Call with the hiring manager. Thought we had a good conversation. Got a call from the recruiter saying they would have to pass because I was not able to speak to certain aspects of the code. Problem was the manager only asked vauge qualitative questions with no follow up on questions about technical implementation or details. I even asked if there was anything I could expand on or clarify and he did not seem interested in technical details, and did not take the opportunity to rephrase his question. He just assumed his bad questions would elicit in depth technical responses in a behavioral/get to know you call. If you want technical details (or really any question) ask the question in a way that tells the answerer what you are looking for. "How did that scale" is vague and does not really get to the heart of what you want to know. "Can you explain the mechanisms you used to make that system scale" gets across that you are looking for more technical details. Either way I would not want to work with a manager that expects you to be able to read his mind to figure out what question he is really asking and even less so one that will not ask clarifying questions when its obvious someone did not read his mind correctly.

Very well structured and organised interview process. There were multiple interview rounds covering systems design, programming, systems deep dive and leadership. The whole process took a bit more than a month, approximately 2 interviews per week.