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0924755591
## Description
The Memory MCP server previously assigned its backend before
asynchronous embedder and vector-index warm-up completed. A tool call
arriving
during the handshake could therefore receive a partially initialized
backend.
Backend initialization is now atomic and shared between concurrent
callers. The backend is published only after warm-up succeeds. Failed
candidates are closed and discarded so later calls can retry with a
fresh backend.
## Type of Change
- [x] Bug fix
- [ ] New feature
- [ ] Breaking change
- [ ] Documentation-only change
- [ ] Refactoring
## Changes Made
- Keep the initializing backend local until warm-up completes
successfully.
- Share one initialization task between handshake and concurrent tool
calls.
- Await the shared task before exposing the backend to tool handlers.
- Shield shared initialization from cancellation by an individual tool
caller.
- Close failed or cancelled backend candidates.
- Clear failed initialization state so subsequent calls can retry.
- Retrieve and log background initialization failures.
- Add regression tests for handshake races, failure recovery, and
concurrent initialization.
- Add an Unreleased changelog entry.
## Testing
- [x] Added regression tests
- [x] Focused test suite passes
- [x] Ruff checks pass
- [x] Mypy passes
- [x] Changed files pass formatting checks
- [ ] Entire repository test suite passes without baseline failures
Commands and results:
- `uv run --extra dev --frozen pytest
tests/test_memory/test_mcp_server.py -q`
- `12 passed`
- `uv run --extra dev --frozen ruff check .`
- Passed
- `uv run --extra dev --frozen ruff format --check
headroom/memory/mcp_server.py tests/test_memory/test_mcp_server.py`
- Passed
- `uv run --extra dev --frozen mypy headroom --ignore-missing-imports`
- Success across 504 source files
- `uv run --extra dev --frozen pytest -q`
- `9363 passed, 565 skipped, 4 failed`
- The four failures are existing, unrelated failures outside the changed
code:
- `test_l2_appends_transform_label`
- `test_recovery_records_sockets_and_secures_both_backups`
- `test_dashboard_uses_cached_stats_and_lazy_history_feed_polling`
- `test_smart_crusher_log_fallback_runs_for_valid_json`
Repository-wide `ruff format --check .` also identifies pre-existing
formatting drift in the untouched
`headroom/proxy/handlers/anthropic.py`.
## Real Behavior Proof
The regression tests exercise the affected lifecycle directly:
1. Start backend initialization through the MCP handshake.
2. Suspend warm-up before it completes.
3. Issue a memory tool call and verify its handler is not invoked.
4. Release warm-up and verify the tool receives the initialized backend.
5. Force background initialization to fail and verify the candidate is
closed.
6. Issue another tool call and verify initialization retries with a
fresh backend.
7. Start two tool calls concurrently and verify only one backend is
constructed.
Observed behavior:
- Tool calls remain pending while handshake warm-up is incomplete.
- A partially initialized backend never reaches a tool handler.
- Failed candidates are closed and discarded.
- A later tool call successfully retries initialization.
- Concurrent calls share one initialization task and backend.
Environment: macOS arm64, CPython 3.12.13.
Not tested: a live stdio MCP client using the real ONNX model and
database. The affected initialization lifecycle is covered with
deterministic asynchronous regression tests.
## Review Readiness
- [x] I have performed a self-review before requesting human review.
- [x] This PR is ready for human review.
## Checklist
- [x] The implementation follows the repository’s existing style and
error-handling conventions.
- [x] Tests cover the reported race, concurrent initialization, and
failure recovery.
- [x] Failed initialization does not leave a partially published
backend.
- [x] Failed backend candidates are closed before retry.
- [x] No unrelated files or formatting changes are included.
- [x] No temporary logging, debug code, or commented-out code remains.
- [x] Public behavior changes are documented in the changelog.
- [x] The branch has been rebased from the intended base and is ready
for review.
## Additional Notes
The four full-suite failures listed above occur outside the changed
Memory MCP code and are unrelated to this PR. All tests covering the
modified initialization lifecycle pass.
---------
Co-authored-by: Tejas Chopra <chopratejas@gmail.com>
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|---|---|---|
| .. | ||
| __init__.py | ||
| conftest.py | ||
| test_budget.py | ||
| test_core_operations.py | ||
| test_easy.py | ||
| test_embedder_mps_serialization.py | ||
| test_embedder_thread_cap.py | ||
| test_extraction.py | ||
| test_factory.py | ||
| test_factory_embedder_cache.py | ||
| test_factory_external.py | ||
| test_hierarchical.py | ||
| test_hnsw_batch_capacity.py | ||
| test_learn_flag.py | ||
| test_local_backend_search.py | ||
| test_mcp_server.py | ||
| test_qdrant_env.py | ||
| test_query_conditions.py | ||
| test_skip_helpers.py | ||
| test_supersession_repair.py | ||
| test_traffic_learner.py | ||
| test_writers.py | ||