Autonomous Build

/mk:harness builds entire products from a description. It's for "build me a kanban app" scope — not single features (use /mk:cook for those). It runs a planner → contract → generator ⇄ evaluator loop with minimal handholding.

Quick start

/mk:harness build a kanban board with drag-and-drop

MeowKit detects your model tier, selects the right scaffolding density, and drives the full build. You approve at Gate 1 (plan) and Gate 2 (review). The evaluator grades the running app against rubrics. If it fails, the harness loops back to the generator — up to 3 rounds.

When to use

Situation	Use
Green-field product from scratch	/mk:harness
Single feature on existing codebase	/mk:cook
Bug fix	/mk:fix

Scaffolding density

The harness adjusts automatically based on your model tier:

Model	Density	What runs
Haiku	MINIMAL	Short-circuits to /mk:cook
Sonnet	FULL	Sprint contract + 1-3 iteration rounds
Opus 4.5	FULL	Contract + full pipeline
Opus 4.6+	LEAN	Single-session, contract optional, 0-1 rounds

Override with --tier or MEOWKIT_HARNESS_MODE:

/mk:harness build a todo app --tier full     # Force FULL density
/mk:harness build a retro game maker --tier lean  # Force LEAN

Budget control

/mk:harness build a markdown editor --budget 25 --max-iter 2

• Default budget: $100 hard cap (warns at $30)
• --budget N overrides the cap
• --max-iter N limits generator/evaluator rounds (default 3)

What gets produced

Artifact	Location
Product plan	tasks/plans/{slug}/plan.md
Sprint contract	tasks/contracts/{date}-{slug}-sprint-N.md
Evaluator verdict	tasks/reviews/{slug}-evalverdict.md
Full audit trail	tasks/harness-runs/YYMMDD-{slug}/run.md

Resuming after interruption

/mk:harness --resume 260501-1450-build-kanban

Picks up at the last completed step. Run reports are append-only — no work is lost.

Exit statuses

Status	Meaning
PASS	Evaluator graded the build as passing
WARN	Minor issues found, build is acceptable
FAIL	Evaluator rejected the build after 3 iterations
ESCALATED	Human intervention required
TIMED_OUT	Budget cap reached

Don't use /mk:harness for

• Single features or bug fixes — use /mk:cook or /mk:fix
• Doc updates or code reviews — use targeted skills
• Analysis or explanation — harness is for building, not research

Next steps

• Build a feature — the single-feature pipeline
• Adaptive density — the dead-weight thesis in detail
• Trace & benchmark — measuring harness performance