diff --git a/backend/__tests__/unit/helm/litellmStagingEnabled.test.js b/backend/__tests__/unit/helm/litellmStagingEnabled.test.js
index 4b03a8de3e..8a8e9872ce 100644
--- a/backend/__tests__/unit/helm/litellmStagingEnabled.test.js
+++ b/backend/__tests__/unit/helm/litellmStagingEnabled.test.js
@@ -61,3 +61,18 @@ describe('staging LiteLLM is enabled so native-runtime agents (Scout) can answer
     expect(tol == null || (Array.isArray(tol) && tol.length === 0)).toBe(true);
   });
 });
+
+describe('staging native runtime runs injection-guard only (no real OpenAI moderation key)', () => {
+  test('nativeRuntimeGuardrails is injection-guard — matches prod', () => {
+    // The native runtime's default guardrail pair includes openai-moderation-enforce,
+    // which calls OpenAI's moderation API with OPENAI_API_KEY. Staging's openai-api-key is
+    // an 11-byte placeholder (as prod's was), so that guardrail returned HTTP 401 on EVERY
+    // native turn before the model call — the second half of the 2026-10-31 Scout-staging
+    // incident. injection-guard is LiteLLM-native (no key, no external service). If staging
+    // ever drops this override, enabling litellm alone will not make Scout answer.
+    expect(staging.backend.env.nativeRuntimeGuardrails).toBe('injection-guard');
+    // Prod carries the identical override; keep them in lockstep until a real OpenAI
+    // moderation key lands in the api-keys secret and both can restore the pair together.
+    expect(staging.backend.env.nativeRuntimeGuardrails).toBe(dev.backend.env.nativeRuntimeGuardrails);
+  });
+});
diff --git a/k8s/helm/commonly/values-staging.yaml b/k8s/helm/commonly/values-staging.yaml
index 83cd90dad6..e0149a4c20 100644
--- a/k8s/helm/commonly/values-staging.yaml
+++ b/k8s/helm/commonly/values-staging.yaml
@@ -160,6 +160,18 @@ litellm:
 
 backend:
   env:
+    # injection-guard ONLY — matches prod (values-dev.yaml). The native runtime's
+    # default guardrail pair (nativeRuntimeService.ts) includes openai-moderation-enforce,
+    # which calls OpenAI's moderation API with OPENAI_API_KEY. Staging's api-keys
+    # openai-api-key is an 11-byte placeholder (prod's is the literal "placeholder" too),
+    # so that guardrail 401'd on EVERY native turn BEFORE the model call — litellm logged
+    # 401 from https://api.openai.com/v1/moderations and returned HTTP 401 for
+    # deepseek-v4-flash. This was the second half of the 2026-10-31 Scout-staging incident:
+    # enabling litellm (above) fixed the missing-backend 401, this fixes the guardrail 401.
+    # injection-guard is LiteLLM-native (no key, no external service) and keeps the
+    # prompt-injection block. Restore the pair only after a real OpenAI moderation key
+    # lands in the staging api-keys secret. Guard test: litellmStagingEnabled.test.js.
+    nativeRuntimeGuardrails: "injection-guard"
     agentComputerEnabled: "true"
     agentComputerSteelApiUrlTemplate: "http://steel-{userId}.commonly-staging.svc.cluster.local:3000"
     agentComputerSteelCdpUrlTemplate: "http://steel-{userId}.commonly-staging.svc.cluster.local:9223"