diff --git a/backend/agenteval/intelligent_eval/fault_tolerance.py b/backend/agenteval/intelligent_eval/fault_tolerance.py
new file mode 100644
index 0000000..15db450
--- /dev/null
+++ b/backend/agenteval/intelligent_eval/fault_tolerance.py
@@ -0,0 +1,204 @@
+"""Fault tolerance and recovery for cron pool (故障恢复).
+
+Handles:
+- Stuck cron detection and cleanup
+- State reconciliation (platform DB vs OpenClaw state)
+- Platform restart recovery
+- OpenClaw restart recovery
+"""
+
+import logging
+from datetime import timedelta
+
+from sqlmodel import Session, select
+
+from agenteval.intelligent_eval import cron_pool
+from agenteval.intelligent_eval.openclaw_client import OpenClawClient
+from agenteval.storage.db import (
+    IntelligentEvalTaskQueueDB,
+    OpenClawCronPoolDB,
+    utc_now,
+)
+
+_logger = logging.getLogger("agenteval")
+
+
+async def detect_and_handle_stuck_crons(session: Session, client: OpenClawClient) -> int:
+    """Detect and handle stuck crons.
+
+    Returns:
+        Number of stuck crons handled
+    """
+    stuck_crons = cron_pool.detect_stuck_crons(session)
+
+    for cron in stuck_crons:
+        await cron_pool.handle_stuck_cron(cron, session, client)
+
+    if stuck_crons:
+        _logger.info(f"Handled {len(stuck_crons)} stuck crons")
+
+    return len(stuck_crons)
+
+
+async def reconcile_state(session: Session, client: OpenClawClient) -> dict:
+    """Reconcile platform DB state with OpenClaw state.
+
+    Checks:
+    1. Platform DB has crons that OpenClaw doesn't → mark as stuck
+    2. OpenClaw has crons that platform DB doesn't → sync to DB
+    3. Assigned tasks have inactive crons → requeue tasks
+
+    Returns:
+        Dict with reconciliation stats
+    """
+    stats = {
+        "orphaned_crons": 0,
+        "missing_crons": 0,
+        "requeued_tasks": 0,
+    }
+
+    # Get all crons from both sides
+    db_crons = session.exec(select(OpenClawCronPoolDB)).all()
+    openclaw_crons = await client.list_crons()
+    openclaw_cron_ids = {c.id for c in openclaw_crons}
+
+    # Check 1: Platform DB has crons that OpenClaw doesn't
+    for db_cron in db_crons:
+        if db_cron.openclaw_cron_id not in openclaw_cron_ids:
+            _logger.warning(f"Cron {db_cron.openclaw_cron_id} exists in DB but not in OpenClaw")
+            db_cron.status = "stuck"
+            db_cron.updated_at = utc_now()
+            stats["orphaned_crons"] += 1
+
+    session.commit()
+
+    # Check 2: OpenClaw has crons that platform DB doesn't
+    synced = await cron_pool.sync_cron_states(session, client)
+    stats["missing_crons"] = synced
+
+    # Check 3: Assigned tasks have inactive crons
+    assigned_tasks = session.exec(
+        select(IntelligentEvalTaskQueueDB).where(IntelligentEvalTaskQueueDB.status == "assigned")
+    ).all()
+
+    for task in assigned_tasks:
+        if task.assigned_cron_id is None:
+            continue
+
+        # Check if cron is still active
+        cron = session.exec(
+            select(OpenClawCronPoolDB).where(
+                OpenClawCronPoolDB.openclaw_cron_id == task.assigned_cron_id
+            )
+        ).first()
+
+        if cron is None or cron.status == "stuck":
+            _logger.warning(f"Task {task.id} assigned to inactive cron {task.assigned_cron_id}")
+
+            # Mark task as failed
+            from agenteval.intelligent_eval.task_queue import complete_task
+
+            complete_task(task.id, False, "Cron inactive", session)
+
+            # Requeue task
+            new_task = IntelligentEvalTaskQueueDB(
+                eval_id=task.eval_id,
+                status="pending",
+                priority=1,  # High priority
+                reason="cron_inactive_retry",
+            )
+            session.add(new_task)
+            stats["requeued_tasks"] += 1
+
+    session.commit()
+
+    if stats["orphaned_crons"] or stats["missing_crons"] or stats["requeued_tasks"]:
+        _logger.info(f"State reconciliation: {stats}")
+
+    return stats
+
+
+async def recover_from_platform_restart(session: Session, client: OpenClawClient) -> dict:
+    """Recover from platform restart.
