diff --git a/src/lib/guardrails/piiMasker.ts b/src/lib/guardrails/piiMasker.ts
index 20d4e59bce86..cb3b77f9564a 100644
--- a/src/lib/guardrails/piiMasker.ts
+++ b/src/lib/guardrails/piiMasker.ts
@@ -1,6 +1,7 @@
 import { BaseGuardrail, type GuardrailContext, type GuardrailResult } from "./base";
 import { processPII } from "@/shared/utils/inputSanitizer";
 import { sanitizePII, sanitizePIIResponse } from "@/lib/piiSanitizer";
+
 import { isFeatureFlagEnabled } from "@/shared/utils/featureFlags";
 
 type PiiDetection = {
@@ -11,7 +12,8 @@ type PiiDetection = {
 type JsonRecord = Record<string, unknown>;
 
 function isRequestPiiMaskingEnabled() {
-  // Request PII redaction is controlled by PII_REDACTION_ENABLED feature flag (DB settings override env var)
+  // Request PII redaction is controlled by PII_REDACTION_ENABLED feature flag (DB > env > default).
+  // INPUT_SANITIZER_MODE only governs prompt-injection policy (warn/block/log).
   return isFeatureFlagEnabled("PII_REDACTION_ENABLED");
 }
 
diff --git a/tests/unit/guardrails-registry.test.ts b/tests/unit/guardrails-registry.test.ts
index bb3e48590a11..a91f89d9bf6c 100644
--- a/tests/unit/guardrails-registry.test.ts
+++ b/tests/unit/guardrails-registry.test.ts
@@ -176,13 +176,42 @@ test("pii masker guardrail redacts request and response payloads", async () => {
       const postBody = postCall?.modifiedResponse as ChatLikePayload;
       const redactedContent = String(postBody.choices?.[0]?.message?.content);
       assert.ok(
-        redactedContent.includes("[EMAIL_REDACTED]") || redactedContent.includes("[PHONE_REDACTED]"),
+        redactedContent.includes("[EMAIL_REDACTED]") ||
+          redactedContent.includes("[PHONE_REDACTED]"),
         "email or phone should be redacted in response"
       );
     }
   );
 });
 
+test("pii masker respects feature flag overrides (DB and env)", async () => {
+  const { setFeatureFlagOverride, removeFeatureFlagOverride } =
+    await import("@/lib/db/featureFlags");
+
+  await withEnv(
+    {
+      PII_REDACTION_ENABLED: undefined,
+    },
+    async () => {
+      try {
+        setFeatureFlagOverride("PII_REDACTION_ENABLED", "true");
+        const guardrail = new PIIMaskerGuardrail();
+        const preCall = await guardrail.preCall({
+          messages: [{ role: "user", content: "Email me at dev@example.com" }],
+        });
+        assert.ok(
+          preCall?.modifiedPayload,
+          "DB override for PII_REDACTION_ENABLED=true should enable request redaction"
+        );
+        const preBody = preCall?.modifiedPayload as ChatLikePayload;
+        assert.match(String(preBody.messages?.[0]?.content), /\[EMAIL_REDACTED\]/);
+      } finally {
+        removeFeatureFlagOverride("PII_REDACTION_ENABLED");
+      }
+    }
+  );
+});
+
 test("pii masker does not rewrite request PII when redaction flag is off", async () => {
   await withEnv(
     {
@@ -200,7 +229,6 @@ test("pii masker does not rewrite request PII when redaction flag is off", async
   );
 });
 
-
 test("guardrail registry fails open when a guardrail throws", async () => {
   class ExplodingGuardrail extends BaseGuardrail {
     constructor() {