feat(discord): support forum channels

gateway/channel_directory.py

@@ -100,7 +100,7 @@ def build_channel_directory(adapters: Dict[Any, Any]) -> Dict[str, Any]:
 
 
 def _build_discord(adapter) -> List[Dict[str, str]]:
-    """Enumerate all text channels the Discord bot can see."""
+    """Enumerate all text channels and forum channels the Discord bot can see."""
     channels = []
     client = getattr(adapter, "_client", None)
     if not client:
@@ -119,6 +119,15 @@ def _build_discord(adapter) -> List[Dict[str, str]]:
                 "guild": guild.name,
                 "type": "channel",
             })
+        # Forum channels (type 15) — creating a message auto-spawns a thread post.
+        forums = getattr(guild, "forum_channels", None) or []
+        for ch in forums:
+            channels.append({
+                "id": str(ch.id),
+                "name": ch.name,
+                "guild": guild.name,
+                "type": "forum",
+            })
         # Also include DM-capable users we've interacted with is not
         # feasible via guild enumeration; those come from sessions.
 
@@ -191,6 +200,15 @@ def load_directory() -> Dict[str, Any]:
         return {"updated_at": None, "platforms": {}}
 
 
+def lookup_channel_type(platform_name: str, chat_id: str) -> Optional[str]:
+    """Return the channel ``type`` string (e.g. ``"channel"``, ``"forum"``) for *chat_id*, or *None* if unknown."""
+    directory = load_directory()
+    for ch in directory.get("platforms", {}).get(platform_name, []):
+        if ch.get("id") == chat_id:
+            return ch.get("type")
+    return None
+
+
 def resolve_channel_name(platform_name: str, name: str) -> Optional[str]:
     """
     Resolve a human-friendly channel name to a numeric ID.