Crosscheck

Crosscheck is the 2x-maintained, open-source verification gate for completed work. Its deterministic runtime binds evidence to an exact target and returns PASS, FAIL, or BLOCKED. Only PASS clears that target. A later change or expired result requires fresh verification. PASS grants no merge, closure, deployment, or account-change authority.

Release candidate: 0.3.0-rc.1. The runtime, schemas, approved $crosscheck skill and four references are packaged for review. Fresh independent QA and owner release verification remain required. The existing qa-agent plugin and $independent-verification skill remain unchanged and usable; they do not automatically enforce the new runtime.

Install the runtime

Requires Python 3.11 or later. From this repository checkout:

./scripts/install-runtime.sh .venv-crosscheck
.venv-crosscheck/bin/crosscheck --help

The installer creates a new isolated environment and refuses to overwrite an existing one. This repository is the canonical source: 2xgrowthagency/crosscheck, renamed from 2xgrowthagency/independent-qa-agent. The Python distribution is crosscheck-verifier; no package registry release has been published. Install the reviewed checkout, not an assumed registry package.

Codex candidate installation

From a reviewed candidate checkout, register that local repository:

codex plugin marketplace add /path/to/reviewed-crosscheck-checkout
codex plugin add crosscheck@independent-qa-agent

Start a fresh task and invoke $crosscheck. This installs the instructions; install the runtime separately using the command above. The marketplace retains its machine name independent-qa-agent to preserve installed references; its visible name is Crosscheck. The main-branch marketplace will gain the canonical plugin only after the owner releases this candidate.

The legacy installation remains qa-agent@independent-qa-agent, invoking $independent-verification. Existing users can keep it alongside Crosscheck.

Claude Code installation

./scripts/install-claude-skill.sh /path/to/target-project crosscheck

This copies the approved skill and four references into .claude/skills/crosscheck/. Start a fresh Claude Code session in that project and invoke /crosscheck. Runtime installation is separate. The installer refuses to overwrite existing instructions or copy an incomplete managed package.

Omitting crosscheck retains the legacy default: the unchanged .claude/skills/independent-verification/ package, invoked with /independent-verification. Actual harness discovery and invocation are separate checks from Python entry points and filesystem copying; see the isolated harness checks.

Runtime usage

A trusted fresh verifier collects observations and a current target readback. The runtime checks those inputs; it does not launch an agent, execute producer commands, enforce an operating-system sandbox, or prove that an attestation is true. The harness must provide execution separation and a read-only target.

crosscheck evaluate \
  --manifest /path/to/evidence/evidence-manifest.json \
  --evidence-root /path/to/evidence \
  --current-target /path/to/current-target.json \
  --target-root /path/to/read-only-product \
  --output /path/to/new-private-report-directory

The output contains qa-report.md, evidence-manifest.json, and crosscheck-receipt.json. Keep the original artifact bundle alongside the reports; manifest artifact paths resolve against --evidence-root. A missing receipt means an incomplete run. Exit codes are 0 for PASS, 1 for FAIL, and 2 for BLOCKED or an invalid/unavailable contract. A malformed contract cannot issue a valid receipt.

Before consuming a stored result, run crosscheck verify-receipt with the same inputs and --receipt /path/to/crosscheck-receipt.json, omitting --output. It reads qa-report.md beside the receipt, or the exact file specified by --report. Missing or changed report bytes fail closed. Validated PASS, FAIL and BLOCKED receipts retain exit codes 0, 1 and 2, respectively; invalid or stale inputs return BLOCKED with exit 2. Receipt schema 1.1 requires report hashes and criterion totals; pre-release 1.0 receipts cannot clear this revised gate. The current-target file must be freshly read by the trusted harness each time. Never use a comment, old target snapshot or gate_cleared boolean as approval.

The unreleased final-boss CLI remains an alias and still writes final-boss-receipt.json; Python final_boss imports share the Crosscheck runtime. Stored Final Boss report/receipt pairs remain readable only when their exact original bytes, bound target and freshness still validate. New reports and comments use Crosscheck; exact legacy comment markers are reconciled in place. See the migration matrix for installed legacy skill identities, which remain unchanged.

Supported targets and evidence

The profile policy defines inputs, checks, evidence, failure modes, stop conditions and PASS meaning for code/PR, UI, interactive workflows, documents, data, operations, decisions and QA processes. Multiple criteria can use different profiles in one bound target.

See the contract reference, synthetic screenshot and interaction bundle, PASS/FAIL/BLOCKED comment examples, integration interfaces, and migration matrix.

Development

python3 -m venv .venv
.venv/bin/pip install -r requirements.txt
.venv/bin/python tests/validate.py
.venv/bin/python -m unittest discover -s tests -v
.venv/bin/python tests/install_smoke.py
git diff --check

CI checks Python 3.11, 3.12 and 3.14. Optional screenshot recapture uses Playwright 1.58.0 and scripts/capture-demo.py; normal tests replay fixed synthetic bytes and never launch a browser, access credentials, or call a model. See contribution and release requirements.

MIT license. Migration behavior derives from John Chan’s public v0.2.1 implementation; private company instructions are not included.