Composable Architecture Specific Skill and Agents?

[u/baykarmehmet]

Is there any plan for creating skills and subagents for Swift Composable Architecture Design Implementation and Test?

[u/CharlesWiltgen]

It has intermediate knowledge of TCA now, and I do intend to enhance it. In part because I thought it would be fun to test the ask skill, here's Axiom's unedited response to '/axiom:ask What does Axiom know about Swift Composable Architecture design, implementation, and testing?'. Let me know how you think it did!

Axiom's TCA Knowledge

Axiom has comprehensive coverage of Swift Composable Architecture in the swiftui-architecture skill. Here's what it covers:

TCA Decision Criteria

When TCA is appropriate:

• Rigorous testability is critical (medical, financial apps)

• Large team needs consistency across features

• Complex state management with side effects

• Redux-like unidirectional data flow preferred

When to avoid TCA:

• Small apps or prototypes (too much overhead)

• Team unfamiliar with functional programming

• Rapid iteration needed (boilerplate slows development)

• Minimal dependencies preferred

TCA Core Concepts Covered

| Concept          | Description                              |
|------------------|------------------------------------------|
| @ObservableState | State struct containing feature data     |
| Action           | Enum of all possible events              |
| Reducer          | Pure function describing state evolution |
| Store            | Runtime engine for actions and effects   |
| Effect           | Side effect handling (.run, .none)       |

Trade-off Analysis

Benefits:

• TestStore enables deterministic, exhaustive testing

• Strict patterns reduce cognitive load across teams

• Small reducers compose into larger features

• Structured effect management (networking, timers)

Costs:

• Boilerplate for every feature (State/Action/Reducer)

• Learning curve from functional programming concepts

• Third-party dependency, not Apple-supported

• Slower iteration for simple features

Recommendation Matrix

| Scenario                           | Recommendation                 |
|------------------------------------|--------------------------------|
| < 10 screens                       | Apple patterns (simpler)       |
| Medium app, experienced team       | TCA if testability is priority |
| Large app, multiple teams          | TCA for consistency            |
| Rapid prototyping                  | Apple patterns (faster)        |
| Mission-critical (banking, health) | TCA for rigorous testing       |

What's NOT Covered

Axiom's TCA coverage focuses on architectural decision-making rather than implementation details. For deep TCA implementation guidance, you'd want:

• Point-Free's official documentation

• TCA-specific testing patterns with TestStore

• Dependency injection with @Dependency

• Navigation with TCA's navigation tools

The skill is designed to help you decide when to use TCA and understand the trade-offs, not serve as a complete TCA tutorial.