DL-089

The agent persists nothing DURABLE: the injected backend is a TEE — it reads and writes the container-local EPHEMERAL session file normally (so the SDK’s own loader, compaction, and rewrites work) and tees each committed write upstream as a durable TranscriptEntry frame (append→delta, writeFull→checkpoint, awaited per-path for per-session send order; agent-stamped per-lifetime entry_seq, server-rebased to session scope). Zero S3 credentials, zero storage detail; the local file dies with the container. A definitively-erred emit buffers under a bounded cap with escalating warn→error retry and FAILS THE SESSION at cap exhaustion (resumable from the last committed prefix; cap value is tuning, not freeze-scope)

Status: Active (Matt, 2026-07-31)

Record: ../../agent/compass-agent-session-persistence/design.md#the-sdk-seam-grounded-revised-for-the-tee