design-an-interface

# Design an Interface Based on "Design It Twice" from "A Philosophy of Software Design": your first idea is unlikely to be the best. Generate multiple radically different designs, then compare. ## Workflow ### 1. Gather Requirements Before designing, understand: - [ ] What problem does this module solve? - [ ] Who are the callers? (other modules, external users, tests) - [ ] What are the key operations? - [ ] Any constraints? (performance, compatibility, existing patterns) - [ ] What should be hidden inside vs exposed? Ask: "What does this module need to do? Who will use it?" ### 2. Generate Designs (Parallel Sub-Agents) Spawn 3+ sub-agents simultaneously using Task tool. Each must produce a **radically different** approach. ``` Prompt template for each sub-agent: Design an interface for: [module description] Requirements: [gathered requirements] Constraints for this design: [assign a different constraint to each agent] - Agent 1: "Minimize method count - aim for 1-3 methods max" - Agent 2: "Maximize flexibility - support many use cases" - Agent 3: "Optimize for the most common case" - Agent 4: "Take inspiration from [specific paradigm/library]" Output format: 1. Interface signature (types/methods) 2. Usage example (how caller uses it) 3. What this design hides internally 4. Trade-offs of this approach ``` ### 3. Present Designs Show each design with: 1. **Interface signature** - types, methods, params 2. **Usage examples** - how callers actually use it in pra...