gaoxy_websock_adapter

diff --git a/lib/websock_adapter.ex b/lib/websock_adapter.ex
index de367e6d0b242f5333ab69a802ef7987c5cd293e..71123c83e6a2527200a4de3d0b6f5672dfafd187 100644
--- a/lib/websock_adapter.ex
+++ b/lib/websock_adapter.ex
@@ -72,6 +72,7 @@ defmodule WebSockAdapter do
     Plug.Conn.upgrade_adapter(conn, :websocket, tuple)
   end
 
+  defp tuple_for(Gaoxy.PlugAdapter, websock, state, opts), do: {websock, state, opts}
   defp tuple_for(Bandit.Adapter, websock, state, opts), do: {websock, state, opts}
   # Support for adapters as specified prior to Bandit 1.4
   defp tuple_for(Bandit.HTTP1.Adapter, websock, state, opts), do: {websock, state, opts}
diff --git a/lib/websock_adapter/upgrade_validation.ex b/lib/websock_adapter/upgrade_validation.ex
index 313310dff13ae0e321286027697753190db56cff..732c83e3d7f704dbb73e7301178dc836bd40b4df 100644
--- a/lib/websock_adapter/upgrade_validation.ex
+++ b/lib/websock_adapter/upgrade_validation.ex
@@ -24,6 +24,13 @@ defmodule WebSockAdapter.UpgradeValidation do
   `{:error, reason}` if not
   """
   @spec validate_upgrade(Plug.Conn.t()) :: :ok | {:error, String.t()}
+  def validate_upgrade(%Plug.Conn{
+        adapter: {Gaoxy.PlugAdapter, %{request: %{version: version} = request}}
+      })
+      when version in [:"HTTP/2", :"HTTP/3"] do
+    validate_gaoxy_extended(request)
+  end
+
   def validate_upgrade(conn) do
     case Plug.Conn.get_http_protocol(conn) do
       :"HTTP/1.1" -> validate_upgrade_http1(conn)
@@ -32,6 +39,17 @@ defmodule WebSockAdapter.UpgradeValidation do
     end
   end
 
+  # Phoenix may see a temporary GET view. Gaoxy's immutable native metadata
+  # supplies the RFC 8441/9220 method/protocol without a reverse dependency.
+  defp validate_gaoxy_extended(%{method: "CONNECT", protocol: "websocket", headers: headers})
+       when is_list(headers) do
+    if for({"sec-websocket-version", value} <- headers, do: value) == ["13"],
+      do: :ok,
+      else: {:error, "'sec-websocket-version' header must equal '13'"}
+  end
+
+  defp validate_gaoxy_extended(_), do: {:error, "invalid native extended WebSocket request"}
+
   @doc """
   Raising variant of `validate_upgrade/1`.
 
diff --git a/test/gaoxy_dispatch_test.exs b/test/gaoxy_dispatch_test.exs
new file mode 100644
index 0000000000000000000000000000000000000000..6957c6b6ed6796b827dcf3cb85a0469d1def8c1b
--- /dev/null
+++ b/test/gaoxy_dispatch_test.exs
@@ -0,0 +1,78 @@
+# This isolated dependency test supplies the consumer's public adapter contract.
+defmodule Gaoxy.PlugAdapter do
+  def upgrade(:payload, :websocket, {handler, state, options}),
+    do: {:ok, {:native, handler, state, options}}
+
+  def upgrade(%{request: _} = payload, :websocket, {handler, state, options}),
+    do: {:ok, {:native, payload, handler, state, options}}
+
+  def get_http_protocol(%{request: %{version: version}}), do: version
+end
+
+defmodule WebSockAdapter.GaoxyDispatchTest do
+  use ExUnit.Case, async: true
+
+  test "dispatches the native Gaoxy adapter tuple" do
+    conn = %Plug.Conn{adapter: {Gaoxy.PlugAdapter, :payload}}
+    upgraded = WebSockAdapter.upgrade(conn, MyWebSock, :state, early_validate_upgrade: false)
+    assert upgraded.state == :upgraded
+    assert {Gaoxy.PlugAdapter, {:native, MyWebSock, :state, options}} = upgraded.adapter
+    assert options[:max_frame_size] == 10_000_000
+  end
+
+  test "Gaoxy H2 and H3 use immutable CONNECT metadata while Phoenix sees GET" do
+    for version <- [:"HTTP/2", :"HTTP/3"] do
+      request = %{
+        method: "CONNECT",
+        protocol: "websocket",
+        version: version,
+        headers: [{"sec-websocket-version", "13"}]
+      }
+
+      conn = %Plug.Conn{
+        method: "GET",
+        req_headers: request.headers,
+        adapter: {Gaoxy.PlugAdapter, %{request: request}}
+      }
+
+      result = WebSockAdapter.upgrade(conn, MyWebSock, :state, [])
+      assert result.state == :upgraded
+
+      assert {Gaoxy.PlugAdapter, {:native, %{request: ^request}, MyWebSock, :state, _}} =
+               result.adapter
+    end
+  end
+
+  test "apparent GET cannot replace missing or invalid native extended metadata" do
+    for request <- [
+          %{
+            method: "GET",
+            protocol: "websocket",
+            version: :"HTTP/2",
+            headers: [{"sec-websocket-version", "13"}]
+          },
+          %{
+            method: "CONNECT",
+            protocol: "other",
+            version: :"HTTP/3",
+            headers: [{"sec-websocket-version", "13"}]
+          },
+          %{
+            method: "CONNECT",
+            protocol: "websocket",
+            version: :"HTTP/3",
+            headers: [{"sec-websocket-version", "12"}]
+          }
+        ] do
+      conn = %Plug.Conn{
+        method: "GET",
+        req_headers: [{"sec-websocket-version", "13"}],
+        adapter: {Gaoxy.PlugAdapter, %{request: request}}
+      }
+
+      assert_raise WebSockAdapter.UpgradeError, fn ->
+        WebSockAdapter.upgrade(conn, MyWebSock, :state, [])
+      end
+    end
+  end
+end