ast-grep Search and Refactor

Use this skill when

• regex/rg matching is too fragile
• refactors need placeholder captures ($VAR, $$$ARGS)
• you need language-aware code pattern detection

Decision rule

• Literal text search -> rg
• Syntax tree structure search -> ast-grep

Core workflow

1. Define a minimal structural pattern.
2. Run search scoped to target paths/language.
3. Review match set before rewrite.
4. Apply rewrite interactively or with update-all if safe.
5. Re-run tests/lints after rewrite.

Minimal command set

# Search
ast-grep -p 'pattern' --lang ts src/

# Preview rewrite
ast-grep -p 'old($$$ARGS)' -r 'new($$$ARGS)' --lang ts src/

# Interactive rewrite
ast-grep -p 'old($$$ARGS)' -r 'new($$$ARGS)' --lang ts -i src/

# Apply all rewrites
ast-grep -p 'old($$$ARGS)' -r 'new($$$ARGS)' --lang ts -U src/

Constraints

• Always limit path scope.
• Prefer interactive mode for large rewrites.
• Never run destructive rewrites without a preview.

References

• reference.md
• examples.md
• rules/ (ready-to-use scan rules)