[bot] OpenAI Realtime API (WebSocket) not instrumented

[braintrust-bot]

Gap description

The openai-java SDK v2.15.0+ exposes a WebSocket-based Realtime API under client.beta().realtime(). The current instrumentation in openai_2_15_0 works by wrapping the SDK's HttpClient interface (execute / executeAsync), which only intercepts HTTP/HTTPS requests. WebSocket connections are established through a separate code path and are never passed through TracingHttpClient, so no span is created for any Realtime API session.

Affected surface

SDK	API surface	Transport
com.openai:openai-java:2.15.0+	client.beta().realtime()	WebSocket (WSS)

Why it matters

Realtime API sessions carry voice and text generation work that is billable and latency-sensitive — exactly the kind of LLM execution Braintrust is designed to observe. Without instrumentation, users see a complete blind spot for this API even when all other OpenAI calls are traced.

Analogous gap already tracked

Issue #120 tracks the same problem for the Google GenAI Live (streaming) API, which also uses a persistent bidirectional connection that bypasses the HTTP-layer hook.

Suggested approach

1. Identify the WebSocket-abstraction interface in openai-java (likely WebSocket or a RealtimeClient).
2. Use ByteBuddy to intercept session open/message/close events, or wrap the WebSocket factory the same way TracingHttpClient wraps HttpClient.
3. Accumulate audio/text deltas and emit a span on session close with braintrust.input_json / braintrust.output_json and token metrics where available.

Notes

• This gap exists only in the openai_2_15_0 module; no other provider currently wraps a WebSocket transport.
• If the upstream SDK does not yet expose a stable hook point, a note in the docs would at minimum set user expectations.