openhuman/docs/tinyagents-full-migration-plan/04-sessions/README.md

04 — Sessions & stores

Make tinyagents Store/AppendStore the durable session substrate and retire the legacy transcript stack. The Phase-1 write-only importer already exists (src/openhuman/session_import/, openhuman.session_import_run, design in ../../tinyagents-session-migration-design.md).

Target SDK surface: Store/FileStore, AppendStore/JsonlAppendStore, StoreRegistry on RunContext, ChatHistory/StoreChatHistory, SessionId/ThreadId/RunId, HarnessRunStatus.

Steps:

1. 01-live-writes.md — new turns write tinyagents records first.
2. 02-read-cutover.md — import phases 2–4: shadow reads, cutover, retire.
3. 03-checkpointer.md — SqliteCheckpointer swap (needs 00-baseline).

Done when: session/transcript.rs, session/migration.rs, session/turn/session_io.rs, and session_import/ are deleted; readers serve from tinyagents_store/; run inspection uses crate lineage ids.

CONSTRAINT (from importer work): store/stream names are slash-free — per-session streams are session.{stem}.messages.

Risk: transcript shape is user data — every cutover step keeps the legacy reader until parity fixtures (11-fixture matrix in the design doc) pass.