plan-format

A format for plan files that records feature requirements as Gherkin scenarios. Gherkin is a plain-language format using Given, When, and Then steps to describe expected behavior.

In plain words
What is it for?
Use it when creating plans, writing behavior requirements, or reading plan files with TODO and DONE markers.
Why use it?
It gives requirements and implementation progress a consistent, trackable structure in one source of truth.

Skill for Claude CodeCodex

Part of the tommymorgan plugin — 10 skills, 14 commands, 13 agents, 4 hooks shipped together

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

Made for: Claude Code, Codex.

Or install tommymorgan, the plugin that ships this one along with the rest of its 10 skills, 14 commands, 13 agents, 4 hooks.

Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,228 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 $0.00034 $0.01228
Opus 5 $0.00017 $0.00614
Sonnet 5 $0.00007 $0.00246
Haiku 4.5 $0.00003 $0.00123

Measured 3d ago against content hash c495ac2cf025, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plan-format 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 3d 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.

tommymorgan/planning/skills/plan-format/SKILL.md · 188 lines

How it starts

The opening of the file, as written. The whole thing — 188 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Plan File Format

Specification for plan files used by the tommymorgan plugin. Plan files capture feature requirements as Gherkin scenarios with TODO/DONE tracking.

Plan File Purpose

Plan files serve as the single source of truth for feature development:

  • Capture requirements as Gherkin scenarios (User Requirements + Technical Specifications)
  • Track progress via <!-- TODO --> / <!-- DONE --> comment markers
  • Enable autonomous TDD execution via the work command
  • Scenarios ARE the plan — no separate task lists

File Location

Plan files live in the project's plans directory:

<project>/plans/YYYY-MM-DD-<slug>.md

Where:

  • <project> is the project path (e.g., apps/web, libs/shared, tools/cli)
  • YYYY-MM-DD is the creation date
  • <slug> is a kebab-case version of the feature name

Example: apps/web/plans/2025-12-15-user-authentication.md

Plan File Template

# Feature: <Title>

**Created**: YYYY-MM-DD
**Goal**: <One-sentence description of user-facing outcome>

## User Requirements

<!-- TODO -->
# Living: <project>/features/<file>.feature::<scenario-name>
# Action: creates|replaces|extends|removes|deprecates
# Status: TODO
# Living updated: NO
Scenario: <user-focused behavior>
  Given <user context>
  When <user action>
  Then <user outcome>

## Technical Specifications

<!-- TODO -->
# Living: <project>/features/<file>.feature::<scenario-name>
# Action: creates|replaces|extends|removes|deprecates
# Status: TODO
# Living updated: NO
Scenario: <technical requirement>
  Given <system state>
  When <technical action>
  Then <technical outcome>

## Affected Documentation

- [ ] Update <path> — <brief description of needed update>

## Notes

<Design decisions, constraints, and context for future sessions>

Section Specifications

Header Section

Required fields:

  • **Created**: Date in YYYY-MM-DD format
  • **Goal**: Single sentence describing user-facing outcome

User Requirements Section

Language/framework agnostic Gherkin scenarios describing user-facing behavior.

Read the full file on GitHub · 188 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. 3d ago First seen · 188 lines · 34 tokens per session scan A c495ac2cf025

Subscribe to this mod's changes

plan-format is a skill published in the GitHub repository tommymorgan/claude-plugins (4 stars, last pushed 1mo ago), licensed MIT. It adds 34 tokens to every session and 1,228 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 2026-08-31.

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