From 61522f43aa02b550c1db4149fc9e85efe84b9919 Mon Sep 17 00:00:00 2001
From: Jason Woltje <jason@diversecanvas.com>
Date: Wed, 25 Feb 2026 22:00:27 -0600
Subject: [PATCH] feat(web): add agent output terminal tabs for orchestrator
 sessions (CT-ORCH-002)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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>
---
 .../terminal/AgentTerminal.test.tsx           | 368 ++++++++++++
 .../src/components/terminal/AgentTerminal.tsx | 381 ++++++++++++
 .../terminal/TerminalPanel.test.tsx           | 153 +++++
 .../src/components/terminal/TerminalPanel.tsx | 236 +++++++-
 apps/web/src/components/terminal/index.ts     |   2 +
 .../hooks/__tests__/useAgentStream.test.ts    | 542 ++++++++++++++++++
 apps/web/src/hooks/useAgentStream.ts          | 319 +++++++++++
 7 files changed, 1991 insertions(+), 10 deletions(-)
 create mode 100644 apps/web/src/components/terminal/AgentTerminal.test.tsx
 create mode 100644 apps/web/src/components/terminal/AgentTerminal.tsx
 create mode 100644 apps/web/src/hooks/__tests__/useAgentStream.test.ts
 create mode 100644 apps/web/src/hooks/useAgentStream.ts

diff --git a/apps/web/src/components/terminal/AgentTerminal.test.tsx b/apps/web/src/components/terminal/AgentTerminal.test.tsx
new file mode 100644
index 0000000..cf13b67
--- /dev/null
+++ b/apps/web/src/components/terminal/AgentTerminal.test.tsx
@@ -0,0 +1,368 @@
+/**
+ * @file AgentTerminal.test.tsx
+ * @description Unit tests for the AgentTerminal component
+ *
+ * Tests cover:
+ * - Output rendering
+ * - Status display (status indicator + badge)
+ * - ANSI stripping
+ * - Agent header information (type, duration, jobId)
+ * - Auto-scroll behavior
+ * - Copy-to-clipboard
+ * - Error message display
+ * - Empty state rendering
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { render, screen, fireEvent, act } from "@testing-library/react";
+import type { ReactElement } from "react";
+import { AgentTerminal } from "./AgentTerminal";
+import type { AgentSession } from "@/hooks/useAgentStream";
+
+// ==========================================
+// Mock navigator.clipboard
+// ==========================================
+
+const mockWriteText = vi.fn(() => Promise.resolve());
+Object.defineProperty(navigator, "clipboard", {
+  value: { writeText: mockWriteText },
+  writable: true,
+  configurable: true,
+});
+
+// ==========================================
+// Factory helpers
+// ==========================================
+
+function makeAgent(overrides: Partial<AgentSession> = {}): AgentSession {
+  return {
+    agentId: "test-agent-1",
+    agentType: "worker",
+    status: "running",
+    outputLines: [],
+    startedAt: Date.now() - 5000, // 5s ago
+    ...overrides,
+  };
+}
+
+// ==========================================
+// Tests
+// ==========================================
+
+describe("AgentTerminal", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.useFakeTimers({ shouldAdvanceTime: false });
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  // ==========================================
+  // Rendering
+  // ==========================================
+
+  describe("rendering", () => {
+    it("renders the agent terminal container", () => {
+      render((<AgentTerminal agent={makeAgent()} />) as ReactElement);
+      expect(screen.getByTestId("agent-terminal")).toBeInTheDocument();
+    });
+
+    it("has region role with agent type label", () => {
+      render((<AgentTerminal agent={makeAgent({ agentType: "planner" })} />) as ReactElement);
+      expect(screen.getByRole("region", { name: "Agent output: planner" })).toBeInTheDocument();
+    });
+
+    it("sets data-agent-id attribute", () => {
+      render((<AgentTerminal agent={makeAgent({ agentId: "my-agent-123" })} />) as ReactElement);
+      const container = screen.getByTestId("agent-terminal");
+      expect(container).toHaveAttribute("data-agent-id", "my-agent-123");
+    });
+
+    it("applies className prop to the outer container", () => {
+      render((<AgentTerminal agent={makeAgent()} className="custom-cls" />) as ReactElement);
+      expect(screen.getByTestId("agent-terminal")).toHaveClass("custom-cls");
+    });
+  });
+
+  // ==========================================
+  // Header
+  // ==========================================
+
+  describe("header", () => {
+    it("renders the agent type label", () => {
+      render((<AgentTerminal agent={makeAgent({ agentType: "coordinator" })} />) as ReactElement);
+      expect(screen.getByTestId("agent-type-label")).toHaveTextContent("coordinator");
+    });
+
+    it("includes jobId in the label when provided", () => {
+      render(
+        (
+          <AgentTerminal agent={makeAgent({ agentType: "worker", jobId: "job-42" })} />
+        ) as ReactElement
+      );
+      expect(screen.getByTestId("agent-type-label")).toHaveTextContent("worker · job-42");
+    });
+
+    it("does not show jobId separator when jobId is absent", () => {
+      render((<AgentTerminal agent={makeAgent({ agentType: "worker" })} />) as ReactElement);
+      expect(screen.getByTestId("agent-type-label")).not.toHaveTextContent("·");
+    });
+
+    it("renders the duration element", () => {
+      render((<AgentTerminal agent={makeAgent()} />) as ReactElement);
+      expect(screen.getByTestId("agent-duration")).toBeInTheDocument();
+    });
+
+    it("shows seconds for short-running agents", () => {
+      const agent = makeAgent({ startedAt: Date.now() - 8000 });
+      render((<AgentTerminal agent={agent} />) as ReactElement);
+      expect(screen.getByTestId("agent-duration")).toHaveTextContent("s");
+    });
+
+    it("shows minutes for long-running agents", () => {
+      const agent = makeAgent({ startedAt: Date.now() - 125000 }); // 2m 5s
+      render((<AgentTerminal agent={agent} />) as ReactElement);
+      expect(screen.getByTestId("agent-duration")).toHaveTextContent("m");
+    });
+  });
+
+  // ==========================================
+  // Status indicator
+  // ==========================================
+
+  describe("status indicator", () => {
+    it("shows a running indicator for running status", () => {
+      render((<AgentTerminal agent={makeAgent({ status: "running" })} />) as ReactElement);
+      const indicator = screen.getByTestId("status-indicator");
+      expect(indicator).toHaveAttribute("data-status", "running");
+    });
+
+    it("shows a spawning indicator for spawning status", () => {
+      render((<AgentTerminal agent={makeAgent({ status: "spawning" })} />) as ReactElement);
+      const indicator = screen.getByTestId("status-indicator");
+      expect(indicator).toHaveAttribute("data-status", "spawning");
+    });
+
+    it("shows completed indicator for completed status", () => {
+      render(
+        (
+          <AgentTerminal agent={makeAgent({ status: "completed", endedAt: Date.now() })} />
+        ) as ReactElement
+      );
+      const indicator = screen.getByTestId("status-indicator");
+      expect(indicator).toHaveAttribute("data-status", "completed");
+    });
+
+    it("shows error indicator for error status", () => {
+      render(
+        (
+          <AgentTerminal agent={makeAgent({ status: "error", endedAt: Date.now() })} />
+        ) as ReactElement
+      );
+      const indicator = screen.getByTestId("status-indicator");
+      expect(indicator).toHaveAttribute("data-status", "error");
+    });
+  });
+
+  // ==========================================
+  // Status badge
+  // ==========================================
+
