Convert Internal Package to TypeScript
TryGhost/Ghost
Moves a legacy internal Ghost package from JavaScript and CommonJS to TypeScript and ESM in three focused commits that keep git file history intact.
A full pipeline for transforming legacy codebases into modern architectures.
Install Legacy Modernizer
$ npx skills add revfactory/harness-100 --skill legacy-modernizer -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install revfactory/harness-100 legacy-modernizer --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .claude/skills && cp -r skills-src/en/22-legacy-modernizer/.claude/skills/legacy-modernizer .claude/skills/legacy-modernizer && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "legacy-modernizer" agent skill from https://github.com/revfactory/harness-100/tree/main/en/22-legacy-modernizer/.claude/skills/legacy-modernizer into .claude/skills/legacy-modernizer/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "legacy-modernizer", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/revfactory/harness-100/tree/main/en/22-legacy-modernizer/.claude/skills/legacy-modernizerType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add revfactory/harness-100 --skill legacy-modernizer -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install revfactory/harness-100 legacy-modernizer --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .agents/skills && cp -r skills-src/en/22-legacy-modernizer/.claude/skills/legacy-modernizer .agents/skills/legacy-modernizer && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "legacy-modernizer" agent skill from https://github.com/revfactory/harness-100/tree/main/en/22-legacy-modernizer/.claude/skills/legacy-modernizer into .agents/skills/legacy-modernizer/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "legacy-modernizer", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add revfactory/harness-100 --skill legacy-modernizer -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install revfactory/harness-100 legacy-modernizer --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/en/22-legacy-modernizer/.claude/skills/legacy-modernizer .cursor/skills/legacy-modernizer && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "legacy-modernizer" agent skill from https://github.com/revfactory/harness-100/tree/main/en/22-legacy-modernizer/.claude/skills/legacy-modernizer into .cursor/skills/legacy-modernizer/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "legacy-modernizer", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/revfactory/harness-100.git --path en/22-legacy-modernizer/.claude/skills/legacy-modernizer--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add revfactory/harness-100 --skill legacy-modernizer -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install revfactory/harness-100 legacy-modernizer --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/en/22-legacy-modernizer/.claude/skills/legacy-modernizer .gemini/skills/legacy-modernizer && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "legacy-modernizer" agent skill from https://github.com/revfactory/harness-100/tree/main/en/22-legacy-modernizer/.claude/skills/legacy-modernizer into .gemini/skills/legacy-modernizer/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "legacy-modernizer", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install revfactory/harness-100 legacy-modernizerInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add revfactory/harness-100 --skill legacy-modernizer -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .github/skills && cp -r skills-src/en/22-legacy-modernizer/.claude/skills/legacy-modernizer .github/skills/legacy-modernizer && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "legacy-modernizer" agent skill from https://github.com/revfactory/harness-100/tree/main/en/22-legacy-modernizer/.claude/skills/legacy-modernizer into .github/skills/legacy-modernizer/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "legacy-modernizer", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add revfactory/harness-100 --skill legacy-modernizer -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install revfactory/harness-100 legacy-modernizer --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/revfactory/harness-100.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/en/22-legacy-modernizer/.claude/skills/legacy-modernizer .opencode/skills/legacy-modernizer && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "legacy-modernizer" agent skill from https://github.com/revfactory/harness-100/tree/main/en/22-legacy-modernizer/.claude/skills/legacy-modernizer into .opencode/skills/legacy-modernizer/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "legacy-modernizer", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
legacy-modernizer- GitHub stars
- 1.3k
- Token cost
- ~1.9k tokens
- SKILL.md length
- 692 words
- Files
- 1
- Skills in repo
- 464
- Repo updated
- First seen
- Licence
- Apache-2.0
At a glance
A full pipeline for transforming legacy codebases into modern architectures.
