docs(android): record the lifecycle model and the device check
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The lifecycle answer is load-bearing, so CLAUDE.md states it: an
activity is a view onto the process, and main() runs once per process.
The "restore the session or cold-start" question the issue asks for a
decision on is settled by playback rather than by preference -- the
audio lives in the Go process, so a cold start on every recreation
stops the music mid-song, which is the thing the foreground service
exists to prevent.

android-tier.md's build table said "arm64, real device -- unverified,
still" for five phases. It is verified now, on a Light Phone III
(Android 14, arm64-v8a, WebView Chrome 113 at 424x439), and what the
run found is a lifecycle section: how to force an activity recreation
on demand, the three-line logcat signature, why `has died: fg TOP` is
not a memory kill, and the second assertion that surviving does not
imply working.

It also carries the correction that "Don't keep activities" -- the
report's own suggested lever -- does not work on this device at all,
so nobody spends an afternoon on it. A configuration change the
manifest does not declare does, in one line.

And it stops recommending `wails3 task android:run:device`, which
uninstalls the released app and the user's library to install a build
with a different id (#159), in favour of the manual sequence.

NOTES.md carries the measurements, dated: 8 of 8 recreations fatal
before, 5 of 5 survived after, and the note that runs where no
recreation happened are inconclusive rather than passes -- a harness
that does not check for the second bridge init reports those as green
and reads as flakiness.

