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Agent skill

TDD Refactor Guard

by gustavscirulis in gustavscirulis/snapgrid

Pre-refactor safety checklist. An agent skill from gustavscirulis/snapgrid.

Custom licenceAuto-check: notesTesting & QA

Install TDD Refactor Guard

skills CLI
$ npx skills add gustavscirulis/snapgrid --skill tdd-refactor-guard -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install gustavscirulis/snapgrid tdd-refactor-guard --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/gustavscirulis/snapgrid.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/skills/testing/tdd-refactor-guard .claude/skills/tdd-refactor-guard && rm -rf skills-src

Use ~/.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/

Facts

Skill name
tdd-refactor-guard
GitHub stars
116
Used in
1 other repo
Token cost
~1.8k tokens
SKILL.md length
392 words
Files
1
Skills in repo
118
Repo updated
First seen
Licence
Custom licence

At a glance

Pre-refactor safety checklist. An agent skill from gustavscirulis/snapgrid.

  • Works in 6 steps: Identify Scope → Check Existing Test Coverage → Evaluate Test Quality → …
  • Tasks that involve Refactoring
  • SKILL.md covers When This Skill Activates, Why This Guard Exists, Process and Refactoring Safeguards, plus 2 more sections
  • Calls xcodebuild

What it does

TDD Refactor Guard is an agent skill from gustavscirulis/snapgrid. Pre-refactor safety checklist. Verifies test coverage exists before AI modifies existing code. Use before asking AI to refactor anything.

Its SKILL.md is about 1.8k 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 Testing & QA, covering Refactoring, Test-driven development and Test coverage. The repository describes itself as: SnapGrid is an open-source Mac app for collecting, organizing, and analyzing UI screenshots. It uses AI to automatically detect UI components and patterns, making it a powerful…

When your agent uses it

  • Tasks that involve Refactoring
  • Tasks that involve Test-driven development
  • Tasks that involve Test coverage

Example prompts

  • “/tdd-refactor-guard”

Requirements

  • Pre-approved tools (allowed-tools): Read, Write, Edit, Glob, Grep, Bash, AskUserQuestion

Workflow steps

6 steps, taken from the step headings in SKILL.md.

  1. Identify Scope
  2. Check Existing Test Coverage
  3. Evaluate Test Quality
  4. Generate Missing Tests
  5. Green Light / Red Light
  6. Post-Refactor Verification

What it can do on your machine

Read from SKILL.md and the folder at commit eb7eaf4. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read
    • Write
    • Edit
    • Glob
    • Grep
    • Bash
    • AskUserQuestion

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • xcodebuild

    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

TDD Refactor Guard loads about 1.8k tokens when it runs. Until then it costs about 39 tokens; SKILL.md has 392 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~39
When it runs · the whole SKILL.md, loaded when a task matches
~1.8k

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: notes

The automated check noted patterns worth knowing about, such as sudo or a known installer.

  • NotePre-approves every shell command (allowed-tools: Bash)SKILL.md
    allowed-tools: Read, Write, Edit, Glob, Grep, Bash, AskUserQuestion

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

Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 392 words (~1,765 tokens).

“A safety gate that runs before any AI-assisted refactoring. Ensures tests exist to catch regressions. If coverage is insufficient, generates characterization tests first.”

— opening of SKILL.md by gustavscirulis, Custom licence
name
tdd-refactor-guard
allowed-tools
Read, Write, Edit, Glob, Grep, Bash, AskUserQuestion

Read the full SKILL.md on GitHub

Files

Just SKILL.md in .claude/skills/skills/testing/tdd-refactor-guard of gustavscirulis/snapgrid.

Open the folder on GitHubat commit eb7eaf4

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in gustavscirulis/snapgrid, which our catalogue first saw on October 7, 2026.

Compare with similar skills

TDD Refactor Guard 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.

TDD Refactor Guard compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
TDD Refactor Guard this skillgustavscirulis/snapgrid1161 repos~1.8kAutomated safety check: NotesCustom licence
Test Guidelinesgetsentry/sentry-dart873—~3.1kAutomated safety check: PassMIT
Characterisation Testscitypaul/.dotfiles740—~3.6kAutomated safety check: PassCustom licence
Test Driven Developmentaiskillstore/marketplace433—~1.9kAutomated safety check: PassNone
Test Coveragescott-fryxell/brayness125—~1.6kAutomated safety check: PassMIT
TDD ImplementFastLED/FastLED7.5k—~1kAutomated safety check: PassMIT

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Categories

Questions about TDD Refactor Guard

What does TDD Refactor Guard do?

Pre-refactor safety checklist. An agent skill from gustavscirulis/snapgrid. TDD Refactor Guard is an agent skill from gustavscirulis/snapgrid. Pre-refactor safety checklist.

When should I use TDD Refactor Guard?

TDD Refactor Guard fits situations like: tasks that involve Refactoring; tasks that involve Test-driven development; tasks that involve Test coverage.

How do I install TDD Refactor Guard in Claude Code?

Run `npx skills add gustavscirulis/snapgrid --skill tdd-refactor-guard -a claude-code`. Or copy the skill folder (.claude/skills/skills/testing/tdd-refactor-guard in gustavscirulis/snapgrid) into .claude/skills/tdd-refactor-guard in your project. Claude Code loads it when a task matches its description.

How do I install TDD Refactor Guard in Codex?

Run `npx skills add gustavscirulis/snapgrid --skill tdd-refactor-guard -a codex`. Or copy the skill folder (.claude/skills/skills/testing/tdd-refactor-guard in gustavscirulis/snapgrid) into .agents/skills/tdd-refactor-guard in your project. Codex loads it when a task matches its description.

Can I use TDD Refactor Guard 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 gustavscirulis/snapgrid --skill tdd-refactor-guard -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/tdd-refactor-guard, .gemini/skills/tdd-refactor-guard, .github/skills/tdd-refactor-guard and .opencode/skills/tdd-refactor-guard in your project.

What does TDD Refactor Guard need to run?

Going by SKILL.md and its folder, TDD Refactor Guard needs the command-line tools its instructions call (xcodebuild). Its frontmatter pre-approves these tools: Read, Write, Edit, Glob, Grep, Bash, AskUserQuestion.

Does TDD Refactor Guard 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 TDD Refactor Guard safe to install?

Our automated static check of SKILL.md found notes only (pre-approves every shell command (allowed-tools: bash)), nothing it rates as a warning. It is not a guarantee. Review the folder before installing.

What licence does TDD Refactor Guard use?

TDD Refactor Guard has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.

How many tokens does TDD Refactor Guard use?

About 1.8k tokens (SKILL.md is roughly 7.1k 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 TDD Refactor Guard?

Skills that share tags, products or a category with TDD Refactor Guard: Test Guidelines (getsentry/sentry-dart, 873 stars), Characterisation Tests (citypaul/.dotfiles, 740 stars), Test Driven Development (aiskillstore/marketplace, 433 stars) and Test Coverage (scott-fryxell/brayness, 125 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains TDD Refactor Guard?

gustavscirulis (a GitHub user) maintains it in gustavscirulis/snapgrid, which has 116 GitHub stars. The repository holds 118 skills in this directory. The repository was last updated on April 30, 2026.

Source: gustavscirulis/snapgrid on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.