- Works in 3 steps: Preparation (Performed directly by… → Team Assembly and Execution → Integration and Final Deliverables
- Requests like modernize legacy code
- SKILL.md covers Execution Mode, Agent Composition, Workflow and Modes by Task Scale, plus 4 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Legacy Modernizer is an agent skill from revfactory/harness-100. A full pipeline for transforming legacy codebases into modern architectures. An agent team collaborates to perform technical debt analysis, refactoring strategy formulation, code migration, and regression testing. Use this skill for requests like 'modernize legacy code', 'create a refactoring strategy', 'code migration', 'technical debt analysis', 'legacy system upgrade', 'framework migration', 'code modernization', 'refactoring plan', and other legacy code modernization tasks. Also supports strategy formulation…
Its SKILL.md is about 1.9k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in Development, covering Legacy modernization and Code migrations. The licence is Apache-2.0.
When your agent uses it
- Requests like modernize legacy code
- Create a refactoring strategy
- Technical debt analysis
- Legacy system upgrade
Example prompts
- “modernize legacy code”
- “create a refactoring strategy”
- “code migration”
- “/legacy-modernizer”
Workflow steps
3 steps, taken from the step headings in SKILL.md.
What it can do on your machine
Read from SKILL.md and the folder at commit 8e8d35c. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Legacy Modernizer loads about 1.9k tokens when it runs. Until then it costs about 182 tokens; SKILL.md has 692 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from revfactory/harness-100 at commit 8e8d35c, republished under its Apache-2.0 licence (© revfactory). 692 words, ~1,870 tokens.
Download SKILL.mdSave it as
.claude/skills/legacy-modernizer/SKILL.md (or your agent's skills folder).- name
- legacy-modernizer
- description
- A full pipeline for transforming legacy codebases into modern architectures. An agent team collaborates to perform technical debt analysis, refactoring strategy formulation, code migration, and regression testing. Use this skill for requests like 'modernize legacy code', 'create a refactoring strategy', 'code migration', 'technical debt analysis', 'legacy system upgrade', 'framework migration', 'code modernization', 'refactoring plan', and other legacy code modernization tasks. Also supports strategy formulation and migration when existing analysis reports are available. Note: actual production deployment, CI/CD pipeline execution, and infrastructure provisioning are outside the scope of this skill.
Legacy Modernizer — Legacy Code Modernization Pipeline
An agent team collaborates to perform analysis -> refactoring strategy -> migration -> verification of legacy code.
Execution Mode
Agent Team — 5 members communicate directly via SendMessage and cross-validate each other.
Agent Composition
| Agent | File | Role | Type |
|---|---|---|---|
| legacy-analyzer | .claude/agents/legacy-analyzer.md | Tech debt identification, dependency mapping, complexity measurement | general-purpose |
| refactoring-strategist | .claude/agents/refactoring-strategist.md | Pattern selection, prioritization, roadmap | general-purpose |
| migration-engineer | .claude/agents/migration-engineer.md | Code transformation, API modernization, framework migration | general-purpose |
| regression-tester | .claude/agents/regression-tester.md | Behavior preservation verification, performance comparison | general-purpose |
| modernization-reviewer | .claude/agents/modernization-reviewer.md | Cross-validation, consistency verification | general-purpose |
Workflow
Phase 1: Preparation (Performed directly by Orchestrator)
- Extract from user input:
- Target Code/System: Codebase or system information to modernize
- Target Architecture (optional): Desired technology stack/patterns to migrate to
- Constraints (optional): Downtime tolerance, budget, timeline
- Existing Documentation (optional): Architecture documents, analysis reports, etc.
