fix: make qa config apply retries idempotent

extensions/qa-lab/src/suite-runtime-gateway.test.ts

@@ -1,6 +1,7 @@
 import { describe, expect, it } from "vitest";
 import {
   getGatewayRetryAfterMs,
+  isConfigApplyNoopForSnapshot,
   isConfigHashConflict,
   isConfigPatchNoopForSnapshot,
 } from "./suite-runtime-gateway.js";
@@ -62,4 +63,54 @@ describe("qa suite gateway helpers", () => {
       ),
     ).toBe(false);
   });
+
+  it("detects full config applies that only differ by gateway-written metadata", () => {
+    const config = {
+      gateway: {
+        controlUi: {
+          allowedOrigins: ["http://127.0.0.1:5173"],
+        },
+      },
+      meta: {
+        updatedAt: "2026-04-25T10:00:00.000Z",
+      },
+    };
+
+    expect(
+      isConfigApplyNoopForSnapshot(
+        config,
+        JSON.stringify({
+          gateway: {
+            controlUi: {
+              allowedOrigins: ["http://127.0.0.1:5173"],
+            },
+          },
+        }),
+      ),
+    ).toBe(true);
+  });
+
+  it("keeps changed full config applies eligible for the gateway", () => {
+    expect(
+      isConfigApplyNoopForSnapshot(
+        {
+          gateway: {
+            controlUi: {
+              allowedOrigins: ["http://127.0.0.1:5173"],
+            },
+          },
+          meta: {
+            updatedAt: "2026-04-25T10:00:00.000Z",
+          },
+        },
+        JSON.stringify({
+          gateway: {
+            controlUi: {
+              allowedOrigins: ["http://127.0.0.1:5174"],
+            },
+          },
+        }),
+      ),
+    ).toBe(false);
+  });
 });

extensions/qa-lab/src/suite-runtime-gateway.ts

@@ -178,6 +178,32 @@ function areJsonValuesEqual(left: unknown, right: unknown): boolean {
   return false;
 }
 
+function withoutQaConfigApplyVolatileFields(
+  config: Record<string, unknown>,
+): Record<string, unknown> {
+  const comparable = structuredClone(config);
+  // config.apply updates root metadata on write. Retries should not turn a
+  // completed apply into a metadata-only write/restart loop.
+  delete comparable.meta;
+  return comparable;
+}
+
+function isConfigApplyNoopForSnapshot(config: Record<string, unknown>, raw: string): boolean {
+  let nextConfig: unknown;
+  try {
+    nextConfig = JSON.parse(raw);
+  } catch {
+    return false;
+  }
+  if (!isPlainObject(nextConfig)) {
+    return false;
+  }
+  return areJsonValuesEqual(
+    withoutQaConfigApplyVolatileFields(config),
+    withoutQaConfigApplyVolatileFields(nextConfig),
+  );
+}
+
 function isConfigPatchNoopForSnapshot(config: Record<string, unknown>, raw: string): boolean {
   let patch: unknown;
   try {
@@ -233,6 +259,12 @@ async function runConfigMutation(params: {
       // control-plane write budget and making later capability checks flaky.
       return { ok: true, noop: true };
     }
+    if (
+      params.action === "config.apply" &&
+      isConfigApplyNoopForSnapshot(snapshot.config, params.raw)
+    ) {
+      return { ok: true, noop: true };
+    }
     try {
       const result = await params.env.gateway.call(
         params.action,
@@ -327,6 +359,7 @@ export {
   fetchJson,
   formatGatewayPrimaryErrorText,
   getGatewayRetryAfterMs,
+  isConfigApplyNoopForSnapshot,
   isConfigPatchNoopForSnapshot,
   isConfigHashConflict,
   isGatewayRestartRace,