Got at least one data fetching method working; turns out, we can't use a patched LogicStack to get the data

Vendor/EmbedIO-3.5.2/Sessions/ISessionManager.cs

@@ -0,0 +1,46 @@
+using System.Threading;
+
+namespace EmbedIO.Sessions
+{
+    /// <summary>
+    /// Represents a session manager, which is in charge of managing session objects
+    /// and their association to HTTP contexts.
+    /// </summary>
+    public interface ISessionManager
+    {
+        /// <summary>
+        /// Signals a session manager that the web server is starting.
+        /// </summary>
+        /// <param name="cancellationToken">The cancellation token used to stop the web server.</param>
+        void Start(CancellationToken cancellationToken);
+
+        /// <summary>
+        /// Returns the session associated with an <see cref="IHttpContext"/>.
+        /// If a session ID can be retrieved for the context and stored session data
+        /// are available, the returned <see cref="ISession"/> will contain those data;
+        /// otherwise, a new session is created and its ID is stored in the response
+        /// to be retrieved by subsequent requests.
+        /// </summary>
+        /// <param name="context">The HTTP context.</param>
+        /// <returns>An <see cref="ISession"/> interface.</returns>
+        ISession Create(IHttpContext context);
+
+        /// <summary>
+        /// Deletes the session (if any) associated with the specified context
+        /// and removes the session's ID from the context.
+        /// </summary>
+        /// <param name="context">The HTTP context.</param>
+        /// <param name="id">The unique ID of the session.</param>
+        /// <seealso cref="ISession.Id"/>
+        void Delete(IHttpContext context, string id);
+
+        /// <summary>
+        /// <para>Called by a session proxy when a session has been obtained
+        /// for an <see cref="IHttpContext"/> and the context is closed,
+        /// even if the session was subsequently deleted.</para>
+        /// <para>This method can be used to save session data to a storage medium.</para>
+        /// </summary>
+        /// <param name="context">The <see cref="IHttpContext"/> for which a session was obtained.</param>
+        void OnContextClose(IHttpContext context);
+    }
+}