[BUG] Claude Code (Claude Desktop app): IME composition Enter advances one step too many in code diff inline comment input (consumes IME confirm and comment-edit confirm together)

Summary

In Claude Code running inside the Claude Desktop app, in the code diff inline comment input, a single Enter pressed to confirm a Japanese / CJK IME conversion is consumed as both "IME composition confirm" and "comment-edit confirm" at the same time, advancing the input state one step further than intended.

The target UI surface is the small comment input that appears anchored to a line when you select a line (or range) in a code diff view. It shows a Line N reference label at the top and an Add a comment placeholder in the input — the same UI surface referred to as "code diff inline comments" in #49387.

When used together with a Japanese IME, this input should behave as a three-step Enter flow:

1. Enter (1st): confirm the IME composition (e.g., nihongo → 日本語)
2. Enter (2nd): confirm the comment edit (lock the comment as a draft anchored to the line)
3. Enter (3rd): send the comment

In the current build, however, the first Enter performs ① IME composition confirm and ② comment-edit confirm simultaneously, so the second Enter already sends the comment. The Enter sequence effectively skips one step.

This is the same class of bug (missing composition-aware Enter handling) as #59319, propagated to a UI surface that was not covered by that fix. The main chat input, AskUserQuestion "Other" free-text input, Plan mode inline comment input, and session rename input were all fixed in earlier patches; the same fix has not been propagated to the code diff inline comment input.

Steps to Reproduce

1. In Claude Code (Claude Desktop app), open a code diff view (e.g., right after Claude proposes a code change)
2. Select a line (or range) in the diff to open the inline comment input — the one with the Line N reference label and the Add a comment placeholder
3. Switch to a Japanese IME and type e.g. nihongo
4. Press Enter (1st) to confirm the IME composition into 日本語
5. Press Enter (2nd)

Expected (the intended three-step flow)

| Enter | Expected behavior |
|---|---|
| 1st | Only confirm the IME composition. The comment edit state stays active. |
| 2nd | Confirm the comment edit (commit the draft anchored to the line). |
| 3rd | Send the comment. |

Actual (the current two-step behavior)

| Enter | Actual behavior |
|---|---|
| 1st | IME composition confirm and comment-edit confirm fire together (the two steps collapse into one). |
| 2nd | The comment is sent immediately. |

As a result, pressing Enter twice while typing Japanese sends a comment that would only be expected to fire on the third Enter.

Cross-check with already-fixed surfaces

On the same build, the following surfaces handle IME composition Enter correctly:

• Main chat input
• AskUserQuestion "Other" free-text input (verified fixed since #27764 / #36537)
• Plan mode inline comment input (fixed in #59319)
• Session rename input (fixed in #59319)

The composition-aware Enter handling exists in the codebase; it just has not been propagated to the code diff inline comment input.

Duplicate check vs. existing issues

I searched for prior reports targeting this specific UI surface and found none. The closest existing issues are listed below and all target different UI surfaces or environments:

| Issue | Target UI | State | Difference from this issue |
|---|---|---|---|
| #59319 | Plan inline comment input + session rename | closed (fixed) | Different UI surface (Plan body / sidebar). This report is the code diff comment field. |
| #36537 | Plan "Revise" popup + AskUserQuestion Other | closed (fixed) | Different UI surface (Revise popup, not the diff-initiated inline comment field). |
| #27764 | AskUserQuestion "Other" | closed (verified fixed in practice) | Different UI surface. |
| #8405 | VS Code extension chat input | closed (fixed) | Different environment (VS Code extension). |
| #42995 | claude.ai/code on Chrome | open | Different environment (Web). |
| #48257 | VS Code integrated terminal (xterm.js) | open | Different environment (TUI). |
| #48209 | CLI slash-command input (Ghostty) | open | Different environment (CLI). |
| #53890 | Korean IME trailing character (CLI) | open | Different environment (CLI). |

No existing issue currently covers the code diff inline comment input in the Claude Desktop app.

Environment

• Claude Code in Claude Desktop app, macOS
• Build: Claude Desktop 1.8555.2 (a476c3), built 2026-05-22T23:04:37.000Z — the latest build at the time of this report
• Japanese IME

The build above already includes the #59319 fix for the Plan inline comment input and session rename input, but the same composition-aware Enter handling has not been propagated to the code diff inline comment input, so the bug reproduces.