logic-diff
Compare two code versions for semantic equivalence via semi-formal tracing of both versions side-by-side.
Logic-Lens — Semantic Diff
When to Use
Use this skill when you need compare two code versions for semantic equivalence via semi-formal tracing of both versions side-by-side. Trigger when the user shares a refactor, rewrite, migration, or A/B implementation and wants to confirm behavior is unchanged — "did I break anything", "is this equivalent", "are...
Setup
Use lazy loading per ../_shared/common.md §13:
- Read
../_shared/common.mdonly for language, Iron Law, Verdict header, scope routing, Remedy discipline, config fields, and loading budget. - Read only the relevant step in
logic-diff-guide.mdas you reach it. - Load
../_shared/logic-risks.md,../_shared/semiformal-guide.md,../_shared/semiformal-checklist.md, and../_shared/report-template.mdon demand when the current step needs them.
Process
Step 0. Language + scope routing. Detect language per common.md §1. Confirm two versions are provided. If only one version, switch to logic-review.
Step 1. Identify the shared specification (guide Step 1) — what inputs should both versions handle; what outputs/side effects are expected. If the user states the refactor intentionally changed behavior in a specific area (e.g., "I changed the error path to raise instead of returning None"), record that as a declared spec change and treat divergences within that area as expected. Flag only
Subscribers only
The full skill, its 2 bundled files and every download is included with every paid Complete AI plan.
Details
| Source | hyhmrright/logic-lens |
|---|---|
| License | MIT |
| Risk label | safe ("critical" means the skill may run commands or touch files — read before use) |
| Files | SKILL.md, logic-diff-guide.md |
| Added | 2026-07-01 |
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