A planning gate for coding work that classifies the request, checks its scope and technology choices, and creates a written plan before code changes begin.

Use it at the start of new builds, bug fixes, and changes to review project scope, estimate the work, choose compatible technologies, and save the plan.

It prevents work from starting without agreed requirements, a suitable technology approach, and a recorded plan.

plan — Skill for Claude Code by lantisprime/claude-sdlc

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo

git clone --depth 1 https://github.com/lantisprime/claude-sdlc

agentmods

npx agentmods add skills/lantisprime/claude-sdlc/plan

Made for: Claude Code.

Or install sdlc-plugin, the plugin that ships this one along with the rest of its 18 skills, 16 commands, 10 agents, 4 hooks.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/lantisprime/claude-sdlc/plan/github.svg)](https://agentmods.dev/skills/lantisprime/claude-sdlc/plan)

Your own site

<a href="https://agentmods.dev/skills/lantisprime/claude-sdlc/plan"><img src="https://agentmods.dev/badge/skills/lantisprime/claude-sdlc/plan/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/lantisprime/claude-sdlc/plan"><img src="https://agentmods.dev/badge/skills/lantisprime/claude-sdlc/plan.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 130 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,847 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00130	$0.02847
Opus 5.5	$0.00052	$0.01139
Sonnet 5.5	$0.00026	$0.00569
Haiku 4.5	$0.00013	$0.00285

Measured 1mo ago against content hash 05e7595e4ac6, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 1mo 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.

skills/plan/SKILL.md · 193 lines

How it starts

The opening of the file, as written. The whole thing — 193 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Plan (Phase 1)

Produce a plan artifact before any code is touched. The plan-gate hook blocks Edit/Write until this file exists.

Step 1 — Classify the work item

Ask (or infer from context) which of these the request is:

New build — a new feature or capability not previously delivered
Fix — a correction to existing behavior
Change request (CR) — a modification to previously agreed scope

The classification drives different validation downstream (Phase 4 Build).

Step 2 — Resolve scope

If .claude/sdlc/scope.md exists and is signed: read it and proceed. Run a quick re-validation check — if the plan task looks materially different from what scope.md describes, invoke scope-ingest in re-validate mode and surface the drift report before continuing.

If .claude/sdlc/scope.md does not exist: ask the human to point at source material (file path or paste text). Then invoke the scope-ingest agent, which produces a draft at .claude/sdlc/scope-drafts/<timestamp>.md. Show the draft to the human and wait for review. The human copies/renames it to .claude/sdlc/scope.md and signs it before the plan proceeds.

Fallback — no source material: if the human has no source to point at, ask for a one-paragraph scope statement and write .claude/sdlc/scope.md directly (existing behavior, preserved for minimal-friction cases).

Then validate the resolved scope against the work item:

New build: confirm the request is within documented scope. If not, surface a scope-delta and ask the human whether to (a) treat as a CR, (b) expand scope, or (c) defer.
Fix: confirm the fix addresses in-scope behavior. An out-of-scope fix is a CR in disguise.
CR: require a change-request ID. If missing, create one under .claude/sdlc/change-requests/CR-<n>.md using templates/change-request.md and ask the human for sign-off before continuing.

See agents/scope-ingest.md for accepted source formats and draft output spec.

Step 2.5 — Domain expert check

Read the full file on GitHub · 193 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.

1mo ago First seen · 193 lines · 130 tokens per session scan A 05e7595e4ac6

Subscribe to this mod's changes

plan is a skill published in the GitHub repository lantisprime/claude-sdlc (3 stars, last pushed 5mo ago), licensed MIT. It adds 130 tokens to every session and 2,847 once invoked, about $0.0005 per session on Opus 5.5. 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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