Case-insensitive topics in unreads data

[gnprice]

Topic names in Zulip are case-insensitive.

Currently, however, our Unreads data structure keeps the data for each channel/stream as just a Map keyed by topic name. It should instead treat messages where the topic names differ only in case (and that have the same stream ID) as belonging to the same topic.

There's actually a server bug where this doesn't properly happen in the unreads data we get in the initial snapshot:
https://chat.zulip.org/#narrow/stream/48-mobile/topic/Case.20sensitivity.20in.20topics/near/1954334
But we should also handle this properly in events, and in looking up data. For example handleMessageEvent should put the new message into an existing topic if it differs only in case.

If fixing this issue for events has a side effect of working around the server-side issue, then that's nice. But if it doesn't, we don't need to add a workaround. The issue seems fairly uncommon, so it's OK if the symptoms continue when using a server that still has the bug.

Related issues

• Extra recipient header when topic changes case #739
• android: Notification grouping should treat topics case-insensitively #1205

[Adityakk9031]

i am going to work on this issue

[chrisbobbe]

Please take a look at the Zulip project's guide to getting involved with the code:

https://zulip.readthedocs.io/en/latest/contributing/contributing.html#your-first-codebase-contribution
https://zulip.readthedocs.io/en/latest/contributing/contributing.html#picking-an-issue-to-work-on

[Adityakk9031]

ok