| name | design-an-interface |
| description | DEPRECATED. Prefer `/prototype` for design exploration and runnable UI variations. Do not use unless user explicitly says `/design-an-interface` or asks for legacy skill. |
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
