diff --git a/packages/gateway-protocol/package.json b/packages/gateway-protocol/package.json
index 5a997f7d2fba..679ac1709446 100644
--- a/packages/gateway-protocol/package.json
+++ b/packages/gateway-protocol/package.json
@@ -78,8 +78,7 @@
     "prepack": "pnpm run build && node --import tsx ../../scripts/protocol-gen.ts --out ./protocol.schema.json"
   },
   "dependencies": {
-    "typebox": "1.3.6",
-    "zod": "4.4.3"
+    "typebox": "1.3.6"
   },
   "engines": {
     "node": ">=22.19.0"
diff --git a/packages/gateway-protocol/src/install-policy-warning-error-details.ts b/packages/gateway-protocol/src/install-policy-warning-error-details.ts
index 4da07ceccea4..452b46d78938 100644
--- a/packages/gateway-protocol/src/install-policy-warning-error-details.ts
+++ b/packages/gateway-protocol/src/install-policy-warning-error-details.ts
@@ -1,4 +1,7 @@
-import { z } from "zod";
+import {
+  asProtocolRecord,
+  normalizeOptionalProtocolString,
+} from "./protocol-value-normalization.js";
 
 /** Structured install-policy warning details carried in Gateway error payloads. */
 export const INSTALL_POLICY_WARNING_ACKNOWLEDGEMENT_REQUIRED =
@@ -23,28 +26,84 @@ export type InstallPolicyWarningErrorDetails = {
   findings?: InstallPolicyWarningErrorFinding[];
 };
 
-const installPolicyWarningFindingSchema = z.object({
-  ruleId: z.string().trim().min(1),
-  severity: z.enum(["info", "warn", "critical"]),
-  message: z.string().trim().min(1),
-  file: z.string().trim().min(1).optional(),
-  line: z.number().int().positive().optional(),
-  evidence: z.string().trim().min(1).optional(),
-});
-
-const installPolicyWarningErrorDetailsSchema = z.object({
-  installPolicyCode: z.literal(INSTALL_POLICY_WARNING_ACKNOWLEDGEMENT_REQUIRED),
-  targetName: z.string().trim().min(1),
-  targetType: z.enum(["skill", "plugin"]),
-  requestMode: z.enum(["install", "update"]),
-  reason: z.string().trim().min(1),
-  acknowledgementToken: z.string().trim().min(1),
-  findings: z.array(installPolicyWarningFindingSchema).optional(),
-});
+function readFinding(value: unknown): InstallPolicyWarningErrorFinding | undefined {
+  const record = asProtocolRecord(value);
+  if (!record) {
+    return undefined;
+  }
+  const ruleId = normalizeOptionalProtocolString(record.ruleId);
+  const message = normalizeOptionalProtocolString(record.message);
+  const severity = record.severity;
+  if (
+    !ruleId ||
+    !message ||
+    (severity !== "info" && severity !== "warn" && severity !== "critical")
+  ) {
+    return undefined;
+  }
+  const file = normalizeOptionalProtocolString(record.file);
+  const evidence = normalizeOptionalProtocolString(record.evidence);
+  const line = record.line;
+  if (
+    (record.file !== undefined && !file) ||
+    (record.evidence !== undefined && !evidence) ||
+    (line !== undefined && (typeof line !== "number" || !Number.isSafeInteger(line) || line <= 0))
+  ) {
+    return undefined;
+  }
+  return {
+    ruleId,
+    severity,
+    message,
+    ...(file ? { file } : {}),
+    ...(line !== undefined ? { line } : {}),
+    ...(evidence ? { evidence } : {}),
+  };
+}
 
 export function readInstallPolicyWarningErrorDetails(
   value: unknown,
 ): InstallPolicyWarningErrorDetails | undefined {
-  const parsed = installPolicyWarningErrorDetailsSchema.safeParse(value);
-  return parsed.success ? parsed.data : undefined;
+  const record = asProtocolRecord(value);
+  if (!record) {
+    return undefined;
+  }
+  const targetName = normalizeOptionalProtocolString(record.targetName);
+  const reason = normalizeOptionalProtocolString(record.reason);
+  const acknowledgementToken = normalizeOptionalProtocolString(record.acknowledgementToken);
+  const targetType = record.targetType;
+  const requestMode = record.requestMode;
+  if (
+    record.installPolicyCode !== INSTALL_POLICY_WARNING_ACKNOWLEDGEMENT_REQUIRED ||
+    !targetName ||
+    !reason ||
+    !acknowledgementToken ||
+    (targetType !== "skill" && targetType !== "plugin") ||
+    (requestMode !== "install" && requestMode !== "update")
+  ) {
+    return undefined;
+  }
+  let findings: InstallPolicyWarningErrorFinding[] | undefined;
+  if (record.findings !== undefined) {
+    if (!Array.isArray(record.findings)) {
+      return undefined;
+    }
+    findings = [];
+    for (const value of record.findings) {
+      const finding = readFinding(value);
+      if (!finding) {
+        return undefined;
+      }
+      findings.push(finding);
+    }
+  }
+  return {
+    installPolicyCode: INSTALL_POLICY_WARNING_ACKNOWLEDGEMENT_REQUIRED,
+    targetName,
+    targetType,
+    requestMode,
+    reason,
+    acknowledgementToken,
+    ...(findings ? { findings } : {}),
+  };
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 985f8a3a0b04..dc69e89ec2b9 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -2231,9 +2231,6 @@ importers:
       typebox:
         specifier: 1.3.6
         version: 1.3.6
-      zod:
-        specifier: 4.4.3
-        version: 4.4.3
 
   packages/llm-core:
     dependencies:
diff --git a/src/gateway/install-policy-warning-error-details.test.ts b/src/gateway/install-policy-warning-error-details.test.ts
index 731616e3c38d..64ecdf1d5ac8 100644
--- a/src/gateway/install-policy-warning-error-details.test.ts
+++ b/src/gateway/install-policy-warning-error-details.test.ts
@@ -46,7 +46,30 @@ describe("install policy warning error details", () => {
       requestMode: "install",
       reason: "",
     },
+    {
+      ...expectedWarning,
+      findings: [{ ...completeWarning.findings?.[0], line: 0 }],
+    },
+    {
+      ...expectedWarning,
+      findings: [{ ...completeWarning.findings?.[0], severity: "error" }],
+    },
   ])("rejects malformed warning details", (value) => {
     expect(readInstallPolicyWarningErrorDetails(value)).toBeUndefined();
   });
+
+  it("normalizes protocol strings without changing the published dependency surface", () => {
+    expect(
+      readInstallPolicyWarningErrorDetails({
+        ...expectedWarning,
+        targetName: " demo-plugin ",
+        reason: " Review required ",
+        acknowledgementToken: " token ",
+      }),
+    ).toMatchObject({
+      targetName: "demo-plugin",
+      reason: "Review required",
+      acknowledgementToken: "token",
+    });
+  });
 });