spec-driven-planning

spec-driven-planning is a skill for Codex from johnnykor82/spec-driven-planning. It costs 96 tokens per session (3,814 once invoked), scanned A, original, MIT.

A workflow for specifying, planning, carrying out, and checking substantial software work. It covers projects such as migrations, rewrites, roadmaps, and multi-phase feature builds.

In plain words
What is it for?
Use it for non-trivial changes, especially work spanning many steps, sessions, or phases, or when an existing project specification must guide execution.
Why use it?
It makes requirements and scope explicit before implementation, then checks the finished work against the agreed specification.

Skill for Codex

Written for Codex: agents/openai.yaml present.

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/johnnykor82/spec-driven-planning/spec-driven-planning
Any agent
npx skills add johnnykor82/spec-driven-planning --skill spec-driven-planning
Clone the repo
git clone --depth 1 https://github.com/johnnykor82/spec-driven-planning

Made for: 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 spec-driven-planning

README.md
[![agentmods](https://agentmods.dev/badge/skills/johnnykor82/spec-driven-planning/spec-driven-planning.svg)](https://agentmods.dev/skills/johnnykor82/spec-driven-planning/spec-driven-planning)
Your own site
<a href="https://agentmods.dev/skills/johnnykor82/spec-driven-planning/spec-driven-planning"><img src="https://agentmods.dev/badge/skills/johnnykor82/spec-driven-planning/spec-driven-planning.svg" alt="Measured on agentmods" height="20"></a>
Per session 96 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,814 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 5.1 $0.00096 $0.03814
Opus 5 $0.00048 $0.01907
Sonnet 5 $0.00019 $0.00763
Haiku 4.5 $0.00010 $0.00381

Measured 6d ago against content hash ff371e772516, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

spec-driven-planning 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 6d 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/spec-driven-planning/skills/spec-driven-planning/SKILL.md · 427 lines

How it starts

The opening of the file, as written. The whole thing — 427 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec-Driven Planning

Specify → Plan completely → Execute → Verify against spec. In that order. Every time.


When NOT to Use

  • Simple tasks with clear, unambiguous requirements (use planning-with-files instead)
  • Single-file changes or typo fixes
  • Tasks under ~10 tool calls or 3 steps
  • Quick fixes where requirements need no clarification
  • When all you need is a session plan, not a project plan

Exception: If .planning/ exists, or the user references an existing spec, roadmap, or plan, use Reference Mode below even for small tasks. Do not start the full two-pass workflow unless the task changes scope, conflicts with the spec, or lacks enough plan coverage.


Relationship to spec-driven-development (skill)

This skill picks up where the spec-driven-development skill leaves off.

spec-driven-development owns the SPECIFY phase: surfacing assumptions, reframing requirements, and writing the initial spec with human review. THIS skill owns everything AFTER the spec is approved: decomposing it into a hierarchical plan, executing with compliance verification, and managing scope changes.

IF NO SPEC EXISTS when this skill loads — load spec-driven-development first and complete its Specify phase. Then return here to plan.

Key boundary:

  • Before spec approval: spec is a LIVING document (spec-driven-development)
  • After spec approval: spec is IMMUTABLE without explicit user instruction (this skill, via Scope Change Protocol)

FIRST: Restore Context

Before doing anything else, check for existing planning files:

ls .planning/ 2>/dev/null && echo "planning dir found" || echo "new project"

If .planning/ exists:

  1. Read .planning/spec.md
  2. Read .planning/roadmap.md
  3. Resolve the active path (see § Active Path below)
  4. Read only the plan files along the active path
  5. Read .planning/progress.md (last session entry only)

Then continue from where work left off. Do NOT re-plan what is already planned.

If .planning/ does NOT exist, or spec.md is missing:

  1. Load the spec-driven-development skill
  2. Complete its Specify phase to create and approve the spec
  3. Then return here to build the plan hierarchy

Read the full file on GitHub · 427 lines

Files

What ships with it

7 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. 6d ago First seen · 427 lines · 96 tokens per session scan A ff371e772516

Subscribe to this mod's changes

spec-driven-planning is a skill published in the GitHub repository johnnykor82/spec-driven-planning (2 stars, last pushed 2mo ago), licensed MIT. It adds 96 tokens to every session and 3,814 once invoked, about $0.0005 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.

Related

Other skills, from other repositories