diff --git a/extensions/telegram/src/api-fetch.test.ts b/extensions/telegram/src/api-fetch.test.ts
index 4778d05cfe4..abaf4fe8b40 100644
--- a/extensions/telegram/src/api-fetch.test.ts
+++ b/extensions/telegram/src/api-fetch.test.ts
@@ -3,6 +3,35 @@ import { createRequire } from "node:module";
 import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import { fetchTelegramChatId } from "./api-fetch.js";
 
+const TELEGRAM_GETCHAT_JSON_CAP_BYTES = 4 * 1024 * 1024;
+
+function getChatOkResponse(id: number | string): Response {
+  return new Response(JSON.stringify({ ok: true, result: { id } }), {
+    status: 200,
+    headers: { "Content-Type": "application/json" },
+  });
+}
+
+function oversizedTelegramGetChatJsonResponse(onCancel: () => void): Response {
+  const response = new Response(
+    new ReadableStream<Uint8Array>({
+      start(controller) {
+        controller.enqueue(new Uint8Array(TELEGRAM_GETCHAT_JSON_CAP_BYTES + 1));
+      },
+      cancel() {
+        onCancel();
+      },
+    }),
+    { headers: { "content-type": "application/json" }, status: 200 },
+  );
+  Object.defineProperty(response, "json", {
+    value: async () => {
+      throw new Error("unbounded json reader was used");
+    },
+  });
+  return response;
+}
+
 const require = createRequire(import.meta.url);
 const EnvHttpProxyAgent = require("undici/lib/dispatcher/env-http-proxy-agent.js") as {
   new (opts?: Record<string, unknown>): Record<PropertyKey, unknown>;
@@ -67,18 +96,12 @@ describe("fetchTelegramChatId", () => {
   const cases = [
     {
       name: "returns stringified id when Telegram getChat succeeds",
-      fetchImpl: vi.fn(async () => ({
-        ok: true,
-        json: async () => ({ ok: true, result: { id: 12345 } }),
-      })),
+      fetchImpl: vi.fn(async () => getChatOkResponse(12345)),
       expected: "12345",
     },
     {
       name: "returns null when response is not ok",
-      fetchImpl: vi.fn(async () => ({
-        ok: false,
-        json: async () => ({}),
-      })),
+      fetchImpl: vi.fn(async () => new Response("{}", { status: 404 })),
       expected: null,
     },
     {
@@ -104,10 +127,7 @@ describe("fetchTelegramChatId", () => {
   }
 
   it("calls Telegram getChat endpoint", async () => {
-    const fetchMock = vi.fn(async () => ({
-      ok: true,
-      json: async () => ({ ok: true, result: { id: 12345 } }),
-    }));
+    const fetchMock = vi.fn(async () => getChatOkResponse(12345));
     vi.stubGlobal("fetch", fetchMock);
 
     await fetchTelegramChatId({ token: "abc", chatId: "@user" });
@@ -118,10 +138,7 @@ describe("fetchTelegramChatId", () => {
   });
 
   it("uses caller-provided fetch impl when present", async () => {
-    const customFetch = vi.fn(async () => ({
-      ok: true,
-      json: async () => ({ ok: true, result: { id: 12345 } }),
-    }));
+    const customFetch = vi.fn(async () => getChatOkResponse(12345));
     vi.stubGlobal(
       "fetch",
       vi.fn(async () => {
@@ -140,6 +157,24 @@ describe("fetchTelegramChatId", () => {
       undefined,
     );
   });
+
+  it("returns null for oversized getChat JSON responses and cancels the stream", async () => {
+    let cancelCount = 0;
+    const fetchImpl = vi.fn(async () =>
+      oversizedTelegramGetChatJsonResponse(() => {
+        cancelCount += 1;
+      }),
+    );
+
+    await expect(
+      fetchTelegramChatId({
+        token: "abc",
+        chatId: "@user",
+        fetchImpl: fetchImpl as unknown as typeof fetch,
+      }),
+    ).resolves.toBeNull();
+    expect(cancelCount).toBe(1);
+  });
 });
 
