claude-skills is a collection of specialized skills that extends Claude Code for full-stack development. Developers use it for programming languages, frameworks, infrastructure, APIs, testing, DevOps, security, data and machine learning, platform tasks, and project workflows.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add Jeffallan/claude-skills --skill legacy-modernizergit clone --depth 1 https://github.com/Jeffallan/claude-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/jeffallan/claude-skills/legacy-modernizer)<a href="https://agentmods.dev/skills/jeffallan/claude-skills/legacy-modernizer"><img src="https://agentmods.dev/badge/skills/jeffallan/claude-skills/legacy-modernizer/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/jeffallan/claude-skills/legacy-modernizer"><img src="https://agentmods.dev/badge/skills/jeffallan/claude-skills/legacy-modernizer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00069 | $0.01269 |
| Opus 5 | $0.00034 | $0.00634 |
| Sonnet 5 | $0.00014 | $0.00254 |
| Haiku 4.5 | $0.00007 | $0.00127 |
Grade A, and why
legacy-modernizer scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
return self._new.fetch(order_id) Copies of this mod
1 near-identical copy found in the catalogue:
- legacy-modernizer — 94% identical, 2 lines differ
How it starts
The opening of the file, as written. The whole thing — 140 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Legacy Modernizer
Core Workflow
-
Assess system — Analyze codebase, dependencies, risks, and business constraints. Produce a dependency map and risk register before proceeding.
- Validation checkpoint: Confirm all external integrations and data contracts are documented before moving to step 2.
-
Plan migration — Design an incremental roadmap with explicit rollback strategies per phase. Reference
references/system-assessment.mdfor code analysis templates.- Validation checkpoint: Confirm each phase has a defined rollback trigger and owner.
-
Build safety net — Create characterization tests and monitoring before touching production code. Target 80%+ coverage of existing behavior.
- Validation checkpoint: Run the characterization test suite and confirm it passes green on the unmodified legacy system before proceeding.
-
Migrate incrementally — Apply strangler fig pattern with feature flags. Route traffic via a facade; shift load gradually.
- Validation checkpoint: Verify error rates and latency metrics remain within baseline thresholds after each traffic increment (e.g., 5% → 25% → 50% → 100%).
-
Validate & iterate — Run full test suite, review monitoring dashboards, and confirm business behavior is preserved before retiring legacy code.
- Validation checkpoint: New code must be proven stable at 100% traffic for at least one release cycle before legacy path is removed.
Reference Guide
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Strangler Fig | references/strangler-fig-pattern.md |
Incremental replacement, facade layer, routing |
| Refactoring | references/refactoring-patterns.md |
Extract service, branch by abstraction, adapters |
| Migration | references/migration-strategies.md |
Database, UI, API, framework migrations |
| Testing | references/legacy-testing.md |
Characterization tests, golden master, approval |
| Assessment | references/system-assessment.md |
Code analysis, dependency mapping, risk evaluation |
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 12d ago First seen · 140 lines · 69 tokens per session scan A 0d2258af837c
legacy-modernizer is a skill published in the GitHub repository Jeffallan/claude-skills (11,426 stars, last pushed 1mo ago), licensed MIT. It adds 69 tokens to every session and 1,269 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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