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ln-33-code-modernizer

Modernizes bounded code capabilities by replacing obsolete mechanisms with verified lower-cost designs.

556|83|Updated Oct 24, 2025
Search Tags:#rollback#bundle size#technical debt#legacy code#Refactoring#code modernization#dependency migration
One-click install
npx skills add https://github.com/levnikolaevich/claude-code-skills --skill ln-33-code-modernizer
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: ln-33-code-modernizer
Source: https://github.com/levnikolaevich/claude-code-skills/tree/main/plugins/optimization-suite/skills/ln-33-code-modernizer
Command: npx skills add https://github.com/levnikolaevich/claude-code-skills --skill ln-33-code-modernizer

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Replacing custom code with libraries or newer platform features often introduces hidden regressions, unmaintained dependencies, or bundle bloat. This Skill enforces an evidence-driven modernization workflow that only keeps changes proven to reduce maintenance, workflow friction, or delivered artifact cost.

Core Features & Use Cases

  • Evidence-Based Candidate Evaluation: Compares retain, simplify, platform-native, and external-package options using primary sources for maintenance, security, license, and API fit.
  • Bounded, Reversible Migration: Introduces replacements at one clear boundary with differential testing, data-migration rehearsal, and rollback verification.
  • Measured Keep-or-Discard Verdicts: Compares bundle size, startup, workflow, and defect metrics against baselines and reverts changes that show no net value.
  • Use Case: Replace a hand-rolled date-parsing module with a maintained library, verify behavior with characterization tests, measure the bundle delta, and keep the change only if it proves net value.

Quick Start

Ask the agent to modernize a specific capability, such as replacing the custom CSV parser with a maintained library, and require baseline measurements plus a keep-or-discard verdict.

Frequently Asked Questions about ln-33-code-modernizer

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I safely replace custom code with an external library?▼

Evaluate candidates against maintenance activity, security history, license, and API fit using official documentation and releases. Introduce the replacement at one boundary, run differential tests on old and new implementations, and keep the change only when measured value exceeds migration cost.

How to reduce JavaScript bundle size without breaking functionality?▼

Measure real build composition with parsed and compressed sizes, chunking, and load paths rather than package metadata. Verify tree-shaking and deduplication claims against the actual bundler graph before changing imports, and compare entrypoint critical paths separately.

When should I not modernize working custom code?▼

Do not replace working code merely because an external package exists or for aesthetic reasons. Modernization requires a concrete defect, cost, duplication, or unsupported mechanism with a reproducible benefit to the protected outcome.

How do I verify a dependency is truly unused before removing it?▼

Check dynamic imports, reflection, plugin and config registration, code generation, build scripts, CLIs, and optional runtime paths that static import scans miss. Remove the dependency only after search and runtime wiring checks confirm no remaining consumer.

What happens if a migration shows no measurable improvement?▼

The change is marked DISCARD and reverted completely, restoring the baseline. The final report uses NO_CHANGE when every migration is discarded, and only retained, verified improvements are reported as MODERNIZED.

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