Fix use of single instance with detach

kittens/panel/main.py

@@ -349,9 +349,14 @@ def handle_single_instance_command(boss: BossType, sys_args: Sequence[str], envi
 def main(sys_args: list[str]) -> None:
     global args
     args, items = parse_panel_args(sys_args[1:])
+    talk_fd = -1
+    if args.single_instance:
+        si_data = os.environ.get('KITTY_SI_DATA', '')
+        if si_data:
+            talk_fd = int(si_data)
     if args.detach:
         from kitty.utils import detach
-        detach(log_file=args.detached_log or os.devnull)
+        detach(talk_fd, log_file=args.detached_log or os.devnull)
     sys.argv = ['kitty']
     if args.debug_rendering:
         sys.argv.append('--debug-rendering')

kitty/main.py

@@ -504,20 +504,21 @@ def _main() -> None:
         cli_opts.args = []
     else:
         cli_opts.args = rest
-    if cli_opts.detach:
-        if cli_opts.session == '-':
-            from .session import PreReadSession
-            cli_opts.session = PreReadSession(sys.stdin.read(), os.environ)
-        detach()
-    if cli_opts.replay_commands:
-        from kitty.client import main as client_main
-        client_main(cli_opts.replay_commands)
-        return
     talk_fd = -1
     if cli_opts.single_instance:
         si_data = os.environ.pop('KITTY_SI_DATA', '')
         if si_data:
             talk_fd = int(si_data)
+
+    if cli_opts.detach:
+        if cli_opts.session == '-':
+            from .session import PreReadSession
+            cli_opts.session = PreReadSession(sys.stdin.read(), os.environ)
+        detach(talk_fd)
+    if cli_opts.replay_commands:
+        from kitty.client import main as client_main
+        client_main(cli_opts.replay_commands)
+        return
     bad_lines: list[BadLine] = []
     opts = create_opts(cli_opts, accumulate_bad_lines=bad_lines)
     setup_environment(opts, cli_opts)

kitty/utils.py

@@ -257,11 +257,18 @@ def open_url(url: str, program: str | list[str] = 'default', cwd: str | None = N
     return open_cmd(command_for_open(program), url, cwd=cwd, extra_env=extra_env)
 
 
-def detach(fork: bool = True, setsid: bool = True, redirect: bool = True, log_file: str = os.devnull) -> None:
+def detach(*preserve_fds: int, fork: bool = True, setsid: bool = True, redirect: bool = True, log_file: str = os.devnull) -> None:
+    reset = []
+    for fd in preserve_fds:
+        if fd > -1 and not os.get_inheritable(fd):
+            os.set_inheritable(fd, True)
+            reset.append(fd)
     if fork:
         # Detach from the controlling process.
         if os.fork() != 0:
             raise SystemExit(0)
+    for fd in reset:
+        os.set_inheritable(fd, False)
     if setsid:
         os.setsid()
     if redirect: