l4-ide: Skill for Claude Code

.claude/skills/writing-l4-rules/SKILL.md

writing-l4-rules is a skill for Claude Code from smucclaw/l4-ide. It costs 110 tokens per session (5,602 once invoked), scanned A, original, no licence file.

A skill for writing and checking L4, a typed programming language used to represent contracts, regulations, and policies as executable rules.

In plain words
What is it for?
Use it to formalise legal text, write rules with deadlines or reparations, and model obligations.
Why use it?
It helps turn legal or policy text into rules that can be checked for type errors and tested as decisions and obligations.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is smucclaw/l4-ide's own configuration. It tells Claude Code how to work on l4-ide itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything l4-ide configures →

Part of the l4-computational-law plugin — 1 skill shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to smucclaw/l4-ide. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/smucclaw/l4-ide/main/.claude/skills/writing-l4-rules/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/smucclaw/l4-ide

Made for: Claude Code.

Or install l4-computational-law, the plugin that ships this one along with the rest of its 1 skill.

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 writing-l4-rules

README.md
[![agentmods](https://agentmods.dev/badge/skills/smucclaw/l4-ide/writing-l4-rules/github.svg)](https://agentmods.dev/skills/smucclaw/l4-ide/writing-l4-rules)
Your own site
<a href="https://agentmods.dev/skills/smucclaw/l4-ide/writing-l4-rules"><img src="https://agentmods.dev/badge/skills/smucclaw/l4-ide/writing-l4-rules/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.

agentmods 80×15 button for writing-l4-rules

Your own site · 80×15
<a href="https://agentmods.dev/skills/smucclaw/l4-ide/writing-l4-rules"><img src="https://agentmods.dev/badge/skills/smucclaw/l4-ide/writing-l4-rules.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 110 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,602 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.00110 $0.05602
Opus 5 $0.00055 $0.02801
Sonnet 5 $0.00022 $0.01120
Haiku 4.5 $0.00011 $0.00560

Measured 11d ago against content hash f76df3a91e3b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

writing-l4-rules scanned grade A with 1 finding 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 11d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -X POST http://localhost:8080/deployments \
.claude/skills/writing-l4-rules/SKILL.md · 458 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

Files

What ships with it

6 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. 11d ago First seen · 458 lines · 110 tokens per session scan A f76df3a91e3b

Subscribe to this mod's changes

writing-l4-rules is a skill published in the GitHub repository smucclaw/l4-ide (37 stars, last pushed 1mo ago), with no licence file. It adds 110 tokens to every session and 5,602 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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