diff --git a/apps/axon_agent/src/process_manager.cpp b/apps/axon_agent/src/process_manager.cpp
index ae0d7671..a8e3bbc1 100644
--- a/apps/axon_agent/src/process_manager.cpp
+++ b/apps/axon_agent/src/process_manager.cpp
@@ -88,6 +88,10 @@ bool parse_http_url(const std::string& url, HttpUrl* output, std::string* error)
   return true;
 }
 
+std::filesystem::path default_transient_log_dir() {
+  return std::filesystem::path("/tmp") / "axon-agent" / "logs";
+}
+
 }  // namespace
 
 ProcessManager::ProcessManager(std::filesystem::path state_dir)
@@ -794,7 +798,7 @@ std::filesystem::path ProcessManager::default_log_file(
 ) const {
   const auto pid_file =
     config.pid_file.empty() ? default_pid_file(config.process_id) : config.pid_file;
-  return state_dir_ / "logs" / (pid_file.stem().string() + "." + stream + ".log");
+  return default_transient_log_dir() / (pid_file.stem().string() + "." + stream + ".log");
 }
 
 }  // namespace agent
diff --git a/apps/axon_agent/test/test_agent_service.cpp b/apps/axon_agent/test/test_agent_service.cpp
index ab79f1a7..146d5fe2 100644
--- a/apps/axon_agent/test/test_agent_service.cpp
+++ b/apps/axon_agent/test/test_agent_service.cpp
@@ -140,6 +140,18 @@ auto_start: false
       recorder["health_check"]["timeout_ms"].get<int>() == 250, "recorder health timeout mismatch"
     );
 
+    const auto& transfer = processes["transfer"];
+    require(
+      transfer["stdout_log"].get<std::string>() ==
+        (std::filesystem::path("/tmp/axon-agent/logs") / "demo_robot_transfer.stdout.log").string(),
+      "transfer default stdout_log mismatch"
+    );
+    require(
+      transfer["stderr_log"].get<std::string>() ==
+        (std::filesystem::path("/tmp/axon-agent/logs") / "demo_robot_transfer.stderr.log").string(),
+      "transfer default stderr_log mismatch"
+    );
+
     const auto& robot = processes["robot_startup"];
     require(
       robot["working_directory"].get<std::string>() == (profile_dir / "runtime").string(),
diff --git a/docs/designs/axon-agent-design.md b/docs/designs/axon-agent-design.md
index bcef4a50..07790a4e 100644
--- a/docs/designs/axon-agent-design.md
+++ b/docs/designs/axon-agent-design.md
@@ -112,7 +112,7 @@ process:
     timeout_ms: 500
 ```
 
-`adapter.yaml` 下的 `managed_processes.<process_id>` 使用同一组字段。`working_directory` 的相对路径按 profile 根目录解析；`pid_file`、`metadata_file`、`stdout_log`、`stderr_log` 的相对路径按 agent `state_dir` 解析。未配置 `pid_file`、`metadata_file` 和日志路径时，agent 会自动按 `profile_id + process_id` 生成隔离路径。
+`adapter.yaml` 下的 `managed_processes.<process_id>` 使用同一组字段。`working_directory` 的相对路径按 profile 根目录解析；`pid_file`、`metadata_file`、`stdout_log`、`stderr_log` 的相对路径按 agent `state_dir` 解析。未配置 `pid_file`、`metadata_file` 时，agent 会自动按 `profile_id + process_id` 生成隔离路径；未配置日志路径时，stdout/stderr 默认保存到 `/tmp/axon-agent/logs/<profile_id>_<process_id>.<stdout|stderr>.log`，避免一次性子进程日志长期积累在持久 state 目录。
 
 `health_check.type` 首版支持 `process`、`http`、`none`。`process` 只检查被管理进程 pid 是否仍在运行；`http` 支持 `url`、`timeout_ms` 和 `expected_status`，用于 recorder/transfer 等带本地 HTTP 端口的组件；`none` 用于明确关闭健康检查。
 
diff --git a/packaging/deb/agent/default/axon-agent b/packaging/deb/agent/default/axon-agent
index 9f7c1029..1fdbe930 100644
--- a/packaging/deb/agent/default/axon-agent
+++ b/packaging/deb/agent/default/axon-agent
@@ -9,5 +9,7 @@ AXON_AGENT_PORT=8090
 # contain adapter.yaml and optional recorder.yaml / transfer.yaml files.
 AXON_AGENT_PROFILE_PATH=/opt/axon/robots
 
-# Runtime state, active_profile.json, child pid files, metadata, and logs.
+# Runtime state, active_profile.json, child pid files, and metadata.
+# Managed process stdout/stderr defaults to /tmp/axon-agent/logs unless a
+# profile explicitly sets stdout_log/stderr_log.
 AXON_AGENT_STATE_DIR=/var/lib/axon/agent