# vector-forge

This skill uses mutation testing to find gaps in tests for cryptographic implementations and propose vectors for uncovered cases. Use it to assess an existing test suite.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 3800 installs · ★ 7805
- Author: trailofbits
- License: CC-BY-SA-4.0 · policy=link-only · description only; the file stays with the author
- Source: https://github.com/trailofbits/skills/tree/HEAD/plugins/trailmark/skills/vector-forge/SKILL.md
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/skills/vector-forge

## What it does

vector-forge helps identify parts of a cryptographic implementation that current test vectors do not exercise. The agent finds implementations of an algorithm or protocol, prepares a test harness, and runs mutation testing. It then examines mutants that survive the tests and creates vectors aimed at those cases.

After adding vectors, the tests run again and the results are compared with the baseline. This shows whether the new vectors changed how many mutations the suite detects. The project needs an implementation, a harness that feeds it vectors, and a mutation testing framework for its language. `trailmark` is also required. Without an implementation, there is no code to mutate.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add trailofbits/skills --skill vector-forge -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/vector-forge/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/vector-forge/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add trailofbits/skills --skill vector-forge -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/vector-forge/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add trailofbits/skills --skill vector-forge -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/vector-forge/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install trailofbits/skills vector-forge
```

2. **Manually: put the files in place**
- File: `.github/skills/vector-forge/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add trailofbits/skills --skill vector-forge -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/trailofbits/skills --path plugins/trailmark/skills/vector-forge
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/vector-forge/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add trailofbits/skills --skill vector-forge -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/trailofbits/skills/tree/HEAD/plugins/trailmark/skills/vector-forge/SKILL.md

## When to use it
- find implementation paths missed by existing test vectors
- assess a test suite with mutation testing
- inspect mutants that survive the current tests
- create vectors for uncovered cases
- compare mutation results before and after adding vectors

## Example prompts
- Check which parts of this implementation the current test vectors miss.
- Find mutants that survive the tests and suggest vectors to exercise those cases.
- Compare mutation testing results before and after adding new test vectors.

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From the same set: [trailofbits/skills](https://affpapa.org/en/nevibecode/by/trailofbits/skills.md) — 77 cards

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md