axum-harness: Skill for Claude Code

.agents/skills/contract-agent/SKILL.md

contract-agent is a skill for Claude Code, Codex from openclosed-org/axum-harness. It costs 72 tokens per session (661 once invoked), scanned A, original, Apache-2.0.

A coding workflow for maintaining shared contracts in a monorepo, a repository that contains multiple related services and packages. These contracts define shared data types, events, errors, and service communication rules.

In plain words
What is it for?
Use it when changing shared DTOs, event schemas, error types, contract documentation, generated protocol files, or contract validation tests.
Why use it?
It helps prevent services from disagreeing about data formats and detects contract drift, when implementations no longer match the shared definitions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents); mentions AGENTS.md.

This is openclosed-org/axum-harness's own configuration. It tells Claude Code and Codex how to work on axum-harness 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 axum-harness configures →

Reuse

Borrowing it

Nothing to install: this file belongs to openclosed-org/axum-harness. 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/openclosed-org/axum-harness/main/.agents/skills/contract-agent/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/openclosed-org/axum-harness

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 contract-agent

README.md
[![agentmods](https://agentmods.dev/badge/skills/openclosed-org/axum-harness/contract-agent.svg)](https://agentmods.dev/skills/openclosed-org/axum-harness/contract-agent)
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<a href="https://agentmods.dev/skills/openclosed-org/axum-harness/contract-agent"><img src="https://agentmods.dev/badge/skills/openclosed-org/axum-harness/contract-agent.svg" alt="Measured on agentmods" height="20"></a>
Per session 72 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 661 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 $0.00072 $0.00661
Opus 5 $0.00036 $0.00331
Sonnet 5 $0.00014 $0.00132
Haiku 4.5 $0.00007 $0.00066

Measured 8d ago against content hash a0a485271aa2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

contract-agent 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 8d 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/skills/contract-agent/SKILL.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Contract Agent

You maintain the shared protocol definitions for the monorepo.


Responsibility

  1. Own packages/contracts/** — HTTP DTOs, event schemas, error types
  2. Own docs/contracts/** — contract documentation
  3. Own verification/contract/** — contract validation tests
  4. Run type generation after contract changes
  5. Detect and report contract drift
  6. Keep contracts aligned with service-local semantics and workflow expectations

Read Before Editing

AGENTS.md                                → global protocol
agent/codemap.yml                        → module constraints
.agents/skills/backend-engineering/SKILL.md → backend quality kernel
services/<name>/model.yaml               → commands/events/queries source context
platform/model/workflows/**              → workflow-driven protocol context
docs/contracts/**                        → existing contract documentation

Writable Directories

Directory Scope
packages/contracts/** Source contract types
docs/contracts/** Contract documentation
verification/contract/** Contract validation tests

Forbidden Directories

Directory Reason
packages/sdk/** Generated from contracts (read-only)
docs/generated/** Generated (read-only)
services/** Owned by service-agent
servers/** Owned by server-agent
workers/** Owned by worker-agent
infra/** Owned by platform-ops-agent
packages/**/adapters/** Concrete adapter implementations

Gate Candidates

Select gates from agent/manifests/gate-matrix.yml based on changed paths, risk, and evidence level. Common contract signals include:

Gate Command
Type generation moon run repo:typegen
Contract drift check git diff --exit-code packages/contracts/generated/
Typecheck just typecheck
Boundary check just boundary-check

Hard Rules

Workflow skills, including backend-engineering, may guide process; this skill's ownership boundaries still apply.

Read the full file on GitHub · 96 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. 8d ago First seen · 96 lines · 72 tokens per session scan A a0a485271aa2

Subscribe to this mod's changes

contract-agent is a skill published in the GitHub repository openclosed-org/axum-harness (49 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 72 tokens to every session and 661 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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