Lower-priority issues with things that don't work as well as they could when running in a degraded "Read Only" mode:

Important

• ApplicationSearch relies on doing writes. Can we just send users to a big messy GET-parameter URL instead?
• Login won't work since it can't write new sessions. T4571 has some ideas about issuing read-only-mode-only sessions which are pure hash magic.

Less Important

• DarkConsole doesn't work at all, and doesn't tell you that it won't work. Should probably just be replaced with "this doesn't work in read-only mode", at least for the foreseeable future.
• You won't be able to mark notifications as read, since that's a write. Maybe this should have a hint in the notification menu, since it's annoying/confusing? Maybe it just doesn't matter too much.
• Session cycling probably won't work (?). This is unlikely to affect anyone during brief downtime, but could become an issue if an install is being archived.
• Comments and editing UIs should be disabled in the UI where reasonable.
• Daemon console does a write-mode read to get more accurate data. Maybe we should add an "write, unless read-only, then read" mode for this? We probably only have a few of them.
• Does Conpherence try to do mark-as-read writes for unread messages?
• You can't log out, but we could give you a degraded version (clear cookies without nuking the session) after warning you that it would be less effective than usual.
• Read-only Conduit methods, like conduit.ping, reportedly do not work, presumably because they're doing a log write.