fix: Register default file action to prevent download instead of open

[timar]

The Viewer app's 'view' file action checks window.OCA.Viewer.mimetypes to decide if it can handle a file. However, those mimetypes are only populated on DOMContentLoaded when handlers are bridged from the @nextcloud/viewer npm package to the ViewerService. If the Files app renders the file list before that event fires, the 'view' action's enabled() returns false and the 'download' action (order 30) becomes the default — causing document files to be downloaded instead of opened in Collabora Online.

Register a richdocuments-specific default file action that checks against the OCS capability mimetype list (baked into the page HTML via initial state, always available immediately) instead of the ViewerService's runtime mimetypes. When the Viewer's 'view' action works correctly both actions are enabled but 'view' wins (registered first). When 'view' is disabled due to the timing race, the new action takes over. Execution delegates to the Viewer's own 'view' action for proper URL history and prev/next navigation support.

[juliusknorr]

This approach seems more like a workaround. Can you tell how you replicated this and if it was specific to a nextcloud version? Last week #5355 was raised as we missed that backport for 32 it seemed. #4983 was the pr for master and is supposed to fix exactly the issue you mentioned.

[timar]

This approach seems more like a workaround. Can you tell how you replicated this and if it was specific to a nextcloud version? Last week #5355 was raised as we missed that backport for 32 it seemed. #4983 was the pr for master and is supposed to fix exactly the issue you mentioned.

Yes, it's sort of a hack. I tried to fix the underlying timing issue in viewer, but I failed. I'm happy if you fixed it properly in a different way. We always had this issue with different versions, but I debugged and tested my fix with Nextcloud 33.0.0 RC4 and richdocuments 10.0.0-beta.1.
It's not 100% reproducible, sometimes when you load the Files view, the click on files download them instead of opening in COOL. The bug disappears, if we enter a subdirectory. It also disappears, if we reload the page 1-4 times. And sometimes file opening works immediately.
With this hack I submitted, the bug was 100% not reproducible.