diff --git a/README.md b/README.md
index df50a62..543ee3a 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ your app ──► /v1/chat/completions ──► cursor2api ──► api2.curs
 | Multi-turn agent loops (tool results replayed) | ✅ |
 | **Caller controls the tool set** — Cursor's native tools hidden | ✅ |
 | 200+ models, fetched live from your account | ✅ |
-| Multi-account pool, round-robin + cooldown | ✅ |
+| Multi-account pool, round-robin | ✅ |
 | Automatic token refresh | ✅ |
 | Client-supplied `system` prompt | ⚠️ best effort — [see below](#limitations) |
 
@@ -89,8 +89,9 @@ if the box needs one to reach `cursor.com`.
 desktop install (`state.vscdb`). Handy on your own laptop.
 
 Both write mode-0600 files and print only metadata, never the tokens. For several
-accounts, run either with `--merge --label some-name`; the pool round-robins over them
-and cools an account down for 60s after a failure.
+accounts, run either with `--merge --label some-name`; the pool round-robins over
+them. (There is a cooldown path in the pool, but nothing calls it yet — a failing
+account is retried on its next turn rather than being parked.)
 
 Access tokens last about two months and are refreshed automatically via the refresh
 token, so a one-time login is normally all you need.
@@ -126,6 +127,11 @@ resp = client.chat.completions.create(
 resp.choices[0].message.tool_calls[0].function.arguments   # '{"city":"Osaka"}'
 ```
 
+Errors carry a real status code rather than a blanket `502`: the upstream Connect code
+is mapped to what an OpenAI client expects, so subscription quota exhaustion arrives as
+`429` / `rate_limit_exceeded` and aggregators back off and retry instead of writing the
+gateway off as dead. Anything else upstream stays a `502`.
+
 Anything that speaks OpenAI works: Cline, Roo, Continue, LobeChat, one-api, your own
 scripts. If you aggregate several subscription providers behind
 [CLIProxyAPI](https://github.com/router-for-me/CLIProxyAPI), see
diff --git a/README.zh-CN.md b/README.zh-CN.md
index 079e83b..279d8a3 100644
--- a/README.zh-CN.md
+++ b/README.zh-CN.md
@@ -27,7 +27,7 @@
 | 多轮 agent loop（工具结果回放） | ✅ |
 | **工具集由调用方控制** —— Cursor 自带工具全部隐藏 | ✅ |
 | 200+ 模型，按账号实时拉取 | ✅ |
-| 多账号池，轮询 + 失败冷却 | ✅ |
+| 多账号池，轮询 | ✅ |
 | token 自动刷新 | ✅ |
 | 客户端 `system` 提示词 | ⚠️ 尽力而为，[见下](#已知限制) |
 
@@ -86,7 +86,8 @@ node dist/index.cjs
 `cursorAuth/accessToken`）。自己电脑上更省事。
 
 两个脚本都写 0600 权限的文件，只打印元信息，不打印 token。多账号就带
-`--merge --label 名字` 各跑一次；池子会轮询，某个账号失败后冷却 60 秒。
+`--merge --label 名字` 各跑一次；池子会轮询。（池子里有冷却逻辑，但目前没有调用方——
+失败的账号不会被摘掉，下一轮照常轮到它。）
 
 access token 有效期约两个月，到期前会用 refresh token 自动续，所以正常只需登录一次。
 
@@ -121,6 +122,10 @@ resp = client.chat.completions.create(
 resp.choices[0].message.tool_calls[0].function.arguments   # '{"city":"Osaka"}'
 ```
 
+错误会带真实状态码，不再一律 502：上游 Connect code 会映射成 OpenAI 客户端预期的状态，
+订阅配额耗尽返回 `429` / `rate_limit_exceeded`，聚合层因此会退避重试，而不是把网关当成
+挂了。其余上游故障仍然是 `502`。
+
 任何吃 OpenAI 格式的东西都能接：Cline、Roo、Continue、LobeChat、one-api，或者你自己的
 脚本。如果你用 [CLIProxyAPI](https://github.com/router-for-me/CLIProxyAPI) 聚合多个
 订阅型 provider，见 [docs/deploy-behind-cliproxyapi.md](docs/deploy-behind-cliproxyapi.md)。
diff --git a/src/cursor/session.ts b/src/cursor/session.ts
index c7a9abf..a812fc3 100644
--- a/src/cursor/session.ts
+++ b/src/cursor/session.ts
@@ -37,7 +37,7 @@ export type TurnEvent =
   | { type: "thinking"; delta: string }
   | { type: "tool_call"; id: string; name: string; args: Record<string, unknown> }
   | { type: "usage"; inputTokens?: number; outputTokens?: number }
-  | { type: "done"; reason: "stop" | "tool_calls" | "error"; error?: string };
+  | { type: "done"; reason: "stop" | "tool_calls" | "error"; error?: string; code?: string };
 
 export interface RunTurnOptions {
   token: string;
@@ -51,6 +51,26 @@ export interface RunTurnOptions {
   signal?: AbortSignal;
 }
 
+/**
+ * Upstream tool-call ids are not always safe to hand back to a caller: grok models
+ * return two ids joined by a literal newline (`call-<uuid>-0\nfc_<uuid>_0`). The
+ * caller round-trips this string as `tool_call_id`, and anything that re-encodes it
+ * under a stricter schema — Anthropic's `tool_use_id` pattern, for one — rejects the
+ * raw form, so fold everything outside the id alphabet into `_`.
+ */
+function safeToolCallId(raw: unknown): string {
+  const id = String(raw ?? "").replace(/[^A-Za-z0-9_-]/g, "_");
+  return id || `call_${randomUUID()}`;
+}
+
+/** Map an upstream HTTP status onto the Connect code the trailer would have carried. */
+function connectCodeForHttp(status: number): string | undefined {
+  if (status === 429) return "resource_exhausted";
+  if (status === 401) return "unauthenticated";
+  if (status === 403) return "permission_denied";
+  return undefined;
+}
+
 const FLAG_COMPRESSED = 0x01;
 const FLAG_END_STREAM = 0x02;
 
