## WS3: Advanced Analytics Dashboard

### Purpose

Give paying tenants actionable visibility into their agent usage patterns. Analytics surface four dimensions: agent activity over time (heatmap), token issuance frequency and volume (trends), credential rotation frequency (rotation frequency table), and per-endpoint API call patterns (call patterns breakdown). Data is pre-aggregated nightly from the existing `usage_events` table into a new `analytics_daily_aggregates` table. Analytics are rendered in a new Analytics tab in the existing React web dashboard.

### New Endpoints

#### `GET /analytics/usage-summary`

**Summary:** Return a high-level usage summary for the authenticated tenant over a date range.

**Authentication:** Bearer token (tenant-scoped).

**Query Parameters:**

| Parameter | Type | Required | Default | Constraints |
|---|---|---|---|---|
| `from` | string (YYYY-MM-DD) | no | 30 days ago | Must be <= `to` |
| `to` | string (YYYY-MM-DD) | no | today | Must be <= today |

**Response 200** (`application/json`):
```json
{
  "tenantId": "string (UUID)",
  "period": {
    "from": "string (YYYY-MM-DD)",
    "to": "string (YYYY-MM-DD)"
  },
  "summary": {
    "totalApiCalls": 84320,
    "totalTokenIssuances": 12400,
    "totalCredentialRotations": 48,
    "activeAgentCount": 23,
    "averageDailyApiCalls": 2810,
    "peakDailyApiCalls": 5102,
    "peakDate": "2026-03-28"
  }
}
```

**Error Responses:**

| Status | Code | Description |
|---|---|---|
| 400 | `INVALID_DATE_RANGE` | `from` > `to`, or date range exceeds 365 days |
| 401 | `UNAUTHORIZED` | Missing or invalid Bearer token |
| 403 | `ANALYTICS_NOT_AVAILABLE` | Tenant is on free tier — analytics require Pro or Enterprise |
| 429 | `RATE_LIMITED` | Rate limit exceeded |

---

#### `GET /analytics/agent-activity`

**Summary:** Return per-agent daily activity counts for heatmap rendering.

**Authentication:** Bearer token (tenant-scoped).

**Query Parameters:**

| Parameter | Type | Required | Default | Constraints |
|---|---|---|---|---|
| `from` | string (YYYY-MM-DD) | no | 30 days ago | Must be <= `to` |
| `to` | string (YYYY-MM-DD) | no | today | Max range: 90 days |
| `agentId` | string (UUID) | no | (all agents) | Filter to a single agent |

**Response 200** (`application/json`):
```json
{
  "tenantId": "string (UUID)",
  "period": {
    "from": "string (YYYY-MM-DD)",
    "to": "string (YYYY-MM-DD)"
  },
  "agents": [
    {
      "agentId": "string (UUID)",
      "agentName": "string",
      "dailyActivity": [
        {
          "date": "2026-03-01",
          "apiCalls": 342,
          "tokenIssuances": 12,
          "credentialRotations": 0
        }
      ]
    }
  ]
}
```

**Error Responses:**

| Status | Code | Description |
|---|---|---|
| 400 | `INVALID_DATE_RANGE` | `from` > `to`, or date range exceeds 90 days |
| 401 | `UNAUTHORIZED` | Missing or invalid Bearer token |
| 403 | `ANALYTICS_NOT_AVAILABLE` | Free tier — requires Pro or Enterprise |
| 404 | `AGENT_NOT_FOUND` | `agentId` filter specified but agent does not belong to tenant |
| 429 | `RATE_LIMITED` | Rate limit exceeded |

---

#### `GET /analytics/token-trends`

**Summary:** Return daily token issuance counts and success/failure breakdown for trend charts.

**Authentication:** Bearer token (tenant-scoped).

**Query Parameters:**

| Parameter | Type | Required | Default | Constraints |
|---|---|---|---|---|
| `from` | string (YYYY-MM-DD) | no | 30 days ago | Must be <= `to` |
| `to` | string (YYYY-MM-DD) | no | today | Max range: 365 days |
| `granularity` | string | no | `day` | Enum: `day`, `week` |

**Response 200** (`application/json`):
```json
{
  "tenantId": "string (UUID)",
  "period": {
    "from": "string (YYYY-MM-DD)",
    "to": "string (YYYY-MM-DD)"
  },
  "granularity": "day",
  "dataPoints": [
    {
      "date": "2026-03-01",
      "totalIssuances": 420,
      "successfulIssuances": 415,
      "failedIssuances": 5,
      "uniqueAgents": 8
    }
  ]
}
```

**Error Responses:**

| Status | Code | Description |
|---|---|---|
| 400 | `INVALID_DATE_RANGE` | `from` > `to`, or date range exceeds 365 days |
| 400 | `INVALID_GRANULARITY` | `granularity` is not `day` or `week` |
| 401 | `UNAUTHORIZED` | Missing or invalid Bearer token |
| 403 | `ANALYTICS_NOT_AVAILABLE` | Free tier — requires Pro or Enterprise |
| 429 | `RATE_LIMITED` | Rate limit exceeded |

---

### Database Schema Changes

#### Migration: `009_add_analytics_aggregates.sql`

```sql
CREATE TABLE analytics_daily_aggregates (
    id              UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    tenant_id       UUID NOT NULL REFERENCES tenants(id) ON DELETE CASCADE,
    agent_id        UUID REFERENCES agents(id) ON DELETE SET NULL,   -- NULL = tenant-wide aggregate
    date            DATE NOT NULL,
    metric_type     VARCHAR(64) NOT NULL,   -- 'api_calls' | 'token_issuances' | 'credential_rotations' | 'token_failures'
    count           BIGINT NOT NULL DEFAULT 0,
    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),

    CONSTRAINT uq_daily_aggregate UNIQUE (tenant_id, agent_id, date, metric_type)
);

-- Index for analytics queries (tenant + date range)
CREATE INDEX idx_analytics_tenant_date ON analytics_daily_aggregates(tenant_id, date);
CREATE INDEX idx_analytics_agent_date ON analytics_daily_aggregates(agent_id, date) WHERE agent_id IS NOT NULL;
```

#### Nightly Aggregation Job

A `node-cron` job runs at `00:05 UTC` daily inside the Express API process. It executes an upsert query aggregating the previous day's `usage_events` rows into `analytics_daily_aggregates`. The job is idempotent — running it twice for the same date produces no duplicates (upsert on the unique constraint).