+  describe("status badge", () => {
+    it("renders the status badge", () => {
+      render((<AgentTerminal agent={makeAgent({ status: "running" })} />) as ReactElement);
+      expect(screen.getByTestId("status-badge")).toHaveTextContent("running");
+    });
+
+    it("shows 'spawning' badge for spawning status", () => {
+      render((<AgentTerminal agent={makeAgent({ status: "spawning" })} />) as ReactElement);
+      expect(screen.getByTestId("status-badge")).toHaveTextContent("spawning");
+    });
+
+    it("shows 'completed' badge for completed status", () => {
+      render(
+        (
+          <AgentTerminal agent={makeAgent({ status: "completed", endedAt: Date.now() })} />
+        ) as ReactElement
+      );
+      expect(screen.getByTestId("status-badge")).toHaveTextContent("completed");
+    });
+
+    it("shows 'error' badge for error status", () => {
+      render(
+        (
+          <AgentTerminal agent={makeAgent({ status: "error", endedAt: Date.now() })} />
+        ) as ReactElement
+      );
+      expect(screen.getByTestId("status-badge")).toHaveTextContent("error");
+    });
+  });
+
+  // ==========================================
+  // Output rendering
+  // ==========================================
+
+  describe("output area", () => {
+    it("renders the output pre element", () => {
+      render((<AgentTerminal agent={makeAgent()} />) as ReactElement);
+      expect(screen.getByTestId("agent-output")).toBeInTheDocument();
+    });
+
+    it("shows 'Waiting for output...' when outputLines is empty and status is running", () => {
+      render(
+        (
+          <AgentTerminal agent={makeAgent({ status: "running", outputLines: [] })} />
+        ) as ReactElement
+      );
+      expect(screen.getByTestId("agent-output")).toHaveTextContent("Waiting for output...");
+    });
+
+    it("shows 'Spawning agent...' when status is spawning and no output", () => {
+      render(
+        (
+          <AgentTerminal agent={makeAgent({ status: "spawning", outputLines: [] })} />
+        ) as ReactElement
+      );
+      expect(screen.getByTestId("agent-output")).toHaveTextContent("Spawning agent...");
+    });
+
+    it("renders output lines as text content", () => {
+      const agent = makeAgent({
+        outputLines: ["Hello world\n", "Second line\n"],
+      });
+      render((<AgentTerminal agent={agent} />) as ReactElement);
+      const output = screen.getByTestId("agent-output");
+      expect(output).toHaveTextContent("Hello world");
+      expect(output).toHaveTextContent("Second line");
+    });
+
+    it("strips ANSI escape codes from output", () => {
+      const agent = makeAgent({
+        outputLines: ["\x1b[32mGreen text\x1b[0m\n"],
+      });
+      render((<AgentTerminal agent={agent} />) as ReactElement);
+      const output = screen.getByTestId("agent-output");
+      expect(output).toHaveTextContent("Green text");
+      expect(output.textContent).not.toContain("\x1b");
+    });
+
+    it("has aria-live=polite for screen reader announcements", () => {
+      render((<AgentTerminal agent={makeAgent()} />) as ReactElement);
+      expect(screen.getByTestId("agent-output")).toHaveAttribute("aria-live", "polite");
+    });
+  });
+
+  // ==========================================
+  // Error message
+  // ==========================================
+
+  describe("error message", () => {
+    it("shows error message when status is error and errorMessage is set", () => {
+      const agent = makeAgent({
+        status: "error",
+        endedAt: Date.now(),
+        errorMessage: "Process crashed",
+      });
+      render((<AgentTerminal agent={agent} />) as ReactElement);
+      expect(screen.getByTestId("agent-error-message")).toHaveTextContent("Process crashed");
+    });
+
+    it("renders alert role for error message", () => {
+      const agent = makeAgent({
+        status: "error",
+        endedAt: Date.now(),
+        errorMessage: "OOM killed",
+      });
+      render((<AgentTerminal agent={agent} />) as ReactElement);
+      expect(screen.getByRole("alert")).toBeInTheDocument();
+    });
+
+    it("does not show error message when status is running", () => {
+      render((<AgentTerminal agent={makeAgent({ status: "running" })} />) as ReactElement);
+      expect(screen.queryByTestId("agent-error-message")).not.toBeInTheDocument();
+    });
+
+    it("does not show error message when status is error but errorMessage is absent", () => {
+      const agent = makeAgent({ status: "error", endedAt: Date.now() });
+      render((<AgentTerminal agent={agent} />) as ReactElement);
+      expect(screen.queryByTestId("agent-error-message")).not.toBeInTheDocument();
+    });
+  });
+
+  // ==========================================
+  // Copy to clipboard
+  // ==========================================
+
+  describe("copy to clipboard", () => {
+    it("renders the copy button", () => {
+      render((<AgentTerminal agent={makeAgent()} />) as ReactElement);
+      expect(screen.getByTestId("copy-button")).toBeInTheDocument();
+    });
+
+    it("copy button has aria-label='Copy agent output'", () => {
+      render((<AgentTerminal agent={makeAgent()} />) as ReactElement);
+      expect(screen.getByRole("button", { name: "Copy agent output" })).toBeInTheDocument();
+    });
+
+    it("calls clipboard.writeText with stripped output on click", async () => {
+      const agent = makeAgent({
+        outputLines: ["\x1b[32mLine 1\x1b[0m\n", "Line 2\n"],
+      });
+      render((<AgentTerminal agent={agent} />) as ReactElement);
+
+      await act(async () => {
+        fireEvent.click(screen.getByTestId("copy-button"));
+        await Promise.resolve();
+      });
+
+      expect(mockWriteText).toHaveBeenCalledWith("Line 1\nLine 2\n");
+    });
+
+    it("shows 'copied' text briefly after clicking copy", async () => {
+      render((<AgentTerminal agent={makeAgent()} />) as ReactElement);
+
+      await act(async () => {
+        fireEvent.click(screen.getByTestId("copy-button"));
+        await Promise.resolve();
+      });
+
+      expect(screen.getByTestId("copy-button")).toHaveTextContent("copied");
+    });
+
+    it("reverts copy button text after timeout", async () => {
+      render((<AgentTerminal agent={makeAgent()} />) as ReactElement);
+
+      await act(async () => {
+        fireEvent.click(screen.getByTestId("copy-button"));
+        await Promise.resolve();
+      });
+
+      act(() => {
+        vi.advanceTimersByTime(2500);
+      });
+
+      expect(screen.getByTestId("copy-button")).toHaveTextContent("copy");
+    });
+  });
+
+  // ==========================================
+  // Auto-scroll
+  // ==========================================
+
+  describe("auto-scroll", () => {
+    it("does not throw when outputLines changes", () => {
+      const agent = makeAgent({ outputLines: ["Line 1\n"] });
+      const { rerender } = render((<AgentTerminal agent={agent} />) as ReactElement);
+
+      expect(() => {
+        rerender(
+          (
+            <AgentTerminal agent={{ ...agent, outputLines: ["Line 1\n", "Line 2\n"] }} />
+          ) as ReactElement
+        );
+      }).not.toThrow();
+    });
+  });
+});
diff --git a/apps/web/src/components/terminal/AgentTerminal.tsx b/apps/web/src/components/terminal/AgentTerminal.tsx
new file mode 100644
index 0000000..a647d5a
--- /dev/null
+++ b/apps/web/src/components/terminal/AgentTerminal.tsx
@@ -0,0 +1,381 @@
+"use client";
+
+/**
+ * AgentTerminal component
+ *
+ * Read-only terminal view for displaying orchestrator agent output.
