inheritance of character from parent using extends key

Author: ShreyGanatra

agent/src/index.ts

@@ -144,6 +144,61 @@ function tryLoadFile(filePath: string): string | null {
         return null;
     }
 }
+function mergeCharacters(base: Character, child: Character): Character {
+    const mergeObjects = (baseObj: any, childObj: any) => {
+        const result: any = {};
+        const keys = new Set([...Object.keys(baseObj || {}), ...Object.keys(childObj || {})]);
+        keys.forEach(key => {
+            if (typeof baseObj[key] === 'object' && typeof childObj[key] === 'object' && !Array.isArray(baseObj[key]) && !Array.isArray(childObj[key])) {
+                result[key] = mergeObjects(baseObj[key], childObj[key]);
+            } else if (Array.isArray(baseObj[key]) || Array.isArray(childObj[key])) {
+                result[key] = [...(baseObj[key] || []), ...(childObj[key] || [])];
+            } else {
+                result[key] = childObj[key] !== undefined ? childObj[key] : baseObj[key];
+            }
+        });
+        return result;
+    };
+    return mergeObjects(base, child);
+}
+async function loadCharacter(filePath: string): Promise<Character> {
+    const content = tryLoadFile(filePath);
+    if (!content) {
+        throw new Error(`Character file not found: ${filePath}`);
+    }
+    let character = JSON.parse(content);
+    validateCharacterConfig(character);
+
+     // .id isn't really valid
+     const characterId = character.id || character.name;
+     const characterPrefix = `CHARACTER.${characterId.toUpperCase().replace(/ /g, "_")}.`;
+     const characterSettings = Object.entries(process.env)
+         .filter(([key]) => key.startsWith(characterPrefix))
+         .reduce((settings, [key, value]) => {
+             const settingKey = key.slice(characterPrefix.length);
+             return { ...settings, [settingKey]: value };
+         }, {});
+     if (Object.keys(characterSettings).length > 0) {
+         character.settings = character.settings || {};
+         character.settings.secrets = {
+             ...characterSettings,
+             ...character.settings.secrets,
+         };
+     }
+     // Handle plugins
+     character.plugins = await handlePluginImporting(
+        character.plugins
+    );
+    if (character.extends) {
+        elizaLogger.info(`Merging  ${character.name} character with parent characters`);
+        for (const extendPath of character.extends) {
+            const baseCharacter = await loadCharacter(path.resolve(path.dirname(filePath), extendPath));
+            character = mergeCharacters(baseCharacter, character);
+            elizaLogger.info(`Merged ${character.name} with ${baseCharacter.name}`);
+        }
+    }
+    return character;
+}
 
 export async function loadCharacters(
     charactersArg: string
@@ -207,32 +262,7 @@ export async function loadCharacters(
             }
 
             try {
-                const character = JSON.parse(content);
-                validateCharacterConfig(character);
-
-                // .id isn't really valid
-                const characterId = character.id || character.name;
-                const characterPrefix = `CHARACTER.${characterId.toUpperCase().replace(/ /g, "_")}.`;
-
-                const characterSettings = Object.entries(process.env)
-                    .filter(([key]) => key.startsWith(characterPrefix))
-                    .reduce((settings, [key, value]) => {
-                        const settingKey = key.slice(characterPrefix.length);
-                        return { ...settings, [settingKey]: value };
-                    }, {});
-
-                if (Object.keys(characterSettings).length > 0) {
-                    character.settings = character.settings || {};
-                    character.settings.secrets = {
-                        ...characterSettings,
-                        ...character.settings.secrets,
-                    };
-                }
-
-                // Handle plugins
-                character.plugins = await handlePluginImporting(
-                    character.plugins
-                );
+                const character: Character = await loadCharacter(resolvedPath);
 
                 loadedCharacters.push(character);
                 elizaLogger.info(

packages/core/src/defaultCharacter.ts

@@ -527,4 +527,5 @@ export const defaultCharacter: Character = {
         "meticulous",
         "provocative",
     ],
+    extends: [],
 };

packages/core/src/environment.ts

@@ -135,6 +135,7 @@ export const CharacterSchema = z.object({
             prompt: z.string().optional(),
         })
         .optional(),
+    extends: z.array(z.string()).optional(),
 });
 
 // Type inference

packages/core/src/types.ts

@@ -871,6 +871,8 @@ export type Character = {
     nft?: {
         prompt: string;
     };
+    /**Optinal Parent characters to inherit information from */
+    extends?: string[];
 };
 
 /**