App launcher allows entering broken slash command mode when legacy chat is enabled

[hampuskraft]

Description

I want to report an inconsistency in how Discord handles slash commands in legacy chat input mode. To be clear: I'm not reporting that slash commands don't work in legacy mode (that's expected and documented). Instead, I've found that while Discord correctly prevents entering slash command input mode in two ways (by typing "/" or by clicking on command mentions), there's a third way that isn't properly blocked: using the new App Launcher button.

The App Launcher on the right side of the chat input still lets users enter a "slash command input" mode that shouldn't be accessible at all. This puts the chat input into a broken state where the slash command UI gets stuck until manually dismissed, and any attempts to use the command just send regular text messages instead.

Steps to Reproduce

1. Turn on "Use the legacy chat input" in Discord's Accessibility settings
2. Go to any channel where you can send messages and use commands
3. Look for the App Launcher button (it's on the right side of the chat input)
4. Click it and pick any application command
5. Try to use the command — you'll notice you can't actually input any arguments
6. Try hitting enter to submit — it'll just send as regular text

Expected Behavior

Since legacy chat input mode has limited support for application commands, the App Launcher should handle commands based on their argument requirements:

• For commands needing arguments: Don't allow entering slash command input mode, and instead show the "Why don't I see application commands?" modal we get when typing "/"
• For commands that take no arguments: Keep the current behavior of letting users select and submit these directly from the launcher modal, since these work fine without needing the argument input interface

Current Behavior

Right now, the App Launcher creates a confusing situation:

1. It lets us start a slash command (which shouldn't be possible in legacy mode)
2. The command UI gets stuck to our chat input
3. We can't actually use the command — typing just creates regular text
4. We have to manually click the X to get rid of the command UI
5. We don't get any explanation about why things aren't working

Screenshots/Videos

Kapture.2024-12-05.at.12.16.42.mp4

Client and System Information

• Discord Client: Discord Canary 350598 (94428bd)
• Operating System: macOS 15.0 (Build 24A335) on Apple Silicon
• Browser: Firefox Developer Edition 134.0b4 (Build ID: 20241202091515)
• Feature State: "Use the legacy chat input" enabled in Accessibility settings