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legacy-migration

Migrate legacy features to the kernel with parity verification and atomic removal.

7|Updated Nov 21, 2015
Search Tags:#git#refactoring#software development#feature parity#code migration#legacy code#kernel
One-click install
npx skills add https://github.com/ryanbreen/breenix --skill legacy-migration
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: legacy-migration
Source: https://github.com/ryanbreen/breenix/tree/main/breenix-legacy-migration
Command: npx skills add https://github.com/ryanbreen/breenix --skill legacy-migration

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Migrating features from a legacy codebase to a new implementation can be risky, leading to regressions or accumulating dead code. This Skill provides a systematic workflow for safely porting features, verifying parity, and atomically removing legacy code, ensuring a clean and modern kernel.

Core Features & Use Cases

  • Systematic Feature Porting: Follow a structured process to move features from src.legacy/ to the new kernel/ implementation.
  • Parity Verification: Rigorously confirm that the new implementation matches the behavior of the legacy code.
  • Atomic Code Removal: Safely remove old code in the same commit as feature completion, preventing dead code accumulation.
  • Use Case: You've reimplemented the memory management subsystem. Use this Skill to verify its functional equivalence with the legacy version, update the FEATURE_COMPARISON.md documentation, and then confidently remove the old src.legacy/memory code in a single, atomic commit.

Quick Start

Identify features for migration

cat docs/planning/legacy-migration/FEATURE_COMPARISON.md | grep "❌"

Remove legacy files and update docs in the SAME commit

git rm src.legacy/path/to/feature.rs git add docs/planning/legacy-migration/FEATURE_COMPARISON.md git commit -m "Complete Feature X implementation and remove legacy"

Frequently Asked Questions about legacy-migration

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

FAQPage Schema
How do I safely migrate features from legacy code to a new kernel implementation?▼

Feature migration involves a systematic workflow: identify features in src.legacy/, reimplement them in the kernel using modern patterns, verify functional parity with the legacy version, update documentation like FEATURE_COMPARISON.md, and remove old code in an atomic commit. This ensures no regressions and prevents dead code accumulation.

How do I verify that my new kernel implementation matches the legacy code's behavior?▼

Parity verification confirms the new implementation produces equivalent results to legacy code. Review legacy patterns, trace execution paths, add tests covering both implementations, and document comparisons in FEATURE_COMPARISON.md before atomically removing the old code.

What's the best way to remove legacy code without introducing regressions?▼

Remove legacy code in the same commit as feature completion, after parity verification is confirmed. Use atomic commits via git rm and git add to ensure the removal is tied to tested, working kernel code, preventing broken intermediate states.

Can I migrate individual subsystems like memory management from legacy to kernel?▼

Yes. The workflow supports subsystem-level migration. Reimplement the subsystem in kernel/, verify all memory management functions match legacy behavior, update FEATURE_COMPARISON.md to reflect completion, then remove src.legacy/memory in a single atomic commit.

What should I document during a legacy code migration?▼

Update FEATURE_COMPARISON.md to track migration status for each feature, document API compatibility decisions for public interfaces, add tests and implementation notes in kernel code, and include reference documentation so future developers understand why legacy code was removed.

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