edit-deterministic

name	edit-deterministic
description	Offload mechanical and type-aware edits to deterministic tools instead of LLM file-rewrites (P2). Use ast-grep --rewrite for repeated/mechanical transforms and Serena replace_symbol for single type-aware symbol edits. Apply whenever a change is rule-shaped rather than judgment-shaped.

Deterministic Edit Skill (P2)

Purpose

Minimize LLM file-rewrites. If an edit follows a rule, a tool should apply it — verifiably and reversibly (invariant: cheap to verify, cheap to roll back).

Decision

• Mechanical / repeated across many sites → ast-grep --rewrite (preview first).
• Single, type-aware symbol (rename/replace a function/method body) → Serena replace_symbol.
• Genuine judgment (novel logic, one-off) → LLM Edit, smallest diff, match surrounding code.

ast-grep --rewrite (mechanical)

# ALWAYS dry-run first — no -U/--update-all
ast-grep -p 'foo($A)' --rewrite 'bar($A)' --lang ts        # preview diff
ast-grep -p 'foo($A)' --rewrite 'bar($A)' --lang ts -U     # apply after review

Serena (type-aware, single symbol)

• find_symbol → locate the exact symbol (no whole-file read).
• replace_symbol_body → swap one definition, LSP-aware.
• Single MCP; use only when enabled. Absent → fall back to scoped Edit.
• Large repos: serena project index first; turn it off for tiny modules (startup cost).
• Kotlin escape hatch (ADR-005) — Serena's standard LSP can be flaky on Kotlin (slow startup). For deep Kotlin/Spring symbol work, the IntelliJ/JetBrains backend is the gold standard; switch to it only when the standard LSP misbehaves (it's paid + IDE-bound, so not the default).
• Verified findings worth keeping go to .serena/memories (human-reviewed, P5) — not auto-injected.

Rules

• Preview every --rewrite before applying; commit boundary around it (P6).
• Re-confirm target in one shot before a multi-site change (P3), then verify (scripts/verify.sh).
• Optional tools may be absent — degrade to a minimal manual Edit, never block.

Need rewrite/replace patterns and worked examples? Read references/patterns.md.