",
-                Message: err.Error(),
-            })
-        }
-    }
-    
-    return result
-}
-```
-
-## 9. Use Standard Library for Config Paths
-
-The path construction in `system/userdata.go` doesn't respect `$XDG_CONFIG_HOME` on Linux or use the standard Go `os.UserConfigDir()`.
-
-**Current implementation:**
-```go
-case "linux":
-    return fmt.Sprintf("/home/%s/%s/yellowjacket", username, unixSubdirs[dt]), nil
-```
-
-**Suggested improvement:**
-```go
-func GetUserConfigDirPath() (string, error) {
-    baseDir, err := os.UserConfigDir()  // Respects XDG_CONFIG_HOME
-    if err != nil {
-        return "", fmt.Errorf("could not get user config directory: %w", err)
-    }
-    
-    path := filepath.Join(baseDir, "yellowjacket")
-    
-    if err := os.MkdirAll(path, 0o755); err != nil {
-        return "", fmt.Errorf("could not create config directory: %w", err)
-    }
-    
-    return path, nil
-}
-```
-
-This approach:
-- Respects `$XDG_CONFIG_HOME` on Linux
-- Uses proper macOS paths (`~/Library/Application Support`)
-- Uses `%AppData%` on Windows
-- Is more portable and follows platform conventions

docs/dev/overview.md

@@ -1,53 +0,0 @@
-# Development Overview
-
-YellowJacket is a moderately complex application. This document gives an overview of how development of it works.
-
-## Logical Breakdown
-
-YellowJacket can be thought about in a heirarchy of logical modules and components. The borders of these logical sections are mostly represented in the code and directory structure as well.
-
-- Frontend
-  - UI Components (see [Lit](###lit-web-components))
-- Backend
-  - App
-    - Asset Handler
-    - Logging
-    - System
-  - Player
-  - Library
-  - Config
-  - Database
-    - Queries (see [sqlc](###sqlc))
-
-## Dependencies
-
-YellowJacket uses many tools and libraries to provide its functionality. 
-This section lists each of these dependencies and explains how they are used.
-
-### [Wails](https://wails.io)
-
-Used to create desktop apps with Go and web technologies.
-
-### [SQLite](https://github.com/mattn/go-sqlite3?tab=readme-ov-file#go-sqlite3)
-
-Used for local database.
-
-### [sqlc](https://sqlc.dev/)
-
-Used to generate Go code from SQL.
-
-### [Templ](https://templ.guide/)
-
-Used to generate HTML templates with Go code.
-
-### [Beep](https://github.com/gopxl/beep?tab=readme-ov-file#beep)
-
-Used for audio playback.
-
-### [Lit Web Components](https://lit.dev/)
-
-Used for dynamic/reactive frontend components.
-
-### [HTMX](https://htmx.org/)
-
-Used for requesting HTML fragments from the backend and rendering them on the frontend.

e2e/specs/album-dropdown.spec.ts

@@ -1,6 +1,12 @@
 import { test, expect } from '../support/fixtures.js';
 import type { Page } from '@playwright/test';
 
+/**
+ * How far the scroll test scrolls. One constant, because the guard and
+ * the assertion have to agree about it — they did not, which is #133.
+ */
+const SCROLL_TARGET = 80;
+
 /**
  * Plan 007 phase 5: expanding an album shows its tracks.
  *
@@ -104,20 +110,30 @@ test.describe('the album dropdown', () => {
     await app.setViewportSize({ width: 900, height: 600 });
 
     try {
-      await expect.poll(() => scrollRange(app)).toMatchObject({
-        scrollable: true,
-        overflowY: 'auto',
-      });
+      // The container has to be a scroller at all, which is the thing
+      // the defect behind this spec broke and is a property rather
+      // than a moment.
+      await expect
+        .poll(() => scrollRange(app))
+        .toMatchObject({ overflowY: 'auto' });
 
