fix: harden persistence checks and export timeout

- Enable draw.io autosave and handle autosave events to update chartXML
- Clear modified state after autosave to avoid beforeunload prompts
- Disable confirmExit in draw.io configuration
- Set modified=false and keepmodified=false URL parameters
- Fix session save condition to also save when only diagram exists

app/[lang]/page.tsx

@@ -33,7 +33,6 @@ export default function Home() {
     const [isDrawioReady, setIsDrawioReady] = useState(false)
     const [isElectron, setIsElectron] = useState(false)
     const [canPersist, setCanPersist] = useState(false)
-    const [canPersistChecked, setCanPersistChecked] = useState(false)
     const [drawioBaseUrl, setDrawioBaseUrl] = useState(
         process.env.NEXT_PUBLIC_DRAWIO_BASE_URL || "https://embed.diagrams.net",
     )
@@ -87,7 +86,6 @@ export default function Home() {
         void (async () => {
             const usable = await isIndexedDBUsable()
             setCanPersist(usable)
-            setCanPersistChecked(true)
         })()
         setIsLoaded(true)
     }, [pathname, router])
@@ -191,7 +189,7 @@ export default function Home() {
                         }`}
                     >
                         <div className="h-full rounded-xl overflow-hidden shadow-soft-lg border border-border/30 relative">
-                            {isLoaded && canPersistChecked && (
+                            {isLoaded && (
                                 <div
                                     className={`h-full w-full ${isDrawioReady ? "" : "invisible absolute inset-0"}`}
                                 >

components/chat-panel.tsx

@@ -581,7 +581,7 @@ export default function ChatPanel({
 
         try {
             const currentSession = sessionManager.currentSession
-            if (currentSession) {
+            if (currentSession && currentSession.messages.length > 0) {
                 // Restore from session manager (IndexedDB)
                 justLoadedSessionRef.current = true
                 syncUIWithSession(currentSession)
@@ -618,7 +618,7 @@ export default function ChatPanel({
         lastSyncedSessionIdRef.current = newSessionId
 
         // Sync UI with new session
-        if (newSession) {
+        if (newSession && newSession.messages.length > 0) {
             justLoadedSessionRef.current = true
             syncUIWithSession(newSession)
         } else if (!newSession) {

contexts/diagram-context.tsx

@@ -57,6 +57,8 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
     const pngResolverRef = useRef<((value: string) => void) | null>(null)
     // Track if we're expecting an export for history (user-initiated)
     const expectHistoryExportRef = useRef<boolean>(false)
+    // Track if diagram has been restored after DrawIO remount (e.g., theme change)
+    const hasDiagramRestoredRef = useRef<boolean>(false)
     // Track latest chartXML for restoration after remount
     const chartXMLRef = useRef<string>("")
 
@@ -78,22 +80,22 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
     }, [chartXML])
 
     // Restore diagram when DrawIO becomes ready after remount (e.g., theme/UI change)
-    // Also restore when chartXML changes while DrawIO is ready (e.g., session loaded after iframe ready)
-    const lastRestoredXmlRef = useRef<string>("")
     useEffect(() => {
-        if (!isDrawioReady || !drawioRef.current) return
-        // Only load if we have a real diagram and it's different from what we already loaded
-        if (
-            isRealDiagram(chartXML) &&
-            chartXML !== lastRestoredXmlRef.current
-        ) {
-            lastRestoredXmlRef.current = chartXML
-            drawioRef.current.load({ xml: chartXML })
-        } else if (!isRealDiagram(chartXML)) {
-            // Reset when diagram is cleared so a future restore can re-load the same XML.
-            lastRestoredXmlRef.current = ""
+        // Reset restore flag when DrawIO is not ready (preparing for next restore cycle)
+        if (!isDrawioReady) {
+            hasDiagramRestoredRef.current = false
+            return
         }
-    }, [isDrawioReady, chartXML])
+        // Only restore once per ready cycle
+        if (hasDiagramRestoredRef.current) return
+        hasDiagramRestoredRef.current = true
+
+        // Restore diagram from ref if we have one
+        const xmlToRestore = chartXMLRef.current
+        if (isRealDiagram(xmlToRestore) && drawioRef.current) {
+            drawioRef.current.load({ xml: xmlToRestore })
+        }
+    }, [isDrawioReady])
 
