Monthly Budget

A simple personal finance app built with Flutter to track monthly incomes and expenses and quickly see your balance.

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Features

• Add monthly expenses and incomes
• Mark items as recurring (monthly) or one-time
• Tag items for categorization (e.g. "Home", "Work", "Subscriptions")
• Month selection with automatic filtering
• Automatic calculation of totals and balance per month
• Swipe to delete items
• Edit existing items
• Local persistence (data survives app restarts)
• Currency selection (EUR, USD, GBP, CHF)
• Toggle to show/hide tags on item cards
• Settings with tag management (rename/delete tags)
• Filter items by tags or recurring status
• Statistics with monthly breakdown by tag and recurring vs one-time charts

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Architecture Overview

• Global App State

  • Stored in a singleton AppState
  • Implemented using ChangeNotifier
  • Exposed via provider

• Business Logic

  • Lives inside AppState
  • UI never calculates totals directly

• UI

  • Pages are responsible for UI structure only
  • Reusable components live in widgets/
  • State is read using context.watch<AppState>()

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State Management Rules

• AppState is the single source of truth
• All mutations call notifyListeners()
• Widgets read state and trigger actions, but never contain business rules

Example:

context.read<AppState>().addExpense(item);

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Coding Conventions

Naming

• Files: snake_case.dart
• Classes: PascalCase
• Variables & methods: camelCase
• Widgets:
  • Pages → SomethingPage
  • Reusable widgets → descriptive nouns (BalanceCard, ItemList)

State

• Global state → AppState
• UI-only state → StatefulWidget
• No logic inside build() other than layout decisions

Models

• Immutable data classes
• No logic inside models
• Pure data containers