I want a lightweight Android application that can grab every incoming and outgoing SMS from one phone and instantly push a mirror copy to a second Android device in real time. Only the messages associated with a single SIM/number have to be handled, so no multi-account logic is required. The core of the job is the sync engine: as soon as an SMS event fires on the source phone it should appear on the target phone with the same content, sender, timestamp, and read/unread state. I am open to whatever architecture you find most reliable—Firebase Cloud Messaging, a custom WebSocket backend, or any secure REST gateway—as long as the hand-off feels immediate and works in the background without draining the battery. Please build the app in Android Studio using Kotlin or Java, include clear instructions for both APK installation and Play-store-ready signing, and document any cloud components so I can deploy them on my own server if needed. Deliver the source code, compiled APKs for both devices, and a short read-me so I can reproduce your build. Once installed I should be able to: • grant SMS permissions, • enter the destination device ID or token, • toggle the real-time sync on/off, and everything should “just work”. I will test with a few dozen rapid-fire messages; successful delivery on the second phone with matching metadata will be the acceptance criteria.