Refs #52, #159, #160
This commit is contained in:
2026-08-20 13:04:18 -04:00
parent d714bd7090
commit 8a757c9bb4
3 changed files with 253 additions and 4 deletions
@@ -194,9 +194,13 @@ 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 +214,11 @@ 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 +258,20 @@ 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:
> **Do not run `android:run:device` or `android:deploy-device`
> against a device that has the released app on it (#159).** Both begin
> with `adb uninstall {{.APP_ID}}`, and `APP_ID` defaults to
> `app.yellowjacket` — the **release** id — while `run:device` builds
> the **debug** variant, whose id is `app.yellowjacket.dev`. So it
> uninstalls the user's app, taking the library with it, installs a
> different package, and then fails to launch the one it removed. This
> is "the identity is declared twice" (below) cashing out. The safe
> sequence is at the end of this section.
```
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 # UNSAFE, see #159
wails3 task android:deploy-device # UNSAFE, see #159
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
@@ -287,6 +306,19 @@ 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.
**The safe way to put a debug build on a real device**, which is what
#52 used and what #159 exists to make unnecessary:
```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
```
`YJ_ANDROID_PKG=app.yellowjacket.dev` points `scripts/android-emulator.sh`
— and therefore `make android-smoke`, `android-logs`, `android-launch`
— at the debug id, which is otherwise `app.yellowjacket`.
## What only a device can answer
The emulator cannot run this app (three separate reasons, none of them
@@ -311,6 +343,91 @@ 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
+78
View File
@@ -4077,3 +4077,81 @@ have saved the other two cycles.
first track with no cover art" selects nothing in particular. The
placeholder's presence is asserted instead, which is the property the
test actually depends on.
## An activity recreation kills the process, deterministically (measured 2026-08-20)
#52's report was "sometimes crashes or restarts when reopened after
running in the background". Measured on a real device, the *fault* is
not intermittent at all — only its trigger is.
Device: Light Phone III (TLP301), Android 14 / SDK 34, arm64-v8a,
WebView **Chrome 113** at 424x439 CSS px. Debug build
(`app.yellowjacket.dev`), installed beside the released `v0.3.1` with
`install -r`.
**Conditional on the activity actually being recreated in a live
process, the process died 8 times out of 8** — 3 by hand, then 5/5 in a
scripted loop. The runs where it survived were runs where no recreation
happened (one `Wails bridge initialized` in the log rather than two), so
they are inconclusive rather than passes; a harness that does not check
for the second init reports those as green and reads as flakiness.
After the fix: 5/5 recreations survived, plus 6 background/foreground
cycles and 3 interleaved recreations on one pid.
The mechanism is three log lines:
```
12:47:56.159 I/WailsBridge(22956): Wails bridge initialized
12:48:38.898 I/WailsBridge(22956): Wails bridge initialized <- same pid
12:48:39.357 I/ActivityManager: Process app.yellowjacket.dev (pid 22956) has died: fg TOP
```
`nativeInit` runs `go mainFunc()` on every activity creation; the second
`main()` reaches `app.Run()`, which refuses because `a.starting` is
still true behind Android's `select{}`, and `os.Exit(1)` takes the whole
process — including the healthy first app — with it.
Four things worth keeping:
- **`has died: fg TOP` is not a memory kill.** The system does not
reclaim the foreground process. This reads as "the OS killed us",
which is the wrong hypothesis and the reason the issue sat unverified.
- **There is no crash record of any kind**: `logcat -b crash` empty, no
`AndroidRuntime`, no `libc: Fatal signal`, no tombstone. `os.Exit` is
not a crash. The one line that named the fault —
`slog.Error("application error", "err", ...)`, carrying
`"application is running or a previous run has failed"` — went to
`/dev/null`. That is #160.
- **"Don't keep activities" does 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. The report's own
suggested lever is a dead end here. What *does* work, deterministically
and in one line, is a configuration change the manifest does not
declare: `adb shell settings put system font_scale 1.15`
(`AndroidManifest.xml` declares `orientation|screenSize|
keyboardHidden|uiMode`, so none of those are triggers).
- **Surviving is only half the property.** The recreated WebView has to
still be wired to the running app, which was verified by hooking
`window._wails.dispatchWailsEvent` and backgrounding/foregrounding:
`["IndexStatusChanged","JobsChanged","JobsChanged",
"android:storageAccess"]`. The tempting Java-side fix — making
`WailsBridge.initialized` static — passes the pid check and fails
this one, because `nativeInit` is also what re-points the JNI
reference at the new bridge.
## The Taskfile's device tasks uninstall the released app (2026-08-20)
`android:run:device` builds the **debug** variant
(`applicationIdSuffix ".dev"`) and then runs
`adb uninstall {{.APP_ID}}`, where `APP_ID` defaults to
`app.yellowjacket` — the **release** id. So it deletes the user's
installed app and its library, installs a different package, and then
fails to launch the one it removed. `deploy-device` carries the same
uninstall. Filed as #159; `android-tier.md` had been recommending
`run:device` as the way onto a device.
This is the hazard that file already names — "The identity is declared
twice ... **Nothing enforces that they agree**" — reached by a second
route: the two ids differ not because someone edited one, but because
the debug buildType suffixes it.
+54
View File
@@ -317,6 +317,60 @@ stacking dialogs. Window state moved off that path entirely, onto a
window still exists and `OnShutdown` has neither a context nor a
window.
**An activity is a view onto the process, and `main()` runs once per
process.** On Android the Wails entry point is `nativeInit`, which
`MainActivity.onCreate` calls — and it does two things: it re-points the
native library's global JNI reference at the calling `WailsBridge`, and
it runs `go mainFunc()`. Android destroys and recreates an activity
**without restarting the process** (a configuration change the manifest
does not declare, memory pressure, or every background under "Don't keep
activities"), so `main()` ran again on a live app. `application.New`
returns the *existing* app rather than building a second one,
`app.Run()` then refuses — `a.starting` is still true, because Android's
`platformRun` is `select{}` and never returns — and the `os.Exit(1)`
under that error took the **first**, healthy app down with it: its
database, its queue, and the audio a `mediaPlayback` foreground service
was holding the process alive to play. `mainStarted` latches it, first
statement in `main()`.
Four things about it are load-bearing.
**The answer to "restore the session or cold-start" is settled by
playback, not by preference.** The audio lives in the Go process, so a
cold start on every activity recreation would stop the music mid-song —
which is the exact thing the foreground service exists to prevent. The
activity is a view; the app is the process. The frontend already
cooperates, because a recreated WebView loads the page fresh and fetches
its state from a backend that never went away.
**Returning early is not a degraded mode, and that is why the latch is
in Go rather than in Java.** The obvious fix — making
`WailsBridge.initialized` `static`, so the second `nativeInit` is
skipped — keeps the process alive and silently breaks the app, because
skipping `nativeInit` skips the reference re-point too: Go would keep
executing JavaScript against the *destroyed* activity's WebView, and the
app would open, render, and never receive another backend event. The
latch lets `nativeInit` do its first job and declines only its second.
**`ServiceShutdown` has never run on Android**, and nothing should be
built on the assumption that it will. `App.Quit()` reaches an
`androidApp.destroy()` that is an empty method, and `Run()`'s deferred
`shutdownServices()` cannot fire behind `select{}`. Durability on this
platform is the persist writers, which submit on every mutation rather
than at exit — which is also why `MainActivity.onDestroy` no longer
calls `bridge.shutdown()`: the activity going away is not the app
shutting down, and there is no callback for the process going away
because Android simply kills it.
**No tier here can see any of this**, so the guard is split. A source
sweep (`TestMainClaimsBeforeItDoesAnything`) asserts the latch is the
*first* statement of `main()` — the failure it exists for is not
deletion, which is loud, but a line creeping in above it, since a second
`NewYellowJacketApp` opens the SQLite database again on every
recreation. The rest is a documented device check in
`.pi/skills/yellowjacket-dev/references/android-tier.md`, with the
logcat signature and a one-line way to force a recreation.
`internalServiceMethods` auto-excludes `ServiceStartup`,
`ServiceShutdown`, `ServiceName` and `ServeHTTP` from bindings, so this
shape **removed** 12 spurious bindings and the bogus `context` model