Ensure store server serializes access per thread

[Yuge Zhang (ultmaster)]

Summary

• document that the loop-aware async lock is intentionally thread-unsafe while simplifying its per-event-loop bookkeeping
• guard every LightningStoreServer delegate method with a server-level threading lock and route requests through those methods to keep access serialized within the server process

Testing

• uv run pyright
• uv run pytest tests/store/test_memory.py::test_store_lock_rebinds_to_new_event_loop
• uv run pytest tests/store/test_client_server.py

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https://chatgpt.com/codex/tasks/task_e_68f592757158832ea4368388b2b64c79

[Copilot]

Pull Request Overview

Adds an event-loop–aware async lock to the in‑memory store and serializes server delegate access with a server-level lock, updating API routes to funnel through wrapped methods.

• Introduces _LoopAwareAsyncLock to allow reusing the in‑memory store across different event loops (thread-unsafe by design).
• Wraps LightningStoreServer delegate calls with a new locking layer and routes FastAPI endpoints through the server methods.
• Adds a test to verify store usability after switching to a new event loop.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
tests/store/test_memory.py	Adds test ensuring the in-memory store lock rebinds correctly when used from a new event loop.
agentlightning/store/memory.py	Implements _LoopAwareAsyncLock and replaces prior asyncio.Lock usage in the store.
agentlightning/store/client_server.py	Adds per-server lock and routes HTTP handlers through serialized delegate methods.

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[Copilot]

Using a blocking threading.Lock inside an async code path will block the entire event loop when contention occurs (another request waiting to acquire the lock will hard-block the loop), defeating concurrency and risking stalls. Replace threading.Lock with an asyncio.Lock (initialized as self._lock = asyncio.Lock()) and use async with self._lock: so awaiting the method does not block other tasks from running while they wait for the lock.

Suggested change

	with self._lock:
	async with self._lock:

[Yuge Zhang (ultmaster)]

This change is intentional to make _call_store_method thread-safe.