pyamber's worker-to-worker RPC proxy has no production callers #7793

Describe the bug

AsyncRPCClient.get_worker_interface in amber/src/main/python/core/architecture/rpc/async_rpc_client.py has no production callers, and it is the sole route into a whole helper that exists only to serve it.

Evidence (repo-wide, excluding target/, .git/, node_modules/, and the generated src/main/python/proto/):

grep -rn "get_worker_interface" .
→ async_rpc_client.py (definition)
→ test_async_rpc_client.py x3   (the only call sites)

grep -rn "WorkerServiceStub" .
→ async_rpc_client.py only — the import, the return annotation, one argument. No .scala hit.

grep -rn "_create_proxy" .
→ its definition, and one call inside get_worker_interface — its sole caller

Python workers talk only to the coordinator: the one production construction of the Python AsyncRPCClient is main_loop.py:114, and it uses coordinator_stub() (lines 271, 651, 671, 817) and receive (line 475). There is no getattr-style dynamic access anywhere. Worker-to-worker RPC initiated from Python is unused.

Note Scala's workerInterface (AsyncRPCClient.scala:140, WorkerServiceFs2Grpc) is a separate class and is unrelated to this Python method.

The three tests that reference it — test_stream_unary_blocked, test_unary_stream_blocked, test_stream_stream_blocked — each begin by calling get_worker_interface and then assert on blockers that live only inside _create_proxy's local Proxy class. They exist solely to exercise this method. The coordinator path goes through _assign_context, never had those blockers, and has its own tests.

How to reproduce?

Run the greps above.

Version/Branch

main

Task Type

• Refactor / Cleanup
• DevOps / Deployment / CI
• Testing / QA
• Documentation
• Performance
• Other