Added the system from trail

Runtime/DialogLineRef.cs

@@ -0,0 +1,36 @@
+using System;
+using UnityEngine;
+
+namespace Jovian.EncounterSystem {
+    /// <summary>
+    /// Reference to a dialog line. Looks up <see cref="id"/> inside <see cref="library"/> when both
+    /// are set; otherwise falls back to <see cref="inlineText"/>. This lets designers prototype
+    /// one-off lines inline and promote common ones to the shared library later without changing
+    /// the field's type.
+    /// </summary>
+    [Serializable]
+    public struct DialogLineRef {
+        /// <summary>Shared library to resolve <see cref="id"/> against. Optional.</summary>
+        public DialogLineLibrary library;
+
+        /// <summary>Line id inside <see cref="library"/>. Ignored if <see cref="library"/> is null.</summary>
+        public string id;
+
+        /// <summary>Fallback text used when the library reference is missing or fails to resolve.
+        /// Authored directly in the inspector for one-off lines.</summary>
+        [TextArea(2, 6)]
+        public string inlineText;
+
+        /// <summary>Resolve to final text. Returns <see cref="inlineText"/> if no library reference
+        /// resolves, or <c>null</c> if both paths yield nothing.</summary>
+        public string Resolve() {
+            if(library != null && !string.IsNullOrEmpty(id)) {
+                var text = library.Resolve(id);
+                if(!string.IsNullOrEmpty(text)) {
+                    return text;
+                }
+            }
+            return inlineText;
+        }
+    }
+}