Rahil Pirani

We just shipped Second Brain 3.4.0, and since the last Product Hunt update was 3.0, I wanted to share what has changed.

The biggest addition in 3.4 is Projects.

If you use AI across different products, clients, codebases, or areas of your life, one giant pool of memory can get messy fast. Projects let you keep related memories together, so your AI can pull from the right context without you having to explain everything again.

I recently built a benchmark for an AI retrieval system. The most revealing cases weren t the ones where the right answer ranked second instead of first. They were the ones where no relevant context existed at all.

A system that confidently retrieves something vaguely related can look functional while being completely wrong. So I added absence cases where the correct result is nothing.

It changed how I judge retrieval quality. Finding context matters, but knowing when there isn t any might matter more.

If you re testing an AI feature, do your evals include cases where the correct answer is I don t know ?

While building shared memory for teams, I spent a lot of time thinking about what AI should know. The more uncomfortable question was what should never enter the shared layer.

Private notes? Feedback about a teammate? A half-formed strategy?

Where would you draw the line?