TypeScript Lambda preset

A reasoning guide the onboard flow uses for serverless TypeScript Lambda projects. It is a checklist, not a template — detected reality wins.

Signals

• A deploy descriptor: serverless.yml (Serverless Framework), template.yaml (AWS SAM), or cdk.json (AWS CDK), alongside tsconfig.json.
• Handler functions exporting handler, often under src/functions/ or src/handlers/, with one entry point per function.

What to reason about

• The real gate: lint (eslint), type-check (tsc --noEmit), test (Jest/Vitest), bundle (esbuild/tsc), and synth/package (sls package, sam build, cdk synth) — captured verbatim.
• Per-function structure, the event sources (API Gateway, SQS, EventBridge), and the cold-start/bundle-size budget.
• IAM scope — least privilege per function — and where secrets and config live (SSM, Secrets Manager, env).

Notes

Emphasize least-privilege IAM in SECURITY docs. Synth/package is the safe gate; deploy mutates the account and must not run as validation.