telegram: add error handlers to stop silent polling death

The bot would silently stop delivering messages after the first error:
grammy's default handler calls bot.stop() on any middleware throw, and
void bot.start() / void mcp.notification() swallow rejections with no log.

- bot.catch(): log and keep polling on handler errors
- bot.start().catch(): log when polling dies (bad token, 409, network)
- mcp.notification().catch(): log when inbound delivery to Claude fails
- process-level unhandledRejection/uncaughtException as a safety net

Fixes #756 #759 #761 #777 #809, partial #788

external_plugins/telegram/server.ts

@@ -15,7 +15,7 @@ import {
   ListToolsRequestSchema,
   CallToolRequestSchema,
 } from '@modelcontextprotocol/sdk/types.js'
-import { Bot, GrammyError, InputFile, type Context } from 'grammy'
+import { Bot, InputFile, type Context } from 'grammy'
 import type { ReactionTypeEmoji } from 'grammy/types'
 import { randomBytes } from 'crypto'
 import { readFileSync, writeFileSync, mkdirSync, readdirSync, rmSync, statSync, renameSync, realpathSync, chmodSync } from 'fs'
@@ -51,6 +51,15 @@ if (!TOKEN) {
 }
 const INBOX_DIR = join(STATE_DIR, 'inbox')
 
+// Last-resort safety net — without these the process dies silently on any
+// unhandled promise rejection. With them it logs and keeps serving tools.
+process.on('unhandledRejection', err => {
+  process.stderr.write(`telegram channel: unhandled rejection: ${err}\n`)
+})
+process.on('uncaughtException', err => {
+  process.stderr.write(`telegram channel: uncaught exception: ${err}\n`)
+})
+
 const bot = new Bot(TOKEN)
 let botUsername = ''
 
@@ -577,7 +586,7 @@ async function handleInbound(
 
   // image_path goes in meta only — an in-content "[image attached — read: PATH]"
   // annotation is forgeable by any allowlisted sender typing that string.
-  void mcp.notification({
+  mcp.notification({
     method: 'notifications/claude/channel',
     params: {
       content: text,
@@ -590,38 +599,25 @@ async function handleInbound(
         ...(imagePath ? { image_path: imagePath } : {}),
       },
     },
+  }).catch(err => {
+    process.stderr.write(`telegram channel: failed to deliver inbound to Claude: ${err}\n`)
   })
 }
 
-// 409 Conflict = another getUpdates consumer is still active (zombie from a
-// previous session, or a second Claude Code instance). Retry with backoff
-// until the slot frees up instead of crashing on the first rejection.
-void (async () => {
-  for (let attempt = 1; ; attempt++) {
-    try {
-      await bot.start({
-        onStart: info => {
-          botUsername = info.username
-          process.stderr.write(`telegram channel: polling as @${info.username}\n`)
-        },
-      })
-      return // bot.stop() was called — clean exit from the loop
-    } catch (err) {
-      if (err instanceof GrammyError && err.error_code === 409) {
-        const delay = Math.min(1000 * attempt, 15000)
-        const detail = attempt === 1
-          ? ' — another instance is polling (zombie session, or a second Claude Code running?)'
-          : ''
-        process.stderr.write(
-          `telegram channel: 409 Conflict${detail}, retrying in ${delay / 1000}s\n`,
-        )
-        await new Promise(r => setTimeout(r, delay))
-        continue
-      }
-      // bot.stop() mid-setup rejects with grammy's "Aborted delay" — expected, not an error.
-      if (err instanceof Error && err.message === 'Aborted delay') return
-      process.stderr.write(`telegram channel: polling failed: ${err}\n`)
-      return
-    }
-  }
-})()
+// Without this, any throw in a message handler stops polling permanently
+// (grammy's default error handler calls bot.stop() and rethrows).
+bot.catch(err => {
+  process.stderr.write(`telegram channel: handler error (polling continues): ${err.error}\n`)
+})
+
+bot.start({
+  onStart: info => {
+    botUsername = info.username
+    process.stderr.write(`telegram channel: polling as @${info.username}\n`)
+  },
+}).catch(err => {
+  // bot.start() only rejects if polling can't begin or dies unrecoverably —
+  // bad token, 409 conflict, network gone. Log it so the user isn't left
+  // wondering why messages stopped arriving.
+  process.stderr.write(`telegram channel: polling stopped: ${err}\n`)
+})