Agent-Skills.md

Agent Skills: SOLID Swift - Apple Best Practices 2026

SOLID principles for Swift 6 and SwiftUI (iOS 26+). Files < 100 lines, protocols separated, @Observable, actors, Preview-driven development. Features Modular MANDATORY.

UncategorizedID: fusengine/agents/solid-swift

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fusengine/agents
fusengineLicense: MIT
7

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plugins/swift-apple-expert/skills/solid-swift/SKILL.md

Skill Metadata

Name
solid-swift
Description
SOLID principles for Swift 6 and SwiftUI (iOS 26+). Files < 100 lines, protocols separated, @Observable, actors, Preview-driven development. Features Modular MANDATORY.

SOLID Swift - Apple Best Practices 2026

Agent Workflow (MANDATORY)

Before ANY implementation, use TeamCreate to spawn 3 agents:

  1. fuse-ai-pilot:explore-codebase - Analyze existing architecture
  2. fuse-ai-pilot:research-expert - Verify Swift/Apple docs via Apple Docs MCP + Context7
  3. XcodeBuildMCP - Build validation after code changes. Then run fuse-ai-pilot:sniper.

DRY - Reuse Before Creating (MANDATORY)

Before writing ANY new code:

  1. Grep the codebase for similar protocols, services, or logic
  2. Check shared locations: Core/Extensions/, Core/Utilities/, Core/Protocols/
  3. If similar code exists -> extend/reuse instead of duplicate
  4. If code will be used by 2+ features -> create it in Core/ directly

Architecture (Features Modular MANDATORY)

| Layer | Location | Max Lines | |-------|----------|-----------| | Views | Features/[Feature]/Views/ | 80 | | ViewModels | Features/[Feature]/ViewModels/ | 100 | | Services | Features/[Feature]/Services/ | 100 | | Protocols | Features/[Feature]/Protocols/ | 30 | | Shared | Core/{Models,Protocols,Services,Extensions,Utilities}/ | - |

NEVER use flat Sources/ structure - always Features/[Feature]/

Critical Rules (MANDATORY)

| Rule | Value | |------|-------| | File limit | 100 lines (split at 90) | | ViewModels | @MainActor @Observable | | Protocols | Features/[Feature]/Protocols/ or Core/Protocols/ ONLY | | Models | Sendable structs | | Documentation | /// on all public APIs | | Previews | Every View MUST have #Preview |

Reference Guide

Concepts

| Topic | Reference | When to consult | |-------|-----------|-----------------| | SOLID Overview | solid-principles.md | Quick reference all principles | | SRP | single-responsibility.md | Fat views/VMs, splitting files | | OCP | open-closed.md | Adding providers, extensibility | | LSP | liskov-substitution.md | Protocol contracts, testing | | ISP | interface-segregation.md | Fat protocols, splitting | | DIP | dependency-inversion.md | Injection, testing, mocking | | Concurrency | concurrency-patterns.md | Actors, @MainActor, Sendable | | Anti-Patterns | anti-patterns.md | Code smells detection |

Templates

| Template | When to use | |----------|-------------| | view.md | SwiftUI View with subviews and #Preview | | viewmodel.md | @Observable ViewModel with @MainActor | | service.md | API Service, Mock, Cache actor | | protocol.md | Service protocol, CQRS, Auth | | model.md | Model, DTO, Error, Enum |

Forbidden

| Anti-Pattern | Fix | |--------------|-----| | Files > 100 lines | Split at 90 | | Protocols in impl files | Move to Protocols/ directory | | ObservableObject | Use @Observable | | Completion handlers | Use async/await | | Missing #Preview | Add preview for every View | | Non-Sendable in async | Use struct with let | | Flat Sources/ structure | Use Features/[Feature]/ |