[mikahatdichlieb]

Closes #12

What

Reads foreground app sessions from UsageStatsManager and keeps them in a local Room buffer, independent of the network. Nothing is uploaded yet; that is #13.

• Start at pairing: a successful pairing sets the starting point. Before that there is none, so nothing from before pairing is ever read.
• Hourly run: WorkManager runs collection every hour with no network constraint, because Android keeps raw usage events only for a few days. Each run reads the UsageEvents since the last run, builds sessions and stores the events together with the new starting point in one Room transaction.
• Sessions: a session ends on pause, when another app comes to the front, screen off, keyguard or shutdown. A pause and resume of the same app within 2 seconds (switching its own activities) stays one session. A session still running at the end of a run is finished in a later run.
• Events: Unix-second start_ts, duration_secs up to 86400 (longer sessions are split, under 1 s dropped), package name as app_id. No label, no domain, never a category. The event_id is a hash of app and start time, so re-reading a window never duplicates anything locally or on the server.
• Filters: this app itself and the current launcher are skipped.
• Without usage access the run does nothing. The permission screen comes with Usage access permission screen #14.
• Re-pairing needed: collection keeps running while the device waits to be paired again.
• Clock set back: collection waits until the clock passes the last stored point again.

Security / privacy relevant

• The manifest declares PACKAGE_USAGE_STATS (a special access the user grants in the settings) and a <queries> entry for the HOME intent, used only to find the launcher.
• Stored per event: package name, start time and duration. The buffer lives in the app database, which is excluded from backups. There is no size cap on the buffer.

Dependencies

Room 2.8.5, WorkManager 2.12.0 and KSP 2.3.12, each more than two weeks old. Most of the new verification-metadata entries are compile-time tooling for the Room compiler (Guava, kotlinpoet, sqlite-jdbc). The release runtime classpath gains only androidx modules (Room, SQLite, WorkManager, Lifecycle parts), and contains nothing from Play Services or Firebase. All CI tasks pass one at a time with a cold GRADLE_USER_HOME. The Room schema is committed under app/schemas/.

Tests

UsageSessionsTest, SessionEventsTest and UsageCollectorTest (against a fake DAO). The Room DAO itself and the Android side have not been exercised on a device yet: UsageEvents types, launcher detection and the WorkManager schedule are all untested.