fix: recover IDB on closing and restore diagram

app/[lang]/page.tsx

@@ -11,16 +11,10 @@ import {
 } from "@/components/ui/resizable"
 import { useDiagram } from "@/contexts/diagram-context"
 import { i18n, type Locale } from "@/lib/i18n/config"
-import { isIndexedDBUsable } from "@/lib/session-storage"
 
 export default function Home() {
-    const {
-        drawioRef,
-        handleDiagramExport,
-        handleDiagramAutoSave,
-        onDrawioLoad,
-        resetDrawioReady,
-    } = useDiagram()
+    const { drawioRef, handleDiagramExport, onDrawioLoad, resetDrawioReady } =
+        useDiagram()
     const router = useRouter()
     const pathname = usePathname()
     // Extract current language from pathname (e.g., "/zh/about" → "zh")
@@ -32,8 +26,6 @@ export default function Home() {
     const [isLoaded, setIsLoaded] = useState(false)
     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",
     )
@@ -84,11 +76,6 @@ export default function Home() {
             setDrawioBaseUrl(`${window.location.origin}/drawio/index.html`)
         }
 
-        void (async () => {
-            const usable = await isIndexedDBUsable()
-            setCanPersist(usable)
-            setCanPersistChecked(true)
-        })()
         setIsLoaded(true)
     }, [pathname, router])
 
@@ -97,17 +84,6 @@ export default function Home() {
         onDrawioLoad()
     }, [onDrawioLoad])
 
-    const handleDrawioAutoSave = useCallback(
-        (data: { xml?: string }) => {
-            handleDiagramAutoSave(data)
-            // Only suppress modified state when persistence is available
-            if (canPersist) {
-                drawioRef.current?.status({ message: "", modified: false })
-            }
-        },
-        [canPersist, drawioRef, handleDiagramAutoSave],
-    )
-
     const handleDarkModeChange = () => {
         const newValue = !darkMode
         setDarkMode(newValue)
@@ -191,32 +167,20 @@ 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 ${isDrawioReady ? "" : "invisible absolute inset-0"}`}
                                 >
                                     <DrawIoEmbed
                                         key={`${drawioUi}-${darkMode}-${currentLang}-${isElectron}`}
                                         ref={drawioRef}
-                                        autosave
-                                        onAutoSave={handleDrawioAutoSave}
                                         onExport={handleDiagramExport}
                                         onLoad={handleDrawioLoad}
                                         baseUrl={drawioBaseUrl}
-                                        configuration={
-                                            canPersist
-                                                ? { confirmExit: false }
-                                                : undefined
-                                        }
                                         urlParameters={{
                                             ui: drawioUi,
                                             spin: false,
                                             libraries: false,
-                                            // Disable modified tracking only when persistence is available
-                                            ...(canPersist && {
-                                                modified: false,
-                                                keepmodified: false,
-                                            }),
                                             saveAndExit: false,
                                             noSaveBtn: true,
                                             noExitBtn: true,

components/chat-panel.tsx

@@ -137,22 +137,26 @@ export default function ChatPanel({
     const onFetchChart = (saveToHistory = true) => {
         return Promise.race([
             new Promise<string>((resolve) => {
-                resolverRef.current = resolve
+                if (resolverRef && "current" in resolverRef) {
+                    resolverRef.current = resolve
+                }
                 if (saveToHistory) {
                     onExport()
                 } else {
                     handleExportWithoutHistory()
                 }
             }),
-            new Promise<string>((_, reject) => {
-                const currentResolver = resolverRef.current
-                setTimeout(() => {
-                    if (resolverRef.current === currentResolver) {
-                        resolverRef.current = null
-                    }
-                    reject(new Error("Chart export timed out after 10 seconds"))
-                }, 10000)
-            }),
+            new Promise<string>((_, reject) =>
+                setTimeout(
+                    () =>
+                        reject(
+                            new Error(
+                                "Chart export timed out after 10 seconds",
+                            ),
+                        ),
+                    10000,
+                ),
+            ),
         ])
     }
 
@@ -581,7 +585,7 @@ export default function ChatPanel({
 
         try {
             const currentSession = sessionManager.currentSession
-            if (currentSession && currentSession.messages.length > 0) {
+            if (currentSession) {
                 // Restore from session manager (IndexedDB)
                 justLoadedSessionRef.current = true
                 syncUIWithSession(currentSession)
@@ -618,7 +622,7 @@ export default function ChatPanel({
         lastSyncedSessionIdRef.current = newSessionId
 
         // Sync UI with new session
-        if (newSession && newSession.messages.length > 0) {
+        if (newSession) {
             justLoadedSessionRef.current = true
             syncUIWithSession(newSession)
         } else if (!newSession) {
@@ -673,7 +677,7 @@ export default function ChatPanel({
         // Debounce: save after 1 second of no changes
         localStorageDebounceRef.current = setTimeout(async () => {
             try {
-                if (messages.length > 0 || hasDiagramNow) {
+                if (messages.length > 0) {
                     const sessionData = await buildSessionData({
                         // Only capture thumbnail if there was a diagram AND this isn't a no-diagram session
                         withThumbnail: hasDiagramNow && !isNodiagramSession,
@@ -695,7 +699,6 @@ export default function ChatPanel({
             }
         }
     }, [
-        chartXML,
         messages,
         status,
         sessionIsAvailable,
@@ -726,8 +729,7 @@ export default function ChatPanel({
         const handleVisibilityChange = async () => {
             if (
                 document.visibilityState === "hidden" &&
-                (messagesRef.current.length > 0 ||
-                    isRealDiagram(chartXMLRef.current))
+                messagesRef.current.length > 0
             ) {
                 try {
                     // Attempt to save session - browser may not wait for completion

