fix: 채널 중복 완전 해결 - Discord 캐시 대신 자체 dict로 이름 검색

bot.py

@@ -195,7 +195,7 @@ class GravityBot(commands.Bot):
     async def _ensure_channel(
         self, conversation_id: str, project_name: str
     ) -> discord.TextChannel:
-        """Get or create a channel. Uses GLOBAL lock and NAME-based lookup."""
+        """Get or create a channel. Uses GLOBAL lock + OWN dict lookup (no cache issues)."""
         # Fast path: already mapped
         if conversation_id in self.session_channels:
             return self.session_channels[conversation_id]
@@ -208,24 +208,16 @@ class GravityBot(commands.Bot):
             channel_name = f"{Config.CHANNEL_PREFIX}-{project_name}"
             target_name = channel_name.lower().replace(" ", "-")
 
-            # Fetch FRESH channel list from Discord API (not cached)
-            if self.session_category:
-                category = await self.guild.fetch_channel(self.session_category.id)
-                for ch in category.text_channels:
-                    # Match by NAME (handles different conv IDs → same project)
-                    if ch.name == target_name or (ch.topic and conversation_id in ch.topic):
+            # Check OWN dict for a channel with the same NAME
+            # (different conv IDs can share one channel)
+            for cid, ch in self.session_channels.items():
+                if ch.name == target_name:
                     self.session_channels[conversation_id] = ch
                     self.session_names[conversation_id] = project_name
-                        # Rename from closed- if needed
-                        if ch.name.startswith("closed-"):
-                            try:
-                                await ch.edit(name=channel_name)
-                            except discord.errors.Forbidden:
-                                pass
-                        logger.info(f"Reusing existing channel #{ch.name}")
+                    logger.info(f"Reusing channel #{ch.name} for {conversation_id[:8]}")
                     return ch
 
-            # Create new channel (only if truly no match found)
+            # Create new channel (truly first time)
             try:
                 channel = await self.guild.create_text_channel(
                     name=channel_name,
@@ -280,10 +272,16 @@ class GravityBot(commands.Bot):
         if not channel:
             return
 
+        try:
             if event.file_name == "task.md":
                 await self._send_task_update(channel, event)
             else:
                 await self._send_artifact_update(channel, event)
+        except discord.NotFound:
+            # Channel was deleted while we held a reference
+            self.session_channels.pop(event.conversation_id, None)
+            self.session_status_messages.pop(event.conversation_id, None)
+            logger.warning(f"Channel deleted, cleared: {event.conversation_id[:8]}")
 
     # ─── Message Senders ─────────────────────────────────────────────