Pane(feat[break_pane]): add break_pane() wrapping tmux break-pane

why: break-pane is essential for layout management, allowing a pane to be
moved into its own window programmatically.
what:
- Add break_pane() method with detach (-d) and window_name (-n) parameters
- Use -P -F#{window_id} to capture new window ID from output
- Return Window object via Window.from_window_id()
- Use server.cmd with explicit -s flag to avoid auto-target conflicts
- Add tests for basic break and named window

Author: tony

src/libtmux/pane.py

@@ -1139,6 +1139,55 @@ def enter(self) -> Pane:
         self.cmd("send-keys", "Enter")
         return self
 
+    def break_pane(
+        self,
+        *,
+        detach: bool = True,
+        window_name: str | None = None,
+    ) -> Window:
+        """Break this pane out into a new window via ``$ tmux break-pane``.
+
+        Parameters
+        ----------
+        detach : bool, optional
+            Do not switch to the new window (``-d`` flag), default True.
+        window_name : str, optional
+            Name for the new window (``-n`` flag).
+
+        Returns
+        -------
+        :class:`Window`
+            The newly created window containing the pane.
+
+        Examples
+        --------
+        >>> pane_to_break = window.split(shell='sleep 1m')
+        >>> new_window = pane_to_break.break_pane(window_name='broken')
+        >>> new_window.window_name
+        'broken'
+        """
+        tmux_args: tuple[str, ...] = ("-P", "-F#{window_id}")
+
+        if detach:
+            tmux_args += ("-d",)
+
+        if window_name is not None:
+            tmux_args += ("-n", window_name)
+
+        tmux_args += ("-s", str(self.pane_id))
+
+        # Use server.cmd to avoid auto-adding -t from self.cmd
+        proc = self.server.cmd("break-pane", *tmux_args)
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
+        window_id = proc.stdout[0].strip()
+
+        from libtmux.window import Window
+
+        return Window.from_window_id(server=self.server, window_id=window_id)
+
     def swap(
         self,
         target: str | Pane,

tests/test_pane.py

@@ -740,6 +740,36 @@ def test_split_percentage_size_mutual_exclusion(session: Session) -> None:
         pane.split(size=10, percentage=50)
 
 
+def test_break_pane_basic(session: Session) -> None:
+    """Test Pane.break_pane() creates a new window."""
+    window = session.new_window(window_name="test_break")
+    initial_window_count = len(session.windows)
+    pane = window.active_pane
+    assert pane is not None
+
+    new_pane = pane.split(shell="sleep 1m")
+    assert len(window.panes) == 2
+
+    new_window = new_pane.break_pane()
+    session.refresh()
+
+    assert len(session.windows) == initial_window_count + 1
+    window.refresh()
+    assert len(window.panes) == 1
+    assert new_window.window_id is not None
+
+
+def test_break_pane_with_name(session: Session) -> None:
+    """Test Pane.break_pane() with window_name."""
+    window = session.new_window(window_name="test_break_name")
+    pane = window.active_pane
+    assert pane is not None
+
+    new_pane = pane.split(shell="sleep 1m")
+    new_window = new_pane.break_pane(window_name="my_broken")
+    assert new_window.window_name == "my_broken"
+
+
 def test_swap_pane(session: Session) -> None:
     """Test Pane.swap() swaps two panes."""
     window = session.new_window(window_name="test_swap_pane")