ck:plan

A planning tool for turning a software task into a technical implementation plan. It can cover research, system design, architecture, implementation phases, review, and validation.

In plain words
What is it for?
Use it to plan features, design systems, compare approaches, review plans for risks, and document technical roadmaps.
Why use it?
It gives developers a written path through complex work before they start changing code. This helps clarify decisions, dependencies, and the order of implementation.

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

Made for: Claude Code, Codex.

Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,331 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 $0.00035 $0.01331
Opus 5 $0.00017 $0.00665
Sonnet 5 $0.00007 $0.00266
Haiku 4.5 $0.00003 $0.00133

Measured 2d ago against content hash a86bb9cf1495, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ck: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 2d 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.

.agents/skills/plan/SKILL.md · 139 lines

How it starts

The opening of the file, as written. The whole thing — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Planning

Create detailed technical implementation plans through research, codebase analysis, solution design, and comprehensive documentation.

Default (No Arguments)

If invoked with a task description, proceed with planning workflow. If invoked WITHOUT arguments or with unclear intent, ask the user to choose an operation:

Operation Description
(default) Create implementation plan for a task
archive Write journal entry & archive plans
red-team Adversarial plan review
validate Critical questions interview

Present options with header "Planning Operation", question "What would you like to do?".

Workflow Modes

Default: --auto (analyze task complexity and auto-pick mode).

Flag Mode Research Red Team Validation Cook Flag
--auto Auto-detect Follows mode Follows mode Follows mode Follows mode
--fast Fast Skip Skip Skip --auto
--hard Hard 2 researchers Yes Optional (none)
--parallel Parallel 2 researchers Yes Optional --parallel
--two Two approaches 2+ researchers After selection After selection (none)

Add --no-tasks to skip task hydration in any mode.

Load: references/workflow-modes.md for auto-detection logic, per-mode workflows, context reminders.

When to Use

  • Planning new feature implementations
  • Architecting system designs
  • Evaluating technical approaches
  • Creating implementation roadmaps
  • Breaking down complex requirements

Core Responsibilities & Rules

Always honoring YAGNI, KISS, and DRY principles. Be honest, be brutal, straight to the point, and be concise.

1. Research & Analysis

Load: references/research-phase.md Skip if: Fast mode or provided with researcher reports

2. Codebase Understanding

Load: references/codebase-understanding.md Skip if: Provided with scout reports

Read the full file on GitHub · 139 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. 2d ago First seen · 139 lines · 35 tokens per session scan A a86bb9cf1495

Subscribe to this mod's changes

ck:plan is a skill published in the GitHub repository manhvann/codexkit (88 stars, last pushed 3d ago), licensed MIT. It adds 35 tokens to every session and 1,331 once invoked, about $0.0002 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 2026-08-30.

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