Prepzio Blog

You Can Vibe-Code the Feature. Can You Defend It Live?

August 25, 20264 min read

ai
interview
junior-developer
vibe-coding

The agent scaffolds the route. It writes the tests. It opens a diff that looks like a mid-level PR.

You merge it. Standup sounds great.

Then the live round starts. Forty-five minutes. Screen share. Someone says: "Walk me through this change. Why this shape? What did you reject?"

You scroll your own diff and stall.

That is the vibe-coding hangover. The tools got you the feature. They did not get you the explanation.

Vibe coding is a workflow, not a personality

Andrej Karpathy named it: you describe the outcome in natural language, an agent (Claude Code, Cursor Agent, Copilot agent mode, Windsurf) plans and edits, and you accept a lot of what comes back.

In 2026 that is how a lot of real work happens. Refusing every agent is not a moral high ground. It is often just slower.

The trap is treating accepted output as owned work. Hiring loops noticed. Some now want the agent in the room. They are not scoring keystrokes. They are scoring whether you stayed in charge of the result.

Two rooms, one failure mode

You will meet both formats this year. They look opposite. They punish the same gap.

Room A: "AI is allowed"

CoderPad, a hosted Gemini, Claude in the sidebar, your usual IDE. The interviewer watches you prompt, read, and verify.

The fail is not "you used the model." The fail is:

you paste a whole solution and never read it
you re-prompt until green without a hypothesis
you cannot say what you would throw away in the diff
you skip tests because "the agent said it works"

"AI is allowed" is the harder round if your only move is let the model cook. Speed without narration reads as junior. Verification reads as hireable.

Room B: "Close the assistant"

No Claude. No Copilot. A bug, a small feature, or "explain this function."

If every week of practice was agent-on, this room feels like a different job. You did not get worse overnight. You never trained the muscle the room is scoring: reconstruct the idea without the scaffolding.

What they are actually watching

Not "did you invert a tree from memory." More often:

Did you decompose before you generated? A one-line "build the feature" prompt dumps a pile you cannot defend. A three-step plan (shape the data, happy path, one failure) gives you something to narrate.
Did you read the diff like a reviewer? Agents hallucinate checks, skip auth, name things you would never ship. Catching one real problem in generated code is a stronger signal than typing a perfect loop.
Did you verify? Run it. Add a test the agent did not volunteer. Say what would break if the input is empty.
Can you tell delivery from practice? Shipping with a wide agent is fine. Calling that "I learned the system" is not.

If you cannot name one thing you would reject in the last agent PR, you did not review it. You rented it.

A drill that takes one ticket

Pick a change you vibe-coded this week. Tomorrow, without the chat transcript:

Restate the ticket in two sentences (in, out, one edge case).
Sketch the approach from memory. Pseudocode is enough.
Open the diff and mark three lines: one you understand, one you would rewrite, one you cannot explain yet.
Explain the rewrite out loud. If you freeze, that line is the practice, not the next prompt.

On learning days, cap the agent: one file, or one function. On shipping days, go wider, but label those days delivery. Do not file them under growth.

Where Prepzio fits

Prepzio is not an interview cheat sheet and it is not another agent. It is short practice for juniors who already ship with AI and still freeze when asked why.

Hint ladders instead of dumped solutions. Feedback on how you think. A read on whether you are getting more independent on the same class of problem, not just faster at prompting.

If the last live round was you scrolling a diff you could not narrate, that is the gap.

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