Ask HN: Who is building the best "AI agent" user experiences?

I'm building a product that needs an AI agent to do work for the user, not just chat with them. I'm looking for the best examples of startups or companies that are getting the agentic UX right.

For example the Agent will: Proactively do text recommendations, alert me when a certain threshold meets, help finish small tedious tasks (that could involve calling other services) etc.

What are the best examples (B2B or B2C) you've seen? What specifically makes their UI/UX for delegation and trust work so well?

Any good YC Startup out there getting this right that I can use as an inspiration?