I‘m building Sticker, a simple note-taking app for Mac that lets you add markdown based notes to applications, files and other windows. The note is only shown when the connected file, window or app is selected / has focus. Currently, I use it myself to add notes to specific files and projects, e.g. adding a note to my tax folder for 2025 instead of creating a txt file or adding a ToDo to a specific workspace when opened in VS Code. The notes are completely file/markdown based and can be simply synced with other devices. This way, it’s also possible to edit the note outside of Sticker.