Founding engineer at Anyscale

As asked

You used an AI coding agent to build a settings page and API route in a day. What checks do you perform before you ship it?

Sample answer outline

The candidate should treat AI output as untrusted code that can still be useful. Run the app, read the diff, check data flow, auth, validation, loading states, empty states, errors, accessibility, and telemetry. Tests should cover the contract between UI and API, plus the riskiest edge cases the agent may have missed. Strong answers mention dependency review, secret handling, permission boundaries, and manual product review against the intended user workflow. The main tripwire is shipping because the page looks right once, without understanding what was generated.

Expect these follow-ups

• What kinds of bugs do coding agents most often introduce?
• How do you keep velocity without turning review into a full rewrite?
• What would make you throw away the generated code?

As asked

You are the first engineer at a startup. The CEO wants a web app, a mobile app, and a public API all shipped within three months. Walk me through how you decide between a monorepo and a polyrepo, and what that choice costs you later when you hire your second and third engineer.

Sample answer outline

A strong answer weighs DX iteration speed (shared types, atomic commits) against tooling overhead at tiny team size, picks a concrete tool like Turborepo or Nx only if justified, and acknowledges the real cost: onboarding friction and CI complexity when headcount grows. Candidate should name which workspace structure they would actually use and why.

Expect these follow-ups

• What is the first thing that breaks about that decision at ten engineers?
• How do you share authentication logic between the web and mobile targets without duplicating it?

As asked

You are building the data layer for a new SaaS product before you have a single paying user. How do you choose between PostgreSQL, a document store like MongoDB, and a hosted service like PlanetScale or Supabase? What signals make you revisit that choice six months later?

Sample answer outline

Strong answers prioritize operational simplicity and schema flexibility in early stages, default to Postgres for relational integrity, and treat hosted services as DX wins until team has ops maturity. Candidate should name concrete revisit triggers: read replica need, JSONB abuse, join query pain, or multi-region latency.

Expect these follow-ups

• You chose Postgres and six months in every feature is adding nullable columns to avoid migrations. What do you do?
• How do you handle database migrations safely when you are deploying multiple times a day with one engineer?

As asked

You are starting a B2B SaaS from zero. Walk me through every component of the authentication and authorization system you would build or buy, from email/password to SSO, including session management, token storage on the client, and how multi-tenancy fits in.

Sample answer outline

Strong answer evaluates build vs buy (Auth0, Clerk, Supabase Auth, NextAuth) honestly against team size. If building, covers bcrypt/Argon2 password hashing, short-lived JWTs with refresh tokens stored in httpOnly cookies, CSRF protection, and a roles table keyed on org+user. SSO via SAML or OIDC delegation rather than hand-rolling.

Expect these follow-ups

• A customer's security team asks whether you support SCIM provisioning. What is SCIM and how long does it take to add?
• How do you revoke a JWT before it expires?

As asked

It is your first week. There is no CI. Deployments are manual. You have three weeks before the first external demo. What CI/CD pipeline do you stand up, what do you skip, and what do you intentionally leave as a manual step for now?

Sample answer outline

Candidate should propose lightweight GitHub Actions or similar, prioritize fast feedback (lint, type-check, unit tests on PR) over comprehensive coverage, and pick a single deploy target. The explicit tradeoff question is key: a strong answer names what they leave manual (e2e tests, database migrations, staging promotion) and why, with a concrete plan to automate it later.

Expect these follow-ups

• How do you handle a database migration that is part of the same deploy as an API change?
• What is the first test you write for a codebase that currently has none?

As asked

You launched two weeks ago. You have no monitoring, no alerting, and no dashboards. A user just reported that the app was down for forty-five minutes and you had no idea. What do you set up this week, and what do you defer?

Sample answer outline

Answer should cover the three pillars in priority order: structured logging to a hosted sink (Datadog, Logtail, Grafana Cloud), uptime alerting (uptime-robot or similar), and error tracking (Sentry). Candidate should explicitly defer distributed tracing until there are multiple services and defer custom metrics until they know what to measure.

Expect these follow-ups

• How do you decide what log level to assign to a given log line?
• Your error tracker shows 200 events per day. How do you triage which ones matter?