skeleton loading

frontend/src/components/tools/ToolPanel.tsx

@@ -109,10 +109,12 @@ export default function ToolPanel() {
           <div className="flex-1 flex flex-col">
             {/* Tool content */}
             <div className="flex-1 min-h-0">
+              {selectedToolKey && (
                 <ToolRenderer
                   selectedToolKey={selectedToolKey}
                   onPreviewFile={setPreviewFile}
                 />
+              )}
             </div>
           </div>
         )}

frontend/src/components/tools/shared/ToolStep.tsx

@@ -1,4 +1,4 @@
-import React, { createContext, useContext, useMemo, useRef } from 'react';
+import React, { createContext, useContext, useMemo, useRef, useEffect, useState } from 'react';
 import { Paper, Text, Stack, Box, Flex } from '@mantine/core';
 import ExpandMoreIcon from '@mui/icons-material/ExpandMore';
 import ChevronRightIcon from '@mui/icons-material/ChevronRight';
@@ -22,6 +22,10 @@ export interface ToolStepProps {
   completedMessage?: string;
   helpText?: string;
   showNumber?: boolean;
+  /** Show a brief skeleton for smoother tool transitions */
+  enableInitialSkeleton?: boolean;
+  /** Duration for the initial skeleton in milliseconds */
+  initialSkeletonMs?: number;
   tooltip?: {
     content?: React.ReactNode;
     tips?: TooltipTip[];
@@ -74,6 +78,8 @@ const ToolStep = ({
   completedMessage,
   helpText,
   showNumber,
+  enableInitialSkeleton = true,
+  initialSkeletonMs = 800,
   tooltip
 }: ToolStepProps) => {
   if (!isVisible) return null;
@@ -88,6 +94,16 @@ const ToolStep = ({
 
   const stepNumber = parent?.getStepNumber?.() || 1;
 
+   // Show a step-sized skeleton immediately after mount to indicate tool switch
+  const [showInitialSkeleton, setShowInitialSkeleton] = useState(enableInitialSkeleton);
+  useEffect(() => {
+    if (!enableInitialSkeleton) return;
+    setShowInitialSkeleton(true);
+    const id = setTimeout(() => setShowInitialSkeleton(false), initialSkeletonMs);
+    return () => clearTimeout(id);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
   return (
     <Paper
       p="md"
@@ -109,11 +125,19 @@ const ToolStep = ({
       >
         <Flex align="center" gap="sm">
           {shouldShowNumber && (
+            showInitialSkeleton ? (
+              <Box w={18} h={18} bg="gray.1" style={{ borderRadius: 4 }} />
+            ) : (
               <Text fw={500} size="lg" c="dimmed">
                 {stepNumber}
               </Text>
+            )
+          )}
+          {showInitialSkeleton ? (
+            <Box w={80} h={20} bg="gray.1" style={{ borderRadius: 4 }} />
+          ) : (
+            renderTooltipTitle(title, tooltip, isCollapsed)
           )}
-          {renderTooltipTitle(title, tooltip, isCollapsed)}
         </Flex>
         
         {isCollapsed ? (
@@ -133,7 +157,10 @@ const ToolStep = ({
 
       {isCollapsed ? (
         <Box>
-          {isCompleted && completedMessage && (
+          {showInitialSkeleton ? (
+            <Box w="40%" h={14} bg="gray.1" style={{ borderRadius: 4 }} />
+          ) : (
+            isCompleted && completedMessage && (
               <Text size="sm" c="green">
                 ✓ {completedMessage}
                 {onCollapsedClick && (
@@ -142,6 +169,7 @@ const ToolStep = ({
                   </Text>
                 )}
               </Text>
+            )
           )}
         </Box>
       ) : (
@@ -151,7 +179,16 @@ const ToolStep = ({
               {helpText}
             </Text>
           )}
-          {children}
+          {showInitialSkeleton ? (
+            <>
+              <Box w="80%" h={16} bg="gray.1" style={{ borderRadius: 4 }} />
+              <Box w="60%" h={16} bg="gray.1" style={{ borderRadius: 4 }} />
+              <Box w="100%" h={44} bg="gray.1" style={{ borderRadius: 8 }} />
+              <Box w="100%" h={44} bg="gray.1" style={{ borderRadius: 8 }} />
+            </>
+          ) : (
+            children
+          )}
         </Stack>
       )}
     </Paper>