+ * Uses a <pre> element with monospace font rather than xterm.js because
+ * this is read-only agent stdout/stderr, not an interactive PTY.
+ *
+ * Features:
+ * - Displays accumulated output lines with basic ANSI color rendering
+ * - Status badge (spinning/checkmark/X) indicating agent lifecycle
+ * - Header bar with agent type, status, and elapsed duration
+ * - Auto-scrolls to bottom as new output arrives
+ * - Copy-to-clipboard button for full output
+ */
+
+import { useEffect, useRef, useState, useCallback } from "react";
+import type { ReactElement, CSSProperties } from "react";
+import type { AgentSession, AgentStatus } from "@/hooks/useAgentStream";
+
+// ==========================================
+// Types
+// ==========================================
+
+export interface AgentTerminalProps {
+  /** The agent session to display */
+  agent: AgentSession;
+  /** Optional CSS class name for the outer container */
+  className?: string;
+  /** Optional inline style for the outer container */
+  style?: CSSProperties;
+}
+
+// ==========================================
+// ANSI color strip helper
+// ==========================================
+
+// Simple ANSI escape sequence stripper — produces readable plain text for <pre>.
+// We strip rather than parse for security and simplicity in read-only display.
+// eslint-disable-next-line no-control-regex
+const ANSI_PATTERN = /\x1b\[[0-9;]*[mGKHF]/g;
+
+function stripAnsi(text: string): string {
+  return text.replace(ANSI_PATTERN, "");
+}
+
+// ==========================================
+// Duration helper
+// ==========================================
+
+function formatDuration(startedAt: number, endedAt?: number): string {
+  const elapsed = Math.floor(((endedAt ?? Date.now()) - startedAt) / 1000);
+  if (elapsed < 60) return `${elapsed.toString()}s`;
+  const minutes = Math.floor(elapsed / 60);
+  const seconds = elapsed % 60;
+  return `${minutes.toString()}m ${seconds.toString()}s`;
+}
+
+// ==========================================
+// Status indicator
+// ==========================================
+
+interface StatusIndicatorProps {
+  status: AgentStatus;
+}
+
+function StatusIndicator({ status }: StatusIndicatorProps): ReactElement {
+  const baseStyle: CSSProperties = {
+    display: "inline-block",
+    width: 8,
+    height: 8,
+    borderRadius: "50%",
+    flexShrink: 0,
+  };
+
+  if (status === "running" || status === "spawning") {
+    return (
+      <span
+        data-testid="status-indicator"
+        data-status={status}
+        style={{
+          ...baseStyle,
+          background: "var(--success)",
+          animation: "agentPulse 1.5s ease-in-out infinite",
+        }}
+        aria-label="Running"
+      />
+    );
+  }
+
+  if (status === "completed") {
+    return (
+      <span
+        data-testid="status-indicator"
+        data-status={status}
+        style={{
+          ...baseStyle,
+          background: "var(--muted)",
+        }}
+        aria-label="Completed"
+      />
+    );
+  }
+
+  // error
+  return (
+    <span
+      data-testid="status-indicator"
+      data-status={status}
+      style={{
+        ...baseStyle,
+        background: "var(--danger)",
+      }}
+      aria-label="Error"
+    />
+  );
+}
+
+// ==========================================
+// Status badge
+// ==========================================
+
+interface StatusBadgeProps {
+  status: AgentStatus;
+}
+
+function StatusBadge({ status }: StatusBadgeProps): ReactElement {
+  const colorMap: Record<AgentStatus, string> = {
+    spawning: "var(--warn)",
+    running: "var(--success)",
+    completed: "var(--muted)",
+    error: "var(--danger)",
+  };
+
+  const labelMap: Record<AgentStatus, string> = {
+    spawning: "spawning",
+    running: "running",
+    completed: "completed",
+    error: "error",
+  };
+
+  return (
+    <span
+      data-testid="status-badge"
+      style={{
+        fontSize: "0.65rem",
+        fontFamily: "var(--mono)",
+        color: colorMap[status],
+        border: `1px solid ${colorMap[status]}`,
+        borderRadius: 3,
+        padding: "1px 5px",
+        lineHeight: 1.6,
+        letterSpacing: "0.03em",
+        flexShrink: 0,
+      }}
+    >
+      {labelMap[status]}
+    </span>
+  );
+}
+
+// ==========================================
+// Component
+// ==========================================
+
+/**
+ * AgentTerminal renders accumulated agent output in a scrollable pre block.
+ * It is intentionally read-only — no keyboard input is accepted.
+ */
+export function AgentTerminal({ agent, className = "", style }: AgentTerminalProps): ReactElement {
+  const outputRef = useRef<HTMLPreElement>(null);
+  const [copied, setCopied] = useState(false);
+  const [tick, setTick] = useState(0);
+
+  // ==========================================
+  // Duration ticker — only runs while active
+  // ==========================================
+
+  useEffect(() => {
+    if (agent.status === "running" || agent.status === "spawning") {
+      const id = setInterval(() => {
+        setTick((t) => t + 1);
+      }, 1000);
+      return (): void => {
+        clearInterval(id);
+      };
+    }
+    return undefined;
+  }, [agent.status]);
+
+  // Consume tick to avoid unused-var lint
+  void tick;
+
+  // ==========================================
+  // Auto-scroll to bottom on new output
+  // ==========================================
+
+  useEffect(() => {
+    const el = outputRef.current;
+    if (el) {
+      el.scrollTop = el.scrollHeight;
+    }
+  }, [agent.outputLines]);
+
+  // ==========================================
+  // Copy to clipboard
+  // ==========================================
+
+  const handleCopy = useCallback((): void => {
+    const text = agent.outputLines.map(stripAnsi).join("");
+    void navigator.clipboard.writeText(text).then(() => {
+      setCopied(true);
+      setTimeout(() => {
+        setCopied(false);
+      }, 2000);
+    });
+  }, [agent.outputLines]);
+
+  // ==========================================
+  // Styles
+  // ==========================================
+
+  const containerStyle: CSSProperties = {
+    display: "flex",
+    flexDirection: "column",
+    height: "100%",
+    background: "var(--bg-deep)",
+    overflow: "hidden",
+    ...style,
+  };
+
+  const headerStyle: CSSProperties = {
+    display: "flex",
+    alignItems: "center",
+    gap: 8,
+    padding: "6px 12px",
+    borderBottom: "1px solid var(--border)",
+    flexShrink: 0,
+    background: "var(--bg-deep)",
+  };
+
+  const titleStyle: CSSProperties = {
+    fontSize: "0.75rem",
+    fontFamily: "var(--mono)",
+    color: "var(--text)",
+    flex: 1,
+    overflow: "hidden",
+    textOverflow: "ellipsis",
+    whiteSpace: "nowrap",
+  };
+
+  const durationStyle: CSSProperties = {
+    fontSize: "0.65rem",
+    fontFamily: "var(--mono)",
+    color: "var(--muted)",
+    flexShrink: 0,
+  };
+
+  const outputStyle: CSSProperties = {
+    flex: 1,
+    overflow: "auto",
+    margin: 0,
+    padding: "8px 12px",
+    fontFamily: "var(--mono)",
+    fontSize: "0.75rem",
+    lineHeight: 1.5,
+    color: "var(--text)",
+    background: "var(--bg-deep)",
+    whiteSpace: "pre-wrap",
+    wordBreak: "break-all",
+  };
+
+  const copyButtonStyle: CSSProperties = {
+    background: "transparent",
+    border: "1px solid var(--border)",
+    borderRadius: 3,
+    color: copied ? "var(--success)" : "var(--muted)",
+    cursor: "pointer",
+    fontSize: "0.65rem",
+    fontFamily: "var(--mono)",
+    padding: "2px 6px",
+    flexShrink: 0,
+  };
+
+  const duration = formatDuration(agent.startedAt, agent.endedAt);
+
+  return (
+    <div
+      className={className}
+      style={containerStyle}
+      role="region"
+      aria-label={`Agent output: ${agent.agentType}`}
+      data-testid="agent-terminal"
+      data-agent-id={agent.agentId}
+    >
+      {/* Header */}
+      <div style={headerStyle} data-testid="agent-terminal-header">
+        <StatusIndicator status={agent.status} />
+
+        <span style={titleStyle} data-testid="agent-type-label">
+          {agent.agentType}
