discord: port resilience fixes from telegram

Same patterns as #812/#813 for the discord channel:
- process-level unhandledRejection/uncaughtException handlers
- client.on('error') to log discord.js errors
- mcp.notification().catch() so inbound delivery failures surface
- stdin close / SIGTERM -> client.destroy() + exit (zombie fix)
- .unref() the approval-check interval
- client.login().catch() to log+exit on bad token instead of crashing

Discord is inherently more resilient than telegram (discord.js
auto-reconnects, no 409 equivalent), but these gaps were still there.

external_plugins/discord/server.ts

@@ -58,6 +58,15 @@ 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(`discord channel: unhandled rejection: ${err}\n`)
+})
+process.on('uncaughtException', err => {
+  process.stderr.write(`discord channel: uncaught exception: ${err}\n`)
+})
+
 const client = new Client({
   intents: [
     GatewayIntentBits.DirectMessages,
@@ -342,7 +351,7 @@ function checkApprovals(): void {
   }
 }
 
-if (!STATIC) setInterval(checkApprovals, 5000)
+if (!STATIC) setInterval(checkApprovals, 5000).unref()
 
 // Discord caps messages at 2000 chars (hard limit — larger sends reject).
 // Split long replies, preferring paragraph boundaries when chunkMode is
@@ -637,6 +646,25 @@ mcp.setRequestHandler(CallToolRequestSchema, async req => {
 
 await mcp.connect(new StdioServerTransport())
 
+// When Claude Code closes the MCP connection, stdin gets EOF. Without this
+// the gateway stays connected as a zombie holding resources.
+let shuttingDown = false
+function shutdown(): void {
+  if (shuttingDown) return
+  shuttingDown = true
+  process.stderr.write('discord channel: shutting down\n')
+  setTimeout(() => process.exit(0), 2000)
+  void Promise.resolve(client.destroy()).finally(() => process.exit(0))
+}
+process.stdin.on('end', shutdown)
+process.stdin.on('close', shutdown)
+process.on('SIGTERM', shutdown)
+process.on('SIGINT', shutdown)
+
+client.on('error', err => {
+  process.stderr.write(`discord channel: client error: ${err}\n`)
+})
+
 client.on('messageCreate', msg => {
   if (msg.author.bot) return
   handleInbound(msg).catch(e => process.stderr.write(`discord: handleInbound failed: ${e}\n`))
@@ -685,7 +713,7 @@ async function handleInbound(msg: Message): Promise<void> {
   // forgeable by any allowlisted sender typing that string.
   const content = msg.content || (atts.length > 0 ? '(attachment)' : '')
 
-  void mcp.notification({
+  mcp.notification({
     method: 'notifications/claude/channel',
     params: {
       content,
@@ -698,6 +726,8 @@ async function handleInbound(msg: Message): Promise<void> {
         ...(atts.length > 0 ? { attachment_count: String(atts.length), attachments: atts.join('; ') } : {}),
       },
     },
+  }).catch(err => {
+    process.stderr.write(`discord channel: failed to deliver inbound to Claude: ${err}\n`)
   })
 }
 
@@ -705,4 +735,7 @@ client.once('ready', c => {
   process.stderr.write(`discord channel: gateway connected as ${c.user.tag}\n`)
 })
 
-await client.login(TOKEN)
+client.login(TOKEN).catch(err => {
+  process.stderr.write(`discord channel: login failed: ${err}\n`)
+  process.exit(1)
+})

external_plugins/telegram/server.ts

@@ -372,11 +372,6 @@ mcp.setRequestHandler(ListToolsRequestSchema, async () => ({
             items: { type: 'string' },
             description: 'Absolute file paths to attach. Images send as photos (inline preview); other types as documents. Max 50MB each.',
           },
-          format: {
-            type: 'string',
-            enum: ['text', 'markdownv2'],
-            description: "Rendering mode. 'markdownv2' enables Telegram formatting (bold, italic, code, links). Caller must escape special chars per MarkdownV2 rules. Default: 'text' (plain, no escaping needed).",
-          },
         },
         required: ['chat_id', 'text'],
       },
@@ -403,11 +398,6 @@ mcp.setRequestHandler(ListToolsRequestSchema, async () => ({
           chat_id: { type: 'string' },
           message_id: { type: 'string' },
           text: { type: 'string' },
-          format: {
-            type: 'string',
-            enum: ['text', 'markdownv2'],
-            description: "Rendering mode. 'markdownv2' enables Telegram formatting (bold, italic, code, links). Caller must escape special chars per MarkdownV2 rules. Default: 'text' (plain, no escaping needed).",
-          },
         },
         required: ['chat_id', 'message_id', 'text'],
       },
@@ -424,8 +414,6 @@ mcp.setRequestHandler(CallToolRequestSchema, async req => {
         const text = args.text as string
         const reply_to = args.reply_to != null ? Number(args.reply_to) : undefined
         const files = (args.files as string[] | undefined) ?? []
-        const format = (args.format as string | undefined) ?? 'text'
-        const parseMode = format === 'markdownv2' ? 'MarkdownV2' as const : undefined
 
         assertAllowedChat(chat_id)
 
@@ -452,7 +440,6 @@ mcp.setRequestHandler(CallToolRequestSchema, async req => {
               (replyMode === 'all' || i === 0)
             const sent = await bot.api.sendMessage(chat_id, chunks[i], {
               ...(shouldReplyTo ? { reply_parameters: { message_id: reply_to } } : {}),
-              ...(parseMode ? { parse_mode: parseMode } : {}),
             })
             sentIds.push(sent.message_id)
           }
@@ -495,13 +482,10 @@ mcp.setRequestHandler(CallToolRequestSchema, async req => {
       }
       case 'edit_message': {
         assertAllowedChat(args.chat_id as string)
-        const editFormat = (args.format as string | undefined) ?? 'text'
-        const editParseMode = editFormat === 'markdownv2' ? 'MarkdownV2' as const : undefined
         const edited = await bot.api.editMessageText(
           args.chat_id as string,
           Number(args.message_id),
           args.text as string,
-          ...(editParseMode ? [{ parse_mode: editParseMode }] : []),
         )
         const id = typeof edited === 'object' ? edited.message_id : args.message_id
         return { content: [{ type: 'text', text: `edited (id: ${id})` }] }