diff --git a/src/server/responses/core.ts b/src/server/responses/core.ts
index c1ce136ca4..36a7d86a4d 100644
--- a/src/server/responses/core.ts
+++ b/src/server/responses/core.ts
@@ -4254,6 +4254,15 @@ async function handleResponsesInner(
       throw new Error("OAuth account selection changed repeatedly before dispatch");
     };
   };
+  const selectionBoundContinuationDispatch = (
+    wireRequest: AdapterRequest,
+  ): ProviderFetchOptions["dispatchOverride"] => async (input, init, execute) => {
+    if (!selectionIsCurrent(requestBindings.get(wireRequest))) {
+      throw new Error("API key selection changed during a request continuation");
+    }
+    const fetchImpl = (route.provider as OcxProviderConfig & { fetch?: typeof globalThis.fetch }).fetch ?? execute;
+    return fetchImpl(input, { ...init, redirect: "manual" });
+  };
   const anthropicSessionKey = route.providerName === "anthropic" && route.provider.authMode === "oauth"
     ? anthropicSessionKeyFromParts({
       sessionIdHeader: sessionIdHeaderFromRequest(req.headers),
@@ -5851,7 +5860,9 @@ async function handleResponsesInner(
             connectMs,
             true,
             providerFetch(route.provider, options.codexWsRuntimeIdentity, {
-              dispatchOverride: oauthDispatch(request),
+              // The first leg has already been served by this key. Unlike a pre-dispatch
+              // retry, a continuation must never rebuild the turn under a newly selected key.
+              dispatchOverride: selectionBoundContinuationDispatch(request),
               providerName: route.providerName,
               modelId: route.modelId,
             }),
diff --git a/tests/web-search/web-search-passthrough-bridge.test.ts b/tests/web-search/web-search-passthrough-bridge.test.ts
index 9e7029bb53..b26e791e27 100644
--- a/tests/web-search/web-search-passthrough-bridge.test.ts
+++ b/tests/web-search/web-search-passthrough-bridge.test.ts
@@ -572,6 +572,7 @@ describe("the reported turn, end to end through handleResponses", () => {
   async function post(
     ocxConfig: OcxConfig,
     legs: string[],
+    onSearch?: () => void,
   ): Promise<{ body: string; outbound: string[]; searches: number }> {
     const savedFetch = globalThis.fetch;
     const outbound: string[] = [];
@@ -583,6 +584,7 @@ describe("the reported turn, end to end through handleResponses", () => {
         : input instanceof URL ? input.href : (input as Request).url;
       if (url.includes("/api/web_search")) {
         searches += 1;
+        onSearch?.();
         return new Response(JSON.stringify({
           results: [{ title: "Releases", url: "https://example.test/rel", content: "opencodex 2.50.0" }],
         }), { headers: { "content-type": "application/json" } });
@@ -632,6 +634,20 @@ describe("the reported turn, end to end through handleResponses", () => {
       item.type === "function_call" && item.name === "web_search")).toBe(true);
   });
 
+  test("fails closed when the selected API key changes before a continuation", async () => {
+    const ocxConfig = config(armed);
+    const result = await post(ocxConfig, [searchLeg(), answerLeg()], () => {
+      ocxConfig.providers.fixture!.apiKey = "replacement-key";
+      ocxConfig.providers.fixture!.apiKeySelectionRevision = "replacement-selection";
+    });
+
+    expect(result.searches).toBe(1);
+    expect(result.outbound).toHaveLength(1);
+    expect(result.outbound[0]).toContain("what is the latest release?");
+    expect(result.body).toContain(WEB_SEARCH_BRIDGE_ERROR_CODE);
+    expect(result.body).not.toContain("The current release is 2.50.0.");
+  });
+
   test("an unrelated undeclared tool still fails closed through the bridged stream", async () => {
     const strayCall = {
       type: "function_call",