[BUG] File suggester fails to dismiss after space/newline, causing ENTER to overwrite final word instead of submitting prompt

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Reviving #69823

File suggester fails to dismiss after space/newline, causing ENTER to overwrite final word instead of submitting prompt.

When a user references a path using @~/some/path/ (trailing space) and continues typing a prompt , the autocomplete suggestion context fails to dismiss. Because the suggester remains active, pressing ENTER to submit the prompt is instead trapped by the autocomplete handler, which replaces the last typed word of the query with a path completion.

Steps to Reproduce & Behavioral Matrix

Objective: Reference a directory and ask a question (e.g., @~/some/path/ some question).

The input sequence is prefaced with @~/some/path/

| Input Sequence | Input State | Desired State | Actial State (if different) | Desired Behaviour | Current Behaviour |
| :---------------------------------------------------- | :------------------------------ | :-------------------------------------- | :----------------------------------------------- | :------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------- |
| ENTER | @~/some/pa | @~/some/path/ | | Completes the path. | ✅ Completes the path, even with spaces such as @~/some/path with spaces/ |
| [Space] | @~/some/path/ | @~/some/path/ | | Dismisses suggester, since paths with spaces don't quite work with the autocomplete anyways. | ❌ Dismisses the suggester. |
| [Space] + ENTER | @~/some/path/ | @~/some/path/ | | Submits the promot. | ❌ Dismisses the suggester, but does not submit the prompt. |
| [Space] + [Any Char/Word] + ENTER | @~/some/path/ a question | @~/some/path/ a question | @~/some/path/ a @~/some/path/__pycache__/ | Submits the prompt. | ❌ Suggester stays active. ENTER overwrites the final word. |
| SHIFT+ENTER (Newline) | @~/some/path/ | @~/some/path/<br>\n (empty newline) | | Dismisses suggester. | ❌ Suggester stays active. |
| SHIFT+ENTER (Newline) + [Any Char/Word] + ENTER | @~/some/path/<br>a question | @~/some/path/<br>a question | @~/some/path/<br>a @~/some/path/__pycache__/ | Dismisses suggester, submits the prompt. | ❌ Suggester stays active across newlines. ENTER overwrites the final word on the new line. |

Current Workaround

To bypass the active state trap, users must manually dismiss the suggester before continuing their query:

1. Type @/intended/dir/ + (space).
2. Workaround: Press ENTER (to dismiss).
3. Type the remainder of the prompt.
4. Press ENTER again to submit.

Claude Code Version

2.1.185

Terminal/Shell

Observed in, not limited to; kitty, VSCode, konsole, alacritty

Operating System

Ubuntu/Debian Linux

Feedback ID: 7392d4f0-94da-404c-bc80-75f8c611ce14