fix(discord): Register slash commands globally only (#804)

Register Discord slash commands only at global scope so the same commands are not also created per guild. This keeps slash commands available in DMs and prevents duplicate entries in guild command pickers.

Co-authored-by: Rapi-agent <rapi-agent@users.noreply.github.com>

Author: jacklau1993

src/discord.rs

@@ -865,20 +865,25 @@ impl EventHandler for Handler {
                 )),
         ];
 
-        // Register global commands (works in DMs + all guilds after propagation).
+        // Register global commands only. Registering the same commands per-guild
+        // makes Discord show duplicate slash commands in guild command pickers.
         if let Err(e) = Command::set_global_commands(&ctx.http, commands.clone()).await {
             tracing::warn!(error = %e, "failed to register global slash commands");
         } else {
             info!("registered global slash commands");
         }
 
-        // Also register per-guild for instant availability (global can take up to 1h).
+        // One-time migration cleanup: older versions registered the same
+        // slash commands per-guild, and Discord persists those server-side.
+        // Keep guild command sets empty so only global commands are shown.
         for guild in &ready.guilds {
             let guild_id = guild.id;
-            if let Err(e) = guild_id.set_commands(&ctx.http, commands.clone()).await {
-                tracing::warn!(%guild_id, error = %e, "failed to register guild slash commands");
-            } else {
-                info!(%guild_id, "registered guild slash commands");
+            if let Err(e) = guild_id.set_commands(&ctx.http, Vec::new()).await {
+                tracing::warn!(
+                    %guild_id,
+                    error = %e,
+                    "failed to clear stale guild slash commands"
+                );
             }
         }