Google-Based AI Agent Development

Build a Google-based AI agent that answers questions using only four sources: Google Workspace Email, Google Drive for that email, Google Chat (Space), and Contacts. The agent should annotate every answer with a source link and restrict access so only the logged-in Gmail user can interact. Data should refresh twice daily, with a short response latency. The interface should resemble Google Gemini, with text-only inputs and outputs. Please also explain how your solution would improve on the out-of-the-box Google Gemini experience. Note - To avoid taking too much of your and my time, I want to send an approximate hourly effort range and your clarification questions that can cause your estimate to vary.