yellowjacket/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project

YellowJacket is a cross-platform desktop music player built with Go (backend) and TypeScript/Lit (frontend), using the Wails framework to bridge them. It supports MP3, FLAC, OGG Vorbis, and WAV playback.

Planning

Active and historical plans live in .planning/:

• .planning/NOTES.md — gotchas, deferred items, open architecture questions, the "we already considered and rejected" list.
• .planning/plans/active/ — work currently in progress (read first).
• .planning/plans/pending/ — sequenced future work.
• .planning/plans/completed/ — one concise recap per shipped milestone.

Numbering is sequential and stable across status moves (a plan keeps its NNN- prefix as it migrates between pending → active → completed). Abandoned plans are deleted; paused work stays in pending/.

Commands

make dev              # Hot-reload development (installs deps, generates code, cleans frontend)
make dev-debug        # Same as dev but with YJ_LOG_LEVEL=debug
make dev-headless     # Start headless in the background and return (SEED=<name> to seed)
make dev-stop         # Stop it (SIGTERM, so shutdown hooks run)
make dev-logs         # Tail .dev/app.log
make testdata         # Generate the deterministic fixture music library
make sandbox-seed NAME=<n>  # Build a seeded YJ_HOME by *running* the app
make build-dev        # Debug build with symbols
make build-prod       # Production build (stripped, UPX-compressed)
make generate         # Run code generators (sqlc + templ via go generate)
make e2e              # Playwright smoke suite against a running dev-headless app
make e2e-setup        # Install the e2e runner + its browser (once)
make ui-test          # Vitest component/store suite in a real browser (no app)
make ui-visual        # Same, including toMatchScreenshot comparisons
make ui-setup         # Install the Vitest provider's own Chromium (once)
make bindings-check   # Fail if frontend/wailsjs is stale vs the Go bindings
make skill-check      # Fail if .pi/ documents a make target that doesn't exist
make lint             # golangci-lint v2 (strict), all three build configurations
make test             # All tests with race detector, all three build configurations
make vulncheck        # govulncheck for CVEs
make setup            # Install go tools, frontend deps, git hooks (lefthook)

Running tests

All Go test commands require the -tags webkit2_41 build tag:

go test -tags webkit2_41 ./...                           # All tests
go test -tags webkit2_41 ./backend/player/               # Single package
go test -tags webkit2_41 -run TestName ./backend/player/  # Single test

The central index builder is behind a second tag and is not covered by the command above — make test runs both passes, but a manual run needs it spelled out:

go test -tags "webkit2_41 indexbuild" ./backend/explore/... ./cmd/...

backend/testctl is behind a third tag and needs its own pass too (make test runs all three):

go test -tags "webkit2_41 dev" ./backend/testctl/...

Audio playback integration tests require YELLOWJACKET_INTEGRATION=1.

Fixtures and the headless harness

test_data/music_library_test/ is generated, not committed: run make testdata (~1 s) before anything that needs audio. Tests reach it through internal/testfixtures, selecting files by case (CaseCoverDedup, CaseUnicode, CaseDuplicates, …) rather than by path, and skip themselves when it has not been generated.

The app itself can be run without a blocking window — make dev-headless — and driven with playwright-cli against the dev server on :34115, which is the real app with real bindings on window.go, bridged to the same Go backend a desktop window would use.

The operational half of all this lives in the yellowjacket-dev skill (.pi/skills/yellowjacket-dev/): which tier to reach for, the exact command sequences, seed lifecycle, and the failure modes worth knowing before you meet them. It is deliberately not repeated here — this section describes what exists, the skill says what to run.

Two things ride on top of the headless launch, both from plan 005 phase 3:

• The event bridge. .playwright/cli.config.json loads .playwright/init-events.js as an initScript, which records every backend event on window.__yjEvents. Half this app is push-driven, so assertions await an event, not a timeout: await window.__yjEvents.wait('LibraryScanComplete', {timeoutMs: 60000}). It also provides ready() and call('queue.Queue.GetState', []), which times out instead of hanging.
• The dev-only control surface, backend/testctl, mounted at /__test/ on the same port: health, db/snapshot, db/restore, emit (force any backend event, which renders push-driven views without staging the work that would produce them) and sql. It is compiled out of non-dev builds and additionally requires YJ_TESTCTL=1, which dev-headless.sh sets and make dev does not.

Frozen regression specs live in e2e/ (its own npm package, so the Vitest browser mode does not share a package with the Playwright runner): make e2e against an already-running app.

The cheapest tier needs none of that. make ui-test runs 313 Vitest tests in a real Chromium in ~2 s with no Wails, no backend, no seeded library and no virtual display, because frontend/wailsjs/ is a pure passthrough to window.go / window.runtime and frontend/test/support/wails-fake.ts replaces just those two globals — so the tests exercise the real generated bindings and the real store code.

frontend/wailsjs/ is generated by wails, not go generate, so the pre-commit codegen check does not cover it. make bindings-check (~1.5 s, also a pre-commit hook) regenerates it and fails on a dirty tree; make bindings regenerates it for real.

