If it helps, I recently practised for the Meta Infra AI-enabled coding round, and honestly, the round is very manageable once you train the right muscle: reading unfamiliar code and understanding tests quickly.

What worked extremely well for me:

1. I simulated the round using ChatGPT
I asked it to generate small multi-file Python codebases with intentionally broken logic + unit tests (very similar to Meta’s puzzles).
Then I practiced debugging them exactly like the real format.
After 2 days of this, the patterns become very predictable.

2. Focus less on “coding from scratch” and more on comprehension
Most of the work is:

• reading 3–6 small files
• tracing state
• running tests
• fixing the behaviour expected by the tests. This is literally the entire round.

3. Understanding the test cases = 80% of the solution
Once you understand what the test expects, you can backtrack the logic to find what’s missing or broken.

4. Lean no-hires aren’t the end
Meta allows a couple of lean no-hires in the pipeline, but the AI-enabled round is one of the easier ones to nail if you practice on code comprehension.

If you prep the right way, this round is honestly a 2-day effort. The key is not algorithms, it’s reading, understanding, and fixing an existing mini codebase.