contexts/diagram-context.tsx

@@ -20,10 +20,9 @@ interface DiagramContextType {
     loadDiagram: (chart: string, skipValidation?: boolean) => string | null
     handleExport: () => void
     handleExportWithoutHistory: () => void
-    resolverRef: React.MutableRefObject<((value: string) => void) | null>
-    drawioRef: React.MutableRefObject<DrawIoEmbedRef | null>
+    resolverRef: React.Ref<((value: string) => void) | null>
+    drawioRef: React.Ref<DrawIoEmbedRef | null>
     handleDiagramExport: (data: any) => void
-    handleDiagramAutoSave: (data: { xml?: string }) => void
     clearDiagram: () => void
     saveDiagramToFile: (
         filename: string,
@@ -57,6 +56,8 @@ 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>("")
 
@@ -78,19 +79,22 @@ 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 })
+        // 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<{
@@ -263,11 +267,6 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
         }
     }
 
-    const handleDiagramAutoSave = (data: { xml?: string }) => {
-        if (!data?.xml) return
-        setChartXML(data.xml)
-    }
-
     const clearDiagram = () => {
         const emptyDiagram = `<mxfile><diagram name="Page-1" id="page-1"><mxGraphModel><root><mxCell id="0"/><mxCell id="1" parent="0"/></root></mxGraphModel></diagram></mxfile>`
         // Skip validation for trusted internal template (loadDiagram also sets chartXML)
@@ -392,7 +391,6 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
                 resolverRef,
                 drawioRef,
                 handleDiagramExport,
-                handleDiagramAutoSave,
                 clearDiagram,
                 saveDiagramToFile,
                 getThumbnailSvg,

lib/session-storage.ts

@@ -47,6 +47,33 @@ 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) {
@@ -60,7 +87,23 @@ 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
 }
@@ -75,44 +118,33 @@ 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()
-        return true
-    } catch {
-        return false
-    }
-}
-
 // CRUD Operations
 export async function getAllSessionMetadata(): Promise<SessionMetadata[]> {
     if (!isIndexedDBAvailable()) return []
     try {
-        const db = await getDB()
-        const tx = db.transaction(STORE_NAME, "readonly")
-        const index = tx.store.index("by-updated")
-        const metadata: SessionMetadata[] = []
+        return await withDB(async (db) => {
+            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 []
@@ -122,8 +154,9 @@ export async function getAllSessionMetadata(): Promise<SessionMetadata[]> {
 export async function getSession(id: string): Promise<ChatSession | null> {
     if (!isIndexedDBAvailable()) return null
     try {
-        const db = await getDB()
-        return (await db.get(STORE_NAME, id)) || null
+        return await withDB(async (db) => {
+            return (await db.get(STORE_NAME, id)) || null
+        })
     } catch (error) {
         console.error("Failed to get session:", error)
         return null
@@ -133,8 +166,9 @@ export async function getSession(id: string): Promise<ChatSession | null> {
 export async function saveSession(session: ChatSession): Promise<boolean> {
     if (!isIndexedDBAvailable()) return false
     try {
-        const db = await getDB()
-        await db.put(STORE_NAME, session)
+        await withDB(async (db) => {
+            await db.put(STORE_NAME, session)
+        })
         return true
     } catch (error) {
         // Handle quota exceeded
@@ -146,8 +180,9 @@ export async function saveSession(session: ChatSession): Promise<boolean> {
             await deleteOldestSession()
             // Retry once
             try {
-                const db = await getDB()
-                await db.put(STORE_NAME, session)
+                await withDB(async (db) => {
+                    await db.put(STORE_NAME, session)
+                })
                 return true
             } catch (retryError) {
                 console.error(
@@ -166,8 +201,9 @@ export async function saveSession(session: ChatSession): Promise<boolean> {
 export async function deleteSession(id: string): Promise<void> {
     if (!isIndexedDBAvailable()) return
     try {
-        const db = await getDB()
-        await db.delete(STORE_NAME, id)
+        await withDB(async (db) => {
+            await db.delete(STORE_NAME, id)
+        })
     } catch (error) {
         console.error("Failed to delete session:", error)
     }
@@ -176,8 +212,9 @@ export async function deleteSession(id: string): Promise<void> {
 export async function getSessionCount(): Promise<number> {
     if (!isIndexedDBAvailable()) return 0
     try {
-        const db = await getDB()
-        return await db.count(STORE_NAME)
+        return await withDB(async (db) => {
+            return await db.count(STORE_NAME)
+        })
     } catch (error) {
         console.error("Failed to get session count:", error)
         return 0
@@ -187,14 +224,15 @@ export async function getSessionCount(): Promise<number> {
 export async function deleteOldestSession(): Promise<void> {
     if (!isIndexedDBAvailable()) return
     try {
-        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
+        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
+        })
     } catch (error) {
         console.error("Failed to delete oldest session:", error)
     }