Server,Session(feat): add start_server, lock_session

why: Complete server lifecycle and session locking for programmatic use.
what:
- Add Server.start_server() wrapping start-server (idempotent)
- Add Session.lock_session() wrapping lock-session
- Add tests for both

Author: tony

src/libtmux/server.py

@@ -673,6 +673,21 @@ def list_commands(self, *, command_name: str | None = None) -> list[str]:
 
         return proc.stdout
 
+    def start_server(self) -> None:
+        """Start the tmux server if not already running.
+
+        Wraps ``$ tmux start-server``. Usually not needed since the server
+        starts automatically on first session creation.
+
+        Examples
+        --------
+        >>> server.start_server()
+        """
+        proc = self.cmd("start-server")
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
     def show_messages(self) -> list[str]:
         """Show server message log via ``$ tmux show-messages``.
 

src/libtmux/session.py

@@ -245,6 +245,18 @@ def cmd(
     Commands (tmux-like)
     """
 
+    def lock_session(self) -> None:
+        """Lock this session via ``$ tmux lock-session``.
+
+        Examples
+        --------
+        >>> session.lock_session()
+        """
+        proc = self.cmd("lock-session")
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
     def detach_client(
         self,
         *,

tests/test_server.py

@@ -461,6 +461,12 @@ def test_tmux_bin_invalid_path_raise_if_dead() -> None:
         s.raise_if_dead()
 
 
+def test_start_server(server: Server) -> None:
+    """Test Server.start_server() runs without error."""
+    server.new_session(session_name="startsvr_test")
+    server.start_server()  # idempotent — already running
+
+
 def test_bind_unbind_key(server: Server) -> None:
     """Test Server.bind_key() and unbind_key() cycle."""
     server.new_session(session_name="bind_test")

tests/test_session.py

@@ -576,6 +576,11 @@ def patched_cmd(cmd_name: str, *args: t.Any, **kwargs: t.Any) -> tmux_cmd:
         test_session.attach()
 
 
+def test_lock_session(session: Session) -> None:
+    """Test Session.lock_session() runs without error."""
+    session.lock_session()
+
+
 def test_detach_client(
     control_mode: t.Callable[..., t.Any],
     session: Session,