# nateshmbhat/flutter-multi-module-app architecture

> Architecture diagram of the GitHub repository nateshmbhat/flutter-multi-module-app, generated by GitDiagram from its file tree, README and a sample of source files (last updated 2026-06-26). It is an AI-made overview: check details against the source.

- Interactive diagram: https://gitdiagram.com/nateshmbhat/flutter-multi-module-app
- Repository: https://github.com/nateshmbhat/flutter-multi-module-app

## Overview

1. This repository is a Flutter application, with a single Dart UI codebase deployed through the standard Flutter host layers for Android, iOS, and Web. The architecture is primarily “Flutter app + platform shells.”

2. The root `lib/main.dart` is the top-level Dart entrypoint for the app. It likely bootstraps the application and hands off to the shared app widget code in `lib/core`.

3. `lib/core` is a separate Dart package inside the repo, not just a folder. Its own `pubspec.yaml`, `lib/main.dart`, and `lib/my_app.dart` indicate a reusable app core layer that likely contains the main `MaterialApp`/app scaffold and shared UI setup.

4. `lib/onboarding` is another independent Dart package. Its separate `pubspec.yaml` and `lib/screens/my_screen/my_screen.dart` show a feature-oriented package dedicated to onboarding UI, rather than being mixed into the root app package.

5. The main in-repo architectural boundary is therefore between:
   - the root app entrypoint,
   - the shared/core app layer,
   - and the onboarding feature package.
   This suggests a modular Flutter structure, where feature code can be developed and tested somewhat independently.

6. The feature flow appears to center on onboarding screens. The presence of `lib/onboarding/lib/screens/my_screen/my_screen.dart` implies a screen-based UI module that is likely invoked from the core app shell during startup or navigation.

7. Platform-specific directories are standard Flutter host wrappers:
   - `android/` contains the Android launcher app and native entrypoint (`MainActivity.java`),
   - `ios/` contains the iOS runner (`AppDelegate.swift`, Xcode project, launch storyboard),
   - `web/` contains the static web bootstrap (`index.html`, `manifest.json`, icons).
   These layers are thin adapters around the Dart app rather than separate application logic.

8. The Android and iOS code appear to be mostly boilerplate shell code generated by Flutter. Their main job is to launch the Dart runtime, provide app icons/launch screens, and manage platform packaging.

9. The repo includes tests at multiple levels:
   - root `test/widget_test.dart`,
   - `lib/core/test/widget_test.dart`,
   - `lib/onboarding/test/widget_test.dart`.
   This indicates each package can be validated independently, which matches the modular package layout.

10. `analysis_options.yaml`, root `Makefile`, and the package-level `pubspec.yaml` files suggest the repo is organized with standard Flutter/Dart tooling and likely supports package-local development, analysis, and test execution. There is no sign of backend services, databases, or message brokers in the repository tree.

11. From an architecture-diagram perspective, the important picture is:
   Flutter framework runtime at the center, root app entrypoint on top of a shared core package, feature package(s) such as onboarding feeding UI screens into the app, and thin platform launchers on Android/iOS/Web around the edges.

12. In short, this is a modular Flutter frontend repo rather than a multi-service system. The meaningful boundaries are package boundaries inside `lib/`, with platform folders acting only as deployment targets.

Main entry points: [`lib/main.dart`](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/main.dart) (App entry), [`analysis_options.yaml`](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/analysis_options.yaml) (Tooling), [`lib/core/lib/main.dart`](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/core/lib/main.dart) (Core entry), [`lib/core/lib/my_app.dart`](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/core/lib/my_app.dart) (App shell)