+
+    Scans all assigned tasks and checks if their crons are still active.
+    If not, requeues the tasks.
+
+    Returns:
+        Dict with recovery stats
+    """
+    stats = {
+        "assigned_tasks_checked": 0,
+        "requeued_tasks": 0,
+    }
+
+    # Get all assigned tasks
+    assigned_tasks = session.exec(
+        select(IntelligentEvalTaskQueueDB).where(IntelligentEvalTaskQueueDB.status == "assigned")
+    ).all()
+
+    stats["assigned_tasks_checked"] = len(assigned_tasks)
+
+    for task in assigned_tasks:
+        if task.assigned_cron_id is None:
+            continue
+
+        # Check if cron exists and is active
+        cron = session.exec(
+            select(OpenClawCronPoolDB).where(
+                OpenClawCronPoolDB.openclaw_cron_id == task.assigned_cron_id
+            )
+        ).first()
+
+        # Check if cron is active (heartbeat within last 5 minutes)
+        if cron:
+            threshold = utc_now() - timedelta(minutes=5)
+            if cron.last_active_at < threshold:
+                cron = None  # Treat as inactive
+
+        if cron is None:
+            _logger.info(f"Requeuing task {task.id} (cron inactive after restart)")
+
+            # Mark task as failed
+            from agenteval.intelligent_eval.task_queue import complete_task
+
+            complete_task(task.id, False, "Platform restart", session)
+
+            # Requeue task
+            new_task = IntelligentEvalTaskQueueDB(
+                eval_id=task.eval_id,
+                status="pending",
+                priority=1,
+                reason="platform_restart_retry",
+            )
+            session.add(new_task)
+            stats["requeued_tasks"] += 1
+
+    session.commit()
+
+    if stats["requeued_tasks"]:
+        _logger.info(f"Platform restart recovery: {stats}")
+
+    return stats
+
+
+async def recover_from_openclaw_restart(session: Session, client: OpenClawClient) -> dict:
+    """Recover from OpenClaw restart.
+
+    OpenClaw crons persist their state in SQLite, so they should resume
+    automatically. This function syncs the state to platform DB.
+
+    Returns:
+        Dict with recovery stats
+    """
+    # Sync cron states from OpenClaw to platform DB
+    synced = await cron_pool.sync_cron_states(session, client)
+
+    stats = {
+        "synced_crons": synced,
+    }
+
+    if synced:
+        _logger.info(f"OpenClaw restart recovery: {stats}")
+
+    return stats
diff --git a/tests/integration/test_fault_tolerance_e2e.py b/tests/integration/test_fault_tolerance_e2e.py
new file mode 100644
index 0000000..8fa4c36
--- /dev/null
+++ b/tests/integration/test_fault_tolerance_e2e.py
@@ -0,0 +1,227 @@
+"""Integration tests for fault tolerance and recovery."""
+
+from datetime import timedelta
+
+import pytest
+from fastapi.testclient import TestClient
+from sqlmodel import Session, SQLModel, create_engine, select
+from unittest.mock import AsyncMock
+
+from agenteval.intelligent_eval.openclaw_client import OpenClawClient, OpenClawCron
+from agenteval.storage.db import (
+    IntelligentEvalTaskQueueDB,
+    OpenClawCronPoolDB,
+    utc_now,
+)
+from agenteval.web.app import app
+from agenteval.web.deps import get_db
+
+
+@pytest.fixture()
+def client(tmp_path):
+    """Create a TestClient with a fresh database."""
+    from agenteval.storage.db import (  # noqa: F401
+        IntelligentEvalTaskQueueDB,
+        OpenClawCronPoolDB,
+    )
+
+    engine = create_engine(
+        f"sqlite:///{tmp_path / 'test.db'}",
+        connect_args={"check_same_thread": False},
+    )
+    SQLModel.metadata.create_all(engine)
+    session = Session(engine)
+
+    def override_get_db():
+        try:
+            yield session
+        finally:
+            pass
+
+    app.dependency_overrides[get_db] = override_get_db
+    client = TestClient(app)
+    yield client
+    app.dependency_overrides.clear()
+    session.close()
+    engine.dispose()
+
+
+@pytest.fixture()
+def db_session(client):
+    """Get the database session from the client fixture."""
+    return next(app.dependency_overrides[get_db]())
+
+
+@pytest.fixture()
+def mock_openclaw_client():
+    """Mock OpenClaw client."""
