Microsoft/vscode

VSCode Integrated Terminal IME Issue

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#267568 opened on Sep 20, 2025

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Description

Summary

  • The VSCode integrated terminal (backed by xterm.js) consumes raw key events instead of the text committed by the macOS IME.
  • In the macime one-hand Hangul mode, keys such as q (and the mirrored row 0, 9, 8, p, o, i, ;, l, k, , → 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) are remapped inside libhangul. Regular text fields receive the composed character (\u0007008, etc.), but the terminal keeps the original key because it bypasses the IME composition result. In the terminal this shows up as q→q, w→w, a→a, s→s, z→z, x→x, whereas the expected mapping is q→〈, w→〉, a→「, s→,, z→」, x→..

Reproduction Steps

  1. Activate macime and switch to the one-hand Hangul keyboard (HangulInputContext(keyboard: "1hand-right")).
  2. Open VSCode and focus the Integrated Terminal (Ctrl+` or View > Terminal).
  3. With the IME active, type any of the remapped left-hand keys (q, w, a, s, z, x).
  4. Compare the output with the same keys typed in another application (e.g., TextEdit).

Expected vs Actual

  • Expected: The terminal should receive the committed Hangul character that libhangul produces for q in one-hand mode (e.g., \u3008).
  • Actual: The terminal shows the raw Latin q, confirming it ignored the IME-composed output; only the true composition keys (e, r, t, y, u, d, f, g, h, j, c, v, b, n, m, 5, 6, 7) yield Hangul characters in the terminal.

Environment Notes

  • macOS 12.7.6 (Build 21H1320), Intel x86_64 hardware, with accessibility permissions granted to macime.
  • VSCode 1.104.1 (Commit 0f0d87fa9e96c856c5212fc86db137ac0d783365, x64 build).
  • One-hand Hangul layout uses HangulKit/libhangul/hangul/hangulkeyboard.h tables (project repo: https://github.com/Dev0June/macime @ 68190e0117f27ec541836c2fc283de9343a5b590).
  • One-hand English layout is handled separately via macime/KeyMapper.swift, but this path is disabled while the Hangul context is active.
  • Issue reproduces only in VSCode’s xterm.js terminal (and other xterm.js hosts such as Hyper); Chrome, TextEdit, and iTerm handle the IME output correctly.

iterm2

vscode terminal

Contributor guide

Tech stack
typescriptjavascript
Domain
frontenddeveloper experienceinternationalization
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Familiarity with VSCode extension architectureUnderstanding of macOS IME handlingBasic knowledge of xterm.js key events
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Investigate how VSCode's terminal integration with xterm.js handles IME composition events on macOS. Look at the key event pipeline in src/vs/workbench/contrib/terminal/browser/terminal.ts and xterm.js's InputHandler. The issue suggests that xterm.js consumes raw key events instead of the committed text. A possible approach is to intercept the compositionend event or use the beforeinput event. The assignee is likely working on a fix; check for any ongoing work. The maintainers may need to decide whether to fix in VSCode or upstream xterm.js.