+          {agent.jobId !== undefined ? ` · ${agent.jobId}` : ""}
+        </span>
+
+        <StatusBadge status={agent.status} />
+
+        <span style={durationStyle} data-testid="agent-duration">
+          {duration}
+        </span>
+
+        {/* Copy button */}
+        <button
+          aria-label="Copy agent output"
+          style={copyButtonStyle}
+          onClick={handleCopy}
+          data-testid="copy-button"
+          onMouseEnter={(e): void => {
+            if (!copied) {
+              (e.currentTarget as HTMLButtonElement).style.color = "var(--text)";
+              (e.currentTarget as HTMLButtonElement).style.borderColor = "var(--text-2)";
+            }
+          }}
+          onMouseLeave={(e): void => {
+            if (!copied) {
+              (e.currentTarget as HTMLButtonElement).style.color = "var(--muted)";
+              (e.currentTarget as HTMLButtonElement).style.borderColor = "var(--border)";
+            }
+          }}
+        >
+          {copied ? "copied" : "copy"}
+        </button>
+      </div>
+
+      {/* Output area */}
+      <pre
+        ref={outputRef}
+        style={outputStyle}
+        data-testid="agent-output"
+        aria-label="Agent output log"
+        aria-live="polite"
+        aria-atomic="false"
+      >
+        {agent.outputLines.length === 0 ? (
+          <span style={{ color: "var(--muted)" }}>
+            {agent.status === "spawning" ? "Spawning agent..." : "Waiting for output..."}
+          </span>
+        ) : (
+          agent.outputLines.map(stripAnsi).join("")
+        )}
+      </pre>
+
+      {/* Error message overlay */}
+      {agent.status === "error" && agent.errorMessage !== undefined && (
+        <div
+          style={{
+            padding: "4px 12px",
+            fontSize: "0.7rem",
+            fontFamily: "var(--mono)",
+            color: "var(--danger)",
+            background: "var(--bg-deep)",
+            borderTop: "1px solid var(--border)",
+            flexShrink: 0,
+          }}
+          data-testid="agent-error-message"
+          role="alert"
+        >
+          Error: {agent.errorMessage}
+        </div>
+      )}
+
+      {/* Pulse animation keyframes — injected inline via style tag for zero deps */}
+      <style>{`
+        @keyframes agentPulse {
+          0%, 100% { opacity: 1; }
+          50% { opacity: 0.4; }
+        }
+      `}</style>
+    </div>
+  );
+}
diff --git a/apps/web/src/components/terminal/TerminalPanel.test.tsx b/apps/web/src/components/terminal/TerminalPanel.test.tsx
index 7fc5902..88d611c 100644
--- a/apps/web/src/components/terminal/TerminalPanel.test.tsx
+++ b/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();
+    });
+  });
 });
diff --git a/apps/web/src/components/terminal/TerminalPanel.tsx b/apps/web/src/components/terminal/TerminalPanel.tsx
index 1309db7..6ba4e3a 100644
--- a/apps/web/src/components/terminal/TerminalPanel.tsx
+++ b/apps/web/src/components/terminal/TerminalPanel.tsx
@@ -7,18 +7,25 @@
  * rendering one XTerminal per session and keeping all instances mounted (for
  * scrollback preservation) while switching visibility with display:none.
  *
+ * Also renders read-only agent output tabs from the orchestrator SSE stream
+ * via useAgentStream. Agent tabs are automatically added when agents are active
+ * and can be dismissed when completed or errored.
+ *
  * Features:
- * - "+" button to open a new tab
- * - Per-tab close button
- * - Double-click tab label for inline rename
- * - Auto-creates the first session on connect
+ * - "+" button to open a new terminal tab
+ * - Per-tab close button (terminal) / dismiss button (agent)
+ * - Double-click tab label for inline rename (terminal tabs only)
+ * - Auto-creates the first terminal session on connect
  * - Connection error state
+ * - Agent tabs: read-only, auto-appear, dismissable
  */
 
 import { useState, useEffect, useRef, useCallback } from "react";
 import type { ReactElement, CSSProperties, KeyboardEvent } from "react";
 import { XTerminal } from "./XTerminal";
+import { AgentTerminal } from "./AgentTerminal";
 import { useTerminalSessions } from "@/hooks/useTerminalSessions";
+import { useAgentStream } from "@/hooks/useAgentStream";
 
 // ==========================================
 // Types
@@ -59,6 +66,42 @@ export function TerminalPanel({
     registerOutputCallback,
   } = useTerminalSessions({ token });
 
+  // ==========================================
+  // Agent stream
+  // ==========================================
+
+  const { agents, dismissAgent } = useAgentStream();
+
+  // ==========================================
+  // Active tab state (terminal session OR agent)
+  // "terminal:<sessionId>" or "agent:<agentId>"
+  // ==========================================
+
+  type TabId = string; // prefix-qualified: "terminal:<id>" or "agent:<id>"
+
+  const [activeTabId, setActiveTabId] = useState<TabId | null>(null);
+
+  // Sync activeTabId with the terminal session activeSessionId when no agent tab is selected
+  useEffect(() => {
+    setActiveTabId((prev) => {
+      // If an agent tab is active, don't clobber it
+      if (prev?.startsWith("agent:")) return prev;
+      // Reflect active terminal session
+      if (activeSessionId !== null) return `terminal:${activeSessionId}`;
+      return prev;
+    });
+  }, [activeSessionId]);
+
+  // If the active agent tab is dismissed, fall back to the terminal session
+  useEffect(() => {
+    if (activeTabId?.startsWith("agent:")) {
+      const agentId = activeTabId.slice("agent:".length);
+      if (!agents.has(agentId)) {
+        setActiveTabId(activeSessionId !== null ? `terminal:${activeSessionId}` : null);
+      }
+    }
+  }, [agents, activeTabId, activeSessionId]);
+
   // ==========================================
   // Inline rename state
   // ==========================================
@@ -187,6 +230,16 @@ export function TerminalPanel({
     position: "relative",
   };
 
+  // ==========================================
+  // Agent status dot color
+  // ==========================================
+
+  const agentDotColor = (status: string): string => {
+    if (status === "running" || status === "spawning") return "var(--success)";
+    if (status === "error") return "var(--danger)";
+    return "var(--muted)";
+  };
+
   // ==========================================
   // Render
   // ==========================================
@@ -203,8 +256,10 @@ export function TerminalPanel({
       <div style={headerStyle}>
         {/* Tab bar */}
         <div style={tabBarStyle} role="tablist" aria-label="Terminal tabs">
+          {/* ---- Terminal session tabs ---- */}
           {[...sessions.entries()].map(([sessionId, sessionInfo]) => {
-            const isActive = sessionId === activeSessionId;
+            const tabKey = `terminal:${sessionId}`;
+            const isActive = tabKey === activeTabId;
             const isEditing = sessionId === editingTabId;
 
             const tabStyle: CSSProperties = {
@@ -223,7 +278,7 @@ export function TerminalPanel({
             };
 
             return (
-              <div key={sessionId} style={tabStyle}>
+              <div key={tabKey} style={tabStyle}>
                 {isEditing ? (
                   <input
                     ref={editInputRef}
@@ -262,6 +317,7 @@ export function TerminalPanel({
                       padding: 0,
                     }}
                     onClick={(): void => {
+                      setActiveTabId(tabKey);
                       setActiveSession(sessionId);
                     }}
                     onDoubleClick={(): void => {
@@ -364,6 +420,146 @@ export function TerminalPanel({
               />
             </svg>
           </button>
+
+          {/* ---- Agent section divider (only when agents exist) ---- */}
+          {agents.size > 0 && (
+            <div
+              aria-hidden="true"
+              style={{
+                width: 1,
+                height: 16,
+                background: "var(--border)",
+                marginLeft: 6,
+                marginRight: 4,
