Harness — Multi-Agent Orchestration

Orchestrate complex tasks through Planning → Generation ��� Evaluation → Retro. Fresh sub-agents per checkpoint prevent drift. Retro accumulates learning across tasks.

Recommended Workflow

Session 1 (Claude Code) → Plan + Spec → Spec review with cross-model evaluator
    ↓ spec approved
Session 2 (Codex)       → Execute checkpoints → Evaluate → E2E → Full-verify → PR → Retro
    ↕ Gemini CLI as review-loop peer (cross-model quality gate)

• Session 1: Claude Code for interactive discovery — brainstorming, multi-turn Q&A, spec refinement with Spec Evaluator.
• Session 2: Codex for autonomous execution — implementation, evaluation, PR creation, retro. A second peer CLI (Codex or Gemini, matching the review-loop skill's supported peers) serves as cross-model reviewer via review-loop.
• Both hosts support both phases. The above is the recommended flow, not a hard constraint.

Prerequisites

1. superpowers plugin installed (Claude Code): Generator preloads TDD, verification, debugging skills
2. Reviewer role definitions: harness-spec-evaluator.md, harness-generator.md, harness-evaluator.md, harness-retro.md — ship with this plugin at plugins/harness-engineering-skills/agents/; user overrides may live at ~/.claude/agents/harness-*.md
3. python3 on PATH (engine JSON operations)
4. git repository initialized
5. For Codex-hosted execution: claude CLI on PATH for sub-agent dispatch (reviewer roles). The review-loop peer is a separate choice (codex or gemini) — see the review-loop skill.

Verify (Claude Code): claude plugin list | grep superpowers Verify (review roles): ls ~/.claude/plugins/**/plugins/harness-engineering-skills/agents/harness-*.md 2>/dev/null || ls plugins/harness-engineering-skills/agents/harness-*.md (plugin-bundled) and ls ~/.claude/agents/harness-*.md 2>/dev/null (optional user override) Verify (Codex): codex --version && claude --version

Engine Script

All deterministic state management is handled by harness-engine.sh. To locate it:

ENGINE="$(find ~/.claude/plugins/cache -path "*/harness/scripts/harness-engine.sh" -type f 2>/dev/null | head -1)"

If not found, try find ~/.claude/skills -path "*/harness/scripts/harness-engine.sh" or find ~/.codex/skills -path "*/harness/scripts/harness-engine.sh" as fallback. In a checked-out repo, plugins/harness-engineering-skills/skills/harness/scripts/harness-engine.sh is also valid.

Delegate ALL file-system and git bookkeeping to the engine.

Configuration

Setting	Default	Options
max_spec_rounds	3	1–5
max_eval_rounds	3	1–5
cross_model_review	true	true → triggers review-loop after E2E, before PR
cross_model_peer	codex	codex, gemini — matches the peers supported by the bundled review-loop skill
auto_retro	true	false to skip retro
claude_md_path	auto	Path to CLAUDE.md. auto detects
max_verify_rounds	3	1–5, max iterations for full-verify fix loop
coverage_threshold	85	Hard minimum — FAIL if below this %
skip_full_verify	false	true → skip full-verify phase

Precedence: defaults < .harness/config.json < invocation args

Read config: $ENGINE read-config [--max-spec-rounds N] [--max-eval-rounds N] ...

Architecture

Orchestrator (you, the Main Agent — Claude Code or Codex)
├── Planning Phase     → YOU are the Planner (direct user interaction)
│   ↕ spec-review/     → iterate with Spec Evaluator on checkpoint quality
├── Spec Evaluator     → sub-agent, architecture + feasibility
├── Generator          → sub-agent (or local in Codex), TDD skill preloaded
│   ↕ evaluation       → iterate with Evaluator per checkpoint
├── Evaluator          → sub-agent, composite sensor
└── Retro              → sub-agent, produces retro.md

Sub-agent dispatch: In Claude Code use Agent(subagent_type: "harness-*", prompt: <context>). In Codex use claude-agent-invoke.sh to dispatch via CLI. See references/codex-mode.md for Codex-specific details.

Anti-drift mechanisms:

• Fresh Generator + Evaluator per checkpoint (full eigenbehavior reset)
• SendMessage reuse within checkpoint iterations (bounded trade-off for efficiency)
• Two-session split: planning context discarded before execution
• Engine hard gates: pass-checkpoint requires latest evaluation.md verdict PASS plus fresh evaluator session proof (evaluator-session-id.txt not reused by prior checkpoints), pass-e2e requires latest e2e-report.md verdict PASS, and pass-review-loop requires a completed review-loop session.

File System Layout

.harness/
├── config.json                         # Project config (git-tracked)
├── <task-id>/                          # Per-task (gitignored)
��   ├── spec.md
│   ├── git-state.json
│   ├── spec-review/
│   │   ├��─ round-N-spec-review.md
│   │   ├── round-N-planner-response.md
│   │   └─��� status.md
│   ├── checkpoints/
│   │   └── NN/
│   │       ├── context.md
│   │       ├── iter-N/
���   │       │   ├── output-summary.md
│   │       │   ├── evaluation.md
│   │       │   ├── evaluator-session-id.txt
│   │       │   └── evidence/
│   │       └── status.md
│   ├── e2e/
│   │   ├── iter-N/ {context.md, e2e-report.md, evidence/}
│   ���   └── status.md
│   ├── full-verify/
│   │   ├── discovery.md
│   ��   ├── iter-N/
│   │   │   ├── verification-report.md
│   │   │   └── evidence/
│   │   └── status.md
│   └── retro-input.md
└── retro/                              # Persistent (git-tracked)
    ├���─ index.md
    └── <date>-<task-id>.md

Gitignore entries are auto-added by $ENGINE init.

Protocol Loading

This skill splits into two protocol files to minimize context usage. Read the one matching your intent before proceeding.

Intent	Trigger phrases	Action
Planning	"harness plan", "harness this task", "use harness", "harness spec"	Read references/planning-protocol.md
Execution	"harness continue", "harness execute <task-id>", "harness <spec-name>"	Read references/execution-protocol.md

After loading the protocol, follow it completely. Do not proceed without reading the appropriate reference file.

Reference Files

• references/planning-protocol.md — Session 1: spec creation and review (Claude Code recommended)
• references/execution-protocol.md — Session 2: checkpoint execution through retro (Codex recommended)
• references/protocol-quick-ref.md — All file format specs (passed to agents via prompt)
• references/checkpoint-definition.md — Checkpoint definition, numbering, granularity, scope constraint, and Planner guidance
• references/codex-mode.md — Codex-hosted sub-agent dispatch details