Habit Streak Daily

HabitStreak implements evidence-based habit-tracking principles with a clean SwiftUI interface designed for iOS 16 and above.

CORE MECHANICS
• Streak Engine: calculates current streak by walking back consecutive completed days from today; resets on any missed day
• Best Streak: all-time record of the longest unbroken consecutive sequence per habit
• Completion Rate: 7-day and 30-day rolling window ratios displayed per habit and aggregated

HABIT CONFIGURATION
| Parameter   | Options                          |
|-------------|----------------------------------|
| Frequency   | Daily / Weekdays / Weekly        |
| Icon        | 10 SF Symbols (drop, book, flame…)|
| Color       | 7 preset hex colors               |
| Name        | Free-text, any length            |

STATISTICS MODULE
• Overview dashboard: total habit count, today's completions, 7-day aggregate success rate
• Per-habit detail: current streak, best streak, 14-day tile visualization, 30-day completion count

DATA LAYER
• Persistence: UserDefaults with JSON encoding (Codable structs)
• No network calls — fully offline
• No account, no analytics, no third-party SDKs

INTERFACE
• SwiftUI-native, supports Dynamic Type
• System-aware Light/Dark theme
• Localized in English and Simplified Chinese
• Tab navigation: Habits / Stats / Settings

PRIVACY
Zero data leaves the device. Deletion of the app permanently removes all habit data.