Image: Sentient OS
Why it mattersReply tools often ask you to paste your context first. On-device context removes the paste step and keeps content on your Mac.
Using an AI to draft a reply usually starts with telling the AI who you are. Sentient OS says you should not have to. Its Mac app reads your notes, emails, messages, calendar and files on-device while you sleep. It then uses that context to draft replies in your voice. The product is in Y Combinator's Fall 2026 batch.
Two features sit on top of the overnight context. Double-tap the right Command key in any reply box. The app then writes the reply in your style. Click the Mac's notch and ask the app to finish a task. A tool it calls Sidekick picks up with its own cursor across your apps and browser. That is per the company's own launch page.
What runs on the Mac, and what does not
The context model runs locally. Sentient OS says its own inference stack works on Apple Silicon Macs with 8 GB of RAM. That lets it run hours of overnight analysis with no cloud bill. Your knowledge lives in an editable Markdown folder on your Mac. You can open it, correct it, and point other AI tools at it.
The task step can run in the cloud. Sidekick calls your existing ChatGPT or Claude subscription for the actual task. The company says cloud features receive the context from your Mac for that call. You can also pick a compatible local model instead. The app is open source, per the company.
The traction, in the company's own numbers
Sentient OS says more than 10,000 Mac users have signed up. It also says people at more than 130 companies use it, Adobe among them. Those are its own figures and are not audited by any outside party. The home page quotes five posts from Reddit's r/macapps community, each with the user handle. One post is listed there as the subreddit's "top post of the month".
The Y Combinator launch page had only 3 votes at the time of writing. The traction above does not come from YC.
Who is building it
The two founders named on the launch page are Aditya Durga and Jesai Tarachandani, ages 20 and 18. Aditya is CTO. The page says he previously built AI agents at IBM. Jesai is CEO. Those are the company's own stated biographies.
What this changes for someone using AI to write
The paste step moves off the keyboard. A careful user of ChatGPT or Claude pastes the thread, a style guide, and the person on the other end. Each new reply means a new paste. Sentient OS keeps that context on the Mac and feeds it to the reply. The user types two keys instead. The content never leaves the machine for the local step. That matters when the thread holds something confidential.
Three things stay unverified. The 10,000 user and 130 company figures come from the company. Adobe has not confirmed its name appears there. The eight-gigabyte memory floor is a bar the company sets for its own stack. No outside measurement compares it with a competing on-device model. A buyer should test the overnight pass on a representative Mac before trusting the context quality.
Source
Sentient OS: On-device AI that knows you and takes over your work, Y Combinator Launches. Sentient OS, the company.
This item was written by an AI system from the linked source. Reveneau is responsible for what it publishes.
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