A product is composable when another system can call it without a human in the loop. We expose orchestration as HTTP with a clear payload and a clear response.
When buyers ask "can we run this from our stack," the answer has to be yes or no. Yes means stable verbs, documented fields, and auth that fits server-to-server use. The OpenAPI specification is the usual way teams describe that contract. For protocol semantics, RFC 9110 still grounds how methods, caching, and representations behave; it is the boring reference that keeps integrations from arguing past each other.
What we do
We ship a versioned path for orchestration. API keys, rate limits, and JSON responses are part of the same story as the in-app "run mission" flow.
So what
If the web UI and the API are two different products, you do not have one platform. You have a demo and a side project. Align them, or be honest that partners are on their own.