fix(@wterm/dom): support IME composition (Japanese/Chinese/Korean input)#50
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sakaritoru wants to merge 3 commits into
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fix(@wterm/dom): support IME composition (Japanese/Chinese/Korean input)#50sakaritoru wants to merge 3 commits into
sakaritoru wants to merge 3 commits into
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IME first keystroke (e.g. typing 'k' to compose 'か') fires keydown with keyCode 229 before compositionstart. Without this guard, the raw latin key is sent to the PTY in addition to the eventual composed character, which breaks Japanese/Chinese/Korean input. Also bail when e.isComposing is true (defense in depth for browsers that surface it on keydown). Refs: w3c/uievents-key#23, xtermjs/xterm.js handles this similarly.
The hidden textarea sits at left:-9999px which means the OS IME inline preview (the candidate window's pre-edit text) is rendered off-screen. Users can compose Japanese/Chinese/Korean but can't see what they're typing until they commit. Mirror xterm.js's approach: keep the textarea at the cursor as an input antenna, and add a separate <span class="term-composition"> overlay that renders the candidate string with the terminal's font and background. The textarea stays opacity:0 so the OS caret never shows through. Lifecycle: compositionstart -> position textarea + show overlay compositionupdate -> overlay textContent = e.data compositionend -> hide overlay + send committed data once A MutationObserver re-positions the textarea when the cursor element moves so subsequent compositions land at the right column.
Full-screen TUIs (Claude Code, vim, less, tmux, etc.) routinely emit
\x1b[?25l to hide the cursor while drawing their own UI. The renderer
removes the .term-cursor element when the cursor is invisible, so
querySelector(".term-cursor") returns null and the composition overlay
ends up at the document origin instead of the prompt position.
Fall back to bridge.getCursor() and resolve a pixel position from the
matching .term-row plus a measured monospace character width. The probe
caches its result unconditionally — an unmeasurable layout (jsdom)
would otherwise re-probe on every observer fire and recurse forever.
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May 10, 2026
…panese/Chinese/Korean input)
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Summary
Adds IME (Input Method Editor) composition support to
@wterm/dom, fixing three independent issues that broke Japanese / Chinese / Korean text entry:keydown(which fires withkeyCode === 229beforecompositionstart) was forwarded to the PTY as a raw character, so commits like `こんにちは` produced `kこんにちは`.Changes
Three atomic commits, all scoped to `packages/@wterm/dom/src/input.ts` and its tests:
No API surface change. No new dependencies. No other packages touched.
Test plan
Notes