The session db fixture now disposes the engine before deleting the file, since a
module under a no-op db (tests/sdk, tests/flow) may have connected first; the
sdk import tests forget the study packages they import; the supervision tests
keep the real quarantine length so it cannot expire mid-assertion.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013GAeg4Jo6xjZzjwy9QDWMQ