- Create
_workspace/directory at the project root - Organize input and save to
_workspace/00_input.md - If existing files are available, copy them to
_workspace/and skip the corresponding Phase - Determine execution mode based on the scope of the request (see "Modes by Task Scale" below)
Phase 2: Team Assembly and Execution
| Order | Task | Assignee | Dependencies | Deliverable |
|---|---|---|---|---|
| 1 | Legacy Analysis | analyzer | None | _workspace/01_legacy_analysis.md |
| 2 | Refactoring Strategy | strategist | Task 1 | _workspace/02_refactoring_strategy.md |
| 3 | Migration Execution Plan | engineer | Tasks 1, 2 | _workspace/03_migration_plan.md |
| 4 | Regression Testing | tester | Tasks 1, 3 | _workspace/04_test_report.md |
| 5 | Final Review | reviewer | Tasks 1-4 | _workspace/05_review_report.md |
Inter-team Communication Flow:
- analyzer completes -> delivers tech debt, hotspots, and dependencies to strategist; delivers tech stack and business logic to engineer; delivers current coverage to tester
- strategist completes -> delivers roadmap and migration mapping to engineer; delivers Phase completion criteria to tester
- engineer completes -> delivers Before/After and verification points to tester
- tester completes -> requests fixes from engineer if regressions are found
- reviewer cross-validates all deliverables. When RED Must Fix items are found, requests fixes from the relevant agent -> rework -> re-verification (up to 2 times)
Phase 3: Integration and Final Deliverables
- Check all files in
_workspace/ - Verify that all RED Must Fix items from the review report have been addressed
- Report the final summary to the user
Modes by Task Scale
| User Request Pattern | Execution Mode | Deployed Agents |
|---|---|---|
| "Modernize the legacy code", "Full refactoring" | Full Pipeline | All 5 agents |
| "Analyze technical debt", "Diagnose code health" | Analysis Mode | analyzer + reviewer |
| "Create a refactoring strategy" (existing analysis available) | Strategy Mode | strategist + reviewer |
| "Migrate this code" (strategy available) | Migration Mode | engineer + tester + reviewer |
| "Verify the migration" | Test Mode | tester + reviewer |
Leveraging Existing Files: If the user provides analysis reports, strategy documents, etc., the corresponding step is skipped.
Show full SKILL.md (278 more words)Show less
Data Transfer Protocol
| Strategy | Method | Purpose |
|---|---|---|
| File-based | _workspace/ directory | Store and share main deliverables |
| Message-based | SendMessage | Real-time delivery of key information, fix requests |
| Task-based | TaskCreate/TaskUpdate | Progress tracking, dependency management |
File naming convention: {order}_{agent}_{deliverable}.{extension}
Error Handling
| Error Type | Strategy |
|---|---|
| Code inaccessible | Inference-based analysis from user-provided information, note "Limited Access" in report |
| No test environment | Substitute with static analysis and code review-based verification |
| Agent failure | Retry once -> if fails, proceed without that deliverable, note omission in review |
| RED found in review | Request fix from relevant agent -> rework -> re-verify (up to 2 times) |
| Circular dependency unresolvable | Insert Anti-Corruption Layer to isolate, then resolve incrementally |
Test Scenarios
Normal Flow
Prompt: "Modernize a legacy web app based on jQuery + Express.js to React + NestJS" Expected Result:
- Analysis: jQuery dependency mapping, Express route structure analysis, technical debt inventory
- Strategy: Strangler Fig pattern, frontend-first migration roadmap
- Migration: jQuery -> React component transformation, Express -> NestJS controller transformation
- Testing: DOM manipulation behavior preservation, API compatibility, performance comparison
- Review: Full consistency verification across all items
Existing File Utilization Flow
Prompt: "Create a refactoring strategy based on this analysis report" + analysis report attached Expected Result:
- Copy existing report to
_workspace/01_legacy_analysis.md - Strategy mode: only strategist + reviewer deployed
- analyzer is skipped
Error Flow
Prompt: "Refactor this code" (only code snippet provided, no full context) Expected Result:
- Start in analysis mode, perform inference-based analysis with limited information
- Note in report: "Partial code-based analysis — full system context unverified"
- Ask user for additional information if needed
Agent Extension Skills
| Skill | Path | Enhanced Agent | Role |
|---|---|---|---|
| strangler-fig-patterns | .claude/skills/strangler-fig-patterns/skill.md | refactoring-strategist, migration-engineer | Detailed implementation of incremental migration patterns (Strangler Fig, Branch by Abstraction, Parallel Run, ACL) |
| dependency-analysis | .claude/skills/dependency-analysis/skill.md | legacy-analyzer, refactoring-strategist | Dependency graph analysis, coupling/cohesion metrics, circular dependency detection and resolution |
© revfactory, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in en/22-legacy-modernizer/.claude/skills/legacy-modernizer of revfactory/harness-100.
