Korean (Hangul) IME composition in integrated terminal pushes/duplicates a line

Type: Bug

▎ 환경: VS Code 1.134.0 (user setup), Electron 42.8.1, Windows 10
▎
▎ 재현 방법:
▎ 1. 통합 터미널을 연다 (PowerShell 프로필이든 Command Prompt 프로필이든 동일하게 재현됨 — 셸 무관)
▎ 2. 한글 IME로 텍스트 입력 (예: "가늠" 등 조합 중인 상태)
▎ 3. 조합 중인 글자 위/근처에 불필요한 문자(예: 이전 입력 잔상)가 삽입되며 아래 줄들이 밀려 내려감
▎
▎ 확인한 사항:
▎ - 완전히 동일한 셸(cmd.exe, PowerShell)을 VS Code 밖의 독립 창에서 실행하면 문제 없음 → OS/IME 자체 문제 아님
▎ - --disable-extensions로 모든 확장 끄고 재현 → 확장 프로그램 문제 아님
▎ - 아래 설정을 모두 시도했으나 변화 없음:
▎ - terminal.integrated.gpuAcceleration: "off"
▎ - terminal.integrated.shellIntegration.enabled: false
▎ - terminal.integrated.suggest.enabled: false
▎ - terminal.integrated.stickyScroll.enabled: false
▎ - terminal.integrated.unicodeVersion: "6"
▎ - 리부트 직후(아마 자동 업데이트 직후)부터 발생 시작 — 최근 버전 회귀 가능성

VS Code version: Code 1.134.0 (110a328ea54b42367b803ec53ee0bf52ef26b419, 2026-08-18T18:24:44Z)
OS version: Windows_NT x64 10.0.18363
Modes:

System Info

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) i5-9400F CPU @ 2.90GHz (6 x 2904)|
|GPU Status|2d_canvas: enabled
GPU0: VENDOR= 0x10de, DEVICE=0x1c82 [NVIDIA GeForce GTX 1050 Ti], DRIVER_VENDOR=NVIDIA, DRIVER_VERSION=32.0.15.8266 *ACTIVE*
GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.18362.356
Machine model name:
Machine model version:
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_graphite: disabled_off
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgpu: enabled
webnn: disabled_off|
|Load (avg)|undefined|
|Memory (System)|15.95GB (7.27GB free)|
|Process Argv|--crash-reporter-id be4ea2ea-2701-4b31-813d-135fd8f81165|
|Screen Reader|no|
|VM|0%|
Extensions (4)

Name|Identifier|Author|Version
---|---|---|---
Claude Code for VS Code|anthropic.claude-code|Anthropic|2.1.238
Go|golang.go|golang|0.56.0
SFTP|liximomo.sftp|liximomo|1.12.10
Korean Language Pack for Visual Studio Code|ms-ceintl.vscode-language-pack-ko|MS-CEINTL|1.131.2026072717

A/B Experiments

```
vsliv368cf:30146710
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31463988
aj953862:31281341
82j33506:31327384
envsactivate1:31551504
478i5457:31544283
cloudbuttont:31379625
3efgi100_wstrepl:31403338
839jf696:31457053
ec5jj548:31422691
cp_cls_t_966_ss:31526232
4je02754:31466945
c3h7c220:31478652
cp_cls_c_1081:31454833
conptydll_true:31498968
e9c30283:31461165
test_treatment2:31471001
46204921:31447328
ei9d7968:31496641
chat:31457767
ghj88844:31499326
ddid_t:31478206
hmra_i5g22:31518061
7df3h592:31512476
cp_cls_t_1082:31535311
logging_enabled_new:31498466
db5d2638:31499441
jb_cp_cls_t_632:31543129
748c7209:31512887
32d76977:31512328
ha629193:31508444
a1ije391_t:31540920
jbcp_cls_pctr_t:31531130
61138546:31518536
cp_intellij_t_nes:31548657
gf14b233:31526830
ahp-both-windows:31556933
session_8:31532895
ihg5j128:31534457
f412h606:31551416
7g2b5551:31542111
enable_editor_pane_layout:31569726
allow-none:31555437
6i51c363:31551401
ac562147:31564510
c7c27ce7:31554789
1h923230:31564177
0dg73464:31554319
treatment-23-1:31555779
unuse_dynamic_mcp:31555281
0d8dfbc3:31570291
switchtoauto:31559321
0c1h4866:31566224
vrbsty_fls:31561059
session-mark-done:31558131
5b8j3302:31564601

```