`astro-jsx.d.ts` references `KebabKeys`, which `dist/type-utils` does not export (TS2694)

[nerymurillohnd]

Astro Info

Astro                    v7.2.2
Vite                     v8.2.1
Node                     v24.19.0
System                   macOS (arm64)
Package Manager          npm
Output                   server
Adapter                  @astrojs/cloudflare (v14.2.1)
Integrations             @astrojs/svelte (v9.0.1)
                         astro-favicons (v3.1.6)

If this issue only occurs in one browser, which browser is a problem?

No response

Describe the Bug

packages/astro/astro-jsx.d.ts:509 imports a type that type-utils does not export:

type KebabCSSDOMProperties = import('./dist/type-utils.js').KebabKeys<DOMCSSProperties>;

src/type-utils.ts (and the published dist/type-utils.d.ts) export exactly seven types, none of them KebabKeys:

Simplify, WithRequired, OmitIndexSignature, OmitPreservingIndexSignature, ValueOf, MapValue, DeepPartial

The line immediately below it uses Simplify from the same module and resolves fine, so this is not a module-resolution problem — the type simply does not exist. A code search across withastro/astro returns one occurrence of KebabKeys in the whole repository: the consumer above. There is no definition, so this is present on main and not only in the published tarball. It looks like the type was removed or renamed and this reference was left behind.

How to surface it

It is readable in the published package, but to see it in a compile, opt out of skipLibCheck:

// tsconfig.json
{
  "extends": "astro/tsconfigs/strictest",
  "compilerOptions": { "skipLibCheck": false }
}

$ npx tsc --noEmit
node_modules/astro/astro-jsx.d.ts(509,62): error TS2694: Namespace '.../node_modules/astro/dist/type-utils' has no exported member 'KebabKeys'.

It also appears in-editor with no config change at all, because opening astro-jsx.d.ts types it in an inferred project where skipLibCheck does not apply. That is how I ran into it.

Why this has probably stayed invisible

astro/tsconfigs/base.json:25 sets skipLibCheck: true, and both strict.json and strictest.json extend it. Every project on a shipped preset therefore suppresses this error, and it only surfaces if someone opts out or opens the file directly. I could not find an existing issue for it anywhere on GitHub.

Impact — deliberately stated as small

I do not think this breaks anyone's build, and I would rather say so than overstate it. StyleObject is:

type StyleObject = Simplify<KebabCSSDOMProperties & DOMCSSProperties & AllCSSProperties>;

and AllCSSProperties is an index signature accepting any string key, so CSSProperties still accepts everything regardless of what KebabCSSDOMProperties resolves to. The practical loss is autocomplete for kebab-case CSS properties in style={{ … }} objects, plus an erroneous type sitting in the public .d.ts surface that anyone disabling skipLibCheck will hit.

What's the expected result?

astro-jsx.d.ts should reference a type that exists, so that the public .d.ts surface type-checks on its own.

Either:

1. Restore KebabKeys in src/type-utils.ts (if the kebab-case key mapping was meant to stay), or
2. Drop the reference and let DOMCSSProperties and AllCSSProperties carry StyleObject on their own.

Option 2 is the smaller change and, as far as I can tell, changes nothing observable — AllCSSProperties already accepts any string key. Option 1 is the one that restores kebab-case autocomplete, if that was the intent.

Link to Minimal Reproducible Example

astro/packages/astro/astro-jsx.d.ts

Line 509 in c8729fe

type KebabCSSDOMProperties = import('./dist/type-utils.js').KebabKeys<DOMCSSProperties>;

Participation

• I am willing to submit a pull request for this issue.

[astrobot-houston]

• Reproduced: Yes — npx tsc --noEmit with skipLibCheck: false produces TS2694: Namespace '.../dist/type-utils' has no exported member 'KebabKeys'
• Exploration: Yes — View branch
• Unit Test: No — this is a type-level issue in a .d.ts file; the existing pnpm test:types suite passes after the fix
• Priority: P3: minor bug. The error is masked by skipLibCheck: true in all shipped tsconfigs, so it only surfaces for users who explicitly opt out or open astro-jsx.d.ts directly. The practical impact is loss of kebab-case CSS autocomplete in style={{ }} objects.

PR #13591 ("chore: clean dead code") removed the Kebab and KebabKeys type utilities from packages/astro/src/type-utils.ts, but packages/astro/astro-jsx.d.ts:509 still references KebabKeys<DOMCSSProperties>. Because astro-jsx.d.ts is a .d.ts file (not .ts), it was not caught by the dead-code analysis — and because all shipped tsconfigs set skipLibCheck: true, the resulting TS2694 error has been silently suppressed since April 2025.

I found a potential fix for this issue. The fix restores the two removed type utilities (Kebab and KebabKeys) to packages/astro/src/type-utils.ts, which is where astro-jsx.d.ts expects to find them. This is a single-file, 8-line addition that re-exports the exact types that were deleted.

Try this fix

You can test this fix right now without waiting for a release:

npm i https://pkg.pr.new/astro@0b552c2

If this fixes your issue, please leave a comment letting us know (e.g. "confirmed, this fixes it"). We'll then open a pull request to get this merged.

Full Triage Report

Reproduction

With skipLibCheck: false in tsconfig.json (overriding Astro's default base.json which sets it to true), running npx tsc --noEmit produces:

astro-jsx.d.ts(509,62): error TS2694: Namespace '.../dist/type-utils' has no exported member 'KebabKeys'.

The error traces to this line in astro-jsx.d.ts:

type KebabCSSDOMProperties = import('./dist/type-utils.js').KebabKeys<DOMCSSProperties>;

Diagnosis

• Root cause: Commit 5dd2d3fde8 (PR chore: clean dead code #13591, "chore: clean dead code", merged April 2025) removed Kebab and KebabKeys from src/type-utils.ts.
• Why it was missed: astro-jsx.d.ts is a hand-written .d.ts file, not a compiled .ts file, so it wasn't analyzed by the dead-code tooling. Additionally, skipLibCheck: true in all shipped tsconfigs suppresses the error.
• Impact: KebabCSSDOMProperties silently resolves to any, which means kebab-case CSS property names (e.g. background-color) no longer get autocomplete in style={{ }} objects. The AllCSSProperties index signature ([key: string]: ...) still allows any string key, so no type errors occur in user code — only the autocomplete enhancement is lost.

Verification

• pnpm test:types passes after the fix.
• npx tsc --noEmit with skipLibCheck: false no longer reports TS2694 for KebabKeys.
• grep 'KebabKeys' packages/astro/dist/type-utils.d.ts confirms the type is present in the built output.

Fix

Restored the two type utilities in packages/astro/src/type-utils.ts:

export type Kebab<T extends string, A extends string = ''> = T extends `${infer F}${infer R}`
	? Kebab<R, `${A}${F extends Lowercase<F> ? '' : '-'}${Lowercase<F>}`>
	: A;

export type KebabKeys<T> = { [K in keyof T as K extends string ? Kebab<K> : K]: T[K] };

These are the exact definitions that existed before PR #13591 removed them.

This report was made by an LLM. The analysis may be wrong, and the potential fix might not work, but is intended as a starting point for exploring the issue.