Allow sending an active pane to a new session or existing session without restarting the process

I have long-running processes and TUIs that I want to park in their own sessions so they do not clutter active work.

Zellij can move a pane to a new or existing tab in the same session, but I could not find a way to move a live pane into a different session, or break it out into a new session, without restarting the process.

What I want is roughly:

• send the active pane to a new session
• send the active pane to an existing session
• keep the running process alive
• leave the source pane usable if the transfer fails

Related history

Earlier cross-session request

• #2681 requested linking one live window and process into multiple sessions. The maintainer confirmed that Zellij still needs "sharing panes between sessions." The author closed the issue after receiving the answer; no implementation landed.

Implemented same-session precursors

• #196, #853, and #2664 cover the request, groundwork, and implementation for moving a live pane to a new or adjacent tab without restarting its process.
• #3610 added plugin APIs for moving live panes to a new or existing tab.
• #616 proposes reference or view panes so one live process can appear in multiple tabs.

These all stop at the session boundary. This issue tracks moving or sharing the live pane across that boundary.

Maintainer status: https://github.com/zellij-org/zellij/issues/5118#issuecomment-4359717566