fix(mobile): handle file picker cancellation

mobile-uni/src/pages/user/practice/index.vue

@@ -532,6 +532,7 @@ import { createPageRequestScope, currentAccountKey, type RequestScopeTicket } fr
 import { createRealtimePracticeController, createRealtimeSession, fetchRealtimePersonas, invokeRealtimeTool, type RealtimePersonaOption } from '@/services/realtime-practice';
 import { stripInternalCodes } from '@/services/text';
 import { describeMicrophoneError, microphoneDeniedMessage, requestMicrophonePermission } from '@/utils/microphone';
+import { isFileSelectionCancelled } from '@/utils/file-selection';
 import { safeTopPadding } from '@/utils/safe-area';
 
 type PracticeStatus = 'idle' | 'starting' | 'active' | 'submitting' | 'finished';
@@ -913,8 +914,10 @@ const composerPickAudio = async () => {
     await submitTranscribed(text, asr.audioUrl || '', normalizeOssId(asr.ossId));
   } catch (error) {
     if (generation !== transcriptionGeneration) return;
-    const text = error instanceof Error ? error.message : '语音转写失败，请改用文字输入';
-    if (text !== '未选择音频') uni.showToast({ title: text, icon: 'none' });
+    if (!isFileSelectionCancelled(error)) {
+      const text = error instanceof Error ? error.message : '语音转写失败，请改用文字输入';
+      uni.showToast({ title: text, icon: 'none' });
+    }
   } finally {
     if (generation === transcriptionGeneration) {
       abortTranscription = null;
@@ -1226,6 +1229,10 @@ const transcribeCapture = async (capture: SpeechCapture, assignmentId?: number)
     }
   } catch (error) {
     if (generation !== transcriptionGeneration) return;
+    if (isFileSelectionCancelled(error)) {
+      message.value = '';
+      return;
+    }
     handleError(error, '语音转写失败');
   } finally {
     if (generation === transcriptionGeneration) {