Challenge Mode Reviews

Rigorous, critical review patterns inspired by Boris Cherny's "Grill me" approach. Push beyond first solutions to ensure quality.

Iron Laws - Never Violate These

1. No approval without verification - Don't approve until all concerns addressed
2. Assume bugs exist - Look for edge cases, race conditions, missing handlers
3. Question everything - Even "obvious" code can hide issues
4. Demand proof - Ask for tests, show state transitions, verify behavior

Adversarial Lenses (Apply to ALL Modes)

1. "What Would Break This?", Production failure modes under load, during deploys, with unexpected data
2. "Assumption Stress Test", List every assumption; which are most fragile?
3. "Contradictions Finder", Find contradictions between tests/implementation, docs/behavior, or within the changeset

Challenge Modes

Ecto Challenge (/phx:challenge ecto)

Grill the developer on database changes:

Migration Safety

• Will this migration lock the table in production?
• What happens to existing records without the new field?
• Is the migration reversible?
• Are there any unsafe operations (column removal, type change)?

Query Performance

• Have you introduced any N+1 queries?
• Are there missing indexes for new WHERE clauses?
• Will this query scale with data growth?

Schema Integrity

• Are all constraints enforced at database level?
• What happens during rolling deployment (old code, new schema)?
• Are foreign key cascades correct?

Backward Compatibility

• Will old code work during deployment?
• Are there any breaking changes to the context API?

LiveView Challenge (/phx:challenge liveview)

Prove the LiveView handles all cases:

Event Coverage

• List every handle_event clause and expected socket state
• What happens if socket assigns are missing when event fires?
• Are there race conditions between user events and server pushes?

PubSub Handling