diff --git a/.github/workflows/performance-regression.yml b/.github/workflows/performance-regression.yml
new file mode 100644
index 0000000..f790770
--- /dev/null
+++ b/.github/workflows/performance-regression.yml
@@ -0,0 +1,32 @@
+name: Performance Regression Detection
+
+on:
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  performance-test:
+    runs-on: ubuntu-latest
+    services:
+      # If you need DBs (Postgres/Redis), define them here
+      postgres:
+        image: postgres:15
+        ports: ['5432:5432']
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Set up Environment
+        # Add steps to build your backend (npm install, go build, etc.)
+        run: |
+          npm install
+          npm run build
+          npm run start & 
+          sleep 10 # Wait for boot
+
+      - name: Run k6 Performance Test
+        uses: grafana/k6-action@v0.3.0
+        with:
+          filename: tests/performance/critical-paths.js
+          flags: --env API_URL=http://localhost:3000
diff --git a/src/audit-guard/src/policy-engine.test.ts b/src/audit-guard/src/policy-engine.test.ts
index 6e8aa9e..009cb66 100644
--- a/src/audit-guard/src/policy-engine.test.ts
+++ b/src/audit-guard/src/policy-engine.test.ts
@@ -452,6 +452,17 @@ describe("PolicyEngine", () => {
     });
   });
 
+  it("should return NON_COMPLIANT when bundle tampering is detected", async () => {
+  // Mock the verifier to return a BundleTampered error
+  // Mock the verifier.verify() to return { verified: false, errors: [{ code: 'BundleTampered', ... }] }
+  
+  const result = await engine.evaluate(mockPrData);
+  
+  expect(result.status).toBe("NON_COMPLIANT");
+  expect(result.violations_count).toBeGreaterThan(0);
+  expect(result.summary).toContain("tampering detected");
+});
+
   describe("Large Changes", () => {
     it("should warn about many files modified", async () => {
       const files = Array.from({ length: 25 }, (_, i) => `src/file${i}.ts`);
diff --git a/src/audit-guard/src/policy-engine.ts b/src/audit-guard/src/policy-engine.ts
index 701a800..454bd94 100644
--- a/src/audit-guard/src/policy-engine.ts
+++ b/src/audit-guard/src/policy-engine.ts
@@ -195,19 +195,17 @@ export class PolicyEngine {
     }
   }
 
-  /**
+ /**
    * Second, independent control against a compromised CI runner tampering with
-   * the Rego policy bundle (Issue #171 / VAG-003). When bundle signing is
-   * configured (POLICY_BUNDLE_SIGNATURE + POLICY_BUNDLE_SIGNERS), verify the
-   * on-disk bundle against a manifest signed offline by a trusted maintainer
-   * key. Observational-only: failures are surfaced as high/critical WARNINGS
-   * (which reportToDashboard() forwards as alerts) — they never silently drop,
-   * but this control holds no on-chain halt authority.
+   * the Rego policy bundle (Issue #171 / VAG-003). 
+   * 
+   * UPDATED (Issue #311): Confirmed tampering now promotes status to 
+   * NON_COMPLIANT to block the build.
    */
   private applyPolicyBundleVerification(result: EvaluationResult): void {
     const verifier = new PolicyBundleVerifier({ policiesDir: this.policiesDir });
     if (!verifier.isConfigured()) {
-      return; // Enforcement not enabled for this repo/environment.
+      return; 
     }
 
     const verification = verifier.verify();
@@ -215,25 +213,46 @@ export class PolicyEngine {
       return;
     }
 
+    let hasTampering = false;
+
     for (const err of verification.errors) {
-      const critical =
+      const isTampered =
         err.code === PolicyBundleErrorCode.BundleTampered ||
         err.code === PolicyBundleErrorCode.SignatureInvalid ||
         err.code === PolicyBundleErrorCode.UntrustedSigner;
-      result.warnings.push({
-        rule: err.code,
-        severity: critical ? "CRITICAL" : "HIGH",
-        message: `⚠️  Policy bundle signature verification failed: ${err.message}`,
-        detail: err.detail || err.message,
-      });
+
+      if (isTampered) {
+        hasTampering = true;
+        // Promote to violations to block build
+        result.violations.push({
+          rule: err.code,
+          severity: "CRITICAL",
+          message: `❌ CRITICAL: Policy bundle integrity check failed: ${err.message}`,
+          detail: err.detail || err.message,
+        });
+      } else {
+        // Keep non-critical verification issues as warnings
+        result.warnings.push({
+          rule: err.code,
+          severity: "HIGH",
+          message: `⚠️  Policy bundle signature verification warning: ${err.message}`,
+          detail: err.detail || err.message,
+        });
+      }
     }
 
+    // Update counts
+    result.violations_count = result.violations.length;
     result.warnings_count = result.warnings.length;
-    if (result.status === "COMPLIANT") {
+
+    // Determine final status
+    if (hasTampering) {
+      result.status = "NON_COMPLIANT";
+      result.summary = "❌ Policy bundle tampering detected — blocking build";
+    } else if (result.warnings.length > 0 && result.status === "COMPLIANT") {
       result.status = "WARNING";
     }
   }
-
   /**
    * Evaluate using OPA CLI
    */
diff --git a/tests/performance/critical-paths.js b/tests/performance/critical-paths.js
new file mode 100644
index 0000000..d56cbf0
--- /dev/null
+++ b/tests/performance/critical-paths.js
@@ -0,0 +1,30 @@
+import http from 'k6/http';
+import { check, sleep } from 'k6';
+
+export const options = {
+  thresholds: {
+    // CRITICAL: Fail if 99% of requests take longer than 100ms
+    http_req_duration: ['p(99)<100'], 
+    // Ensure availability target
+    http_req_failed: ['rate<0.01'], 
+  },
+  stages: [
+    { duration: '1m', target: 50 }, // Ramp up to 50 users
+    { duration: '3m', target: 50 }, // Stay at 50 users
+    { duration: '1m', target: 0 },  // Ramp down
+  ],
+};
+
+export default function () {
+  const params = {
+    headers: { 'Content-Type': 'application/json' },
+  };
+
+  const responses = http.batch([
+    ['GET', `${__ENV.API_URL}/v1/status`, null, params],
+    ['GET', `${__ENV.API_URL}/v1/node/verify`, null, params],
+  ]);
+
+  check(responses[0], { 'status is 200': (r) => r.status === 200 });
+  sleep(1);
+}