-      await app.evaluate(() => {
-        const sc = document
-          .querySelector('cover-grid')
-          ?.shadowRoot?.querySelector('.grid-scroll-container');
-
-        if (sc) sc.scrollTop = 80;
-      });
-
-      expect(await scrollTop(app)).toBe(80);
+      // **Scrolling it and reading it back are one round trip** (#151).
+      //
+      // #133 made the guard ask for the range this needs rather than
+      // for "scrollable at all", which was necessary and is not
+      // sufficient: a guard and the write it guards are separate
+      // `evaluate` calls, so the grid can satisfy the range and settle
+      // out of it before the write lands. It still does — observed as
+      // `Expected 80, Received 10` in the second of three consecutive
+      // full-suite runs, with the spec green alone on the same app
+      // straight afterwards.
+      //
+      // Polling harder cannot close a window between two moments; only
+      // removing the window can. So the probe sets `scrollTop` and
+      // returns what it reads back, in one page-side call, and the
+      // poll retries *that* — which also means the assertion is about
+      // what the grid did rather than about what it was ready to do.
+      await expect.poll(() => scrollTo(app, SCROLL_TARGET)).toBe(SCROLL_TARGET);
 
       // And the dropdown it opens is on screen, wherever the manager
       // decides that leaves the scroll. It is *not* "the position is
@@ -248,27 +264,45 @@ async function closeDropdown(app: Page): Promise<void> {
   });
 }
 
-/** Whether the grid can scroll at all, which decides if a probe can move. */
+/** Whether the grid is a scroller at all, which is what the bug broke. */
 async function scrollRange(app: Page) {
-  return app.evaluate(() => {
+  return app.evaluate((target) => {
     const sc = document
       .querySelector('cover-grid')
       ?.shadowRoot?.querySelector('.grid-scroll-container');
 
     return {
-      scrollable: !!sc && sc.scrollHeight > sc.clientHeight + 40,
+      // Reported for the failure message rather than waited on: `room`
+      // was the guard #133 strengthened, and #151 is that a guard in
+      // its own round trip cannot speak for the write in the next one.
+      // `scrollTo` below is the assertion now; this says *why* it did
+      // not reach the target when it does not.
+      room: !!sc && sc.scrollHeight - sc.clientHeight >= target,
       overflowY: sc ? getComputedStyle(sc).overflowY : '',
     };
-  });
+  }, SCROLL_TARGET);
 }
 
-async function scrollTop(app: Page): Promise<number> {
-  return app.evaluate(
-    () =>
-      document
+/**
+ * Scroll the grid and report where it actually landed, in one call.
+ *
+ * The whole point is that the set and the read share a moment: a
+ * `scrollTop` write is clamped to the range *at the instant it lands*,
+ * so reading it back in a second round trip asks a container that may
+ * have re-laid out in between.
+ */
+async function scrollTo(app: Page, target: number): Promise<number> {
+  return app.evaluate((to) => {
+    const sc = document
       .querySelector('cover-grid')
-        ?.shadowRoot?.querySelector('.grid-scroll-container')?.scrollTop ?? -1,
-  );
+      ?.shadowRoot?.querySelector('.grid-scroll-container');
+
+    if (!sc) return -1;
+
+    sc.scrollTop = to;
+
+    return sc.scrollTop;
+  }, target);
 }
 
 /** Whether the open dropdown is inside the scroll container's viewport. */

e2e/specs/back-navigation.spec.ts

@@ -15,12 +15,49 @@ import { test, expect } from '../support/fixtures.js';
  *
  * What it cannot answer is whether Android's *gesture* reaches the
  * WebView, which is between the OS and the scaffold.
+ *
+ * **And `data-active-view` is not the behaviour.** Every assertion here
+ * used to be that attribute, which the shell sets on every path
+ * including `_isBack` — so this file was green throughout #72, in
+ * which both navs highlighted the view the user had just *left*. The
+ * shell's own bookkeeping was the one thing that was already right;
+ * what a person sees is `aria-current`, and that is asserted below as
+ * well. This is the same trap `layout-overflow.spec.ts` set for #69: a
+ * spec named for the behaviour, measuring the plumbing.
  */
 type Page = import('@playwright/test').Page;
 
 const activeView = (page: Page) =>
   page.getByTestId('main-content');
 
