feat: auto-respond in bot-created Discord threads (#144)

* feat: auto-respond in bot-created Discord threads (#77)

Messages sent in Discord threads created by this bot now trigger the
agent automatically — no @mention required, same as DMs.

**Changes to handleMessage:**
- Detect thread messages via `message.channel.isThread()`
- For threads, resolve the parent channel JID for group lookup (threads
  aren't registered groups, but their parent channels are)
- Bot filter block updated to also use parent channel JID for threads
  (preserves per-group trigger patterns for agent-to-agent comms)
- Auto-trigger logic: if `message.channel.ownerId === botId`, prepend
  trigger and thread context (`[In thread: <name>]`) to the message
- Responses currently go to the parent channel; full in-thread reply
  routing can be added in a follow-up PR

**Not changed:**
- Thread registration: no new DB entries needed
- Message storage: thread messages stored under parent channel JID
- Reactions and other Discord events: unaffected

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix(discord): address CodeRabbit review issues in PR #144

- Use per-group trigger name/pattern for auto-trigger in bot threads
  (fixes multi-agent setups where group trigger differs from ASSISTANT_NAME)
- Check original content before prepending thread context to avoid
  potential double trigger prefix edge case
- Fix mentionsOtherUsersOnly TS2345 error: add botId != null guard
  so Map.has() receives string (not string | undefined)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Peyton-Spencer

src/channels/discord.ts

@@ -443,20 +443,29 @@ export class DiscordChannel implements Channel {
       }
     }
 
+    const isDM = message.channel.type === ChannelType.DM;
+
+    // Detect thread messages: route via parent channel for group lookup
+    const isThread = !isDM && message.channel.isThread();
+    const threadParentId = isThread && message.channel.parent
+      ? message.channel.parent.id
+      : null;
+
     // Allow bot messages through only if they contain our trigger (agent-to-agent comms).
     // This prevents infinite loops — bots must explicitly @mention us.
     // Use per-channel trigger so agent-to-agent comms work across multi-agent servers.
+    // For threads, resolve the parent channel's group for the trigger pattern.
     {
-      const _isDM = message.channel.type === ChannelType.DM;
-      const _chatJid = _isDM
+      const _chatJid = isDM
         ? `dc:dm:${message.author.id}`
-        : `dc:${message.channelId}`;
+        : isThread && threadParentId
+          ? `dc:${threadParentId}`
+          : `dc:${message.channelId}`;
       const _group = getAllRegisteredGroups()[_chatJid];
       const _triggerPattern = buildTriggerPattern(_group?.trigger);
       if (message.author.bot && !_triggerPattern.test(content)) return;
     }
 
-    const isDM = message.channel.type === ChannelType.DM;
     // In guild channels, only process messages that mention THIS bot OR reply to the bot.
     // Prevents responding when another agent (e.g. @PeytonOmni) is mentioned instead.
     const isReplyToBot = message.mentions.repliedUser?.id === botId;
@@ -498,9 +507,13 @@ export class DiscordChannel implements Channel {
       }
     }
 
+    // For thread messages, route via parent channel JID so we find the registered group.
+    // Responses go to the parent channel (thread-reply routing is a future enhancement).
     const chatJid = isDM
       ? `dc:dm:${message.author.id}`
-      : `dc:${message.channelId}`;
+      : isThread && threadParentId
+        ? `dc:${threadParentId}`
+        : `dc:${message.channelId}`;
 
     const timestamp = message.createdAt.toISOString();
     const senderName =
@@ -631,6 +644,19 @@ export class DiscordChannel implements Channel {
           'Reply to bot — treating as triggered',
         );
         content = `@${ASSISTANT_NAME} ${content}`;
+      } else if (isThread && message.channel.ownerId === botId) {
+        // Auto-trigger in threads created by this bot — no @mention needed.
+        // Use per-group trigger name for consistency with multi-agent setups.
+        const threadName = message.channel.name || 'thread';
+        const agentName = group?.trigger?.replace(/^@/, '') || ASSISTANT_NAME;
+        const groupTriggerPattern = buildTriggerPattern(group?.trigger);
+        logger.info({ chatJid, threadId: message.channelId, threadName, sender: senderName }, 'Auto-triggering in bot-created thread');
+        // Check original content before prepending thread context to avoid double trigger prefix
+        const hasGroupTrigger = groupTriggerPattern.test(content);
+        content = `[In thread: ${threadName}] ${content}`;
+        if (!hasGroupTrigger) {
+          content = `@${agentName} ${content}`;
+        }
       } else if (this.shouldAutoRespond(content, group)) {
         logger.debug(
           {