plan

A design workflow that turns accepted product requirements into a technical implementation plan without changing production code.

In plain words
What is it for?
Use it to plan a feature or system change, including its components, data model, API contract, migration approach, and test strategy.
Why use it?
It exposes important decisions about architecture, data, APIs, migrations, compatibility, and testing before coding begins.

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/rmjosea/agentic-sdlc-kit/plan
Any agent
npx skills add rmjosea/agentic-sdlc-kit --skill plan
Clone the repo
git clone --depth 1 https://github.com/rmjosea/agentic-sdlc-kit

Made for: Claude Code, Codex.

Per session 95 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 611 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 $0.00095 $0.00611
Opus 5 $0.00048 $0.00305
Sonnet 5 $0.00019 $0.00122
Haiku 4.5 $0.00010 $0.00061

Measured 2d ago against content hash ae7783447dc7, 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.

.agents/skills/plan/SKILL.md · 73 lines

How it starts

The opening of the file, as written. The whole thing — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Plan an Implementation

Convert approved product behavior into a technically coherent design. Do not modify production code.

Discover

  1. Read only the authoritative source intent and relevant repository guidance.
  2. Inspect the codebase, tests, dependencies, and established conventions.
  3. Identify constraints, reusable components, trust boundaries, and unknowns.
  4. Separate repository facts, confirmed constraints, assumptions, and choices.

Resolve decisions conversationally

For every material uncertainty, apply the human decision protocol in AGENTS.md:

  • ask one clear, self-contained question at a time;
  • offer distinct alternatives with consequences;
  • mark and justify the recommended option;
  • update the confirmed design after each answer.

Ask when a choice materially affects architecture, data, APIs, security, cost, operability, compatibility, reversibility, or task structure. Decide trivial, reversible, repository-standard details directly and record the rationale.

Do not write the final plan until material decisions are resolved and the user has confirmed the proposed technical direction.

Design

Cover only what the change needs:

  • components and responsibilities;
  • interfaces and integration points;
  • data ownership, model, and migration;
  • security and privacy boundaries;
  • failure handling and recovery;
  • compatibility and rollout;
  • observability;
  • verification strategy.

Create a separate technical artifact only when several tasks share it, it needs independent review, or moving it out materially reduces task context. Possible artifacts include architecture.md, data-model.md, api-contract.md, migration.md, and test-strategy.md.

Use assets/plan.template.md and write temporary planning artifacts under .work/<feature>/. Keep the plan draft while a material decision or user confirmation is pending; set it to approved only after the user confirms the complete technical direction.

Quality gate

Read the full file on GitHub · 73 lines

Files

What ships with it

1 file 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. 2d ago First seen · 73 lines · 95 tokens per session scan A ae7783447dc7

Subscribe to this mod's changes

plan is a skill published in the GitHub repository rmjosea/agentic-sdlc-kit (2 stars, last pushed 1mo ago), licensed MIT. It adds 95 tokens to every session and 611 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.

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