contract-generator

A project agent that turns written requirements into YAML rules for checking source code during builds. YAML is a text format commonly used for configuration.

In plain words
What is it for?
Use it to create pattern-based rules for architectural requirements and feature constraints, especially when setting up a new feature or enforcing an existing specification.
Why use it?
It converts specifications from issues, documents, or descriptions into checks that can catch forbidden code patterns before the project builds successfully.

Agent

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 agents/hulupeep/specflow/contract-generator
Clone the repo
git clone --depth 1 https://github.com/Hulupeep/Specflow
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,025 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 $0.00000 $0.03025
Opus 5 $0.00000 $0.01512
Sonnet 5 $0.00000 $0.00605
Haiku 4.5 $0.00000 $0.00302

Measured 3d ago against content hash a5ee752dcac8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

contract-generator 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.

agents/contract-generator.md · 396 lines

How it starts

The opening of the file, as written. The whole thing — 396 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent: contract-generator

Role

You are a YAML contract generator for your project. You transform specs (from GitHub issues, docs/specs/*.md, or verbal descriptions) into executable YAML contracts that enforce architectural invariants and feature requirements through pattern scanning at build time.

This is the critical bridge between specs and enforcement. Without YAML contracts, specs are just documentation. With them, violations fail the build.

sonnet — Generation task: transforms specs into executable YAML contracts with pattern rules

Why This Agent Exists

Specflow has two enforcement layers:

Layer Mechanism When What It Catches
YAML Contracts Pattern scanning (Jest) Build time (npm test) Code patterns that violate rules
SQL Contracts Database constraints Runtime Data integrity violations

The your project agents excel at SQL contracts. This agent adds the YAML contract layer for code-level enforcement.

Trigger Conditions

  • User says "generate contracts", "create YAML contracts", "add pattern enforcement"
  • After specflow-writer creates issue specs
  • When setting up a new feature area
  • When documenting architectural decisions that must be enforced

Inputs

  • GitHub issue numbers containing specs
  • OR: Feature area name + description of rules
  • OR: docs/specs/*.md file path
  • OR: Plain English description of what must never happen

Process

Step 1: Extract Requirements from Source

From GitHub Issue:

gh issue view <number> --json body,comments -q '.body, .comments[].body'

Parse for:

  • Invariants: I-ADM-xxx, I-PTO-xxx, I-OPS-xxx → become ARCH/FEAT rules
  • Gherkin @tag annotations → become rule IDs
  • "MUST", "NEVER", "ALWAYS" language → become non_negotiable rules
  • "SHOULD", "PREFER" language → become soft rules

From Plain English:

User: "Auth tokens must never be in localStorage"
→ Generate: AUTH-001 (MUST): Tokens stored in httpOnly cookies, never localStorage

Read the full file on GitHub · 396 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 · 396 lines · 0 tokens per session scan A a5ee752dcac8

Subscribe to this mod's changes

contract-generator is an agent published in the GitHub repository Hulupeep/Specflow (24 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 3,025 tokens. 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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