OpenAI Agents SDK — GA resume contract

The 2026-04-16 GA release of openai-agents generalised the preview Session protocol into three cooperating interfaces:

• SessionStore — per-turn conversation items.
• SnapshotStore — durable RunState + SandboxSessionState blobs.
• ResumeProvider — locator layer for picking a SnapshotRef to resume from.

Mnemo ships adapters for both halves.

MnemoSessionStore (chat history)

python/mnemo/openai_sessions.py. Stores each conversation turn as a session-tagged episodic memory; survives process restarts.

from mnemo.openai_sessions import MnemoSessionStore

session = MnemoSessionStore(
    db_path="agent.mnemo.db",
    agent_id="user-42",
    session_id="support-2026-04-20",
)
# Pass `session=session` to the Agents SDK `Runner`.

MnemoSnapshotStore (run state)

python/mnemo/openai_sessions_ga.py. Persists RunState + SandboxSessionState and lets the GA SDK resume crashed runs.

from mnemo.openai_sessions_ga import MnemoSnapshotStore

store = MnemoSnapshotStore(
    session_id="support-2026-04-20",
    db_path="agent.mnemo.db",
    agent_id="user-42",
    workspace_backend="local",
    workspace_root="/var/mnemo/snapshots",
)

ref = await store.save_snapshot(run_state, sandbox_state)
# ... process crashes ...
ref, run, sandbox = await store.resume(from_ref="latest")

SnapshotRef.as_uri() returns a stable snapshot://<session>/<ts> URI suitable for the forthcoming MCP resource exposure layer.

Payload storage policy

• Inline — payloads at or below inline_threshold_bytes (default 64 KiB) live in the Mnemo memory body as base64, with a SHA-256 digest.
• Offload — larger payloads go to a pluggable WorkspaceStorage. Mnemo only keeps the locator + SHA-256; the load_snapshot path verifies the digest on every read.

Workspace backends

• local — shipped. Writes under workspace_root.
• s3 / r2 / gcs / azure — stubs in v0.3.1. The WorkspaceStorage class raises NotImplementedError with a NotImplementedError("…install mnemo[openai-sandbox-<backend>] …") message. The v0.3.1 roadmap ships a real aioboto3-backed S3 backend; R2/GCS/Azure follow once the SnapshotSpec shape stabilises in the GA SDK.

Install with pip install mnemo[openai-agents].

Example (crash / resume)

See python/examples/openai_agents_snapshot_example.py for a 3-step agent that writes two snapshots, crashes before the final reply, and resumes from the latest snapshot on the second process start. The equivalent openai_agents_resume_s3_example.py ships with the v0.3.1 S3 backend.