+    client = OpenClawClient()
+    client.list_crons = AsyncMock(return_value=[])
+    client.sync_cron_states = AsyncMock(return_value=0)
+    client.delete_cron = AsyncMock()
+    client.create_cron = AsyncMock(return_value="new-cron")
+    return client
+
+
+def test_stuck_cron_detection_api(client: TestClient, db_session: Session):
+    """Test stuck cron detection via API."""
+    # Create stuck cron
+    cron = OpenClawCronPoolDB(
+        openclaw_cron_id="stuck-cron",
+        status="busy",
+        current_eval_id="eval-1",
+        last_active_at=utc_now() - timedelta(minutes=15),
+    )
+    db_session.add(cron)
+    db_session.commit()
+
+    # Verify cron is stuck
+    from agenteval.intelligent_eval.cron_pool import detect_stuck_crons
+
+    stuck = detect_stuck_crons(db_session)
+    assert len(stuck) == 1
+    assert stuck[0].openclaw_cron_id == "stuck-cron"
+
+
+def test_task_requeue_after_cron_stuck(client: TestClient, db_session: Session):
+    """Test task requeue after cron gets stuck."""
+    # Create stuck cron with assigned task
+    cron = OpenClawCronPoolDB(
+        openclaw_cron_id="stuck-cron",
+        status="busy",
+        current_eval_id="eval-1",
+        last_active_at=utc_now() - timedelta(minutes=15),
+    )
+    db_session.add(cron)
+
+    task = IntelligentEvalTaskQueueDB(
+        eval_id="eval-1",
+        status="assigned",
+        priority=1,
+        reason="slot_due",
+        assigned_cron_id="stuck-cron",
+    )
+    db_session.add(task)
+    db_session.commit()
+
+    # Simulate handling stuck cron
+    from agenteval.intelligent_eval.cron_pool import handle_stuck_cron
+    from unittest.mock import MagicMock
+
+    mock_client = MagicMock(spec=OpenClawClient)
+    mock_client.delete_cron = AsyncMock()
+    mock_client.create_cron = AsyncMock(return_value="new-cron")
+
+    import asyncio
+
+    asyncio.run(handle_stuck_cron(cron, db_session, mock_client))
+
+    # Verify task requeued
+    db_session.refresh(task)
+    assert task.status == "failed"
+
+    new_task = db_session.exec(
+        select(IntelligentEvalTaskQueueDB).where(
+            IntelligentEvalTaskQueueDB.eval_id == "eval-1",
+            IntelligentEvalTaskQueueDB.status == "pending",
+        )
+    ).first()
+    assert new_task is not None
+    assert new_task.reason == "cron_stuck_retry"
+
+
+def test_state_reconciliation_api(client: TestClient, db_session: Session):
+    """Test state reconciliation via API."""
+    # Create orphan cron (exists in DB but not in OpenClaw)
+    cron = OpenClawCronPoolDB(
+        openclaw_cron_id="orphan-cron",
+        status="idle",
+        last_active_at=utc_now(),
+    )
+    db_session.add(cron)
+    db_session.commit()
+
+    # Mock OpenClaw client
+    from agenteval.intelligent_eval import fault_tolerance
+
+    mock_client = OpenClawClient()
+    mock_client.list_crons = AsyncMock(return_value=[])
+    mock_client.sync_cron_states = AsyncMock(return_value=0)
+
+    import asyncio
+
+    stats = asyncio.run(fault_tolerance.reconcile_state(db_session, mock_client))
+
+    assert stats["orphaned_crons"] == 1
+
+    # Verify cron marked as stuck
+    db_session.refresh(cron)
+    assert cron.status == "stuck"
+
+
+def test_platform_restart_recovery(client: TestClient, db_session: Session):
+    """Test platform restart recovery."""
+    # Create task assigned to inactive cron
+    task = IntelligentEvalTaskQueueDB(
+        eval_id="eval-1",
+        status="assigned",
+        priority=1,
+        reason="slot_due",
+        assigned_cron_id="inactive-cron",
+    )
+    db_session.add(task)
+    db_session.commit()
+
+    # Mock OpenClaw client
+    from agenteval.intelligent_eval import fault_tolerance
+
+    mock_client = OpenClawClient()
+    mock_client.list_crons = AsyncMock(return_value=[])
+
+    import asyncio
+
+    stats = asyncio.run(fault_tolerance.recover_from_platform_restart(db_session, mock_client))
+
+    assert stats["assigned_tasks_checked"] == 1
+    assert stats["requeued_tasks"] == 1
+
+    # Verify task requeued
+    new_task = db_session.exec(
+        select(IntelligentEvalTaskQueueDB).where(
+            IntelligentEvalTaskQueueDB.eval_id == "eval-1",
+            IntelligentEvalTaskQueueDB.status == "pending",
+        )
+    ).first()
+    assert new_task is not None
+    assert new_task.reason == "platform_restart_retry"
+
+
+def test_openclaw_restart_recovery(client: TestClient, db_session: Session):
+    """Test OpenClaw restart recovery."""
