fix(pi): strengthen final release proof

electron/coding-runtime/pi/subagent.ts

@@ -98,6 +98,9 @@ class FifoSemaphore {
     }
   }
 
+  get activeCount(): number { return this.active; }
+  get waitingCount(): number { return this.waiters.length; }
+
   acquire(signal: AbortSignal): Promise<() => void> {
     if (signal.aborted) return Promise.reject(new PiSubagentChildError('SUBAGENT_ABORTED'));
     if (this.active < this.maximum) return Promise.resolve(this.issuePermit());
@@ -292,6 +295,20 @@ export class PiSubagentScheduler {
     }
   }
 
+  getDiagnostics(): {
+    activeChildPermits: number;
+    waitingChildPermits: number;
+    activeDispatches: number;
+    activeParents: number;
+  } {
+    return {
+      activeChildPermits: this.childPermits.activeCount,
+      waitingChildPermits: this.childPermits.waitingCount,
+      activeDispatches: this.dispatches.size,
+      activeParents: this.parentDispatches.size,
+    };
+  }
+
   async close(): Promise<void> {
     if (this.closing) {
       await Promise.allSettled([...this.dispatches.values()].map((record) => record.flight));