Day 11 — Cost Optimization (AWS + LLM)

[PunithVT]

Day 11. Both AWS and LLM bills surprise people every month. Doing this once properly so we know the levers in advance and can build cost-conscious systems from day one.

Topics to cover:

1. AWS cost basics — Cost Explorer, Budgets, tagging strategy that actually works
2. Compute levers — Savings Plans, Spot, ARM/Graviton, right-sizing Lambdas
3. Data levers — S3 storage classes + Intelligent-Tiering, RDS reserved, CloudWatch retention
4. LLM cost levers — prompt caching, model routing (haiku → sonnet), batch APIs
5. Semantic caching, response caching, and rule-based pre-checks before the model runs

Plan: Chandana on the AWS cost levers (Cost Explorer, Savings Plans, S3 tiers), me on the LLM cost levers (caching, routing, budgets), both writing up the actual bill numbers we hit.