feat: show success toast after diagram download completes

- Add optional successMessage parameter to saveDiagramToFile()
- Show toast after file download is initiated, not when dialog opens
- Add i18n strings for success message (en/ja/zh)

This is the correct implementation for issue #479 - showing feedback
after the actual save completes rather than when the save dialog opens.

app/[lang]/page.tsx

@@ -17,8 +17,14 @@ const drawioBaseUrl =
     process.env.NEXT_PUBLIC_DRAWIO_BASE_URL || "https://embed.diagrams.net"
 
 export default function Home() {
-    const { drawioRef, handleDiagramExport, onDrawioLoad, resetDrawioReady } =
-        useDiagram()
+    const {
+        drawioRef,
+        handleDiagramExport,
+        onDrawioLoad,
+        resetDrawioReady,
+        showSaveDialog,
+        setShowSaveDialog,
+    } = useDiagram()
     const router = useRouter()
     const pathname = usePathname()
     // Extract current language from pathname (e.g., "/zh/about" → "zh")
@@ -32,8 +38,30 @@ export default function Home() {
     const [closeProtection, setCloseProtection] = useState(false)
 
     const chatPanelRef = useRef<ImperativePanelHandle>(null)
+    const isSavingRef = useRef(false)
+    const mouseOverDrawioRef = useRef(false)
     const isMobileRef = useRef(false)
 
+    // Reset saving flag when dialog closes (with delay to ignore lingering save events from draw.io)
+    useEffect(() => {
+        if (!showSaveDialog) {
+            const timeout = setTimeout(() => {
+                isSavingRef.current = false
+            }, 1000)
+            return () => clearTimeout(timeout)
+        }
+    }, [showSaveDialog])
+
+    // Handle save from draw.io's built-in save button
+    // Note: draw.io sends save events for various reasons (focus changes, etc.)
+    // We use mouse position to determine if the user is interacting with draw.io
+    const handleDrawioSave = useCallback(() => {
+        if (!mouseOverDrawioRef.current) return
+        if (isSavingRef.current) return
+        isSavingRef.current = true
+        setShowSaveDialog(true)
+    }, [setShowSaveDialog])
+
     // Load preferences from localStorage after mount
     useEffect(() => {
         // Restore saved locale and redirect if needed
@@ -176,6 +204,12 @@ export default function Home() {
                         className={`h-full relative ${
                             isMobile ? "p-1" : "p-2"
                         }`}
+                        onMouseEnter={() => {
+                            mouseOverDrawioRef.current = true
+                        }}
+                        onMouseLeave={() => {
+                            mouseOverDrawioRef.current = false
+                        }}
                     >
                         <div className="h-full rounded-xl overflow-hidden shadow-soft-lg border border-border/30 relative">
                             {isLoaded && (
@@ -187,13 +221,13 @@ export default function Home() {
                                         ref={drawioRef}
                                         onExport={handleDiagramExport}
                                         onLoad={handleDrawioLoad}
+                                        onSave={handleDrawioSave}
                                         baseUrl={drawioBaseUrl}
                                         urlParameters={{
                                             ui: drawioUi,
                                             spin: false,
                                             libraries: false,
                                             saveAndExit: false,
-                                            noSaveBtn: true,
                                             noExitBtn: true,
                                             dark: darkMode,
                                             lang: currentLang,

package.json

@@ -1,6 +1,6 @@
 {
     "name": "next-ai-draw-io",
-    "version": "0.4.9",
+    "version": "0.4.8",
     "license": "Apache-2.0",
     "private": true,
     "main": "dist-electron/main/index.js",