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harness-writing

95 / 100 · Low risk

Fine to try. Some of what it can do is expected: a coding skill usually runs build and test commands.

By trailofbits/skills (GitHub) · coding · 8,130 stars · scanned at commit e4dd0bb

Designs and improves fuzzing harnesses for C/C++ and Rust. Covers mapping raw bytes onto a target API, generating structured inputs, avoiding non-determinism and false crashes, and deciding what to fuzz together. Use when writing a first LLVMFuzzerTestOneInput or fuzz_target! harness, when a campaign finds nothing or reports crashes that will not reproduce, or when the target API needs structured rather than raw input.

Works with any agent that supports SKILL.md skills.

What this skill can do

Install

Paste this into your terminal. It downloads exactly the version we scanned, not whatever is newest.

if [ -e ~/.agents/skills/'harness-writing' ] || [ -L ~/.agents/skills/'harness-writing' ]; then echo 'A skill folder named harness-writing already exists — not replacing it' >&2; false; else d=$(mktemp -d) && git clone --quiet --filter=blob:none --no-checkout 'https://github.com/trailofbits/skills' "$d" && git -C "$d" checkout --quiet 'e4dd0bb5b15535f7c5a0834187dffba6ac37e4ff' -- 'plugins/testing-handbook-skills/skills/harness-writing' && mkdir -p ~/.agents/skills && cp -R "$d"/'plugins/testing-handbook-skills/skills/harness-writing' ~/.agents/skills/'harness-writing' && rm -rf "$d"; fi

Codex reads ~/.agents/skills directly. For Claude Code, Cursor, Copilot, Gemini CLI, Antigravity or OpenCode, also link it. For Claude Code: ln -s ~/.agents/skills/'harness-writing' ~/.claude/skills/'harness-writing' (other agents: ~/.cursor/skills, ~/.copilot/skills, ~/.gemini/skills, ~/.gemini/config/skills, ~/.config/opencode/skills). Or install through the finder skill, which does both.

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