feat(metrics): Implement dashboard metrics API and integrate metrics chart components

backend/app/schemas/__init__.py

@@ -1,6 +1,7 @@
 from app.schemas.activity_events import ActivityEventRead
 from app.schemas.agents import AgentCreate, AgentRead, AgentUpdate
 from app.schemas.boards import BoardCreate, BoardRead, BoardUpdate
+from app.schemas.metrics import DashboardMetrics
 from app.schemas.tasks import TaskCreate, TaskRead, TaskUpdate
 from app.schemas.users import UserCreate, UserRead, UserUpdate
 
@@ -12,6 +13,7 @@ __all__ = [
     "BoardCreate",
     "BoardRead",
     "BoardUpdate",
+    "DashboardMetrics",
     "TaskCreate",
     "TaskRead",
     "TaskUpdate",

backend/app/schemas/metrics.py

@@ -0,0 +1,57 @@
+from __future__ import annotations
+
+from datetime import datetime
+from typing import Literal
+
+from sqlmodel import SQLModel
+
+
+class DashboardSeriesPoint(SQLModel):
+    period: datetime
+    value: float
+
+
+class DashboardWipPoint(SQLModel):
+    period: datetime
+    inbox: int
+    in_progress: int
+    review: int
+
+
+class DashboardRangeSeries(SQLModel):
+    range: Literal["24h", "7d"]
+    bucket: Literal["hour", "day"]
+    points: list[DashboardSeriesPoint]
+
+
+class DashboardWipRangeSeries(SQLModel):
+    range: Literal["24h", "7d"]
+    bucket: Literal["hour", "day"]
+    points: list[DashboardWipPoint]
+
+
+class DashboardSeriesSet(SQLModel):
+    primary: DashboardRangeSeries
+    comparison: DashboardRangeSeries
+
+
+class DashboardWipSeriesSet(SQLModel):
+    primary: DashboardWipRangeSeries
+    comparison: DashboardWipRangeSeries
+
+
+class DashboardKpis(SQLModel):
+    active_agents: int
+    tasks_in_progress: int
+    error_rate_pct: float
+    median_cycle_time_hours_7d: float | None
+
+
+class DashboardMetrics(SQLModel):
+    range: Literal["24h", "7d"]
+    generated_at: datetime
+    kpis: DashboardKpis
+    throughput: DashboardSeriesSet
+    cycle_time: DashboardSeriesSet
+    error_rate: DashboardSeriesSet
+    wip: DashboardWipSeriesSet