Implements a volume booster using Android's LoudnessEnhancer with a periodic reset workaround to prevent audio drift on certain devices. Demonstrates deep understanding of Android audio framework internals and provides a self-contained utility that can be extracted for any app needing audio gain beyond system limits.

Provides folder zipping with pattern-based file filtering and explicit zip-slip protection. The implementation is clean, parameterized, and handles edge cases like empty directories. Can be reused in any Android project requiring secure backup/restore functionality.

A custom Android view that detects double-tap gestures on a video player and provides seek-forward/seek-backward actions with visual feedback. The implementation is self-contained, uses Kotlin coroutines for debouncing, and includes a YouTube-style overlay. Easily extractable for any video player app needing double-tap seek.

Manages subtitle display by wrapping ExoPlayer's SubtitleView, applying system caption styles, and normalizing VTT/TTML cue text to avoid duplicate lines. Handles API level differences and provides a clean interface for subtitle styling. Reusable in any ExoPlayer-based app needing advanced subtitle control.

Persists UI state (header index, video position) across app crashes using SharedPreferences. Implements a simple but effective crash recovery mechanism that restores the last browsing position. The pattern is generic and can be adapted for any Android app needing crash-resilient navigation state.