## Diagram (Mermaid)

```mermaid
flowchart TD

subgraph group_app["Flutter app"]
  node_flutter_runtime(("Flutter runtime<br/>framework"))
  node_root_main["App entry<br/>dart entrypoint<br/>[main.dart]"]
end

subgraph group_core["Core package"]
  node_core_main["Core entry<br/>dart entrypoint<br/>[main.dart]"]
  node_core_app["App shell<br/>app scaffold<br/>[my_app.dart]"]
end

subgraph group_onboarding["Onboarding package"]
  node_onboarding_main["Onboarding entry<br/>dart entrypoint<br/>[main.dart]"]
  node_onboarding_screen["Onboarding screen<br/>feature screen<br/>[my_screen.dart]"]
end

subgraph group_platforms["Platform shells"]
  node_android_shell["Android app<br/>native host"]
  node_android_main_activity["MainActivity<br/>android entrypoint<br/>[MainActivity.java]"]
  node_ios_shell["iOS app<br/>native host"]
  node_ios_app_delegate["AppDelegate<br/>ios entrypoint<br/>[AppDelegate.swift]"]
  node_web_shell["Web app<br/>web host"]
end

subgraph group_tooling["Tooling"]
  node_root_test["Root test<br/>widget test<br/>[widget_test.dart]"]
  node_core_test["Core test<br/>widget test<br/>[widget_test.dart]"]
  node_onboarding_test["Onboarding test<br/>widget test<br/>[widget_test.dart]"]
  node_tooling_config["Tooling<br/>build config"]
end

node_flutter_runtime -->|"runs"| node_root_main
node_root_main -->|"delegates to"| node_core_main
node_core_main -->|"bootstraps"| node_core_app
node_core_app -->|"uses feature"| node_onboarding_main
node_onboarding_main -->|"opens"| node_onboarding_screen
node_android_shell -->|"contains"| node_android_main_activity
node_android_main_activity -->|"starts"| node_flutter_runtime
node_ios_shell -->|"contains"| node_ios_app_delegate
node_ios_app_delegate -->|"starts"| node_flutter_runtime
node_web_shell -->|"loads"| node_flutter_runtime
node_root_test -.->|"validates"| node_root_main
node_core_test -.->|"validates"| node_core_app
node_onboarding_test -.->|"validates"| node_onboarding_screen
node_tooling_config -.->|"analyzes"| node_root_main
node_tooling_config -.->|"analyzes"| node_core_main
node_tooling_config -.->|"analyzes"| node_onboarding_main

click node_root_main "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/main.dart"
click node_core_main "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/core/lib/main.dart"
click node_core_app "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/core/lib/my_app.dart"
click node_onboarding_main "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/onboarding/lib/main.dart"
click node_onboarding_screen "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/onboarding/lib/screens/my_screen/my_screen.dart"
click node_android_shell "https://github.com/nateshmbhat/flutter-multi-module-app/tree/master/android/app"
click node_android_main_activity "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/android/app/src/main/java/com/nuclei/falcon/MainActivity.java"
click node_ios_shell "https://github.com/nateshmbhat/flutter-multi-module-app/tree/master/ios/Runner"
click node_ios_app_delegate "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/ios/Runner/AppDelegate.swift"
click node_web_shell "https://github.com/nateshmbhat/flutter-multi-module-app/tree/master/web"
click node_root_test "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/test/widget_test.dart"
click node_core_test "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/core/test/widget_test.dart"
click node_onboarding_test "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/onboarding/test/widget_test.dart"
click node_tooling_config "https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/analysis_options.yaml"

classDef toneNeutral fill:#f8fafc,stroke:#334155,stroke-width:1.5px,color:#0f172a
classDef toneBlue fill:#dbeafe,stroke:#2563eb,stroke-width:1.5px,color:#172554
classDef toneAmber fill:#fef3c7,stroke:#d97706,stroke-width:1.5px,color:#78350f
classDef toneMint fill:#dcfce7,stroke:#16a34a,stroke-width:1.5px,color:#14532d
classDef toneRose fill:#ffe4e6,stroke:#e11d48,stroke-width:1.5px,color:#881337
classDef toneIndigo fill:#e0e7ff,stroke:#4f46e5,stroke-width:1.5px,color:#312e81
classDef toneTeal fill:#ccfbf1,stroke:#0f766e,stroke-width:1.5px,color:#134e4a
class node_flutter_runtime,node_root_main toneBlue
class node_core_main,node_core_app toneAmber
class node_onboarding_main,node_onboarding_screen toneMint
class node_android_shell,node_android_main_activity,node_ios_shell,node_ios_app_delegate,node_web_shell toneRose
class node_root_test,node_core_test,node_onboarding_test,node_tooling_config toneIndigo
```

