Swift Architecture Skill

---

name: swift-architecture-skill description: Agent Skill for Swift architecture design and implementation patterns, with architecture-specific playbooks and review checklists. Use when designing new features, refactoring existing modules, reviewing pull requests, or debugging maintainability issues in SwiftUI/UIKit projects and you need concrete guidance for MVVM, MVI, TCA, Clean Architecture, VIPER, or Reactive patterns.

---

Swift Architecture Skill

Overview

Use this skill to pick the best Swift architecture playbook for SwiftUI/UIKit codebases and apply it to the user’s task.

Workflow

Step 1: Analyze the Request Context

Before selecting an architecture, capture:

task type (new feature, refactor, PR review, debugging)

UI stack (SwiftUI, UIKit, or mixed)

scope (single screen, multi-screen, app-wide)

existing conventions to preserve

Step 2: Select the Architecture

If the user explicitly names an architecture, treat it as the initial candidate and run a fit check before committing:

validate against UI stack fit (SwiftUI/UIKit/mixed), state complexity, effect orchestration needs, team familiarity, and existing codebase conventions

if it fits, proceed with the requested architecture

if it mismatches key constraints, explicitly explain the mismatch and recommend the closest-fit alternative from references/selection-guide.md

if the user still insists on a mismatched architecture, proceed with a risk-mitigated plan and state the risks up front

When no architecture is named, load references/selection-guide.md and infer the best fit from stated constraints (state complexity, team familiarity, testing goals, effect orchestration needs, and framework preferences). Explain the recommendation briefly.

Architecture reference mapping:

MVVM → references/mvvm.md

MVI → references/mvi.md

TCA → references/tca.md

Clean Architecture → references/clean-architecture.md

VIPER → references/viper.md

Reactive → references/reactive.md

Step 3: Analyze Existing Codebase (When Applicable)

When code already exists:

detect current architecture and DI style

note concurrency model (async/await, Combine, GCD, mixed)

align recommendations to local conventions

Step 4: Produce Concrete Deliverables

Read the selected architecture reference and convert its guidance into deliverables tailored to the user's request:

File and module structure: directory layout with file names specific to the feature

State and dependency boundaries: concrete types, protocols, and injection points

Async strategy: cancellation, actor isolation, and error paths

Testing strategy: what to test, how to stub dependencies, and example test structure

Migration path (for refactors): incremental steps to move from current to target architecture

UI stack adaptation: where SwiftUI and UIKit guidance should differ for the chosen architecture

Step 5: Validate with Checklist

End with the architecture-specific PR review checklist from the reference file, adapted to the user's feature.

Output Requirements

Keep recommendations scoped to the requested feature or review task.

Prefer protocol-based dependency injection and explicit state modeling.

Flag anti-patterns found in existing code and provide direct fixes.

Include cancellation and error handling in all async flows.

For explicit architecture requests, include a short fit result (fit or mismatch) with 1-2 reasons.

For mismatch cases, include one closest-fit alternative and why it better matches the stated constraints.

When writing code, include only the patterns relevant to the task — do not dump entire playbooks.

Treat reference snippets as illustrative by default; add full compile scaffolding only if the user asks for runnable code.

Ask only minimum blocking questions; otherwise proceed with explicit assumptions stated up front.

When reviewing PRs, use the architecture-specific checklist and call out specific violations with line-level fixes.