FOSMVVM Fields Generator

Generate Form Specifications following FOSMVVM patterns.

Conceptual Foundation

For full architecture context, see FOSMVVMArchitecture.md | OpenClaw reference

A Form Specification (implemented as a {Name}Fields protocol) is the single source of truth for user input. It answers:

1. What data can the user provide? (properties)
2. How should it be presented? (FormField with type, keyboard, autofill semantics)
3. What constraints apply? (validation rules)
4. What messages should be shown? (localized titles, placeholders, errors)

Why This Matters

The Form Specification is defined once, used everywhere:

// Same protocol adopted by different consumers:
struct CreateIdeaRequestBody: ServerRequestBody, IdeaFields { ... }  // HTTP transmission
@ViewModel struct IdeaFormViewModel: IdeaFields { ... }              // Form rendering
final class Idea: Model, IdeaFields { ... }                          // Persistence validation

This ensures:

• Consistent validation - Same rules on client and server
• Shared localization - One YAML file, used everywhere
• Single source of truth - Change once, applies everywhere

Connection to FOSMVVM

Form Specifications integrate with:

• Localization System - FormField titles/placeholders and validation messages use LocalizableString
• Validation System - Implements ValidatableModel protocol
• Request System - RequestBody types adopt Fields for validated transmission
• ViewModel System - ViewModels adopt Fields for form rendering

When to Use This Skill

• Defining a new form (create, edit, filter, search)
• Adding validation to a request body
• Any type that needs to conform to ValidatableModel
• When fosmvvm-fluent-datamodel-generator needs form fields for a DataModel

What This Skill Generates

A complete Form Specification consists of 3 files:

| File | Purpose |

|------|---------|

| {Name}Fields.swift | Protocol + FormField definitions + validation methods |

| {Name}FieldsMessages.swift | @FieldValidationModel struct with @LocalizedString properties |

| {Name}FieldsMessages.yml | YAML localization (titles, placeholders, error messages) |

Project Structure Configuration

Replace placeholders with your project's actual paths:

| Placeholder | Description | Example |

|-------------|-------------|---------|

| {ViewModelsTarget} | Shared ViewModels SPM target | ViewModels, SharedViewModels |

| {ResourcesPath} | Localization resources path | Sources/Resources |

Expected Structure:

Sources/
  {ViewModelsTarget}/
    FieldModels/
      {Name}Fields.swift
      {Name}FieldsMessages.swift
  {ResourcesPath}/
    FieldModels/
      {Name}FieldsMessages.yml

How to Use This Skill

Invocation:

/fosmvvm-fields-generator

Prerequisites:

• Form purpose understood from conversation context
• Field requirements discussed (names, types, constraints)
• Entity relationship identified (what is this form creating/editing)

Workflow integration:

This skill is used when defining form validation and user input contracts. The skill references conversation context automatically—no file paths or Q&A needed. Often precedes fosmvvm-fluent-datamodel-generator for form-backed models.

Pattern Implementation

This skill references conversation context to determine Fields protocol structure:

Form Analysis

From conversation context, the skill identifies:

• Form purpose (create, edit, filter, login, settings)
• Entity relation (User, Idea, Document - what's being created/edited)
• Protocol naming (CreateIdeaFields, UpdateProfile, LoginCredentials)

Field Design

For each field from requirements:

• Property specification (name, type, optional vs required)
• Presentation type (FormFieldType: text, textArea, select, checkbox)
• Input semantics (FormInputType: email, password, tel, date)
• Constraints (required, length range, value range, date range)
• Localization (title, placeholder, validation error messages)

File Generation Order

1. Fields protocol with FormField definitions and validation
2. FieldsMessages struct with @LocalizedString properties
3. FieldsMessages YAML with localized strings

Context Sources

Skill references information from:

• Prior conversation: Form requirements, field specifications discussed
• Specification files: If Claude has read form specs into context
• Existing patterns: From codebase analysis of similar Fields protocols

