add-pattern

Skill: add-pattern

Guide the agent through every step needed to add a new conflict-resolution pattern from end to end, touching all four required locations in the right order.

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Step 1 — Gather information before writing any code

Ask the following questions up front. Do not start editing files until you have clear answers.

1. Name — What is the snake_case name for this pattern? (e.g. comment_only_change, empty_block_insertion)

2. Trigger condition — In plain English, when does this pattern apply? Be precise: what must be true of oursLines, theirsLines, and optionally baseLines for the pattern to fire?

3. Resolution strategy — What should the merged output look like when this pattern fires? (accept ours, accept theirs, union, base + additions, etc.)

4. Confidence score — What typeClassification value (0–100) do you propose, and why? What dataRisk value (0–100, where 0 = safe)? Use the existing patterns as a reference:

   • same_change / one_side_change / delete_no_change → typeClassification 100, dataRisk 0
   • non_overlapping → typeClassification 90, dataRisk 20
   • whitespace_only / reorder_only / insertion_at_boundary → typeClassification 85–90, dataRisk 8–20
   • value_only_change → typeClassification 72–88, dataRisk 25

5. Priority — What numeric priority should this pattern have? Lower = evaluated earlier. Current assignments:

   • 10 same_change, 20 delete_no_change, 30 one_side_change
   • 40 non_overlapping, 50 whitespace_only, 55 reorder_only
   • 57 insertion_at_boundary, 60 value_only_change, 999 complex Pick a value that places it at the right point in the evaluation chain.

6. requires — Does the pattern need the base (diff3), work without it (diff2), or both? Use "diff3", "diff2", or "both".

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Step 2 — Add the ConflictType to types.ts

packages/core/src/types.ts contains the ConflictType union. Add the new type name there before creating the pattern file — TypeScript will then flag every location that needs updating.