ControlModeEngine(feat): Add set_client_flags() for runtime flag control

Add method to set tmux client flags at runtime via `refresh-client -f`:
- no_output: Filter %output notifications (reduce noise)
- pause_after: Pause output after N seconds (flow control)

This follows tmux's design where CLIENT_CONTROL_* flags are runtime
modifiable, not connection-time parameters.

Also fix ServerContext.to_args() to produce concatenated form
(e.g., "-Lsocket_name") matching Server._build_server_args().

Author: tony

src/libtmux/_internal/engines/base.py

@@ -26,14 +26,18 @@ class ServerContext:
     config_file: str | None = None
 
     def to_args(self) -> tuple[str, ...]:
-        """Convert context to tmux server argument tuple."""
+        """Convert context to tmux server argument tuple.
+
+        Returns args in concatenated form (e.g., ``-Lsocket_name``) to match
+        the format used by ``Server._build_server_args()``.
+        """
         args: list[str] = []
         if self.socket_name:
-            args.extend(["-L", self.socket_name])
+            args.append(f"-L{self.socket_name}")
         if self.socket_path:
-            args.extend(["-S", str(self.socket_path)])
+            args.append(f"-S{self.socket_path}")
         if self.config_file:
-            args.extend(["-f", str(self.config_file)])
+            args.append(f"-f{self.config_file}")
         return tuple(args)
 
 

src/libtmux/_internal/engines/control_mode.py

@@ -311,6 +311,53 @@ def drain_notifications(
         msg = f"Notification queue did not become idle within {timeout}s"
         raise TimeoutError(msg)
 
+    def set_client_flags(
+        self,
+        *,
+        no_output: bool | None = None,
+        pause_after: int | None = None,
+    ) -> None:
+        """Set control client flags via refresh-client.
+
+        These correspond to tmux's runtime client flags (set via
+        ``refresh-client -f``), not connection-time parameters. This follows
+        tmux's design where CLIENT_CONTROL_* flags are modified at runtime.
+
+        Parameters
+        ----------
+        no_output : bool, optional
+            Filter %output notifications (reduces noise when attached to active panes).
+            Set to True to enable, False to disable, None to leave unchanged.
+        pause_after : int, optional
+            Pause output after N seconds of buffering (flow control).
+            Set to 0 to disable, positive int to enable, None to leave unchanged.
+
+        Examples
+        --------
+        >>> engine.set_client_flags(no_output=True)  # doctest: +SKIP
+        >>> engine.set_client_flags(pause_after=5)   # doctest: +SKIP
+        >>> engine.set_client_flags(no_output=False) # doctest: +SKIP
+        """
+        flags: list[str] = []
+        if no_output is True:
+            flags.append("no-output")
+        elif no_output is False:
+            flags.append("no-output=off")
+
+        if pause_after is not None:
+            if pause_after == 0:
+                flags.append("pause-after=none")
+            else:
+                flags.append(f"pause-after={pause_after}")
+
+        if flags:
+            server_args = self._server_context.to_args() if self._server_context else ()
+            self.run(
+                "refresh-client",
+                cmd_args=("-f", ",".join(flags)),
+                server_args=server_args,
+            )
+
     def get_stats(self) -> EngineStats:
         """Return diagnostic statistics for the engine."""
         return self._protocol.get_stats(restarts=self._restarts)