docs: record what shipping the release pipeline taught us

Moves plan 017 to completed with a recap, and lifts the three findings
that generalise into NOTES.md: a preset major that renders empty notes
with everything green, a 403 that looks like branch protection and is a
token scope, and tag-triggered workflows running the tagged commit's
own definitions.

.planning/plans/completed/017-release-automation.md

@@ -0,0 +1,87 @@
+# 017 — Releases that happen by themselves
+
+**Shipped as `v0.0.1`.** A merge to `main` now reads the Conventional
+Commits since the last tag, cuts the tag and the Gitea release whose body
+is the generated changelog, and the four publishing workflows build that
+tag and attach their artifacts. Nothing is released by hand.
+
+## What it looks like now
+
+`release.yml` on push to `main` → semantic-release → tag → four `v*`
+workflows in parallel (serialised in practice by the capacity-1 runner):
+
+| workflow | publishes | attaches |
+| --- | --- | --- |
+| `arch-package` | pacman registry | `…-x86_64.pkg.tar.zst` |
+| `android-apk` | generic registry (Obtainium) | `…-android-arm64.apk` |
+| `desktop-assets` | — | `…-linux-amd64.tar.gz` |
+| `homebrew-formula` | the public tap | — (builds from source) |
+
+Verified on the real thing: all five green, three assets on the release,
+the tap at `0.0.1`, and the Obtainium `latest` URL serving 200.
+
+## The five decisions, and what they cost
+
+1. **semantic-release, not a shell script.** The first draft of this plan
+   proposed hand-rolling it and the argument did not survive checking:
+   `@semantic-release/exec` is first-party and current, and the
+   Gitea-shaped part is one `curl`. What I would have hand-rolled —
+   commit parsing, semver ordering, note rendering — is the part with the
+   edge cases and none of it is Gitea-shaped.
+2. **`@saithodev/semantic-release-gitea` is a dead end** and was offered
+   before it was checked: last published 2022, `got@10`, and no peer
+   dependency on semantic-release at all.
+3. **No `@semantic-release/git`.** `main` is protected, so a changelog
+   commit-back is rejected by the pre-receive hook — and would be
+   rejected *after* the tag was pushed, leaving a tagged release the run
+   reports as failed. The release page is the changelog;
+   `.release-notes.md` is a gitignored carrier and `CHANGELOG.md` is a
+   signpost.
+4. **Versions restart at `0.0.1`**, a downgrade on every channel. No
+   `epoch`, no `versionCode` offset: both are permanent, a reinstall is
+   once. Documented in `packaging/homebrew/README.md` and
+   `docs/android-release.md`.
+5. **No macOS and no Windows.** `GOOS=darwin CGO_ENABLED=0` fails at
+   `wails/v3/pkg/mac` and there is no macOS runner, so Homebrew-from-source
+   stays that channel. Windows cross-compiles in ~2.5 s and is withheld
+   because no build of it has ever been *run*.
+
+## Four things that only showed up by running it
+
+- **`conventional-changelog-conventionalcommits@10` renders empty
+  notes.** Silently: right version, right tag, every step green, and a
+  release body that is a bare `## 0.0.1 (date)` heading with nothing
+  beneath it. Held at `9`, in `release.yml` and `make release-dry`, with
+  the reason beside both. **Check the rendered notes, never the exit
+  code.**
+- **semantic-release core dry-run-pushes to the release branch** as a
+  permission check, independently of any plugin. `PACKAGE_TOKEN` had
+  package-write and repo-*read* — enough to clone, not enough for this —
+  and it failed with a flat `403 Forbidden` that reads exactly like
+  branch protection. It is not: a `--dry-run` push never reaches the
+  pre-receive hook, which a one-line experiment settled. The token needed
+  `write:repository`.
+- **The floor tag must go on `HEAD^`, not `HEAD`.** Seeded on the merge
+  commit itself it leaves nothing between the floor and HEAD, and
+  semantic-release correctly reports there is nothing to release. The
+  first run did exactly that and cut nothing.
+- **A tag-triggered workflow runs from the tagged commit's tree.**
+  Moving `v0.0.0` back to `6fb7b5e` ran the *pre-merge* homebrew
+  workflow, which predates the `v0.0.0` skip guard, and pushed a `0.0.0`
+  formula to the public tap. Self-corrected at `0.0.1`. The corollary is
+  general: a guard added today does not protect a tag pointing at
+  yesterday.
+
+## Two mechanisms confirmed, having been assumptions
+
+- **A tag pushed with a user PAT does start the `v*` workflows**; one
+  pushed with the Actions token does not (go-gitea#33123). Both halves
+  are load-bearing and both were observed: the floor seed triggered
+  nothing, and the release tag triggered all four.
+- **Tags are not protected** on this repo, only `main` — which is what
+  lets semantic-release tag at all.
+
+## Left behind deliberately
+
+`v0.0.0` stays on `origin` as the floor. It carries no release, and all
+four publishers skip it by name.