add merging sentences action

sentence_api/static/admin.js

@@ -254,7 +254,7 @@ async function openSentences(video) {
     elements.sentenceMeta.textContent = `${sentences.length} 句 / ${detail.video.video_hash}`;
     elements.sentenceRows.replaceChildren();
     for (const sentence of sentences) {
-      elements.sentenceRows.append(sentenceRow(video, sentence));
+      elements.sentenceRows.append(sentenceRow(video, sentence, sentences.length));
     }
     if (!elements.dialog.open) elements.dialog.showModal();
   } catch (error) {
@@ -262,7 +262,7 @@ async function openSentences(video) {
   }
 }
 
-function sentenceRow(video, sentence) {
+function sentenceRow(video, sentence, totalCount) {
   const row = document.createElement("tr");
   const textArea = document.createElement("textarea");
   textArea.value = sentence.text || "";
@@ -307,6 +307,26 @@ function sentenceRow(video, sentence) {
     }
   });
   saveContainer.append(save);
+  if (sentence.index < totalCount - 1) {
+    const merge = button("合并下句", async () => {
+      const preview = `${(textArea.value || sentence.text || "").trim()} + 下一句`;
+      const confirmed = window.confirm(`确定将第 ${sentence.index + 1} 句与下一句合并成一句吗？\n${preview}`);
+      if (!confirmed) return;
+      merge.disabled = true;
+      try {
+        await api(`/api/v1/admin/videos/${video.video_hash}/sentences/${sentence.index}/merge`, {
+          method: "PUT",
+        });
+        merge.textContent = "已合并";
+        await openSentences(video);
+      } catch (error) {
+        elements.serviceState.textContent = `句子合并失败: ${error.message}`;
+        merge.textContent = error.message;
+        window.setTimeout(() => { merge.disabled = false; merge.textContent = "合并下句"; }, 1600);
+      }
+    });
+    saveContainer.append(merge);
+  }
   const timeContainer = document.createElement("td");
   const startLabel = document.createElement("span");
   startLabel.textContent = formatDuration(sentence.start_ms);