fix(pi): converge worker failures and thinking state

electron/coding-runtime/pi/extension-host.ts

@@ -158,6 +158,25 @@ export class PiManagedExtensionHost {
     this.productTools = productTools;
   }
 
+  getDiagnostics(): {
+    registrations: { parent: number; child: number };
+    writeLeases: { active: number; waiting: number };
+    bridgeRequests: number;
+  } {
+    const records = [...this.registrations.values()];
+    return {
+      registrations: {
+        parent: records.filter(({ role }) => role === 'parent').length,
+        child: records.filter(({ role }) => role === 'child').length,
+      },
+      writeLeases: {
+        active: records.reduce((total, { leases }) => total + leases.size, 0),
+        waiting: records.reduce((total, { waiters }) => total + waiters.size, 0),
+      },
+      bridgeRequests: this.requestFlights.size,
+    };
+  }
+
   async registerWorker(input: RegisterPiExtensionWorkerInput): Promise<PiExtensionWorkerRegistration> {
     if (!Number.isSafeInteger(input.generation) || input.generation <= 0) {
       throw new Error('Worker generation must be a positive safe integer');