Agno v3.1.8 adds Postgres sandbox checkpoint store and changes default checkpoint retention

The new PostgresCheckpointStore saves sandbox checkpoints in PostgreSQL, so multi-replica deployments can restore sessions without S3 or a shared filesystem. Checkpoints are chunked, written transactionally, deduplicated by SHA-256 and verified on read. It is opt-in, and existing checkpoint defaults are unchanged.

Sandboxes now keep the three newest checkpoints per session by default, and older ones are deleted after the run outcome is stored. Setting retain_checkpoints=None restores unlimited retention. Opening a checkpoint for an older run can now raise CheckpointObjectNotFound.

Deleting a sandbox-backed session also removes its warm computer and checkpoint objects after the database transaction commits. AgentOS now fails at startup if a durable-queue sandbox uses the host-local default checkpoint store. Claude() now defaults to claude-sonnet-5-5 in place of the retiring claude-sonnet-4-5-20250929.

If you run sandboxes across several replicas, you can now use PostgreSQL for checkpoints instead of S3 or shared storage.

Code that opens checkpoints from older runs may now hit CheckpointObjectNotFound unless you set retain_checkpoints=None.

Agents that rely on the default Claude model will move to claude-sonnet-5-5, and non-default temperature, top_p and top_k values are dropped for newer Claude models.