diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c605803a44..149a517fd64 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Telegram/Webhook: pre-initialize webhook bots, switch webhook processing to callback-mode JSON handling, and preserve full near-limit payload reads under delayed handlers to prevent webhook request hangs and dropped updates. (#26156)
 - Agents/Subagents delivery: refactor subagent completion announce dispatch into an explicit queue/direct/fallback state machine, recover outbound channel-plugin resolution in cold/stale plugin-registry states across announce/message/gateway send paths, finalize cleanup bookkeeping when announce flow rejects, and treat Telegram sends without `message_id` as delivery failures (instead of false-success `"unknown"` IDs). (#26867, #25961, #26803, #25069, #26741) Thanks @SmithLabsLLC and @docaohieu2808.
 - Security/SSRF guard: classify IPv6 multicast literals (`ff00::/8`) as blocked/private-internal targets in shared SSRF IP checks, preventing multicast literals from bypassing URL-host preflight and DNS answer validation. This ships in the next npm release (`2026.2.25`). Thanks @zpbrent for reporting.
 - Slack/Session threads: prevent oversized parent-session inheritance from silently bricking new thread sessions, surface embedded context-overflow empty-result failures to users, and add configurable `session.parentForkMaxTokens` (default `100000`, `0` disables). (#26912) Thanks @markshields-tl.
diff --git a/src/telegram/webhook.test.ts b/src/telegram/webhook.test.ts
index 2c943a4be6f..0117c55823a 100644
--- a/src/telegram/webhook.test.ts
+++ b/src/telegram/webhook.test.ts
@@ -1,24 +1,26 @@
+import { createHash } from "node:crypto";
+import { once } from "node:events";
+import { request } from "node:http";
+import { setTimeout as sleep } from "node:timers/promises";
 import { describe, expect, it, vi } from "vitest";
 import { startTelegramWebhook } from "./webhook.js";
 
-const handlerSpy = vi.hoisted(() =>
-  vi.fn(
-    (_req: unknown, res: { writeHead: (status: number) => void; end: (body?: string) => void }) => {
-      res.writeHead(200);
-      res.end("ok");
-    },
-  ),
-);
+const handlerSpy = vi.hoisted(() => vi.fn((..._args: unknown[]): unknown => undefined));
 const setWebhookSpy = vi.hoisted(() => vi.fn());
+const deleteWebhookSpy = vi.hoisted(() => vi.fn(async () => true));
+const initSpy = vi.hoisted(() => vi.fn(async () => undefined));
 const stopSpy = vi.hoisted(() => vi.fn());
 const webhookCallbackSpy = vi.hoisted(() => vi.fn(() => handlerSpy));
 const createTelegramBotSpy = vi.hoisted(() =>
   vi.fn(() => ({
-    api: { setWebhook: setWebhookSpy },
+    init: initSpy,
+    api: { setWebhook: setWebhookSpy, deleteWebhook: deleteWebhookSpy },
     stop: stopSpy,
   })),
 );
 
+const WEBHOOK_POST_TIMEOUT_MS = process.platform === "win32" ? 20_000 : 8_000;
+
 vi.mock("grammy", async (importOriginal) => {
   const actual = await importOriginal<typeof import("grammy")>();
   return {
@@ -31,8 +33,178 @@ vi.mock("./bot.js", () => ({
   createTelegramBot: createTelegramBotSpy,
 }));
 
+async function fetchWithTimeout(
+  input: string,
+  init: Omit<RequestInit, "signal">,
+  timeoutMs: number,
+): Promise<Response> {
+  const abort = new AbortController();
+  const timer = setTimeout(() => {
+    abort.abort();
+  }, timeoutMs);
+  try {
+    return await fetch(input, { ...init, signal: abort.signal });
+  } finally {
+    clearTimeout(timer);
+  }
+}
+
+async function postWebhookJson(params: {
+  url: string;
+  payload: string;
