Server(feat[buffers]): add set_buffer, show_buffer, delete_buffer wrapping tmux buffer commands

why: Paste buffer management is needed for programmatic clipboard-like
operations between panes and for exporting/importing text data.
what:
- Add Server.set_buffer() wrapping set-buffer with append (-a) and
  buffer_name (-b) parameters
- Add Server.show_buffer() wrapping show-buffer with buffer_name (-b)
- Add Server.delete_buffer() wrapping delete-buffer with buffer_name (-b)
- Add BufferCase NamedTuple parametrized tests for set/show cycle,
  named buffers, append, and delete

Author: tony

src/libtmux/server.py

@@ -528,6 +528,100 @@ def wait_for(
         if proc.stderr:
             raise exc.LibTmuxException(proc.stderr)
 
+    def set_buffer(
+        self,
+        data: str,
+        *,
+        buffer_name: str | None = None,
+        append: bool | None = None,
+    ) -> None:
+        """Set a paste buffer via ``$ tmux set-buffer``.
+
+        Parameters
+        ----------
+        data : str
+            Data to store in the buffer.
+        buffer_name : str, optional
+            Name of the buffer (``-b`` flag).
+        append : bool, optional
+            Append to the buffer instead of replacing (``-a`` flag).
+
+        Examples
+        --------
+        >>> server.set_buffer('hello')
+        >>> server.show_buffer()
+        'hello'
+        """
+        tmux_args: tuple[str, ...] = ()
+
+        if append:
+            tmux_args += ("-a",)
+
+        if buffer_name is not None:
+            tmux_args += ("-b", buffer_name)
+
+        tmux_args += (data,)
+
+        proc = self.cmd("set-buffer", *tmux_args)
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
+    def show_buffer(self, *, buffer_name: str | None = None) -> str:
+        """Show content of a paste buffer via ``$ tmux show-buffer``.
+
+        Parameters
+        ----------
+        buffer_name : str, optional
+            Name of the buffer (``-b`` flag). Defaults to the most recent.
+
+        Returns
+        -------
+        str
+            Buffer content.
+
+        Examples
+        --------
+        >>> server.set_buffer('test_data')
+        >>> server.show_buffer()
+        'test_data'
+        """
+        tmux_args: tuple[str, ...] = ()
+
+        if buffer_name is not None:
+            tmux_args += ("-b", buffer_name)
+
+        proc = self.cmd("show-buffer", *tmux_args)
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
+        return "\n".join(proc.stdout)
+
+    def delete_buffer(self, *, buffer_name: str | None = None) -> None:
+        """Delete a paste buffer via ``$ tmux delete-buffer``.
+
+        Parameters
+        ----------
+        buffer_name : str, optional
+            Name of the buffer to delete (``-b`` flag). Defaults to the most
+            recent.
+
+        Examples
+        --------
+        >>> server.set_buffer('to_delete', buffer_name='del_buf')
+        >>> server.delete_buffer(buffer_name='del_buf')
+        """
+        tmux_args: tuple[str, ...] = ()
+
+        if buffer_name is not None:
+            tmux_args += ("-b", buffer_name)
+
+        proc = self.cmd("delete-buffer", *tmux_args)
+
+        if proc.stderr:
+            raise exc.LibTmuxException(proc.stderr)
+
     def switch_client(self, target_session: str) -> None:
         """Switch tmux client.
 

tests/test_server.py

@@ -12,6 +12,7 @@
 
 import pytest
 
+from libtmux import exc
 from libtmux.server import Server
 
 if t.TYPE_CHECKING:
@@ -482,6 +483,84 @@ def test_run_shell_background(server: Server) -> None:
     assert result is None
 
 
+class BufferCase(t.NamedTuple):
+    """Test case for buffer operations."""
+
+    test_id: str
+    data: str
+    buffer_name: str | None
+    append: bool | None
+    expected_content: str
+
+
+BUFFER_CASES: list[BufferCase] = [
+    BufferCase(
+        test_id="set_show_default",
+        data="hello_buf",
+        buffer_name=None,
+        append=None,
+        expected_content="hello_buf",
+    ),
+    BufferCase(
+        test_id="set_show_named",
+        data="named_data",
+        buffer_name="mybuf",
+        append=None,
+        expected_content="named_data",
+    ),
+]
+
+
+@pytest.mark.parametrize(
+    list(BufferCase._fields),
+    BUFFER_CASES,
+    ids=[c.test_id for c in BUFFER_CASES],
+)
+def test_buffer_set_show(
+    test_id: str,
+    data: str,
+    buffer_name: str | None,
+    append: bool | None,
+    expected_content: str,
+    server: Server,
+) -> None:
+    """Test Server.set_buffer() and show_buffer() cycle."""
+    server.new_session(session_name=f"buf_{test_id}")
+    kwargs: dict[str, t.Any] = {}
+    if buffer_name is not None:
+        kwargs["buffer_name"] = buffer_name
+    if append is not None:
+        kwargs["append"] = append
+
+    server.set_buffer(data, **kwargs)
+    result = server.show_buffer(buffer_name=buffer_name)
+    assert result == expected_content
+
+
+def test_buffer_append(server: Server) -> None:
+    """Test Server.set_buffer() with append flag."""
+    server.new_session(session_name="buf_append")
+    server.set_buffer("first", buffer_name="append_test")
+    server.set_buffer("_second", buffer_name="append_test", append=True)
+    result = server.show_buffer(buffer_name="append_test")
+    assert result == "first_second"
+
+
+def test_buffer_delete(server: Server) -> None:
+    """Test Server.delete_buffer()."""
+    server.new_session(session_name="buf_delete")
+    server.set_buffer("to_delete", buffer_name="del_buf")
+    # Verify it exists
+    assert server.show_buffer(buffer_name="del_buf") == "to_delete"
+
+    # Delete it
+    server.delete_buffer(buffer_name="del_buf")
+
+    # Verify it's gone — show-buffer should raise
+    with pytest.raises(exc.LibTmuxException):
+        server.show_buffer(buffer_name="del_buf")
+
+
 def test_new_session_config_file(
     server: Server,
     tmp_path: pathlib.Path,