Windows Japanese IME preedit text is not visible and candidate window is offset

[snuffxxx]

Discord username (optional)

No response

Describe the bug

On Windows, Japanese IME input does not render the preedit / composing text correctly in Warp, and the IME candidate window appears offset above the actual input area instead of near the caret/composition position.

This still reproduces on the latest Warp version after trying the common input/font workarounds.

To Reproduce

1. Open Warp on Windows.
2. Use Japanese IME in the normal Warp input area.
3. Type Japanese text and start IME conversion.
4. Observe the composing text and candidate window position.

Expected behaviour

• The Japanese IME composing/preedit text should be visible while converting.
• The IME candidate window should appear at the current caret/composition position.

Screenshots

I have a screenshot showing the candidate window appearing above the input area. I can attach it manually if needed.

Operating System

Windows

OS Version

10.0.26200

Shell Version

No response

Warp Version

v0.2026.04.29.08.57.stable_01

Additional context

I tried the following, but the issue still reproduces:

• Updated Warp to the latest version
• Switched to Classic Input / Shell (PS1)
• Changed Input position
• Set a Japanese-capable font

This does not appear to be a shell, font, or input mode configuration issue. It looks related to Windows IME marked text rendering and IME candidate window positioning.

Related issue: #320

Does this block you from using Warp daily?

Yes

[oz-for-oss]

@snuffxxx

This issue appears to overlap with existing issues:

• Support marked text for international text input #320 — Support marked text for international text input
• Warp 的 Windows 输入层没有实现 IME 预编辑字符串的捕获和渲染，导致拼音输入的"中间状态"对用户不可见。 #9012 — Warp 的 Windows 输入层没有实现 IME 预编辑字符串的捕获和渲染，导致拼音输入的"中间状态"对用户不可见。
• Japanese IME conversion candidates popup is misaligned from cursor/input line #9145 — Japanese IME conversion candidates popup is misaligned from cursor/input line

If this report is meaningfully different, please comment with the additional context or distinguishing behavior so a maintainer can review it. Otherwise, a maintainer may close it as a duplicate after review.

Maintainer details

I concluded that windows Japanese IME composing text is hidden and the candidate popup is misplaced, matching existing IME marked-text and candidate-positioning reports..

Duplicate reasoning

• Support marked text for international text input #320: This is the broad open tracker for rendering IME marked/composing text, which matches the incoming report's invisible Japanese IME preedit text.
• Warp 的 Windows 输入层没有实现 IME 预编辑字符串的捕获和渲染，导致拼音输入的"中间状态"对用户不可见。 #9012: This reports missing Windows IME preedit capture/rendering that makes the composing state invisible, matching the incoming Windows IME preedit symptom.
• Japanese IME conversion candidates popup is misaligned from cursor/input line #9145: This reports the Japanese IME candidate window appearing away from the cursor/input line, matching the incoming candidate-window offset symptom.

This is my automated analysis and may be incorrect. A maintainer will verify the details.

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[snuffxxx]

Additional information: I confirmed that this is not specific to one IME.

The same symptoms reproduce with all of the following on Windows:

• Microsoft Japanese IME
• Google Japanese Input
• Copilot Keyboard

In all cases, the Japanese IME preedit / composing text is not shown correctly, and the candidate window appears offset above the actual input area instead of near the caret/composition position.