Key Patterns

Protocol Structure

public protocol {Name}Fields: ValidatableModel, Codable, Sendable {
    var fieldName: FieldType { get set }
    var {name}ValidationMessages: {Name}FieldsMessages { get }
}

FormField Definition

static var contentField: FormField<String?> { .init(
    fieldId: .init(id: "content"),
    title: .localized(for: {Name}FieldsMessages.self, propertyName: "content", messageKey: "title"),
    placeholder: .localized(for: {Name}FieldsMessages.self, propertyName: "content", messageKey: "placeholder"),
    type: .textArea(inputType: .text),
    options: [
        .required(value: true)
    ] + FormInputOption.rangeLength(contentRange)
) }

FormField Types Reference

| FormFieldType | Use Case |

|---------------|----------|

| .text(inputType:) | Single-line input |

| .textArea(inputType:) | Multi-line input |

| .checkbox | Boolean toggle |

| .select | Dropdown selection |

| .colorPicker | Color selection |

FormInputType Reference (common ones)

| FormInputType | Keyboard/Autofill |

|---------------|-------------------|

| .text | Default keyboard |

| .emailAddress | Email keyboard, email autofill |

| .password | Secure entry |

| .tel | Phone keyboard |

| .url | URL keyboard |

| .date, .datetimeLocal | Date picker |

| .givenName, .familyName | Name autofill |

Validation Method Pattern

internal func validateContent(_ fields: [FormFieldBase]?) -> [ValidationResult]? {
    guard fields == nil || (fields?.contains(Self.contentField) == true) else {
        return nil
    }

    var result = [ValidationResult]()

    if content.isEmpty {
        result.append(.init(
            status: .error,
            field: Self.contentField,
            message: {name}ValidationMessages.contentRequiredMessage
        ))
    } else if !Self.contentRange.contains(NSString(string: content).length) {
        result.append(.init(
            status: .error,
            field: Self.contentField,
            message: {name}ValidationMessages.contentOutOfRangeMessage
        ))
    }

    return result.isEmpty ? nil : result
}

Messages Struct Pattern

@FieldValidationModel public struct {Name}FieldsMessages {
    @LocalizedString("content", messageGroup: "validationMessages", messageKey: "required")
    public var contentRequiredMessage

    @LocalizedString("content", messageGroup: "validationMessages", messageKey: "outOfRange")
    public var contentOutOfRangeMessage
}

YAML Structure

en:
  {Name}FieldsMessages:
    content:
      title: "Content"
      placeholder: "Enter your content..."
      validationMessages:
        required: "Content is required"
        outOfRange: "Content must be between 1 and 10,000 characters"

Naming Conventions

| Concept | Convention | Example |

|---------|------------|---------|

| Protocol | {Name}Fields | IdeaFields, CreateIdeaFields |

| Messages struct | {Name}FieldsMessages | IdeaFieldsMessages |

| Messages property | {name}ValidationMessages | ideaValidationMessages |

| Field definition | {fieldName}Field | contentField |

| Range constant | {fieldName}Range | contentRange |

| Validate method | validate{FieldName} | validateContent |

| Required message | {fieldName}RequiredMessage | contentRequiredMessage |

| OutOfRange message | {fieldName}OutOfRangeMessage | contentOutOfRangeMessage |

See Also

• FOSMVVMArchitecture.md - Full FOSMVVM architecture reference
• fosmvvm-viewmodel-generator - For ViewModels that adopt Fields
• fosmvvm-fluent-datamodel-generator - For Fluent DataModels that implement Fields
• reference.md - Complete file templates

Version History

| Version | Date | Changes |

|---------|------|---------|

| 1.0 | 2024-12-24 | Initial skill |

| 2.0 | 2024-12-26 | Rewritten with conceptual foundation; generalized from Kairos-specific |

| 2.1 | 2026-01-24 | Update to context-aware approach (remove file-parsing/Q&A). Skill references conversation context instead of asking questions or accepting file paths. |