Server,Pane(feat): add show_messages, prompt_history, send_prefix commands

why: These are the remaining simple commands that work headlessly and
are useful for programmatic inspection and control.
what:
- Add Server.show_messages() wrapping show-messages
- Add Server.show_prompt_history() wrapping show-prompt-history with
  prompt_type (-T) parameter
- Add Server.clear_prompt_history() wrapping clear-prompt-history with
  prompt_type (-T) parameter
- Add Pane.send_prefix() wrapping send-prefix with secondary (-2) flag
- Add tests for all new methods

Author: tony

src/libtmux/pane.py

@@ -1355,6 +1355,28 @@ def pipe(
         if proc.stderr:
             raise exc.LibTmuxException(proc.stderr)
 
+    def send_prefix(self, *, secondary: bool | None = None) -> None:
+        """Send the prefix key to the pane via ``$ tmux send-prefix``.
+
+        Parameters
+        ----------
+        secondary : bool, optional
+            Send the secondary prefix key (``-2`` flag).
+
+        Examples
+        --------
+        >>> pane.send_prefix()
+        """
+        tmux_args: tuple[str, ...] = ()
+
+        if secondary:
+            tmux_args += ("-2",)
+
+        proc = self.cmd("send-prefix", *tmux_args)
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
     def respawn(
         self,
         *,

src/libtmux/server.py

@@ -528,6 +528,90 @@ def wait_for(
         if proc.stderr:
             raise exc.LibTmuxException(proc.stderr)
 
+    def show_messages(self) -> list[str]:
+        """Show server message log via ``$ tmux show-messages``.
+
+        Returns
+        -------
+        list[str]
+            Server message log lines.
+
+        Examples
+        --------
+        >>> result = server.show_messages()
+        >>> isinstance(result, list)
+        True
+        """
+        proc = self.cmd("show-messages")
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
+        return proc.stdout
+
+    def show_prompt_history(
+        self,
+        *,
+        prompt_type: str | None = None,
+    ) -> list[str]:
+        """Show prompt history via ``$ tmux show-prompt-history``.
+
+        Parameters
+        ----------
+        prompt_type : str, optional
+            Prompt type to show (``-T`` flag). One of: ``command``,
+            ``search``, ``target``, ``window-target``.
+
+        Returns
+        -------
+        list[str]
+            Prompt history lines.
+
+        Examples
+        --------
+        >>> result = server.show_prompt_history()
+        >>> isinstance(result, list)
+        True
+        """
+        tmux_args: tuple[str, ...] = ()
+
+        if prompt_type is not None:
+            tmux_args += ("-T", prompt_type)
+
+        proc = self.cmd("show-prompt-history", *tmux_args)
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
+        return proc.stdout
+
+    def clear_prompt_history(
+        self,
+        *,
+        prompt_type: str | None = None,
+    ) -> None:
+        """Clear prompt history via ``$ tmux clear-prompt-history``.
+
+        Parameters
+        ----------
+        prompt_type : str, optional
+            Prompt type to clear (``-T`` flag). One of: ``command``,
+            ``search``, ``target``, ``window-target``.
+
+        Examples
+        --------
+        >>> server.clear_prompt_history()
+        """
+        tmux_args: tuple[str, ...] = ()
+
+        if prompt_type is not None:
+            tmux_args += ("-T", prompt_type)
+
+        proc = self.cmd("clear-prompt-history", *tmux_args)
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
     def set_buffer(
         self,
         data: str,

tests/test_pane.py

@@ -740,6 +740,13 @@ def test_split_percentage_size_mutual_exclusion(session: Session) -> None:
         pane.split(size=10, percentage=50)
 
 
+def test_send_prefix(session: Session) -> None:
+    """Test Pane.send_prefix() sends prefix key without error."""
+    pane = session.active_window.active_pane
+    assert pane is not None
+    pane.send_prefix()
+
+
 def test_display_popup_runs_command(
     control_mode: t.Callable[..., t.Any],
     session: Session,

tests/test_server.py

@@ -461,6 +461,29 @@ def test_tmux_bin_invalid_path_raise_if_dead() -> None:
         s.raise_if_dead()
 
 
+def test_show_messages(server: Server) -> None:
+    """Test Server.show_messages() returns message log."""
+    server.new_session(session_name="showmsg_test")
+    result = server.show_messages()
+    assert isinstance(result, list)
+    assert len(result) > 0  # at least the new-session command log
+
+
+def test_show_prompt_history(server: Server) -> None:
+    """Test Server.show_prompt_history() returns history."""
+    server.new_session(session_name="showph_test")
+    result = server.show_prompt_history()
+    assert isinstance(result, list)
+
+
+def test_clear_prompt_history(server: Server) -> None:
+    """Test Server.clear_prompt_history() clears history."""
+    server.new_session(session_name="clearph_test")
+    server.clear_prompt_history()
+    # Verify specific type can be cleared
+    server.clear_prompt_history(prompt_type="command")
+
+
 def test_wait_for_set_flag(server: Server) -> None:
     """Test Server.wait_for() with set_flag."""
     server.new_session(session_name="wait_test")