How AST-grep Rewrote Tree-sitter in Rust and Made It 30% Faster

# Summary ast-grep rewrote Tree-sitter's C core in Rust using AI-assisted code generation, achieving a 30% faster parsing speed and 22% overall performance improvement in ast-grep's end-to-end execution. The Rust version outperformed the original C implementation in parsing throughput and tree traversal, though it uses slightly more memory (8 MiB additional in typical use). The narrower runtime was optimized specifically for AI coding agents analyzing complete file snapshots rather than serving as a full replacement for the original Tree-sitter ecosystem.