+                flexShrink: 0,
+              }}
+            />
+          )}
+
+          {/* ---- Agent tabs ---- */}
+          {[...agents.entries()].map(([agentId, agentSession]) => {
+            const tabKey = `agent:${agentId}`;
+            const isActive = tabKey === activeTabId;
+
+            const canDismiss =
+              agentSession.status === "completed" || agentSession.status === "error";
+
+            const agentTabStyle: CSSProperties = {
+              display: "flex",
+              alignItems: "center",
+              gap: 4,
+              padding: "3px 6px 3px 8px",
+              borderRadius: 4,
+              fontSize: "0.75rem",
+              fontFamily: "var(--mono)",
+              color: isActive ? "var(--text)" : "var(--muted)",
+              background: isActive ? "var(--surface)" : "transparent",
+              border: "none",
+              outline: "none",
+              flexShrink: 0,
+            };
+
+            return (
+              <div
+                key={tabKey}
+                style={agentTabStyle}
+                data-testid="agent-tab"
+                data-agent-id={agentId}
+                data-agent-status={agentSession.status}
+              >
+                {/* Status dot */}
+                <span
+                  aria-hidden="true"
+                  style={{
+                    display: "inline-block",
+                    width: 6,
+                    height: 6,
+                    borderRadius: "50%",
+                    background: agentDotColor(agentSession.status),
+                    flexShrink: 0,
+                  }}
+                />
+
+                {/* Agent tab button — read-only, no rename */}
+                <button
+                  role="tab"
+                  aria-selected={isActive}
+                  style={{
+                    background: "transparent",
+                    border: "none",
+                    outline: "none",
+                    fontFamily: "var(--mono)",
+                    fontSize: "0.75rem",
+                    color: isActive ? "var(--text)" : "var(--muted)",
+                    cursor: "pointer",
+                    padding: 0,
+                    maxWidth: 100,
+                    overflow: "hidden",
+                    textOverflow: "ellipsis",
+                    whiteSpace: "nowrap",
+                  }}
+                  onClick={(): void => {
+                    setActiveTabId(tabKey);
+                  }}
+                  onMouseEnter={(e): void => {
+                    if (!isActive) {
+                      (e.currentTarget as HTMLButtonElement).style.color = "var(--text-2)";
+                    }
+                  }}
+                  onMouseLeave={(e): void => {
+                    if (!isActive) {
+                      (e.currentTarget as HTMLButtonElement).style.color = "var(--muted)";
+                    }
+                  }}
+                  aria-label={`Agent: ${agentSession.agentType}`}
+                >
+                  {agentSession.agentType}
+                </button>
+
+                {/* Dismiss button — only for completed/error agents */}
+                {canDismiss && (
+                  <button
+                    aria-label={`Dismiss ${agentSession.agentType} agent`}
+                    style={{
+                      width: 16,
+                      height: 16,
+                      borderRadius: 3,
+                      display: "flex",
+                      alignItems: "center",
+                      justifyContent: "center",
+                      color: "var(--muted)",
+                      cursor: "pointer",
+                      background: "transparent",
+                      border: "none",
+                      outline: "none",
+                      padding: 0,
+                      flexShrink: 0,
+                    }}
+                    onClick={(): void => {
+                      dismissAgent(agentId);
+                    }}
+                    onMouseEnter={(e): void => {
+                      (e.currentTarget as HTMLButtonElement).style.background = "var(--surface)";
+                      (e.currentTarget as HTMLButtonElement).style.color = "var(--text)";
+                    }}
+                    onMouseLeave={(e): void => {
+                      (e.currentTarget as HTMLButtonElement).style.background = "transparent";
+                      (e.currentTarget as HTMLButtonElement).style.color = "var(--muted)";
+                    }}
+                  >
+                    <svg width="8" height="8" viewBox="0 0 8 8" fill="none" aria-hidden="true">
+                      <path
+                        d="M1 1L7 7M7 1L1 7"
+                        stroke="currentColor"
+                        strokeWidth="1.5"
+                        strokeLinecap="round"
+                      />
+                    </svg>
+                  </button>
+                )}
+              </div>
+            );
+          })}
         </div>
 
         {/* Action buttons */}
@@ -428,8 +624,10 @@ export function TerminalPanel({
 
       {/* Terminal body — keep all XTerminal instances mounted for scrollback */}
       <div style={bodyStyle}>
+        {/* ---- Terminal session panels ---- */}
         {[...sessions.entries()].map(([sessionId, sessionInfo]) => {
-          const isActive = sessionId === activeSessionId;
+          const tabKey = `terminal:${sessionId}`;
+          const isActive = tabKey === activeTabId;
           const termStyle: CSSProperties = {
             display: isActive ? "flex" : "none",
             flex: 1,
@@ -438,7 +636,7 @@ export function TerminalPanel({
           };
 
           return (
-            <div key={sessionId} style={termStyle}>
+            <div key={tabKey} style={termStyle}>
               <XTerminal
                 sessionId={sessionId}
                 sendInput={sendInput}
@@ -458,8 +656,26 @@ export function TerminalPanel({
           );
         })}
 
-        {/* Empty state */}
-        {sessions.size === 0 && (
+        {/* ---- Agent session panels ---- */}
+        {[...agents.entries()].map(([agentId, agentSession]) => {
+          const tabKey = `agent:${agentId}`;
+          const isActive = tabKey === activeTabId;
+          const agentPanelStyle: CSSProperties = {
+            display: isActive ? "flex" : "none",
+            flex: 1,
+            flexDirection: "column",
+            minHeight: 0,
+          };
+
+          return (
+            <div key={tabKey} style={agentPanelStyle}>
+              <AgentTerminal agent={agentSession} style={{ flex: 1, minHeight: 0 }} />
+            </div>
+          );
+        })}
+
+        {/* Empty state — show only when no terminal sessions AND no agent sessions */}
+        {sessions.size === 0 && agents.size === 0 && (
           <div
             style={{
               flex: 1,
diff --git a/apps/web/src/components/terminal/index.ts b/apps/web/src/components/terminal/index.ts
index 9c0adeb..8513d3d 100644
--- a/apps/web/src/components/terminal/index.ts
+++ b/apps/web/src/components/terminal/index.ts
@@ -2,3 +2,5 @@ export type { TerminalPanelProps } from "./TerminalPanel";
 export { TerminalPanel } from "./TerminalPanel";
 export type { XTerminalProps } from "./XTerminal";
 export { XTerminal } from "./XTerminal";
+export type { AgentTerminalProps } from "./AgentTerminal";
+export { AgentTerminal } from "./AgentTerminal";
diff --git a/apps/web/src/hooks/__tests__/useAgentStream.test.ts b/apps/web/src/hooks/__tests__/useAgentStream.test.ts
new file mode 100644
index 0000000..000f22e
--- /dev/null
+++ b/apps/web/src/hooks/__tests__/useAgentStream.test.ts
@@ -0,0 +1,542 @@
+/**
+ * @file useAgentStream.test.ts
+ * @description Unit tests for the useAgentStream hook
+ *
+ * Tests cover:
+ * - SSE event parsing (agent:spawned, agent:output, agent:completed, agent:error)
+ * - Agent lifecycle state transitions
+ * - Auto-reconnect behavior on connection loss
+ * - Cleanup on unmount
+ * - Dismiss agent
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { renderHook, act } from "@testing-library/react";
