fix(followup-audio): preserve roles chosen before first audio file

admin/src/views/tcm/diagnosis/components/FollowupAudioPanel.vue

@@ -59,6 +59,7 @@
             <section v-if="hasStereo" class="channel-role-box" aria-label="声道角色人工标注">
                 <label>声道角色（人工确认）<el-select :model-value="channelRoles" :disabled="!canEditReview || busy" @update:model-value="setChannelRoles"><el-option label="角色待确认" value="unconfirmed" /><el-option label="左客服端 / 右患者或家属端" value="left_service" /><el-option label="右客服端 / 左患者或家属端" value="right_service" /></el-select></label>
                 <p class="muted">声道不等于已核实的说话人身份。角色标注不自动重新提炼；变更后保存草稿会取消全部采纳，须重新核对。</p>
+                <p v-if="savedChannelRoles !== 'unconfirmed' && !roleDirty" class="muted">当前角色已确认，无需再次选择；只有左右标错时才需修改。</p>
                 <p v-if="roleDirty" class="review-error" role="status">角色标注尚未保存，请先保存草稿，再逐项核对。</p>
             </section>
             <FollowupAudioReview :key="selectedId" ref="reviewRef" v-model:items="reviewItems" :fields="detail.fields || capabilities.fields" :disabled="!canEditReview || busy" :can-daily="capabilities.can_daily" :applied="detail.status === 'applied'" :uncertainties="detail.uncertainties" :snapshot-items="detail.items" :channel-roles="savedChannelRoles" @seek="loadDialogue" />
@@ -292,7 +293,11 @@ async function backToList() {
     stop(); resetRoles(); selectedId.value = 0; detail.value = null; reviewItems.value = []; snapshot.value = '[]'; detailSections.value = []; errorMessage.value = ''
     await refresh()
 }
-function openUpload() { if (canUpload.value && !busy.value && !createUncertain.value) uploadVisible.value = true }
+function openUpload() {
+    if (!canUpload.value || busy.value || createUncertain.value) return
+    if (!file.value) uploadChannelRoles.value = 'unconfirmed'
+    uploadVisible.value = true
+}
 function closeUpload(done?: () => void) { if (uploading.value) return; uploadVisible.value = false; done?.() }
 function statusType(status: string) {
     if (status === 'failed' || status === 'needs_reconciliation') return 'danger'
@@ -300,7 +305,16 @@ function statusType(status: string) {
     if (status === 'review') return 'warning'
     return 'info'
 }
-function chooseFile(event: Event) { uploadChannelRoles.value = 'unconfirmed'; file.value = (event.target as HTMLInputElement).files?.[0] || null; uploadProgress.value = 0; uploadStage.value = '' }
+function chooseFile(event: Event) {
+    const nextFile = (event.target as HTMLInputElement).files?.[0] || null
+    // Cancelling the picker or selecting the first file must not discard a role chosen earlier.
+    if (!nextFile) return
+    if (file.value && nextFile !== file.value) {
+        uploadChannelRoles.value = 'unconfirmed'
+        ElMessage.warning('录音已更换，请重新核对本次录音的声道角色')
+    }
+    file.value = nextFile; uploadProgress.value = 0; uploadStage.value = ''
+}
 async function submitUpload() {
     if (busy.value || createUncertain.value) return
     const problem = uploadIssue(file.value, recordedAt.value, modelKey.value, props.capabilities, props.viewOnly)