feat: 深度研究支持独立新报告与原文改写，并完善沙箱、模型管理与全文改写

新报告不再覆盖当前文件卡片，写入时打开沙箱；步骤条仅在改写原文时位于卡片上方。同时补齐改写本地回退、模型管理与会商第三步相关改动。

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

frontend-web/src/core/artifacts/loader.ts

@@ -46,7 +46,7 @@ export async function loadArtifactContent({
   return { content: text, url };
 }
 
-export function loadArtifactContentFromToolCall({
+export function loadArtifactContentFromToolCall({
   url: urlString,
   thread,
 }: {
@@ -66,5 +66,58 @@ export function loadArtifactContentFromToolCall({
         return toolCall.args.content;
       }
     }
-  }
-}
+  }
+}
+
+function normalizeArtifactPath(path: string): string {
+  let normalized = path.trim();
+  const first = normalized[0];
+  const last = normalized.at(-1);
+  if (
+    normalized.length >= 2 &&
+    ((first === '"' && last === '"') ||
+      (first === "'" && last === "'") ||
+      (first === "`" && last === "`"))
+  ) {
+    normalized = normalized.slice(1, -1).trim();
+  }
+  return normalized.replace(/\\/g, "/").replace(/^\/+/, "");
+}
+
+/**
+ * Last-resort preview for an output whose artifact HTTP request is unavailable.
+ *
+ * A completed `write_file` can be selected before its backing sandbox file is
+ * visible through the artifacts endpoint (or when a deployment temporarily
+ * serves a stale mount).  The original tool arguments still contain the
+ * Markdown, so use the newest matching write as a read-only display fallback.
+ */
+export function loadArtifactContentFromLatestWriteFile({
+  filepath,
+  thread,
+}: {
+  filepath: string;
+  thread: BaseStream<AgentThreadState>;
+}): string | undefined {
+  const normalizedFilepath = normalizeArtifactPath(filepath);
+  if (!normalizedFilepath) return undefined;
+
+  for (const message of [...thread.messages].reverse()) {
+    if (message.type !== "ai" || !message.tool_calls) continue;
+    for (const toolCall of [...message.tool_calls].reverse()) {
+      if (toolCall.name !== "write_file") continue;
+      if (!toolCall.args || typeof toolCall.args !== "object" || Array.isArray(toolCall.args)) {
+        continue;
+      }
+      const args = toolCall.args as { path?: unknown; content?: unknown };
+      if (
+        typeof args.path === "string" &&
+        typeof args.content === "string" &&
+        normalizeArtifactPath(args.path) === normalizedFilepath
+      ) {
+        return args.content;
+      }
+    }
+  }
+  return undefined;
+}