Why

Google rejected v2.8.0-closed.2 (versionCode 29321269) — "App crashes / the content of your application is not able to load" under the Auto App Quality Guidelines.

Root cause: the car app is a "templated messaging experience" (CarAppService MESSAGING + MessagingStyle notifications + <uses name="template" />). Per Google's docs, templated messaging is beta — publishable to Internal/Closed tracks only; Open/Production submissions are auto-rejected regardless of correctness. The crash is in the templated surface (launched by tapping a message notification → renders HomeScreen). The #5997 TabTemplate fix was already in the rejected build — it crashed anyway, and adding the com.google.android.gms.car.application meta-data there is what first exposed the templated app to review.

Reproduction is blocked locally: the DHU (2.1) can't launch sideloaded apps (CAR.VALIDATOR: Package DENIED; failed all other checks for every non-Google app, even with unknown-sources on), and Auto-host crashes don't reach Crashlytics/Datadog. R8 code-strip and resource-shrink were ruled out (all car code/resources survive the minified release build).

So this design can never reach Production. This PR makes the default build notification-only (GA, production-safe) and parks the templated experience behind a flag for Closed-track builds.

🌟 Production: notification-only car messaging

• Default googleRelease ships notification-only: CarAppService is android:enabled=false and automotive_app_desc declares only <uses name="notification" />. It is therefore not a templated Auto app and is not subject to the Auto templated review.
• Hands-free reply / mark-as-read keep working — that notification code lives in core:service, which is in every build.

🛠️ Templated dashboard parked behind -PenableCarTemplates

./gradlew :androidApp:bundleGoogleRelease                            # Production (notification-only)
./gradlew :androidApp:bundleGoogleRelease -PenableCarTemplates=true  # Closed track (+ templated)

• The flag adds androidApp/src/googleCarTemplates/res, whose automotive_app_desc override declares <uses name="template" />, and enables the service.
• feature:car stays compiled (FlavorModule references FeatureCarModule). It resolves the enabled placeholder from the same property, because a library's own manifest placeholder is not overridden by the app's value.

🐛 Crash hardening

• HomeScreen.onGetTemplate() now degrades to a safe template instead of throwing out to the Android Auto host (which crashes it = Play rejection). NOTE: a host-side template-contract rejection wouldn't throw here — the suspected TabTemplate-vs-ListTemplate/SectionedItemTemplate-of-ConversationItem contract issue still needs the Play Console pre-launch stack to confirm. Templated is parked until then.

Testing Performed

• aapt-verified the packaged manifest + automotive_app_desc: flag-off → service enabled=false + notification-only; flag-on → service enabled=true + <uses template>.
• spotlessCheck, detekt, assembleDebug (google + fdroid), :feature:car:test (CarScreensTest: disconnected→PaneTemplate and connected→TabTemplate both pass).

Follow-ups (not in this PR)

• Root-cause the templated crash from the Play pre-launch report; likely make the messaging surface a ListTemplate/SectionedItemTemplate of ConversationItems rather than a TabTemplate dashboard.
• The nodes/status dashboard is a better fit for a future generally-available IOT/POI templated app (separate investigation).

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Added support for an optional templated Android Auto experience in specific builds.
  • Improved build-time controls so the car experience can switch between notification-only and templated modes.

• Bug Fixes

  • Prevented Android Auto template errors from crashing the host by falling back safely when template generation fails.
  • Kept the car experience disabled by default for production builds.