KeelrLeek
8f46f9c663
Every entry in a streamed playlist is `kind='stream'` with no file on this phone — only a catalog id. A service-only process cannot turn that into audio: the resolver is hundreds of lines of shared JS that exist while a WebView does and not otherwise. So the car tapped those rows and nothing happened, which is the worst of the three possible answers. Now the process asks whether the APP can do it instead. Rust, finding nothing local, reports WHICH playlist and entry were meant rather than just failing — a catalog row is not a broken row, it is one this process cannot do alone, and that difference is what decides between an error and a hand-off. Kotlin carries it over `MediaHub.onRemote`, which is non-null only while the plugin is loaded, which is only while a WebView exists: the same fact is both the channel and the test for "is the app warm". And the JS plays it with `playFrom(playlist, items, item)` — the exact call the half-sheet makes when the same row is tapped in the app, so the queue, the provenance and the failure message are the app's own. Nothing about the car is special once it arrives. Cold, it says so instead of pretending: the focus is handed back rather than held for silence, and the log names the row. A phone in a pocket genuinely cannot play a Deezer id, and a tap that quietly does nothing is worse than one that stops. Two things the same change fixed on the way past. A streamed entry has no cover FILE, only a remote URL, so `COALESCE(art_path, art_url)` gives those rows their sleeves and a remote uri now goes to the host untouched instead of through a FileProvider whose root check it could never pass. And Recent, playlists and an artist's albums join Albums as GRIDS — all four are things known by the picture, which is what the grid is for. `probe.sh` gained `SS_KEEP=1`, without which the warm path cannot be tested at all: the script force-stops SoulStream, which is precisely the app the hand-off needs alive. **Proven:** cold answers `auto cold, cannot resolve` and releases focus; warm answers `auto hand-off to the app` and the event reaches the JS with no console error. **Not proven:** that the audio then starts. Those Deezer ids have to go through the resolver exactly as they do when tapped in the app, and if the app cannot play them the car will not either — which is correct behaviour and indistinguishable, from here, from a bridge that silently failed. It wants checking with the app in front of you.
The Android Auto prober
A throwaway app that binds SoulStream's MediaBrowserService the way Android
Auto does, walks whatever tree comes back, and prints one JSON object per
event under the logcat tag SoulAutoProbe.
bash tools/auto-prober/probe.sh # depth 2, the ordinary root
bash tools/auto-prober/probe.sh 3 true # depth 3, the RECENT root
adb uninstall com.soulstream.autoprober # and it is gone
Why it exists
Android Auto reaches a media app through MediaBrowserService, with the
app's process cold — no Activity, no WebView, and therefore no DevTools
socket. tests/mobile/smoke.mjs drives the phone over CDP, so it cannot see
any of this: with SoulStream force-stopped there is nothing for it to attach
to. Without a head unit or the Desktop Head Unit, this is the only instrument
the project has.
It is framework-only on purpose — android.media.browse.MediaBrowser, not
androidx, not media3. That is the path Auto itself takes into a media3 app
(media3 serves the legacy android.media.browse.MediaBrowserService action
through MediaSessionService.onBind), and a prober built out of the same
library as the thing it probes would not prove that path works.
Where it lives, and why not in the generated project
src-tauri/gen/android/ is regenerated by npx tauri android init and is
gitignored; anything put in there is deleted the next time someone runs it.
So the prober is its own Gradle build, tracked, outside it — and it borrows
the generated project's wrapper rather than shipping one, which pins Gradle
8.14.3, AGP 8.11.0, Kotlin 1.9.25 and JDK 17: exactly what is already in the
Gradle cache, so a probe run downloads nothing.
There is deliberately no gradle-wrapper.jar in this directory.
What it prints
One line per event, each a JSON object, all under SoulAutoProbe:I:
ev |
what it says |
|---|---|
start |
the package, component, depth and whether the RECENT root was asked for |
desc |
the com.google.android.gms.car.application meta-data resolved to a resource id, that resource's name, and the <uses name=…> inside it |
filter |
what queryIntentServices resolves for the legacy browse action and for media3's own, scoped to SoulStream |
root |
the number this exists for: milliseconds from connect() to onConnected() with the process cold, the root media id, and whether a session token came with it |
children |
one per subscription: the parent, how many rows, and each row's id, title, browsable and playable |
fail |
the bind failed, was suspended, or the 8 s watchdog fired |
done |
the walk finished: elapsed, nodes, leaves |
desc is the important one for the manifest, because adb shell pm dump
prints resolver tables and package state and no application meta-data at
all — the phone walk's auto-browse and auto-library checks can prove
the intent filters and nothing else. This resolves the meta-data int through
PackageManager.GET_META_DATA and then opens the resource out of the app's
own Resources, which is the only way to tell a real declaration from a
dangling id without unpacking the APK.
probe.sh also prints two lines of SoulStream's own log: auto root …, the
service's view of the same connection (including which root hints survived
the trip), and auto service created n=…, which is the androidx/media #3158
counter — see below.
androidx/media #3158
Open since 2026-04-03, still open, reproduced on media3 1.11.0: a host that
binds a MediaLibraryService while nothing is playing can put the service
into an onCreate → onBind → onGetSession → onConnect → onDestroy loop at
about thirty cycles a second. It is 100% reproducible after a force-stop with
no existing binding — which is precisely what this prober does, so expect to
see it here first.
MediaHub holds the session, the player, the notification provider, the
audio-focus request and the becoming-noisy receiver for the life of the
process, so a cycle allocates and registers nothing and the loop is survivable.
The loop itself is Android Auto's to fix and media3 has said it will not act
first. auto service created n=… is how you find out: one or two is normal, a
number climbing while a probe or a car is connected is the bug.
What it is not
It does not prove the car screen. Nothing here can: the Desktop Head Unit or a real head unit is the only thing that shows what Auto actually draws, how it groups a tree, or whether a tap plays. This proves the app answers.
Safety
No permissions beyond <queries>, no network, no storage, no transport
command. Every exit path disconnects the browser and onDestroy disconnects
again, so nothing is left bound to SoulStream's service. The only force-stop
probe.sh issues is of com.soulstream.app, which tests/mobile/smoke.mjs
already does on every phone run.