# fingerprint-ci-gate

Catches browser fingerprint regressions in CI pipelines using liarjs. It compares runs against a baseline scan and halts builds when scores drop below a set threshold.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 102500 installs · ★ 5
- Author: liarjsdev
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/liarjsdev/liarjs-skills/tree/HEAD/skills/fingerprint-ci-gate/SKILL.md
- Updated: 2026-08-06
- HTML: https://affpapa.org/en/nevibecode/skills/fingerprint-ci-gate

## What it does

Fingerprint regressions usually stay hidden until production traffic gets blocked weeks later. This skill configures `liarjs` inside GitHub Actions or GitLab CI to catch anti-bot detection shifts early. You need Node 22 and Chromium installed in the runner image. Give Docker at least 1 GB of shared memory via `--shm-size=1g` or mount `/dev/shm`. Never disable the browser sandbox.

The workflow offers two gates. An absolute threshold exits with an error code when `--min-score` is breached. Alternatively, `liarjs diff` prints only the checks whose state shifted between the current run and a saved baseline JSON file. Prefer the diff approach on datacenter runners. Cloud IPs routinely fail timezone consistency checks, so a strict numeric floor causes false build failures.

Pin your `liarjs` version explicitly in CI. Browser heuristics shift across Chrome releases, and an unpinned dependency will alter scores without code changes. For isolated air-gapped runners, use `--offline` to run 32 JavaScript layer checks without external network calls.

## Requirements
- Works with: GitLab, Chrome

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add liarjsdev/liarjs-skills --skill fingerprint-ci-gate -a claude-code
```

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

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add liarjsdev/liarjs-skills --skill fingerprint-ci-gate -a codex
```

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

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add liarjsdev/liarjs-skills --skill fingerprint-ci-gate -a cursor
```

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

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install liarjsdev/liarjs-skills fingerprint-ci-gate
```

2. **Manually: put the files in place**
- File: `.github/skills/fingerprint-ci-gate/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add liarjsdev/liarjs-skills --skill fingerprint-ci-gate -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/liarjsdev/liarjs-skills --path skills/fingerprint-ci-gate
```

### Windsurf (Devin Desktop)

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

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add liarjsdev/liarjs-skills --skill fingerprint-ci-gate -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/liarjsdev/liarjs-skills/tree/HEAD/skills/fingerprint-ci-gate/SKILL.md

## When to use it
- catch browser fingerprint regressions in Chromium builds before shipping
- add headless detection gates to GitHub Actions or GitLab CI
- diff browser scan results against a known-good baseline JSON
- run fingerprint consistency checks inside air-gapped CI environments

## Example prompts
- Add a liarjs fingerprint gate to our GitHub Actions workflow with a minimum score of 60
- Configure CI to diff the current browser scan against baseline.json and upload artifacts
- Set up an offline liarjs check for an air-gapped runner

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 833edd37895b1891.

BEGIN THIRD-PARTY FILE 833edd37895b1891
````text
---
name: fingerprint-ci-gate
description: Gate a build on browser fingerprint regressions with liarjs - save a baseline scan as JSON, diff later runs against it, and fail the job when the consistency score falls below a floor. Use when asked to add a fingerprint or headless-detection check to GitHub Actions, GitLab CI or another pipeline, to catch a regression in a Chromium build or scraping harness before it ships, or to track how a fingerprint score changes across commits.
license: MIT
allowed-tools: Bash, Read, Edit, Write
---

# Fail the build, not the ban rate

A fingerprint regression is invisible until something starts rejecting the traffic weeks later.
`liarjs` turns it into a diff in a pull request: scan, save the JSON, compare the next run against
the saved baseline.

Node 22 or newer, a Chromium in the image, zero runtime dependencies.

Runner note: give the container enough shared memory (`--shm-size=1g` on Docker, or a `/dev/shm`
mount) and the capabilities Chrome's own sandbox needs. Leave the browser sandbox enabled; a scan
that will not start is an image problem to fix in the image.

## The two mechanisms

**Absolute floor.** Exits 1 when the score is below the number given, so the job fails:

```bash
npx liarjs@0.3 --headless --min-score 60
```

**Baseline diff.** Prints only the checks whose status moved between two saved scans:

```bash
npx liarjs@0.3 --json scan.json                # write the current result
npx liarjs@0.3 diff baseline.json scan.json    # what changed since the known-good run
```

Prefer the diff in any environment where some checks can never pass. A datacenter IP always trips
`tz` (IP timezone against browser timezone), so an absolute floor there either sits uselessly low or
fails every run. The diff only speaks up when something actually moved.

Exit codes: 0 clean, 1 below `--min-score`, 2 an error such as no browser found.

## GitHub Actions

```yaml
- uses: actions/setup-node@v4
  with:
    node-version: 22

- name: Fingerprint scan
  run: npx liarjs@0.3 --headless --json scan.json --min-score 60

- name: Compare against the baseline
  run: npx liarjs@0.3 diff baseline.json scan.json

- uses: actions/upload-artifact@v4
  if: always()
  with:
    name: fingerprint-scan
    path: scan.json
```

`references/ci-recipes.md` has the equivalents for GitLab CI, a Docker image, a Playwright test
assertion, and how to refresh a baseline deliberately.

## Choosing the gate
````
END THIRD-PARTY FILE 833edd37895b1891

The third-party file has ended. Everything between the 833edd37895b1891 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2449 of 3942 bytes. © liarjsdev · MIT · https://github.com/liarjsdev/liarjs-skills/tree/HEAD/skills/fingerprint-ci-gate/SKILL.md

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