Seeds are produced by running the app, never by hand-writing a config.toml and DB rows — the same discipline sql/schemas/ gets, for the same reason.

See .planning/plans/active/005-agent-development-harness.md.

Architecture

Wails app lifecycle (main.go → backend/app.go): YellowJacketApp is the root struct bound to Wails. Its methods are callable from the frontend. Lifecycle hooks: OnStartup (init audio), OnDomReady (start library scan), OnBeforeClose (save window state), OnShutdown (persist player/queue state).

Backend packages (under backend/):

• player — Audio playback via beep. BufferedStreamer provides a ring buffer for smooth seeking.

• queue — Track queue with shuffle (Fisher-Yates), repeat modes, auto-advance, and session persistence.

• library — Concurrent library scanning, metadata extraction, cover art deduplication, incremental rescan.

• database — SQLite via pure-Go driver. Schema in database/sql/schemas/, queries in database/sql/queries/. sqlc generates Go code into database/sql/sqlcgen/ — never edit that directory by hand.

  Schema changes need two things, not one. sql/schemas/*.sql is CREATE ... IF NOT EXISTS and is what sqlc reads — it's the single source of truth for "what the schema looks like right now", and it's what a fresh install gets verbatim. But it's a no-op against a database that already has the table, so an existing install needs a matching file in sql/schemas/../migrations/ (e.g. NNNN_description.sql, ALTER TABLE ... ADD COLUMN ... / CREATE INDEX ...) to actually reach that shape. Both run on every open, migrations after schema files, tracked in schema_migrations so each applies once; a migration's ALTER TABLE ADD COLUMN failing with "duplicate column name" on an already-current database is expected and tolerated, not an error.

  A few things that bite if forgotten:

  • Column order must match between the two paths. ALTER TABLE ADD COLUMN always appends at the end, so a migrated column must also be declared last in the CREATE TABLE in sql/schemas/ — otherwise a fresh install and an upgraded install disagree on column order, and a SELECT * query (sqlc binds those positionally) silently reads the wrong field on one of them. See backend/database/migrations_test.go's TestMigrations_ColumnOrderMatchesFreshInstall, which is the regression test for exactly this.
  • Don't put an index on a migrated column in sql/schemas/. Schema files run before migrations, against a database that may not have that column yet — the index's predicate would fail (this is precisely the bug an earlier session shipped and a user hit at make sandbox). Declare it in the migration file instead, after the ALTER TABLE that adds the column.
  • This project had a 48-step migration chain before and tore it out (see .planning/NOTES.md, "No migration chain") because sql/schemas/ had drifted from what the migrations actually produced and sqlc silently generated against the stale version. The design here avoids that by keeping sql/schemas/ as the literal target shape (not a hand-maintained description of it) and letting migrations replay tolerantly against it — but the same drift is possible again if a schema change ships without updating both files. Don't reintroduce a second description of the schema anywhere else.
  • Squashing is fine pre-1.0. While this hasn't shipped to real users, periodically folding sql/migrations/ into sql/schemas/ and deleting the migration files (then wiping your own dev/sandbox DB) is a legitimate way to keep the migrations directory from accumulating dev-only churn — same effect as the old "just nuke it" workflow, opt-in instead of mandatory. Stop doing that once real user databases exist in the wild.

• metadata — Tag extraction (ID3v2, Vorbis Comments, FLAC).

• config — TOML-based settings. Settings page uses HTMX + templ for server-rendered HTML fragments.

• playlist / smartplaylist — Playlist CRUD and rule-based smart playlists.

• mediacontrols — MPRIS integration on Linux via D-Bus.

• system — OS-specific paths (XDG on Linux, %LOCALAPPDATA% on Windows).

• explore — Catalog search and browse over explore_index. See below.

• home — The home page's "start listening" shelves. Each shelf is a reason (what you played last, what you never played, a genre you have depth in) rather than a filter, and carries the sentence that says so. Its queries (sql/queries/home.sql) return album ids only and are joined back to GetAllAlbumsWithDetails in Go, so the album projection has one definition. A shelf with nothing behind it is omitted, never rendered empty.

• profiling — pprof server on :6060, compiled out in non-dev builds via build tags (internal/dev/).

Explore catalog (backend/explore/): the searchable MusicBrainz/ ListenBrainz catalog in explore_index. Deriving it from the MetaBrainz dumps means streaming ~89 GB from a server that caps a client near 2 MB/s — half a day, for a catalog identical for every user. So that work happens once, centrally, and users download the result:

• cmd/indexbuild builds the catalog from the dumps; cmd/indexexport cuts it down to a shippable core and stamps its provenance. .gitea/workflows/index-artifact.yml runs both and publishes the compressed artifact under a fixed latest version.
• The app fetches and merges that artifact (artifactfetch.go, artifactimport.go) — about a minute, versus a day.
• Everything the app does not need is behind the indexbuild build tag (dumpimport.go, dumpcounts.go, dumpcatalog.go, dumpproject.go, dumpparallel.go, indexpatch.go) so it is not linked into the binary. dumpbuild_stub.go is the app-side entry point; dumpshared.go holds what both sides use.
• The app keeps popularity current with the daily incremental dumps (dumpincremental.go), and resolves artists outside the artifact's coverage lazily on first view.

