Description

Better implements

1. activity state for connected collaborators on a workflow showing their current state being active|away. also deals with when they switch from the tab and back.
2. maintains our 10s ydoc keep-alive trigger updates using lastSeen.

What was causing the flickering?

• ydoc requires us to update a user's state within a 30s interval to keep them considered in awareness(being online)
• due to this, we have a setInterval which updates the user's lastSeen every 10s, just so we are in the 30s interval
• we try to do this all the time but some browsers have a smart way of saving resources which is to throttle JS execution on tabs that aren't active(user has switched away from)
• when this happens, JS timers like setInterval start to miss their interval calls. eg. a 10s interval call might be actually triggered after 60s.
• hence, we start missing the 30s requirement by ydoc and then ydoc removes all users who have started missing the time.
• but if a user missed the 30s threshold and got called after 60s due to throttling. it shows a flicker on all other active collaborator. because the user was removed when they missed 30s but got back in awareness when their throttled trigger came in after 60s.

Approach taken

• we keep our 10s interval trigger to ydoc
• we have another field lastState controlled by the browser visibility API to track whether a user is active or away

How do we smoothing the presence of a user to avoid the flickering?

• Now, we only cache a user in awareness for 60s when they are away. (throttling likely happens to away users)
• If they're away and keep showing up in awareness, we give that precedence over what's in the cache. (probably they're not throttled)
• As soon as they come back to active, we dont wait for TTL of cache but just remove them from cache. (throttling never happens to active users)

Closes #3931

Validation steps

1. (How can a reviewer validate your work?)

Additional notes for the reviewer

1. (Is there anything else the reviewer should know or look out for?)

AI Usage

Please disclose how you've used AI in this work (it's cool, we just want to know!):

• Code generation (copilot but not intellisense)
• Learning or fact checking
• Strategy / design
• Optimisation / refactoring
• Translation / spellchecking / doc gen
• Other
• I have not used AI

You can read more details in our Responsible AI Policy

Pre-submission checklist

• I have performed a self-review of my code.
• I have implemented and tested all related authorization policies. (e.g., :owner, :admin, :editor, :viewer)
• I have updated the changelog.
• I have ticked a box in "AI usage" in this PR