+  secret?: string;
+  timeoutMs?: number;
+}): Promise<Response> {
+  return await fetchWithTimeout(
+    params.url,
+    {
+      method: "POST",
+      headers: {
+        "content-type": "application/json",
+        ...(params.secret ? { "x-telegram-bot-api-secret-token": params.secret } : {}),
+      },
+      body: params.payload,
+    },
+    params.timeoutMs ?? 5_000,
+  );
+}
+
+function createDeterministicRng(seed: number): () => number {
+  let state = seed >>> 0;
+  return () => {
+    state = (state * 1_664_525 + 1_013_904_223) >>> 0;
+    return state / 4_294_967_296;
+  };
+}
+
+async function postWebhookPayloadWithChunkPlan(params: {
+  port: number;
+  path: string;
+  payload: string;
+  secret: string;
+  mode: "single" | "random-chunked";
+  timeoutMs?: number;
+}): Promise<{ statusCode: number; body: string }> {
+  const payloadBuffer = Buffer.from(params.payload, "utf-8");
+  return await new Promise((resolve, reject) => {
+    let bytesQueued = 0;
+    let chunksQueued = 0;
+    let phase: "writing" | "awaiting-response" = "writing";
+    let settled = false;
+    const finishResolve = (value: { statusCode: number; body: string }) => {
+      if (settled) {
+        return;
+      }
+      settled = true;
+      clearTimeout(timeout);
+      resolve(value);
+    };
+    const finishReject = (error: unknown) => {
+      if (settled) {
+        return;
+      }
+      settled = true;
+      clearTimeout(timeout);
+      reject(error);
+    };
+
+    const req = request(
+      {
+        hostname: "127.0.0.1",
+        port: params.port,
+        path: params.path,
+        method: "POST",
+        headers: {
+          "content-type": "application/json",
+          "content-length": String(payloadBuffer.length),
+          "x-telegram-bot-api-secret-token": params.secret,
+        },
+      },
+      (res) => {
+        const chunks: Buffer[] = [];
+        res.on("data", (chunk: Buffer | string) => {
+          chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
+        });
+        res.on("end", () => {
+          finishResolve({
+            statusCode: res.statusCode ?? 0,
+            body: Buffer.concat(chunks).toString("utf-8"),
+          });
+        });
+      },
+    );
+
+    const timeout = setTimeout(() => {
+      finishReject(
+        new Error(
+          `webhook post timed out after ${params.timeoutMs ?? 15_000}ms (phase=${phase}, bytesQueued=${bytesQueued}, chunksQueued=${chunksQueued}, totalBytes=${payloadBuffer.length})`,
+        ),
+      );
+      req.destroy();
+    }, params.timeoutMs ?? 15_000);
+
+    req.on("error", (error) => {
+      finishReject(error);
+    });
+
+    const writeAll = async () => {
+      if (params.mode === "single") {
+        req.end(payloadBuffer);
+        return;
+      }
+
+      const rng = createDeterministicRng(26156);
+      let offset = 0;
+      while (offset < payloadBuffer.length) {
+        const remaining = payloadBuffer.length - offset;
+        const nextSize = Math.max(1, Math.min(remaining, 1 + Math.floor(rng() * 8_192)));
+        const chunk = payloadBuffer.subarray(offset, offset + nextSize);
+        const canContinue = req.write(chunk);
+        offset += nextSize;
+        bytesQueued = offset;
+        chunksQueued += 1;
+        if (chunksQueued % 10 === 0) {
+          await sleep(1 + Math.floor(rng() * 3));
+        }
+        if (!canContinue) {
+          // Windows CI occasionally stalls on waiting for drain indefinitely.
+          // Bound the wait, then continue queuing this small (~1MB) payload.