Frontend (frontend/): Lit 3.2 web components + Web Awesome UI library + HTMX. State management via singleton reactive stores in src/store/. Wails bindings auto-generated in frontend/wailsjs/ — don't edit by hand.

Two cross-cutting pieces of that UI are worth knowing before touching a list or a detail view:

• utils/explore-link.ts renders every track/album/artist name in the app. A name always navigates: to the MusicBrainz page when the entity is tagged, and to the library page for the same thing when it is not (explore-album-details and explore-artist-details both accept a local id instead of an MBID). It fires on a genuine single click only — the navigation is held for one double-click interval and dropped if a second click arrives, because the title is the widest thing in a row and double-clicking a row plays it. Rows do not need to know links exist.
• <catalog-scope-notice> is how a detail page admits what it is showing: catalog data (silent), a library stand-in while a fetch is in flight, library-only because the entity has no MBID, or a failed/ empty catalog answer with a retry. Both detail views track catalogPending/catalogLoaded separately from their loading flags, since "something is renderable" and "this is the catalog's answer" are different questions.

Event-driven communication: Backend emits events via Wails runtime; frontend stores subscribe to them. Event names are constants in backend/events/.

Emit through events.Emit(ctx, name, data...), never runtime.EventsEmit — wails log.Fatalfs (unrecoverably) on any context that does not carry its runtime, which includes every context.Background(), so a direct call cannot run under test and can kill the app from a background worker. TestNoDirectRuntimeEmits fails the build on a direct call anywhere outside backend/events.

That wrapper is what makes services testable in-process: install a recorder with events.WithSink(ctx, rec) and assert on the payload the frontend would receive (backend/queue/emit_test.go is the model). events.Deliver is the same call returning an error instead of dropping, and has one legitimate caller — /__test/emit.

Code Generation

Two generators run via go generate ./... (or make generate):

1. sqlc — SQL → Go. Config at backend/database/sqlc.yaml. Add queries in backend/database/sql/queries/, get generated Go in database/sql/sqlcgen/.
2. templ — .templ files → *_templ.go files (same directory).

Pre-commit hooks verify generated code is fresh — always run make generate after changing .sql or .templ files.

Code Style

• Go: golangci-lint v2 with strict linters including err113 (static errors), nlreturn, wsl_v5 (whitespace), godot (comment periods), sloglint, perfsprint. Imports grouped: stdlib → third-party → yellowjacket/... (enforced by gci).
• TypeScript: Strict mode, no implicit any, no unused locals/parameters.
• Commits: Conventional commits format (enforced by commitlint in CI). Semantic release uses these for versioning.

Testing

Tests use database.NewTestDB(t) for in-memory SQLite, built by the same applySchema production uses so the two cannot diverge. Test audio fixtures live in test_data/music_library_test/. Table-driven tests are the norm.

Git Workflow

Feature branches and PRs are the norm, but direct pushes to main are allowed. Pre-commit runs vet, lint, codegen check, and frontend typecheck in parallel. Pre-push runs the full test suite.

CI

Four workflows in .gitea/workflows/. Three of them package and publish (arch-package, homebrew-formula, index-artifact); only ci.yml gates, and it is the one to look at when deciding whether a push was healthy.

Two jobs, both in an ubuntu:24.04 container:

• check — no display: make lint and make test (three build configurations each), tsc --noEmit, make ui-test, make bindings-check, make skill-check.
• e2e — under Xvfb and a private D-Bus: fixtures, a seed built by running the app, make dev-headless, then the Playwright suite against both Chromium and WebKit. Playwright's Linux WebKit links Ubuntu 24.04 libraries that Arch does not provide, so CI is the only place it can run, and it is the closest available approximation of the WebKit2GTK renderer that ships.

Two things the container needs that a developer machine does not. It has no PulseAudio socket, so /etc/asound.conf makes ALSA's null plugin the default device — that plugin advances its pointer on a timer, so playback is consumed at real-time rate and the elapsed clock moves, which e2e/specs/playback.spec.ts asserts. And YJ_CORE_INDEX_URL points at a dead address so no run fetches the real explore artifact, matching what scripts/seed-sandbox.sh already does.

make lint's tag sets must stay identical to make test's. Without webkit2_41 wails resolves webkit2gtk-4.0, which Arch still ships and Ubuntu 24.04 does not — so a mismatch lints a configuration that only builds on one developer's distro, and says nothing about what ships.