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 agentmods add skills/phuoctrung-ppt/ai-sdlc-workflow/api-contract-firstnpx skills add phuoctrung-ppt/ai-sdlc-workflow --skill api-contract-firstgit clone --depth 1 https://github.com/phuoctrung-ppt/ai-sdlc-workflowWrote 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/phuoctrung-ppt/ai-sdlc-workflow/api-contract-first)<a href="https://agentmods.dev/skills/phuoctrung-ppt/ai-sdlc-workflow/api-contract-first"><img src="https://agentmods.dev/badge/skills/phuoctrung-ppt/ai-sdlc-workflow/api-contract-first.svg" alt="Measured on agentmods" 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 | $0.00034 | $0.00399 |
| Opus 5 | $0.00017 | $0.00199 |
| Sonnet 5 | $0.00007 | $0.00080 |
| Haiku 4.5 | $0.00003 | $0.00040 |
Grade A, and why
api-contract-first 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 4d 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.
What it actually says
API Contract First
Rule
The contract MUST be written and approved before @backend-worker or @frontend-worker implement the feature’s HTTP/API surface.
Owner of the contract artifact: @contract-agent → docs/contracts/YYYY-MM-DD-{feature}-contract.md (and shared types under packages/** when AGENTS.md §3 defines the package).
Format
Choose one source of truth from AGENTS.md §2 (Shared contracts):
- OpenAPI snippet in the contract file, or
- Zod schema in the shared types package (preferred when §2 names Zod)
Do not maintain conflicting shapes in both without generating one from the other.
Lock rule
After @contract-agent marks the contract approved, no worker may unilaterally change endpoint shapes. All changes go through @contract-agent first.
Breaking vs non-breaking
Breaking (requires contract-agent update + [BREAKING] tag + frontend notify):
- Rename a field
- Remove a field
- Change a field’s type
- Change the HTTP method
Non-breaking:
- Add an optional field
- Add a new endpoint
Workflow
- Plan approved → dispatch
@contract-agent - Contract approved → backend and frontend may start (in dependency order)
- Need a shape change →
@contract-agentupdates file → consumers adapt
Anti-patterns
- ❌ Implementing controllers/pages from a chat sketch with no contract file
- ❌ Frontend inventing response fields the backend never promised
- ❌ “We’ll sync types later” after both sides have shipped divergent shapes
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.
- 4d ago First seen · 50 lines · 34 tokens per session scan A a53f1f7ae0ba
api-contract-first is a skill published in the GitHub repository phuoctrung-ppt/ai-sdlc-workflow (2 stars, last pushed 18d ago), licensed MIT. It adds 34 tokens to every session and 399 once invoked, about $0.0002 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.
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