Open the folder on GitHubat commit 8e8d35c
Compare with similar skills
Legacy Modernizer next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Legacy Modernizer this skillrevfactory/harness-100 | 1.3k | — | ~1.9k | Automated safety check: Pass | Apache-2.0 | |
| Convert Internal Package to TypeScriptTryGhost/Ghost | 56k | — | ~1.2k | Automated safety check: Pass | MIT | |
| jscpd Code Migration Trackerkucherenko/jscpd | 6.4k | — | ~5k | Automated safety check: Pass | MIT | |
| Rails Upgrade Assistantombulabs/claude-code_rails-upgrade-skill | 389 | — | ~2.7k | Automated safety check: Pass | MIT | |
| Migrate Dotnet8 To Dotnet9dotnet/skills | 5.6k | 2 repos | ~3.9k | Automated safety check: Pass | MIT | |
| AngularJS to Angular Migrationwshobson/agents | 40k | 11 repos | ~1.8k | Automated safety check: Pass | MIT |
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Categories
Questions about Legacy Modernizer
What does Legacy Modernizer do?
A full pipeline for transforming legacy codebases into modern architectures. Legacy Modernizer is an agent skill from revfactory/harness-100. A full pipeline for transforming legacy codebases into modern architectures.
When should I use Legacy Modernizer?
Legacy Modernizer fits situations like: requests like modernize legacy code; create a refactoring strategy; technical debt analysis; legacy system upgrade.
How do I install Legacy Modernizer in Claude Code?
Run `npx skills add revfactory/harness-100 --skill legacy-modernizer -a claude-code`. Or copy the skill folder (en/22-legacy-modernizer/.claude/skills/legacy-modernizer in revfactory/harness-100) into .claude/skills/legacy-modernizer in your project. Claude Code loads it when a task matches its description.
How do I install Legacy Modernizer in Codex?
Run `npx skills add revfactory/harness-100 --skill legacy-modernizer -a codex`. Or copy the skill folder (en/22-legacy-modernizer/.claude/skills/legacy-modernizer in revfactory/harness-100) into .agents/skills/legacy-modernizer in your project. Codex loads it when a task matches its description.
Can I use Legacy Modernizer in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add revfactory/harness-100 --skill legacy-modernizer -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/legacy-modernizer, .gemini/skills/legacy-modernizer, .github/skills/legacy-modernizer and .opencode/skills/legacy-modernizer in your project.
What does Legacy Modernizer need to run?
SKILL.md names no scripts, command-line tools or credentials: Legacy Modernizer is instructions for the agent only.
Does Legacy Modernizer access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Legacy Modernizer safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Legacy Modernizer use?
Legacy Modernizer is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Legacy Modernizer use?
About 1.9k tokens (SKILL.md is roughly 7.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Legacy Modernizer?
Skills that share tags, products or a category with Legacy Modernizer: Convert Internal Package to TypeScript (TryGhost/Ghost, 56k stars), jscpd Code Migration Tracker (kucherenko/jscpd, 6.4k stars), Rails Upgrade Assistant (ombulabs/claude-code_rails-upgrade-skill, 389 stars) and Migrate Dotnet8 To Dotnet9 (dotnet/skills, 5.6k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Legacy Modernizer?
revfactory (a GitHub user) maintains it in revfactory/harness-100, which has 1,295 GitHub stars. The repository holds 464 skills in this directory. The repository was last updated on March 22, 2026.
Source: revfactory/harness-100 on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.