plan

A reviewed implementation plan for coding tasks that are large enough to involve several files or possible approaches. It identifies the work, affected files, risks, and recommended solution before coding begins.

In plain words
What is it for?
Use it to plan new features, refactors, and other non-trivial changes. The resulting plan can be handed to someone—or another coding agent—to build.
Why use it?
It reduces the chance of starting with a wrong assumption or duplicating code that already exists. A separate review challenges the plan before 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/mtthsnc/tempest/plan
Any agent
npx skills add mtthsnc/tempest --skill plan
Clone the repo
git clone --depth 1 https://github.com/mtthsnc/tempest

Made for: Claude Code, Codex.

Per session 71 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 813 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 $0.00071 $0.00813
Opus 5 $0.00036 $0.00407
Sonnet 5 $0.00014 $0.00163
Haiku 4.5 $0.00007 $0.00081

Measured 2d ago against content hash ba777c3e1c77, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 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.

plugins/tempest/skills/plan/SKILL.md · 64 lines

How it starts

The opening of the file, as written. The whole thing — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.

plan — produce a reviewed implementation plan

Overview

The front of the factory. Turn a task into a plan that is concrete enough to execute and honest about its risks — before any code is written. A good plan names the files it will touch, reuses what already exists, and has survived its own strongest objection.

This is a STARTER skill — a generic spine. Rewrite the procedure and the review lenses below to encode your own engineering opinions and standards.

The plan is the output. You do not implement here; you produce a plan a build step can follow.

Procedure

1. Understand before proposing

  • Restate the task in one sentence. If that sentence is ambiguous, ask the user now — a wrong assumption is cheapest to fix here.
  • Explore the codebase for existing functions, utilities, and patterns that already do part of this. Prefer reusing them over writing new code. Note the concrete file paths.
  • Identify the smallest change that fully satisfies the task.

2. Draft the plan

Write a plan with these parts:

  • Context — why this change, what problem it solves, the intended outcome.
  • Approach — the recommended approach only (not a survey). Name the trade-off you accepted.
  • Changes — the files to create/modify, each with a one-line description of what changes. For a pattern repeated across many files, describe it once and list a few representative paths.
  • Reuse — existing functions/utilities (with paths) the build should call instead of reinventing.
  • Verification — how to prove it works end-to-end: the command to run, the test to add, the behavior to observe.
  • Risks / unknowns — what could go wrong and what you are unsure about.

3. Review it against itself

Before presenting, attack your own plan from these lenses (collapse or extend to taste):

  • Correctness — does it actually satisfy the restated task? Any missed case?
  • Scope — is anything in here not required? Cut it. Is anything required missing? Add it.
  • Simplicity / reuse — is there an existing pattern that makes a chunk of this unnecessary?
  • Reversibility — if this is wrong, how hard is it to undo? Prefer the more reversible path.

Read the full file on GitHub · 64 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 · 64 lines · 71 tokens per session scan A ba777c3e1c77

Subscribe to this mod's changes

plan is a skill published in the GitHub repository mtthsnc/tempest (2 stars, last pushed 2mo ago), licensed MIT. It adds 71 tokens to every session and 813 once invoked, about $0.0004 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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