Syntax Definition

Syntax Definition

Use this skill when asked to create or update a syntax definition for a named language or file format.

Goal

Create or update exactly one grammar file in the repository top-level syntaxes/ directory:

• syntaxes/<Language>.sublime-syntax

Also create or update one fixture/expectations pair under tests/fixtures/syntaxes/<language>/:

• <sample>.<ext>
• <sample>.<ext>.tokens.yml

Examples:

• JSON -> syntaxes/JSON.sublime-syntax
• TypeScript -> syntaxes/TypeScript.sublime-syntax
• Elm -> syntaxes/Elm.sublime-syntax
• Dockerfile -> syntaxes/Dockerfile.sublime-syntax

If a matching file already exists, update it instead of creating a duplicate.

Required Constraints

• Only produce Sublime Text 3 compatible grammars.
• Do not use Sublime Text 4+ only syntax features.
• Keep the file as YAML with the usual .sublime-syntax structure.
• Do not write the grammar anywhere except the top-level syntaxes/ directory unless the user explicitly asks for something else.
• Keep syntax regression fixtures under tests/fixtures/syntaxes/.

When compatibility is uncertain, prefer conservative syntax features:

• %YAML 1.2
• name
• file_extensions
• scope
• variables
• contexts
• match
• captures
• scope
• push
• set
• pop
• include
• meta_scope
• meta_content_scope

Workflow

1. Identify the requested language or format name.
2. Inspect nearby files in syntaxes/ to match the repository's existing style and naming conventions.
3. Create a practical first-pass grammar with the core building blocks for that language:
   • comments
   • strings
   • numbers
   • keywords
   • operators or punctuation
   • identifiers
4. Add one representative sample file under tests/fixtures/syntaxes/<language>/.
5. Add a YAML expectations file named <sample>.<ext>.tokens.yml with:
   • buffer_path: the virtual filename used to select the syntax
   • expectations: an ordered list of critical (text, scope) checks
6. Run cargo test syntaxes to test and fix issues with the generated/updated syntax.

Output guidelines

For generated/updated syntaxes

• Use a stable top-level scope such as source.<language> or text.<format> as appropriate.
• Keep contexts readable and modular rather than over-optimizing the grammar.
• If the language details are incomplete, make the smallest reasonable set of assumptions and state them briefly.
• The resulting syntax file should be directly usable by the repository's syntax-loading code.
• Prefer correctness and compatibility over advanced grammar tricks.

For syntax fixtures

• Use critical-scope expectations only; do not snapshot every token unless the user explicitly asks for exhaustive coverage.
• The fixture should be directly usable by the repository's scribe::Workspace.current_buffer_tokens() test harness.