Imported from belluga/delphi-ai (skills/flutter-widget-local-state-heuristics/SKILL.md). Install upstream with npx skills add belluga/delphi-ai --skill flutter-widget-local-state-heuristics. Copyright stays with the author.

Widget Local State Heuristics

Allowed (ephemeral) — setState OK

All of the following must be true:

• UI-only state, no domain/repository usage, no side effects.
• Lifetime ends with a single sheet/dialog/screen pop.
• Not referenced by routes, ModuleScope, or shared controllers.
• Purely visual toggles (expand/collapse, selection highlight, password visibility).

Not allowed (ModuleScope-adjacent) — controller required

Any of the following is true:

• Depends on repositories, domain models, auth, or router.
• Must survive rebuilds/navigation or is reused across widgets.
• Coordinates multiple widgets or drives validation/business logic.
• Lives inside presentation/**/screens/** or feature routes.

Enforcement

• If in doubt, use a controller + StreamValue.
• Do not introduce setState into ModuleScope-affiliated widgets.