refactor: useLayoutEffect for no-flash position init, clean localStorage save, hide toolbar until ready

src/app/client/client-view.tsx

@@ -7,6 +7,7 @@ import {
 	type ReactNode,
 	useCallback,
 	useEffect,
+	useLayoutEffect,
 	useRef,
 	useState,
 } from "react";
@@ -99,10 +100,11 @@ export function ClientView({
 
 	const toolbarRef = useRef<HTMLDivElement>(null);
 	const dragRef = useRef({ startX: 0, startY: 0, startTop: 0, startLeft: 0 });
-	const [pos, setPos] = useState({ top: 8, left: -1 });
+	const posRef = useRef({ top: 8, left: 8 });
+	const [pos, setPos] = useState<{ top: number; left: number } | null>(null);
 	const [dragging, setDragging] = useState(false);
 
-	useEffect(() => {
+	useLayoutEffect(() => {
 		const params = new URLSearchParams(window.location.search);
 		const ux = params.get("toolbarX"), uy = params.get("toolbarY");
 		if (ux && uy) { setPos({ top: Number(uy), left: Number(ux) }); return; }
@@ -117,9 +119,10 @@ export function ClientView({
 		setPos({ top: 8, left: window.innerWidth - w - 8 });
 	}, []);
 
+	useEffect(() => { if (pos) posRef.current = pos; }, [pos]);
+
 	const startDrag = useCallback((clientX: number, clientY: number) => {
-		const el = toolbarRef.current;
-		if (!el) return;
+		if (!pos) return;
 		dragRef.current = {
 			startX: clientX,
 			startY: clientY,
@@ -127,7 +130,7 @@ export function ClientView({
 			startLeft: pos.left,
 		};
 		setDragging(true);
-	}, [pos.top, pos.left]);
+	}, [pos]);
 
 	const handleMouseDown = useCallback((e: React.MouseEvent) => {
 		if ((e.target as HTMLElement).closest("button, a")) return;
@@ -162,13 +165,11 @@ export function ClientView({
 		}
 		function onEnd() {
 			setDragging(false);
-			setPos(p => {
-				try {
-					localStorage.setItem("client_toolbar_x", String(p.left));
-					localStorage.setItem("client_toolbar_y", String(p.top));
-				} catch {}
-				return p;
-			});
+			setPos(p => p);
+			try {
+				localStorage.setItem("client_toolbar_x", String(posRef.current.left));
+				localStorage.setItem("client_toolbar_y", String(posRef.current.top));
+			} catch {}
 		}
 		window.addEventListener("mousemove", onMove);
 		window.addEventListener("mouseup", onEnd);
@@ -184,13 +185,14 @@ export function ClientView({
 
 	return (
 		<>
-			<div
-				ref={toolbarRef}
-				className={`fixed z-[9999] flex items-center gap-1 sm:gap-2 select-none ${dragging ? "cursor-grabbing" : "cursor-grab"}`}
-				style={{ top: pos.top, left: pos.left >= 0 ? pos.left : undefined, right: pos.left < 0 ? 8 : undefined }}
-				onMouseDown={handleMouseDown}
-				onTouchStart={handleTouchStart}
-			>
+			{pos ? (
+				<div
+					ref={toolbarRef}
+					className={`fixed z-[9999] flex items-center gap-1 sm:gap-2 select-none ${dragging ? "cursor-grabbing" : "cursor-grab"}`}
+					style={{ top: pos.top, left: pos.left }}
+					onMouseDown={handleMouseDown}
+					onTouchStart={handleTouchStart}
+				>
 				<ToolbarBtn href="/" title="Home">
 					<svg
 						width="14"
@@ -312,6 +314,7 @@ export function ClientView({
 					<LogOut size={14} />
 				</ToolbarBtn>
 			</div>
+			) : null}
 
 			<div
 				className="relative w-screen h-screen overflow-hidden"