## Why
Startup-only cleanup leaves expired logs in long-running sessions, and age-based retention alone does not limit database usage.
## What changed
Run cleanup in the background immediately after initialization and every 30 minutes. Start with the existing 10-day retention window, then halve it until occupied SQLite pages fit within a 64 MiB budget or the window reaches one second. Preserve logs within that final second even when they exceed the budget.
Exclude free pages from the budget so SQLite can reuse them, and retain the passive checkpoint after the first sweep. Stop the task when the runtime is dropped or the log pool is closed.
## Testing
Add tests for the 10-day boundary, repeated retention-window halving, free-page accounting, the one-second retention floor, immediate startup cleanup, and periodic cleanup without new writes or a restart. Update existing log tests to use current timestamps so background retention does not remove their fixtures.
GitOrigin-RevId: c6eeb5ec13006d4a03354e08322827429be53ce8
Dmitriy Kovalenko
8ea2c0e0d4