# Heatmap

L2 order book heatmap reads.

`client.Heatmap` reads historical L2 heatmap buckets and streams live buckets. It is an analytics surface, not an authoritative local order book.

```go
symbol := "BTC-USDT"
history, err := client.Heatmap.Get(
	ctx, &symbol, nil,
	"1s", 50, 100, "close",
	nil, nil, nil,
)
if err != nil { log.Fatal(err) }
fmt.Println(history.Raw)
```

Pass `symbol` or `symbolID`. `fromTsSec` and `start`/`end` select the window. Interval, depth, and quantity-mode labels are validated.

```go
sub, err := client.Heatmap.SubscribeLive(ctx, &symbol, nil, "1s")
if err != nil { log.Fatal(err) }
defer sub.Close()
for bucket := range sub.Messages() {
	fmt.Println(bucket.Raw)
	break
}
```

The stream is public. Symbol-name resolution depends on catalog hydration; call `WaitForCatalogs` first or pass `symbolID`.

For executable levels and sequence recovery use [Order book](https://testnet.polyester.com/docs/sdk/go/reference/order-book).