 describe("undici env proxy semantics", () => {
diff --git a/extensions/telegram/src/api-fetch.ts b/extensions/telegram/src/api-fetch.ts
index f5233aaf48a..4958392bfa9 100644
--- a/extensions/telegram/src/api-fetch.ts
+++ b/extensions/telegram/src/api-fetch.ts
@@ -1,8 +1,16 @@
 // Telegram plugin module implements api fetch behavior.
 import type { TelegramNetworkConfig } from "openclaw/plugin-sdk/config-contracts";
+import { readResponseWithLimit } from "openclaw/plugin-sdk/response-limit-runtime";
 import { resolveTelegramApiBase, resolveTelegramFetch } from "./fetch.js";
 import { makeProxyFetch } from "./proxy.js";
 
+const TELEGRAM_BOT_API_MAX_RESPONSE_BYTES = 4 * 1024 * 1024;
+
+type TelegramGetChatResponse = {
+  ok?: boolean;
+  result?: { id?: number | string };
+};
+
 export function resolveTelegramChatLookupFetch(params?: {
   proxyUrl?: string;
   network?: TelegramNetworkConfig;
@@ -47,10 +55,14 @@ export async function fetchTelegramChatId(params: {
     if (!res.ok) {
       return null;
     }
-    const data = (await res.json().catch(() => null)) as {
-      ok?: boolean;
-      result?: { id?: number | string };
-    } | null;
+    let data: TelegramGetChatResponse | null = null;
+    try {
+      data = JSON.parse(
+        (await readResponseWithLimit(res, TELEGRAM_BOT_API_MAX_RESPONSE_BYTES)).toString("utf8"),
+      ) as TelegramGetChatResponse;
+    } catch {
+      return null;
+    }
     const id = data?.ok ? data?.result?.id : undefined;
     if (typeof id === "number" || typeof id === "string") {
       return String(id);
diff --git a/scripts/proof-telegram-getchat-bound.mjs b/scripts/proof-telegram-getchat-bound.mjs
new file mode 100644
index 00000000000..516f1b840a2
--- /dev/null
+++ b/scripts/proof-telegram-getchat-bound.mjs
@@ -0,0 +1,159 @@
+import { once } from "node:events";
+// Loopback proof: fetchTelegramChatId (getChat) through the production Bot API read path.
+import { createServer } from "node:http";
+import { dirname, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const pkgRoot = resolve(dirname(fileURLToPath(import.meta.url)), "..");
+const TELEGRAM_BOT_API_MAX_RESPONSE_BYTES = 4 * 1024 * 1024;
+
+const { fetchTelegramChatId } = await import(`${pkgRoot}/extensions/telegram/src/api-fetch.ts`);
+
+const CAP = TELEGRAM_BOT_API_MAX_RESPONSE_BYTES;
+const STREAM_SIZE = 24 * 1024 * 1024;
+
+let allPassed = true;
+function check(label, val) {
+  console.log(`  ${val ? "ok" : "FAIL"}: ${label}`);
+  if (!val) {
+    allPassed = false;
+  }
+}
+
+let serverBytesWritten = 0;
+
+function createStreamingServer() {
+  return createServer((req, res) => {
+    if (req.url === "/huge") {
+      res.writeHead(200, { "Content-Type": "application/json" });
+      const chunk = Buffer.alloc(65536, 120);
+      const header = Buffer.from('{"ok":true,"result":{"id":1');
+      res.write(header);
+      serverBytesWritten += header.length;
+      let sent = header.length;
+      const writeNext = () => {
+        if (sent >= STREAM_SIZE) {
+          const tail = Buffer.from("}}");
+          res.write(tail);
+          serverBytesWritten += tail.length;
+          res.end();
+          return;
+        }
+        const ok = res.write(chunk);
+        serverBytesWritten += chunk.length;
+        sent += chunk.length;
+        if (ok) {
+          setImmediate(writeNext);
+        } else {