+          await Promise.race([once(req, "drain"), sleep(25)]);
+        }
+      }
+      phase = "awaiting-response";
+      req.end();
+    };
+
+    void writeAll().catch((error) => {
+      finishReject(error);
+    });
+  });
+}
+
+function createNearLimitTelegramPayload(): { payload: string; sizeBytes: number } {
+  const maxBytes = 1_024 * 1_024;
+  const targetBytes = maxBytes - 4_096;
+  const shell = { update_id: 77_777, message: { text: "" } };
+  const shellSize = Buffer.byteLength(JSON.stringify(shell), "utf-8");
+  const textLength = Math.max(1, targetBytes - shellSize);
+  const pattern = "the quick brown fox jumps over the lazy dog ";
+  const repeats = Math.ceil(textLength / pattern.length);
+  const text = pattern.repeat(repeats).slice(0, textLength);
+  const payload = JSON.stringify({
+    update_id: 77_777,
+    message: { text },
+  });
+  return { payload, sizeBytes: Buffer.byteLength(payload, "utf-8") };
+}
+
+function sha256(text: string): string {
+  return createHash("sha256").update(text).digest("hex");
+}
+
 describe("startTelegramWebhook", () => {
   it("starts server, registers webhook, and serves health", async () => {
+    initSpy.mockClear();
     createTelegramBotSpy.mockClear();
     webhookCallbackSpy.mockClear();
     const abort = new AbortController();
@@ -59,6 +231,7 @@ describe("startTelegramWebhook", () => {
 
     const health = await fetch(`${url}/healthz`);
     expect(health.status).toBe(200);
+    expect(initSpy).toHaveBeenCalledTimes(1);
     expect(setWebhookSpy).toHaveBeenCalled();
     expect(webhookCallbackSpy).toHaveBeenCalledWith(
       expect.objectContaining({
@@ -66,7 +239,7 @@ describe("startTelegramWebhook", () => {
           setWebhook: expect.any(Function),
         }),
       }),
-      "http",
+      "callback",
       {
         secretToken: "secret",
         onTimeout: "return",
@@ -101,7 +274,13 @@ describe("startTelegramWebhook", () => {
     if (!addr || typeof addr === "string") {
       throw new Error("no addr");
     }
-    await fetch(`http://127.0.0.1:${addr.port}/hook`, { method: "POST" });
+    const payload = JSON.stringify({ update_id: 1, message: { text: "hello" } });
+    const response = await postWebhookJson({
+      url: `http://127.0.0.1:${addr.port}/hook`,
+      payload,
+      secret: "secret",
+    });
+    expect(response.status).toBe(200);
     expect(handlerSpy).toHaveBeenCalled();
     abort.abort();
   });
@@ -113,4 +292,371 @@ describe("startTelegramWebhook", () => {
       }),
     ).rejects.toThrow(/requires a non-empty secret token/i);
   });
+
+  it("registers webhook using the bound listening port when port is 0", async () => {
+    setWebhookSpy.mockClear();
+    const abort = new AbortController();
+    const { server } = await startTelegramWebhook({
+      token: "tok",
+      secret: "secret",
+      port: 0,
+      abortSignal: abort.signal,
+      path: "/hook",
+    });
+    try {
+      const addr = server.address();
+      if (!addr || typeof addr === "string") {
+        throw new Error("no addr");
+      }
+      expect(addr.port).toBeGreaterThan(0);
+      expect(setWebhookSpy).toHaveBeenCalledTimes(1);
+      expect(setWebhookSpy).toHaveBeenCalledWith(
+        `http://127.0.0.1:${addr.port}/hook`,
+        expect.objectContaining({
+          secret_token: "secret",
+        }),
+      );
+    } finally {
+      abort.abort();
+    }
+  });
+
+  it("keeps webhook payload readable when callback delays body read", async () => {
+    handlerSpy.mockImplementationOnce(async (...args: unknown[]) => {
+      const [update, reply] = args as [unknown, (json: string) => Promise<void>];
+      await sleep(50);
+      await reply(JSON.stringify(update));
+    });
+
+    const abort = new AbortController();
+    const { server } = await startTelegramWebhook({
