Zen Kana - Learn Japanese

Practice experience - Added dynamic practice expansion after mastery, offering up to five new kana or vocabulary items at a time. - Added progression through kana rows and JLPT vocabulary chunks. - Added “Today’s Practice” selection restoration, preserving newly expanded items when configured. - Added expansion banners, continuation actions, and “practice again / choose more items” flows. - Improved answer normalization, alternate answers, parenthetical answers, kanji display, romaji display, and stable item serialization. - Removed the old practice session-limit and adaptive-difficulty implementation. - Improved minimum session sizing and smart-banner behavior. Selection and progress UI - Improved the practice growth journey in selection screens and session summaries. - Added clearer progression through kana and JLPT content. - Improved selected-item practice actions and expansion choices. - Refined JLPT and kana level layouts, including mobile behavior. - Added reusable section headers, selectable chunk cards, and shared decoration helpers. - Simplified and consolidated repeated selection and item-resolution logic. - Improved lazy list usage and reduced unnecessary widget rebuilds. Data, sync, and security - Hardened local/cloud deserialization against malformed or incorrectly typed data. - Fixed cross-account contamination risks when switching users on a shared device. - Bound delayed uploads to the account that scheduled them. - Debounced cloud settings/statistics writes while flushing pending writes on lifecycle changes. - Added safer sync merging for lists, statistics, settings, and spaced-repetition data. - Improved consent data validation and handling. Performance and platform work - Reduced rebuilds using Selector, ValueListenableBuilder, and more focused state subscriptions. - Improved spaced-repetition lookups and item resolution. - Parallelized Firebase, accessibility, and learning-content initialization during startup.