Job logic (pseudocode):
```
1. Compute target_date = yesterday (UTC)
2. SELECT tenant_id, agent_id, metric_type, SUM(count)
   FROM usage_events
   WHERE date = target_date
   GROUP BY tenant_id, agent_id, metric_type
3. UPSERT INTO analytics_daily_aggregates
   ON CONFLICT (tenant_id, agent_id, date, metric_type)
   DO UPDATE SET count = EXCLUDED.count, updated_at = NOW()
```

### New Source Files

| File | Description |
|---|---|
| `src/services/AnalyticsService.ts` | Business logic: query aggregates, build response shapes, Redis caching |
| `src/controllers/AnalyticsController.ts` | HTTP handlers for analytics endpoints |
| `src/routes/analytics.ts` | Express router for `/analytics/` prefix |
| `src/jobs/analyticsAggregation.ts` | `node-cron` job that aggregates usage_events nightly |
| `src/types/analytics.ts` | TypeScript interfaces: `UsageSummary`, `AgentActivityResponse`, `TokenTrendsResponse`, `DailyAggregate` |
| `dashboard/src/pages/Analytics.tsx` | New Analytics tab in existing React dashboard |
| `dashboard/src/components/charts/AgentHeatmap.tsx` | Heatmap component using `recharts` `ResponsiveContainer` + custom cells |
| `dashboard/src/components/charts/TokenTrendsChart.tsx` | Line chart of token issuance over time using `recharts` `LineChart` |
| `dashboard/src/components/charts/RotationFrequencyTable.tsx` | Sortable table of credential rotation counts per agent |
| `dashboard/src/api/analyticsApi.ts` | Typed fetch functions for analytics endpoints |

### Modified Source Files

| File | Change |
|---|---|
| `src/app.ts` | Register `analytics` router; start nightly aggregation cron job |
| `src/infrastructure/migrations/` | Add `009_add_analytics_aggregates.sql` |
| `dashboard/src/App.tsx` | Add Analytics route and nav link |
| `package.json` (API) | Add `node-cron` dependency |
| `package.json` (dashboard) | Add `recharts`, `date-fns` dependencies |
| `docs/openapi.yaml` | Add analytics endpoints |

### Redis Caching

Analytics responses are cached in Redis with `analytics:{tenantId}:{endpoint}:{queryHash}` keys. TTL: 5 minutes for agent-activity and token-trends; 60 seconds for usage-summary. Cache is invalidated on the next request after TTL expiry (no explicit invalidation).

### `AnalyticsService` Interface

```typescript
interface IAnalyticsService {
    /**
     * Return a high-level usage summary for a tenant over a date range.
     */
    getUsageSummary(tenantId: string, from: Date, to: Date): Promise<UsageSummary>;

    /**
     * Return per-agent daily activity data for heatmap rendering.
     */
    getAgentActivity(
        tenantId: string,
        from: Date,
        to: Date,
        agentId?: string
    ): Promise<AgentActivityResponse>;

    /**
     * Return daily token issuance trends with success/failure breakdown.
     */
    getTokenTrends(
        tenantId: string,
        from: Date,
        to: Date,
        granularity: 'day' | 'week'
    ): Promise<TokenTrendsResponse>;
}
```

### Prometheus Metrics

| Metric | Type | Labels | Description |
|---|---|---|---|
| `agentidp_analytics_query_duration_ms` | Histogram | `endpoint` | Analytics query latency (before cache) |
| `agentidp_analytics_cache_hits_total` | Counter | `endpoint` | Analytics Redis cache hits |
| `agentidp_analytics_cache_misses_total` | Counter | `endpoint` | Analytics Redis cache misses |
| `agentidp_analytics_aggregation_job_duration_ms` | Gauge | — | Nightly aggregation job runtime |
| `agentidp_analytics_aggregation_job_last_run` | Gauge | — | Unix timestamp of last successful aggregation job run |

### Feature Flags

| Variable | Default | Description |
|---|---|---|
| `ANALYTICS_ENABLED` | `true` | When `false`, all `/analytics/` routes return HTTP 404 |
| `ANALYTICS_FREE_TIER` | `false` | When `true`, free tier tenants can access analytics (for beta/testing) |

### Acceptance Criteria

- `GET /analytics/usage-summary` returns correct aggregate counts for a date range
- `GET /analytics/agent-activity` returns per-agent daily rows matching `analytics_daily_aggregates`
- `GET /analytics/token-trends` returns daily and weekly granularity correctly
- All three endpoints return HTTP 403 for free-tier tenants (when `ANALYTICS_FREE_TIER=false`)
- Date range validation rejects `from > to` with HTTP 400
- Nightly aggregation job runs idempotently — running twice for same date produces no duplicates
- Analytics responses are cached in Redis — a second identical request does not hit the DB
- Dashboard Analytics tab renders heatmap, trend chart, and rotation table with mock data in Storybook
- Unit test coverage >= 80% on `AnalyticsService`
- Integration tests cover: summary, activity, trends (daily), trends (weekly), free-tier rejection, invalid date range