+      token: "tok",
+      secret: "secret",
+      port: 0,
+      abortSignal: abort.signal,
+      path: "/hook",
+    });
+    try {
+      const addr = server.address();
+      if (!addr || typeof addr === "string") {
+        throw new Error("no addr");
+      }
+
+      const payload = JSON.stringify({ update_id: 1, message: { text: "hello" } });
+      const res = await postWebhookJson({
+        url: `http://127.0.0.1:${addr.port}/hook`,
+        payload,
+        secret: "secret",
+      });
+      expect(res.status).toBe(200);
+      const responseBody = await res.text();
+      expect(JSON.parse(responseBody)).toEqual(JSON.parse(payload));
+    } finally {
+      abort.abort();
+    }
+  });
+
+  it("keeps webhook payload readable across multiple delayed reads", async () => {
+    const seenPayloads: string[] = [];
+    const delayedHandler = async (...args: unknown[]) => {
+      const [update, reply] = args as [unknown, (json: string) => Promise<void>];
+      await sleep(50);
+      seenPayloads.push(JSON.stringify(update));
+      await reply("ok");
+    };
+    handlerSpy.mockImplementationOnce(delayedHandler).mockImplementationOnce(delayedHandler);
+
+    const abort = new AbortController();
+    const { server } = await startTelegramWebhook({
+      token: "tok",
+      secret: "secret",
+      port: 0,
+      abortSignal: abort.signal,
+      path: "/hook",
+    });
+    try {
+      const addr = server.address();
+      if (!addr || typeof addr === "string") {
+        throw new Error("no addr");
+      }
+
+      const payloads = [
+        JSON.stringify({ update_id: 1, message: { text: "first" } }),
+        JSON.stringify({ update_id: 2, message: { text: "second" } }),
+      ];
+
+      for (const payload of payloads) {
+        const res = await postWebhookJson({
+          url: `http://127.0.0.1:${addr.port}/hook`,
+          payload,
+          secret: "secret",
+        });
+        expect(res.status).toBe(200);
+      }
+
+      expect(seenPayloads.map((x) => JSON.parse(x))).toEqual(payloads.map((x) => JSON.parse(x)));
+    } finally {
+      abort.abort();
+    }
+  });
+
+  it("processes a second request after first-request delayed-init data loss", async () => {
+    const seenUpdates: unknown[] = [];
+    webhookCallbackSpy.mockImplementationOnce(
+      () =>
+        vi.fn(
+          (
+            update: unknown,
+            reply: (json: string) => Promise<void>,
+            _secretHeader: string | undefined,
+            _unauthorized: () => Promise<void>,
+          ) => {
+            seenUpdates.push(update);
+            void (async () => {
+              await sleep(50);
+              await reply("ok");
+            })();
+          },
+        ) as unknown as typeof handlerSpy,
+    );
+
+    const secret = "secret";
+    const abort = new AbortController();
+    const { server } = await startTelegramWebhook({
+      token: "tok",
+      secret,
+      port: 0,
+      abortSignal: abort.signal,
+      path: "/hook",
+    });
+
+    try {
+      const address = server.address();
+      if (!address || typeof address === "string") {
+        throw new Error("no addr");
+      }
+
+      const firstPayload = JSON.stringify({ update_id: 100, message: { text: "first" } });
+      const secondPayload = JSON.stringify({ update_id: 101, message: { text: "second" } });
+      const firstResponse = await postWebhookPayloadWithChunkPlan({
+        port: address.port,
+        path: "/hook",
+        payload: firstPayload,
+        secret,
+        mode: "single",
+        timeoutMs: WEBHOOK_POST_TIMEOUT_MS,
+      });
+      const secondResponse = await postWebhookPayloadWithChunkPlan({
+        port: address.port,
+        path: "/hook",
+        payload: secondPayload,
+        secret,
+        mode: "single",
+        timeoutMs: WEBHOOK_POST_TIMEOUT_MS,
