Read only challenges functionality

Currently all users have an access to the challenge, if it is discoverable.
If the challenge is not discoverable, users can access that using an url shared by admin.

Community members are wondering if there is possibility to create an option when challenge is in 'read only' mode, so they can review the tasks available in a challenge and accept that from their end without possibility of doing any edits within the task when this mode is 'on'.

As we know that our source material is good and correct leads/tasks are being shared within a challenge, community members would like to review and accept that. After the green light is given, this 'lock' could be released and people might contribute to this or another challenge - currently mode with a challenge not discoverable and available for community members is not sufficient for them, as other community members who got the link within organized editing notification may access that and edit the database from the very beginning.

Were there thoughts and ideas about this kind of solution being implemented in MapRoulette? What amount of work is required to create this kind of functionality?

Thanks in advance for your feedback!

The issue names no files, tests, or entry points. Start by tracing how challenge discoverability and shared-URL access are handled in the frontend, then define the read-only state, its permissions, and how it is released; done means users can review and accept tasks without editing while the mode is enabled.