An engineering project deep dive should reconstruct a decision, not reward a presentation. Ask the candidate to explain one project from the original problem through implementation and operation, then distinguish their contribution from the team's.
This format is useful when a startup needs engineers who can own more than an isolated coding task.
Send a short preparation note
Ask candidates to choose a project they know well and can discuss without confidential details. Slides are optional. A verbal explanation or a simple diagram should be sufficient.
Explain that you will explore tradeoffs, individual responsibilities, collaboration, and what happened after release. Do not ask for private repositories, internal dashboards, or customer records.
Follow the project through five stages
| Stage | Core question | Useful follow-up |
|---|---|---|
| Problem | What needed to change? | Who experienced the problem? |
| Alternatives | What approaches did you consider? | Why reject the strongest alternative? |
| Execution | What did you personally build or decide? | What depended on another person? |
| Release | How did you know it was ready? | What could have failed? |
| Operation | What happened afterward? | What would you change now? |
Stay with one example long enough to understand it. Jumping between impressive projects can conceal the absence of detail.
Probe one tradeoff
Choose a decision the candidate actually owned. Ask what constraint mattered, what evidence they had, and what they could not know at the time.
Then change a relevant constraint: fewer users, a smaller team, stricter reliability needs, or a shorter delivery window. Ask whether the original decision still holds.
This is a reasoning exercise, not a demand to redesign an entire system on the spot. Give the candidate time to state assumptions and revise an answer.
Separate missing evidence from negative evidence
A candidate may not have owned deployment because a different team had that responsibility. Record that operational ownership is untested; do not invent a failure.
If the role requires that skill, assess it separately with a relevant scenario. Likewise, distinguish an unsuccessful project from poor judgment. A sensible decision can produce an unfavorable result under uncertainty.
Write a compact evidence record
Use this structure:
- Responsibility the candidate personally owned.
- Decision and alternatives considered.
- Evidence that informed the decision.
- Result and how the candidate learned about it.
- Remaining question for this role.
Avoid adjectives such as “brilliant” without supporting behavior. The record should let an interviewer who missed the conversation understand the conclusion.
Combine this interview with a product judgment discussion or a reliability scenario, depending on the actual mandate.