+      });
+
+      expect(firstResponse.statusCode).toBe(200);
+      expect(secondResponse.statusCode).toBe(200);
+      expect(seenUpdates).toEqual([JSON.parse(firstPayload), JSON.parse(secondPayload)]);
+    } finally {
+      abort.abort();
+    }
+  });
+
+  it("handles near-limit payload with random chunk writes and event-loop yields", async () => {
+    const seenUpdates: Array<{ update_id: number; message: { text: string } }> = [];
+    webhookCallbackSpy.mockImplementationOnce(
+      () =>
+        vi.fn(
+          (
+            update: unknown,
+            reply: (json: string) => Promise<void>,
+            _secretHeader: string | undefined,
+            _unauthorized: () => Promise<void>,
+          ) => {
+            seenUpdates.push(update as { update_id: number; message: { text: string } });
+            void reply("ok");
+          },
+        ) as unknown as typeof handlerSpy,
+    );
+
+    const { payload, sizeBytes } = createNearLimitTelegramPayload();
+    expect(sizeBytes).toBeLessThan(1_024 * 1_024);
+    expect(sizeBytes).toBeGreaterThan(256 * 1_024);
+    const expected = JSON.parse(payload) as { update_id: number; message: { text: string } };
+
+    const secret = "secret";
+    const abort = new AbortController();
+    const { server } = await startTelegramWebhook({
+      token: "tok",
+      secret,
+      port: 0,
+      abortSignal: abort.signal,
+      path: "/hook",
+    });
+
+    try {
+      const address = server.address();
+      if (!address || typeof address === "string") {
+        throw new Error("no addr");
+      }
+
+      const response = await postWebhookPayloadWithChunkPlan({
+        port: address.port,
+        path: "/hook",
+        payload,
+        secret,
+        mode: "random-chunked",
+        timeoutMs: WEBHOOK_POST_TIMEOUT_MS,
+      });
+
+      expect(response.statusCode).toBe(200);
+      expect(seenUpdates).toHaveLength(1);
+      expect(seenUpdates[0]?.update_id).toBe(expected.update_id);
+      expect(seenUpdates[0]?.message.text.length).toBe(expected.message.text.length);
+      expect(sha256(seenUpdates[0]?.message.text ?? "")).toBe(sha256(expected.message.text));
+    } finally {
+      abort.abort();
+    }
+  });
+
+  it("handles near-limit payload written in a single request write", async () => {
+    const seenUpdates: Array<{ update_id: number; message: { text: string } }> = [];
+    webhookCallbackSpy.mockImplementationOnce(
+      () =>
+        vi.fn(
+          (
+            update: unknown,
+            reply: (json: string) => Promise<void>,
+            _secretHeader: string | undefined,
+            _unauthorized: () => Promise<void>,
+          ) => {
+            seenUpdates.push(update as { update_id: number; message: { text: string } });
+            void reply("ok");
+          },
+        ) as unknown as typeof handlerSpy,
+    );
+
+    const { payload, sizeBytes } = createNearLimitTelegramPayload();
+    expect(sizeBytes).toBeLessThan(1_024 * 1_024);
+    expect(sizeBytes).toBeGreaterThan(256 * 1_024);
+    const expected = JSON.parse(payload) as { update_id: number; message: { text: string } };
+
+    const secret = "secret";
+    const abort = new AbortController();
+    const { server } = await startTelegramWebhook({
+      token: "tok",
+      secret,
+      port: 0,
+      abortSignal: abort.signal,
+      path: "/hook",
+    });
+
+    try {
+      const address = server.address();
+      if (!address || typeof address === "string") {
+        throw new Error("no addr");
+      }
+
+      const response = await postWebhookPayloadWithChunkPlan({
+        port: address.port,
+        path: "/hook",
+        payload,
+        secret,
+        mode: "single",
+        timeoutMs: WEBHOOK_POST_TIMEOUT_MS,
+      });
+
+      expect(response.statusCode).toBe(200);
