fix: orchestrator button + Pi SDK session error

- Move leftSidebarMode from URL state to local useState in unified-shell,
    avoiding force-dynamic router round-trip that made the button appear broken                                           - Replace fileURLToPath(new URL(..., import.meta.url)) with process.cwd()
    in bb-pi-bootstrap.ts — import.meta.url is a webpack:// URL in Next.js,
    causing cross-realm TypeError when passed to Node.js fileURLToPath()

src/components/agents/hooks/use-agent-status.ts

@@ -0,0 +1,68 @@
+// src/components/agents/hooks/use-agent-status.ts
+import { useState, useEffect, useRef } from 'react';
+
+export type WorkerStatus = 'idle' | 'spawning' | 'working' | 'blocked' | 'completed' | 'failed';
+
+export interface AgentStatus {
+  agentTypeId?: string;
+  workerStatus: WorkerStatus;
+  workerDisplayName?: string;
+  workerError?: string;
+  isLoading: boolean;
+}
+
+const POLL_INTERVAL_MS = 5000;
+
+export function useAgentStatus(beadId: string): AgentStatus {
+  const [status, setStatus] = useState<AgentStatus>({
+    workerStatus: 'idle',
+    isLoading: true,
+  });
+  const intervalRef = useRef<NodeJS.Timeout | null>(null);
+
+  const fetchStatus = async () => {
+    if (!beadId) return;
+    
+    try {
+      const response = await fetch(`/api/runtime/worker-status?beadId=${encodeURIComponent(beadId)}`);
+      if (!response.ok) {
+        // If API returns 404 or error, no worker exists yet
+        setStatus({ workerStatus: 'idle', isLoading: false });
+        return;
+      }
+      
+      const data = await response.json();
+      setStatus({
+        workerStatus: data.status || 'idle',
+        workerDisplayName: data.displayName,
+        workerError: data.error,
+        agentTypeId: data.agentTypeId,
+        isLoading: false,
+      });
+    } catch (error) {
+      console.error('Failed to fetch worker status:', error);
+      setStatus({ workerStatus: 'idle', isLoading: false });
+    }
+  };
+
+  useEffect(() => {
+    if (!beadId) {
+      setStatus({ workerStatus: 'idle', isLoading: false });
+      return;
+    }
+
+    // Initial fetch
+    fetchStatus();
+
+    // Set up polling
+    intervalRef.current = setInterval(fetchStatus, POLL_INTERVAL_MS);
+
+    return () => {
+      if (intervalRef.current) {
+        clearInterval(intervalRef.current);
+      }
+    };
+  }, [beadId]);
+
+  return status;
+}