Architecture maturity — start small, grow
The same platform at four maturity stages. Stage 1 is an MVP you ship in a week (Vercel + Cloud Run + Cloud SQL — the smallest proven stack). Advance the stage to add only what that stage needs; future components stay dimmed so you see the roadmap without the overwhelm. This is the antidote to over-engineering: nothing is added before its time.
Stage 1 · MVP (ship it). The smallest proven stack: a Vercel frontend, one Cloud Run service, one Cloud SQL database. You can demo quote→bind end-to-end. Add nothing else yet.
Stage 2 · Real product. Add what makes it a real insurance product: a product-version store (versioned by date), the external cat-model for peril scores, Pub/Sub for the scorecard fan-out, and a WAF at the edge (quote endpoints get scraped).
Stage 3 · Trust & AI. Now earn trust: make the lifecycle event-sourced with a hash-chained audit log + WORM anchor; add the propose-only RAG agent; split the monolith (the single all-in-one app) into per-flow services behind a BFF; lock down secrets with Secret Manager + WIF.
Stage 4 · Scale & resilience. Only now: go multi-region behind a global load balancer, move to AlloyDB (HTAP, Profile B) for heavy read fan-out + operational analytics, and add DR (RTO/RPO) + SLOs/observability. Same Postgres interface (identical SQL), so nothing breaks.