feat: add session-scoped client tool waits

backend/services/tool_policy.py

@@ -19,6 +19,7 @@ class ToolRuntimePolicy:
     allow_interruptions: bool
     execution_mode: str
     wait_for_response: bool
+    response_wait_mode: str
 
     @property
     def cancel_on_interruption(self) -> bool:
@@ -38,8 +39,12 @@ def policy_for_tool(tool: RuntimeTool) -> ToolRuntimePolicy:
     mode = str(config.get("execution_mode") or default_mode)
     if mode not in {"immediate", "async"}:
         mode = default_mode
+    response_wait_mode = str(config.get("response_wait_mode") or "timeout")
+    if response_wait_mode not in {"timeout", "session"}:
+        response_wait_mode = "timeout"
     return ToolRuntimePolicy(
         allow_interruptions=bool(config.get("allow_interruptions", True)),
         execution_mode=mode,
         wait_for_response=bool(config.get("wait_for_response", True)),
+        response_wait_mode=response_wait_mode,
     )