Each pane has a separate holder process. The holder owns the pseudo-terminal (PTY) or pipe for the agent. It stores a limited amount of recent output.
If the server stops, the holder keeps the pane process active. A new server reconnects through the holder/1 protocol. Input IDs and acknowledgments prevent duplicate input.
Recovery limits
After a server restart, the holder replays output from its checkpoint. The server then requests a screen redraw. Screen recovery can be incomplete.
The holder preserves processes through a server crash, server restart, or client disconnect. A host restart or holder failure stops those processes.