design-an-interface

> Deprecated: prefer replacement named in description. Keep only for backward compatibility. # Design an Interface "Design It Twice" (A Philosophy of Software Design): first idea rare best. Generate radical different designs, compare. ## Workflow ### 1. Gather Requirements - Problem? Callers? Key ops? Constraints? Hide vs expose? - Ask: "What does this module need to do? Who will use it?" ### 2. Generate Designs (Parallel Sub-Agents) Spawn 3+ agents parallel. Each **radical different** approach, different constraint: - Agent 1: min method count (1-3 max) - Agent 2: max flexibility - Agent 3: optimize common case - Agent 4: inspiration from [specific paradigm] Each output: interface signature, usage example, what hides, trade-offs. ### 3. Present Designs Show sequential: signature, usage, what hides. User absorb each before compare. ### 4. Compare - Interface simplicity (fewer methods, simpler params) - General-purpose vs specialized - Implementation efficiency - Depth: small interface hide complexity (good) vs large interface thin impl (bad) - Ease correct use vs ease misuse Discuss prose, no tables. Highlight divergence points. ### 5. Synthesize Best design often combine insights. Ask: "Which fits your case? Any elements from others worth incorporating?" ## Anti-Patterns - Similar designs waste exercise -- enforce radical difference - Always compare -- value in contrast - Interface shape only -- no implement - Ignore implementation effort in evaluation