AsyncAPI WebSocket Playground doesn't display binary frame messages

[bakharew]

AsyncAPI WebSocket Playground doesn't display binary frame messages

Description

The AsyncAPI WebSocket playground correctly connects and receives messages, but displays {} for incoming messages sent as binary WebSocket frames, even when the content is valid UTF-8 encoded JSON.

Steps to Reproduce

1. Create an AsyncAPI spec for a WebSocket endpoint that sends JSON messages as binary frames
2. Backend sends messages using binary WebSocket frames (e.g., in Python/aiohttp: ws.send_bytes(json.dumps(message).encode("utf-8")))
3. Connect to the WebSocket via the Mintlify AsyncAPI playground
4. Observe that received messages display as {}

Expected Behavior

Binary frames containing UTF-8 encoded JSON should be decoded and displayed in the playground, similar to how text frames are handled.

Actual Behavior

• Text frames (ws.send_str(json.dumps(message))) → Displayed correctly ✅
• Binary frames (ws.send_bytes(json.dumps(message).encode("utf-8"))) → Shows {} ❌

Verification

Switching the backend from send_bytes() to send_str() immediately fixes the display issue, confirming the playground receives the data but doesn't decode binary frames.

Environment

• AsyncAPI 3.0.0
• Binary frames contain valid UTF-8 JSON with contentType: application/json specified in the message schema

Context

This is how Google's Gemini Live API sends their WebSocket stream messages (binary frames with UTF-8 JSON), so supporting binary frame decoding is highly relevant for documenting real-world APIs.

[bakharew]

AsyncAPI Spec Note

The AsyncAPI WebSocket Message Bindings currently state: "This object MUST NOT contain any properties. Its name is reserved for future use."

This means there's no AsyncAPI-level way to specify binary vs text frame type. Since AsyncAPI doesn't distinguish between frame types, Mintlify should handle binary frames containing valid UTF-8 JSON gracefully by default.