Added the system from trail

Runtime/EncounterLink.cs

@@ -0,0 +1,33 @@
+using System;
+
+namespace Jovian.EncounterSystem {
+    /// <summary>
+    /// Cross-table reference to an <see cref="IEncounter"/>. Stores the owning
+    /// <see cref="EncounterTable"/> asset and the target encounter's <see cref="EncounterDefinition.internalId"/>.
+    /// Rename-safe because the stored key is a GUID.
+    /// </summary>
+    [Serializable]
+    public struct EncounterLink {
+        /// <summary>The table that owns the linked encounter.</summary>
+        public EncounterTable table;
+
+        /// <summary>The target encounter's stable GUID (<see cref="EncounterDefinition.internalId"/>).</summary>
+        public string internalId;
+
+        /// <summary>Look up the referenced encounter, or <c>null</c> if the table is missing or the id
+        /// no longer exists in it.</summary>
+        public IEncounter Resolve() {
+            if(table == null || table.encounters == null || string.IsNullOrEmpty(internalId)) {
+                return null;
+            }
+
+            foreach(var encounter in table.encounters) {
+                if(encounter?.EncounterDefinition?.internalId == internalId) {
+                    return encounter;
+                }
+            }
+
+            return null;
+        }
+    }
+}