android: the handoff — the pending rounds, the pipeline, and what is unverified

Everything written this session that has not been through the device: rounds 43
to 48 (each patch adversarially verified, 43's transient-notice expectation
fixed), a partial round 49, the pipeline scripts, the Android Auto design and
the icon comparison mock. Also the two harness changes that were never A/B'd —
adaptive waits, which may only shorten a declared wait and never lengthen it,
and a ship that runs the mock walk and the deploy at the same time. The A/B and
its 255-step baseline are in handoff/tools; main stays at what the phone has
actually walked.

handoff/rounds/ins-r49-doc-auto.txt

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+- **Android Auto can see the app, and there is nothing inside.** Round
+  forty-nine made `MediaService` a `MediaLibraryService`, put three actions
+  on one intent filter (media3's `MediaLibraryService` and
+  `MediaSessionService`, plus the legacy
+  `android.media.browse.MediaBrowserService` that Auto actually binds), and
+  added `res/xml/automotive_app_desc.xml` with the
+  `com.google.android.gms.car.application` meta-data that declares the app to
+  Auto. So Auto lists SoulStream, opens it, and gets a root — immediately,
+  from `Futures.immediateFuture`, with nothing on the main thread — and the
+  root is empty. `onGetChildren` is not overridden, so the default answers
+  `ERROR_NOT_SUPPORTED` and the tree is one browsable folder with no rows in
+  it. What is still missing is everything under it: the library read out of
+  the database **read-only** from a process with no Activity and no Tauri
+  (`crates/library` is plain rusqlite and `JNI_OnLoad` publishes the Context
+  at `System.loadLibrary` time, so browse can work cold), playing what it
+  lists — which needs `COMMAND_SET_MEDIA_ITEM` and its neighbours, still
+  deliberately unadvertised, plus the `queueBase` → `playQueueAt()` mapping —
+  and search. Catalog and Soulseek rows will never play from cold: the
+  resolver is 872 lines of shared JS and Soulseek needs a live session, so
+  they get `STATE_ERROR` with a resolution intent instead, which is also what
+  Google's quality bar asks for. The walk proves the two front doors resolve
+  (`auto-browse`, `auto-library`) and `tools/auto-prober/` proves the root
+  comes back cold; the car screen itself still needs the Desktop Head Unit or
+  a car.