unity-diff-workflow

Skill: unity-diff-workflow

Use this skill when comparing Unity .prefab, .unity, or .asset files — across versions, variants, or branches.

When to use this skill

• "What changed in this prefab?"
• "How does EnemyBat differ from EnemyWolf?"
• "What did this PR change in the scene?"
• "Show me what the variant overrides from the base prefab"

Workflow

Comparing two separate prefabs

1. parse_unity_file on file A with preset: "compact"
2. parse_unity_file on file B with preset: "compact"
3. Diff the two YAML outputs — focus on components, field values, hierarchy shape

Comparing a prefab variant to its base

Variants already show only their differences — no manual diff needed:

1. parse_unity_file on the variant with preset: "compact"
2. The output includes variant_of: BasePrefabName and modification markers:
   • # $ — field modified from base
   • # + — component or GameObject added
   • # - — component removed from base

Comparing across git branches/versions

1. Parse the current version: parse_unity_file on the current file
2. Parse the old version: git show <commit>:<path> to a temp file, then parse_unity_file on it
3. Diff the two compact YAML outputs

Diff reading guide

Focus on these sections when diffing:

• hierarchy — shape changes (added/removed GameObjects, reparenting)
• components — added/removed component types per GameObject
• Field values within components — value changes

Ignore noise:

• lPos: (0, 0, 0), lScale: (1, 1, 1) — default transforms, omitted in compact
• enabled: true — omitted in compact
• Internal Unity fields (m_ObjectHideFlags, etc.) — always filtered

Token strategy for large diffs

For large prefabs or scenes, scope the diff:

• Use componentWhitelist to compare only specific components:

  { "preset": "compact", "componentWhitelist": ["Rigidbody2D", "CircleCollider2D"] }
  

• Use includeHierarchy: false to skip hierarchy and focus on component data:

  { "preset": "compact", "includeHierarchy": false }