/harness-bench

name: harness-bench
description: Create (`bench create {repo}`) or verify (`bench verify {suite.json}`) a @metaharness/darwin bench suite, the fixed corpus `harness-evolve --bench` scores variants against. Use when preparing an evolution benchmark. Degrades gracefully without darwin.
argument-hint: "--op create --repo <path> [--out <path>]  |  --op verify --suite <path>"
allowed-tools: Bash
disable-model-invocation: true

Surfaces `metaharness-darwin bench <create|verify>` — the supporting verb for `harness-evolve --bench`. Use when you want evolution scored against a fixed corpus (independent of `npm test`) so champion fitness is comparable across commits or across forks of the same harness.

When to use

• Setting up a new evolution pipeline for a repo whose `npm test` is

flaky, slow, or undersized — scaffold a deterministic bench suite once, then evolve against it repeatedly.

• CI: `bench verify` the checked-in suite on every PR that touches it

(cheap; ~5s).

• Forking a harness to a new domain: copy and edit the suite to retarget

the evaluation without losing comparability to the parent.

Algorithm

Implementation: [`scripts/bench.mjs`](../../scripts/bench.mjs).

`--op create`

1. Resolve `--repo` path; reject if missing. 2. Shell to `metaharness-darwin bench create <repo> [--out <suite.json>]`. 3. Default output path: `<repo>/.metaharness/bench/suite.json` (chosen by upstream). 4. Suite shape (per upstream): array of `{ input, expectedOutput, weight }` tasks derived from existing test cases.

`--op verify`

1. Resolve `--suite` path; reject if missing. 2. Shell to `metaharness-darwin bench verify <suite.json>`. 3. Exit 1 if any task malformed (upstream's signal).

Output shape

{
  "success": true,
  "data": {
    "op": "verify",
    "taskCount": 42,
    "wellFormed": true,
    "durationMs": 870
  }
}

Exit codes

| Code | Meaning | |---|---| | 0 | OK (or degraded — Darwin absent) | | 1 | `--op verify` and suite malformed | | 2 | Config error or upstream invocation failure |

Graceful degradation

When `@metaharness/darwin` is absent, emits the standard `{degraded: true, reason: 'metaharness-darwin-not-available'}` payload and exits 0.