feat: complete app integration and final merge to main repo

leaderboard_app/.gitignore

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+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.build/
+.buildlog/
+.history
+.svn/
+.swiftpm/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+**/ios/Flutter/.last_build_id
+.dart_tool/
+.flutter-plugins-dependencies
+.pub-cache/
+.pub/
+/build/
+/coverage/
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json
+
+# Android Studio will place build artifacts here
+/android/app/debug
+/android/app/profile
+/android/app/release

leaderboard_app/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: "02da4cc00db9eb97fc48e89d319ef48518c2440a"
+  channel: "master"
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+      base_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+    - platform: android
+      create_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+      base_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+    - platform: ios
+      create_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+      base_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+    - platform: linux
+      create_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+      base_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+    - platform: macos
+      create_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+      base_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+    - platform: web
+      create_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+      base_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+    - platform: windows
+      create_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+      base_revision: 02da4cc00db9eb97fc48e89d319ef48518c2440a
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'

leaderboard_app/README.md

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+# leaderboard_app
+
+Flutter application with backend integration using `dio` + `retrofit` for typed HTTP APIs.
+
+## Backend Integration
+
+We use:
+
+* `dio` for HTTP transport, interceptors, timeouts.
+* `retrofit` for declarative REST interface generation (`lib/services/core/rest_client.dart`).
+* `build_runner` + `retrofit_generator` (and `json_serializable` if/when model code generation is added).
+
+### Generating code
+
+Run code generation after updating API interface annotations:
+
+```bash
+dart run build_runner build --delete-conflicting-outputs
+```
+
+### Using the REST client
+
+```dart
+import 'package:leaderboard_app/services/core/dio_provider.dart';
+import 'package:leaderboard_app/services/core/rest_client.dart';
+
+final dio = await DioProvider.getInstance();
+final api = RestClient(dio);
+
+final start = await api.startVerification({'leetcodeUsername': 'someUser'});
+final status = await api.getVerificationStatus('someUser');
+```
+
+Auth tokens (JWT) are automatically attached from `SharedPreferences` via an interceptor in `DioProvider`.
+
+### Environment / Base URL
+
+Centralized in `lib/config/api_config.dart`.
+
+Default baked-in base URL (when no override is supplied):
+
+```
+http://140.238.213.170:3002/api
+```
+
+Override at build/run time:
+
+```bash
+flutter run --dart-define=API_BASE_URL=https://your.api.host/api
+```
+
+Release / CI example:
+
+```bash
+flutter build apk --dart-define=API_BASE_URL=https://prod.api.host/api
+```
+
+Trailing slashes are trimmed automatically. Keep `/api` if your backend routes are under that prefix.
+
+### Adding new endpoints
+
+1. Edit `lib/services/core/rest_client.dart` – add a method with appropriate HTTP verb annotation.
+2. Run the build command above to regenerate `rest_client.g.dart`.
+3. Consume the new method from services or providers.
+
+### Logging & Retry
+
+`DioProvider` adds a lightweight log interceptor and simple retry (only once) for idempotent GET requests on connection errors.
+
+---
+
+Generated code (`rest_client.g.dart`) should not be manually edited.
+
+
+## Building a Release APK / Sharing the App
+
+1. (Optional) Override the API base URL at build time (recommended for different envs):
+
+```bash
+flutter build apk --release --dart-define=API_BASE_URL=https://prod.api.host/api
+```
+
+If you omit `--dart-define` the baked-in default from `ApiConfig` is used.
+
+2. The unsigned release APK will be at:
+
+```
+build\app\outputs\flutter-apk\app-release.apk
+```
+
+3. (Recommended) Create a keystore and configure signing in `android/key.properties` + `build.gradle` to avoid Play Store rejection and to allow in-place upgrades.
+
+### Example keystore creation (run once)
+
+```bash
+keytool -genkey -v -keystore my-release-key.keystore -alias upload -keyalg RSA -keysize 2048 -validity 10000
+```
+
+Place the keystore under `android/` (never commit to VCS) and add a `key.properties`:
+
+```
+storePassword=YOUR_STORE_PASSWORD
+keyPassword=YOUR_KEY_PASSWORD
+keyAlias=upload
+storeFile=../my-release-key.keystore
+```
+
+Then update `android/app/build.gradle` signingConfigs + buildTypes (if not already present).
+
+### Distributing for quick tests
+
+You can directly share `app-release.apk` with testers (they must enable install from unknown sources). For Play Store publishing prefer an AAB:
+
+```bash
+flutter build appbundle --dart-define=API_BASE_URL=https://prod.api.host/api
+```
+
+## Troubleshooting: "Cannot reach server. Check BASE_URL..."
+
+This message originates from `ErrorUtils.fromDio` when the `DioExceptionType.connectionError` occurs. Common causes:
+
+| Cause | Fix |
+|-------|-----|
+| Device has no internet | Ensure Wi‑Fi/data works (open a website) |
+| Backend URL wrong or down | Open the URL in mobile Chrome to verify response |
+| Using `localhost` / private IP not reachable externally | Use a public/stable host or expose via tunneling (ngrok, Cloudflare) |
+| HTTP blocked (if you switch to HTTPS only) | Ensure correct scheme in `API_BASE_URL` |
+| Missing INTERNET permission | Manifest now includes `<uses-permission android:name="android.permission.INTERNET" />` |
+
+To quickly verify the URL the app is using, add a temporary log:
+
+```dart
+print('API base URL: ' + ApiConfig.baseUrl);
+```
+
+Or run with an override:
+
+```bash
+flutter run --release --dart-define=API_BASE_URL=https://your-temp-api/api
+```
+
+If the backend uses a self-signed certificate, Android may reject it—use a valid cert (Let's Encrypt) for production.
+
+## Future Enhancements (Optional)
+
+* Add build flavors: dev / staging / prod with per-flavor `--dart-define` presets.
+* Add environment banner in-app for non-prod.
+* Implement exponential backoff retries for transient network errors.
+* Add Sentry or similar for error monitoring.
+
+## Splash Screen & Offline Handling
+
+The app shows a native splash (configured via `flutter_native_splash`) while core services initialize. For returning users (flag stored in `SharedPreferences` as `returningUser`), dashboard data is preloaded (daily question, submissions if verified, leaderboard) before removing the splash to deliver a populated home view quickly.
+
+If there's no network connectivity at launch, a dedicated offline screen (`NoInternetPage`) is displayed. Connectivity is monitored with `connectivity_plus` through `ConnectivityProvider`; once a connection becomes available the app automatically proceeds with initialization and dismisses the splash.
+
+Update splash assets/colors in `pubspec.yaml` under `flutter_native_splash:` then regenerate:
+
+```bash
+flutter pub run flutter_native_splash:create
+```
+
+Key files:
+
+* `lib/main.dart` – splash preservation & initialization logic (`_AppInitializer`).
+* `lib/provider/connectivity_provider.dart` – connectivity listener.
+* `lib/pages/no_internet_page.dart` – offline UI.
+
+To disable preloading behavior simply remove the `dashboardProvider.loadAll()` call in `_preload()`.
+

