# Decide Registry

> When to use the Registry pattern for runtime extensibility.

- Skill: `attac-t/decide-registry` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add attac-t/decide-registry`
- Raw SKILL.md: https://api.skillmd.com/api/skills/attac-t/decide-registry/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: attac-t (https://skillmd.com/u/attac-t)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/attac-t/decide-registry

---


# Skill: Registry

> "Register once, resolve anywhere."

## The Decision

**Use Registry when:**
- Need to add/remove implementations at runtime
- Strategies or handlers are resolved by identifier
- Plugin-like extensibility is required
- UI needs to display available options

**Use Direct DI when:**
- Single implementation per interface
- No runtime discovery needed
- Static, compile-time binding is fine

## The Heuristic

Ask: *"Do I need to discover or extend implementations at runtime?"*

- **Yes, dynamic** → Registry
- **No, fixed** → Direct DI

## The Quick Test

| Scenario                               | Use       |
|----------------------------------------|-----------|
| User selects from available strategies | Registry  |
| Third-party can add implementations    | Registry  |
| Need `all()` or `getOptions()` methods | Registry  |
| One implementation, injected directly  | Direct DI |
| Known at compile time                  | Direct DI |

## The Pattern

```php
class StrategyRegistry {
    public function register(StrategyInterface $s): void;
    public function resolve(string $id): ?StrategyInterface;
    public function all(): Collection;
}
```

## Real-World Examples

For concrete examples from Laravel, Spatie, and production code, see [examples.md](examples.md).