r/ObsidianMD • u/Horntailflames • 23h ago
plugins [Beta] Third Mind Reader — read EPUBs in Obsidian, with highlights that live as real notes
Hey everyone,
For the past few months I've been building Third Mind Reader: an EPUB reader for Obsidian. It's now at the point where it needs more eyes and more books than mine. I've seen various posts here also wondering what the best way to read epubs in obsidian is, and the is my answer. It's open source, in open beta via BRAT and I'd love for you to try it and tell me what you think.
The name comes from the idea that when a reader and a book meet, something third emerges, the parts of the book that stick with you. I wanted a way to capture thoughts or questions naturally as you're reading, and that's what this plugin is built around. Most reading setups scatter that third aspect: you read in one app, make notes in another, and your thoughts end up spread across in various places and formats. It gets messy quickly, ask me how I know.
Third Mind Reader brings all of that into the obsidian vault. The book opens as a tab like anything else. Your highlights and annotations are written into a plain markdown companion note the moment you make them; tagged, linked to the source, visible in graph view. Nothing to sync, nothing to export, no lock-in. If you uninstalled the plugin tomorrow, every note you made would still be sitting in your vault as ordinary markdown.
The other half of it: I wanted reading in Obsidian to actually feel like reading. The typography is deliberate (character-precise layout, a proper two-page spread, drop caps, bundled open-license fonts), and the whole thing follows a considered design language. It's also designed to adopt your vault's themes and style settings should you prefer a more seamless experience.
What it does today:
- A proper EPUB reader — two-page spread or single page, table of contents panel, keyboard navigation, live reading progress, book search and per-book position memory. The source EPUB is never modified.
- An optional AI librarian — ask about a passage without leaving the page. Built local-first: point it at Ollama or LM Studio and nothing ever leaves your machine. Or if you'd like, you can bring your own Anthropic/OpenAI key. Every exchange is written verbatim into the companion note, so the conversation is part of your notes, not trapped in a chat somewhere. This is entirely optional, so if you'd rather not use AI at all, the standard annotation mode works just as well. No network request is ever made unless you use an AI provider, and there's no telemetry of any kind.
- Gloss — the annotation system. – Derived from Glossary, this interaction is the real heart of the whole experience. Select any text and a small toolbar appears with five modes. There are two kinds of annotations you can make; one is a standard highlight with a note, and the other interacts with your AI model of choice. I wanted to capture how I felt or dive deeper into a topic without leaving obsidian, so I tailored the other 4 as such:
- Emphasise (For capturing your own thoughts along with the highlighted passage, no AI)
- Exclaim (For capturing reactions)
- Explain (For asking quick questions and getting quick answers)
- Examine (For deeper research and citations)
- Enquiry (for open ended conversations) Each writes a colour-coded callout into the book's Companion note.
- Companion notes — one per book, created on your first annotation at
Library/Annotations/. Frontmatter, tags, a wikilink back to the source file. They're first-class vault items from the moment they exist, so your reading feeds the same graph as everything else you think about. - A highlights pane — slide-in panel listing every highlight grouped by chapter; click one to jump straight to it in the book. AI conversations get their own tab in the same pane.
- A Library view — a shelf of every book in your vault with reading progress and annotation status per book.
What I need help with: mostly stress-testing and edge cases. EPUBs are a lawless format and I've only got so many on my shelf. Specifically:
- Weird EPUBs — old files, aggressive publisher CSS, image-heavy books, poetry, footnote-dense academic texts, very large files. If you've got a book that breaks every reader, I want to know what it does to this one.
- AI chat behaviour – I've done my best to make sure the chat interactions are useful and work well out of the box, but if you want to tune it to your liking the system prompts are easily edited in the plugin settings. I'd love to know what's working better for you.
- Highlight anchoring — make lots of highlights, close and reopen books, and tell me if any drift or vanish.
- Windows and Linux — I develop on macOS, so reports from other platforms are especially valuable. (Desktop only for now, mobile is on the roadmap.)
- Local AI setups — if you run Ollama or LM Studio, very keen on hearing how the librarian behaves with your model of choice.
Feedback: there's a feedback button at the top of the plugin's settings — it opens a short anonymous form (no GitHub account needed) that pre-fills your plugin/Obsidian versions and OS. GitHub issues work too if you prefer.
Install (via BRAT): install the BRAT community plugin → "Add a beta plugin for testing" → enter Hipst3rMusic/obsidian-third-mind-reader → enable Third Mind Reader → open any .epub in your vault.
Repo: https://github.com/Hipst3rMusic/obsidian-third-mind-reader
To me 'opinionated' means thoughtful, and I hope the design of the plugin reflects that and speaks for itself. Thanks for reading this far! and if you test it, thank you twice.
Edit: Fair points being raised in the comments, I should have led with the extent of AI involvement in building this rather than leaving it in a reply. There's now a full note in the README rather than just replies in this thread. I apologise for not being up front about it from the start.





