diff --git a/src/server/index.ts b/src/server/index.ts
index b51156abe7..c8c67bd6ff 100644
--- a/src/server/index.ts
+++ b/src/server/index.ts
@@ -1752,6 +1752,11 @@ export function startServer(port?: number, deps: StartServerDeps = {}): Server<W
         if (!isAllowedRequestOrigin(req, policy)) {
           return withCors(formatErrorResponse(403, "origin_rejected", "cross-origin data-plane request blocked"), req, policy);
         }
+        // Compaction buffers the whole upstream turn before the first byte reaches the
+        // client, so the server-level `idleTimeout` (255 s) would close this connection
+        // under a long remote compact even though the upstream is still working. Opt out
+        // the same way the other buffered data-plane routes above and below do.
+        disableResponsesRequestTimeout(req, requestServer);
         const start = Date.now();
         const requestId = nextRequestLogId(start);
         const logCtx: RequestLogContext = {
diff --git a/tests/server/server-auth.test.ts b/tests/server/server-auth.test.ts
index 11fddb9772..deca8956be 100644
--- a/tests/server/server-auth.test.ts
+++ b/tests/server/server-auth.test.ts
@@ -602,6 +602,19 @@ describe("server local API auth", () => {
     })).toBe(false);
   });
 
+  test("compact route opts out of the request timeout before it buffers the compaction", () => {
+    // `/v1/responses/compact` answers only after the whole upstream turn has been collected,
+    // so unlike the streaming route it never sends a byte that would keep the connection
+    // alive. Without this opt-out the server-level `idleTimeout` closes a long remote
+    // compact mid-flight and the client sees a truncated body, not an error.
+    const source = readFileSync(new URL("../../src/server/index.ts", import.meta.url), "utf8");
+    const compactStart = source.indexOf('url.pathname === "/v1/responses/compact" && req.method === "POST"');
+    expect(compactStart).toBeGreaterThan(-1);
+    const handlerCall = source.indexOf("await handleResponsesCompact(req, config, logCtx", compactStart);
+    expect(handlerCall).toBeGreaterThan(compactStart);
+    expect(source.slice(compactStart, handlerCall)).toContain("disableResponsesRequestTimeout(req, requestServer);");
+  });
+
   test("responses handler keeps the request timeout until the body is fully accepted", async () => {
     let controller!: ReadableStreamDefaultController<Uint8Array>;
     const body = new ReadableStream<Uint8Array>({