[BUG] `/` no longer opens the slash-command menu mid-message — only at index 0 (regressed in 2.1.247, last good 2.1.246)

Hi, and thanks for all the work on Claude Code — it has become a core part of my daily workflow, skills especially.

Filing this as a regression rather than a feature request: the behaviour did work for me until recently, and the desktop app's own logs let me narrow it down to a single version step, so I have included that below in case it saves you a bisect. Apologies if I have missed an existing report — I searched, and the closest matches are feature requests for the TUI rather than reports that something stopped working.

## Preflight

- [x] Searched existing issues
- [x] Single bug report
- [x] Using the latest version

## What's Wrong?

Typing `/` no longer opens the slash-command / skill menu unless `/` is at **index 0 of the message**. After any preceding character, `/` is inserted as a literal slash and no menu appears.

Precise scope:

1. **Bound to index 0, not to the start of a line.** In a multi-line message, `/` as the first character of the second line does nothing either.
2. **Not limited to skills.** Nothing in that menu is reachable mid-message — built-in commands, plugin commands and file-based skills from `~/.claude/skills/` alike.
3. **The menu itself is healthy.** At index 0 it opens and lists everything correctly. This is not #48963 / #49148 (entries missing from the picker) — only the trigger position.
4. **Invocation still works, discovery doesn't.** Typing a skill name in full mid-message still gets picked up and run. Only the menu is gone.
5. **Both surfaces.** Reproduced in the Claude Code desktop app and in the terminal CLI.

This used to work: until **~2026-08-29** the menu opened wherever `/` was typed, mid-sentence included. Nothing changed on my side — no reinstall, no settings change, no plugin change.

## What Should Happen?

`/` typed at a **word boundary** — start of the message, or immediately after whitespace or a newline — opens the menu, filters as I keep typing, and inserts the selection at the caret, leaving surrounding text intact.

`/` inside a token stays silent: `src/utils`, `and/or`, `http://`.

## Steps to Reproduce

1. Any session with at least one skill in `~/.claude/skills/`.
2. Type `/` as the first character of the message. → Menu opens, lists commands and skills. **Works.**
3. Clear the input. Type `review this ` and then `/`. → Literal `/` inserted, no menu. **Broken.**
4. With the caret still at the end, jump to index 0 (`Cmd+←` / Home) and type `/`. → Menu opens. **Works.**
5. Clear the input. Type `review this`, insert a newline (`Shift+Enter`), then type `/` as the first character of the second line. → Literal `/` inserted, no menu. **Broken.**

## Is this a regression?

**Yes.**

## Last Working Version

**2.1.246.** First bad version: **2.1.247**.

From this machine's desktop-app logs, which record every embedded-CLI bundle install:

```
2026-08-26 11:46:30 installed 2.1.246
2026-08-28 18:56:54 installed 2.1.247
2026-09-01 22:15:02 installed 2.1.255
```

2.1.246 ran from Aug 26 to Aug 28 and the menu worked throughout. 2.1.247 landed the evening of Aug 28 and would have been picked up on the next app launch — which matches when I noticed the behavior change, ~Aug 29. So the regression window is exactly **2.1.246 → 2.1.247**.

The 2.1.247 changelog contains one entry that touches slash-command detection:

> Fixed prompts beginning with `/--` … being rejected as an unknown slash command instead of being sent to Claude

That is the obvious suspect: a fix that tightens *what counts as a slash command* is the kind of change that could also tighten *where the menu is allowed to trigger*.

Possibly also relevant, though it landed after the onset (I only reached it with 2.1.255 on Sep 1) — 2.1.250:

> Changed the action menu to list slash commands in a filterable "Slash commands" dialog instead of inline; picking one runs it

## Claude Code Version

`2.1.257` (terminal CLI) and `2.1.255` (embedded in Claude desktop app 1.40609.1). Both reproduce.

## Platform

Anthropic API

## Operating System

macOS 26.4 (build 25E246, arm64)

## Terminal/Shell

Terminal.app (zsh with oh-my-zsh). Also reproduced in the Claude Code desktop app, which is not a terminal.

## Error Messages/Logs

None. No console error accompanies the failed trigger — the keystroke is simply inserted as text.

## Additional Information

A note on the date, in case the bisect matters: I first estimated "about a week ago" and later placed it at ~Aug 29. If the onset were in fact Aug 26, the window would instead be 2.1.241 → 2.1.246 (2.1.241 was installed 2026-08-26 00:30, 2.1.246 at 11:46 the same day). My confidence is on Aug 29 and therefore on 2.1.247.

Related: #13073, #29752, #40413, #44488, #48963, #49148, #55173 — note that the mid-prompt requests among these were evaluated as feature requests for the TUI, whereas this is a report that working behavior stopped.

Start by reproducing the slash-command trigger in the terminal CLI, comparing behavior at the 2.1.246 and 2.1.247 version boundary. Trace the slash-command detection and action-menu entry points; done means the menu opens at message start and after whitespace or a newline, remains silent inside tokens, and preserves the existing index-0 behavior.

Rédigé par le modèle d'indexation à partir du texte de l'issue.