"Transform to Snake Case" does nothing on kebab case text

[brcrista]

Type: Bug

1. Open a file or new tab
2. Enter some text in kebab case, such as "hello-this-is-kebab-case"
3. Highlight the text and run the "Transform to Snake Case" command

Expected: text becomes "hello_this_is_kebab_case"
Actual: text remains "hello-this-is-kebab-case"

Other notes:

• I've observed this since July 2025
• Snake->kebab and kebab->camel->snake both work

VS Code version: Code 1.108.1 (Universal) (585eba7, 2026-01-14T14:55:44.241Z)
OS version: Darwin arm64 25.1.0
Modes:

System Info

Item	Value
CPUs	Apple M1 (8 x 2400)
GPU Status	2d_canvas: enabled 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: enabled_on trees_in_viz: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	3, 3, 5
Memory (System)	8.00GB (0.07GB free)
Process Argv	--disable-extensions --crash-reporter-id d71a2944-66c1-42ac-8e34-5d821de1e82e
Screen Reader	no
VM	0%

Extensions disabled

A/B Experiments

vsliv368cf:30146710
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31436602
aj953862:31281341
6abeh943:31336334
cloudbuttont:31379625
3efgi100_wstrepl:31403338
use-responses-api:31390855
anonusage:31403420
ec5jj548:31422691
cp_cls_c_966_ss:31446431
c0683394:31419495
a5gib710:31434435
7a04d226_do_not_restore_last_panel_session:31438103
anthropic_thinking_t:31432745
h0hdh950:31428394
cp_cls_c_1081:31443829
nes-set-to-on:31441941
a43f0575b:31442825

[brcrista]

• Code pointer:

  vscode/src/vs/editor/contrib/linesOperations/browser/linesOperations.ts

  Line 1243 in 7d96fc6

  public static caseBoundary = new BackwardsCompatibleRegExp('(\\p{Ll})(\\p{Lu})', 'gmu');

• Test:

  vscode/src/vs/editor/contrib/linesOperations/test/browser/linesOperations.test.ts

  Line 930 in 7d96fc6

  const snakecaseAction = new SnakeCaseAction();

[RedCMD]

the TextMate snippets work

vscode/src/vs/editor/contrib/snippet/browser/snippetParser.ts

Lines 455 to 459 in 97b81ef

	private _toSnakeCase(value: string): string {
	return value.replace(/([a-z])([A-Z])/g, '$1_$2')
	.replace(/[\s\-]+/g, '_')
	.toLowerCase();
	}

just not the linesOperations command

[Milad93R]

I'd like to work on this issue. I'll submit a PR with the fix shortly.