## Components

### Flutter app

Root entrypoint and shared app flow

- **Flutter runtime**: framework · Shared Dart/Flutter execution environment
- [App entry](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/main.dart): dart entrypoint · Top-level app bootstrap in the root package · `lib/main.dart`

### Core package

Reusable shared app layer

- [Core entry](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/core/lib/main.dart): dart entrypoint · Package-local entrypoint for the shared core layer · `lib/core/lib/main.dart`
- [App shell](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/core/lib/my_app.dart): app scaffold · Shared application widget and UI wiring · `lib/core/lib/my_app.dart`

### Onboarding package

Feature module for onboarding UI

- [Onboarding entry](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/onboarding/lib/main.dart): dart entrypoint · Package-local entrypoint for the onboarding module · `lib/onboarding/lib/main.dart`
- [Onboarding screen](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/onboarding/lib/screens/my_screen/my_screen.dart): feature screen · Primary onboarding UI screen · `lib/onboarding/lib/screens/my_screen/my_screen.dart`

### Platform shells

Android, iOS, and web host layers

- [Android app](https://github.com/nateshmbhat/flutter-multi-module-app/tree/master/android/app): native host · Android launcher and packaging layer · `android/app`
- [MainActivity](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/android/app/src/main/java/com/nuclei/falcon/MainActivity.java): android entrypoint · Android host activity that boots Flutter · `android/app/src/main/java/com/nuclei/falcon/MainActivity.java`
- [iOS app](https://github.com/nateshmbhat/flutter-multi-module-app/tree/master/ios/Runner): native host · iOS runner and packaging layer · `ios/Runner`
- [AppDelegate](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/ios/Runner/AppDelegate.swift): ios entrypoint · iOS host application delegate · `ios/Runner/AppDelegate.swift`
- [Web app](https://github.com/nateshmbhat/flutter-multi-module-app/tree/master/web): web host · Static web bootstrap and assets · `web`

### Tooling

Build, analysis, and tests

- [Root test](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/test/widget_test.dart): widget test · Top-level widget test for the app package · `test/widget_test.dart`
- [Core test](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/core/test/widget_test.dart): widget test · Widget test for the core package · `lib/core/test/widget_test.dart`
- [Onboarding test](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/lib/onboarding/test/widget_test.dart): widget test · Widget test for the onboarding package · `lib/onboarding/test/widget_test.dart`
- [Tooling](https://github.com/nateshmbhat/flutter-multi-module-app/blob/master/analysis_options.yaml): build config · Repository-level analysis and build automation · `analysis_options.yaml`

## Connections

- Flutter runtime → App entry: runs · Flutter executes the root Dart entrypoint
- App entry → Core entry: delegates to · Root package hands off to the shared core layer
- Core entry → App shell: bootstraps · Core entrypoint builds the shared app shell
- App shell → Onboarding entry: uses feature · Shared app flow integrates the onboarding module
- Onboarding entry → Onboarding screen: opens · Onboarding entrypoint shows the primary screen
- Android app → MainActivity: contains · Android package contains the launcher activity
- MainActivity → Flutter runtime: starts · Android host starts the Flutter runtime
- iOS app → AppDelegate: contains · iOS package contains the application delegate
- AppDelegate → Flutter runtime: starts · iOS host starts the Flutter runtime
- Web app → Flutter runtime: loads · Web bootstrap loads the Flutter app
- Root test → App entry: validates · Top-level test exercises the root app
- Core test → App shell: validates · Core test exercises the shared app shell
- Onboarding test → Onboarding screen: validates · Onboarding test exercises the feature screen
- Tooling → App entry: analyzes · Repository tooling applies to the Dart app code
- Tooling → Core entry: analyzes · Repository tooling applies to the core package
- Tooling → Onboarding entry: analyzes · Repository tooling applies to the onboarding package