tlaplus-from-source

A method for turning source code into a high-level TLA+ model. TLA+ is a language for describing system behavior and checking that concurrent or distributed systems obey important rules.

In plain words
What is it for?
Use it to analyze C, C++, Rust, or similar code, identify its essential state transitions, write a TLA+ specification, and propose invariants and properties to verify.
Why use it?
It helps reveal missing states, unsafe interactions, and incorrect assumptions without copying every implementation detail into the model.

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/tlaplus/agentskills/tlaplus-from-source
Any agent
npx skills add tlaplus/AgentSkills --skill tlaplus-from-source
Clone the repo
git clone --depth 1 https://github.com/tlaplus/AgentSkills

Made for: Claude Code, Codex.

Per session 79 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,950 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 $0.00079 $0.02950
Opus 5 $0.00039 $0.01475
Sonnet 5 $0.00016 $0.00590
Haiku 4.5 $0.00008 $0.00295

Measured 3d ago against content hash b097f1016742, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

tlaplus-from-source 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 3d 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/tlaplus-from-source/SKILL.md · 413 lines

How it starts

The opening of the file, as written. The whole thing — 413 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Generate High-Level TLA+ Model from Source Code

Create a TLA+ specification from source code by understanding the code's intent, abstracting implementation details, and focusing on the essential concurrent/distributed behavior.

Philosophy

TLA+ models should capture what the system does, not how it does it:

  • Focus on state transitions and their effects
  • Abstract away implementation details (memory management, error handling boilerplate)
  • Identify the core concurrent/distributed behavior worth verifying
  • Keep the model small enough to be tractable for model checking

Workflow Overview

┌─────────────────────────────────────────────────────────────────┐
│ Phase 1: Understand the Code                                    │
│   → What problem does it solve?                                 │
│   → What are the key functions and their purposes?              │
│   → What state is being managed?                                │
└─────────────────────────────────────────────────────────────────┘
                              ↓
┌─────────────────────────────────────────────────────────────────┐
│ Phase 2: Identify Abstractions                                  │
│   → What are the essential state variables?                     │
│   → What are the atomic actions?                                │
│   → What concurrency/ordering matters?                          │
└─────────────────────────────────────────────────────────────────┘
                              ↓
┌─────────────────────────────────────────────────────────────────┐
│ Phase 3: Write TLA+ Specification                               │
│   → Define constants and variables                              │
│   → Write Init and actions                                      │
│   → Define Next as disjunction of actions                       │
│   → Check specification syntax with TLC parser SANY             │
└─────────────────────────────────────────────────────────────────┘
                              ↓
┌─────────────────────────────────────────────────────────────────┐
│ Phase 4: Propose Properties                                     │
│   → Safety invariants                                           │
│   → Safety properties (what must be true at all times)          │
│   → Liveness properties (what must eventually happen)           │
└─────────────────────────────────────────────────────────────────┘

Read the full file on GitHub · 413 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. 3d ago First seen · 413 lines · 79 tokens per session scan A b097f1016742

Subscribe to this mod's changes

tlaplus-from-source is a skill published in the GitHub repository tlaplus/AgentSkills (36 stars, last pushed 7mo ago), licensed MIT. It adds 79 tokens to every session and 2,950 once invoked, about $0.0004 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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