[moetemp]

What changed?

This PR maps the crate's stream_unsupported reason to a new StreamUnsupportedError, which is non-retryable and exported with the other Stream errors. The crate pin moves to s9 3984189f, where each Store declares its capabilities and a call that needs a missing one fails with that reason, code UNIMPLEMENTED, and the capability's name at the end of the message. MemoryStreamPlugin takes durable_writes, so a test can ask the memory Store for replicas it doesn't have.

Please note that a Workflow flush runs in Core's before_complete, so on the Workflow path a missing capability fails the Workflow Task with the capability's name, and Workflow code sees no exception. Activities and clients get StreamUnsupportedError.

Why?

A Store other than Redis may lack a feature, and the caller must learn which one by name.

How did you test it?

pytest tests/contrib/streams. The mapping test checks the error class, code and name. A live test runs MemoryStreamPlugin(durable_writes=1) and checks that the Workflow Task fails with replica_wait. test_vectors still matches the crate's protos and vectors. Full poe lint and the full suite pass at this layer, except test_envconfig, which reads a config file on this host.

• Unit Tests
• Staging
• End to End Tests

[moetemp]

Closing as stale. This layer is folded into the v5 tip, #365, and the upstream review uses a fresh series instead. Plan: https://www.notion.so/4048fc567738814990b7c796ac28fe3f