leaderboard_app/analysis_options.yaml

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+include: package:flutter_lints/flutter.yaml

leaderboard_app/android/.gitignore

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+gradle-wrapper.jar
+/.gradle
+/captures/
+/gradlew
+/gradlew.bat
+/local.properties
+GeneratedPluginRegistrant.java
+.cxx/
+
+# Remember to never publicly share your keystore.
+# See https://flutter.dev/to/reference-keystore
+key.properties
+**/*.keystore
+**/*.jks

leaderboard_app/android/app/build.gradle.kts

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+plugins {
+    id("com.android.application")
+    id("kotlin-android")
+    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
+    id("dev.flutter.flutter-gradle-plugin")
+}
+
+android {
+    namespace = "com.dscvit.leeterboard"
+    compileSdk = flutter.compileSdkVersion
+    ndkVersion = flutter.ndkVersion
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_11
+    }
+
+    kotlinOptions {
+        jvmTarget = JavaVersion.VERSION_11.toString()
+    }
+
+    defaultConfig {
+        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
+        applicationId = "com.dscvit.leeterboard"
+        // You can update the following values to match your application needs.
+        // For more information, see: https://flutter.dev/to/review-gradle-config.
+        minSdk = flutter.minSdkVersion
+        targetSdk = flutter.targetSdkVersion
+        versionCode = flutter.versionCode
+        versionName = flutter.versionName
+    }
+
+    buildTypes {
+        release {
+            // TODO: Add your own signing config for the release build.
+            // Signing with the debug keys for now, so `flutter run --release` works.
+            signingConfig = signingConfigs.getByName("debug")
+        }
+    }
+}
+
+flutter {
+    source = "../.."
+}

leaderboard_app/android/app/src/debug/AndroidManifest.xml

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+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- The INTERNET permission is required for development. Specifically,
+         the Flutter tool needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>

leaderboard_app/android/app/src/main/AndroidManifest.xml

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+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- Network permissions required for API calls in release builds -->
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <application
+        android:label="LeeterBoard"
+        android:name="${applicationName}"
+        android:icon="@mipmap/ic_launcher"
+        android:usesCleartextTraffic="true"
+        android:networkSecurityConfig="@xml/network_security_config">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true"
+            android:launchMode="singleTop"
+            android:taskAffinity=""
+            android:theme="@style/LaunchTheme"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:hardwareAccelerated="true"
+            android:windowSoftInputMode="adjustResize">
+            <!-- Specifies an Android theme to apply to this Activity as soon as
+                 the Android process has started. This theme is visible to the user
+                 while the Flutter UI initializes. After that, this theme continues
+                 to determine the Window background behind the Flutter UI. -->
+            <meta-data
+              android:name="io.flutter.embedding.android.NormalTheme"
+              android:resource="@style/NormalTheme"
+              />
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+        <!-- Don't delete the meta-data below.
+             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
+        <meta-data
+            android:name="flutterEmbedding"
+            android:value="2" />
+    </application>
+    <!-- Required to query activities that can process text, see:
+         https://developer.android.com/training/package-visibility and
+         https://developer.android.com/reference/android/content/Intent#ACTION_PROCESS_TEXT.
+
+         In particular, this is used by the Flutter engine in io.flutter.plugin.text.ProcessTextPlugin. -->
+    <queries>
+        <intent>
+            <action android:name="android.intent.action.PROCESS_TEXT"/>
+            <data android:mimeType="text/plain"/>
+        </intent>
+    </queries>
+</manifest>

leaderboard_app/android/app/src/main/kotlin/com/example/leaderboard_app/MainActivity.kt

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+package com.dscvit.leeterboard
+
+import io.flutter.embedding.android.FlutterActivity
+
+class MainActivity : FlutterActivity()

leaderboard_app/android/app/src/main/res/drawable-v21/launch_background.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <bitmap android:gravity="fill" android:src="@drawable/background"/>
+    </item>
+    <item>
+        <bitmap android:gravity="center" android:src="@drawable/splash"/>
+    </item>
+</layer-list>