Dashboard: /fork command passed to LLM instead of intercepted

[Hrovatin]

Summary

When a user types /fork in the dashboard composer and submits, the command is passed to the LLM instead of being intercepted. The LLM recognizes it as a built-in command but generates a fake acknowledgment rather than executing it. No actual fork is created.

Current Behavior

1. User types /fork in the dashboard composer
2. Text is sent via api.prompt() → session.prompt()
3. Built-in commands are not handled by session.prompt() (only extensions, skills, templates)
4. Text reaches the LLM as regular user input
5. LLM's thinking shows confusion: "Actually, looking at this more carefully, '/fork' is likely a built-in dreb command that the system handles, not something I need to process."
6. LLM outputs fake acknowledgment: "Forking this conversation. You'll have a separate branch..."
7. No fork is created — /resume doesn't show the fork

Expected Behavior

When user types /fork in the dashboard composer:

• Option A: Intercept the command and trigger the fork modal (same as clicking the fork button)
• Option B: Show an error/hint that fork should be accessed via the button
• At minimum: Do not pass built-in commands to the LLM

Root Cause

The TUI intercepts /fork in the UI layer (interactive-mode.ts:2305-2308) before calling session.prompt():

if (text === "/fork") {
    this.showUserMessageSelector();
    this.editor.setText("");
    return;
}

The dashboard has a dedicated button-based fork flow (fork button → modal → RPC), but does not intercept /fork text submitted via composer. Built-in commands are also not included in the get_commands RPC response, so the autocomplete doesn't show /fork as an option.

Relevant Files

• packages/dashboard/src/client/screens/session.tsx — Composer submit handling, fork modal
• packages/dashboard/src/server/server.ts — RPC endpoints
• packages/coding-agent/src/modes/interactive/interactive-mode.ts:2305 — TUI reference implementation

Acceptance Criteria

• Typing /fork in dashboard composer does not send the command to the LLM
• Either triggers the fork modal OR shows user-friendly guidance
• Same pattern should apply to other built-in TUI commands that have dashboard equivalents

[Acters]

The question is if we want to have all the slash commands available on the dashboard. currently, only the skill files are slashable. (mostly because of the LLM doing a suggest_next to ask me to use the skill)

I personally would not care about having /fork in the dashboard. on the other hand, adding all commands to the dashboard as slash-able can add some level of unneeded complexity and future code maintenance.

[m-aebrer]

I think if the commands have to be supported one by one, this is not worth it.

If the commands can all be included automatically, including new ones, via a better approach, then I think we should do it, because it will be very low effort.

[Hrovatin]

I find these commands important, so if there is a way to port all would be in favour.