     // Track if we're expecting an export for file save (stores raw export data)
     const saveResolverRef = useRef<{
@@ -268,11 +270,6 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
 
     const handleDiagramAutoSave = (data: { xml?: string }) => {
         if (!data?.xml) return
-        // Don't overwrite a pending restore - if we have a real diagram in state
-        // but DrawIO isn't ready yet, it means we're waiting to restore
-        if (!isDrawioReady && isRealDiagram(chartXML)) {
-            return
-        }
         setChartXML(data.xml)
     }
 

lib/session-storage.ts

@@ -47,33 +47,6 @@ interface ChatSessionDB extends DBSchema {
 
 // Database singleton
 let dbPromise: Promise<IDBPDatabase<ChatSessionDB>> | null = null
-const resetDBPromise = () => {
-    dbPromise = null
-}
-
-const isClosingError = (error: unknown): boolean => {
-    return (
-        error instanceof DOMException &&
-        error.name === "InvalidStateError" &&
-        /closing/i.test(error.message)
-    )
-}
-
-const withDB = async <T>(
-    action: (db: IDBPDatabase<ChatSessionDB>) => Promise<T>,
-): Promise<T> => {
-    try {
-        const db = await getDB()
-        return await action(db)
-    } catch (error) {
-        if (isClosingError(error)) {
-            resetDBPromise()
-            const db = await getDB()
-            return await action(db)
-        }
-        throw error
-    }
-}
 
 async function getDB(): Promise<IDBPDatabase<ChatSessionDB>> {
     if (!dbPromise) {
@@ -87,23 +60,7 @@ async function getDB(): Promise<IDBPDatabase<ChatSessionDB>> {
                 }
                 // Future migrations: if (oldVersion < 2) { ... }
             },
-            terminated() {
-                resetDBPromise()
-            },
         })
-        dbPromise
-            .then((db) => {
-                db.onversionchange = () => {
-                    db.close()
-                    resetDBPromise()
-                }
-                db.onclose = () => {
-                    resetDBPromise()
-                }
-            })
-            .catch(() => {
-                resetDBPromise()
-            })
     }
     return dbPromise
 }
@@ -119,12 +76,11 @@ export function isIndexedDBAvailable(): boolean {
 }
 
 // Check if IndexedDB is actually usable (not just present).
-// Note: Do NOT close the db here - getDB() returns a shared singleton connection
-// that other code depends on.
 export async function isIndexedDBUsable(): Promise<boolean> {
     if (!isIndexedDBAvailable()) return false
     try {
-        await getDB()
+        const db = await getDB()
+        db.close()
         return true
     } catch {
         return false
@@ -135,29 +91,27 @@ export async function isIndexedDBUsable(): Promise<boolean> {
 export async function getAllSessionMetadata(): Promise<SessionMetadata[]> {
     if (!isIndexedDBAvailable()) return []
     try {
-        return await withDB(async (db) => {
-            const tx = db.transaction(STORE_NAME, "readonly")
-            const index = tx.store.index("by-updated")
-            const metadata: SessionMetadata[] = []
+        const db = await getDB()
+        const tx = db.transaction(STORE_NAME, "readonly")
+        const index = tx.store.index("by-updated")
+        const metadata: SessionMetadata[] = []
 
