docs(android): companion release + App-Not-Installed runbook

Capture the 2026-06-26 lessons durably: ship via the hardened publish
script only, v1+v2+v3 signing is enforced by apksigner (AGP ignores
enableV1Signing at minSdk>=24), diagnose install failures with adb
install FIRST, signature-key changes force a one-time uninstall, and
keep all phone/adb work scoped to com.archipelago.app.debug.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Android/COMPANION_RELEASE.md

@@ -0,0 +1,94 @@
+# Companion App — Build, Ship & "App Not Installed" Runbook
+
+Canonical procedure for releasing the Archipelago Companion Android app and for
+debugging install failures. Read this before touching the companion release flow.
+Hard lessons from 2026-06-26 are baked in below — don't relearn them.
+
+## Ship the companion (the only sanctioned way)
+
+```bash
+./Android/ship-companion.sh
+```
+
+This calls `scripts/publish-companion-apk.sh` (the single source of truth, also
+used by the `.githooks/pre-push` hook), which:
+
+1. **Removes/rejects resource dirs whose names contain spaces.** Empty stray
+   `mipmap-* NNN` dirs (left by icon-export tools) break a *clean* build with
+   `Invalid resource directory name`. Incremental builds hide them — clean builds
+   don't.
+2. **Always does a CLEAN build** (`:app:clean :app:assembleDebug`).
+3. **Forces v1 + v2 + v3 signing** via `zipalign` + `apksigner`.
+4. **Verifies all three schemes** (`apksigner verify --min-sdk-version 21`) and
+   **aborts** if any is missing.
+5. Stages the signed APK at `neode-ui/public/packages/archipelago-companion.apk`,
+   commits, and pushes with `SHIP_COMPANION=1` (the sanctioned pre-push bypass).
+
+**Never** hand-roll `gradlew assembleDebug` + `cp` to the served path. That path
+skips the clean build and the signature enforcement and is exactly how a broken
+APK shipped.
+
+### Bump the version first
+Edit `Android/app/build.gradle.kts` — `versionCode` (must strictly increase) and
+`versionName`. The committed value can drift AHEAD of what's actually built into
+the served APK, so verify the served APK's real version after shipping:
+`aapt2 dump badging neode-ui/public/packages/archipelago-companion.apk | grep version`.
+
+## Signing facts (important)
+
+- Debug builds are signed with the **committed** `Android/app/debug.keystore`
+  (store/key pass `android`, alias `androiddebugkey`) so every machine and the
+  served download share ONE signing key. Cert SHA-256: `D6:22:E0:7E:…:66:4D`.
+- **AGP silently ignores `enableV1Signing = true` for `minSdk ≥ 24`**, so a plain
+  gradle build produces a **v2-only** APK. The `apksigner` step in the publish
+  script is what actually guarantees v1+v2+v3 — do not remove it.
+- **Changing the signing key forces every existing install to be uninstalled
+  once.** Android blocks in-place upgrades across different signatures. Treat the
+  keystore as permanent; never regenerate it casually.
+
+## Debugging "App Not Installed" — DIAGNOSE FIRST
+
+Do **not** theorize about signing schemes / OEM quirks. Get the real reason:
+
+```bash
+adb install ~/Desktop/archipelago-companion-<ver>.apk
+# -> Failure [INSTALL_FAILED_<REASON>: ...]
+```
+
+Map the reason:
+
+| `INSTALL_FAILED_*` | Cause | Fix |
+|---|---|---|
+| `UPDATE_INCOMPATIBLE … signatures do not match` | Old install signed with a **different key** (e.g. pre-shared-keystore per-machine key `58:31:12…`). | Uninstall the old package, then install. **One-time** per device after a key change. |
+| `INVALID_APK` / parse error | Corrupt/incomplete download or bad signing. | Re-download; re-run the publish script. |
+| `INSUFFICIENT_STORAGE` | Storage. | Free space. |
+| `OLDER_SDK` | Device below `minSdk` (26 = Android 8.0). | Unsupported device. |
+
+> A manual uninstall on the phone may NOT clear `UPDATE_INCOMPATIBLE` if the
+> package is registered under another user/profile — `pm path <pkg>` under user 0
+> can show nothing while the conflict persists. `adb uninstall <pkg>` clears it
+> across all users.
+
+## Phone / adb safety (non-negotiable)
+
+When acting on the user's physical phone, be surgical — the user once had all
+home-screen app layouts wiped by an over-broad action.
+
+- Default to **read-only** adb (`devices`, `getprop`, `pm path/list`, `dumpsys`).
+- Mutations (`adb install`, `adb uninstall com.archipelago.app.debug`) only with
+  explicit go-ahead and **scoped to our exact package** — echo it first.
+- **Never** run launcher/system resets: no `pm clear` on launchers, no
+  `reset-permissions`, no factory wipe, no uninstalling apps you didn't build.
+
+## Verify the published download after shipping
+
+The download served to nodes is Gitea raw-on-main. Confirm the live bytes match
+what you built and signed:
+
+```bash
+SERVED=neode-ui/public/packages/archipelago-companion.apk
+URL=http://146.59.87.168:3000/lfg2025/archy/raw/branch/main/$SERVED
+curl -sS -o /tmp/live.apk "$URL"
+shasum -a 256 "$SERVED" /tmp/live.apk          # must match
+apksigner verify -v --min-sdk-version 21 /tmp/live.apk | grep -i "scheme"  # v1/v2/v3 = true
+```