x (A) stay conform to todo.txt format
(A) syntax highlighting (colors) https://code.visualstudio.com/api/language-extensions/overview#declarative-language-features vs code documentation tells us that this is done best by using TextMate grammars https://code.visualstudio.com/api/language-extensions/syntax-highlight-guide#textmate-grammars never the less the most popular todotxt extensions use regExp to do the decorations, for example https://github.com/robarnolddev/todo-txt/blob/master/src/decorators/ToDoDecorator.ts
(A) cursor-sensitive auto completion https://code.visualstudio.com/api/language-extensions/overview#declarative-language-features (A) publishing with Comsysto profile https://code.visualstudio.com/api/working-with-extensions/publishing-extension (A) auto-sort by priority (A) auto-timestamp (creation date, completion date) (A) toggle hide done (B) show done items in secondary section (below todo items) (B) integration tests https://code.visualstudio.com/api/working-with-extensions/testing-extension (B) project and context definitions and links that let you cmd-click to the definition https://code.visualstudio.com/api/language-extensions/overview#programmatic-language-features (B) sort by due date