Developer Builds AI Finance App Where Model Can Propose But Never Touch Your Data

A developer has built Sable, a React Native personal finance app designed so that all financial data is stored locally on-device in SQLite, with no cloud backend. The app uses OpenAI function calling, but every AI-suggested action — such as logging a payment — is rendered as a 'Review & Confirm' card that only executes when the user manually approves it. This architecture ensures an AI hallucination can produce, at worst, a dismissible card rather than an erroneous ledger entry. Additional features include serialized database writes, an offline-first design, and a daily on-device RAG-powered Morning Briefing that summarizes spending without sending any financial data off the device. The developer argues this 'propose/confirm' pattern is broadly applicable to enterprise domains like healthcare and legal, where AI assistance is valuable but full AI authority over data is unacceptable.