+      expect(seenUpdates).toHaveLength(1);
+      expect(seenUpdates[0]?.update_id).toBe(expected.update_id);
+      expect(seenUpdates[0]?.message.text.length).toBe(expected.message.text.length);
+      expect(sha256(seenUpdates[0]?.message.text ?? "")).toBe(sha256(expected.message.text));
+    } finally {
+      abort.abort();
+    }
+  });
+
+  it("rejects payloads larger than 1MB before invoking webhook handler", async () => {
+    handlerSpy.mockClear();
+    const abort = new AbortController();
+    const { server } = await startTelegramWebhook({
+      token: "tok",
+      secret: "secret",
+      port: 0,
+      abortSignal: abort.signal,
+      path: "/hook",
+    });
+
+    try {
+      const address = server.address();
+      if (!address || typeof address === "string") {
+        throw new Error("no addr");
+      }
+
+      const responseOrError = await new Promise<
+        | { kind: "response"; statusCode: number; body: string }
+        | { kind: "error"; code: string | undefined }
+      >((resolve) => {
+        const req = request(
+          {
+            hostname: "127.0.0.1",
+            port: address.port,
+            path: "/hook",
+            method: "POST",
+            headers: {
+              "content-type": "application/json",
+              "content-length": String(1_024 * 1_024 + 2_048),
+              "x-telegram-bot-api-secret-token": "secret",
+            },
+          },
+          (res) => {
+            const chunks: Buffer[] = [];
+            res.on("data", (chunk: Buffer | string) => {
+              chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
+            });
+            res.on("end", () => {
+              resolve({
+                kind: "response",
+                statusCode: res.statusCode ?? 0,
+                body: Buffer.concat(chunks).toString("utf-8"),
+              });
+            });
+          },
+        );
+        req.on("error", (error: NodeJS.ErrnoException) => {
+          resolve({ kind: "error", code: error.code });
+        });
+        req.end("{}");
+      });
+
+      if (responseOrError.kind === "response") {
+        expect(responseOrError.statusCode).toBe(413);
+        expect(responseOrError.body).toBe("Payload too large");
+      } else {
+        expect(responseOrError.code).toBeOneOf(["ECONNRESET", "EPIPE"]);
+      }
+      expect(handlerSpy).not.toHaveBeenCalled();
+    } finally {
+      abort.abort();
+    }
+  });
+
+  it("de-registers webhook when shutting down", async () => {
+    deleteWebhookSpy.mockClear();
+    const abort = new AbortController();
+    await startTelegramWebhook({
+      token: "tok",
+      secret: "secret",
+      port: 0,
+      abortSignal: abort.signal,
+      path: "/hook",
+    });
+
+    abort.abort();
+    await sleep(25);
+
+    expect(deleteWebhookSpy).toHaveBeenCalledTimes(1);
+    expect(deleteWebhookSpy).toHaveBeenCalledWith({ drop_pending_updates: false });
+  });
 });
diff --git a/src/telegram/webhook.ts b/src/telegram/webhook.ts
index 9eb3c73d7f4..0fd887f956c 100644
--- a/src/telegram/webhook.ts
+++ b/src/telegram/webhook.ts
@@ -3,7 +3,7 @@ import { webhookCallback } from "grammy";
 import type { OpenClawConfig } from "../config/config.js";
 import { isDiagnosticsEnabled } from "../infra/diagnostic-events.js";
 import { formatErrorMessage } from "../infra/errors.js";
-import { installRequestBodyLimitGuard } from "../infra/http-body.js";
+import { readJsonBodyWithLimit } from "../infra/http-body.js";
 import {
   logWebhookError,
   logWebhookProcessed,
@@ -21,6 +21,59 @@ const TELEGRAM_WEBHOOK_MAX_BODY_BYTES = 1024 * 1024;
 const TELEGRAM_WEBHOOK_BODY_TIMEOUT_MS = 30_000;
 const TELEGRAM_WEBHOOK_CALLBACK_TIMEOUT_MS = 10_000;
 
+async function listenHttpServer(params: {
+  server: ReturnType<typeof createServer>;
+  port: number;
