relay: Skill for Claude Code

HTTP in core SDK and protocol plugins should go through Effect services so tests can replace real networks with local protocol fixtures or mock HttpClient layers.

Fix Shape

• Prefer effect/unstable/http HttpClient and HttpClientRequest for ordinary HTTP calls.
• Accept a Layer.Layer<HttpClient.HttpClient> option on plugin/provider code when callers need to inject a test client.
• In tests, use real local servers plus FetchHttpClient.layer or a captured HttpClient service from the test layer.
• Do not add fetch-shaped abstractions in SDK or plugin seams. If a third-party library truly only accepts fetch, keep the adapter in the owning package, name the forced boundary explicitly, and delegate internally to Effect HttpClient.
• Do not type new protocol/plugin seams as typeof globalThis.fetch; keep the ambient runtime boundary out of domain and test APIs.
• Do not patch globalThis.fetch. Replace those tests with a local server, HttpClient layer, or the approved Effect-backed adapter.
• Do not add a broad allowlist entry unless the file is a platform entrypoint or a temporary migration target.

Approved Boundaries

• Worker/handler objects whose public API must expose a fetch method.
• Test calls to a worker or Miniflare binding's .fetch(...) method.
• Small adapters for libraries that only accept fetch, if the implementation delegates to Effect HttpClient.
• Browser UI event handlers may remain raw only until app-side boundaries are classified; prefer SDK/client APIs where available.

Bad

const response = await fetch(url);

const fetchImpl = options.fetch ?? globalThis.fetch;

Good

const client = yield * HttpClient.HttpClient;
const response = yield * client.execute(HttpClientRequest.get(url));

const plugin = graphqlPlugin({ httpClientLayer: testHttpClientLayer });