A research and planning process that creates a detailed implementation plan for a codebase without writing code.

Use it to investigate an unfamiliar project, compare approaches, break large work into tasks, and save a plan for later coding.

It gives an engineer a map of the files, design choices, tests, and documentation involved before implementation begins.

plan — Skill for Claude Code and Codex by wrannaman

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 wrannaman/agentic-engineering --skill plan

Clone the repo

git clone --depth 1 https://github.com/wrannaman/agentic-engineering

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/wrannaman/agentic-engineering/plan/github.svg)](https://agentmods.dev/skills/wrannaman/agentic-engineering/plan)

Your own site

<a href="https://agentmods.dev/skills/wrannaman/agentic-engineering/plan"><img src="https://agentmods.dev/badge/skills/wrannaman/agentic-engineering/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/wrannaman/agentic-engineering/plan"><img src="https://agentmods.dev/badge/skills/wrannaman/agentic-engineering/plan.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,992 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.

Model	Per session	Once invoked
Fable 5.1	$0.00020	$0.01992
Opus 5.5	$0.00008	$0.00797
Sonnet 5.5	$0.00004	$0.00398
Haiku 4.5	$0.00002	$0.00199

Measured 2mo ago against content hash ecaabb6a6781, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

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 2mo 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/core/plan/SKILL.md · 189 lines

How it starts

The opening of the file, as written. The whole thing — 189 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Overview

Write comprehensive implementation plans assuming the engineer has zero context for our codebase and questionable taste. Document everything they need to know: which files to touch for each task, code, testing, docs they might need to check, how to test it. Give them the whole plan as bite-sized tasks. DRY. YAGNI. Frequent commits.

Assume they are a skilled developer, but know almost nothing about our toolset or problem domain. Assume they don't know good test design very well.

Announce at start: "I'm using the plan skill to create the implementation plan."

Save plans to: <harness-dir(.claude|.codex)>/plans/YYYY-MM-DD-.md

(User preferences for plan location override this default)

CRITICAL: This skill is research-first, then informed questions. Do exploration before asking questions so you can present trade-offs with clear recommendations. Don't ask questions you can answer through research.

Scope Check

If the spec covers multiple independent subsystems, it should have been broken into sub-project specs during brainstorming. If it wasn't, suggest breaking this into separate plans — one per subsystem. Each plan should produce working, testable software on its own.

Configuration

Learnings Directory: <git-root>/.llm/learnings/

If this directory does not exist in the current project, skip the learnings step entirely. Do NOT read ~/.agentic-eng/config.toml or any other config files to find an alternative path.

Process

ALL steps below are MANDATORY and SEQUENTIAL. Do NOT skip steps. Do NOT proceed to the next step until the current step is fully complete. Each step produces a required output — if a step has no output, the subsequent steps cannot succeed.

Step 1: Prime Context

Load all available context before exploring the codebase. KB and local learnings can be checked in parallel:

KB (if kb MCP is available): list_kb_documents → read_kb_document_by_path for relevant docs → read_kb_document_by_keywords for missing topics (retry up to 3×). Skip if unavailable.

Read the full file on GitHub · 189 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.

2mo ago First seen · 189 lines · 20 tokens per session scan A ecaabb6a6781

Subscribe to this mod's changes

plan is a skill published in the GitHub repository wrannaman/agentic-engineering (2 stars, last pushed 6mo ago), licensed MIT. It adds 20 tokens to every session and 1,992 once invoked, about $0.0001 per session on Opus 5.5. 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.

Planning

plan next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
planwrannaman/agentic-engineering	Skill	2	6mo ago	MIT	A	20	Claude Code, Codex
imagegenopenai/codex	Skill	134k	today	Apache-2.0	A	113	Codex
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	today	MIT	A	200	Claude Code, Codex
playwright-climicrosoft/playwright	Skill	99k	today	Apache-2.0	A	19	Claude Code
systematic-debuggingobra/superpowers	Skill	314k	3d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	today	MIT	A	95	Claude Code
chat-pet-sprite-creationmicrosoft/vscode	Skill	195k	today	MIT	A	53	Claude Code, Codex