Productivity Reminder Mobile App

I need a lightweight mobile application whose single purpose is to help me stay on top of my schedule by sending timely reminders. Think of it as a pocket-sized personal assistant: I open the app, set a date and time (optionally a repeat rule), get a push notification when it’s due, and mark it done—nothing more complex than that.

Core expectations
• Native or cross-platform build that runs smoothly on both Android and iOS.
• Clean, distraction-free interface that lets me add, edit and delete reminders in just a couple of taps.
• Reliable local push notifications, even if the device is offline.
• Source code handed over with concise build instructions so I can compile future versions myself.

Nice-to-have (not mandatory, but let me know if it’s easy for you)
– Simple calendar view to see upcoming reminders at a glance.
– Dark/light mode that follows system settings.

Handing me an installable build (APK + TestFlight/IPA) alongside the repo will complete the job.