feat(web): add agent output terminal tabs for orchestrator sessions (CT-ORCH-002)

Implements read-only agent output viewing in the TerminalPanel as a
separate tab group alongside interactive PTY terminal sessions.

- useAgentStream hook: SSE connection to /api/orchestrator/events with
  exponential backoff reconnect, per-agent output accumulation, and
  full lifecycle tracking (spawning→running→completed/error)
- AgentTerminal component: read-only <pre>-based output view with ANSI
  stripping, status indicator (pulse/dot), status badge, elapsed duration,
  copy-to-clipboard, and error message overlay
- TerminalPanel integration: agent tabs appear automatically when agents
  are active, show colored status dots, dismissable when completed/error,
  and section divider separates terminal vs agent tabs
- 79 new unit tests across useAgentStream, AgentTerminal, and TerminalPanel

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/components/terminal/TerminalPanel.test.tsx

@@ -33,6 +33,20 @@ vi.mock("./XTerminal", () => ({
   ),
 }));
 
+// Mock AgentTerminal to avoid complexity in panel tests
+vi.mock("./AgentTerminal", () => ({
+  AgentTerminal: vi.fn(
+    ({ agent }: { agent: { agentId: string; agentType: string; status: string } }) => (
+      <div
+        data-testid="mock-agent-terminal"
+        data-agent-id={agent.agentId}
+        data-agent-type={agent.agentType}
+        data-status={agent.status}
+      />
+    )
+  ),
+}));
+
 // Mock useTerminalSessions
 const mockCreateSession = vi.fn();
 const mockCloseSession = vi.fn();
@@ -72,6 +86,29 @@ vi.mock("@/hooks/useTerminalSessions", () => ({
   })),
 }));
 
+// Mock useAgentStream
+const mockDismissAgent = vi.fn();
+let mockAgents = new Map<
+  string,
+  {
+    agentId: string;
+    agentType: string;
+    status: "spawning" | "running" | "completed" | "error";
+    outputLines: string[];
+    startedAt: number;
+  }
+>();
+let mockAgentStreamConnected = false;
+
+vi.mock("@/hooks/useAgentStream", () => ({
+  useAgentStream: vi.fn(() => ({
+    agents: mockAgents,
+    isConnected: mockAgentStreamConnected,
+    connectionError: null,
+    dismissAgent: mockDismissAgent,
+  })),
+}));
+
 import { TerminalPanel } from "./TerminalPanel";
 
 // ==========================================
@@ -100,6 +137,8 @@ describe("TerminalPanel", () => {
     mockIsConnected = false;
     mockConnectionError = null;
     mockRegisterOutputCallback.mockReturnValue(vi.fn());
+    mockAgents = new Map();
+    mockAgentStreamConnected = false;
   });
 
   // ==========================================
@@ -425,4 +464,118 @@ describe("TerminalPanel", () => {
       expect(mockCreateSession).not.toHaveBeenCalled();
     });
   });
+
+  // ==========================================
+  // Agent tab integration
+  // ==========================================
+
+  describe("agent tab integration", () => {
+    function setOneAgent(status: "spawning" | "running" | "completed" | "error" = "running"): void {
+      mockAgents = new Map([
+        [
+          "agent-1",
+          {
+            agentId: "agent-1",
+            agentType: "worker",
+            status,
+            outputLines: ["Hello from agent\n"],
+            startedAt: Date.now() - 3000,
+          },
+        ],
+      ]);
+    }
+
+    it("renders an agent tab when an agent is active", () => {
+      setOneAgent("running");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(screen.getAllByTestId("agent-tab")).toHaveLength(1);
+    });
+
+    it("renders no agent tabs when agents map is empty", () => {
+      mockAgents = new Map();
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(screen.queryByTestId("agent-tab")).not.toBeInTheDocument();
+    });
+
+    it("agent tab button has the agent type as label", () => {
+      setOneAgent("running");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(screen.getByRole("tab", { name: "Agent: worker" })).toBeInTheDocument();
+    });
+
+    it("agent tab has role=tab", () => {
+      setOneAgent("running");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(screen.getByRole("tab", { name: "Agent: worker" })).toBeInTheDocument();
+    });
+
+    it("shows dismiss button for completed agents", () => {
+      setOneAgent("completed");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(screen.getByRole("button", { name: "Dismiss worker agent" })).toBeInTheDocument();
+    });
+
+    it("shows dismiss button for error agents", () => {
+      setOneAgent("error");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(screen.getByRole("button", { name: "Dismiss worker agent" })).toBeInTheDocument();
+    });
+
+    it("does not show dismiss button for running agents", () => {
+      setOneAgent("running");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(
+        screen.queryByRole("button", { name: "Dismiss worker agent" })
+      ).not.toBeInTheDocument();
+    });
+
+    it("does not show dismiss button for spawning agents", () => {
+      setOneAgent("spawning");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(
+        screen.queryByRole("button", { name: "Dismiss worker agent" })
+      ).not.toBeInTheDocument();
+    });
+
+    it("calls dismissAgent when dismiss button is clicked", () => {
+      setOneAgent("completed");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      fireEvent.click(screen.getByRole("button", { name: "Dismiss worker agent" }));
+      expect(mockDismissAgent).toHaveBeenCalledWith("agent-1");
+    });
+
+    it("renders AgentTerminal when agent tab is active", () => {
+      setOneAgent("running");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      // Click the agent tab to make it active
+      fireEvent.click(screen.getByRole("tab", { name: "Agent: worker" }));
+      // AgentTerminal should be rendered (mock shows mock-agent-terminal)
+      expect(screen.getByTestId("mock-agent-terminal")).toBeInTheDocument();
+    });
+
+    it("shows a divider between terminal and agent tabs", () => {
+      setTwoSessions();
+      setOneAgent("running");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      // The divider div is aria-hidden; check it's present in the DOM
+      const tablist = screen.getByRole("tablist");
+      const divider = tablist.querySelector('[aria-hidden="true"][style*="width: 1"]');
+      expect(divider).toBeInTheDocument();
+    });
+
+    it("agent tabs show correct data-agent-status", () => {
+      setOneAgent("running");
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      const tab = screen.getByTestId("agent-tab");
+      expect(tab).toHaveAttribute("data-agent-status", "running");
+    });
+
+    it("empty state not shown when agents exist but no terminal sessions", () => {
+      mockSessions = new Map();
+      setOneAgent("running");
+      mockIsConnected = false;
+      render((<TerminalPanel open={true} onClose={onClose} token="test-token" />) as ReactElement);
+      expect(screen.queryByText("Connecting...")).not.toBeInTheDocument();
+    });
+  });
 });