feat: add discord.reactions config option to disable message reactions (#4199)

Adds a 'reactions' key under the discord config section (default: true).
When set to false, the bot no longer adds 👀/✅/❌ reactions to messages
during processing. The config maps to DISCORD_REACTIONS env var following
the same pattern as require_mention and auto_thread.

Files changed:
- hermes_cli/config.py: Add reactions default to DEFAULT_CONFIG
- gateway/config.py: Map discord.reactions to DISCORD_REACTIONS env var
- gateway/platforms/discord.py: Gate on_processing_start/complete hooks
- tests/gateway/test_discord_reactions.py: 3 new tests for config gate

gateway/config.py

@@ -550,6 +550,8 @@ def load_gateway_config() -> GatewayConfig:
                     os.environ["DISCORD_FREE_RESPONSE_CHANNELS"] = str(frc)
                 if "auto_thread" in discord_cfg and not os.getenv("DISCORD_AUTO_THREAD"):
                     os.environ["DISCORD_AUTO_THREAD"] = str(discord_cfg["auto_thread"]).lower()
+                if "reactions" in discord_cfg and not os.getenv("DISCORD_REACTIONS"):
+                    os.environ["DISCORD_REACTIONS"] = str(discord_cfg["reactions"]).lower()
 
             # Telegram settings → env vars (env vars take precedence)
             telegram_cfg = yaml_cfg.get("telegram", {})

gateway/platforms/discord.py

@@ -683,14 +683,22 @@ class DiscordAdapter(BasePlatformAdapter):
             logger.debug("[%s] remove_reaction failed (%s): %s", self.name, emoji, e)
             return False
 
+    def _reactions_enabled(self) -> bool:
+        """Check if message reactions are enabled via config/env."""
+        return os.getenv("DISCORD_REACTIONS", "true").lower() not in ("false", "0", "no")
+
     async def on_processing_start(self, event: MessageEvent) -> None:
         """Add an in-progress reaction for normal Discord message events."""
+        if not self._reactions_enabled():
+            return
         message = event.raw_message
         if hasattr(message, "add_reaction"):
             await self._add_reaction(message, "👀")
 
     async def on_processing_complete(self, event: MessageEvent, success: bool) -> None:
         """Swap the in-progress reaction for a final success/failure reaction."""
+        if not self._reactions_enabled():
+            return
         message = event.raw_message
         if hasattr(message, "add_reaction"):
             await self._remove_reaction(message, "👀")