# `Bourse.WS.Subscription.MethodSubscription`
[🔗](https://github.com/ZenHive/bourse/blob/main/lib/bourse/ws/subscription/method_subscription.ex#L1)

Hyperliquid-style subscribe frame.

    %{"method" => "subscribe", "subscription" => %{"type" => "allMids"}}

Accepts two caller conventions per channel list (same dual-shape contract as
`MethodParams` / `EventSubscribe`):

1. **Plain strings** — each string becomes the nested subscription's `"type"`.
   Hyperliquid accepts one subscription object per frame; when multiple
   strings are supplied the first is used (matches prior single-type behavior).

       MethodSubscription.subscribe(["allMids"], %{})
       # => %{"method" => "subscribe", "subscription" => %{"type" => "allMids"}}

2. **Single pre-shaped map** — used as the `subscription` object directly
   (e.g. `%{"type" => "l2Book", "coin" => "BTC"}`). Passing a map into the
   string branch previously double-wrapped to
   `%{"type" => %{"type" => "allMids"}}` and the venue rejected the frame.

       MethodSubscription.subscribe([%{"type" => "allMids"}], %{})
       # => %{"method" => "subscribe", "subscription" => %{"type" => "allMids"}}

Multiple maps per call return `{:error, :multiple_maps_not_supported}`;
lists that mix maps and strings return `{:error, :mixed_channel_types}`.

Config keys: `:op_field` (default `"method"`), `:args_field`
(default `"subscription"`).

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*Consult [api-reference.md](api-reference.md) for complete listing*