+  host: string;
+}) {
+  await new Promise<void>((resolve, reject) => {
+    const onError = (err: Error) => {
+      params.server.off("error", onError);
+      reject(err);
+    };
+    params.server.once("error", onError);
+    params.server.listen(params.port, params.host, () => {
+      params.server.off("error", onError);
+      resolve();
+    });
+  });
+}
+
+function resolveWebhookPublicUrl(params: {
+  configuredPublicUrl?: string;
+  server: ReturnType<typeof createServer>;
+  path: string;
+  host: string;
+  port: number;
+}) {
+  if (params.configuredPublicUrl) {
+    return params.configuredPublicUrl;
+  }
+  const address = params.server.address();
+  if (address && typeof address !== "string") {
+    const resolvedHost =
+      params.host === "0.0.0.0" || address.address === "0.0.0.0" || address.address === "::"
+        ? "localhost"
+        : address.address;
+    return `http://${resolvedHost}:${address.port}${params.path}`;
+  }
+  const fallbackHost = params.host === "0.0.0.0" ? "localhost" : params.host;
+  return `http://${fallbackHost}:${params.port}${params.path}`;
+}
+
+async function initializeTelegramWebhookBot(params: {
+  bot: ReturnType<typeof createTelegramBot>;
+  runtime: RuntimeEnv;
+  abortSignal?: AbortSignal;
+}) {
+  const initSignal = params.abortSignal as Parameters<(typeof params.bot)["init"]>[0];
+  await withTelegramApiErrorLogging({
+    operation: "getMe",
+    runtime: params.runtime,
+    fn: () => params.bot.init(initSignal),
+  });
+}
+
 export async function startTelegramWebhook(opts: {
   token: string;
   accountId?: string;
@@ -55,7 +108,12 @@ export async function startTelegramWebhook(opts: {
     config: opts.config,
     accountId: opts.accountId,
   });
-  const handler = webhookCallback(bot, "http", {
+  await initializeTelegramWebhookBot({
+    bot,
+    runtime,
+    abortSignal: opts.abortSignal,
+  });
+  const handler = webhookCallback(bot, "callback", {
     secretToken: secret,
     onTimeout: "return",
     timeoutMilliseconds: TELEGRAM_WEBHOOK_CALLBACK_TIMEOUT_MS,
@@ -66,6 +124,14 @@ export async function startTelegramWebhook(opts: {
   }
 
   const server = createServer((req, res) => {
+    const respondText = (statusCode: number, text = "") => {
+      if (res.headersSent || res.writableEnded) {
+        return;
+      }
+      res.writeHead(statusCode, { "Content-Type": "text/plain; charset=utf-8" });
+      res.end(text);
+    };
+
     if (req.url === healthPath) {
       res.writeHead(200);
       res.end("ok");
@@ -80,69 +146,125 @@ export async function startTelegramWebhook(opts: {
     if (diagnosticsEnabled) {
       logWebhookReceived({ channel: "telegram", updateType: "telegram-post" });
     }
-    const guard = installRequestBodyLimitGuard(req, res, {
-      maxBytes: TELEGRAM_WEBHOOK_MAX_BODY_BYTES,
-      timeoutMs: TELEGRAM_WEBHOOK_BODY_TIMEOUT_MS,
-      responseFormat: "text",
-    });
-    if (guard.isTripped()) {
-      return;
-    }
-    const handled = handler(req, res);
-    if (handled && typeof handled.catch === "function") {
-      void handled
-        .then(() => {
-          if (diagnosticsEnabled) {
-            logWebhookProcessed({
-              channel: "telegram",
-              updateType: "telegram-post",
-              durationMs: Date.now() - startTime,
-            });
-          }
-        })
-        .catch((err) => {
-          if (guard.isTripped()) {
-            return;
-          }
-          const errMsg = formatErrorMessage(err);
-          if (diagnosticsEnabled) {
-            logWebhookError({
-              channel: "telegram",
-              updateType: "telegram-post",
-              error: errMsg,
-            });
-          }
-          runtime.log?.(`webhook handler failed: ${errMsg}`);
-          if (!res.headersSent) {
-            res.writeHead(500);
