lat-md

lat-md is a skill for Claude Code, Codex from vercel-labs/lat.md. It costs 42 tokens per session (1,387 once invoked), scanned A, original, MIT.

A guide for writing lat.md files, structured Markdown documents that record a project's architecture, design decisions, domain rules, and test specifications.

In plain words
What is it for?
Create, edit, or review files in the lat.md directory.
Why use it?
It helps keep important project reasoning documented without copying step-by-step details from the source code.

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/vercel-labs/lat.md/skill
Any agent
npx skills add vercel-labs/lat.md --skill skill
Clone the repo
git clone --depth 1 https://github.com/vercel-labs/lat.md

Made for: Claude Code, 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 lat-md

README.md
[![agentmods](https://agentmods.dev/badge/skills/vercel-labs/lat.md/skill.svg)](https://agentmods.dev/skills/vercel-labs/lat.md/skill)
Your own site
<a href="https://agentmods.dev/skills/vercel-labs/lat.md/skill"><img src="https://agentmods.dev/badge/skills/vercel-labs/lat.md/skill.svg" alt="Measured on agentmods" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,387 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 $0.00042 $0.01387
Opus 5 $0.00021 $0.00694
Sonnet 5 $0.00008 $0.00277
Haiku 4.5 $0.00004 $0.00139

Measured 2d ago against content hash d978d5cd2ef3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

lat-md 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.

templates/skill/SKILL.md · 198 lines

How it starts

The opening of the file, as written. The whole thing — 198 lines — stays where its author put it; the contents beside it link to each section on GitHub.

lat.md Authoring Guide

This skill covers the syntax, structure rules, and conventions for writing lat.md/ files. Load it whenever you need to create or edit sections in the lat.md/ directory.

Project-specific lat documentation belongs in lat.md/. Do not modify this generated skill or a generated AGENTS.md to record project guidance: both are owned by lat tooling and may be replaced by a later lat init.

What belongs in lat.md

lat.md/ files describe what the project does and why — domain concepts, key design decisions, business logic, and test specifications. They do NOT duplicate source code. Think of each section as an anchor that source code references back to.

Treat lat.md/ as a focused snapshot of the current state of affairs or planned features. Do not use it as a journal or changelog, and do not grow it just to record insignificant implementation details.

Good candidates for sections:

  • Architecture decisions and their rationale
  • Domain concepts and business rules
  • API contracts and protocols
  • Test specifications (what is tested and why)
  • Non-obvious constraints or invariants

Bad candidates:

  • Step-by-step code walkthroughs (the code itself is the walkthrough)
  • Auto-generated API docs (use tools for that)
  • Journal/changelog entries for each change
  • Temporary notes or TODOs
  • Insignificant implementation details that do not change the current-state model

Section structure

Every section must have a leading paragraph — at least one sentence immediately after the heading, before any child headings or other block content.

The first paragraph must be ≤250 characters (excluding [[wiki link]] content). This paragraph is the section's identity — it appears in search results, command output, and RAG context.

# Good Section

Brief overview of what this section documents and why it matters.

More detail can go in subsequent paragraphs, code blocks, or lists.

## Child heading

Details about this child topic.

Read the full file on GitHub · 198 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 Changed · +12 lines d978d5cd2ef3
  2. 4d ago First seen · 186 lines · 42 tokens per session scan A 3c4411c80318

Subscribe to this mod's changes

lat-md is a skill published in the GitHub repository vercel-labs/lat.md (1,882 stars, last pushed 2d ago), licensed MIT. It adds 42 tokens to every session and 1,387 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 2026-08-30.

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