Simantic Bot reviews firmware inside GitHub pull requests for embedded teams. It compiles the change, generates input scenarios from the diff, runs the firmware on simulated microcontrollers and system-on-chips, and treats any gap between expected and simulated output as evidence of a bug in the source. The target is interrupt service routines, peripheral timing, and runtime memory, the failures software reviewers such as Greptile miss because they never execute the binary against a chip. Scenarios can include sensor readings and wireless traffic, and the bot posts what it tested, what failed, and suggested fixes. In the launch demo, a pull request on an STM32F446 flight controller replaced a fixed timer prescaler with a value derived from the APB1 bus clock. After a comment tagging the bot, the review reported that the timer period ran twice as fast as the code intended, because that timer clock defaults to twice the APB1 frequency. It commented on the line and suggested using the timer clock instead. The report lists the scenarios, the expected outputs, and a link to a dashboard with the simulation run. Simantic is a Y Combinator Fall 2026 company in Waterloo building simulation so firmware can be tested without a physical board. CEO Seungmin Hong previously wrote firmware at Tesla, Simbe Robotics, and Rapyuta Robotics. CTO Ahnaf Shahriar previously worked on Neuralink's implant and charger firmware and on Tesla's Dojo and Autopilot hardware. The reviewer uses the same platform as Cloud Sim, which runs firmware images on virtual microcontrollers from CI, a terminal, or an API.