What is api-contract?

A workflow for designing the app's web API in Protocol Buffers first. Protocol Buffers are structured files that define data and service operations; the workflow then generates the documentation and web routes from them.

Use it before editing API definitions, API worker files, or review comments about routes, data resources, pagination, or deletion behavior.

It keeps the API definition in one place and reduces mismatches between the design, the Cloudflare Worker, documentation, and clients.

How richardthe3rd/cambridge-beer-festival-app configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to richardthe3rd/cambridge-beer-festival-app. 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/richardthe3rd/cambridge-beer-festival-app/main/.claude/skills/api-contract/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/richardthe3rd/cambridge-beer-festival-app

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/richardthe3rd/cambridge-beer-festival-app/api-contract/github.svg)](https://agentmods.dev/skills/richardthe3rd/cambridge-beer-festival-app/api-contract)

Your own site

<a href="https://agentmods.dev/skills/richardthe3rd/cambridge-beer-festival-app/api-contract"><img src="https://agentmods.dev/badge/skills/richardthe3rd/cambridge-beer-festival-app/api-contract/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/richardthe3rd/cambridge-beer-festival-app/api-contract"><img src="https://agentmods.dev/badge/skills/richardthe3rd/cambridge-beer-festival-app/api-contract.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 192 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 6,777 The whole file, excluding the scripts and references it only reads on demand.

Security scan C 1 finding. 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.

Model	Per session	Once invoked
Fable 5.1	$0.00192	$0.06777
Opus 5.5	$0.00077	$0.02711
Sonnet 5.5	$0.00038	$0.01355
Haiku 4.5	$0.00019	$0.00678

Measured 2mo ago against content hash c45778558531, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade C, and why

api-contract scanned grade C with 1 finding 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 2mo 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.

Recursive force deletehighDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

rm -rf cloudflare-worker/src docs/code/api/openapi

.claude/skills/api-contract/SKILL.md · 380 lines

How it starts

The opening of the file, as written. The whole thing — 380 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API contract (proto-first)

The whole API surface — CatalogService (read-only festival/drink catalogue) and MyFestivalService (personal state + aggregates) — is defined once as Protocol Buffers in proto/cambeerfestival/festival/v1alpha/*.proto. The proto is the source of truth. There is no gRPC server: google.api.http annotations on each RPC define its REST route, and an OpenAPI v3 document (docs/code/api/openapi/openapi.yaml, gitignored — always generated, never committed) is derived from the proto for the hand-written Cloudflare Worker and any HTTP client. That OpenAPI doc is published as a Redoc site to GitHub Pages on every push to main (.github/workflows/api-docs.yml); PRs get it attached as a downloadable artifact instead.

If you need the plain-English meaning of a term used below (AIP, D1, workerd, etag, keyset pagination, CalVer, ...), see skill reference — this skill assumes you already know what they mean and focuses on what this repo specifically does with them.

1. Doctrine, in one paragraph

Design the resource in proto first (message + service + google.api.http binding), never in the Worker. docs/code/api/openapi/openapi.yaml and cloudflare-worker/src/api-types.ts are generated artifacts — both are gitignored (proto/docs/code/api/.gitignore has openapi/; cloudflare-worker/.gitignore has src/). Never hand-edit either; if a type looks wrong, fix the .proto and regenerate. The same applies to packages/myfestival_client (gitignored at the repo root, packages/) — the generated Dart/Dio sync client for Flutter.

2. Edit workflow — exact commands

Run in this order after any .proto change (all dev-only tasks, so prefix MISE_ENV=dev off Claude Code Web; on Claude Code Web the .miserc.toml auto-env already includes dev, so plain ./bin/mise works there):

MISE_ENV=dev ./bin/mise run proto:format      # buf format -w — formats .proto in place
MISE_ENV=dev ./bin/mise run proto:lint        # buf lint — STANDARD ruleset (minus 2 exceptions, see §4)
MISE_ENV=dev ./bin/mise run proto:api-lint    # AIP design-guideline linter (googleapis/api-linter)
MISE_ENV=dev ./bin/mise run proto:generate    # buf generate -> docs/code/api/openapi/openapi.yaml

Read the full file on GitHub · 380 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.

2mo ago First seen · 380 lines · 192 tokens per session scan C c45778558531

Subscribe to this mod's changes

api-contract is a skill published in the GitHub repository richardthe3rd/cambridge-beer-festival-app (3 stars, last pushed today), licensed MIT. It adds 192 tokens to every session and 6,777 once invoked, about $0.0008 per session on Opus 5.5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Backend and APIs

api-contract next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
api-contractrichardthe3rd/cambridge-beer-festival-app	Skill	3	today	MIT	C	192	Claude Code
mem0-oss-to-platformmem0ai/mem0	Skill	68k	2d ago	Apache-2.0	A	217	Claude Code, Codex
azure-mgmt-botservice-dotnetmicrosoft/skills	Skill	3.2k	yesterday	MIT	A	78	Claude Code
fastapi-router-pymicrosoft/skills	Skill	3.2k	yesterday	MIT	A	46	Claude Code
dev-runtimelangwatch/langwatch	Skill	5.0k	yesterday	Apache-2.0	A	172	Claude Code
api-designericrisco/rsc-harness	Skill	503	2d ago	MIT	A	105	Claude Code, Codex
migrate-segw-to-raparc-mcp/arc-1	Skill	252	yesterday	MIT	A	106	Claude Code

cambridge-beer-festival-app: Skill for Claude Code