telegram: exit when Claude Code closes the connection

When the MCP stdio transport closes, the bot kept polling Telegram as
a zombie process — holding the token and causing 409 Conflict for the
next session.

- Listen for stdin end/close and SIGTERM/SIGINT -> bot.stop() + exit
- Force-exit after 2s if bot.stop() stalls on the long-poll timeout
- unref the approval-check interval so it doesn't keep us alive

Fixes #793, partial #788 (issue 3)

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'
@@ -304,7 +304,7 @@ function checkApprovals(): void {
   }
 }
 
-if (!STATIC) setInterval(checkApprovals, 5000)
+if (!STATIC) setInterval(checkApprovals, 5000).unref()
 
 // Telegram caps messages at 4096 chars. Split long replies, preferring
 // paragraph boundaries when chunkMode is 'newline'.
@@ -507,6 +507,24 @@ mcp.setRequestHandler(CallToolRequestSchema, async req => {
 
 await mcp.connect(new StdioServerTransport())
 
+// When Claude Code closes the MCP connection, stdin gets EOF. Without this
+// the bot keeps polling forever as a zombie, holding the token and blocking
+// the next session with 409 Conflict.
+let shuttingDown = false
+function shutdown(): void {
+  if (shuttingDown) return
+  shuttingDown = true
+  process.stderr.write('telegram channel: shutting down\n')
+  // bot.stop() signals the poll loop to end; the current getUpdates request
+  // may take up to its long-poll timeout to return. Force-exit after 2s.
+  setTimeout(() => process.exit(0), 2000)
+  void Promise.resolve(bot.stop()).finally(() => process.exit(0))
+}
+process.stdin.on('end', shutdown)
+process.stdin.on('close', shutdown)
+process.on('SIGTERM', shutdown)
+process.on('SIGINT', shutdown)
+
 bot.on('message:text', async ctx => {
   await handleInbound(ctx, ctx.message.text, undefined)
 })
@@ -593,35 +611,9 @@ async function handleInbound(
   })
 }
 
-// 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: ${err}\n`)
-      return
-    }
-  }
-})()
+void bot.start({
+  onStart: info => {
+    botUsername = info.username
+    process.stderr.write(`telegram channel: polling as @${info.username}\n`)
+  },
+})