+import { useAgentStream } from "../useAgentStream";
+
+// ==========================================
+// Mock EventSource
+// ==========================================
+
+interface MockEventSourceInstance {
+  url: string;
+  onopen: (() => void) | null;
+  onerror: ((event: Event) => void) | null;
+  onmessage: ((event: MessageEvent) => void) | null;
+  close: ReturnType<typeof vi.fn>;
+  addEventListener: ReturnType<typeof vi.fn>;
+  dispatchEvent: (type: string, data: string) => void;
+  _listeners: Map<string, ((event: MessageEvent<string>) => void)[]>;
+  readyState: number;
+}
+
+let mockEventSourceInstances: MockEventSourceInstance[] = [];
+
+const MockEventSource = vi.fn(function (this: MockEventSourceInstance, url: string): void {
+  this.url = url;
+  this.onopen = null;
+  this.onerror = null;
+  this.onmessage = null;
+  this.close = vi.fn();
+  this.readyState = 0;
+  this._listeners = new Map();
+
+  this.addEventListener = vi.fn(
+    (type: string, handler: (event: MessageEvent<string>) => void): void => {
+      if (!this._listeners.has(type)) {
+        this._listeners.set(type, []);
+      }
+      const list = this._listeners.get(type);
+      if (list) list.push(handler);
+    }
+  );
+
+  this.dispatchEvent = (type: string, data: string): void => {
+    const handlers = this._listeners.get(type) ?? [];
+    const event = new MessageEvent(type, { data });
+    for (const handler of handlers) {
+      handler(event);
+    }
+  };
+
+  mockEventSourceInstances.push(this);
+});
+
+// Add static constants
+Object.assign(MockEventSource, {
+  CONNECTING: 0,
+  OPEN: 1,
+  CLOSED: 2,
+});
+
+vi.stubGlobal("EventSource", MockEventSource);
+
+// ==========================================
+// Helpers
+// ==========================================
+
+function getLatestES(): MockEventSourceInstance {
+  const es = mockEventSourceInstances[mockEventSourceInstances.length - 1];
+  if (!es) throw new Error("No EventSource instance created");
+  return es;
+}
+
+function triggerOpen(): void {
+  const es = getLatestES();
+  if (es.onopen) es.onopen();
+}
+
+function triggerError(): void {
+  const es = getLatestES();
+  if (es.onerror) es.onerror(new Event("error"));
+}
+
+function emitEvent(type: string, data: unknown): void {
+  const es = getLatestES();
+  es.dispatchEvent(type, JSON.stringify(data));
+}
+
+// ==========================================
+// Tests
+// ==========================================
+
+describe("useAgentStream", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.useFakeTimers();
+    mockEventSourceInstances = [];
+  });
+
+  afterEach(() => {
+    vi.runAllTimers();
+    vi.useRealTimers();
+  });
+
+  // ==========================================
+  // Initialization
+  // ==========================================
+
+  describe("initialization", () => {
+    it("creates an EventSource connecting to /api/orchestrator/events", () => {
+      renderHook(() => useAgentStream());
+      expect(MockEventSource).toHaveBeenCalledWith("/api/orchestrator/events");
+    });
+
+    it("starts with isConnected=false before onopen fires", () => {
+      const { result } = renderHook(() => useAgentStream());
+      expect(result.current.isConnected).toBe(false);
+    });
+
+    it("starts with an empty agents map", () => {
+      const { result } = renderHook(() => useAgentStream());
+      expect(result.current.agents.size).toBe(0);
+    });
+
+    it("sets isConnected=true when EventSource opens", () => {
+      const { result } = renderHook(() => useAgentStream());
+      act(() => {
+        triggerOpen();
+      });
+      expect(result.current.isConnected).toBe(true);
+    });
+
+    it("clears connectionError when EventSource opens", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      // Trigger an error first to set connectionError
+      act(() => {
+        triggerError();
+      });
+
+      // Start a fresh reconnect and open it
+      act(() => {
+        vi.advanceTimersByTime(2000);
+      });
+
+      act(() => {
+        triggerOpen();
+      });
+
+      expect(result.current.connectionError).toBeNull();
+    });
+  });
+
+  // ==========================================
+  // SSE event: agent:spawned
+  // ==========================================
+
+  describe("agent:spawned event", () => {
+    it("adds an agent with status=spawning", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker", jobId: "job-abc" });
+      });
+
+      expect(result.current.agents.has("agent-1")).toBe(true);
+      expect(result.current.agents.get("agent-1")?.status).toBe("spawning");
+    });
+
+    it("sets agentType from the type field", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "planner" });
+      });
+
+      expect(result.current.agents.get("agent-1")?.agentType).toBe("planner");
+    });
+
+    it("defaults agentType to 'agent' when type is missing", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-2" });
+      });
+
+      expect(result.current.agents.get("agent-2")?.agentType).toBe("agent");
+    });
+
+    it("stores jobId when present", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-3", type: "worker", jobId: "job-xyz" });
+      });
+
+      expect(result.current.agents.get("agent-3")?.jobId).toBe("job-xyz");
+    });
+
+    it("starts with empty outputLines", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+      });
+
+      expect(result.current.agents.get("agent-1")?.outputLines).toEqual([]);
+    });
+  });
+
+  // ==========================================
+  // SSE event: agent:output
+  // ==========================================
+
+  describe("agent:output event", () => {
+    it("appends output to the agent's outputLines", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:output", { agentId: "agent-1", data: "Hello world\n" });
+      });
+
+      expect(result.current.agents.get("agent-1")?.outputLines).toContain("Hello world\n");
+    });
+
+    it("transitions status from spawning to running on first output", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:output", { agentId: "agent-1", data: "Starting...\n" });
+      });
+
+      expect(result.current.agents.get("agent-1")?.status).toBe("running");
+    });
+
+    it("accumulates multiple output lines", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:output", { agentId: "agent-1", data: "Line 1\n" });
+        emitEvent("agent:output", { agentId: "agent-1", data: "Line 2\n" });
+        emitEvent("agent:output", { agentId: "agent-1", data: "Line 3\n" });
+      });
+
+      const lines = result.current.agents.get("agent-1")?.outputLines ?? [];
+      expect(lines).toHaveLength(3);
+      expect(lines[0]).toBe("Line 1\n");
+      expect(lines[1]).toBe("Line 2\n");
+      expect(lines[2]).toBe("Line 3\n");
+    });
+
+    it("creates a new agent entry if output arrives before spawned event", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:output", { agentId: "unknown-agent", data: "Surprise output\n" });
+      });
+
+      expect(result.current.agents.has("unknown-agent")).toBe(true);
+      expect(result.current.agents.get("unknown-agent")?.status).toBe("running");
+    });
+  });
+
+  // ==========================================
+  // SSE event: agent:completed
+  // ==========================================
+
+  describe("agent:completed event", () => {
+    it("sets status to completed", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:output", { agentId: "agent-1", data: "Working...\n" });
+        emitEvent("agent:completed", { agentId: "agent-1", exitCode: 0 });
+      });
+
+      expect(result.current.agents.get("agent-1")?.status).toBe("completed");
+    });
+
+    it("stores the exitCode", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:completed", { agentId: "agent-1", exitCode: 42 });
+      });
+
+      expect(result.current.agents.get("agent-1")?.exitCode).toBe(42);
+    });
+
+    it("sets endedAt timestamp", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:completed", { agentId: "agent-1", exitCode: 0 });
+      });
+
+      expect(result.current.agents.get("agent-1")?.endedAt).toBeDefined();
