uefn-ui-widgets

Sources: Claude/docs/mcp/ui-widgets.md, entry B1 of SKILLS-PROPOSAL.md, recipes.json. Cross-cutting skills to always follow: uefn-mcp-lab-guard (lab guard) e uefn-create-use-remove-one-script (create, use, remove in ONE script).

Rules

• Paths always in GUID form: {lab} = /<guid>/<project> (e.g. /09e4e8d3-.../root_ai_lab). /root_ai_lab/... is refused by the editor.
• {bp} = {lab}/UI_X/WBP_X.WBP_X; widget parts: {bp}:WidgetTree.<Name>.
• The guard is not bypassed: a refusal is reported as is. If a recipe fails: report the exact error and STOP (no creative retries).
• Call: call_tool {toolset_name, tool_name, arguments}. After every change: CompileWidgetBlueprint and read the result (save_assets returning true is NOT enough).
• Cleanup: AssetTools/delete {path: <bp without .Name>}.

Verified recipes

Toolset: UMGToolSet.UMGToolSet, VerseFieldsToolset.VerseFieldsToolset, MVVMToolset.MVVMToolset, WidgetAnimationToolset.WidgetAnimationToolset.

1. UMGToolSet/CreateWidgetBlueprint {"folderPath":"{lab}/UI_X","assetName":"WBP_X","parentClass":{"refPath":"/Script/UMG.UserWidget"}}
2. UMGToolSet/AddWidget {"widgetBlueprint":{"refPath":"{bp}"},"widgetClass":{"refPath":"/Script/UMG.Overlay"},"widgetDisplayName":"Root","parentWidget":null}; children: parentWidget {"refPath":"{bp}:WidgetTree.Root"} (the parent must be a panel).
3. Text: UMGToolSet/ReplaceWidgetWithTemplate {"widgetBlueprint":{"refPath":"{bp}"},"widgetToReplace":{"refPath":"{bp}:WidgetTree.<Name>"},"templateClass":{"refPath":"/Game/Valkyrie/UMG/UEFN_TextBlock.UEFN_TextBlock_C"}} (the only way to get text; the widget to replace is e.g. an Image).
4. UMGToolSet/GetWidgets {"widgetBlueprint":{"refPath":"{bp}"}}; CompileWidgetBlueprint {"widgetBlueprint":{"refPath":"{bp}"}}
5. VerseFieldsToolset/AddVerseField {"widgetBlueprint":..,"fieldName":"Op","spec":{"type":"float","defaultValue":"0.5"}} (writeAccess only "" or <public>); cleanup RemoveVerseField.
6. VerseFieldsToolset/BindWidgetPropertyToVerseField {"widgetBlueprint":..,"verseFieldName":"Op","targetWidget":{"refPath":"{bp}:WidgetTree.<Name>"},"widgetPropertyPath":"RenderOpacity"} -> GUID binding.
7. MVVMToolset/CreateViewBinding {"widgetBlueprint":..,"sourceContext":null,"sourcePropertyPath":"<campo>","destinationContext":{"refPath":"{bp}:WidgetTree.<Name>"},"destinationPropertyPath":"Text","conversionName":""}; SetBindingMode {..,"bindingId":"<guid>","mode":"TwoWay"}; ListWidgetViewBindings {"widgetBlueprint":..}; cleanup RemoveWidgetViewBinding {widgetBlueprint, bindingId}.
8. MVVMToolset/AddViewModelToWidget {"widgetBlueprint":..,"viewModelClass":{"refPath":"/Script/SimpleVotingOptionRuntime.VotingOptionViewModel"}} (returns null; no cleanup: delete the blueprint).
9. WidgetAnimationToolset/CreateWidgetAnimation {"widgetBlueprint":..,"animationName":"FadeIn","lengthSeconds":2.0}; AddWidgetToAnimation {..,"animation":{"refPath":"{bp}:FadeIn"},"objectToBind":{"refPath":"{bp}:WidgetTree.<Name>"}}; ListWidgetAnimations {"widgetBlueprint":..}; cleanup RemoveWidgetBinding {animation, bindingGuid}, RemoveWidgetAnimation.

To try (not verified)

• UMGToolSet/AddUIComponent (+ MoveUIComponent, RemoveUIComponent): guard-refused/rejected by the project (4 classes not allowed, 3 attempts). Do not retry.
• MVVMToolset/AddViewModelProperty: rejected, needs a ViewModel Blueprint that no tool creates.
• MVVMToolset/CreateViewEventBinding: unverified in recipes.json; accepts a wrong destination and the compile then fails while save_assets stays true; no tool removes the event binding.
• ObjectTools/set_properties / get_properties on the text (values = JSON string, camelCase): described in ui-widgets.md R2, non verified in recipes.json for this toolset.
• MoveWidget, RenameWidgetAnimation (resets displayLabel): unverified in recipes.json. Animation playback: unverified (needs a play session).

Binding limits (reported by community tools; confirm with the compile result)

• A binding needs the same type on both sides: no implicit conversion for int to float, logic to Visibility, texture or material to Brush (those need a conversion function or node; do them in the editor UI, then bind field to field).
• Works as is: message/string to Text, color to ColorAndOpacity, float to RenderOpacity, logic to IsEnabled, and a parent field to a child widget's field of the same type.
• The UEFN buttons expose only Text as a bindable property. Category order of Verse fields cannot be changed.

Don't

Do not use AddWidget with TextBlock/UEFN_TextBlock_C (not allowed); do not declare it "done" if only save_assets is true; do not touch assets outside the lab folder.