Reading Tree keeps the original words in place. Every node links to the passage it covers, and every paragraph links back to the node that explains its role. Nodes are weighted by importance so you can see at a glance which parts carry the most weight.
Demo (desktop only): https://modelvoyager.github.io/ReadingTree/on-liberty-ch1-re...
GitHub: https://github.com/ModelVoyager/ReadingTree
It's an agent skill (a set of instructions and templates you upload to an AI chat) that works with Claude and ChatGPT. Only tested with Claude Opus 4.6 (extended thinking) and GPT-5.4 Thinking. Other models may not produce usable results. Free and open source. I designed the interaction model and UX, then used AI to build it out. Most of the effort went into actually reading with it and fixing what didn't work.
I've been the only user for a few weeks. If you read things where the argument structure matters and summaries feel like they lose too much, I'd like to hear whether this helps.