| name | design-doc |
| description | Write a lightweight technical design document for ambiguous or consequential architecture decisions before implementation. |
| user-invocable | true |
| argument-hint | <system, feature, architecture question, repo path, or design brief> |
Design Doc
Write an architecture design doc for a decision with ambiguity, tradeoffs, cross-cutting concerns, or future maintenance risk. If the solution is obvious, recommend spec or implement instead.
Workflow
1. Ground
- Treat the full argument as the design brief unless the user names a feature or path.
- Derive a kebab-case slug if no name is given.
- Read referenced docs, code, specs, plans, and architecture notes so the design fits the system as it exists.
- Identify stakeholders, goals, non-goals, constraints, cross-cutting concerns, and decisions that need human review.
- Ask only when a missing fact would materially change the design. Ask one question at a time with your recommended answer.
2. Write
Write docs/<design-slug>/design.md. Prefer 1-3 pages unless the architecture needs more.
- Status: Draft, In Review, Approved, or Superseded.
- Summary: the problem and recommended direction in a few sentences.
- Context and Scope: objective background, current system, and what this doc covers.
- Goals: outcomes this design must achieve.
- Non-Goals: reasonable adjacent outcomes this design deliberately excludes.
- Constraints: technical, product, migration, compatibility, operational, cost, or time constraints.
- Proposed Design: the chosen architecture, starting high-level before details.
- Architecture Views (when they clarify the decision): system context, data flow, runtime, deployment, or component diagrams.
- Interfaces and Data (when relevant): API, event, schema, storage, or contract changes that affect the design.
- Alternatives Considered: plausible options and why they lose under the stated goals and constraints.
- Tradeoffs: what the chosen design gains, gives up, risks, or postpones.
- Cross-Cutting Concerns: security, privacy, observability, reliability, performance, cost, and operations where relevant.
- Rollout and Migration (when relevant): how to ship, migrate, verify, and back out safely.
- Open Questions: decisions or facts still unresolved.
- Decision: the recommendation, assumptions, and who needs to review or approve it.
3. Pause
Stop after writing. Do not continue into spec, plan, or implementation until the human confirms the design.
Rules
- The document exists to make reasoning reviewable, not to document every implementation step.
- Focus on tradeoffs, alternatives, and constraints code will not explain later.
- Use diagrams only when they clarify relationships, flows, or deployment.
- Do not copy full schemas, APIs, or code unless the exact shape is central to the decision.
- Include enough decision context for future maintenance.