@@ -154,7 +174,14 @@ export async function* runTurn(opts: RunTurnOptions): AsyncGenerator<TurnEvent>
 
   req.on("response", (h) => {
     const status = Number(h[":status"] || 0);
-    if (status !== 200) end({ type: "done", reason: "error", error: `upstream HTTP ${status}` });
+    if (status !== 200) {
+      end({
+        type: "done",
+        reason: "error",
+        code: connectCodeForHttp(status),
+        error: `upstream HTTP ${status}`,
+      });
+    }
   });
 
   let buffer = Buffer.alloc(0);
@@ -195,6 +222,7 @@ export async function* runTurn(opts: RunTurnOptions): AsyncGenerator<TurnEvent>
         return {
           type: "done",
           reason: "error",
+          code: parsed.error.code,
           error: `${parsed.error.code ?? "error"}: ${parsed.error.message ?? trailer}`,
         };
       }
@@ -256,7 +284,7 @@ export async function* runTurn(opts: RunTurnOptions): AsyncGenerator<TurnEvent>
         for (const [key, raw] of Object.entries(a.args ?? {})) args[key] = decodeArgValue(raw);
         push({
           type: "tool_call",
-          id: String(a.toolCallId ?? randomUUID()),
+          id: safeToolCallId(a.toolCallId),
           name: String(a.name ?? a.toolName ?? "unknown"),
           args,
         });
@@ -283,7 +311,7 @@ export async function* runTurn(opts: RunTurnOptions): AsyncGenerator<TurnEvent>
   req.on("end", () => end({ type: "done", reason: "stop" }));
 
   const timer = setTimeout(
-    () => end({ type: "done", reason: "error", error: "upstream timeout" }),
+    () => end({ type: "done", reason: "error", code: "deadline_exceeded", error: "upstream timeout" }),
     config.requestTimeoutMs,
   );
   const onAbort = (): void => end({ type: "done", reason: "error", error: "client aborted" });
diff --git a/src/server.ts b/src/server.ts
index 0e0fd39..a309787 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -121,6 +121,7 @@ interface Collected {
   usage: { inputTokens?: number; outputTokens?: number };
   reason: "stop" | "tool_calls" | "error";
   error?: string;
+  code?: string;
 }
 
 async function collect(events: AsyncGenerator<TurnEvent>): Promise<Collected> {
@@ -135,6 +136,7 @@ async function collect(events: AsyncGenerator<TurnEvent>): Promise<Collected> {
     } else if (ev.type === "done") {
       out.reason = ev.reason;
       out.error = ev.error;
+      out.code = ev.code;
     }
   }
   return out;
@@ -150,7 +152,8 @@ async function bufferResponse(
   const result = await collect(events);
   if (result.reason === "error") {
     deps.log(`upstream error (${accountLabel}): ${result.error}`);
-    sendJson(res, 502, { error: { message: result.error ?? "upstream error", type: "upstream_error" } });
+    const { status, body } = upstreamError(result.code, result.error);
+    sendJson(res, status, body);
     return;
   }
   const id = `chatcmpl-${randomUUID()}`;
@@ -241,12 +244,13 @@ async function streamResponse(
     } else if (ev.type === "done") {
       if (ev.reason === "error") {
         deps.log(`upstream error (${accountLabel}): ${ev.error}`);
+        const { status, body } = upstreamError(ev.code, ev.error);
         if (!opened) {
-          sendJson(res, 502, { error: { message: ev.error ?? "upstream error", type: "upstream_error" } });
+          sendJson(res, status, body);
           return;
         }
         // Mid-stream failures can only be reported inside the stream.
-        emit(res, { error: { message: ev.error ?? "upstream error", type: "upstream_error" } });
+        emit(res, body);
         res.write("data: [DONE]\n\n");
         res.end();
         return;
@@ -284,6 +288,36 @@ function chunk(
   };
 }
 
+/**
+ * Connect codes that a caller can act on differently, mapped to the HTTP status an
+ * OpenAI client expects. Quota exhaustion is the one that matters in practice: as a
+ * 502 it reads as a broken gateway, so clients and aggregators give up instead of
+ * backing off and retrying. Anything unrecognised stays a 502 rather than being
+ * dressed up as a client error.
+ */
+const STATUS_BY_CODE: Record<string, number> = {
+  resource_exhausted: 429,
+  unauthenticated: 401,
+  permission_denied: 403,
+  invalid_argument: 400,
+  not_found: 404,
+  unimplemented: 501,
+  unavailable: 503,
+  deadline_exceeded: 504,
+};
+
+function upstreamError(
+  code: string | undefined,
+  message: string | undefined,
+): { status: number; body: { error: { message: string; type: string; code?: string } } } {
+  const status = (code ? STATUS_BY_CODE[code] : undefined) ?? 502;
+  const type = status === 429 ? "rate_limit_exceeded" : "upstream_error";
+  return {
+    status,
+    body: { error: { message: message ?? "upstream error", type, ...(code ? { code } : {}) } },
+  };
+}
+
 function usageBlock(usage: Collected["usage"]): Record<string, number> {
   const prompt = usage.inputTokens ?? 0;
   const completion = usage.outputTokens ?? 0;