fix: prevent flash of example panel and animations on page refresh

- Add isRestored state to track when localStorage restoration completes - Show example panel only after confirming no saved messages exist - Skip message animations for restored messages - Default tool calls and reasoning blocks to collapsed for restored messages
fix: hide Draw.io loading flash with placeholder (#481 )
2026-01-02 22:32:27 +08:00 · 2026-01-01 15:31:22 +09:00 · 2026-01-01 15:20:00 +09:00 · 2026-01-01 14:47:39 +09:00
5 changed files with 126 additions and 32 deletions
--- a/app/[lang]/page.tsx
+++ b/app/[lang]/page.tsx
@@ -35,6 +35,7 @@ export default function Home() {
    const [drawioUi, setDrawioUi] = useState<"min" | "sketch">("min")
    const [darkMode, setDarkMode] = useState(false)
    const [isLoaded, setIsLoaded] = useState(false)
+    const [isDrawioReady, setIsDrawioReady] = useState(false)
    const [closeProtection, setCloseProtection] = useState(false)

    const chatPanelRef = useRef<ImperativePanelHandle>(null)
@@ -104,12 +105,18 @@ export default function Home() {
        setIsLoaded(true)
    }, [pathname, router])

+    const handleDrawioLoad = useCallback(() => {
+        setIsDrawioReady(true)
+        onDrawioLoad()
+    }, [onDrawioLoad])
+
    const handleDarkModeChange = async () => {
        await saveDiagramToStorage()
        const newValue = !darkMode
        setDarkMode(newValue)
        localStorage.setItem("next-ai-draw-io-dark-mode", String(newValue))
        document.documentElement.classList.toggle("dark", newValue)
+        setIsDrawioReady(false)
        resetDrawioReady()
    }

@@ -118,6 +125,7 @@ export default function Home() {
        const newUi = drawioUi === "min" ? "sketch" : "min"
        localStorage.setItem("drawio-theme", newUi)
        setDrawioUi(newUi)
+        setIsDrawioReady(false)
        resetDrawioReady()
    }

@@ -131,6 +139,7 @@ export default function Home() {
                newIsMobile !== isMobileRef.current
            ) {
                saveDiagramToStorage().catch(() => {})
+                setIsDrawioReady(false)
                resetDrawioReady()
            }
            isMobileRef.current = newIsMobile
@@ -206,28 +215,35 @@ export default function Home() {
                            mouseOverDrawioRef.current = false
                        }}
                    >
-                        <div className="h-full rounded-xl overflow-hidden shadow-soft-lg border border-border/30">
-                            {isLoaded ? (
-                                <DrawIoEmbed
-                                    key={`${drawioUi}-${darkMode}-${currentLang}`}
-                                    ref={drawioRef}
-                                    onExport={handleDiagramExport}
-                                    onLoad={onDrawioLoad}
-                                    onSave={handleDrawioSave}
-                                    baseUrl={drawioBaseUrl}
-                                    urlParameters={{
-                                        ui: drawioUi,
-                                        spin: true,
-                                        libraries: false,
-                                        saveAndExit: false,
-                                        noExitBtn: true,
-                                        dark: darkMode,
-                                        lang: currentLang,
-                                    }}
-                                />
-                            ) : (
-                                <div className="h-full w-full flex items-center justify-center bg-background">
-                                    <div className="animate-spin h-8 w-8 border-4 border-primary border-t-transparent rounded-full" />
+                        <div className="h-full rounded-xl overflow-hidden shadow-soft-lg border border-border/30 relative">
+                            {isLoaded && (
+                                <div
+                                    className={`h-full w-full ${isDrawioReady ? "" : "invisible absolute inset-0"}`}
+                                >
+                                    <DrawIoEmbed
+                                        key={`${drawioUi}-${darkMode}-${currentLang}`}
+                                        ref={drawioRef}
+                                        onExport={handleDiagramExport}
+                                        onLoad={handleDrawioLoad}
+                                        onSave={handleDrawioSave}
+                                        baseUrl={drawioBaseUrl}
+                                        urlParameters={{
+                                            ui: drawioUi,
+                                            spin: false,
+                                            libraries: false,
+                                            saveAndExit: false,
+                                            noExitBtn: true,
+                                            dark: darkMode,
+                                            lang: currentLang,
+                                        }}
+                                    />
+                                </div>
+                            )}
+                            {(!isLoaded || !isDrawioReady) && (
+                                <div className="h-full w-full bg-background flex items-center justify-center">
+                                    <span className="text-muted-foreground">
+                                        Draw.io panel is loading...
+                                    </span>
                                </div>
                            )}
                        </div>
--- a/components/chat-message-display.tsx
+++ b/components/chat-message-display.tsx
@@ -193,6 +193,7 @@ interface ChatMessageDisplayProps {
    onRegenerate?: (messageIndex: number) => void
    onEditMessage?: (messageIndex: number, newText: string) => void
    status?: "streaming" | "submitted" | "idle" | "error" | "ready"
+    isRestored?: boolean
 }

