diff --git a/astrbot/core/tools/computer_tools/shell.py b/astrbot/core/tools/computer_tools/shell.py
index a6d44c221..1e1acfbf9 100644
--- a/astrbot/core/tools/computer_tools/shell.py
+++ b/astrbot/core/tools/computer_tools/shell.py
@@ -105,8 +105,11 @@ class ExecuteShellTool(FunctionTool):
                 current_workspace_root.mkdir(parents=True, exist_ok=True)
                 cwd = str(current_workspace_root)
 
+            env = dict(env or {})
+            effective_background = background and not _is_self_detached_command(command)
+
             stdout_file: str | None = None
-            if background:
+            if effective_background:
                 local_runtime = is_local_runtime(context)
                 stdout_file = _build_background_output_path(
                     local_runtime=local_runtime,
@@ -117,8 +120,6 @@ class ExecuteShellTool(FunctionTool):
                     local_runtime=local_runtime,
                 )
 
-            env = dict(env or {})
-            effective_background = background and not _is_self_detached_command(command)
             result = await sb.shell.exec(
                 command,
                 cwd=cwd,
diff --git a/tests/unit/test_func_tool_manager.py b/tests/unit/test_func_tool_manager.py
index 4eae43b5c..d53ed3296 100644
--- a/tests/unit/test_func_tool_manager.py
+++ b/tests/unit/test_func_tool_manager.py
@@ -56,7 +56,9 @@ async def test_execute_shell_defaults_to_foreground(monkeypatch):
     calls = []
 
     class FakeShell:
-        async def exec(self, command, cwd=None, background=False, env=None):
+        async def exec(
+            self, command, cwd=None, background=False, env=None, timeout=None
+        ):
             calls.append({"command": command, "background": background})
             return {"success": True, "stdout": "", "stderr": "", "exit_code": 0}
 
@@ -98,7 +100,9 @@ async def test_execute_shell_uses_fresh_default_env_per_call(monkeypatch):
     calls = []
 
     class FakeShell:
-        async def exec(self, command, cwd=None, background=False, env=None):
+        async def exec(
+            self, command, cwd=None, background=False, env=None, timeout=None
+        ):
             env["MUTATED_BY_FAKE_SHELL"] = command
             calls.append(env)
             return {"success": True, "stdout": "", "stderr": "", "exit_code": 0}
@@ -142,7 +146,9 @@ async def test_execute_shell_copies_user_env_before_execution(monkeypatch):
     calls = []
 
     class FakeShell:
-        async def exec(self, command, cwd=None, background=False, env=None):
+        async def exec(
+            self, command, cwd=None, background=False, env=None, timeout=None
+        ):
             env["MUTATED_BY_FAKE_SHELL"] = command
             calls.append(env)
             return {"success": True, "stdout": "", "stderr": "", "exit_code": 0}
@@ -186,7 +192,9 @@ async def test_execute_shell_avoids_double_background_for_detached_commands(
     calls = []
 
     class FakeShell:
-        async def exec(self, command, cwd=None, background=False, env=None):
+        async def exec(
+            self, command, cwd=None, background=False, env=None, timeout=None
+        ):
             calls.append({"command": command, "background": background})
             return {"success": True, "stdout": "", "stderr": "", "exit_code": 0}
 
@@ -229,7 +237,9 @@ async def test_execute_shell_recognizes_commented_background_command(monkeypatch
     calls = []
 
     class FakeShell:
-        async def exec(self, command, cwd=None, background=False, env=None):
+        async def exec(
+            self, command, cwd=None, background=False, env=None, timeout=None
+        ):
             calls.append({"command": command, "background": background})
             return {"success": True, "stdout": "", "stderr": "", "exit_code": 0}
 
@@ -292,7 +302,9 @@ async def test_execute_shell_reports_blank_exception_type(monkeypatch):
             return ""
 
     class FakeShell:
-        async def exec(self, command, cwd=None, background=False, env=None):
+        async def exec(
+            self, command, cwd=None, background=False, env=None, timeout=None
+        ):
             raise BlankError()
 
     class FakeBooter: