feat(audit): add guard-coverage thresholds to canary gate

src/audit/backendCanarySummary.test.ts

@@ -206,6 +206,52 @@ describe('summarizeBackendCanary', () => {
       { category: 'pi_module_interface', count: 1, pct: 50 },
     ]);
   });
+
+  it('tracks forced-native guard reasons', () => {
+    const events: AuditEvent[] = [
+      makeEvent(1000, 'backend.route', {
+        session_id: 's1',
+        channel: 'telegram',
+        sender: '1',
+        selected_backend: 'native',
+        source: 'forced_native_guard',
+        guard_reason: 'pi_no_tools_mode',
+      }),
+      makeEvent(1010, 'session.message', {
+        session_id: 's1',
+        role: 'assistant',
+        content_length: 10,
+      }),
+      makeEvent(2000, 'backend.route', {
+        session_id: 's2',
+        channel: 'telegram',
+        sender: '2',
+        selected_backend: 'native',
+        source: 'forced_native_guard',
+        guard_reason: 'capability_query',
+      }),
+      makeEvent(2010, 'session.message', {
+        session_id: 's2',
+        role: 'assistant',
+        content_length: 10,
+      }),
+    ];
+
+    const summary = summarizeBackendCanary(events, {
+      targetBackend: 'pi_embedded',
+      baselineBackend: 'native',
+    });
+
+    expect(summary.route_stats.forced_native_guards.pi_no_tools_mode).toBe(1);
+    expect(summary.route_stats.forced_native_guards.capability_query).toBe(1);
+
+    const markdown = renderBackendCanaryMarkdown(summary, {
+      targetBackend: 'pi_embedded',
+      baselineBackend: 'native',
+    });
+    expect(markdown).toContain('Forced Native Guards');
+    expect(markdown).toContain('pi_no_tools_mode');
+  });
 });
 
 describe('evaluateBackendCanaryGate', () => {
@@ -322,4 +368,65 @@ describe('evaluateBackendCanaryGate', () => {
       actual: '1',
     }));
   });
+
+  it('evaluates guard coverage thresholds', () => {
+    const events: AuditEvent[] = [
+      makeEvent(1000, 'backend.route', {
+        session_id: 's1',
+        channel: 'telegram',
+        sender: '1',
+        selected_backend: 'native',
+        source: 'forced_native_guard',
+        guard_reason: 'pi_no_tools_mode',
+      }),
+      makeEvent(1010, 'session.message', {
+        session_id: 's1',
+        role: 'assistant',
+        content_length: 20,
+      }),
+      makeEvent(2000, 'backend.route', {
+        session_id: 's2',
+        channel: 'telegram',
+        sender: '2',
+        selected_backend: 'native',
+        source: 'forced_native_guard',
+        guard_reason: 'attachments_present',
+      }),
+      makeEvent(2010, 'session.message', {
+        session_id: 's2',
+        role: 'assistant',
+        content_length: 20,
+      }),
+    ];
+
+    const summary = summarizeBackendCanary(events, {
+      targetBackend: 'pi_embedded',
+      baselineBackend: 'native',
+    });
+
+    const gate = evaluateBackendCanaryGate(summary, {
+      minGuardPiNoToolsCount: 1,
+      minGuardCapabilityQueryCount: 1,
+      minGuardAttachmentsPresentCount: 1,
+    });
+
+    expect(gate.pass).toBe(false);
+    expect(gate.criteria).toEqual([
+      expect.objectContaining({
+        criterion: 'Minimum pi_no_tools_mode guard hits',
+        pass: true,
+        actual: '1',
+      }),
+      expect.objectContaining({
+        criterion: 'Minimum capability_query guard hits',
+        pass: false,
+        actual: '0',
+      }),
+      expect.objectContaining({
+        criterion: 'Minimum attachments_present guard hits',
+        pass: true,
+        actual: '1',
+      }),
+    ]);
+  });
 });

src/audit/backendCanarySummary.ts

@@ -81,6 +81,9 @@ export interface BackendCanaryGateThresholds {
   minTargetRoutes?: number;
   minBaselineRoutes?: number;
   minTargetAttempts?: number;
+  minGuardPiNoToolsCount?: number;
+  minGuardCapabilityQueryCount?: number;
+  minGuardAttachmentsPresentCount?: number;
   maxCompletionRateDropPp?: number;
   maxP50LatencyIncreaseMs?: number;
   maxP95LatencyIncreaseMs?: number;
@@ -513,6 +516,36 @@ export function evaluateBackendCanaryGate(
     });
   }
 
+  if (typeof thresholds.minGuardPiNoToolsCount === 'number') {
+    const count = summary.route_stats.forced_native_guards.pi_no_tools_mode ?? 0;
+    criteria.push({
+      criterion: 'Minimum pi_no_tools_mode guard hits',
+      pass: count >= thresholds.minGuardPiNoToolsCount,
+      actual: `${count}`,
+      threshold: `>= ${thresholds.minGuardPiNoToolsCount}`,
+    });
+  }
+
+  if (typeof thresholds.minGuardCapabilityQueryCount === 'number') {
+    const count = summary.route_stats.forced_native_guards.capability_query ?? 0;
+    criteria.push({
+      criterion: 'Minimum capability_query guard hits',
+      pass: count >= thresholds.minGuardCapabilityQueryCount,
+      actual: `${count}`,
+      threshold: `>= ${thresholds.minGuardCapabilityQueryCount}`,
+    });
+  }
+
+  if (typeof thresholds.minGuardAttachmentsPresentCount === 'number') {
+    const count = summary.route_stats.forced_native_guards.attachments_present ?? 0;
+    criteria.push({
+      criterion: 'Minimum attachments_present guard hits',
+      pass: count >= thresholds.minGuardAttachmentsPresentCount,
+      actual: `${count}`,
+      threshold: `>= ${thresholds.minGuardAttachmentsPresentCount}`,
+    });
+  }
+
   if (typeof thresholds.maxCompletionRateDropPp === 'number') {
     const delta = summary.comparison.completion_rate_delta_pp;
     const pass = delta !== null && delta >= (-thresholds.maxCompletionRateDropPp);
@@ -600,6 +633,20 @@ export function renderBackendCanaryMarkdown(
   }
   lines.push('');
 
+  lines.push('### Forced Native Guards');
+  lines.push('');
+  lines.push('| Guard reason | Count |');
+  lines.push('| --- | ---: |');
+  const guardRows = Object.entries(summary.route_stats.forced_native_guards)
+    .sort((a, b) => b[1] - a[1] || a[0].localeCompare(b[0]));
+  for (const [reason, count] of guardRows) {
+    lines.push(`| ${reason} | ${count} |`);
+  }
+  if (guardRows.length === 0) {
+    lines.push('| _none_ | 0 |');
+  }
+  lines.push('');
+
   lines.push('## Reliability');
   lines.push('');
   lines.push('| Metric | Target | Baseline | Delta |');