GitHub language detection and highlighting

GitHub uses Linguist to classify source files and select highlighting grammars. Installing the Twill VSIX changes your editor; it does not install a grammar on GitHub.

Highlighting now

Add these lines to the root .gitattributes in each repository containing Twill source, then commit and push the file:

*.twill linguist-language=TypeScript
*.twillx linguist-language=TSX

The patterns also apply to files in subdirectories, subject to more specific attribute overrides. GitHub's documented language overrides select the existing TypeScript and TSX grammars. Their names are registered in Linguist's language definitions.

This provides base-language highlighting without changing our extensions. Twill-specific constructs such as defer, guard and trailing-closure parameter headers use whatever the TypeScript grammar recognizes; this is not the dedicated Twill grammar. Language statistics classify these files as TypeScript (TSX belongs to that language group), rather than a new Twill language. Normal vendored, documentation and generated-file exclusions still apply.

Markdown fences do not inherit .gitattributes. Use typescript or tsx fences for now. A twill fence or linguist-language=Twill cannot install an unregistered language or grammar.

Check local Git attributes with:

git check-attr linguist-language -- src/main.twill src/view.twillx

This verifies attribute selection, not GitHub's rendered page. GitHub controls deployment and refresh timing.

Recognition status

Twill is not registered as a separate GitHub language. The TypeScript/TSX overrides above are the supported setup today; use typescript or tsx in GitHub Markdown fences.

Official recognition requires an upstream Linguist review, sufficient public adoption and GitHub deployment. See Linguist's language policy for the requirements. A dedicated Twill grammar in VS Code does not change this status.