Guarded screen actions: pick the command from the selected item's state #68

Screenplay 4.81 lets a screen offer one action whose command depends on the selected item (Cratis/Screenplay#432):

action "Close"
  when status == Open execute CloseTicket
  when status == Pending execute CancelTicket
  otherwise hidden

The first alternative whose condition holds decides; a condition on a missing or null field does not match; when none holds, the otherwise fallback runs (execute <Command>) or the action is hidden (otherwise hidden, also the default); with no item selected the action is hidden even when a fallback exists. Screenplay notes that running the selection needs renderer support.

Scene cannot express this today, so Stage refuses such screens (STAGE-SCENE-ACTION-001, Cratis/Stage#209):

• CoreAction in Scene 4.2.0 (Source/JavaScript/react/core/ScreenplayCoreComponents.tsx) raises one cratis.scene.command with a single command and no selected item; no guarded-action component is registered in coreComponents.ts.
• InteractionBinding in Scene.Model 4.7.0 has an optional guard for an action sequence, not ordered first-match command selection or visibility; ExecuteCommandAction carries only a command.

Needed in Scene: a core:guarded-action element (model and wire schema, React component, registry and package entry) with ordered alternatives of structured conditions plus command and input bindings, a selected-item binding from the screen or table, first-match evaluation where null or missing fields never match (also for inequality), an execute or hidden fallback with hidden as default, hiding when nothing is selected, and post-success navigation for the chosen command. Conformance specs in .NET and TypeScript.

Once it exists, Stage maps the syntax onto it and wires a command route and form for every alternative and the fallback.

Status

State: Done — Shipped in Scene v4.83.0 (PR #272, merge e0f199d).
Branch: studio-856-auto-merge (#272)
Scope: core:guarded-action (ordered first-match alternatives, selected item, hidden/execute fallback) plus first-match interaction branches; unblocks Stage#209. Planning first.
Plan: Add a core:guarded-action element using the property shape Stage already emits: an item binding, ordered alternatives (each a condition, a command and its arguments), a hidden or execute fallback, and post-success navigation. Add optional first-match alternatives/otherwise to InteractionBinding. C# and TypeScript evaluators share one fixture corpus; null and missing fields follow Screenplay 0029, and guards that cannot be evaluated fail closed. Additive minor release.
Delivered: Nothing yet.
Remaining: To be confirmed.
Follow-ups: None.