fix: writing mode uses chat search then pipeline write only

Keep deep_research_report as a write-only deliverable from conversation materials, block post-success rewrite loops with a summary nudge, fill thin/empty pools from model knowledge, and open the sandbox only on real report.md content.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-web/src/pages/AgentChatPage.tsx

@@ -45,6 +45,7 @@ import { stopActiveThreadBeforeClarificationReply, stopThreadRun, useThreadStrea
 import { useResearchWritingFeed } from "@/core/threads/use-research-writing-feed";
 import { clearResearchReportStream } from "@/core/threads/use-research-report-stream";
 import { textOfMessage } from "@/core/threads/utils";
+import { resolveWritingModeReportPath } from "@/core/threads/writing-mode";
 import { OptType, writeYLog } from "@/core/log/y-log";
 import {
   Select,
@@ -612,16 +613,13 @@ export default function AgentChatPage({
     } as typeof displayThread;
   }, [displayThread, showReportImportCard, taskId, threadId]);
 
-  // 写作模式续写轮：已有 md 产物（report.md 已生成）时回传 writing_artifact_path，
-  // 后端据此走「直接编辑画布」分支而不是再次挂载深度研究写报告管线（与
-  // ChatPage 的回传逻辑对齐）。
-  const writingArtifactPath = useMemo(() => {
-    const isMarkdown = (path: string | null | undefined) =>
-      !!path && /\.(md|markdown)(?:$|[?#])/i.test(path);
-    return [...(thread.values.artifacts ?? [])]
-      .reverse()
-      .find((path) => isMarkdown(path));
-  }, [thread.values.artifacts]);
+  // 写作模式续写轮：仅当已有写作模式产物 report.md 时回传 writing_artifact_path，
+  // 后端据此走「直接编辑画布」分支而不是再次挂载深度研究写报告管线。其它 leftover
+  // .md 不得跳过管线（与 ChatPage 对齐）。
+  const writingArtifactPath = useMemo(
+    () => resolveWritingModeReportPath(thread.values.artifacts),
+    [thread.values.artifacts],
+  );
 
   // ── 「模板数据转换器」对话页专属调试入口（仅此 agent）──────────────────────────
   // 选一个页面模板，问答跑完后点「渲染预览」：取最近一条 AI 回复里的 JSON 填进模板，

frontend-web/src/pages/ChatPage.tsx

@@ -63,6 +63,7 @@ import {
 import { useThreadStream, stopActiveThreadBeforeClarificationReply } from "@/core/threads/hooks";
 import { useResearchWritingFeed } from "@/core/threads/use-research-writing-feed";
 import { clearResearchReportStream } from "@/core/threads/use-research-report-stream";
+import { resolveWritingModeReportPath } from "@/core/threads/writing-mode";
 import { queueLlmWikiConversationDeposit } from "@/core/llmwiki/conversation-deposit";
 import { useSingleRoundRagMessages } from "@/core/threads/use-single-round-rag";
 import { useMultiRoundRagMessages } from "@/core/threads/use-multi-round-rag";
@@ -354,16 +355,11 @@ export default function ChatPage() {
     researchDisplayThread,
   ]);
 
-  const writingArtifactPath = useMemo(() => {
-    const isMarkdown = (path: string | null | undefined) =>
-      !!path && /\.(md|markdown)(?:$|[?#])/i.test(path);
-    if (isMarkdown(selectedArtifact)) {
-      return selectedArtifact ?? undefined;
-    }
-    return [...(thread.values.artifacts ?? [])]
-      .reverse()
-      .find((path) => isMarkdown(path));
-  }, [selectedArtifact, thread.values.artifacts]);
+  const writingArtifactPath = useMemo(
+    () =>
+      resolveWritingModeReportPath(thread.values.artifacts, selectedArtifact),
+    [selectedArtifact, thread.values.artifacts],
+  );
 
   const handleSubmit = useCallback(
     (message: PromptInputMessage) => {

frontend-web/src/pages/IframeChatPage.tsx

@@ -42,6 +42,7 @@ import {
 import { usePluginManagementSettings } from "@/core/system-settings/hooks";
 import { stopActiveThreadBeforeClarificationReply, useThreadStream } from "@/core/threads/hooks";
 import { textOfMessage } from "@/core/threads/utils";
+import { resolveWritingModeReportPath } from "@/core/threads/writing-mode";
 import { env } from "@/env";
 import { cn } from "@/lib/utils";
 import {
@@ -285,16 +286,11 @@ export default function IframeChatPage() {
     threadMetadataAgentId,
   ]);
 
-  const writingArtifactPath = useMemo(() => {
-    const isMarkdown = (path: string | null | undefined) =>
-      !!path && /\.(md|markdown)(?:$|[?#])/i.test(path);
-    if (isMarkdown(selectedArtifact)) {
-      return selectedArtifact ?? undefined;
-    }
-    return [...(thread.values.artifacts ?? [])]
-      .reverse()
-      .find((path) => isMarkdown(path));
-  }, [selectedArtifact, thread.values.artifacts]);
+  const writingArtifactPath = useMemo(
+    () =>
+      resolveWritingModeReportPath(thread.values.artifacts, selectedArtifact),
+    [selectedArtifact, thread.values.artifacts],
+  );
 
   const handleSubmit = useCallback(
     (