harness-plan

harness-plan is a skill for Claude Code from vasuag09/harness-claude. It costs 64 tokens per session (791 once invoked), scanned A, original, MIT.

A single command that coordinates the planning stage of a non-trivial software change. It clarifies the request, checks whether existing code can be reused, creates a work plan, reviews that plan, and considers system design when needed.

In plain words
What is it for?
Use it at the beginning of a substantial feature or change when you need specifications, research, a phased plan, and a plan review.
Why use it?
It turns a vague feature request into agreed requirements and checked work steps before coding starts. It pauses for answers at important decision points.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions subagents.

Part of the harness-claude plugin — 32 skills, 8 agents, 6 hooks, 3 MCP servers shipped together

Good fit Use it at the beginning of a substantial feature or change when you need specifications, research, a phased plan, and a plan review.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vasuag09/harness-claude/harness-plan
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add vasuag09/harness-claude --skill harness-plan
Clone the repo
git clone --depth 1 https://github.com/vasuag09/harness-claude

Made for: Claude Code.

Or install harness-claude, the plugin that ships this one along with the rest of its 32 skills, 8 agents, 6 hooks, 3 MCP servers.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for harness-plan

README.md
[![agentmods](https://agentmods.dev/badge/skills/vasuag09/harness-claude/harness-plan/github.svg)](https://agentmods.dev/skills/vasuag09/harness-claude/harness-plan)
Your own site
<a href="https://agentmods.dev/skills/vasuag09/harness-claude/harness-plan"><img src="https://agentmods.dev/badge/skills/vasuag09/harness-claude/harness-plan/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for harness-plan

Your own site · 80×15
<a href="https://agentmods.dev/skills/vasuag09/harness-claude/harness-plan"><img src="https://agentmods.dev/badge/skills/vasuag09/harness-claude/harness-plan.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 64 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 791 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00064 $0.00791
Opus 5 $0.00032 $0.00396
Sonnet 5 $0.00013 $0.00158
Haiku 4.5 $0.00006 $0.00079

Measured 12d ago against content hash 913dcab60754, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

harness-plan scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/harness-plan/SKILL.md · 51 lines

How it starts

The opening of the file, as written. The whole thing — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/harness-plan — run the Plan phase

A thin orchestrator. It does not re-implement the sub-skills; it sequences them, enforces the gates, and stops for you at real decision points. Keep using the atomic skills (/harness-claude:spec, /harness-claude:plan, ...) directly when you only want one step.

Sequence

  1. /harness-claude:spec — clarify the request into a spec with testable acceptance criteria. → HALT and ask the user any load-bearing clarifying questions. Do not proceed on guesses. Resume once the spec's open questions are resolved.

  2. /harness-claude:research — reuse-first search (in-repo → context7 → registries/GitHub → web). Produce the build-vs-reuse decision; fold it into the spec.

  3. /harness-claude:plandelegate to the harness-claude:planner agent (pass it the spec + reuse decision + the objective, not just a query). Return a phased plan (tasks with write-sets + depends_on + the AC-n each addresses) with per-task exit checks.

  4. /harness-claude:plan-check — gate the plan against the spec (criteria coverage, scope, parallel-task disjointness) before any code. Delegate to the harness-claude:planner agent in a read-only check pass. Loop ≤3 revisions with /harness-claude:plan on findings. → HALT and show the user the checked plan for approval before any code. A standing Critical finding blocks the phase.

  5. Design gate — two independent, conditional siblings. A change can need one, both, or neither; run only what's relevant and say which you skipped.

    • /harness-claude:architectonly if the plan flagged a load-bearing system decision (new subsystem, public interface/data model, cross-cutting change, multi-shape refactor). Delegate to the harness-claude:architect agent and present the ADR.
    • /harness-claude:designonly if the change has a user-facing surface (page, screen, component, form, mobile, CLI/TUI presentation). Produce the design brief. → HALT for approval on whichever ran. If the work is routine and internal (no UI, no load-bearing design — like this CLI harness itself), skip both and say so.

Read the full file on GitHub · 51 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 51 lines · 64 tokens per session scan A 913dcab60754

Subscribe to this mod's changes

harness-plan is a skill published in the GitHub repository vasuag09/harness-claude (2 stars, last pushed 2mo ago), licensed MIT. It adds 64 tokens to every session and 791 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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