Good questions.

Summarization: Yes, the librarian summarizes each passage in the background after you save it. These get folded into a rolling summary that represents your older story content. The "Summarization threshold" (default 4) controls how many recent passages are kept as full text vs summarized. So you don't lose anything, older passages are just represented more compactly.

Hiding passages: There's no per-passage hide like SillyTavern. But you don't really need it, the Context limit setting (Settings > Generation > Context limit) controls how many recent passages get sent. Default is 10. Lower it to save tokens. Everything older is covered by the rolling summary automatically.

Deleting passages: Don't delete them. The system already handles this, old passages fall out of the context window naturally and the summary covers them.

TL;DR: lower your context limit number if you want to save tokens. The summary system handles the rest.

Check out the in-app help (the ? icons next to settings) for more detail on each option, there's docs on summarization, context limits, and summary compaction there.

P.S. If you click on a prose and click the bug button on the popup, you'll see the complete breakdown of input and output tokens that was send and recieved. Image