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.
npx skills add iradoweck/antigravity-awesome-skills --skill api-contract-testinggit clone --depth 1 https://github.com/iradoweck/antigravity-awesome-skillsWrote 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.
[](https://agentmods.dev/skills/iradoweck/antigravity-awesome-skills/api-contract-testing)<a href="https://agentmods.dev/skills/iradoweck/antigravity-awesome-skills/api-contract-testing"><img src="https://agentmods.dev/badge/skills/iradoweck/antigravity-awesome-skills/api-contract-testing/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.
<a href="https://agentmods.dev/skills/iradoweck/antigravity-awesome-skills/api-contract-testing"><img src="https://agentmods.dev/badge/skills/iradoweck/antigravity-awesome-skills/api-contract-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00028 | $0.01235 |
| Opus 5.5 | $0.00011 | $0.00494 |
| Sonnet 5.5 | $0.00006 | $0.00247 |
| Haiku 4.5 | $0.00003 | $0.00123 |
Grade A, and why
api-contract-testing 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 yesterday.
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.
This is a copy
100% identical to api-contract-testing — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Contract Testing
Overview
Turn an API change into explicit provider and consumer checks. Start from the actual contract and affected clients, then verify wire-level behavior rather than relying on generated types or a successful build. Default to local fixtures and existing test tools; this skill does not provision a testing service.
When to Use
- A response field, endpoint, event schema or error envelope changes.
- A client and server build successfully but disagree at runtime.
- A team needs to distinguish a breaking change from a compatible extension.
- A reported regression needs a minimal provider/consumer reproduction.
Do not use this as authorization to call production endpoints, bypass access controls or publish a new API version.
How It Works
1. Bind the contract and scope
Identify the provider, transport, contract source and version, known consumers and the requested behavior. Read the real OpenAPI/JSON Schema/protobuf definition or documented examples and the corresponding server/client code. Record missing consumers and stale specifications as coverage gaps; do not invent interfaces or claim complete coverage from one client.
Keep these distinct: documented schema, actual provider output, generated client types and runtime parsing. A type assertion alone is not validation. Preserve the existing protocol and test runner instead of introducing a new platform by default.
2. Classify the change
Review fields, requiredness, nullability, enum values, status codes, headers, content type, pagination and error behavior. Inspect whether clients tolerate extra fields and unknown enum values. Even an added optional field can break a strict consumer. Explicitly identify affected versions and assumptions before calling a change compatible.
For events, include duplicate delivery, ordering and version envelopes. For request changes, check serialization and server validation as well as responses.
3. Build a small test matrix
Use deterministic synthetic fixtures for:
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.
- yesterday First seen · 117 lines · 28 tokens per session scan A 204dad386d8b
api-contract-testing is a skill published in the GitHub repository iradoweck/antigravity-awesome-skills (30 stars, last pushed 2d ago), licensed MIT. It adds 28 tokens to every session and 1,235 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to api-contract-testing, differing in 0 lines, and is treated as a copy.
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