fix: address review feedback for ReactionCog

- Use time.monotonic() at reaction time instead of stale message-receive timestamp
- Add excluded_channels config and filtering
- Truncate message content to 500 chars in pick_reaction

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

cogs/reactions.py

@@ -28,6 +28,13 @@ class ReactionCog(commands.Cog):
         if not message.content or not message.content.strip():
             return
 
+        # Channel exclusion
+        excluded = cfg.get("excluded_channels", [])
+        if excluded:
+            ch_name = getattr(message.channel, "name", "")
+            if message.channel.id in excluded or ch_name in excluded:
+                return
+
         # RNG gate
         chance = cfg.get("chance", 0.15)
         if random.random() > chance:
@@ -41,9 +48,9 @@ class ReactionCog(commands.Cog):
             return
 
         # Fire and forget so we don't block anything
-        asyncio.create_task(self._try_react(message, ch_id, now))
+        asyncio.create_task(self._try_react(message, ch_id))
 
-    async def _try_react(self, message: discord.Message, ch_id: int, now: float):
+    async def _try_react(self, message: discord.Message, ch_id: int):
         try:
             emoji = await self.bot.llm.pick_reaction(
                 message.content, message.channel.name,
@@ -52,7 +59,7 @@ class ReactionCog(commands.Cog):
                 return
 
             await message.add_reaction(emoji)
-            self._last_reaction[ch_id] = now
+            self._last_reaction[ch_id] = time.monotonic()
             logger.info(
                 "Reacted %s to %s in #%s: %s",
                 emoji, message.author.display_name,

config.yaml

@@ -166,3 +166,4 @@ reactions:
   enabled: true
   chance: 0.15          # Probability of evaluating a message for reaction
   cooldown_seconds: 45  # Per-channel cooldown between reactions
+  excluded_channels: []  # Channel names or IDs to skip reactions in

utils/llm_client.py

@@ -782,7 +782,7 @@ class LLMClient:
                     model=self.model,
                     messages=[
                         {"role": "system", "content": prompt},
-                        {"role": "user", "content": f"[#{channel_name}] {message_text}"},
+                        {"role": "user", "content": f"[#{channel_name}] {message_text[:500]}"},
                     ],
                     **temp_kwargs,
                     max_completion_tokens=16,