fix(练习): 修复知识领域显示和输入焦点问题

- 隐藏未答对的知识领域名称，只在答对后显示
- 增加底部输入区域透明度（80% -> 60%）
- 修复切换格子后输入框未自动聚焦的问题
- 优化连续输入处理，支持多字符自动分配到后续输入框

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>

src/components/practice/InputArea.tsx

@@ -41,13 +41,27 @@ export function InputArea({
     if (inputLocked) return
 
     const newInput = [...userInput]
-    // 只取第一个字符
-    newInput[index] = value.slice(0, 1)
-    onInputChange(newInput)
 
-    // 自动跳转到下一个输入框
-    if (value && index < userInput.length - 1) {
-      inputRefs.current[index + 1]?.focus()
+    // 处理多字符输入（连续输入或粘贴）
+    if (value.length > 1) {
+      const chars = value.split('')
+      for (let i = 0; i < chars.length && index + i < userInput.length; i++) {
+        newInput[index + i] = chars[i]
+      }
+      onInputChange(newInput)
+
+      // 聚焦到最后填充的位置的下一个
+      const nextIndex = Math.min(index + chars.length, userInput.length - 1)
+      inputRefs.current[nextIndex]?.focus()
+    } else {
+      // 单字符输入
+      newInput[index] = value
+      onInputChange(newInput)
+
+      // 自动跳转到下一个输入框
+      if (value && index < userInput.length - 1) {
+        inputRefs.current[index + 1]?.focus()
+      }
     }
   }
 
@@ -80,7 +94,7 @@ export function InputArea({
   }
 
   return (
-    <div className="flex flex-col items-center gap-4">
+    <div className="flex flex-col items-center gap-4 practice-input-area">
       <div className="flex gap-3">
         {userInput.map((char, index) => {
           const status = charStatuses[index] || 'pending'

src/components/practice/PracticeMatrix.tsx

@@ -1,6 +1,8 @@
 import { knowledgeAreas, processGroups } from '@/data'
 import { getProcessesByKaAndPg } from '@/utils/practice'
 import { ProcessCell } from './ProcessCell'
+import { useLongPress } from '@/hooks/useLongPress'
+import clsx from 'clsx'
 
 interface PracticeMatrixProps {
   answeredCells: Map<string, boolean>
@@ -12,6 +14,77 @@ interface PracticeMatrixProps {
   getCellTabIndex: (cellId: string) => number
 }
 
