[BUG] Built-in /diff pane holds mod toasts, undocumented and contradicted by the screen map

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

The built-in /diff mod opens its pane with holdToasts: true (mods/diff/hooks/register.ts), so every $.ui.toast from another mod stays hidden until /diff closes. Nothing on the docs site says so.

The screen map shows the toast in the transcript's top-right corner beside the pane, as if both stay visible:

<img width="600" height="336" alt="Image" src="https://github.com/user-attachments/assets/c13fa28c-fddb-42d9-b2d0-fbb6051020ef" />

The overview's built-in mods table says cc-plugin-diff "takes over /diff and draws its pane", and holdToasts appears only as an option of $.ui.open. To show a toast while /diff is open, a mod has to hook ui.open for { id: 'diff' } and strip holdToasts:

on('ui.open', { id: 'diff' }, async (_$, e, next) => {
  const { holdToasts, ...pane } = e
  return next(pane)
})

What Should Happen?

Any of these:

• /diff shows toasts from mods
• the built-in mods table notes that /diff holds toasts
• the toast docs or the screen map say that an open pane can hold toasts

Steps to Reproduce

1. Load a mod that calls $.ui.toast('hello', { timeoutMs: 60000 }) on a timer.
2. Run /diff to open the pane.
3. The toast doesn't appear until /diff closes.

Claude Model

Opus (Opus 5.5)

Is this a regression?

No, this never worked

Claude Code Version

2.1.287 (Claude Code)

Platform

Anthropic API

Operating System

Debian 13.7

Terminal/Shell

Other (Ghostty)

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