How to Strip Sensitive Data Before It Hits Your LLM

You built an AI agent that logs into your bank, navigates to billing, and extracts your bill amount. Smart. But now Claude is reading your full name, home address, account numbers, and partial SSN — all sent through an API you don't control. That's not a pipeline. That's a liability. Here's how I solved it with four regex patterns and an open-source library most people have never heard of. The Context I'm building Bill Analyzer — an agentic system that automatically logs into utility and financial sites, navigates to billing pages, and extracts what I owe and when it's due. It uses: Playwright for browser automation Claude (Haiku) as the AI agent for navigation and extraction 1Password CLI for credential management The architecture has two phases: Login Agent — navigates login flows with credentials handled opaquely (the agent never sees passwords) Extract Agent — reads post-login pages to find billing data The extract agent needs to read the page to find dollar amounts and due dates.