astvcs-add-tree-sitter-language

name	astvcs-add-tree-sitter-language
description	Adds or extends tree-sitter language support in astvcs. Use when adding a file extension, wiring a tree-sitter grammar, editing src/frontend, or when the user mentions a new language, parser, or AST translation for a source file type.
paths	["src/frontend/**","Cargo.toml","docs/architecture.md"]
metadata	{"project":"astvcs"}

Add tree-sitter language support

Gather

1. Confirm the extension is not already listed in docs/architecture.md.
2. Find a maintained tree-sitter-* crate on crates.io compatible with tree-sitter = "0.26.9".
3. Read src/frontend/languages.rs, src/frontend/treesitter.rs, and supported_extensions() in src/lib.rs.

Act

1. Cargo.toml

Add the tree-sitter-<lang> dependency. Pin a crates.io version that builds with the repo's tree-sitter.

2. SourceLanguage enum (languages.rs)

• Add a variant.
• Map extensions in from_path (case-sensitive; use substring after the last .).
• For basename-only manifests (for example go.mod), match file_name() before the extension rule and list the path in supported_special_paths().
• Return the grammar in tree_sitter_language().
• Extend unit tests in the same file for extension detection.

3. Translator (treesitter.rs)

Wire the grammar into the existing visitor. Reuse NodeKind mappings where the AST shape matches an existing language. Add kind mappings only when tree-sitter node types differ. Leading trivia gaps use the previous sibling's rightmost leaf end byte (see last_leaf_end_byte in treesitter.rs).

4. Public API (lib.rs)

Add the extension string to supported_extensions(), or the basename to supported_special_paths() when there is no stable extension.

5. Docs

Add the extension and language to the table in docs/architecture.md.

6. Integration test (tests/integration.rs)

Add a (path, source) sample to parse_all_supported_languages. Every extension from supported_extensions() and every path from supported_special_paths() must have a sample or the test fails.

Example entry:

("main.rb", "def main\nend\n"),

Extension rules

• types.d.ts maps to .ts, not a separate extension.
• Unsupported extensions and parse failures fall back to text with warning: on stderr.
• Only UTF-8 text paths are tracked.

Verify

cargo test parse_all_supported_languages
cargo test
cargo clippy --all-targets --all-features -- -D warnings

Round-trip check when unparser coverage exists:

cargo test rust_unparse_roundtrip go_unparse_roundtrip