clean up leftover guild commands in prod and warn about duplicates in dev

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

bot/src/run.py

@@ -74,12 +74,24 @@ class Bot(commands.Bot):
                 name = file[:-3]
                 await self.load_extension(f"cogs.{name}")
 
-        # Sync slash commands
+        # Sync slash commands. A sync only replaces the commands in its own scope, so commands left
+        # in the other scope (global or guild) from running in the other mode show up as duplicates
+        guild = discord.Object(id=self.guild_id)
         if os.environ.get("BOT_CONFIG_MODE") == "prod":
             await self.tree.sync()
+            try:
+                self.tree.clear_commands(guild=guild)
+                await self.tree.sync(guild=guild)
+            except discord.HTTPException as e:
+                self.logger.warning(f"Could not remove leftover guild commands in {self.guild_id}: {e}")
         else:
-            self.tree.copy_global_to(guild=discord.Object(id=self.guild_id))
-            await self.tree.sync(guild=discord.Object(id=self.guild_id))
+            self.tree.copy_global_to(guild=guild)
+            await self.tree.sync(guild=guild)
+            if global_commands := await self.tree.fetch_commands():
+                self.logger.warning(
+                    f"This bot application also has {len(global_commands)} global slash commands, which show up "
+                    + "twice in the dev guild. Use a separate bot application for development"
+                )
 
     async def __aexit__(self, *args):
         """