+    });
+
+    it("ignores completed event for unknown agent", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:completed", { agentId: "ghost-agent", exitCode: 0 });
+      });
+
+      expect(result.current.agents.has("ghost-agent")).toBe(false);
+    });
+  });
+
+  // ==========================================
+  // SSE event: agent:error
+  // ==========================================
+
+  describe("agent:error event", () => {
+    it("sets status to error", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:error", { agentId: "agent-1", error: "Out of memory" });
+      });
+
+      expect(result.current.agents.get("agent-1")?.status).toBe("error");
+    });
+
+    it("stores the error message", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:error", { agentId: "agent-1", error: "Segfault" });
+      });
+
+      expect(result.current.agents.get("agent-1")?.errorMessage).toBe("Segfault");
+    });
+
+    it("sets endedAt on error", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:error", { agentId: "agent-1", error: "Crash" });
+      });
+
+      expect(result.current.agents.get("agent-1")?.endedAt).toBeDefined();
+    });
+
+    it("ignores error event for unknown agent", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:error", { agentId: "ghost-agent", error: "Crash" });
+      });
+
+      expect(result.current.agents.has("ghost-agent")).toBe(false);
+    });
+  });
+
+  // ==========================================
+  // Reconnect behavior
+  // ==========================================
+
+  describe("auto-reconnect", () => {
+    it("sets isConnected=false on error", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+      });
+      act(() => {
+        triggerError();
+      });
+
+      expect(result.current.isConnected).toBe(false);
+    });
+
+    it("sets connectionError on error", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        triggerError();
+      });
+
+      expect(result.current.connectionError).not.toBeNull();
+    });
+
+    it("creates a new EventSource after reconnect delay", () => {
+      renderHook(() => useAgentStream());
+      const initialCount = mockEventSourceInstances.length;
+
+      act(() => {
+        triggerOpen();
+        triggerError();
+      });
+
+      act(() => {
+        vi.advanceTimersByTime(1500); // initial backoff = 1000ms
+      });
+
+      expect(mockEventSourceInstances.length).toBeGreaterThan(initialCount);
+    });
+
+    it("closes the old EventSource before reconnecting", () => {
+      renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        triggerError();
+      });
+
+      const closedInstance = mockEventSourceInstances[0];
+      expect(closedInstance?.close).toHaveBeenCalled();
+    });
+  });
+
+  // ==========================================
+  // Cleanup on unmount
+  // ==========================================
+
+  describe("cleanup on unmount", () => {
+    it("closes EventSource when the hook is unmounted", () => {
+      const { unmount } = renderHook(() => useAgentStream());
+
+      const es = getLatestES();
+      unmount();
+
+      expect(es.close).toHaveBeenCalled();
+    });
+
+    it("does not attempt to reconnect after unmount", () => {
+      const { unmount } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        triggerError();
+      });
+
+      const countBeforeUnmount = mockEventSourceInstances.length;
+
+      unmount();
+
+      act(() => {
+        vi.advanceTimersByTime(5000);
+      });
+
+      // No new instances created after unmount
+      expect(mockEventSourceInstances.length).toBe(countBeforeUnmount);
+    });
+  });
+
+  // ==========================================
+  // Dismiss agent
+  // ==========================================
+
+  describe("dismissAgent", () => {
+    it("removes the agent from the map", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+        emitEvent("agent:completed", { agentId: "agent-1", exitCode: 0 });
+      });
+
+      act(() => {
+        result.current.dismissAgent("agent-1");
+      });
+
+      expect(result.current.agents.has("agent-1")).toBe(false);
+    });
+
+    it("is a no-op for unknown agentId", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        emitEvent("agent:spawned", { agentId: "agent-1", type: "worker" });
+      });
+
+      act(() => {
+        result.current.dismissAgent("nonexistent-agent");
+      });
+
+      expect(result.current.agents.has("agent-1")).toBe(true);
+    });
+  });
+
+  // ==========================================
+  // Malformed event handling
+  // ==========================================
+
+  describe("malformed events", () => {
+    it("ignores malformed JSON without throwing", () => {
+      const { result } = renderHook(() => useAgentStream());
+
+      act(() => {
+        triggerOpen();
+        // Dispatch raw bad JSON
+        const es = getLatestES();
+        es.dispatchEvent("agent:spawned", "NOT JSON {{{");
+      });
+
+      // Should not crash, agents map stays empty
+      expect(result.current.agents.size).toBe(0);
+    });
+  });
+});
diff --git a/apps/web/src/hooks/useAgentStream.ts b/apps/web/src/hooks/useAgentStream.ts
new file mode 100644
index 0000000..45840db
--- /dev/null
+++ b/apps/web/src/hooks/useAgentStream.ts
@@ -0,0 +1,319 @@
+"use client";
+
+/**
+ * useAgentStream hook
+ *
+ * Connects to the orchestrator SSE event stream at /api/orchestrator/events
+ * and maintains a Map of agentId → AgentSession with accumulated output,
+ * status, and lifecycle metadata.
+ *
+ * SSE event types consumed:
+ * - agent:spawned  — { agentId, type, jobId }
+ * - agent:output   — { agentId, data } (stdout/stderr lines)
+ * - agent:completed — { agentId, exitCode, result }
+ * - agent:error    — { agentId, error }
+ *
+ * Features:
+ * - Auto-reconnect with exponential backoff on connection loss
+ * - Cleans up EventSource on unmount
+ * - Accumulates output lines per agent
+ */
+
+import { useEffect, useRef, useState, useCallback } from "react";
+
+// ==========================================
+// Types
+// ==========================================
+
+export type AgentStatus = "spawning" | "running" | "completed" | "error";
+
+export interface AgentSession {
+  /** Agent identifier from the orchestrator */
+  agentId: string;
+  /** Agent type or name (e.g., "worker", "planner") */
+  agentType: string;
+  /** Optional job ID this agent is associated with */
+  jobId?: string;
+  /** Current lifecycle status */
+  status: AgentStatus;
+  /** Accumulated output lines (stdout/stderr) */
+  outputLines: string[];
+  /** Timestamp when the agent was spawned */
+  startedAt: number;
+  /** Timestamp when the agent completed or errored */
+  endedAt?: number;
+  /** Exit code from agent:completed event */
+  exitCode?: number;
+  /** Error message from agent:error event */
+  errorMessage?: string;
+}
+
+export interface UseAgentStreamReturn {
+  /** Map of agentId → AgentSession */
+  agents: Map<string, AgentSession>;
+  /** Whether the SSE stream is currently connected */
+  isConnected: boolean;
+  /** Connection error message, if any */
+  connectionError: string | null;
+  /** Dismiss (remove) an agent tab by agentId */
+  dismissAgent: (agentId: string) => void;
+}
+
+// ==========================================
+// SSE payload shapes
+// ==========================================
+
+interface SpawnedPayload {
+  agentId: string;
+  type?: string;
+  jobId?: string;
+}
+
+interface OutputPayload {
+  agentId: string;
+  data: string;
+}
+
+interface CompletedPayload {
+  agentId: string;
+  exitCode?: number;
+  result?: unknown;
+}
+
+interface ErrorPayload {
+  agentId: string;
+  error?: string;
+}
+
+// ==========================================
+// Backoff config
+// ==========================================
+
+const RECONNECT_BASE_MS = 1_000;
+const RECONNECT_MAX_MS = 30_000;
+const RECONNECT_MULTIPLIER = 2;
+
+// ==========================================
+// Hook
+// ==========================================
+
+/**
+ * Connects to the orchestrator SSE stream and tracks all agent sessions.
