Your Mac reads your life at 3 AM, then does your grunt work

What it does

Sentient OS is a macOS app that wakes your Mac at 3 AM, reads new files, screenshots, WhatsApp, iMessage, Notes, and email from their local databases, and distills them into an Obsidian-style markdown knowledge base stored only on disk. A local Gemma 4 E4B model triages items on-device: junk and sensitive data are dropped with zero trace, while clean summaries are kept. Each morning, it uses your own ChatGPT or frontier model subscription to draft proactive cards—replies, reminders, research—drawn from that deep personal context. A global Sidekick notch interface lets you ask it to finish tasks in your own apps and browser via computer use, grounded in the same knowledge base.

The interesting bit

The privacy architecture is designed to remove the vendor’s ability to see your data, not just their willingness: there are no accounts, no Sentient API keys, and no servers holding your raw data. The optional cloud MCP relay uses zero-access AES-256-GCM encryption where the key never leaves your Mac, and the entire stack is open source under AGPL-3.0. Frontier model compute runs through your own Codex CLI and OpenAI subscription, not a hosted proxy.

Key highlights

• Runs a custom LiteRT-LM inference engine on Apple Silicon, optimized with KV-cache reuse, flash attention, and speculative decoding to fit into 8 GB of RAM.
• Decodes proprietary Apple data formats directly—typedstream, protobuf, WAL-safe SQLite reads—without relying on Spotlight to ingest iMessage, Notes, and WhatsApp.
• Proactive morning cards draft actual work using your own frontier-model subscription; the only actions taken are ones you explicitly click to fire.
• Sidekick offers global computer-use control of your logged-in apps and browser from a notch-activated HUD that transcribes speech on-device.
• Optional cloud MCP mirror is off by default; if enabled, your Mac encrypts the knowledge base before upload and the relay holds only ciphertext with no decryption key.

Caveats

• Requires macOS 15+, Apple Silicon, and about 10 GB of disk space; the on-device model is a 3.7 GB download.
• The free consumer model is subsidized by a future enterprise pivot; the README is explicit that companies will eventually pay for a workplace license.
• Frontier model features rely on your existing OpenAI subscription or Codex CLI setup; they are not self-hosted.

Verdict

Worth a look if you want a local, privacy-obsessed second brain that actually controls your Mac instead of just chatting. Skip it if you don’t trust any software to read your iMessage database, or if you’re not on Apple Silicon.