preload flutter

apps/web/src/components/flutter-view.tsx

@@ -28,60 +28,52 @@ declare global {
   }
 }
 
-type FlutterViewProps = {
-  state: FlutterTimelineState;
-  onEvent: (event: FlutterEvent) => void;
-  className?: string;
-  height?: number;
-};
+// ---------------------------------------------------------------------------
+// Module-level singleton state
+// ---------------------------------------------------------------------------
 
-export function FlutterView({
-  state,
-  onEvent,
-  className,
-  height,
-}: FlutterViewProps) {
-  const containerRef = useRef<HTMLDivElement>(null);
-  const [status, setStatus] = useState<"loading" | "ready" | "error">(
-    "loading"
-  );
-  const stateRef = useRef(state);
-  stateRef.current = state;
+let flutterContainer: HTMLDivElement | null = null;
+let engineReady = false;
+let initPromise: Promise<void> | null = null;
 
-  const onEventRef = useRef(onEvent);
-  onEventRef.current = onEvent;
-
-  useEffect(() => {
-    const container = containerRef.current;
-    if (!container) return;
-
-    let pollingInterval: ReturnType<typeof setInterval> | undefined;
-    let pollingTimeout: ReturnType<typeof setTimeout> | undefined;
+// Module-level refs so bridge closures always read latest values
+let currentStateRef: FlutterTimelineState | null = null;
+let currentOnEventRef: ((event: FlutterEvent) => void) | null = null;
 
+function ensureBridge() {
+  if (window.__zendegi__) return;
   window.__zendegi__ = {
-      getState: () => JSON.stringify(stateRef.current),
+    getState: () => JSON.stringify(currentStateRef),
     onEvent: (json: string) => {
       const event = JSON.parse(json) as FlutterEvent;
-        onEventRef.current(event);
+      currentOnEventRef?.(event);
     },
   };
+}
 
-    const init = async () => {
+export function preloadFlutter() {
+  initFlutter();
+}
+
+function initFlutter(): Promise<void> {
+  if (initPromise) return initPromise;
+
+  initPromise = (async () => {
+    ensureBridge();
     // Load flutter.js if not already loaded
     if (!window._flutter) {
       await new Promise<void>((resolve, reject) => {
         if (document.querySelector('script[src="/flutter/flutter.js"]')) {
-            // Script tag exists but hasn't finished — wait for _flutter to appear
-            pollingTimeout = setTimeout(() => {
-              clearInterval(pollingInterval);
+          const timeout = setTimeout(() => {
+            clearInterval(interval);
             reject(
-                new Error("Timed out waiting for flutter.js to initialize")
+              new Error("Timed out waiting for flutter.js to initialize"),
             );
           }, 10_000);
-            pollingInterval = setInterval(() => {
+          const interval = setInterval(() => {
             if (window._flutter) {
-                clearInterval(pollingInterval);
-                clearTimeout(pollingTimeout);
+              clearInterval(interval);
+              clearTimeout(timeout);
               resolve();
             }
           }, 50);
@@ -105,7 +97,13 @@ export function FlutterView({
       window._flutter!.buildConfig = await res.json();
     }
 
-      try {
+    // Create the persistent container once
+    if (!flutterContainer) {
+      flutterContainer = document.createElement("div");
+      flutterContainer.style.width = "100%";
+      flutterContainer.style.height = "100%";
+    }
+
     await window._flutter!.loader.load({
       config: {
         entrypointBaseUrl: "/flutter/",
@@ -113,27 +111,81 @@ export function FlutterView({
       },
       onEntrypointLoaded: async (engineInitializer) => {
         const appRunner = await engineInitializer.initializeEngine({
-              hostElement: container,
+          hostElement: flutterContainer!,
           assetBase: "/flutter/",
         });
         appRunner.runApp();
-            setStatus("ready");
       },
     });
-      } catch (error) {
-        throw new Error(
-          `Flutter engine initialization failed: ${error instanceof Error ? error.message : error}`
-        );
+
+    engineReady = true;
+  })().catch((error) => {
+    // Reset all module state so next mount retries
+    flutterContainer = null;
+    engineReady = false;
+    initPromise = null;
+    throw error;
+  });
+
+  return initPromise;
 }
+
+// ---------------------------------------------------------------------------
+// Component
+// ---------------------------------------------------------------------------
+
+type FlutterViewProps = {
+  state: FlutterTimelineState;
+  onEvent: (event: FlutterEvent) => void;
+  className?: string;
+  height?: number;
 };
 
-    init().catch(() => setStatus("error"));
+export function FlutterView({
+  state,
+  onEvent,
+  className,
+  height,
+}: FlutterViewProps) {
+  const containerRef = useRef<HTMLDivElement>(null);
+  const [status, setStatus] = useState<"loading" | "ready" | "error">(
+    engineReady ? "ready" : "loading",
+  );
+
+  // Keep module-level refs in sync
+  currentStateRef = state;
+  currentOnEventRef = onEvent;
+
+  useEffect(() => {
+    const wrapper = containerRef.current;
+    if (!wrapper) return;
+
+    if (engineReady && flutterContainer) {
+      // Engine already running — reparent immediately, no loading flash
+      wrapper.appendChild(flutterContainer);
+      setStatus("ready");
+      // Push latest state so Flutter renders the correct timeline
+      window.__zendegi__?.updateState?.(JSON.stringify(currentStateRef));
+    } else {
+      // First mount — initialize engine
+      setStatus("loading");
+      initFlutter()
+        .then(() => {
+          // Guard: component may have unmounted while awaiting
+          if (!containerRef.current || !flutterContainer) return;
+          wrapper.appendChild(flutterContainer);
+          setStatus("ready");
+          // Push current state after engine is ready
+          window.__zendegi__?.updateState?.(JSON.stringify(currentStateRef));
+        })
+        .catch(() => setStatus("error"));
+    }
 
     return () => {
-      clearInterval(pollingInterval);
-      clearTimeout(pollingTimeout);
-      container.replaceChildren();
-      delete (window as Partial<Window>).__zendegi__;
+      // Detach but don't destroy the Flutter container
+      if (flutterContainer?.parentElement === wrapper) {
+        wrapper.removeChild(flutterContainer);
+      }
     };
   }, []);
 

apps/web/src/routes/_default.timelines.tsx

@@ -1,6 +1,8 @@
+import { useEffect } from "react";
 import { createFileRoute, Link } from "@tanstack/react-router";
 import { useSuspenseQuery } from "@tanstack/react-query";
 import { timelinesQueryOptions } from "@/functions/get-timelines";
+import { preloadFlutter } from "@/components/flutter-view";
 
 export const Route = createFileRoute("/_default/timelines")({
   loader: async ({ context }) => {
@@ -11,6 +13,10 @@ export const Route = createFileRoute("/_default/timelines")({
 
 function RouteComponent() {
   const timelinesQuery = useSuspenseQuery(timelinesQueryOptions());
+
+  useEffect(() => {
+    preloadFlutter();
+  }, []);
   return (
     <section className="container mx-auto max-w-3xl px-4 py-2">
       <h1 className="text-4xl font-serif font-bold mb-6">Timelines</h1>