 export function ChatMessageDisplay({
@@ -205,6 +206,7 @@ export function ChatMessageDisplay({
    onRegenerate,
    onEditMessage,
    status = "idle",
+    isRestored = false,
 }: ChatMessageDisplayProps) {
    const dict = useDictionary()
    const { chartXML, loadDiagram: onDisplayChart } = useDiagram()
@@ -250,6 +252,15 @@ export function ChatMessageDisplay({
    const [expandedPdfSections, setExpandedPdfSections] = useState<
        Record<string, boolean>
    >({})
+    // Track message IDs that were restored from localStorage (skip animation for these)
+    const restoredMessageIdsRef = useRef<Set<string> | null>(null)
+
+    // Capture restored message IDs once when isRestored becomes true
+    useEffect(() => {
+        if (isRestored && restoredMessageIdsRef.current === null) {
+            restoredMessageIdsRef.current = new Set(messages.map((m) => m.id))
+        }
+    }, [isRestored, messages])

    const setCopyState = (
        messageId: string,
@@ -669,7 +680,8 @@ export function ChatMessageDisplay({
    const renderToolPart = (part: ToolPartLike) => {
        const callId = part.toolCallId
        const { state, input, output } = part
-        const isExpanded = expandedTools[callId] ?? true
+        // Default to collapsed if tool is complete, expanded if still streaming
+        const isExpanded = expandedTools[callId] ?? state !== "output-available"
        const toolName = part.type?.replace("tool-", "")
        const isCopied = copiedToolCallId === callId

@@ -859,9 +871,9 @@ export function ChatMessageDisplay({

    return (
        <ScrollArea className="h-full w-full scrollbar-thin">
-            {messages.length === 0 ? (
+            {messages.length === 0 && isRestored ? (
                <ExamplePanel setInput={setInput} setFiles={setFiles} />
-            ) : (
+            ) : messages.length === 0 ? null : (
                <div className="py-4 px-4 space-y-4">
                    {messages.map((message, messageIndex) => {
                        const userMessageText =
@@ -881,13 +893,23 @@ export function ChatMessageDisplay({
                                    .slice(messageIndex + 1)
                                    .every((m) => m.role !== "user"))
                        const isEditing = editingMessageId === message.id
+                        // Skip animation for restored messages
+                        // If isRestored but ref not set yet, we're in first render after restoration - treat all as restored
+                        const isRestoredMessage =
+                            isRestored &&
+                            (restoredMessageIdsRef.current === null ||
+                                restoredMessageIdsRef.current.has(message.id))
                        return (
                            <div
                                key={message.id}
-                                className={`flex w-full ${message.role === "user" ? "justify-end" : "justify-start"} animate-message-in`}
-                                style={{
-                                    animationDelay: `${messageIndex * 50}ms`,
-                                }}
+                                className={`flex w-full ${message.role === "user" ? "justify-end" : "justify-start"} ${isRestoredMessage ? "" : "animate-message-in"}`}
+                                style={
+                                    isRestoredMessage
+                                        ? undefined
+                                        : {
+                                              animationDelay: `${messageIndex * 50}ms`,
+                                          }
+                                }
                            >
                                {message.role === "user" &&
                                    userMessageText &&
@@ -984,6 +1006,9 @@ export function ChatMessageDisplay({
                                                            isStreaming={
                                                                isStreamingReasoning
                                                            }
+                                                            defaultOpen={
+                                                                !isRestoredMessage
+                                                            }
                                                        >
                                                            <ReasoningTrigger />
                                                            <ReasoningContent>
--- a/components/chat-panel.tsx
+++ b/components/chat-panel.tsx
@@ -201,6 +201,7 @@ export default function ChatPanel({

    // Flag to track if we've restored from localStorage
    const hasRestoredRef = useRef(false)
+    const [isRestored, setIsRestored] = useState(false)

