Implements a fixed-size memory arena allocator (MemoryArena<T>) for efficient allocation of many small objects. Used internally for Markdown AST nodes, this component could be extracted into any project that requires high-performance, low-fragmentation allocation of homogeneous objects. Demonstrates a non-obvious skill in custom memory management within a Qt application.

Provides an AsyncTextWriter that writes text to a file on a background thread using QtConcurrent::run, emitting writeComplete or writeError signals upon completion. This component is self-contained (depends only on Qt) and can be reused in any Qt application needing non-blocking file writes with progress/error reporting. Encapsulates the threading and encoding logic cleanly.

Implements color scheme generation algorithms including luminance calculation (per WCAG), contrast ratio computation, color mixing, and adaptive shading. Used to derive editor and preview color schemes from a base theme color. This is a standalone utility class that could be extracted into any application needing dynamic color palette generation with accessibility-awareness (e.g., ensuring sufficient contrast).

A SpellCheckDecorator that attaches to a QPlainTextEdit and adds real-time spell-check underlining using KDE Sonnet, without interfering with the syntax highlighter. It delegates to the Sonnet spell checker and provides context menu corrections. This decorator pattern is reusable in any Qt text editor that wants to add spell checking as a separate, non-intrusive layer.

A self-contained FindReplace widget implementing find, replace, replace-all, regex support, match case, whole word, highlight matches, and search history persistence via QSettings. It is designed as a reusable QWidget that can be embedded in any QPlainTextEdit-based editor. Demonstrates clean state management and user experience patterns (e.g., auto-focus, incremental search timer).