Harness² vs mini-swe-agent

Harness²

Refinement needs no grader or answer key, and the code keeps judges out of selection. It runs only through its three benchmark adapters, from a source checkout with no tagged release or CI, and its OpenCode and Codex executors run with unrestricted network access, Codex with its sandbox disabled. The benchmark gains are the authors' claims.

mini-swe-agent

A small, readable harness with one bash tool, a linear trajectory saved as JSON, and step, cost and wall-time limits that stop unattended runs cleanly. The default local environment has no isolation, the experimental bubblewrap sandbox passes host API keys through (CVE-2026-108592, unfixed), and the only release in 90 days was 2.4.6 on 23 July 2026.

Harness²

1. Don't plan to call Harness² as a service. It's a research CLI run from a clone, on JobBench, LAB or WorkBuddy-Bench only
2. Ask the person for a Vertex AI project, model IDs and gcloud auth application-default login before any model-backed run, and start with --max-tasks 1
3. Run executors behind an egress firewall and block huggingface.co and github.com after setup, as the docs advise, so rubrics can't be fetched
4. Write .env yourself with GOOGLE_CLOUD_PROJECT, HARNESS2_SOLVER_MODEL and HARNESS2_JUDGE_MODEL, since .env.example isn't shipped, and never commit it
5. Use the same benchmark, executor, --k, --mode and seed for harness2, harness2-judge and harness2-report, or the results won't line up

mini-swe-agent

1. Run with -y --exit-immediately for unattended use. Without --exit-immediately it waits for input when the agent finishes
2. Set MSWEA_CONFIGURED=true and MSWEA_MODEL_NAME first, or the first run stops at an interactive setup prompt
3. Read info.exit_status in the -o trajectory file. A run that hits its limits still exits normally
4. For untrusted repositories use -c mini.yaml -c environment.environment_class=docker -c environment.image=<image>. The local and bubblewrap environments both expose host variables
5. Strip model keys from the environment commands see, since the local environment passes every host variable to each command