Clean up orphaned locks on session creation failure

Clarify getOrCreateSession JSDoc to explain why callers must hold the
session lock. Add cleanup of sessionLocks when session creation fails
to prevent minor memory leaks.

Author: ghostwriternr

packages/sandbox-container/src/services/session-manager.ts

@@ -47,10 +47,12 @@ export class SessionManager {
    *
    * Uses a two-phase approach:
    * 1. Check if session exists (fast path)
-   * 2. Use creatingLocks map with atomic check-and-set to coordinate creation
+   * 2. Use creatingLocks map to coordinate creation across callers
    *
-   * IMPORTANT: This method must be called while holding the session lock
-   * to prevent race conditions between checking and setting creatingLocks.
+   * IMPORTANT: All callers (executeInSession, withSession, etc.) acquire the
+   * session lock before calling this method. The lock ensures only one caller
+   * executes this method at a time for a given sessionId, making the
+   * creatingLocks check-and-set atomic.
    */
   private async getOrCreateSession(
     sessionId: string,
@@ -125,6 +127,10 @@ export class SessionManager {
       };
     } finally {
       this.creatingLocks.delete(sessionId);
+      // Clean up orphaned lock if session creation failed
+      if (!this.sessions.has(sessionId)) {
+        this.sessionLocks.delete(sessionId);
+      }
     }
   }