Limit rule update to small channels

cogs/aimod_cog.py

@@ -49,6 +49,10 @@ from .aimod_config import (
 )
 
 
+# Avoid loading an excessive number of messages when updating rules
+MAX_RULE_MESSAGES = 25
+
+
 class AIModerationCog(commands.Cog):
     """
     A Discord Cog that uses Google Vertex AI to moderate messages based on server rules.
@@ -753,9 +757,18 @@ class AIModerationCog(commands.Cog):
     ) -> None:
         """Pull the server rules from a channel and update the global config."""
         messages = []
-        async for msg in channel.history(limit=None, oldest_first=True):
+        async for msg in channel.history(
+            limit=MAX_RULE_MESSAGES + 1, oldest_first=True
+        ):
             if msg.content:
                 messages.append(msg.content)
+            if len(messages) > MAX_RULE_MESSAGES:
+                await interaction.response.send_message(
+                    f"Channel has more than {MAX_RULE_MESSAGES} messages."
+                    " Please consolidate your rules into fewer messages.",
+                    ephemeral=True,
+                )
+                return
 
         if not messages:
             await interaction.response.send_message(