What Multi-Participant Adds
Multi-participant interactions extend a normal command row into a route with participant entry, quorum, contribution, progress snapshots, route identity, and optional cancellation. Start with a working Solo command. In Command Details, switch the row from Solo to Co-op when the command should wait for other participants or accumulate group contribution; that keeps point ids, command ids, input actions, prompt text, and execution actions easy to validate first.
Route State
When a command runs as a group interaction, runtime state is represented through FInteractionRuntimeRouteIdentity, FInteractionRuntimeRouteProgressSnapshot, and FInteractionRuntimeParticipantSnapshot. UI code sees route phase and participant-role data through prompt presentation and canonical route projection. Execution actions receive an execution context that tells them whether the command has a multi-participant session and whether the local participant is the initiator.
Authoring Areas
The Command Details panel owns the route configuration when Co-op is selected: Required Participants, Enter Mode, Enter Release Behavior, Pattern, Release Behavior, Resolution Policy, Cancel Input Action, Commit Hold Duration, Pattern Tap Count, Pattern Tap Window, Contribution Rate Per Second, and Decay Rate Per Second. The point owns admission capacity, which limits how many participants a surface can admit for group routes.