[mejo-]

📝 Summary

Follow-up to #2699 and #2700.

This replaces the version comparison added in #2699 and #2700 with a much smaller implementation, similar to what nextcloud/text#9293 did for Text. Text now shows the differences between two Markdown versions in the viewer itself, so Collectives no longer needs a comparison dialog of its own.

• Comparing a version with the current one opens the viewer again. With a recent Text, it shows Text's comparison: both documents side by side with the changes highlighted, synced scrolling and navigation between changes. Older Text versions show the plain side-by-side view.
• A new "Compare versions…" button in the versions tab opens a small dialog for picking any two versions.
• Members without edit permissions keep the versions tab and can compare versions.

Removed, as Text and the viewer handle it now or it isn't needed:

• the comparison dialog with its own snapshot loading, caching, size limits and error handling
• shareable comparison links (compareFrom / compareTo).
• the separate CI setup for the comparison tests (semantic-e2e matrix entries, extra Playwright projects, Cypress flags)

Fixed along the way:

• On Nextcloud 36, comparing failed for pages whose names need URL encoding, e.g. with a space: the viewer requested a double-encoded URL.
• Comparing again while a comparison was open showed an endless spinner. Text loads the compared versions only once, so the viewer is closed before comparing other versions. This should be fixed in Text as well.
• Opening a comparison from the versions tab switched the page sidebar to the attachments tab.
• Versions loaded for a page that was no longer open replaced the versions list of the current page.

🚧 TODO

• Allow to switch versions in viewer without having to reload it?
• Set better titles for versions in viewer?

🏁 Checklist

• Code is properly formatted (npm run lint / npm run stylelint / composer run cs:check)
• Sign-off message is added to all commits
• Tests (unit, integration and/or end-to-end) passing and the changes are covered with tests

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI tools
• The AI-generated content was reviewed, comprehended and tested by a human

[hweihwang]

Thanks Jonas, much less code to carry, and on 36 it works well for me. Two things, not blocking:

1. Comparing with the current version no longer saves the editor first, so the last seconds of typing can be missing from "Current version". Keeping the save before comparing would cover it.
2. On 35, attachments may not load in the comparison: Collectives passes fileId, while Text stable35 reads OCA.Viewer.fileInfo.fileid. I only checked this in the code, not on a 35 instance.

[mejo-]

Thanks Hoang!

Comparing with the current version no longer saves the editor first, so the last seconds of typing can be missing from "Current version". Keeping the save before comparing would cover it.

I first thought that we can leave this out as the new autosave logic in text is pretty good. But then I thought about it again and agree that now that we're on it, it's worth to fix this also straight away. There's the possibility of a delay of up to 10 seconds in autosave, so it's worth to save manually before comparing with current version. Fixed now.

On 35, attachments may not load in the comparison.

Indeed, good catch. Also fixed and a test added now.