OpenAPI spec → Cloudflare Worker service binding.

capa generates deployable Workers from OpenAPI specs, so another Worker can call them through a service binding instead of hand-writing an API wrapper.

Every method returns the upstream result plus a JSON evidence bundle:

const { result, evidence } = await env.STRIPE.charges.create({
	amount: 1000,
	currency: "usd",
	source: "tok_visa",
});
if (evidence.verdict === "fail") {
	return Response.json({ error: "verification failed", evidence }, { status: 502 });
}
return Response.json({ chargeId: result.id, evidence });

Bindings are generated from OpenAPI specs. The hand-written layer is src/index.ts plus optional evidence overrides in src/overrides.ts.

Repo

Generated bindings

Validate

bun install
bun run check

bun run check is the fast, credential-free gate: regenerate known specs, typecheck every capability + harness, and run wrangler deploy --dry-run for every Worker. Live API smoke tests are opt-in via tests/harness/.

A weekly GitHub Action also runs bun run spec:watch. It only fetches and hashes registered upstream OpenAPI specs; if one changed, the action fails with a Markdown report artifact so a maintainer can regenerate deliberately.

Use a binding

Deploy a capability, set its upstream secret, then bind it from another Worker.

cd capabilities/stripe
wrangler secret put STRIPE_API_KEY
wrangler deploy

const { result, evidence } = await env.STRIPE.charges.create({
	amount: 1000,
	currency: "usd",
	source: "tok_visa",
});

Generate a binding

You can generate a binding locally and keep it private. If the API is broadly useful, contributions to this repo are welcome. Maintainers can also use Actions → Add Capability to feed a new public spec into main and get a generated capability scaffold.