frontend/src/data/toolRegistry.tsx

@@ -514,33 +514,6 @@ export const flatToolRegistryMap: ToolRegistry = {
         category: "Standard Tools",
         subcategory: "Page Formatting"
     },
-    "split": {
-        icon: <span className="material-symbols-rounded">content_cut</span>,
-        name: "home.split.title",
-        component: null,
-        view: "format",
-        description: "home.split.desc",
-        category: "Standard Tools",
-        subcategory: "Page Formatting"
-    },
-    "split-by-chapters": {
-        icon: <span className="material-symbols-rounded">collections_bookmark</span>,
-        name: "home.splitPdfByChapters.title",
-        component: null,
-        view: "format",
-        description: "home.splitPdfByChapters.desc",
-        category: "Advanced Tools",
-        subcategory: "Advanced Formatting"
-    },
-    "split-by-sections": {
-        icon: <span className="material-symbols-rounded">grid_on</span>,
-        name: "home.split-by-sections.title",
-        component: null,
-        view: "format",
-        description: "home.split-by-sections.desc",
-        category: "Advanced Tools",
-        subcategory: "Advanced Formatting"
-    },
     "splitPdf": {
         icon: <span className="material-symbols-rounded">content_cut</span>,
         name: "home.split.title",
@@ -594,7 +567,7 @@ function buildStructuredRegistry(): ToolRegistryStructured {
     for (const [id, tool] of entries) {
         const sub = tool.subcategory ?? 'General';
         const cat = tool.category ?? 'OTHER';
-        // Quick access: use the existing "Recommended Tools" category
+        // Quick access: use the existing "Recommended Tools" category, this will change in future
         if (tool.category === 'Recommended Tools') {
             quick.push({ id, ...tool });
         }

frontend/src/tools/Compress.tsx

@@ -102,6 +102,7 @@ const Compress = ({ onPreviewFile, onComplete, onError }: BaseToolProps) => {
         <ToolStep
           title="Settings"
           isVisible={hasFiles}
+          enableInitialSkeleton={false}
           isCollapsed={settingsCollapsed}
           isCompleted={settingsCollapsed}
           onCollapsedClick={settingsCollapsed ? handleSettingsReset : undefined}
@@ -129,6 +130,7 @@ const Compress = ({ onPreviewFile, onComplete, onError }: BaseToolProps) => {
         <ToolStep
           title="Results"
           isVisible={hasResults}
+          enableInitialSkeleton={false}
         >
           <Stack gap="sm">
             {compressOperation.status && (

frontend/src/tools/Convert.tsx

@@ -163,6 +163,7 @@ const Convert = ({ onPreviewFile, onComplete, onError }: BaseToolProps) => {
         <ToolStep
           title={t("convert.results", "Results")}
           isVisible={hasResults}
+          enableInitialSkeleton={false}
           data-testid="conversion-results"
         >
           <Stack gap="sm">

frontend/src/tools/Split.tsx

@@ -96,7 +96,8 @@ const Split = ({ onPreviewFile, onComplete, onError }: BaseToolProps) => {
         {/* Settings Step */}
         <ToolStep
           title="Settings"
-          isVisible={hasFiles}
+          isVisible={true}
+          enableInitialSkeleton={true}
           isCollapsed={settingsCollapsed}
           isCompleted={settingsCollapsed}
           onCollapsedClick={settingsCollapsed ? handleSettingsReset : undefined}
@@ -125,6 +126,7 @@ const Split = ({ onPreviewFile, onComplete, onError }: BaseToolProps) => {
         <ToolStep
           title="Results"
           isVisible={hasResults}
+          enableInitialSkeleton={false}
         >
           <Stack gap="sm">
             {splitOperation.status && (