session_source Fork

session_source is a member-level OpenRig field that declares how a newly-launched managed seat should derive its initial conversation continuity from a prior runtime conversation source.

v1 supports one mode: fork — start a new managed seat from a prior native runtime conversation source without claiming the original seat continued.

The schema is runtime-neutral; implementation is runtime-specific (Claude and Codex have their own native fork commands).

Use this when

• Authoring a rig spec member that should fork from a prior session
• Authoring a rig expand payload with session_source
• Reasoning about whether to use fork vs rebuild vs resume vs fresh for a new seat
• Composing fork + handover (seat-handover-over-fork) — see seat-continuity-and-handover skill