| name | harness |
| description | Structured development harness that guides feature implementation through 5 phases — Clarify, Context Gather, Plan, Generate, Evaluate. Each phase runs as an independent sub-agent that produces artifacts for the next phase. Use this skill when starting a new feature, building a project from scratch, or implementing a complex requirement that benefits from structured planning before coding. Triggers on phrases like "build me X", "implement X", "new feature", "create an app that", or when the user explicitly invokes /harness. |
| disable-model-invocation | true |
| user-invocable | true |
| argument-hint | ["feature description"] |
Development Harness — Orchestrator
A structured 5-phase workflow where each phase is executed by an independent sub-agent. Artifacts flow between phases via .harness/artifacts/.
Overview
Phase 1: Clarify → Sub-Agent → artifacts/01-clarify.md
Phase 2: Context → Sub-Agent → artifacts/02-context.md
Phase 3: Plan → Sub-Agent → artifacts/03-plan.md + phases.json + tasks.json
Phase 4: Generate → Sub-Agent (per phase) → artifacts/04-generate.md
Phase 5: Evaluate → Sub-Agent → artifacts/05-evaluate.md
Artifact Pipeline
Each sub-agent reads previous phase artifacts and produces its own. All artifacts live in .harness/artifacts/.
01-clarify.md ──→ 02-context.md ──→ 03-plan.md ──→ 04-generate.md ──→ 05-evaluate.md
phases.json
tasks.json
How to use
The user provides a feature description as $ARGUMENTS. Execute each phase by spawning a sub-agent using the Agent tool. Get explicit user approval before advancing to the next phase.
Orchestration Flow
Step 0: Initialize
Create .harness/artifacts/ directory if it doesn't exist:
mkdir -p .harness/artifacts
Step 1: Clarify Phase
Spawn a sub-agent with the following:
- description: "Clarify phase - surface questions"
- prompt: Read the instructions from
.claude/skills/harness/phases/01-clarify.md and include $ARGUMENTS as the $FEATURE_DESCRIPTION. Tell the agent to write its output to .harness/artifacts/01-clarify.md.
After the agent completes:
- Read
.harness/artifacts/01-clarify.md and present the questions to the user
- Wait for the user's answers
- Update
.harness/artifacts/01-clarify.md — fill in the "User Decisions" section with the user's answers
Gate: Wait for explicit user approval before proceeding.
Step 2: Context Gather Phase
Spawn a sub-agent with the following:
- description: "Context gather - scan codebase"
- prompt: Read the instructions from
.claude/skills/harness/phases/02-context.md. The agent should read .harness/artifacts/01-clarify.md as input and write its output to .harness/artifacts/02-context.md.
After the agent completes:
- Read
.harness/artifacts/02-context.md and present the summary to the user
Gate: Wait for explicit user approval before proceeding.
Step 3: Plan Phase
Spawn a sub-agent with the following:
- description: "Plan phase - create execution plan"
- prompt: Read the instructions from
.claude/skills/harness/phases/03-plan.md. The agent should read .harness/artifacts/01-clarify.md and .harness/artifacts/02-context.md as input, then produce:
.harness/phases.json.harness/tasks.json.harness/artifacts/03-plan.md
After the agent completes:
- Read
.harness/artifacts/03-plan.md and present the plan summary table to the user
- If the user requests changes, spawn the Plan agent again with the feedback
Gate: Wait for explicit user approval before proceeding.
Step 4: Generate Phase
This phase runs one sub-agent per execution phase defined in .harness/phases.json.
For each phase in phases.json (in order):
-
Spawn a sub-agent with the following:
- description: "Generate phase - {phase_name}"
- prompt: Read the instructions from
.claude/skills/harness/phases/04-generate.md. Set $PHASE_ID to the current phase ID (e.g., "phase-1"). The agent should read all previous artifacts and implement only the tasks in that phase. It should update tasks.json statuses and append to .harness/artifacts/04-generate.md.
-
After the agent completes, briefly report progress to the user:
- Which tasks were completed
- Current overall progress (e.g., "Phase 2/6 complete, 4/9 tasks done")
-
Initialize .harness/artifacts/04-generate.md with a header before the first generate sub-agent:
# Phase 4: Generate — Artifact
Note: Each generate sub-agent runs sequentially (phase by phase), but tasks within a phase that have no inter-dependencies can be implemented in parallel by the agent.
Gate: After ALL phases are generated, wait for user approval before proceeding to evaluation.
Step 5: Evaluate Phase
Spawn a sub-agent with the following:
- description: "Evaluate phase - verify output"
- prompt: Read the instructions from
.claude/skills/harness/phases/05-evaluate.md. The agent should read all artifacts, run available checks, verify acceptance criteria, fix errors, and write results to .harness/artifacts/05-evaluate.md.
After the agent completes:
- Read
.harness/artifacts/05-evaluate.md and present the results to the user
- If there are remaining issues, report them clearly
Error Handling
- If a sub-agent fails or reports a blocker, present the issue to the user and ask how to proceed
- If a sub-agent's artifact is missing or malformed, re-run the phase
- The user can always say "redo phase N" to re-run any specific phase
State Management
All harness state lives in .harness/ at the project root:
.harness/
├── artifacts/
│ ├── 01-clarify.md # Phase 1 output: questions + user decisions
│ ├── 02-context.md # Phase 2 output: codebase context
│ ├── 03-plan.md # Phase 3 output: plan summary
│ ├── 04-generate.md # Phase 4 output: generation log
│ └── 05-evaluate.md # Phase 5 output: evaluation results
├── phases.json # Phase definitions (from Phase 3)
├── tasks.json # Task definitions with status (from Phase 3)
└── log.md # Legacy execution log (optional)
This directory can be safely deleted after the feature is complete, or kept for reference.
