In feed agents highlight

[tomeredlich]

Changes

Events

Did you introduce any new tracking events?

Experiment

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Manual Testing

Caution

Please make sure existing components are not breaking/affected by this PR

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PR Review: In feed agents highlight

• Gathering context
• Reading changed files
• Analyzing code
• Posting review

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Summary

This PR adds a "Happening Now" highlights module to the top of My Feed, backed by a POST_HIGHLIGHTS_QUERY GraphQL query and gated behind a featureFeedHighlightsModule feature flag (+ development override). The component also ships scaffolding for a "v2" floating widget/minimizable popover that is never activated.

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Issues

🔴 Dead code: isFeedHighlightsUi2Enabled = false

FeedHighlightsTopModule.tsx:40 has this hardcoded:

const isFeedHighlightsUi2Enabled = false;

This constant gates a very large block of code that never executes: the entire floating popover section (~90 lines), the collapsed button section (~30 lines), unreadCount state, isPopoverOpen state, isDismissed state, the scroll listener effect, the simulate event listener, the minimize cooldown localStorage logic, and three useEffect hooks. Per the CLAUDE.md "Delete dead code" guideline, this should be removed if the feature isn't being shipped in this PR, or activated and tested if it is.

Fix this →

🔴 Dead CSS: .feed-highlights-menu-content never applied

utilities.css:678-686 defines:

.feed-highlights-menu-content {
  min-width: 12rem;
  ...
}
.feed-highlights-menu-content .DropdownMenuItem {
  height: 1.5rem;
  ...
}

But className="feed-highlights-menu-content" is never applied to <DropdownMenuContent> in FeedHighlightsTopModule.tsx (line 396). These styles have no effect. Either apply the class or remove the CSS.

Similarly, the notification-bubble-enter keyframe animation added to utilities.css:112-123 is never referenced anywhere in the component.

Fix this →

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Observations

🟡 highlightAsNew is always index === 0

FeedHighlightsTopModule.tsx:413:

highlightAsNew={index === 0}

The first highlight always shows "Now" as the timestamp regardless of its actual age. This is probably intentional UX but worth confirming — if a highlight is 3 hours old it would still show "Now".

🟡 markHighlightViewed / markHighlightRead defined inside render

These functions at lines 354-375 are recreated on every render. They don't need to be defined inside the render body since they only call setState. They could be useCallback hooks or at minimum defined outside the if check block. Minor since HighlightRow isn't memoized, but inconsistent with the pattern used for callbacks in Feed.tsx.

🟡 No staleTime on the highlights query

Feed.tsx:344-351 — TanStack Query defaults to staleTime: 0, meaning the highlights will refetch every time the window regains focus. For a "Happening Now" module this may be intentional (always fresh data), but it's worth explicitly documenting or setting a staleTime if refetching on focus isn't desired.

🟡 digestSource as Source unsafe cast

FeedHighlightsTopModule.tsx:145:

const { isFollowing, toggleFollow } = useSourceActions({
  source: digestSource as Source,
});

digestSource may be undefined (query is loading or errored), and the cast bypasses TypeScript's null safety. Confirm useSourceActions handles an undefined source gracefully.

🟢 Good patterns

• Feature flag gated with shouldEvaluate: isMyFeed to avoid unnecessary GrowthBook evaluations ✓
• isDevelopment override for local dev testing ✓
• Impression tracking with ref guard to avoid double-firing ✓
• prefers-reduced-motion respected for gradient animations ✓
• type="button" set on all buttons ✓
• Proper RequestKey.PostHighlights used for query key ✓

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