DiffViewer now uses IntersectionObserver to replace off-viewport FileCards with
48px placeholder divs, eliminating thousands of DOM nodes at initial render for
large diffs. Files within 1× viewport buffer are rendered as real FileCards.
FileCard defaults to collapsed state and only fires getFileDiff when expanded,
with staleTime: Infinity to avoid re-fetches. Handles loading/error/binary/
no-hunks states. Commit mode passes detail prop to skip lazy loading entirely.
DiffViewer batches expand-all in chunks of 10, prefetching via tRPC utils to
saturate the network without blocking the UI.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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