-          }
-          res.end();
-        })
-        .finally(() => {
-          guard.dispose();
+    void (async () => {
+      const body = await readJsonBodyWithLimit(req, {
+        maxBytes: TELEGRAM_WEBHOOK_MAX_BODY_BYTES,
+        timeoutMs: TELEGRAM_WEBHOOK_BODY_TIMEOUT_MS,
+        emptyObjectOnEmpty: false,
+      });
+      if (!body.ok) {
+        if (body.code === "PAYLOAD_TOO_LARGE") {
+          respondText(413, body.error);
+          return;
+        }
+        if (body.code === "REQUEST_BODY_TIMEOUT") {
+          respondText(408, body.error);
+          return;
+        }
+        if (body.code === "CONNECTION_CLOSED") {
+          respondText(400, body.error);
+          return;
+        }
+        respondText(400, body.error);
+        return;
+      }
+
+      let replied = false;
+      const reply = async (json: string) => {
+        if (replied) {
+          return;
+        }
+        replied = true;
+        if (res.headersSent || res.writableEnded) {
+          return;
+        }
+        res.writeHead(200, { "Content-Type": "application/json; charset=utf-8" });
+        res.end(json);
+      };
+      const unauthorized = async () => {
+        if (replied) {
+          return;
+        }
+        replied = true;
+        respondText(401, "unauthorized");
+      };
+      const secretHeaderRaw = req.headers["x-telegram-bot-api-secret-token"];
+      const secretHeader = Array.isArray(secretHeaderRaw) ? secretHeaderRaw[0] : secretHeaderRaw;
+
+      await handler(body.value, reply, secretHeader, unauthorized);
+      if (!replied) {
+        respondText(200);
+      }
+
+      if (diagnosticsEnabled) {
+        logWebhookProcessed({
+          channel: "telegram",
+          updateType: "telegram-post",
+          durationMs: Date.now() - startTime,
         });
-      return;
+      }
+    })().catch((err) => {
+      const errMsg = formatErrorMessage(err);
+      if (diagnosticsEnabled) {
+        logWebhookError({
+          channel: "telegram",
+          updateType: "telegram-post",
+          error: errMsg,
+        });
+      }
+      runtime.log?.(`webhook handler failed: ${errMsg}`);
+      respondText(500);
+    });
+  });
+
+  await listenHttpServer({
+    server,
+    port,
+    host,
+  });
+
+  const publicUrl = resolveWebhookPublicUrl({
+    configuredPublicUrl: opts.publicUrl,
+    server,
+    path,
+    host,
+    port,
+  });
+
+  try {
+    await withTelegramApiErrorLogging({
+      operation: "setWebhook",
+      runtime,
+      fn: () =>
+        bot.api.setWebhook(publicUrl, {
+          secret_token: secret,
+          allowed_updates: resolveTelegramAllowedUpdates(),
+        }),
+    });
+  } catch (err) {
+    server.close();
+    void bot.stop();
+    if (diagnosticsEnabled) {
+      stopDiagnosticHeartbeat();
     }
-    guard.dispose();
-  });
+    throw err;
+  }
 
-  const publicUrl =
-    opts.publicUrl ?? `http://${host === "0.0.0.0" ? "localhost" : host}:${port}${path}`;
-
-  await withTelegramApiErrorLogging({
-    operation: "setWebhook",
-    runtime,
-    fn: () =>
-      bot.api.setWebhook(publicUrl, {
-        secret_token: secret,
-        allowed_updates: resolveTelegramAllowedUpdates(),
-      }),
-  });
-
-  await new Promise<void>((resolve) => server.listen(port, host, resolve));
   runtime.log?.(`webhook listening on ${publicUrl}`);
 
+  let shutDown = false;
   const shutdown = () => {
+    if (shutDown) {
+      return;
+    }
+    shutDown = true;
+    void withTelegramApiErrorLogging({
+      operation: "deleteWebhook",
+      runtime,
+      fn: () => bot.api.deleteWebhook({ drop_pending_updates: false }),
+    }).catch(() => {
+      // withTelegramApiErrorLogging has already emitted the failure.
+    });
     server.close();
     void bot.stop();
     if (diagnosticsEnabled) {