# Connection & Subscription

Lynx provides a single unified WebSocket endpoint for all channel categories — public market data, on-chain explorer events, and per-user updates.

> **No authentication required.** User channels are subscribed by `address`; any address is publicly observable.

## Endpoints

| Surface  | URL                       |
| -------- | ------------------------- |
| Standard | `ws://10.34.8.77:8481/v1` |

## Connection Rules

| Rule               | Detail                                                                                                 |
| ------------------ | ------------------------------------------------------------------------------------------------------ |
| Subscribe deadline | Send a `subscribe` message within **10 seconds** of opening the connection, or the server disconnects. |
| Channel limit      | **50 channel instances** per connection.                                                               |
| Compression        | `permessage-deflate` supported.                                                                        |
| Message format     | JSON, UTF-8.                                                                                           |

## Heartbeat

Send a ping every 30 seconds. The server disconnects after 60 seconds with no heartbeat.

```json
// Client → Server
{ "op": "ping" }

// Server → Client
{ "op": "pong", "time": 1719500000000 }
```

## Subscribing

```json
{
  "op": "subscribe",
  "args": [
    { "channel": "bbo", "symbol_id": 100001 },
    { "channel": "order", "address": "0xabc…def" }
  ]
}
```

```json
{ "op": "subscribe", "success": true, "args": [...] }
```

Unsubscribing is identical with `"op": "unsubscribe"`.

## Push Format

All channels share this envelope:

```json
{
  "channel": "<channel>",
  "symbol_id": "<symbol_id>",
  "type": "<type>",
  "ts": 1719500000000,
  "finality": "final",
  "data": { ... }
}
```

| Field       | Meaning                                                                                                                               |
| ----------- | ------------------------------------------------------------------------------------------------------------------------------------- |
| `channel`   | Channel name.                                                                                                                         |
| `symbol_id` | Present for market-data channels. Omitted for Explorer / User.                                                                        |
| `type`      | Sub-type identifier. Used where a channel emits multiple shapes (e.g. `l2_book` emits `"snapshot"` and `"delta"`). Omitted otherwise. |
| `ts`        | Server push time, Unix milliseconds.                                                                                                  |
| `finality`  | Always `"final"` — data is block-finalized before being pushed (3-block finality, ≈ 150 ms).                                          |
| `data`      | Channel-specific payload.                                                                                                             |

## Push Timing

> **All** channels push after block finalization (3-block finality, \~150 ms). A channel only pushes when its data has actually changed — **empty blocks produce no push**.


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