Mood Diary is an offline-first daily journaling app that combines mood tracking with weather logging, visualized through a dynamic gradient sky background. Core Features: Mood Tracking — 7 Levels: Bliss, Happy, Calm, Neutral, Tired, Sad, Angry. Each mood maps to a distinct color used to tint the dynamic background. Weather Logging — 7 Types: Sunny, Cloudy, Rain, Thunder, Snow, Fog, Wind. Combined with mood color to create a unique sky gradient per entry. Daily Entry System: One entry per day (upsert model). Supports optional free-text notes. Edit or delete any past entry from History view. Streak Tracking: Counts consecutive journaling days. Displayed on the home screen to reinforce the daily habit. Stats View: Weekly mood score chart and mood distribution breakdown. Calculated from stored entries. Persistence: FileManager + JSON-based local storage. No Core Data, no iCloud, no network access. All data lives on-device. Bilingual UI: Full English and Simplified Chinese localization with locale-aware date formatting. No ads, no account, no data collection.