When developing a Android or Flutter app, running flutter run usually overwrites the existing installed version of your app. This is annoying if you want to keep your "Production/Release" version (with real user data) while testing new features on a "Debug" version.

1. The Logic

We need to tell Gradle: "If the build type is Debug, add .debug to the package name."
Original ID: hesham.hcody.az
Debug ID: hesham.hcody.az.debug

2. Kotlin DSL (`build.gradle.kts`)

If your project uses Kotlin DSL (the modern standard), use the code below. This matches the snippet you provided.

android {
    // ... existing config ...
    
    defaultConfig {
        applicationId = "hesham.hcody.az"
        // ...
    }

    buildTypes {
        getByName("debug") {
            // Adds a suffix to the App ID, creating a new app instance
            applicationIdSuffix = ".debug"
            // Optional: Changes the version name so you can spot it easily
            versionNameSuffix = "-debug"
        }
        getByName("release") {
            signingConfig = signingConfigs.getByName("release")
        }
    }
}

3. Groovy DSL (`build.gradle`)

If you are using the older Groovy syntax, the logic is the same but the syntax differs slightly.

android {
    // ... existing config ...

    defaultConfig {
        applicationId "hesham.hcody.az"
        // ...
    }

    buildTypes {
        debug {
            // No '=' sign in Groovy for these properties
            applicationIdSuffix ".debug"
            versionNameSuffix "-debug"
        }
        release {
            // Assuming you defined the signing config above
            signingConfig signingConfigs.release
        }
    }
}