architecture-and-contracts

architecture-and-contracts is a skill for Claude Code from aneja5/forge-skills. It costs 55 tokens per session (1,805 once invoked), scanned A, original, MIT.

A design-planning skill that turns a product requirements document into a system architecture, module interfaces, and written records of important technical decisions.

In plain words
What is it for?
Use it to plan multi-module systems, define interfaces that separate engineers can implement independently, and record why unusual technical choices were made.
Why use it?
It gives engineers shared boundaries before they build, reducing integration surprises when several modules are developed at the same time.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the forge-skills plugin — 42 skills, 36 commands, 1 hook shipped together

Good fit Use it to plan multi-module systems, define interfaces that separate engineers can implement independently, and record why unusual technical choices were made.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/aneja5/forge-skills/architecture-and-contracts
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.

Any agent
npx skills add aneja5/forge-skills --skill architecture-and-contracts
Clone the repo
git clone --depth 1 https://github.com/aneja5/forge-skills

Made for: Claude Code.

Or install forge-skills, the plugin that ships this one along with the rest of its 42 skills, 36 commands, 1 hook.

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 architecture-and-contracts

README.md
[![agentmods](https://agentmods.dev/badge/skills/aneja5/forge-skills/architecture-and-contracts/github.svg)](https://agentmods.dev/skills/aneja5/forge-skills/architecture-and-contracts)
Your own site
<a href="https://agentmods.dev/skills/aneja5/forge-skills/architecture-and-contracts"><img src="https://agentmods.dev/badge/skills/aneja5/forge-skills/architecture-and-contracts/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 architecture-and-contracts

Your own site · 80×15
<a href="https://agentmods.dev/skills/aneja5/forge-skills/architecture-and-contracts"><img src="https://agentmods.dev/badge/skills/aneja5/forge-skills/architecture-and-contracts.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,805 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00055 $0.01805
Opus 5 $0.00028 $0.00903
Sonnet 5 $0.00011 $0.00361
Haiku 4.5 $0.00006 $0.00180

Measured 11d ago against content hash 085813e60aff, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

architecture-and-contracts 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 11d 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/architecture-and-contracts/SKILL.md · 142 lines

How it starts

The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Architecture and Contracts

Overview

Read .forge/prd.md and produce three artifacts: a system architecture document, precise interface contracts per module boundary, and ADRs for non-obvious decisions. Contracts must be specific enough that two engineers can implement different modules independently and integrate without surprises.

When to Use

  • .forge/prd.md exists and is complete
  • System has 2+ modules that need to interact
  • Team will work in parallel — contracts prevent integration failures
  • Non-obvious tech decisions need to be recorded with rationale

When NOT to Use

  • PRD doesn't exist yet — run spec-driven-development first
  • Trivial change touching only one module — skip straight to tdd
  • Architecture already exists and contracts are current — just update the affected contract

Common Rationalizations

Thought Reality
"We don't need contracts for a small feature" Contracts protect parallel workers — without them, work diverges
"I'll define interfaces as I implement" Interfaces defined during implementation encode accidents as decisions
"ADRs are bureaucratic overhead" ADRs are the only record of why — without them, decisions get relitigated
"The architecture is obvious from the PRD" Make the obvious explicit — it's where disagreements hide
"I can keep the architecture in my head" You can. Your parallel workers can't.

Red Flags

  • Contracts written at function level instead of module boundary level
  • Input/output types described in prose instead of typed schemas
  • "Error handling: TBD" in any contract
  • Architecture document names files and line numbers (these rot)
  • ADR is missing a "Decision" section — only has "Context"
  • .forge/contracts/ has no files after this skill runs

Core Process

Step 1: Read the PRD

Read .forge/prd.md. Identify: module list, interaction points, data flows, NFRs that impose architectural constraints.

Step 2: Explore existing architecture

Read the full file on GitHub · 142 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. 11d ago First seen · 142 lines · 55 tokens per session scan A 085813e60aff

Subscribe to this mod's changes

architecture-and-contracts is a skill published in the GitHub repository aneja5/forge-skills (3 stars, last pushed 3mo ago), licensed MIT. It adds 55 tokens to every session and 1,805 once invoked, about $0.0003 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 2026-08-31.