Suggestion: On the "Filter List" menu, there's already a checkbox to filter for books that are part of (any) challenge. Add an option to select a specific challenge or challenges. (It would be cool if it's similar to the genres or tags search, where instead of a checkbox there are include/exclude boxes to search the names of your active challenges.)

Goal: Find a book that fits your current reading vibes that's part of a specific open challenge that you're participating in.

Example: I created and joined a number-type challenge to work through a specific TBR pile of 111 books that can be read in any order and are all different kinds of genres and moods. I want the next book I choose to be one of the books that's part of that specific challenge, but also to fit what I'm in the mood for at the time without having to read through every title in the list. https://app.thestorygraph.com/reading_challenges/fb7834ee-9633-4e53-8aae-166e2d0d3b4e

ORIGINAL SUGGESTION

Idea #1: Add a filter to challenge pages so you can filter within the list of books you've (or anyone has?) added to that specific challenge. This is especially helpful for number type challenges, where there can be a big pile of books without a prompt associated.

Idea #2: Add a "challenges" option to the filter settings on your To Read list that lets you select challenges you've joined. It can then search for books that meet your other criteria AND are in a specific challenge.

Or something else that someone else comes up with to reach the stated outcome?