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The 5-Phase System Design Framework
Use this skeleton for every scenario. It maps directly to how Google FDEs run customer engagements.
5-Phase System Design Flow
flowchart LR A["1. RESTATE
Confirm understanding"] --> B["2. CLARIFY
3-5 sharp questions"] B --> C["3. ASSUMPTIONS
State explicitly"] C --> D["4. DESIGN
Ingestion → Model →
Agent → Surface"] D --> E["5. NON-FUNCTIONAL
Security, Scale,
Ops, Cost"] style A fill:#fff7e6,stroke:#c47e0a,stroke-width:2px style B fill:#f0f7ff,stroke:#2b6cb0,stroke-width:2px style C fill:#f0fff4,stroke:#2d8659,stroke-width:2px style D fill:#fff0f5,stroke:#c73e6e,stroke-width:2px style E fill:#f5f0ff,stroke:#7b4bb3,stroke-width:2px
| Phase | Name | Description |
|---|---|---|
| 1 | RESTATE | "Let me play back what I heard..." — Confirm understanding. |
| 2 | CLARIFY | 3-5 sharp questions before designing. "Who owns the data? What's the latency SLA? What's acceptable cost-per-request?" |
| 3 | ASSUMPTIONS | State explicitly: "I'll assume English-only for V1, GCP-only, Gemini 2.5 family. Flag if any should change." |
| 4 | DESIGN | Walk through in layers: ingestion → model serving → agent orchestration → user surface. |
| 5 | NON-FUNCTIONAL | Security, scale, ops, cost, risks. "Now let me talk about how this scales, stays secure, and how we know it's working." |