Two harness bugs and the finding that exposed them.
**`pidof` exits 1 when it finds nothing**, and under `set -e` a failing
command substitution killed the script before it could print anything
-- rc=1, no output. That was invisible for as long as the app
crash-*looped*, because there is always some pid in that state. It
appeared the moment the app died for good and ActivityManager stopped
respawning it, which is precisely the run you most want output from.
**And an install failure said nothing useful.** Both ways it fails are
about identity rather than the build: INSTALL_FAILED_VERSION_DOWNGRADE
when a bare `make android` (versionCode 1) meets something a versioned
build left behind, and a signature mismatch when a debug-signed local
build meets a release-signed one. Both were hit in one session, and
both are fixed by uninstalling. The target says so now instead of
leaving someone to read the constant name.
The finding: with the startup bug fixed the app reaches the database
and takes SIGSYS on the x86_64 emulator, because modernc.org/libc's
Xlstat64 issues a raw lstat syscall on linux/amd64 and Android's
seccomp filter forbids it -- bionic never issues it. arm64 has no lstat
syscall at all, so ccgo_linux_arm64.go routes Xlstat through fstatat
and is structurally unaffected; Go's own syscall package already used
fstatat on both.
So the default emulator cannot verify this app, and the skill says so
rather than letting the next session read a tombstone as a regression.
The APK installs and launches. It also dies six milliseconds later, and
finding that out cost a cycle for three reasons that have nothing to do
with the bug itself:
**Go's stdout does not reach logcat.** An Android app's fd 1 and 2 go
to /dev/null, so every slog line -- including the one naming the error
the app is about to exit on -- is discarded. `setprop
log.redirect-stdio true` does not help: that redirects the Java
runtime's System.out, and our code is a c-shared native library.
**os.Exit leaves no evidence.** No panic, no AndroidRuntime stack,
nothing in /data/tombstones, nothing in `logcat -b crash` or dropbox.
All three places anyone would look are empty, and the one signal that
is present -- "Zygote: exited due to signal 9" -- reads as "the system
killed it" and sends you after the low-memory killer.
**ActivityManager restarts it faster than you can observe.** pidof
always answers and `am start` always reports Status: ok, so a
crash-looping app looks alive. "Did it start" is the wrong question;
`make android-smoke` asks whether it is the *same pid* N seconds later,
and prints the filtered logcat plus how to read it when it is not.
The tell, once known: "I/WailsBridge: Wails bridge initialized"
followed immediately by a new pid doing the same thing.
scripts/android-emulator.sh follows dev-headless.sh's shape --
background start, saved-PID stop, filtered log tail, never pkill -f.
Two scaffold tasks 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 is lowercase) and
misses ActivityManager's "has died" line, which is the one that says it
crashed; and `ensure-emulator` boots whatever `-list-avds | tail -1`
returns, with no pidfile and no boot wait, so it cannot be sequenced.
One environment note that is not obvious on Arch: Gradle needs a
platform and /opt/android-sdk has none, so ANDROID_SDK defaults to
~/Android/Sdk while ANDROID_NDK points at /opt/android-ndk. Two SDKs,
one for each half of the build.
logan