+    # Mock OpenClaw client returning recovered crons
+    from agenteval.intelligent_eval import fault_tolerance
+
+    mock_client = OpenClawClient()
+    mock_client.list_crons = AsyncMock(
+        return_value=[
+            OpenClawCron(
+                id="recovered-cron",
+                name="worker-1",
+                schedule="* * * * *",
+                enabled=True,
+                state={"status": "idle"},
+            )
+        ]
+    )
+
+    import asyncio
+
+    stats = asyncio.run(fault_tolerance.recover_from_openclaw_restart(db_session, mock_client))
+
+    assert stats["synced_crons"] == 1
+
+    # Verify cron synced to DB
+    cron = db_session.exec(
+        select(OpenClawCronPoolDB).where(OpenClawCronPoolDB.openclaw_cron_id == "recovered-cron")
+    ).first()
+    assert cron is not None
diff --git a/tests/unit/test_fault_tolerance.py b/tests/unit/test_fault_tolerance.py
new file mode 100644
index 0000000..7177511
--- /dev/null
+++ b/tests/unit/test_fault_tolerance.py
@@ -0,0 +1,206 @@
+"""Unit tests for fault tolerance and recovery."""
+
+from datetime import timedelta
+from unittest.mock import AsyncMock, MagicMock
+
+import pytest
+from sqlmodel import Session, select
+
+from agenteval.intelligent_eval import fault_tolerance
+from agenteval.intelligent_eval.openclaw_client import OpenClawClient
+from agenteval.storage.db import (
+    IntelligentEvalTaskQueueDB,
+    OpenClawCronPoolDB,
+    utc_now,
+)
+
+
+@pytest.fixture()
+def mock_openclaw_client():
+    """Mock OpenClaw client."""
+    client = MagicMock(spec=OpenClawClient)
+    client.list_crons = AsyncMock(return_value=[])
+    client.sync_cron_states = AsyncMock(return_value=0)
+    return client
+
+
+async def test_detect_and_handle_stuck_crons(db_session: Session, mock_openclaw_client):
+    """Test detecting and handling stuck crons."""
+    # Create stuck cron
+    cron = OpenClawCronPoolDB(
+        openclaw_cron_id="stuck-cron",
+        status="busy",
+        current_eval_id="eval-1",
+        last_active_at=utc_now() - timedelta(minutes=15),
+    )
+    db_session.add(cron)
+
+    task = IntelligentEvalTaskQueueDB(
+        eval_id="eval-1",
+        status="assigned",
+        priority=1,
+        reason="slot_due",
+        assigned_cron_id="stuck-cron",
+    )
+    db_session.add(task)
+    db_session.commit()
+
+    # Mock OpenClaw client methods
+    mock_openclaw_client.delete_cron = AsyncMock()
+    mock_openclaw_client.create_cron = AsyncMock(return_value="new-cron")
+
+    handled = await fault_tolerance.detect_and_handle_stuck_crons(db_session, mock_openclaw_client)
+    assert handled == 1
+
+    # Verify task requeued
+    db_session.refresh(task)
+    assert task.status == "failed"
+    assert task.error == "Cron stuck"
+
+    # Verify new task created
+    new_task = db_session.exec(
+        select(IntelligentEvalTaskQueueDB).where(
+            IntelligentEvalTaskQueueDB.eval_id == "eval-1",
+            IntelligentEvalTaskQueueDB.status == "pending",
+        )
+    ).first()
+    assert new_task is not None
+    assert new_task.reason == "cron_stuck_retry"
+
+
+async def test_reconcile_state_orphaned_crons(db_session: Session, mock_openclaw_client):
+    """Test reconciliation when platform DB has crons that OpenClaw doesn't."""
