Proper caching for loaded WI

- Implement StructurecCloneMap, which is a map that provides structured clones on both get and set
- Don't delete WI cache on save, but update the cache
- Ensure that cache is updated immediately, so any future get will load the new saved data already
- Still be consistent with clones, so requested cache data that wasn't saved isn't taken into account

public/scripts/util/StructuredCloneMap.js

@@ -0,0 +1,36 @@
+/**
+ * A specialized Map class that provides consistent data storage by performing deep cloning of values.
+ *
+ * @template K, V
+ * @extends Map<K, V>
+ */
+export class StructuredCloneMap extends Map {
+    /**
+     * Adds a new element with a specified key and value to the Map. If an element with the same key already exists, the element will be updated.
+     *
+     * The set value will always be a deep clone of the provided value to provide consistent data storage.
+     *
+     * @param {K} key - The key to set
+     * @param {V} value - The value to set
+     * @returns {this} The updated map
+     */
+    set(key, value) {
+        const clonedValue = structuredClone(value);
+        super.set(key, clonedValue);
+        return this;
+    }
+
+    /**
+     * Returns a specified element from the Map object.
+     * If the value that is associated to the provided key is an object, then you will get a reference to that object and any change made to that object will effectively modify it inside the Map.
+     *
+     * The returned value will always be a deep clone of the cached value.
+     *
+     * @param {K} key - The key to get the value for
+     * @returns {V | undefined} Returns the element associated with the specified key. If no element is associated with the specified key, undefined is returned.
+     */
+    get(key) {
+        const value = super.get(key);
+        return structuredClone(value);
+    }
+}

public/scripts/world-info.js

@@ -16,6 +16,7 @@ import { SlashCommandEnumValue, enumTypes } from './slash-commands/SlashCommandE
 import { commonEnumProviders, enumIcons } from './slash-commands/SlashCommandCommonEnumsProvider.js';
 import { SlashCommandClosure } from './slash-commands/SlashCommandClosure.js';
 import { callGenericPopup, Popup, POPUP_TYPE } from './popup.js';
+import { StructuredCloneMap } from './util/StructuredCloneMap.js';
 
 export {
     world_info,
@@ -746,7 +747,8 @@ export const wi_anchor_position = {
     after: 1,
 };
 
-const worldInfoCache = new Map();
+/** @type {StructuredCloneMap<string,object>} */
+const worldInfoCache = new StructuredCloneMap();
 
 /**
  * Gets the world info based on chat messages.
@@ -3280,7 +3282,8 @@ async function saveWorldInfo(name, data, immediately) {
         return;
     }
 
-    worldInfoCache.delete(name);
+    // Update cache immediately, so any future call can pull from this
+    worldInfoCache.set(name, structuredClone(data));
 
     if (immediately) {
         return await _save(name, data);