Summary

tests/agent/test_memory_user_id.py::TestMemoryManagerUserIdThreading::test_multiple_providers_all_receive_user_id currently imports agent.builtin_memory_provider.BuiltinMemoryProvider, but that module/class does not exist in the repository.

The failure blocks the intended regression coverage for mixed built-in + external memory-provider initialization and also highlights code/docs drift around MemoryManager's "always-on built-in provider" story.

Affected files / lines

• tests/agent/test_memory_user_id.py:112-128
• agent/memory_manager.py:1-18, 71-129
• agent/memory_provider.py:3-14
• run_agent.py:1191-1218

Why this is a bug

The test suite claims to verify that both the built-in memory layer and an external provider receive threaded user_id, but the regression test cannot even import the built-in provider abstraction it expects.

This is more than a flaky test name mismatch:

• agent/memory_manager.py and agent/memory_provider.py still document an always-present BuiltinMemoryProvider
• run_agent.py now only instantiates MemoryManager when memory.provider is configured, and only adds the external plugin
• there is no agent/builtin_memory_provider.py implementation to exercise the documented path

So the code, docs, and tests are out of sync, and the regression coverage for this memory path is currently dead.

Minimal reproduction / evidence

Run:

source venv/bin/activate
pytest -q tests/agent/test_memory_user_id.py::TestMemoryManagerUserIdThreading::test_multiple_providers_all_receive_user_id -vv

Current failure:

E   ModuleNotFoundError: No module named 'agent.builtin_memory_provider'

Expected behavior

Either:

1. the built-in memory provider abstraction exists and the regression test can exercise it, or
2. the test/docs are updated to match the current architecture and coverage is restored through the real built-in memory path.

Actual behavior

The regression test imports a module that does not exist, so the intended user_id-threading coverage never runs.

Suggested investigation direction

• Decide whether BuiltinMemoryProvider is still a real architectural concept.
• If yes, restore the implementation/module and wire it through MemoryManager.
• If no, delete the stale abstraction from docs/comments/tests and replace this test with coverage against the actual built-in memory path that ships today.