plan-with-agent

plan-with-agent is a skill for Claude Code, Codex from Chachamaru127/codex-harness. It costs 65 tokens per session (888 once invoked), scanned A, original, MIT.

A planning workflow that turns an idea into an executable task list in Plans.md. TDD means writing tests before or alongside the code they check.

In plain words
What is it for?
Use it to plan features, organize a conversation into tasks, or create a test-first plan that another command can execute.
Why use it?
It turns vague requirements into ordered work and makes priorities and testing expectations explicit.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/chachamaru127/codex-harness/planning
Any agent
npx skills add Chachamaru127/codex-harness --skill planning
Clone the repo
git clone --depth 1 https://github.com/Chachamaru127/codex-harness

Made for: Claude Code, Codex.

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 plan-with-agent

README.md
[![agentmods](https://agentmods.dev/badge/skills/chachamaru127/codex-harness/planning.svg)](https://agentmods.dev/skills/chachamaru127/codex-harness/planning)
Your own site
<a href="https://agentmods.dev/skills/chachamaru127/codex-harness/planning"><img src="https://agentmods.dev/badge/skills/chachamaru127/codex-harness/planning.svg" alt="Measured on agentmods" height="20"></a>
Per session 65 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 888 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00065 $0.00888
Opus 5 $0.00032 $0.00444
Sonnet 5 $0.00013 $0.00178
Haiku 4.5 $0.00006 $0.00089

Measured 4d ago against content hash 9689eb71e55b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plan-with-agent 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 4d 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.

.codex/skills/planning/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Planning Skill

Organizes ideas and requirements, converting them into executable tasks in Plans.md.

Quick Reference

  • "Create a plan" → this skill
  • "Turn what we talked about into a plan" → extract from conversation
  • "Want to organize what to build" → start with hearing
  • "Plan with TDD" → force TDD adoption
  • "CI/benchmark" → --ci mode

Deliverables

  • Plans.md - Task list executable with /work (required)
  • Feature priority matrix - Required/Recommended/Optional classification

Usage

/plan-with-agent       # Interactive planning
/plan-with-agent --ci  # CI mode (non-interactive)

Mode-specific Usage

Mode Command Description
Solo mode /plan-with-agent Claude Code alone: plan → execute → review
2-agent mode /plan-with-cc (Cursor) Plan with Cursor → Execute with Claude Code

Feature Details

Feature Reference
Execution Flow See references/execution-flow.md
TDD Adoption See references/tdd-adoption.md
Priority Matrix See references/priority-matrix.md

Execution Flow Overview

  1. Step 0: Check conversation context (extract from previous conversation or start fresh)
  2. Step 1: Hearing what to build
  3. Step 2: Increase resolution (max 3 questions)
  4. Step 3: Technical research (WebSearch)
  5. Step 4: Extract feature list
  6. Step 5: Create priority matrix (Required/Recommended/Optional)
  7. Step 5.5: TDD adoption judgment and test design
  8. Step 6: Effort estimation (reference)
  9. Step 7: Generate Plans.md with quality markers
  10. Step 8: Guide next actions

Auto-invoke Skills

Skill When to Call
setup Call first (executes adaptive setup)
vibecoder-guide When user is non-technical

Quality Markers (Auto-assigned)

Read the full file on GitHub · 85 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 4d ago First seen · 85 lines · 65 tokens per session scan A 9689eb71e55b

Subscribe to this mod's changes

plan-with-agent is a skill published in the GitHub repository Chachamaru127/codex-harness (2 stars, last pushed 6mo ago), licensed MIT. It adds 65 tokens to every session and 888 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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