Cossi: AI Chief of Staff

Cossi is a private AI Chief of Staff that runs entirely on your iPhone. No cloud. No server. No subscription required for the core app.

WHAT IT DOES EVERY MORNING Cossi reads you a spoken brief when you wake up: • Today’s meetings and any scheduling conflicts • Which important relationships are going cold — based on your local calendar and email headers • Open decisions that have sat unresolved too long • High-priority tasks that need action today

The brief is generated on-device from your own data. Nothing is sent to a server.

RELATIONSHIP INTELLIGENCE Cossi tracks who matters in your world and surfaces when those relationships are drifting — based purely on local email headers and calendar attendance. No content analysis. No cloud processing.

ENCRYPTED VAULT Store API keys, seed phrases, passwords, and private notes in a vault encrypted with AES-256-GCM. The encryption key is derived from your 24-word seed phrase via HKDF — it never leaves your device, and Cossi never has access to it.

HUMAN-APPROVED OUTREACH When Cossi drafts an email or books a meeting, it waits for your explicit approval before sending anything. You remain in control of every outbound action.

PRIVACY BY ARCHITECTURE • AI model runs on-device (llama.rn + DeepSeek R1 1.5B) • Calendar and email data never transmitted • Post-quantum auth: ML-DSA-65 (CRYSTALS-Dilithium) — no password, no breach risk • Direct IMAP/SMTP — no OAuth proxy, no email middleman • Recovery via BIP-39 24-word mnemonic — no email OTP

PRO FEATURES Upgrade to connect Claude or GPT-4 as your AI provider using your own API key. Your key goes directly from your phone to the AI provider — it never touches our servers.

Cossi is built on the principle that an AI with access to your most private data should run on your device, not someone else’s cloud.