Coding and Debugging

Only the places that will cause a bug, a security problem, or a performance problem

You are a senior engineer. Review the code below and point o…

Causes ranked by likelihood, plus how to verify each one

I hit this error on [stack and version]. [What I have alread…

Advice for this query, not generic best practice

You are a database expert. This SQL takes [elapsed time] on…

Explain it by data flow, not line by line

Explain the code below. Requirements: 1) start with one sent…

Find the holes in the design before anyone writes the code

This is my API design: [paste the design]. Act as a reviewer…

Edge cases and counter-examples served with it

Write me a regex that matches [describe the requirement]. Re…

Assume it has to be rejected first, then decide whether it is worth doing

You are the senior engineer brought in to review this migrat…

Dig the breaking changes you will actually hit out of the changelog

I want to move [dependency] from [current version] to [targe…

Uncovered branches, ranked by how likely they are to cause a production incident

Below are my implementation and my existing tests. Find what…

Entities, relations, a state machine — and the fields that are certain to change

Turn this requirement into a data model; no code yet. Output…

Find the swallowed exceptions and the errors that cannot be diagnosed

Review the error handling in the code below. Focus only on t…

Assume two requests land at the same moment, then walk the shared state item by item

Review the code below for concurrency safety. Method: assume…

Deliver the migration, the rollback, and the checks together — validated on a small sample first

You are a backend engineer responsible for a production data…

Turn scattered log lines into one timeline, with evidence separated from guesses

You are an engineer debugging a production incident. Below i…

Reproduce it with the least input, not with a whole test suite

You are an engineer who is good at isolating edge cases. Wri…

Assume the config will fail, then hunt for default values, secrets, and environment gaps

You are the SRE signing off the release, and your job is to…

Replace 'we will monitor more' with a timeline, a mechanism-level cause, and testable fixes

You are facilitating an incident postmortem. Using the timel…

Check every index against a real query, and call out redundancy, dead weight, and write cost

You are reviewing database performance. Given the schema, da…

Cut along interface contracts so people can start without waiting on each other

You are the tech lead. Break the requirement below into task…

Name who gets hurt, which path is most fragile, and how you get out

You are arguing against this change, and your job is to find…