test(09-01): add failing tests for retention cleanup service

- Test cleanup deletes expired snapshots
- Test snapshots within retention window are kept
- Test deleted count is returned
- Test empty table handled gracefully

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

.planning/REQUIREMENTS.md

@@ -41,7 +41,7 @@
 - [x] **UI-01**: Device page shows Configuration History section below Remote Access
 - [x] **UI-02**: Timeline displays change entries with component, summary, and timestamp
 - [x] **UI-03**: Diff viewer shows unified diff with add/remove highlighting
-- [ ] **UI-04**: User can download snapshot as `router-{device_name}-{timestamp}.rsc`
+- [x] **UI-04**: User can download snapshot as `router-{device_name}-{timestamp}.rsc`
 
 ### Observability
 
@@ -90,7 +90,7 @@
 | UI-01 | Phase 7: Config History UI | Complete |
 | UI-02 | Phase 7: Config History UI | Complete |
 | UI-03 | Phase 8: Diff Viewer & Download | Complete |
-| UI-04 | Phase 8: Diff Viewer & Download | Pending |
+| UI-04 | Phase 8: Diff Viewer & Download | Complete |
 | OBS-01 | Phase 10: Audit & Observability | Pending |
 | OBS-02 | Phase 10: Audit & Observability | Pending |
 

.planning/STATE.md

@@ -3,15 +3,15 @@ gsd_state_version: 1.0
 milestone: v9.6
 milestone_name: milestone
 status: completed
-stopped_at: Completed 08-01-PLAN.md
+stopped_at: Completed 08-02-PLAN.md
-last_updated: "2026-03-13T04:21:58.035Z"
+last_updated: "2026-03-13T04:24:44.396Z"
-last_activity: 2026-03-13 -- Completed 07-01 config history UI timeline component
+last_activity: 2026-03-13 -- Completed 08-02 snapshot download
 progress:
   total_phases: 10
-  completed_phases: 7
+  completed_phases: 8
   total_plans: 12
-  completed_plans: 11
+  completed_plans: 12
-  percent: 100
+  percent: 92
 ---
 
 # Project State
@@ -25,12 +25,12 @@ See: .planning/PROJECT.md (updated 2026-03-12)
 
 ## Current Position
 
-Phase: 8 of 10 (Diff Viewer & Download)
+Phase: 8 of 10 (Diff Viewer & Download) -- COMPLETE
-Plan: 1 of 2 in current phase
+Plan: 2 of 2 in current phase
-Status: Plan 08-01 complete
+Status: Phase 08 complete
-Last activity: 2026-03-13 -- Completed 08-01 diff viewer component
+Last activity: 2026-03-13 -- Completed 08-02 snapshot download
 
-Progress: [█████████░] 92%
+Progress: [██████████] 100%
 
 ## Performance Metrics
 
@@ -59,6 +59,7 @@ Progress: [█████████░] 92%
 | Phase 06 P02 | 2min | 2 tasks | 3 files |
 | Phase 07 P01 | 3min | 2 tasks | 3 files |
 | Phase 08 P01 | 1min | 2 tasks | 3 files |
+| Phase 08 P02 | 1min | 1 tasks | 3 files |
 
 ## Accumulated Context
 
@@ -92,6 +93,7 @@ Recent decisions affecting current work:
 - [Phase 07]: 60s refetchInterval polling for near-real-time config change visibility
 - [Phase 08]: DiffViewer rendered inline above timeline (not modal) for context preservation
 - [Phase 08]: Line classification function for unified diff: +green, -red, @@blue, ---/+++ muted
+- [Phase 08]: Blob URL download pattern consistent with existing exportMyData and auditLogsApi.exportCsv patterns
 
 ### Pending Todos
 
@@ -103,6 +105,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-13T04:21:58.032Z
+Last session: 2026-03-13T04:24:44.393Z
-Stopped at: Completed 08-01-PLAN.md
+Stopped at: Completed 08-02-PLAN.md
 Resume file: None

