One month elapsed between each of these steps: applying, receiving and submitting a written technical questionnaire, my first interview, and my final interview.

The delays and failure to respond in between each step were frustrating. They asked me to be patient, stating they were very busy.

When they finally responded, my interviews went wonderfully, and I was surprised not to have received an offer. They gave no specific reason, except that they had many qualified candidates and limited positions.

Re-implement a (specific) feature of Git in a language of your choice.

When communicating using text, how do you avoid ambiguities and miscommunication with the lack of in-person social cues?

Extend a (contrived) Rails application with a new feature. Identify and resolve potential performance issues.