fix(#709): route Discord threads and approvals

plugins/discord/src/index.ts

@@ -327,15 +327,18 @@ export class DiscordPlugin {
       },
       this.config.serviceToken,
     );
-    this.socket.emit('message', envelope);
+    this.socket.emit(content.startsWith('/approve ') ? 'discord:approve' : 'message', envelope);
   }
 
   private isAllowedMessage(message: DiscordMessage): boolean {
     const guildId = message.guildId;
+    const parentChannelId = 'parentId' in message.channel ? message.channel.parentId : null;
+    // Threads inherit their authorization boundary from their configured parent.
+    const authorizationChannelId = parentChannelId ?? message.channelId;
     return (
       guildId !== null &&
       includesId(this.config.allowedGuildIds, guildId) &&
-      includesId(this.config.allowedChannelIds, message.channelId) &&
+      includesId(this.config.allowedChannelIds, authorizationChannelId) &&
       includesId(this.config.allowedUserIds, message.author.id)
     );
   }