fix(paper): 确认大纲后即时 seed 进度卡并逐节刷新

- 后端写稿循环不再落空 paper_progress 块（重载后出现空卡），改落开始撰写文本
- 前端 confirmPaper 时用大纲节标题本地 seed 进度卡，2s 轮询 patch 逐节状态
- 当前节按 current_section_id 标 writing（…动画）

sdk/app/services/paper/agent.py

@@ -232,9 +232,9 @@ async def run_writing_loop(db, paper_id: str, session_id: str) -> None:
     from ...routers.docgen import insert_artifact  # 惰性导入，避免服务层→路由层常驻耦合
 
     client = _new_client()
-    await _write_message(db, session_id, blocks=[
-        {"type": "paper_progress", "paper_id": paper_id, "status": "writing", "sections": [], "current_section_id": ""},
-    ], text="开始撰写")
+    # 进度卡由前端确认时本地 seed + 2s 轮询 get_paper_progress 驱动（不落库，避免重载后出现
+    # 空的「撰写中」卡）；后端只落「开始撰写」文本 + 逐节完成小结 + 最终 artifact。
+    await _write_message(db, session_id, blocks=[_text_block("开始逐节撰写……")], text="开始撰写")
     try:
         while True:
             prog = await client.call_tool("get_paper_progress", {"paper_id": paper_id})

tests/paper/test_paper_bff_agent.py

@@ -118,6 +118,7 @@ def test_writing_loop_completes_to_artifact(bff_database, monkeypatch, fake_inse
 
     assert svc.s1_done and svc.s2_done
     rows = _run(bff_database.fetchall("SELECT * FROM messages WHERE session_id = 's1' ORDER BY rowid"))
-    assert "paper_progress" in rows[0]["blocks"]
+    # 进度卡由前端确认时本地 seed + 轮询驱动，后端只落「开始撰写」文本 + 逐节小结 + artifact
+    assert "开始逐节撰写" in rows[0]["blocks"]
     assert "artifact" in rows[-1]["blocks"]
     assert "art-fake" in rows[-1]["blocks"]

ui/src/stores/chat.js

@@ -1658,16 +1658,47 @@ export const useChatStore = defineStore('chat', {
       this.scrollSeq++;
     },
 
-    /** 确认大纲 → POST confirm 启动后台写节循环 → 2s 轮询进度 */
+    /** 确认大纲 → 本地先 seed 进度卡 → POST confirm 启动后台写节循环 → 2s 轮询进度 */
     async confirmPaper(paperId) {
       const sessionId = this.sessionId;
       if (!paperId || !sessionId) return;
+      this._seedPaperProgress(sessionId, paperId);
       try {
         await confirmPaperApi(paperId, sessionId);
       } catch { /* 启动失败：卡片可见错误 */ }
       this._startPaperPoll(paperId, sessionId);
     },
 
+    /** 确认后立即在消息流上一条 paper_progress 块（用大纲节标题做种子，全部 pending），
+     *  使 _startPaperPoll 的 _patchPaperProgress 有块可 patch，进度卡在撰写期间逐节刷新，
+     *  而不是等 complete 重载时一次性出现。 */
+    _seedPaperProgress(sessionId, paperId) {
+      const list = this.sessionMsgs[sessionId] || this.messages || [];
+      for (const m of list) {
+        if (!m || m.role !== 'assistant' || !Array.isArray(m.blocks)) continue;
+        if (m.blocks.some((b) => b && b.type === 'paper_progress' && b.paper_id === paperId)) return;
+      }
+      let sections = [];
+      for (let i = list.length - 1; i >= 0; i--) {
+        const m = list[i];
+        if (!m || m.role !== 'assistant' || !Array.isArray(m.blocks)) continue;
+        const ob = m.blocks.find((b) => b && b.type === 'paper_outline' && b.paper_id === paperId);
+        if (ob) {
+          sections = (Array.isArray(ob.sections) ? ob.sections : []).map((sec) => ({
+            section_id: sec.section_id, title: sec.title || '', status: 'pending',
+          }));
+          break;
+        }
+      }
+      const raw = {
+        id: null, role: 'assistant', kind: 'paper', status: 'done', text: null,
+        blocks: [{ type: 'paper_progress', paper_id: paperId, status: 'writing', sections, current_section_id: '' }],
+        raw: null, created_at: new Date().toISOString(), updated_at: new Date().toISOString(),
+      };
+      list.push(raw);
+      this.scrollSeq++;
+    },
+
     _startPaperPoll(paperId, sessionId) {
       if (paperPolls.has(paperId)) return;
       const entry = { timer: null, sessionId };
@@ -1706,13 +1737,18 @@ export const useChatStore = defineStore('chat', {
     /** 把进度同步进消息流里的 paper_progress 块 */
     _patchPaperProgress(sessionId, prog) {
       const list = this.sessionMsgs[sessionId] || [];
+      const current = prog.current_section_id || '';
       for (const m of list) {
         if (!m || m.role !== 'assistant' || !Array.isArray(m.blocks)) continue;
         const pb = m.blocks.find((b) => b && b.type === 'paper_progress');
         if (pb) {
           pb.status = prog.status;
-          pb.current_section_id = prog.current_section_id || '';
-          pb.sections = (prog.sections || []).map((s) => ({ section_id: s.section_id, title: s.title, status: s.status }));
+          pb.current_section_id = current;
+          // 后端节状态只有 pending/done；当前节用 current_section_id 标为 writing（…动画）
+          pb.sections = (prog.sections || []).map((sec) => ({
+            section_id: sec.section_id, title: sec.title,
+            status: (current && sec.section_id === current) ? 'writing' : sec.status,
+          }));
         }
       }
       this.scrollSeq++;