feat: 完善听力口语辅助状态记录、练习分块与复习抽查间隔机制

kouyu_english/lib/features/lesson/steps/speaking_step.dart

@@ -6,15 +6,23 @@ class _SpeakingStep extends StatefulWidget {
     required this.segmentId,
     required this.text,
     this.tip = '',
+    this.chunks = const [],
+    this.examples = const [],
+    required this.buildIndex,
+    required this.onBuildProgress,
     required this.keepRecording,
     required this.onContinue,
   });
   final String segmentId;
   final String text;
   final String tip;
+  final List<String> chunks;
+  final List<String> examples;
+  final int buildIndex;
+  final ValueChanged<int> onBuildProgress;
   final AppState state;
   final bool keepRecording;
-  final VoidCallback onContinue;
+  final ValueChanged<bool> onContinue;
 
   @override
   State<_SpeakingStep> createState() => _SpeakingStepState();
@@ -89,12 +97,57 @@ class _SpeakingStepState extends State<_SpeakingStep>
         if (widget.tip.isNotEmpty)
           SectionCard(
             tint: AppColors.warm,
-            child: Text(
-              widget.tip,
-              style: TextStyle(color: AppColors.warmInk),
-            ),
+            child: Text(widget.tip, style: TextStyle(color: AppColors.warmInk)),
           ),
         SegmentUsage(segmentId: widget.segmentId, state: widget.state),
+        if (widget.chunks.length >= 2)
+          SectionCard(
+            tint: AppColors.surfaceMuted,
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                const Text('拆开练（可选）'),
+                const SizedBox(height: 8),
+                Text(
+                  widget.buildIndex == 0
+                      ? '先听词块，再逐步合成整句。'
+                      : widget.chunks.take(widget.buildIndex).join(' '),
+                ),
+                TextButton.icon(
+                  onPressed: () async {
+                    final next = widget.buildIndex < widget.chunks.length
+                        ? widget.buildIndex + 1
+                        : 1;
+                    await VoiceService.instance.speak(
+                      widget.chunks.take(next).join(' '),
+                    );
+                    widget.onBuildProgress(next);
+                  },
+                  icon: const Icon(Icons.play_arrow),
+                  label: Text(
+                    widget.buildIndex == widget.chunks.length
+                        ? '从头再练'
+                        : '听下一段并跟读',
+                  ),
+                ),
+              ],
+            ),
+          ),
+        if (widget.examples.isNotEmpty)
+          ExpansionTile(
+            title: Text('更多示范句（${widget.examples.length}）'),
+            children: [
+              for (final example in widget.examples)
+                ListTile(
+                  title: LexiconText(example, state: widget.state),
+                  trailing: IconButton(
+                    tooltip: '播放示范句',
+                    icon: const Icon(Icons.volume_up_outlined),
+                    onPressed: () => VoiceService.instance.speak(example),
+                  ),
+                ),
+            ],
+          ),
         SecondaryButton(
           label: transcribing
               ? '正在 AI 识别发音…'
@@ -146,8 +199,10 @@ class _SpeakingStepState extends State<_SpeakingStep>
           ),
         ),
         PrimaryButton(
-          label: transcript.isEmpty ? '我已跟读，继续' : '确认并继续',
-          onPressed: widget.onContinue,
+          label: recordingPath == null ? '跳过跟读，继续' : '录音完成，继续',
+          onPressed: (listening || transcribing)
+              ? null
+              : () => widget.onContinue(recordingPath != null),
         ),
       ],
     ),