feat(dashboard): aggregation service build_dashboard

Task 1 of #583. build_dashboard(user_id) assembles the /dashboard payload:
most-recently-active projects (ranked by max child updated_at) each broken
into active milestones -> open tasks (in_progress->priority->recency, capped 5),
recently-completed (7d/8), upcoming events (7d), week stats. Owner-scoped,
trashed excluded; each section isolated via _safe so one failure doesn't blank
the page.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_services_dashboard.py

@@ -0,0 +1,66 @@
+"""build_dashboard composition + helpers (services/dashboard.py).
+
+Query semantics (ranking/caps/owner-scope) are exercised by manual smoke —
+the repo's unit tests mock the DB, so SQL isn't executed here. These cover the
+pure helpers and the section-isolation contract.
+"""
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+
+def test_task_row_maps_fields():
+    from fabledassistant.services.dashboard import _task_row
+    n = MagicMock()
+    n.id = 5
+    n.title = "Wire reminders"
+    n.status = "in_progress"
+    n.priority = None
+    assert _task_row(n) == {
+        "id": 5, "title": "Wire reminders", "status": "in_progress", "priority": "none",
+    }
+
+
+@pytest.mark.asyncio
+async def test_safe_returns_value_then_empty_on_error():
+    from fabledassistant.services.dashboard import _safe
+
+    async def ok():
+        return [1, 2, 3]
+
+    async def boom():
+        raise RuntimeError("section blew up")
+
+    assert await _safe(ok(), []) == [1, 2, 3]
+    # a failing section returns the supplied empty default, not an exception
+    assert await _safe(boom(), []) == []
+    assert await _safe(boom(), {}) == {}
+
+
+@pytest.mark.asyncio
+async def test_build_dashboard_composes_sections():
+    import fabledassistant.services.dashboard as dash
+    with patch.object(dash, "_active_projects", AsyncMock(return_value=["P"])), \
+         patch.object(dash, "_recently_completed", AsyncMock(return_value=["done"])), \
+         patch.object(dash, "_upcoming_events", AsyncMock(return_value=["evt"])), \
+         patch.object(dash, "_week_stats", AsyncMock(return_value={"open_total": 4})):
+        out = await dash.build_dashboard(user_id=1)
+    assert out == {
+        "active_projects": ["P"],
+        "recently_completed": ["done"],
+        "upcoming_events": ["evt"],
+        "week_stats": {"open_total": 4},
+    }
+
+
+@pytest.mark.asyncio
+async def test_build_dashboard_isolates_failing_section():
+    import fabledassistant.services.dashboard as dash
+    with patch.object(dash, "_active_projects", AsyncMock(side_effect=RuntimeError("db down"))), \
+         patch.object(dash, "_recently_completed", AsyncMock(return_value=["done"])), \
+         patch.object(dash, "_upcoming_events", AsyncMock(return_value=[])), \
+         patch.object(dash, "_week_stats", AsyncMock(return_value={})):
+        out = await dash.build_dashboard(user_id=1)
+    # failing section degrades to its empty default; others still populate
+    assert out["active_projects"] == []
+    assert out["recently_completed"] == ["done"]