532a071715
Uses GeometryReader + coordinate space to track entry positions —
NOT onAppear/onDisappear.
How it works:
1. ScrollView has a named coordinate space ("readerScroll")
2. Invisible anchor at top measures scroll offset via PreferenceKey
3. Each entry row has a background GeometryReader that tracks its
frame in the scroll coordinate space
4. onChange(of: maxY) detects when an entry's bottom edge crosses
above the viewport top (oldMaxY >= 0 → newMaxY < 0)
5. Entry is marked read only when ALL conditions are true:
- trackingActive (user scrolled down >100pt)
- isScrollingDown (current direction is down)
- entry is unread
- entry hasn't been marked by scroll already
- entry's bottom edge just crossed above viewport
Navigation protection:
- onAppear resets trackingActive = false and cumulativeDown = 0
- When returning from an article, tracking is suspended
- User must scroll down 100pt before tracking reactivates
- This prevents all visible entries from being marked read on
navigation back (they were already below viewport, not crossing)
- Scrolling up never marks anything (isScrollingDown = false)
State updates are local-first (immediate) with background API sync.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>