Problem
Design Vercel's core: build, deploy, and serve frontend apps globally at the edge with instant rollbacks.
Requirements
Functional:
- Git push -> build -> deploy
- Serve static + serverless/edge functions globally
- Atomic deploys with instant rollback
- Preview deployments per branch/PR
Non-functional:
- Millions of deployments, global traffic
- Fast cold starts at the edge
- Zero-downtime deploys
Discussion points
- Build pipeline and artifact storage
- Immutable atomic deploys + instant rollback
- Edge network: static CDN + edge/serverless functions
- Preview environments per commit
- Caching/invalidation (ISR) and cold-start mitigation