+    # Create cron in DB
+    cron = OpenClawCronPoolDB(
+        openclaw_cron_id="orphan-cron",
+        status="idle",
+        last_active_at=utc_now(),
+    )
+    db_session.add(cron)
+    db_session.commit()
+
+    # Mock OpenClaw returning empty list (cron doesn't exist)
+    mock_openclaw_client.list_crons = AsyncMock(return_value=[])
+
+    stats = await fault_tolerance.reconcile_state(db_session, mock_openclaw_client)
+    assert stats["orphaned_crons"] == 1
+
+    # Verify cron marked as stuck
+    db_session.refresh(cron)
+    assert cron.status == "stuck"
+
+
+async def test_reconcile_state_missing_crons(db_session: Session, mock_openclaw_client):
+    """Test reconciliation when OpenClaw has crons that platform DB doesn't."""
+    from agenteval.intelligent_eval.openclaw_client import OpenClawCron
+
+    # Mock OpenClaw returning a cron
+    mock_openclaw_client.list_crons = AsyncMock(
+        return_value=[
+            OpenClawCron(
+                id="missing-cron",
+                name="worker-1",
+                schedule="* * * * *",
+                enabled=True,
+                state={"status": "idle"},
+            )
+        ]
+    )
+
+    stats = await fault_tolerance.reconcile_state(db_session, mock_openclaw_client)
+    assert stats["missing_crons"] == 1
+
+    # Verify cron synced to DB
+    cron = db_session.exec(
+        select(OpenClawCronPoolDB).where(OpenClawCronPoolDB.openclaw_cron_id == "missing-cron")
+    ).first()
+    assert cron is not None
+
+
+async def test_reconcile_state_requeue_inactive_tasks(db_session: Session, mock_openclaw_client):
+    """Test requeuing tasks assigned to inactive crons."""
+    # Create task assigned to non-existent cron
+    task = IntelligentEvalTaskQueueDB(
+        eval_id="eval-1",
+        status="assigned",
+        priority=1,
+        reason="slot_due",
+        assigned_cron_id="nonexistent-cron",
+    )
+    db_session.add(task)
+    db_session.commit()
+
+    mock_openclaw_client.list_crons = AsyncMock(return_value=[])
+
+    stats = await fault_tolerance.reconcile_state(db_session, mock_openclaw_client)
+    assert stats["requeued_tasks"] == 1
+
+    # Verify task failed and new task created
+    db_session.refresh(task)
+    assert task.status == "failed"
+
+    new_task = db_session.exec(
+        select(IntelligentEvalTaskQueueDB).where(
+            IntelligentEvalTaskQueueDB.eval_id == "eval-1",
+            IntelligentEvalTaskQueueDB.status == "pending",
+        )
+    ).first()
+    assert new_task is not None
+    assert new_task.reason == "cron_inactive_retry"
+
+
+async def test_recover_from_platform_restart(db_session: Session, mock_openclaw_client):
+    """Test recovery from platform restart."""
+    # Create task assigned to inactive cron
+    task = IntelligentEvalTaskQueueDB(
+        eval_id="eval-1",
+        status="assigned",
+        priority=1,
+        reason="slot_due",
+        assigned_cron_id="inactive-cron",
+    )
+    db_session.add(task)
+    db_session.commit()
+
+    mock_openclaw_client.list_crons = AsyncMock(return_value=[])
+
+    stats = await fault_tolerance.recover_from_platform_restart(db_session, mock_openclaw_client)
+    assert stats["assigned_tasks_checked"] == 1
+    assert stats["requeued_tasks"] == 1
+
+    # Verify task requeued
+    new_task = db_session.exec(
+        select(IntelligentEvalTaskQueueDB).where(
+            IntelligentEvalTaskQueueDB.eval_id == "eval-1",
+            IntelligentEvalTaskQueueDB.status == "pending",
+        )
+    ).first()
+    assert new_task is not None
+    assert new_task.reason == "platform_restart_retry"
+
+
+async def test_recover_from_openclaw_restart(db_session: Session, mock_openclaw_client):
+    """Test recovery from OpenClaw restart."""
+    from agenteval.intelligent_eval.openclaw_client import OpenClawCron
+
+    # Mock OpenClaw returning crons
+    mock_openclaw_client.list_crons = AsyncMock(
+        return_value=[
+            OpenClawCron(
+                id="recovered-cron",
+                name="worker-1",
+                schedule="* * * * *",
+                enabled=True,
+                state={"status": "idle"},
+            )
+        ]
+    )
+
+    stats = await fault_tolerance.recover_from_openclaw_restart(db_session, mock_openclaw_client)
+    assert stats["synced_crons"] == 1
+
+    # Verify cron synced to DB
+    cron = db_session.exec(
+        select(OpenClawCronPoolDB).where(OpenClawCronPoolDB.openclaw_cron_id == "recovered-cron")
+    ).first()
+    assert cron is not None