diff --git a/templates/index.html b/templates/index.html
index 8af0b6b..07eaa1d 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -3641,10 +3641,7 @@
             reportTaskId = null;
 
             // 停止可能正在进行的轮询
-            if (reportPollingInterval) {
-                clearInterval(reportPollingInterval);
-                reportPollingInterval = null;
-            }
+            stopProgressPolling();
 
             // 向所有运行中的应用发送搜索请求（通过刷新iframe传递参数）
             let totalRunning = 0;
@@ -5268,10 +5265,11 @@
                     resetReportLogsForNewTask(taskId, '检测到正在运行的报告任务，日志已重新开始');
                     reportTaskId = taskId;
                     reportAutoPreviewLoaded = false;
+                    startProgressPolling(taskId);
                     if (window.EventSource) {
                         openReportStream(reportTaskId);
                     } else {
-                        startProgressPolling(taskId);
+                        appendReportStreamLine('浏览器不支持SSE，已切换为轮询模式', 'warn', { badge: 'SSE', force: true });
                     }
                 } else if (statusData.current_task.status === 'completed') {
                     lastCompletedReportTask = statusData.current_task;
@@ -5346,13 +5344,25 @@
             const downloadPdfButton = document.getElementById('downloadPdfButton');
             if (!downloadButton || !downloadPdfButton) return;
 
-            if (task && task.status === 'completed' && (task.report_file_ready || task.report_file_path)) {
+            const htmlReady = task && task.status === 'completed' && (
+                task.report_file_ready ||
+                task.report_file_path ||
+                task.has_result // 有内容即可允许尝试下载/预览
+            );
+            const pdfReady = task && task.status === 'completed' && (
+                task.ir_file_ready ||
+                task.ir_file_path ||
+                task.report_file_ready ||
+                task.report_file_path
+            );
+
+            if (htmlReady) {
                 downloadButton.disabled = false;
                 downloadButton.dataset.taskId = task.task_id;
                 downloadButton.dataset.filename = task.report_file_name || '';
                 const label = task.report_file_name ? `下载HTML (${task.report_file_name})` : '下载HTML';
                 downloadButton.textContent = label;
-                downloadPdfButton.disabled = false;
+                downloadPdfButton.disabled = !pdfReady;
                 downloadPdfButton.dataset.taskId = task.task_id;
                 lastCompletedReportTask = task;
             } else if (!lastCompletedReportTask || (task && task.status !== 'completed')) {
@@ -5631,10 +5641,13 @@
                     // 确保从任务开始就能读取日志
                     reportLogManager.start();
 
+                    // 【兜底】立即启动进度轮询，SSE连上后会自动停止
+                    startProgressPolling(reportTaskId);
+
                     if (window.EventSource) {
                         openReportStream(reportTaskId);
                     } else {
-                        startProgressPolling(data.task_id);
+                        appendReportStreamLine('浏览器不支持SSE，已切换为轮询模式', 'warn', { badge: 'SSE', force: true });
                     }
                 } else {
                     updateTaskProgressStatus(null, 'error', '启动失败: ' + data.error);
@@ -5664,12 +5677,19 @@
         // 【新函数】使用新的日志管理器
         // 旧的startReportLogRefresh和stopReportLogRefresh已废弃，请使用reportLogManager
 
-        // 开始进度轮询
-        function startProgressPolling(taskId) {
+        // 开始/停止进度轮询（SSE不可用或断开时兜底使用）
+        function stopProgressPolling() {
             if (reportPollingInterval) {
                 clearInterval(reportPollingInterval);
+                reportPollingInterval = null;
             }
+        }
 
+        function startProgressPolling(taskId) {
+            if (!taskId) return;
+            stopProgressPolling();
+            // 先立即拉取一次，避免长时间停留在5%
+            checkTaskProgress(taskId);
             reportPollingInterval = setInterval(() => {
                 checkTaskProgress(taskId);
             }, 2000);
@@ -5687,7 +5707,7 @@
                     // reportLogManager会自动处理轮询
 
                     if (data.task.status === 'completed') {
-                        clearInterval(reportPollingInterval);
+                        stopProgressPolling();
                         showMessage('报告生成完成！', 'success');
                         
                         // 自动显示报告
@@ -5699,7 +5719,7 @@
                         reportTaskId = null;
                         setGenerateButtonState(false);
                     } else if (data.task.status === 'error') {
-                        clearInterval(reportPollingInterval);
+                        stopProgressPolling();
                         showMessage('报告生成失败: ' + data.task.error_message, 'error');
                         
                         // 重置自动生成标志，允许重新尝试
@@ -5863,10 +5883,6 @@
                 startProgressPolling(taskId);
                 return;
             }
-            if (reportPollingInterval) {
-                clearInterval(reportPollingInterval);
-                reportPollingInterval = null;
-            }
             if (reportEventSource && reportEventSource.__taskId === taskId) {
                 if (reportEventSource.readyState !== EventSource.CLOSED) {
                     return;
@@ -5913,6 +5929,7 @@
                 if (reportTaskId) {
                     reportLogManager.start();
                 }
+                startProgressPolling(taskId);
                 scheduleReportStreamReconnect(taskId);
             };
 
@@ -6060,6 +6077,7 @@
                     break;
                 case 'completed':
                     appendReportStreamLine(payload.message || '任务完成', 'success');
+                    stopProgressPolling();
 
                     // 【修复】任务完成前强制刷新最后一次日志，确保所有日志都被读取
                     if (reportLogManager && reportLogManager.isRunning) {
@@ -6084,6 +6102,7 @@
                     break;
                 case 'cancelled':
                     appendReportStreamLine(payload.message || '任务已取消', 'warn');
+                    stopProgressPolling();
                     safeCloseReportStream();
                     updateReportStreamStatus('idle');
                     reportTaskId = null;
@@ -6091,6 +6110,7 @@
                     break;
                 case 'error':
                     appendReportStreamLine(payload.message || '任务失败', 'error', { badge: 'ERROR' });
+                    stopProgressPolling();
                     safeCloseReportStream();
                     updateReportStreamStatus('error');
                     reportTaskId = null;