Race condition in concurrent indexing requests

[Retengart]

Problem

Check for existing indexing and setting indexing state is not atomic.

Current Behavior

// handlers.ts:192-200
if (this.snapshotManager.getIndexingCodebases().includes(absolutePath)) {
    return { /* already indexing */ };
}
// ... validation code ...
this.snapshotManager.setCodebaseIndexing(absolutePath, 0);

Gap between check and set allows race condition.

Impact

Two concurrent index requests for same path may both pass the check and start parallel indexing jobs.

Expected Behavior

Atomic check-and-set, or use mutex/lock for indexing operations.

Location

• packages/mcp/src/handlers.ts:192-282