You join a customer's project and must add a feature to a large codebase you have never seen, by tomorrow. How do you work?

Strong answer

Get it running locally or in a dev environment first. Find the entry point for the feature area and trace a single request end to end, using logs, a debugger or an AI coding assistant to explain unfamiliar parts. Read the tests near the code you will touch. Make the smallest change that delivers the feature, following the existing patterns rather than introducing your own. Add or update tests. Ask the owning team a short list of specific questions instead of many vague ones. Leave a short note of what you learned for the next person.

Weak-answer indicators

• Reads the whole codebase first
• Rewrites code to their preferred style
• No tests