feat(realtime): introduce resultType="json"

[efiop]

Alternative to #178

[efiop]

I guess we could also introduce just raw for cases where you expect binary data to be sent over too, so your handler could deal with any serialization/etc on itsown.

Let me add that too...

Or maybe just do it as a handler option, hm...

[efiop]

introduced decodeMessage, encodeMessage, feels more appropriate and natural. Open to feedback.

[efiop]

So like for json:

import { createRealtimeClient, createConfig } from "@fal-ai/client";

const jsonCodec = {
  encodeMessage: (input: any) =>
    typeof input === "string" ? input : JSON.stringify(input),
  decodeMessage: async (data: any) => {
    const toText = async () => {
      if (typeof data === "string") return data;
      if (data instanceof Uint8Array) return new TextDecoder().decode(data);
      if (data instanceof ArrayBuffer)
        return new TextDecoder().decode(new Uint8Array(data));
      if (data instanceof Blob)
        return new TextDecoder().decode(new Uint8Array(await data.arrayBuffer()));
      return String(data);
    };
    return JSON.parse(await toText());
  },
};

const client = createRealtimeClient({
  config: createConfig({ credentials: process.env.FAL_KEY!, fetch }),
});

const conn = client.connect("your-app-id", {
  ...jsonCodec,
  onResult: (msg) => console.log("result", msg),
  onError: (err) => console.error("error", err),
});

// send plain JS objects; will be JSON-stringified
conn.send({ prompt: "hello json" });
// later
// conn.close();

and just to spice it up, say for protobuf (no need for protobuf, purely illustrative):

import { createRealtimeClient, createConfig } from "@fal-ai/client";
import { MyMessage } from "./generated/my_message"; // your protobufjs static module

const protobufCodec = {
  encodeMessage: (input: any) => {
    // expects input already shaped like MyMessage
    return MyMessage.encode(MyMessage.create(input)).finish(); // Uint8Array
  },
  decodeMessage: async (data: any) => {
    const toBytes = async () => {
      if (data instanceof Uint8Array) return data;
      if (data instanceof ArrayBuffer) return new Uint8Array(data);
      if (data instanceof Blob) return new Uint8Array(await data.arrayBuffer());
      throw new Error("Unsupported payload for protobuf decode");
    };
    return MyMessage.decode(await toBytes());
  },
};

const client = createRealtimeClient({
  config: createConfig({ credentials: process.env.FAL_KEY!, fetch }),
});

const conn = client.connect("your-app-id", {
  ...protobufCodec,
  onResult: (msg) => {
    // msg is a decoded protobuf message
    console.log("proto result", msg);
  },
  onError: (err) => console.error("proto error", err),
});

// send a protobuf-shaped object
conn.send({ prompt: "hello proto" });
// conn.close();