BaeckOnTrack 🥐

A minimal Flutter scanning app for delivery drivers to track bakery crates loaded into and removed from their vehicle.

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What it does

Drivers scan QR codes attached to bakery crates using the phone camera. Each scan is recorded as a Check In (loading a crate) or Check Out (removing a crate). The app shows a live count of crates currently in the vehicle.

Key design goal: maximum scanning speed with minimal UI interaction.

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Features

• Fullscreen camera scanner — continuous QR code detection via Google ML Kit
• Check In / Check Out mode — two large buttons to switch scanning direction
• Live inventory banner — shows total crate count and a breakdown by product type
• Scan feedback — short beep + vibration on every accepted scan
• Duplicate scan cooldown — 1-second cooldown per QR code prevents double-counting
• In-memory event log — full history of all scan events with timestamps

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Supported QR code formats

A plain numeric ID (most common):

14

Or a JSON payload:

{
  "package_id": "88291",
  "product_type": "croissant"
}

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Getting started

Prerequisites

• Flutter SDK ≥ 3.11
• Android device or emulator (API 21+)
• For Chrome emulation: any browser

Run on Android

flutter run

Run in Chrome (emulation mode)

flutter run -d chrome

In Chrome, tap the QR button (bottom right) to open the emulation dialog. Enter a crate ID (e.g. 14) and tap Scan to simulate a real scan.

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Project structure

lib/
├── main.dart                    # App entry point, Provider setup
├── models/
│   └── models.dart              # ScanMode, InventoryItem, ScanEvent
├── providers/
│   └── inventory_provider.dart  # In-memory state, scan logic, cooldown
├── screens/
│   └── scanner_screen.dart      # Main screen (camera + overlays)
├── services/
│   └── feedback_service.dart    # Beep generation + vibration
└── widgets/
    ├── inventory_banner.dart    # Top floating crate count banner
    └── mode_toggle.dart         # Check In / Check Out buttons

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Dependencies

Package	Purpose
mobile_scanner	QR code detection via camera
provider	Lightweight state management
vibration	Haptic feedback on scan
audioplayers	Beep audio playback

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Architecture

State is managed with a single InventoryProvider (ChangeNotifier). The inventory is an in-memory Map<String, InventoryItem> keyed by package_id. All scan events are appended to a List<ScanEvent> for audit/export purposes.

The beep is generated programmatically as a PCM WAV sine wave — no audio asset files are required.