Legacy

Q: What is a Claude Code skill and how does the Legacy skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Legacy is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Engineering · Sub-category: performance · Last updated: 2026-06-13

lang:rust

Scans Rust code for edition-specific patterns and deprecated APIs, then migrates to a target edition (2015 → 2018 → 2021 → 2024) or updates breaking crate API changes (tokio 0.x → 1.x, diesel 1.x → 2.x, failure → anyhow/thiserror, futures 0.1 → async/await). Detects extern crate declarations, old module syntax (mod.rs), try!() macro, pre-NLL borrow patterns, and deprecated std APIs. Use when the user says "migrate to Rust 2021", "upgrade edition", "this is old Rust", "update tokio", "replace failure crate", or when rustc produces edition warnings. Do NOT use for dependency management (Cargo), performance optimization (web-optimize), or general refactoring unrelated to Rust edition/API compatibility.

From the source SKILL.md

Detects edition-specific patterns and deprecated APIs in the Rust codebase, then produces a migration plan and applies changes file by file — migrating to a newer edition or updating breaking crate API changes.

What this skill does

Legacy is a community-contributed Claude Code skill in the performance sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/legacy/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when the user says "migrate to Rust 2021", "upgrade edition", "this is old Rust", "update tokio", "replace failure crate", or when rustc produces edition warnings. Do NOT use for dependency management (Cargo), performance optimization (web-optimize), or general refactoring unrelated to Rust edition/API compatibility.

Who uses this skill

The Legacy Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 121,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/legacy
curl -L https://claudskills.com/skills/legacy/SKILL.md \
  -o ~/.claude/skills/legacy/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/legacy/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/legacy/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\legacy\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Legacy Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/legacy/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the Legacy skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the Legacy skill?

Use Legacy when your Claude Code task falls under the Engineering category — specifically in the performance area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Legacy" or describe the task and let Claude pick). Browse related skills at /category/engineering/.

What is a Claude Code skill and how does the Legacy skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Legacy is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/RebelliousSmile/my-claude-marketplace/blob/b899e0eb8a0a1a841bbf0261d7cd476ca7d01b1b/plugins/sc-rust/skills/legacy/SKILL.md
License: MIT
Author: RebelliousSmile

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

RebelliousSmile. (2026). Legacy [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/legacy/

BibTeX

@misc{legacy-2026,
  author    = {RebelliousSmile},
  title     = {Legacy [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/legacy/}
}

Embed this skill

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Badge

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