+interface KnowledgeAreaCellProps {
+  ka: any
+  isAnswered: boolean
+  isFocused: boolean
+  showAnswer?: string | null
+  onLongPress: (cellId: string) => void
+  onLongPressEnd: () => void
+  onClick: (cellId: string) => void
+  tabIndex: number
+}
+
+function KnowledgeAreaCell({
+  ka,
+  isAnswered,
+  isFocused,
+  showAnswer,
+  onLongPress,
+  onLongPressEnd,
+  onClick,
+  tabIndex,
+}: KnowledgeAreaCellProps) {
+  const cellId = `ka-${ka.id}`
+  const longPressHandlers = useLongPress(cellId, {
+    onLongPress,
+    onLongPressEnd,
+  })
+
+  return (
+    <td
+      data-cell-id={cellId}
+      className={clsx(
+        'sticky left-0 z-10 p-2 border border-gray-200 dark:border-gray-700 font-medium cursor-pointer transition-all duration-200',
+        isFocused && 'ring-2 ring-blue-500 ring-inset',
+        !isAnswered && 'border-dashed'
+      )}
+      style={{
+        backgroundColor: isAnswered ? `${ka.color}15` : 'transparent',
+        borderLeftWidth: 4,
+        borderLeftColor: isFocused ? '#3b82f6' : ka.color,
+      }}
+      onClick={() => onClick(cellId)}
+      tabIndex={tabIndex}
+      role="button"
+      aria-label={`知识领域：${ka.name}`}
+      {...longPressHandlers}
+    >
+      {isAnswered ? (
+        <div className="flex items-center gap-2">
+          <span className="font-bold text-xs" style={{ color: ka.color }}>
+            {ka.order}
+          </span>
+          <span className="text-xs text-gray-900 dark:text-white">
+            {ka.name}
+          </span>
+        </div>
+      ) : (
+        <div className="min-h-[24px]" />
+      )}
+
+      {/* 长按显示答案 */}
+      {showAnswer && (
+        <div className="absolute inset-0 flex items-center justify-center bg-black/80 rounded z-20">
+          <span className="text-white text-sm font-medium px-2 text-center">
+            {showAnswer}
+          </span>
+        </div>
+      )}
+    </td>
+  )
+}
+
 export function PracticeMatrix({
   answeredCells,
   currentCellId,
@@ -48,26 +121,24 @@ export function PracticeMatrix({
         {/* 表体：知识领域 × 过程 */}
         <tbody>
           {sortedKAs.map((ka) => {
+            const kaCellId = `ka-${ka.id}`
             return (
               <tr key={ka.id}>
                 {/* 知识领域名称 */}
-                <td
-                  className="sticky left-0 z-10 p-2 border border-gray-200 dark:border-gray-700 font-medium"
-                  style={{
-                    backgroundColor: `${ka.color}15`,
-                    borderLeftWidth: 4,
-                    borderLeftColor: ka.color,
-                  }}
-                >
-                  <div className="flex items-center gap-2">
-                    <span className="font-bold text-xs" style={{ color: ka.color }}>
-                      {ka.order}
-                    </span>
-                    <span className="text-xs text-gray-900 dark:text-white">
-                      {ka.name}
-                    </span>
-                  </div>
-                </td>
+                <KnowledgeAreaCell
+                  ka={ka}
+                  isAnswered={answeredCells.get(kaCellId) || false}
+                  isFocused={currentCellId === kaCellId}
+                  showAnswer={
+                    showAnswerForCell?.cellId === kaCellId
+                      ? showAnswerForCell.answer
+                      : null
+                  }
+                  onLongPress={onLongPress}
+                  onLongPressEnd={onLongPressEnd}
+                  onClick={onCellClick}
+                  tabIndex={getCellTabIndex(kaCellId)}
+                />
 
                 {/* 每个过程组的单元格 */}
                 {sortedPGs.map((pg) => {

src/pages/ProcessPracticePage.tsx

@@ -57,17 +57,21 @@ export default function ProcessPracticePage() {
       setCharStatuses(new Array(cell.answer.length).fill('pending'))
       setLastErrorTimestamp(null)
 
-      // 滚动到可见区域并聚焦
+      // 滚动到可见区域
       requestAnimationFrame(() => {
         const element = document.querySelector(
           `[data-cell-id="${cell.id}"]`
         ) as HTMLElement
         element?.scrollIntoView({ behavior: 'smooth', block: 'center' })
-        // 聚焦格子，使键盘长按生效
-        setTimeout(() => {
-          element?.focus()
-        }, 100)
       })
+
+      // 延迟聚焦到第一个输入框，确保 DOM 已更新
+      setTimeout(() => {
+        const firstInput = document.querySelector(
+          '.practice-input-area input'
+        ) as HTMLInputElement
+        firstInput?.focus()
+      }, 150)
     },
     []
   )
@@ -314,7 +318,7 @@ export default function ProcessPracticePage() {
       </div>
 
       {/* 底部固定区域 */}
-      <div className="fixed bottom-0 left-0 right-0 bg-white/80 dark:bg-gray-800/80 backdrop-blur-md border-t border-gray-200 dark:border-gray-700 z-10">
+      <div className="fixed bottom-0 left-0 right-0 bg-white/60 dark:bg-gray-800/60 backdrop-blur-md border-t border-gray-200 dark:border-gray-700 z-10">
         <div className="max-w-7xl mx-auto">
           {/* 输入区域 */}
           <div className="py-4 border-b border-gray-200/50 dark:border-gray-700/50">