+/** A common phone, where the bottom bar is the primary navigation. */
+const PHONE = { width: 390, height: 844 };
+
+/**
+ * The nav item for a destination, in whichever navigation is on screen.
+ *
+ * Both navs carry a button named `Albums`, and only one of them is ever
+ * in the accessibility tree — the other is `display: none` — so the
+ * role query resolves to the one the user can see at this viewport.
+ * That is the point: the highlight has to be right in both, and #72 was
+ * two different-looking symptoms of one cause.
+ */
+const navItem = (page: Page, label: string) =>
+  page.getByRole('button', { name: label, exact: true });
+
+/**
+ * `aria-current="page"` is the accessible fact and the assertion worth
+ * making; `.active` is a class and could be restyled without breaking
+ * anything real.
+ */
+async function expectHighlighted(page: Page, label: string): Promise<void> {
+  await expect(navItem(page, label)).toHaveAttribute('aria-current', 'page');
+}
+
+async function expectNotHighlighted(page: Page, label: string): Promise<void> {
+  await expect(navItem(page, label)).toHaveAttribute('aria-current', 'false');
+}
+
 /**
  * Open an artist's detail view, which is the deepest ordinary route.
  *
@@ -42,6 +79,114 @@ async function openAnArtist(app: Page): Promise<void> {
   );
 }
 
+/**
+ * The global back/forward control (#6).
+ *
+ * It is desktop chrome — hidden below 900px, where the sidebar has
+ * already given up its labels — so these set a desktop viewport
+ * explicitly rather than trusting the runner's default.
+ */
+const DESKTOP = { width: 1280, height: 800 };
+
+const backButton = (page: Page) =>
+  page.locator('nav-history').getByRole('button', { name: 'Back' });
+
+const forwardButton = (page: Page) =>
+  page.locator('nav-history').getByRole('button', { name: 'Forward' });
+
+test.describe('global back and forward', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(DESKTOP);
+  });
+
+  test('offers nothing at launch, in either direction', async ({ app }) => {
+    // The launch entry is *replaced*, not pushed, so there is nothing
+    // of ours behind it — and a Back button that is live at the root
+    // is a press that does nothing on desktop and, on Android, the
+    // press that should have exited the app (#142). This assertion is
+    // what pins that: it failed before the launch navigation stopped
+    // recording two entries.
+    await expect(backButton(app)).toBeDisabled();
+    await expect(forwardButton(app)).toBeDisabled();
+  });
+
+  test('walks the history in both directions, and says which are available', async ({
+    app,
+  }) => {
+    await app.getByTestId('nav-albums').click();
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+    await expect(backButton(app)).toBeEnabled();
+    await expect(forwardButton(app)).toBeDisabled();
+
+    await app.getByTestId('nav-tracks').click();
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'tracks');
+
+    await backButton(app).click();
+
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+    // Standing in the middle of the list: both directions live, which
+    // is the state a single depth counter cannot express.
+    await expect(backButton(app)).toBeEnabled();
+    await expect(forwardButton(app)).toBeEnabled();
+
+    await forwardButton(app).click();
+
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'tracks');
+    await expect(forwardButton(app)).toBeDisabled();
+  });
+
+  test('reaches the detail view a tab click left behind', async ({ app }) => {
+    // The report, exactly: the album is one entry away the whole time,
+    // and before this control the only way back to it was a button
+    // that had gone off screen with the view it belonged to.
+    await app.getByTestId('nav-artists').click();
+    await openAnArtist(app);
+
+    await app.getByTestId('nav-tracks').click();
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'tracks');
+
+    await backButton(app).click();
+
+    await expect(activeView(app)).toHaveAttribute(
+      'data-active-view',
+      'explore-artist-details',
+    );
+  });
+
+  test('drops the forward list when the user navigates from the middle', async ({
+    app,
+  }) => {
+    await app.getByTestId('nav-albums').click();
+    await app.getByTestId('nav-tracks').click();
+    await backButton(app).click();
+    await expect(forwardButton(app)).toBeEnabled();
+
+    // A browser truncates here, and so does this: what was ahead is no
+    // longer reachable, and a Forward button still offering it would
+    // be pointing at an entry that has been overwritten.
+    await app.getByTestId('nav-genres').click();
+
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'genres');
+    await expect(forwardButton(app)).toBeDisabled();
+    await expect(backButton(app)).toBeEnabled();
+  });
+
+  test('is absent below the desktop band, where nothing needs it', async ({
+    app,
+  }) => {
+    // Alt+Left/Right survive at every width, the detail views keep
+    // their own back buttons and the phone has the platform's gesture
+    // — so this is a control standing down, not an action becoming
+    // unreachable. It is hidden at 899 because the top bar is what
+    // runs out of room first below 900 (#143).
+    await app.setViewportSize({ width: 899, height: 600 });
+    await expect(app.locator('nav-history')).toBeHidden();
+
+    await app.setViewportSize({ width: 390, height: 844 });
+    await expect(app.locator('nav-history')).toBeHidden();
+  });
+});
+
 test.describe('the back gesture', () => {
   test('leaves a detail view for the view it was opened from', async ({
     app,
@@ -71,6 +216,105 @@ test.describe('the back gesture', () => {
     await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
   });
 
