rehearsal: test stub create_thread accepts instructions (main-side dispatch interface; 2 host errors fixed, no production change)

tests/test_host_coverage85_2.py

@@ -104,7 +104,11 @@ class StubServer:
         self.created = []
 
     def create_thread(self, cwd, model=None, sandbox=None,
-                      approval_policy=None):
+                      approval_policy=None, instructions=None):
+        # 演练注：main 侧 dispatch 传 instructions（developer
+        # 指令，真实 Server.create_thread 已接受）；源线 stub
+        # 未跟进接口致 2 项 TypeError，测试桩同步接口，生产
+        # 代码与断言均未动。
         self.created.append(cwd)
         return "th-1"