仅在有快照或检查点时允许重出一版。

避免无上下文可复用时误点重跑。

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

src/server/message-branch.ts

@@ -215,6 +215,23 @@ export function isRefreshableMessage(msg: BranchableMessage): boolean {
   return kind === "worker_questions" || kind === "worker_output";
 }
 
+/** 与 refreshMessage 同一套门槛：类型对，且有 worker 快照或该条检查点。 */
+export function canAttemptRefresh(
+  msg: BranchableMessage,
+  opts: {
+    lastWorkerId?: string;
+    hasLastWorkerSnapshot: boolean;
+    hasMessageCheckpoint: boolean;
+  },
+): boolean {
+  if (!isRefreshableMessage(msg)) return false;
+  const workerId =
+    (typeof msg.actor === "string" && msg.actor.trim()) ||
+    opts.lastWorkerId?.trim();
+  if (!workerId) return false;
+  return opts.hasMessageCheckpoint || opts.hasLastWorkerSnapshot;
+}
+
 export function findPrecedingUserIndex(messages: BranchableMessage[], fromIndex: number): number {
   for (let i = fromIndex - 1; i >= 0; i--) {
     if (messages[i].role === "user") return i;

tests/message-branch.test.ts

@@ -5,6 +5,8 @@ import {
   ensureBranchForEdit,
   recordPreMessageCheckpoint,
   switchBranchVariant,
+  canAttemptRefresh,
+  isRefreshableMessage,
 } from "../src/server/message-branch.js";
 import { createSession } from "../src/runtime/phase-machine.js";
 
@@ -62,3 +64,61 @@ describe("message-branch", () => {
     expect(branch.variants[0].messages[0].text).toBe("首句");
   });
 });
+
+describe("canAttemptRefresh", () => {
+  const output = {
+    id: "w1",
+    role: "system" as const,
+    text: "场面",
+    createdAt: "1",
+    kind: "worker_output",
+    actor: "world-simulator",
+  };
+
+  it("rejects user bubbles", () => {
+    expect(
+      isRefreshableMessage({
+        id: "u1",
+        role: "user",
+        text: "行动",
+        createdAt: "1",
+        kind: "user_input",
+      }),
+    ).toBe(false);
+    expect(
+      canAttemptRefresh(
+        {
+          id: "u1",
+          role: "user",
+          text: "行动",
+          createdAt: "1",
+          kind: "user_input",
+        },
+        {
+          lastWorkerId: "world-simulator",
+          hasLastWorkerSnapshot: true,
+          hasMessageCheckpoint: true,
+        },
+      ),
+    ).toBe(false);
+  });
+
+  it("allows worker output when a snapshot exists", () => {
+    expect(
+      canAttemptRefresh(output, {
+        lastWorkerId: "world-simulator",
+        hasLastWorkerSnapshot: true,
+        hasMessageCheckpoint: false,
+      }),
+    ).toBe(true);
+  });
+
+  it("rejects worker output with no snapshot and no checkpoint", () => {
+    expect(
+      canAttemptRefresh(output, {
+        hasLastWorkerSnapshot: false,
+        hasMessageCheckpoint: false,
+      }),
+    ).toBe(false);
+  });
+});