feat: model validation, calibration, and signal quality layer

- Migration 035: prediction_snapshots, prediction_outcomes, signal_evidence_links, model_metric_snapshots tables + SQL views
- Prediction snapshot writer with canonical evidence keys, duplicate detection, contribution scores
- Outcome evaluator across 5 horizons (1h, 6h, 1d, 7d, 30d)
- Metrics engine: ECE, Brier score, IC, Rank IC, benchmark comparison
- Attribution engine: per-source, per-catalyst, per-layer performance
- Calibration engine: Bayesian shrinkage source reliability
- Quality gate for live trading eligibility with configurable thresholds
- 7 new /api/validation/* endpoints
- Upgraded OpsModel dashboard with validation tab
- Enhanced recommendation display with calibration context
- Backtest replay validation mode
- 86 Python tests (unit + property-based), 179 frontend tests passing

frontend/src/test/pages.test.tsx

@@ -169,6 +169,55 @@ describe('Global Events page', () => {
   });
 });
 
+describe('OpsModel validation tab', () => {
+  it('renders Model Validation tab with summary cards', async () => {
+    renderRoute('/ops/model');
+    await waitFor(() => expect(screen.getByText('Model Performance')).toBeInTheDocument());
+
+    // The tab buttons should be present
+    expect(screen.getByText('Extraction Performance')).toBeInTheDocument();
+    expect(screen.getByText('Model Validation')).toBeInTheDocument();
+
+    // Click the Model Validation tab button
+    await userEvent.click(screen.getByText('Model Validation'));
+
+    // Summary cards should render key metric labels unique to the validation summary
+    await waitFor(() => {
+      expect(screen.getByText('Brier Score')).toBeInTheDocument();
+      expect(screen.getByText('ECE')).toBeInTheDocument();
+      expect(screen.getByText('Directional Accuracy')).toBeInTheDocument();
+      expect(screen.getByText('Excess vs SPY')).toBeInTheDocument();
+    });
+  }, 10000);
+
+  it('renders calibration table with miscalibration warning', async () => {
+    renderRoute('/ops/model');
+    await waitFor(() => expect(screen.getByText('Model Performance')).toBeInTheDocument());
+
+    await userEvent.click(screen.getByText('Model Validation'));
+
+    await waitFor(() => {
+      expect(screen.getByText('Calibration by Confidence Bucket')).toBeInTheDocument();
+    });
+
+    // Miscalibrated buckets should show warning text
+    const miscalWarnings = screen.getAllByText('Miscalibrated');
+    expect(miscalWarnings.length).toBeGreaterThanOrEqual(1);
+  }, 10000);
+
+  it('renders gate status pass/fail indicator', async () => {
+    renderRoute('/ops/model');
+    await waitFor(() => expect(screen.getByText('Model Performance')).toBeInTheDocument());
+
+    await userEvent.click(screen.getByText('Model Validation'));
+
+    // The gate-status endpoint returns passed: false
+    await waitFor(() => {
+      expect(screen.getByText(/Live Trading Gate: FAIL/)).toBeInTheDocument();
+    });
+  }, 10000);
+});
+
 describe('Agents page', () => {
   it('renders agent list in sidebar', async () => {
     renderRoute('/agents');