In the past I'd recommended Trilium Notes as a good FLOSS alternative to Obsidian for a note taking database app, but unfortunately today after failing to restore a trilium backup file to a new install, and finding that the documentation on backups isn't accurate (as in, there are not buttons in the app that the documentation claims are there, and nothing I have tried has worked to restore the backup), I discovered on the github a Claude.md in the repository, and the commit history shows that in the past few months Claude has become one of the most prolific contributors on the project.
If anyone is using this app based on my previous recommendation, I'd personally suggest migrating to a different note-taking app that isn't vibe-coded (and exports backups to plain text, instead of some database format), perhaps CherryTree?
Unfortunately Logseq also has a claude section in their github, so they are using LLM's too, though I do not know to what extent (the cloude bot has few direct commits, but the devs could be using it for their own pull requests).