fix: reserve Untitled Project name; rename project will trigger save immidiatly.

src/util/projectNameUtil.ts

@@ -9,6 +9,12 @@ const VALID_PROJECT_NAME_REGEX = /^[a-zA-Z0-9 \-_.()\u00C0-\u024F]+$/;
  */
 const DISALLOWED_CHARS_REGEX = /[^a-zA-Z0-9 \-_.()\u00C0-\u024F]/g;
 
+/**
+ * The reserved project name used for unsaved/new projects.
+ * Users cannot rename a project to this name, and its OPFS folder is wiped on every startup.
+ */
+export const RESERVED_PROJECT_NAME = "Untitled Project";
+
 /**
  * Validate whether a project name contains only allowed characters.
  * Does NOT check for empty string — caller should check that separately.
@@ -19,6 +25,13 @@ export function isValidProjectName(name: string): boolean {
   return VALID_PROJECT_NAME_REGEX.test(name);
 }
 
+/**
+ * Returns true if the given name matches the reserved "Untitled Project" name.
+ */
+export function isReservedProjectName(name: string): boolean {
+  return name.trim() === RESERVED_PROJECT_NAME;
+}
+
 /**
  * Sanitize a project name by replacing disallowed characters with underscores,
  * collapsing consecutive underscores/spaces, and trimming.
@@ -37,7 +50,7 @@ export function sanitizeProjectName(name: string): string {
 
   // If everything was stripped, provide a fallback
   if (sanitized.length === 0) {
-    sanitized = 'Untitled Project';
+    sanitized = RESERVED_PROJECT_NAME;
   }
 
   return sanitized;

src/util/saveUtil.ts

@@ -1,5 +1,6 @@
 import { KGProjectStorage, DuplicateEntryError } from '../core/io/KGProjectStorage';
 import { KGCore } from '../core/KGCore';
+import { RESERVED_PROJECT_NAME } from './projectNameUtil';
 
 /**
  * Save project utility function.
@@ -17,14 +18,27 @@ export const saveProject = async (
   savedProjectName: string,
   setStatus: (status: string) => void,
   onSaveSuccess: (finalName: string) => void,
+  forceOverwrite: boolean = false,
 ): Promise<boolean> => {
   const storage = KGProjectStorage.getInstance();
+
+  // Auto-rename reserved "Untitled Project" to "Untitled Project (1)", "(2)", etc.
+  if (projectName === RESERVED_PROJECT_NAME) {
+    let counter = 1;
+    let autoName = `${RESERVED_PROJECT_NAME} (${counter})`;
+    while (await storage.exists(autoName)) {
+      counter++;
+      autoName = `${RESERVED_PROJECT_NAME} (${counter})`;
+    }
+    projectName = autoName;
+  }
+
   const isRename = savedProjectName !== projectName;
 
   if (isRename) {
-    // Determine the target name, resolving conflicts automatically
+    // Determine the target name; skip conflict resolution when caller already confirmed overwrite
     let targetName = projectName;
-    if (await storage.exists(projectName)) {
+    if (!forceOverwrite && await storage.exists(projectName)) {
       targetName = await storage.resolveUniqueName(projectName);
     }
 
@@ -33,6 +47,7 @@ export const saveProject = async (
         savedProjectName,
         targetName,
         KGCore.instance().getCurrentProject(),
+        forceOverwrite,
       );
 
       const statusMsg =