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/ISession.cs

@@ -0,0 +1,112 @@
+using System;
+using System.Collections.Generic;
+
+namespace EmbedIO.Sessions
+{
+    /// <summary>
+    /// Represents a session.
+    /// </summary>
+    public interface ISession
+    {
+        /// <summary>
+        /// A unique identifier for the session.
+        /// </summary>
+        /// <value>The unique identifier for this session.</value>
+        /// <seealso cref="Session.IdComparison"/>
+        /// <seealso cref="Session.IdComparer"/>
+        string Id { get; }
+
+        /// <summary>
+        /// Gets the time interval, starting from <see cref="LastActivity"/>,
+        /// after which the session expires.
+        /// </summary>
+        /// <value> The expiration time.</value>
+        TimeSpan Duration { get; }
+
+        /// <summary>
+        /// Gets the UTC date and time of last activity on the session.
+        /// </summary>
+        /// <value>
+        /// The UTC date and time of last activity on the session.
+        /// </value>
+        DateTime LastActivity { get; }
+
+        /// <summary>
+        /// Gets the number of key/value pairs contained in a session.
+        /// </summary>
+        /// <value>
+        /// The number of key/value pairs contained in the object that implements <see cref="ISession"/>.
+        /// </value>
+        int Count { get; }
+
+        /// <summary>
+        /// Gets a value that indicates whether a session is empty.
+        /// </summary>
+        /// <value>
+        /// <see langword="true"/> if the object that implements <see cref="ISession"/> is empty,
+        /// i.e. contains no key / value pairs; otherwise, <see langword="false"/>.
+        /// </value>
+        bool IsEmpty { get; }
+
+        /// <summary>
+        /// <para>Gets or sets the value associated with the specified key.</para>
+        /// <para>Note that a session does not store null values; therefore, setting this property to <see langword="null"/>
+        /// has the same effect as removing <paramref name="key"/> from the dictionary.</para>
+        /// </summary>
+        /// <value>
+        /// The value associated with the specified key, if <paramref name="key"/>
+        /// is found in the dictionary; otherwise, <see langword="null"/>.
+        /// </value>
+        /// <param name="key">The key of the value to get or set.</param>
+        /// <exception cref="ArgumentNullException"><paramref name="key"/> is <see langword="null"/>.</exception>
+        object this[string key] { get; set; }
+
+        /// <summary>
+        /// Removes all keys and values from a session.
+        /// </summary>
+        void Clear();
+
+        /// <summary>
+        /// Determines whether a session contains an element with the specified key.
+        /// </summary>
+        /// <param name="key">The key to locate in the object that implements <see cref="ISession"/>.</param>
+        /// <returns>
+        /// <see langword="true"/> if the object that implements <see cref="ISession"/> contains an element with the key;
+        /// otherwise, <see langword="false"/> .
+        /// </returns>
+        /// <exception cref="ArgumentNullException"><paramref name="key"/> is <see langword="null"/>.</exception>
+        bool ContainsKey(string key);
+
+        /// <summary>
+        /// Gets the value associated with the specified key.
+        /// </summary>
+        /// <param name="key">The key whose value to get.</param>
+        /// <param name="value">When this method returns, the value associated with the specified <paramref name="key"/>,
+        /// if the key is found; otherwise, <see langword="null"/>. This parameter is passed uninitialized.</param>
+        /// <returns><see langword="true"/> if the object that implements <see cref="ISession"/>
+        /// contains an element with the specified key; otherwise, <see langword="false"/>.</returns>
+        /// <exception cref="ArgumentNullException"><paramref name="key"/> is <see langword="null"/>.</exception>
+        bool TryGetValue(string key, out object value);
+
+        /// <summary>
+        /// Attempts to remove and return the value that has the specified key from a session.
+        /// </summary>
+        /// <param name="key">The key of the element to remove and return.</param>
+        /// <param name="value">When this method returns, the value removed from the object that implements <see cref="ISession"/>,
+        /// if the key is found; otherwise, <see langword="null"/>. This parameter is passed uninitialized.</param>
+        /// <returns><see langword="true"/> if the value was removed successfully; otherwise, <see langword="false"/>.</returns>
+        /// <exception cref="ArgumentNullException"><paramref name="key"/> is <see langword="null"/>.</exception>
+        bool TryRemove(string key, out object value);
+
+        /// <summary>
+        /// Takes and returns a snapshot of the contents of a session at the time of calling.
+        /// </summary>
+        /// <returns>An <see cref="IReadOnlyList{T}">IReadOnlyList&lt;KeyValuePair&lt;string,object&gt;&gt;</see> interface
+        /// containing an immutable copy of the session data as it was at the time of calling this method.</returns>
+        /// <remarks>
+        /// <para>The objects contained in the session data are copied by reference, not cloned; therefore
+        /// you should be aware that their state may change even after the snapshot is taken.</para>
+        /// </remarks>
+        IReadOnlyList<KeyValuePair<string, object>> TakeSnapshot();
+    }
+}