backend/tests/test_retention_service.py

@@ -0,0 +1,128 @@
+"""Tests for retention cleanup service.
+
+Tests the cleanup_expired_snapshots function with mocked AdminAsyncSessionLocal
+and mocked settings.CONFIG_RETENTION_DAYS.
+"""
+
+import pytest
+from unittest.mock import AsyncMock, MagicMock, patch
+
+
+@pytest.mark.asyncio
+async def test_cleanup_deletes_expired_snapshots():
+    """Test 1: cleanup_expired_snapshots deletes snapshots with collected_at older than retention_days."""
+    from app.services.retention_service import cleanup_expired_snapshots
+
+    mock_session = AsyncMock()
+    mock_result = MagicMock()
+    mock_result.rowcount = 5
+    mock_session.execute = AsyncMock(return_value=mock_result)
+    mock_session.commit = AsyncMock()
+
+    mock_ctx = AsyncMock()
+    mock_ctx.__aenter__ = AsyncMock(return_value=mock_session)
+    mock_ctx.__aexit__ = AsyncMock(return_value=False)
+
+    with patch(
+        "app.services.retention_service.AdminAsyncSessionLocal",
+        return_value=mock_ctx,
+    ), patch(
+        "app.services.retention_service.settings",
+    ) as mock_settings:
+        mock_settings.CONFIG_RETENTION_DAYS = 90
+        count = await cleanup_expired_snapshots()
+
+    # Should execute the DELETE query
+    mock_session.execute.assert_called_once()
+    # Verify DELETE uses make_interval with the configured days
+    sql_text = str(mock_session.execute.call_args[0][0].text)
+    assert "make_interval" in sql_text
+    assert "DELETE" in sql_text
+    assert "router_config_snapshots" in sql_text
+    # Should commit
+    mock_session.commit.assert_called_once()
+    # Should return the deleted count
+    assert count == 5
+
+
+@pytest.mark.asyncio
+async def test_cleanup_keeps_snapshots_within_retention_window():
+    """Test 2: cleanup_expired_snapshots keeps snapshots within the retention window."""
+    from app.services.retention_service import cleanup_expired_snapshots
+
+    mock_session = AsyncMock()
+    mock_result = MagicMock()
+    mock_result.rowcount = 0  # No rows deleted means all within window
+    mock_session.execute = AsyncMock(return_value=mock_result)
+    mock_session.commit = AsyncMock()
+
+    mock_ctx = AsyncMock()
+    mock_ctx.__aenter__ = AsyncMock(return_value=mock_session)
+    mock_ctx.__aexit__ = AsyncMock(return_value=False)
+
+    with patch(
+        "app.services.retention_service.AdminAsyncSessionLocal",
+        return_value=mock_ctx,
+    ), patch(
+        "app.services.retention_service.settings",
+    ) as mock_settings:
+        mock_settings.CONFIG_RETENTION_DAYS = 90
+        count = await cleanup_expired_snapshots()
+
+    assert count == 0
+
+
+@pytest.mark.asyncio
+async def test_cleanup_returns_deleted_count():
+    """Test 3: cleanup_expired_snapshots returns count of deleted rows."""
+    from app.services.retention_service import cleanup_expired_snapshots
+
+    mock_session = AsyncMock()
+    mock_result = MagicMock()
+    mock_result.rowcount = 42
+    mock_session.execute = AsyncMock(return_value=mock_result)
+    mock_session.commit = AsyncMock()
+
+    mock_ctx = AsyncMock()
+    mock_ctx.__aenter__ = AsyncMock(return_value=mock_session)
+    mock_ctx.__aexit__ = AsyncMock(return_value=False)
+
+    with patch(
+        "app.services.retention_service.AdminAsyncSessionLocal",
+        return_value=mock_ctx,
+    ), patch(
+        "app.services.retention_service.settings",
+    ) as mock_settings:
+        mock_settings.CONFIG_RETENTION_DAYS = 30
+        count = await cleanup_expired_snapshots()
+
+    assert count == 42
+
+
+@pytest.mark.asyncio
+async def test_cleanup_handles_empty_table():
+    """Test 4: cleanup_expired_snapshots handles empty table (returns 0)."""
+    from app.services.retention_service import cleanup_expired_snapshots
+
+    mock_session = AsyncMock()
+    mock_result = MagicMock()
+    mock_result.rowcount = 0
+    mock_session.execute = AsyncMock(return_value=mock_result)
+    mock_session.commit = AsyncMock()
+
+    mock_ctx = AsyncMock()
+    mock_ctx.__aenter__ = AsyncMock(return_value=mock_session)
+    mock_ctx.__aexit__ = AsyncMock(return_value=False)
+
+    with patch(
+        "app.services.retention_service.AdminAsyncSessionLocal",
+        return_value=mock_ctx,
+    ), patch(
+        "app.services.retention_service.settings",
+    ) as mock_settings:
+        mock_settings.CONFIG_RETENTION_DAYS = 90
+        count = await cleanup_expired_snapshots()
+
+    assert count == 0
+    mock_session.execute.assert_called_once()
+    mock_session.commit.assert_called_once()