KeelrLeek
54245a33b5
"Recent" answered with TRACKS out of the `plays` table, and on a phone whose
history had just been wiped that was "No items" sitting over a full library —
the first thing a driver sees, saying the app has nothing.
Three changes, each about what the word means in a car.
**Albums, not tracks.** "Recent" in a car is "put that back on", and what
anyone means by that is the record. A list of single songs plays one and stops.
`plays` records what was played by NAME rather than by track id, so getting
back to an album means matching the pair again; anything played that has since
left the library drops out of the join, which is right for a row whose promise
is that tapping it works.
**Playlists, which were absent entirely.** They are in the database, they are
local, and they play from cold exactly as albums do — they were missing only
because the four root slots were spent, and Recent is somewhere they can live
without taking one. Counted out of `playlist_items` rather than
`playlist_tracks`: it is the richer table and the one that knows whether an
entry is a local file or something that needs the resolver. A playlist that is
part catalog says so on the row — "Playlist · 4 of 9 here" — so the gap is
declared before the tap rather than discovered after it, and tapping plays the
local entries in order. Entries that need the phone are shown rather than
hidden, so the car's list matches what is on the phone, and marked unplayable
rather than pretending.
**An unplayed library is not an empty shelf.** With no history at all, Recent
falls back to the newest albums, which is a defensible reading of the word and
a great deal better than an empty tab on a fresh install.
`ss:playlist:<id>` and `ss:pitem:<id>` join the tree and `resolve_playable`, so
a playlist or one of its tracks plays with the rest behind it.
Two fixes to the instrument that found this: `probe.sh` was passing
`--es play ""` when no query was given, which `am start` rejects outright
("Argument expected after play") — it is conditional now. And a splice left
`fn track_node(fn track_node(` in the source, which rustc reports as an
unclosed delimiter at the END of the file, pointing 400 lines away from the
mistake.
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.