ln-33-code-modernizer
Code Modernizer
Goal: Modernize a bounded capability only when the new design measurably reduces human workflow friction, maintenance, risk, dependency duplication, or delivered artifact cost. Preserve behavior, isolate migrations, and revert changes that do not create net value.
Execution contract: Treat the ordered checkbox workflow below as this skill's Definition of Done. Work through every item in order, and mark it complete only when its action and required evidence are complete. N/A, skipped, unavailable, or delegated items remain incomplete.
Before returning, apply this skill's verdict, decision, and approval rules to every incomplete item and prepend Checklist: X/Y completeIncomplete: None | section/item — reason; outcome impact; exact next action; list every incomplete item.
Tool Routing
| Need | Preferred tool | Use it when | Fallback |
|---|---|---|---|
| Current mechanism and consumers | Native file search plus language server or host-native code intelligence | Mapping contracts, callers, configuration, data, lifecycle, and tests | Narrow import, symbol, route, and configuration search with direct reads |
| Existing platform capabilities | Manifests, lockfiles, runtime APIs, and current official documentation | Avoiding new dependencies or custom code for an already available feature | Repository examples and source inspection; mark capability UNVERIFIED if current docs are unavailable |
| External replacement candidates | Official package registries, source repositories, documentation, releases, advisories, and license data | Comparing maintained software with custom implementation | Primary-source web research; do not rely on popularity lists alone |
| Baseline and value | Build output, bundle analysis, code inventory, benchmark, defects, or maintenance evidence | Defining what modernization must improve | Reproducible static counts with documented scope and limitations |
| Safe migration | Git isolation, focused edits, native package manager, and repository generation commands | Replacing one bounded capability and its consumers | Stop if user changes or generated state cannot be protected |
| Verification | Repository-defined build, lint, type, test, smoke, packaging, and runtime checks | Before migration and after every retained step | Add a focused compatibility test when existing coverage cannot prove the contract |
| Delivered artifact analysis | Existing bundle analyzer, size report, startup profile, or dependency report | Bundle size, load path, or runtime cost is part of the goal | Build artifact comparison with reproducible file and compression rules |