Synchronize-panes behavior during multi-line input across diverse shell environments

The synchronize-panes window option in tmux 3.x enables simultaneous input replication across all active panes. While this is effective for simple commands, the behavior becomes unpredictable when sending complex key sequences or multi-line pastes to panes running different shell environments (e.g., Bash vs. Zsh) or different terminal emulators.

Because synchronization operates at the input level, differences in how various shells handle line wrapping, auto-completion, or bracketed paste mode can lead to desynchronized command execution or partial input delivery across the window.

• How does tmux handle input buffering when panes have differing shell configurations during a multi-line paste?
• Is there a mechanism to ensure atomic command delivery across synchronized panes to prevent partial execution?