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

@@ -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'.
@@ -507,61 +507,23 @@ mcp.setRequestHandler(CallToolRequestSchema, async req => {
 
 await mcp.connect(new StdioServerTransport())
 
-// Commands are DM-only. Responding in groups would: (1) leak pairing codes via
-// /status to other group members, (2) confirm bot presence in non-allowlisted
-// groups, (3) spam channels the operator never approved. Silent drop matches
-// the gate's behavior for unrecognized groups.
-
-bot.command('start', async ctx => {
-  if (ctx.chat?.type !== 'private') return
-  const access = loadAccess()
-  if (access.dmPolicy === 'disabled') {
-    await ctx.reply(`This bot isn't accepting new connections.`)
-    return
-  }
-  await ctx.reply(
-    `This bot bridges Telegram to a Claude Code session.\n\n` +
-    `To pair:\n` +
-    `1. DM me anything — you'll get a 6-char code\n` +
-    `2. In Claude Code: /telegram:access pair <code>\n\n` +
-    `After that, DMs here reach that session.`
-  )
-})
-
-bot.command('help', async ctx => {
-  if (ctx.chat?.type !== 'private') return
-  await ctx.reply(
-    `Messages you send here route to a paired Claude Code session. ` +
-    `Text and photos are forwarded; replies and reactions come back.\n\n` +
-    `/start — pairing instructions\n` +
-    `/status — check your pairing state`
-  )
-})
-
-bot.command('status', async ctx => {
-  if (ctx.chat?.type !== 'private') return
-  const from = ctx.from
-  if (!from) return
-  const senderId = String(from.id)
-  const access = loadAccess()
-
-  if (access.allowFrom.includes(senderId)) {
-    const name = from.username ? `@${from.username}` : senderId
-    await ctx.reply(`Paired as ${name}.`)
-    return
-  }
-
-  for (const [code, p] of Object.entries(access.pending)) {
-    if (p.senderId === senderId) {
-      await ctx.reply(
-        `Pending pairing — run in Claude Code:\n\n/telegram:access pair ${code}`
-      )
-      return
-    }
-  }
-
-  await ctx.reply(`Not paired. Send me a message to get a pairing code.`)
-})
+// 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)
@@ -653,13 +615,5 @@ void bot.start({
   onStart: info => {
     botUsername = info.username
     process.stderr.write(`telegram channel: polling as @${info.username}\n`)
-    void bot.api.setMyCommands(
-      [
-        { command: 'start', description: 'Welcome and setup guide' },
-        { command: 'help', description: 'What this bot can do' },
-        { command: 'status', description: 'Check your pairing status' },
-      ],
-      { scope: { type: 'all_private_chats' } },
-    ).catch(() => {})
   },
 })