formidable-expert

name	formidable-expert
description	Develop and review the Formidable Swift form-management framework and its SwiftUI integration. Use when working on Formidable, FormField, FormFieldRepresentable, Emptable, Mensurable, validation or KeyPath rules, Binding-backed and transformed fields, reset/validate state transitions, `.field` error presentation and accessibility, API compatibility, tests, or public documentation.

Formidable Expert

Use the repository's AGENTS.md as the project-specific source of truth. Inspect the current implementation before changing behavior; report any discrepancy before altering a public contract.

Workflow

1. Read AGENTS.md, the affected source, and its focused tests.
2. Load only the references needed for the task:
   • references/forms.md: form discovery, contracts, aggregate state, validation, and reset.
   • references/field-lifecycle.md: local and external storage, transformations, modification state, and error visibility.
   • references/rules.md: built-in and custom static/KeyPath rule patterns.
   • references/swiftui.md: .field, accessibility, visibility, disabled state, and error presentation.
3. Preserve Swift 6.2 compatibility across iOS 17+, macOS 15+, and tvOS 17+.
4. Apply $swift-mark-organization to modified Swift files. Apply $swiftui-expert-skill to SwiftUI, Observation, animation, accessibility, or state-ownership work. Use the view-refactor or performance-audit skills only under the conditions in AGENTS.md.
5. Add focused Swift Testing coverage for every changed rule, contract, field, or form state transition.
6. Run swift test from the package root. Treat any documented test count as informational.

Invariants

• Keep Formidable free of an actor-isolation requirement; isolate concrete app types only when their usage requires it.
• Preserve FormFieldRepresentable: ObservableObject compatibility while using @Observable for new observable reference types.
• Store rules directly as [any FormFieldRule]. Keep AnyRule internal and absent from call sites.
• Preserve field/rule order when collecting errors and throwing the first validation failure.
• Exclude hidden and disabled fields from validation.
• Keep public APIs documented with ///; give public components a compiling # Example.
• Preserve source compatibility unless the requested change explicitly migrates a public contract.