Cinemarco

Implement F# backend using Giraffe + Fable.Remoting with proper layer separation. Use when: "implement backend", "add API", "create endpoint", "server logic", "business rules", "backend for X", "API implementation", "server-side", "Giraffe", "Fable.Remoting". Layers: Validation → Domain (pure) → Persistence (I/O) → API. Creates code in src/Server/: Validation.fs, Domain.fs, Persistence.fs, Api.fs.

Orchestrates end-to-end F# full-stack feature development across all layers. Use when: "add feature", "implement X", "build Y", "create new feature", "full stack", "new functionality", "add capability", "implement end-to-end", "complete feature". Guides through: Shared types → Backend → Frontend → Tests. Use this for features that touch multiple layers of the application.

Implement F# frontend using Elmish MVU architecture with Feliz for React components. Use when: "add UI", "create component", "build form", "frontend", "client-side", "user interface", "view", "display", "render", "Elmish", "Feliz", "button", "input", "state management". Creates Model/Msg/update in src/Client/State.fs and views in src/Client/View.fs. Follows strict MVU pattern with RemoteData for async operations and TailwindCSS/DaisyUI for styling.

Implement data persistence using SQLite with Dapper, JSON files, or event sourcing. Use when: "database", "save data", "store", "CRUD", "create table", "query", "SQL", "SQLite", "Dapper", "file storage", "JSON file", "event sourcing", "persistence", "read from database", "write to database", "data access", "repository". Creates code in src/Server/Persistence.fs with async I/O patterns.

Implement client-side routing with Feliz.Router for F# Elmish applications. Use when: "add routing", "create pages", "navigation", "URL handling", "deep linking", "add page", "route to", "browser history", "SPA routing", "multi-page", "navigate to". Creates route definitions, URL parsing, and navigation patterns in src/Client/.

Define shared domain types and API contracts for F# full-stack applications. Use when: "define types", "create entity", "add model", "API contract", "shared types", "domain model", "record", "discriminated union", "data structure", "DTO", "interface", "type definition", "new entity", "modify types". Creates types in src/Shared/Domain.fs and API interfaces in src/Shared/Api.fs. Always start here when adding new features.

Write comprehensive tests using Expecto for F# applications. Use when: "add tests", "write tests", "test X", "unit test", "testing", "verify", "Expecto", "test coverage", "TDD", "property test", "async test", "test case". Creates tests in src/Tests/ for domain logic, validation, persistence, and state. Focus on pure functions (domain) and validation rules for best coverage.

Create validation logic for F# backends with error accumulation and async validation. Use when: "add validation", "validate X", "input validation", "complex validation", "business rules", "check email", "required fields", "async validation", "database uniqueness", "cross-field validation", "validation errors". Creates validators in src/Server/Validation.fs. Use for complex scenarios; basic validation patterns are in fsharp-backend skill.

Deploy F# applications with Tailscale sidecar for private network access. Use when: "deploy", "production", "Tailscale", "docker-compose", "Docker", "Portainer", "private network", "deployment", "ship it", "go live", "home server", "self-host", "container", "release". Creates docker-compose.yml with app + Tailscale sidecar for secure access. No public ports, no authentication needed - Tailscale handles it.