-            // Use cursor to read only metadata fields (avoids loading full messages/XML)
-            let cursor = await index.openCursor(null, "prev") // newest first
-            while (cursor) {
-                const s = cursor.value
-                metadata.push({
-                    id: s.id,
-                    title: s.title,
-                    createdAt: s.createdAt,
-                    updatedAt: s.updatedAt,
-                    messageCount: s.messages.length,
-                    hasDiagram:
-                        !!s.diagramXml && s.diagramXml.trim().length > 0,
-                    thumbnailDataUrl: s.thumbnailDataUrl,
-                })
-                cursor = await cursor.continue()
-            }
-            return metadata
-        })
+        // Use cursor to read only metadata fields (avoids loading full messages/XML)
+        let cursor = await index.openCursor(null, "prev") // newest first
+        while (cursor) {
+            const s = cursor.value
+            metadata.push({
+                id: s.id,
+                title: s.title,
+                createdAt: s.createdAt,
+                updatedAt: s.updatedAt,
+                messageCount: s.messages.length,
+                hasDiagram: !!s.diagramXml && s.diagramXml.trim().length > 0,
+                thumbnailDataUrl: s.thumbnailDataUrl,
+            })
+            cursor = await cursor.continue()
+        }
+        return metadata
     } catch (error) {
         console.error("Failed to get session metadata:", error)
         return []
@@ -167,9 +121,8 @@ export async function getAllSessionMetadata(): Promise<SessionMetadata[]> {
 export async function getSession(id: string): Promise<ChatSession | null> {
     if (!isIndexedDBAvailable()) return null
     try {
-        return await withDB(async (db) => {
-            return (await db.get(STORE_NAME, id)) || null
-        })
+        const db = await getDB()
+        return (await db.get(STORE_NAME, id)) || null
     } catch (error) {
         console.error("Failed to get session:", error)
         return null
@@ -179,9 +132,8 @@ export async function getSession(id: string): Promise<ChatSession | null> {
 export async function saveSession(session: ChatSession): Promise<boolean> {
     if (!isIndexedDBAvailable()) return false
     try {
-        await withDB(async (db) => {
-            await db.put(STORE_NAME, session)
-        })
+        const db = await getDB()
+        await db.put(STORE_NAME, session)
         return true
     } catch (error) {
         // Handle quota exceeded
@@ -193,9 +145,8 @@ export async function saveSession(session: ChatSession): Promise<boolean> {
             await deleteOldestSession()
             // Retry once
             try {
-                await withDB(async (db) => {
-                    await db.put(STORE_NAME, session)
-                })
+                const db = await getDB()
+                await db.put(STORE_NAME, session)
                 return true
             } catch (retryError) {
                 console.error(
@@ -214,9 +165,8 @@ export async function saveSession(session: ChatSession): Promise<boolean> {
 export async function deleteSession(id: string): Promise<void> {
     if (!isIndexedDBAvailable()) return
     try {
-        await withDB(async (db) => {
-            await db.delete(STORE_NAME, id)
-        })
+        const db = await getDB()
+        await db.delete(STORE_NAME, id)
     } catch (error) {
         console.error("Failed to delete session:", error)
     }
@@ -225,9 +175,8 @@ export async function deleteSession(id: string): Promise<void> {
 export async function getSessionCount(): Promise<number> {
     if (!isIndexedDBAvailable()) return 0
     try {
-        return await withDB(async (db) => {
-            return await db.count(STORE_NAME)
-        })
+        const db = await getDB()
+        return await db.count(STORE_NAME)
     } catch (error) {
         console.error("Failed to get session count:", error)
         return 0
@@ -237,15 +186,14 @@ export async function getSessionCount(): Promise<number> {
 export async function deleteOldestSession(): Promise<void> {
     if (!isIndexedDBAvailable()) return
     try {
-        await withDB(async (db) => {
-            const tx = db.transaction(STORE_NAME, "readwrite")
-            const index = tx.store.index("by-updated")
-            const cursor = await index.openCursor()
-            if (cursor) {
-                await cursor.delete()
-            }
-            await tx.done
-        })
+        const db = await getDB()
+        const tx = db.transaction(STORE_NAME, "readwrite")
+        const index = tx.store.index("by-updated")
+        const cursor = await index.openCursor()
+        if (cursor) {
+            await cursor.delete()
+        }
+        await tx.done
     } catch (error) {
         console.error("Failed to delete oldest session:", error)
     }

lib/system-prompts.ts

@@ -11,7 +11,6 @@ export const DEFAULT_SYSTEM_PROMPT = `
 You are an expert diagram creation assistant specializing in draw.io XML generation.
 Your primary function is chat with user and crafting clear, well-organized visual diagrams through precise XML specifications.
 You can see images that users upload, and you can read the text content extracted from PDF documents they upload.
-ALWAYS respond in the same language as the user's last message.
 
 When you are asked to create a diagram, briefly describe your plan about the layout and structure to avoid object overlapping or edge cross the objects. (2-3 sentences max), then use display_diagram tool to generate the XML.
 After generating or editing a diagram, you don't need to say anything. The user can see the diagram - no need to describe it.