+ *
+ * @returns Agent sessions map, connection status, and dismiss callback
+ */
+export function useAgentStream(): UseAgentStreamReturn {
+  const [agents, setAgents] = useState<Map<string, AgentSession>>(new Map());
+  const [isConnected, setIsConnected] = useState(false);
+  const [connectionError, setConnectionError] = useState<string | null>(null);
+
+  const eventSourceRef = useRef<EventSource | null>(null);
+  const reconnectTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+  const reconnectDelayRef = useRef<number>(RECONNECT_BASE_MS);
+  const isMountedRef = useRef(true);
+
+  // ==========================================
+  // Agent state update helpers
+  // ==========================================
+
+  const handleAgentSpawned = useCallback((payload: SpawnedPayload): void => {
+    setAgents((prev) => {
+      const next = new Map(prev);
+      next.set(payload.agentId, {
+        agentId: payload.agentId,
+        agentType: payload.type ?? "agent",
+        ...(payload.jobId !== undefined ? { jobId: payload.jobId } : {}),
+        status: "spawning",
+        outputLines: [],
+        startedAt: Date.now(),
+      });
+      return next;
+    });
+  }, []);
+
+  const handleAgentOutput = useCallback((payload: OutputPayload): void => {
+    setAgents((prev) => {
+      const existing = prev.get(payload.agentId);
+      if (!existing) {
+        // First output for an agent we haven't seen spawned — create it
+        const next = new Map(prev);
+        next.set(payload.agentId, {
+          agentId: payload.agentId,
+          agentType: "agent",
+          status: "running",
+          outputLines: [payload.data],
+          startedAt: Date.now(),
+        });
+        return next;
+      }
+
+      const next = new Map(prev);
+      next.set(payload.agentId, {
+        ...existing,
+        status: existing.status === "spawning" ? "running" : existing.status,
+        outputLines: [...existing.outputLines, payload.data],
+      });
+      return next;
+    });
+  }, []);
+
+  const handleAgentCompleted = useCallback((payload: CompletedPayload): void => {
+    setAgents((prev) => {
+      const existing = prev.get(payload.agentId);
+      if (!existing) return prev;
+
+      const next = new Map(prev);
+      next.set(payload.agentId, {
+        ...existing,
+        status: "completed",
+        endedAt: Date.now(),
+        ...(payload.exitCode !== undefined ? { exitCode: payload.exitCode } : {}),
+      });
+      return next;
+    });
+  }, []);
+
+  const handleAgentError = useCallback((payload: ErrorPayload): void => {
+    setAgents((prev) => {
+      const existing = prev.get(payload.agentId);
+      if (!existing) return prev;
+
+      const next = new Map(prev);
+      next.set(payload.agentId, {
+        ...existing,
+        status: "error",
+        endedAt: Date.now(),
+        ...(payload.error !== undefined ? { errorMessage: payload.error } : {}),
+      });
+      return next;
+    });
+  }, []);
+
+  // ==========================================
+  // SSE connection
+  // ==========================================
+
+  const connect = useCallback((): void => {
+    if (!isMountedRef.current) return;
+    if (typeof EventSource === "undefined") return;
+
+    // Clean up any existing connection
+    if (eventSourceRef.current) {
+      eventSourceRef.current.close();
+      eventSourceRef.current = null;
+    }
+
+    const es = new EventSource("/api/orchestrator/events");
+    eventSourceRef.current = es;
+
+    es.onopen = (): void => {
+      if (!isMountedRef.current) return;
+      setIsConnected(true);
+      setConnectionError(null);
+      reconnectDelayRef.current = RECONNECT_BASE_MS;
+    };
+
+    es.onerror = (): void => {
+      if (!isMountedRef.current) return;
+      setIsConnected(false);
+
+      es.close();
+      eventSourceRef.current = null;
+
+      // Schedule reconnect with backoff
+      const delay = reconnectDelayRef.current;
+      reconnectDelayRef.current = Math.min(delay * RECONNECT_MULTIPLIER, RECONNECT_MAX_MS);
+
+      const delaySecs = Math.round(delay / 1000).toString();
+      setConnectionError(`SSE connection lost. Reconnecting in ${delaySecs}s...`);
+
+      reconnectTimerRef.current = setTimeout(() => {
+        if (isMountedRef.current) {
+          connect();
+        }
+      }, delay);
+    };
+
+    es.addEventListener("agent:spawned", (event: MessageEvent<string>) => {
+      if (!isMountedRef.current) return;
+      try {
+        const payload = JSON.parse(event.data) as SpawnedPayload;
+        handleAgentSpawned(payload);
+      } catch {
+        // Ignore malformed events
+      }
+    });
+
+    es.addEventListener("agent:output", (event: MessageEvent<string>) => {
+      if (!isMountedRef.current) return;
+      try {
+        const payload = JSON.parse(event.data) as OutputPayload;
+        handleAgentOutput(payload);
+      } catch {
+        // Ignore malformed events
+      }
+    });
+
+    es.addEventListener("agent:completed", (event: MessageEvent<string>) => {
+      if (!isMountedRef.current) return;
+      try {
+        const payload = JSON.parse(event.data) as CompletedPayload;
+        handleAgentCompleted(payload);
+      } catch {
+        // Ignore malformed events
+      }
+    });
+
+    es.addEventListener("agent:error", (event: MessageEvent<string>) => {
+      if (!isMountedRef.current) return;
+      try {
+        const payload = JSON.parse(event.data) as ErrorPayload;
+        handleAgentError(payload);
+      } catch {
+        // Ignore malformed events
+      }
+    });
+  }, [handleAgentSpawned, handleAgentOutput, handleAgentCompleted, handleAgentError]);
+
+  // ==========================================
+  // Mount / unmount
+  // ==========================================
+
+  useEffect(() => {
+    isMountedRef.current = true;
+    connect();
+
+    return (): void => {
+      isMountedRef.current = false;
+
+      if (reconnectTimerRef.current !== null) {
+        clearTimeout(reconnectTimerRef.current);
+        reconnectTimerRef.current = null;
+      }
+
+      if (eventSourceRef.current) {
+        eventSourceRef.current.close();
+        eventSourceRef.current = null;
+      }
+    };
+  }, [connect]);
+
+  // ==========================================
+  // Dismiss agent
+  // ==========================================
+
+  const dismissAgent = useCallback((agentId: string): void => {
+    setAgents((prev) => {
+      const next = new Map(prev);
+      next.delete(agentId);
+      return next;
+    });
+  }, []);
+
+  return {
+    agents,
+    isConnected,
+    connectionError,
+    dismissAgent,
+  };
+}
-- 
2.49.1