@room pills don't render correctly when sent using Markdown input

[frebib]

Steps to reproduce

1. Use the non-RTE input field and send an @room mention
2. Note that the event doesn't send a formatted body, nor does the message bubble render the @room as a pill

Outcome

What did you expect?

@room to render as a pill

What happened instead?

It rendered as plain text

Your phone model

No response

Operating system version

No response

Application version and app store

No response

Homeserver

No response

Will you send logs?

No

Are you willing to provide a PR?

No

[bmarty]

Without formating, this event is sent:

  "content": {
    "body": "@room Test",
    "m.mentions": {
      "room": true
    },
    "msgtype": "m.text"
  },

and with formatting:

  "content": {
    "body": "@room test 2",
    "format": "org.matrix.custom.html",
    "formatted_body": "@room test 2",
    "m.mentions": {},
    "msgtype": "m.text"
  },

and this is how this render on Web:

and on EXA this is the opposite:

Also this line is crashing in debug build, since mentionSpan.rawValue is equal to @room and this is not a valid userId.

We have several problems to fix, not only a rendering problem.

[frebib]

Intentional mentions are working now, but the markdown input is still not sending a formatted body, so the room pill still doesn't render as a pill. EW does render a pill even without a formatted_body though. Not sure what the intention is here

  "content": {
    "msgtype": "m.text",
    "body": "@room ",
    "m.mentions": {
      "room": true
    }
  },

[jmartinesp]

Intentional mentions are working now, but the markdown input is still not sending a formatted body, so the room pill still doesn't render as a pill.

Oh, true. I did all my tests with messages with both an @room mention and a explicit one so they were always formatted and I never found this issue. Let me check if I can fix this remaining case.

[jmartinesp]

This should now be fixed with #3201.