packages/data-connect/src/network/stream/streamTransport.ts (581-586)

Throwing an error for an unrecognized requestId is too aggressive. In a streaming environment, it is common to receive "late" messages for requests that have already been cancelled or cleaned up on the client side (e.g., after an unsubscribe call). Throwing here will trigger a protocol error that closes the entire WebSocket connection, affecting all other active subscriptions. It is safer to simply ignore these messages.

    }

packages/data-connect/src/network/stream/websocket.ts (322-325)

The decodeBinaryResponse method should have more precise types. The input data can be an ArrayBuffer (when binaryType is set to 'arraybuffer') or a typed array, and the return type should be string rather than any. Additionally, creating a new TextDecoder instance for every message is slightly inefficient; consider making it a class member.

  private decodeBinaryResponse(data: ArrayBuffer | ArrayBufferView): string {
    const decoder = new TextDecoder('utf-8');
    return decoder.decode(data);
  }

packages/data-connect/src/network/stream/websocket.ts (144-147)

It is safer to always set binaryType to 'arraybuffer' regardless of whether the emulator is being used. If the emulator ever sends binary data in a browser environment, the default binaryType is 'blob', which TextDecoder cannot handle directly, leading to a runtime error in decodeBinaryResponse. Setting it to 'arraybuffer' ensures consistent behavior for all binary messages without affecting string-based messages.

      // prod sends as binary, emulator sends as JSON strings.
      // Setting binaryType to 'arraybuffer' ensures binary messages are handled consistently.
      this.connection!.binaryType = 'arraybuffer';

packages/data-connect/src/network/stream/streamTransport.ts (74-76)

Hardcoding isUnableToConnect to false effectively disables the fallback and error handling logic in DataConnectTransportManager. The manager relies on this property to decide whether to retry a failed streaming request via the REST transport. While the TODO notes this will be implemented later, the current state prevents the resilience features of the transport layer from functioning.