## Context
Helicone REST API returns `{ "error": "No API key found" }` for every endpoint, including `https://api.helicone.ai/v1/request/query`, even with a fresh read/write key, via header and via the `https://api.helicone.ai/sk-[key]/...` URL form. The reporter uses Azure OpenAI through the proxy.
## Verified resolution
Reporter self-solved and documented it (reporter, RowanAldean): two gotchas, (1) EU users must use `eu.api.helicone.ai` instead of `api.helicone.ai` (the key was provisioned in an EU region), and (2) the request/query endpoints require a well-formed JSON body from the docs or they return an unhelpful error. The examples/export typescript script also needs the `eu` prefix on the target URL.