fix: untrack new comments only on actual unmount or interaction

[Soxasora]

Description

Fixes #2927
New comment outlining and tracking happens within a useEffect that depends on lastCommentAt and meCommentsViewedAt of the root item.

Live comments would inject a new comment updating the very same fields the effect depends on, triggering the effect cleanup that untracks new comments. The same class of changes were likely happening with any other cache mod to root, like a zap.

Screenshots

dedicated-navigator-cleanup-before-after.mov

Additional Context

This didn't happen in React 18/Apollo Client 3. A theory can be that React 19 has different render scheduling/transitions.

Zap -> navigator clear cannot be reproduced in dev for some reason. Tracing untrackNewComment in Chrome DevTools showed that the useEffect cleanup, that untracks new comments, runs also after a zap or live comment.

Checklist

Are your changes backward compatible? Please answer below:

yes

On a scale of 1-10 how well and how have you QA'd this change and any features it might affect? Please answer below:

5, could only verify the live comments bug, but it's in the same class/behavior of the zap->untrack bug.

Did you use AI for this? If so, how much did it assist you?
no

---

Note

Medium Risk
Adjusts React effect timing around new-comment tracking/untracking; mistakes could cause missed outlines, incorrect counts, or sticky navigator state on item pages.

Overview
Fixes premature removal of “new comment” tracking/outline by tracking each comment at most once and only untracking on real unmount.

Comment now keeps a didTrackRef flag to avoid re-registering on re-renders/cache updates and moves the untrackNewComment call into an unmount-only cleanup. use-comments-navigator makes trackNewComment synchronous and returns whether insertion occurred, enabling immediate, reliable untracking on user interaction.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[huumn]

bot review claims to have found a regression:

This looks like a regression from the new didTrackRef tracking lifetime. The fix avoids dependency cleanup untracking live comments too early, but now marks the comment as tracked before trackNewComment actually inserts it on the next animation frame.

If the user dismisses the outline before that RAF runs, the pending insert can still add the comment back after it was untracked, and unmount cleanup may skip it because didTrackRef was reset to false.

Suggested patch: make trackNewComment register synchronously and return whether the ref was actually tracked, then set didTrackRef.current from that return value.

[Soxasora]

We don't even need the RAF for tracking new comments, I remember implementing it just to micro-optimize and follow the same pattern of throttleCountUpdate but it's pretty much useless, it's useful only to update the count without causing too many re-renders due to the context.

Fixed! Thank you!!