+          res.once("drain", writeNext);
+        }
+      };
+      writeNext();
+      return;
+    }
+    if (req.url?.includes("/getChat")) {
+      const chatId = new URL(req.url, "http://127.0.0.1").searchParams.get("chat_id");
+      if (chatId === "OVERSIZED") {
+        res.writeHead(200, { "Content-Type": "application/json" });
+        const chunk = Buffer.alloc(65536, 120);
+        const header = Buffer.from('{"ok":true,"result":{"id":1');
+        res.write(header);
+        serverBytesWritten += header.length;
+        let sent = header.length;
+        const writeNext = () => {
+          if (sent >= STREAM_SIZE) {
+            const tail = Buffer.from("}}");
+            res.write(tail);
+            serverBytesWritten += tail.length;
+            res.end();
+            return;
+          }
+          const ok = res.write(chunk);
+          serverBytesWritten += chunk.length;
+          sent += chunk.length;
+          if (ok) {
+            setImmediate(writeNext);
+          } else {
+            res.once("drain", writeNext);
+          }
+        };
+        writeNext();
+        return;
+      }
+      const body = JSON.stringify({ ok: true, result: { id: 123456789 } });
+      res.writeHead(200, {
+        "Content-Type": "application/json",
+        "Content-Length": String(Buffer.byteLength(body)),
+      });
+      res.end(body);
+      serverBytesWritten += Buffer.byteLength(body);
+      return;
+    }
+    res.writeHead(404);
+    res.end();
+  });
+}
+
+async function withServer(fn) {
+  serverBytesWritten = 0;
+  const server = createStreamingServer();
+  server.listen(0, "127.0.0.1");
+  await once(server, "listening");
+  const { port } = server.address();
+  try {
+    await fn(port);
+  } finally {
+    await new Promise((resolveDone) => {
+      server.close(resolveDone);
+    });
+  }
+}
+
+console.log(`\n[proof] fetchTelegramChatId (getChat) production path`);
+console.log(`  cap=${CAP} bytes (4 MiB), would-stream≈${STREAM_SIZE} bytes (24 MiB)\n`);
+
+await withServer(async (port) => {
+  serverBytesWritten = 0;
+  const chatId = await fetchTelegramChatId({
+    token: "proof-token",
+    chatId: "OVERSIZED",
+    apiRoot: `http://127.0.0.1:${port}`,
+  });
+  await new Promise((r) => {
+    setTimeout(r, 50);
+  });
+  check(
+    "oversized getChat fails closed with null (production fetchTelegramChatId)",
+    chatId === null,
+  );
+  check(
+    `server wrote ${serverBytesWritten} bytes, stopped before full 24 MiB stream`,
+    serverBytesWritten < STREAM_SIZE && serverBytesWritten > CAP,
+  );
+});
+
+await withServer(async (port) => {
+  serverBytesWritten = 0;
+  const res = await fetch(`http://127.0.0.1:${port}/huge`);
+  await res.json().catch(() => undefined);
+  await new Promise((r) => {
+    setTimeout(r, 50);
+  });
+  check(
+    `negative control: unbounded .json() wrote ${serverBytesWritten} bytes (>> ${CAP})`,
+    serverBytesWritten > CAP,
+  );
+});
+
+await withServer(async (port) => {
+  serverBytesWritten = 0;
+  const chatId = await fetchTelegramChatId({
+    token: "proof-token",
+    chatId: "-100123",
+    apiRoot: `http://127.0.0.1:${port}`,
+  });
+  check(`small getChat parsed through production path (id=${chatId})`, chatId === "123456789");
+});
+
+console.log(allPassed ? "\nALL PROOF ASSERTIONS PASSED" : "\nSOME ASSERTIONS FAILED");
+process.exit(allPassed ? 0 : 1);