Use when designing or reviewing an API surface — REST, GraphQL, or gRPC. Contract-first methodology: the contract artifact (OpenAPI 3.1, SDL, proto3) is written and reviewed BEFORE implementation, lives in the repo, and Phase 6 verifies implementation matches it.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# API Design — the contract IS the spec
Contract-first: write the machine-readable contract, review it like code, implement to it. Never code-first with docs generated after.
## Style selection (decision table — pick ONE, record an ADR)
| Use case | Style |
|---|---|
| Public/partner API, resource-shaped, broad client base | REST + OpenAPI 3.1 |
| Product frontend with many views over the same graph, client-driven field selection | GraphQL + SDL |
| Internal service-to-service, low latency, strong typing across languages | gRPC + proto3 |
Ambiguous → one question to the human with the trade-off, never two styles at once without justification.
## REST rules (OpenAPI 3.1)
- Contract file in-repo: `api/openapi.yaml` (or the repo's existing convention). Reviewed in the same PR discipline as code.
- Resources are plural nouns; no verbs in paths (`POST /orders`, not `/createOrder`). Consistent casing (pick kebab or snake for paths, camel for JSON; record it).
- Methods carry semantics: GET safe, PUT/DELETE idempotent, POST for creation/actions. Idempotency keys for payment-shaped POSTs.
…
The line at the top of this page pins the label git:20260703.c5a2b92, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.
pass: Frontmatter block present
pass: Frontmatter declares a name
pass: Frontmatter declares a description
pass: Size between 200 bytes and 200 KB (2806 bytes)
pass: No zero-width or bidi control characters
pass: No instruction hidden inside an HTML comment
pass: No link to an exfiltration or paste host
pass: No credential-shaped string
pass: No instruction to send local credentials anywhere
pass: No text hidden with inline styles
pass: No prompt-injection phrasing
pass: No curl or wget piped into a shell
pass: No recursive delete of root, home or parent
pass: No instruction to read or print local credentials
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pass: No script tag
Source
GitHub
jdanigo/hydraia · 8 stars · license MIT · pushed 2026-09-24 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_xtlxvpbt2apz4sqv
GET https://markdownregistry.com/api/v1/resolve?ref=jdanigo/hydraia/api-design
GET https://markdownregistry.com/api/v1/blob/fd11db1d17b4a7ea1df796e41fb6e692df9c7d8fbe8d337a776a1ffb94f5b985
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