Deck comment mentions do not trigger notifications (users vs user)

[sowo-dev]

Describe the bug

Mentions in Deck card comments are parsed correctly, but no notification is created for the mentioned user.

Deck 1.18.4 checks in NotificationHelper::sendMention():

if (($mention['type'] ?? 'users') !== 'users') {
    continue;
}

However, Nextcloud returns the mention type user, not users, so normal user mentions are skipped.

To Reproduce

1. Create a Deck board and share it with another user, e.g. testuser.
2. Create a card.
3. Add a comment containing @testuser mention test.
4. Log in as testuser.
5. No notification is shown.

The comment API correctly recognizes the mention:

"mentions": [
    {
        "mentionId": "testuser",
        "mentionType": "user",
        "mentionDisplayName": "Test User"
    }
]

Other notifications work correctly:

• sharing a Deck board
• assigning/sharing a Deck card
• mentioning the same user in a regular Nextcloud file comment

Expected behavior

The mentioned user should receive a Nextcloud notification.

Screenshots

Not applicable.

Client details:

• Device: desktop
• Browser: not relevant; reproducible server-side

Server details

Operating system: Ubuntu

Nextcloud version: 34.0.3

Deck version: 1.18.4

Signing status:

No errors before applying the workaround (occ integrity:check-app deck produced no output).

Additional information

Changing

if (($mention['type'] ?? 'users') !== 'users') {

to

if (($mention['type'] ?? null) !== 'user') {

immediately restores Deck mention notifications.

This may have been introduced with the board-access check for mentioned users in PR #7983.

Logs

No relevant errors observed.