    // Ref to track latest chartXML for use in callbacks (avoids stale closure)
    const chartXMLRef = useRef(chartXML)
@@ -457,6 +458,8 @@ export default function ChatPanel({
            localStorage.removeItem(STORAGE_MESSAGES_KEY)
            localStorage.removeItem(STORAGE_XML_SNAPSHOTS_KEY)
            toast.error(dict.errors.sessionCorrupted)
+        } finally {
+            setIsRestored(true)
        }
    }, [setMessages])

@@ -1006,6 +1009,7 @@ export default function ChatPanel({
                    onRegenerate={handleRegenerate}
                    status={status}
                    onEditMessage={handleEditMessage}
+                    isRestored={isRestored}
                />
            </main>

--- a/packages/mcp-server/README.md
+++ b/packages/mcp-server/README.md
@@ -90,7 +90,7 @@ Use the standard MCP configuration with:
 - **Natural Language**: Describe diagrams in plain text - flowcharts, architecture diagrams, etc.
 - **Edit Support**: Modify existing diagrams with natural language instructions
 - **Export**: Save diagrams as `.drawio` files
- **Self-contained**: Embedded server, works offline (except draw.io UI which loads from embed.diagrams.net)
+- **Self-contained**: Embedded server, works offline (except draw.io UI which loads from `embed.diagrams.net` by default, configurable via `DRAWIO_BASE_URL`)

 ## Available Tools

@@ -130,6 +130,33 @@ Use the standard MCP configuration with:
 | Variable | Default | Description |
 |----------|---------|-------------|
 | `PORT` | `6002` | Port for the embedded HTTP server |
+| `DRAWIO_BASE_URL` | `https://embed.diagrams.net` | Base URL for the draw.io embed. Set this to use a self-hosted draw.io instance for private deployments. |
+
+### Private Deployment (Self-hosted draw.io)
+
+For security-sensitive environments that require private deployment of draw.io:
+
+```json
+{
+  "mcpServers": {
+    "drawio": {
+      "command": "npx",
+      "args": ["@next-ai-drawio/mcp-server@latest"],
+      "env": { 
+        "DRAWIO_BASE_URL": "https://drawio.your-company.com"
+      }
+    }
+  }
+}
+```
+
+You can deploy your own draw.io instance using the official Docker image:
+
+```bash
+docker run -d -p 8080:8080 jgraph/drawio
+```
+
+Then set `DRAWIO_BASE_URL=http://localhost:8080` (or your server's URL).

 ## Troubleshooting

--- a/packages/mcp-server/src/http-server.ts
+++ b/packages/mcp-server/src/http-server.ts
@@ -13,6 +13,28 @@ import {
 } from "./history.js"
 import { log } from "./logger.js"

+// Configurable draw.io embed URL for private deployments
+const DRAWIO_BASE_URL =
+    process.env.DRAWIO_BASE_URL || "https://embed.diagrams.net"
+
+// Extract origin (scheme + host + port) from URL for postMessage security check
+function getOrigin(url: string): string {
+    try {
+        const parsed = new URL(url)
+        return `${parsed.protocol}//${parsed.host}`
+    } catch {
+        return url // Fallback if parsing fails
+    }
+}
+
+const DRAWIO_ORIGIN = getOrigin(DRAWIO_BASE_URL)
+
+// Normalize URL for iframe src - ensure no double slashes
+function normalizeUrl(url: string): string {
+    // Remove trailing slash to avoid double slashes
+    return url.replace(/\/$/, "")
+}
+
 interface SessionState {
    xml: string
    version: number
@@ -403,7 +425,7 @@ function getHtmlPage(sessionId: string): string {
            </div>
            <div id="status" class="status disconnected">Connecting...</div>
        </div>
-        <iframe id="drawio" src="https://embed.diagrams.net/?embed=1&proto=json&spin=1&libraries=1"></iframe>
+        <iframe id="drawio" src="${normalizeUrl(DRAWIO_BASE_URL)}/?embed=1&proto=json&spin=1&libraries=1"></iframe>
    </div>
    <button id="history-btn" title="History" ${sessionId ? "" : "disabled"}>
        <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
@@ -433,7 +455,7 @@ function getHtmlPage(sessionId: string): string {
        let pendingAiSvg = false;

        window.addEventListener('message', (e) => {
-            if (e.origin !== 'https://embed.diagrams.net') return;
+            if (e.origin !== '${DRAWIO_ORIGIN}') return;
            try {
                const msg = JSON.parse(e.data);
                if (msg.event === 'init') {