diff --git a/kitty/child.py b/kitty/child.py
index 1e10b1f8b..606f26e0e 100644
--- a/kitty/child.py
+++ b/kitty/child.py
@@ -230,7 +230,7 @@ class Child:
         pass_fds: tuple[int, ...] = (),
         remote_control_fd: int = -1,
         hold_after_ssh: bool = False,
-        startup_command_via_shell_integration: Sequence[str] = (),
+        startup_command_via_shell_integration: Sequence[str] | str = (),
     ):
         self.is_clone_launch = is_clone_launch
         self.id = next(child_counter)
@@ -298,12 +298,15 @@ class Child:
             env.pop('KITTY_IS_CLONE_LAUNCH', None)
         must_run_startup_command_via_kitten = False
         if self.startup_command_via_shell_integration:
-            from .shell_integration import join
-            scmd = self.argv or resolved_shell(fast_data_types.get_options())
-            try:
-                env['KITTY_SI_RUN_COMMAND_AT_STARTUP'] = join(scmd[0], self.startup_command_via_shell_integration)
-            except Exception:
-                must_run_startup_command_via_kitten = True  # unknown shell
+            if isinstance(self.startup_command_via_shell_integration, str):
+                env['KITTY_SI_RUN_COMMAND_AT_STARTUP'] = self.startup_command_via_shell_integration
+            else:
+                from .shell_integration import join
+                scmd = self.argv or resolved_shell(fast_data_types.get_options())
+                try:
+                    env['KITTY_SI_RUN_COMMAND_AT_STARTUP'] = join(scmd[0], self.startup_command_via_shell_integration)
+                except Exception:
+                    must_run_startup_command_via_kitten = True  # unknown shell
         return env, must_run_startup_command_via_kitten
 
     def fork(self) -> int | None:
diff --git a/kitty/launch.py b/kitty/launch.py
index ac75bdf65..0cc98a7e4 100644
--- a/kitty/launch.py
+++ b/kitty/launch.py
@@ -621,7 +621,7 @@ def _launch(
     rc_from_window: Window | None = None,
     base_env: dict[str, str] | None = None,
     child_death_callback: Callable[[int, Exception | None], None] | None = None,
-    startup_command_via_shell_integration: Sequence[str] = (),
+    startup_command_via_shell_integration: Sequence[str] | str = (),
 ) -> Window | None:
     source_window = boss.active_window_for_cwd
     if opts.source_window:
@@ -837,7 +837,7 @@ def launch(
     rc_from_window: Window | None = None,
     base_env: dict[str, str] | None = None,
     child_death_callback: Callable[[int, Exception | None], None] | None = None,
-    startup_command_via_shell_integration: Sequence[str] = (),
+    startup_command_via_shell_integration: Sequence[str] | str = (),
 ) -> Window | None:
     active = boss.active_window
     if opts.keep_focus and active:
diff --git a/kitty/session.py b/kitty/session.py
index 79120f9b6..0fa5855a0 100644
--- a/kitty/session.py
+++ b/kitty/session.py
@@ -41,7 +41,10 @@ ResizeSpec = tuple[str, int]
 
 class WindowSpec:
 
-    def __init__(self, launch_spec: Union['LaunchSpec', 'SpecialWindowInstance'], serialized_id: int = 0, run_command_at_shell_startup: Sequence[str] = ()):
+    def __init__(
+        self, launch_spec: Union['LaunchSpec', 'SpecialWindowInstance'], serialized_id: int = 0,
+        run_command_at_shell_startup: Sequence[str] | str = ()
+):
         self.launch_spec = launch_spec
         self.resize_spec: ResizeSpec | None = None
         self.focus_matching_window_spec: str = ''
diff --git a/kitty/tabs.py b/kitty/tabs.py
index 584d3c000..0fad3205f 100644
--- a/kitty/tabs.py
+++ b/kitty/tabs.py
@@ -537,7 +537,7 @@ class Tab:  # {{{
         pass_fds: tuple[int, ...] = (),
         remote_control_fd: int = -1,
         hold_after_ssh: bool = False,
-        startup_command_via_shell_integration: Sequence[str] = (),
+        startup_command_via_shell_integration: Sequence[str] | str = (),
     ) -> Child:
         check_for_suitability = True
         if cmd is None:
@@ -629,7 +629,7 @@ class Tab:  # {{{
         remote_control_fd: int = -1,
         next_to: Window | None = None,
         hold_after_ssh: bool = False,
-        startup_command_via_shell_integration: Sequence[str] = (),
+        startup_command_via_shell_integration: Sequence[str] | str = (),
     ) -> Window:
         cs = WindowCreationSpec(
             use_shell=use_shell, cmd=cmd, has_stdin=bool(stdin), override_title=override_title, cwd_from=cwd_from,
diff --git a/kitty/window.py b/kitty/window.py
index d382f84a1..93470627f 100644
--- a/kitty/window.py
+++ b/kitty/window.py
@@ -2009,17 +2009,20 @@ class Window:
         if self.creation_spec and self.creation_spec.cmd:
             if self.creation_spec.cmd != resolved_shell(get_options()):
                 cmd = self.creation_spec.cmd
-        unserialize_data: dict[str, int | list[str]] = {'id': self.id}
-        if not cmd and ser_opts.use_foreground_process and self.child.pid != (pid := self.child.pid_for_cwd) and pid is not None:
-            # we have a shell running some command
-            with suppress(Exception):
-                fcmd = self.child.cmdline_of_pid(pid)
-                if fcmd:
-                    unserialize_data['cmd_at_shell_startup'] = fcmd
-                    if not os.path.isabs(fcmd[0]):
-                        with suppress(Exception):
-                            from .child import abspath_of_exe
-                            fcmd[0] = abspath_of_exe(pid)
+        unserialize_data: dict[str, int | list[str] | str] = {'id': self.id}
+        if not cmd and ser_opts.use_foreground_process:
+            if not self.at_prompt and self.last_cmd_cmdline:
+                unserialize_data['cmd_at_shell_startup'] = self.last_cmd_cmdline
+            elif self.child.pid != (pid := self.child.pid_for_cwd) and pid is not None:
+                # we have a shell running some command
+                with suppress(Exception):
+                    fcmd = self.child.cmdline_of_pid(pid)
+                    if fcmd:
+                        unserialize_data['cmd_at_shell_startup'] = fcmd
+                        if not os.path.isabs(fcmd[0]):
+                            with suppress(Exception):
+                                from .child import abspath_of_exe
+                                fcmd[0] = abspath_of_exe(pid)
         ans.insert(1, unserialize_launch_flag + json.dumps(unserialize_data))
         ans.extend(cmd)
         return ans