+  test('leaves the nav highlighting the view it landed on, not the one it left', async ({
+    app,
+  }) => {
+    await app.getByTestId('nav-albums').click();
+    await expectHighlighted(app, 'Albums');
+
+    await app.getByTestId('nav-tracks').click();
+    await expectHighlighted(app, 'Tracks');
+
+    await app.goBack();
+
+    // #72, and the half of it the report did not describe: this is
+    // desktop, and before the shell published the active view *both*
+    // navs stayed on Tracks. An absent highlight reads as a glitch; a
+    // confident wrong one is worse, and any back across two primary
+    // views produced it.
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+    await expectHighlighted(app, 'Albums');
+    await expectNotHighlighted(app, 'Tracks');
+  });
+
+  test('keeps the parent destination lit while a detail view is open', async ({
+    app,
+  }) => {
+    await app.getByTestId('nav-artists').click();
+    await expectHighlighted(app, 'Artists');
+
+    await openAnArtist(app);
+
+    // A detail view is not a destination in either nav, and the user is
+    // still inside Artists. `app-sidebar` did this by accident -- it
+    // guarded on its own item list, so an unmatched name left the
+    // highlight alone -- and that accident is why the sidebar looked
+    // right on a detail view while the tab bar lit nothing. This test
+    // therefore passed before the fix and is here to keep the rule from
+    // being lost while the others are made to pass; the *tab bar's*
+    // half of it is the phone test below, which did not.
+    await expectHighlighted(app, 'Artists');
+
+    await app.goBack();
+
+    await expectHighlighted(app, 'Artists');
+  });
+
+  test('the tab bar survives the same journey on a phone', async ({ app }) => {
+    await app.setViewportSize(PHONE);
+
+    // The reported shape: Albums, open an album, press back. The tab
+    // bar had a highlight, then no highlight at all, and never got it
+    // back — `bottom-nav` took the detail view's name, matched it
+    // against no tab, and lit nothing.
+    await navItem(app, 'Albums').click();
+    await expectHighlighted(app, 'Albums');
+
+    await app.locator('cover-grid').getByText('Glass Harbour').first().click();
+    await expect(activeView(app)).toHaveAttribute(
+      'data-active-view',
+      'explore-album-details',
+    );
+    await expectHighlighted(app, 'Albums');
+
+    await app.goBack();
+
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+    await expectHighlighted(app, 'Albums');
+  });
+
+  test('the drawer sidebar opens on the page you are standing on', async ({
+    app,
+  }) => {
+    await app.setViewportSize(PHONE);
+
+    await navItem(app, 'Tracks').click();
+    await expectHighlighted(app, 'Tracks');
+
+    // A third symptom of the same cause, found while measuring #72 and
+    // not in the report: `bottom-nav` mounts its `<app-sidebar>` when
+    // the drawer opens, so that copy had heard no `navigate` at all and
+    // showed its own default — Home, from any page in the app. An event
+    // has no answer for a listener that was not there; a store does.
+    await navItem(app, 'More').click();
+
+    // The element carrying the testid is the `wa-drawer` host, which
+    // always reports hidden -- what is visible is the `<dialog>` in its
+    // shadow root -- so the drawer being open is asserted of the
+    // sidebar it holds rather than of itself.
+    const drawer = app.getByTestId('nav-drawer');
+
+    await expect(drawer.locator('app-sidebar')).toBeVisible();
+    await expect(drawer.getByTestId('nav-tracks')).toHaveAttribute(
+      'aria-current',
+      'page',
+    );
+    await expect(drawer.getByTestId('nav-home')).toHaveAttribute(
+      'aria-current',
+      'false',
+    );
+  });
+
   test('an in-app back button consumes exactly one entry', async ({ app }) => {
     await app.getByTestId('nav-tracks').click();
     await openAnArtist(app);