[heli-os]

Summary

Back from a Pokédex detail page always landed on page 1 of the grid, even when the species was opened from page 3. The catch log had the same problem: Back scrolled it to the top.

Why: CollectionView swaps the grid/log out for PokemonDetailView with an if/else. Opening a detail page unmounts DexGridView, which drops its @State page. Back mounts a fresh grid on page 1. The filters survived because they live one level up, in CollectionView.

Fix: CollectionView remembers what the detail page was opened from and hands it to the rebuilt view once.

• Pokédex: on Back, the grid opens on the page of the species just viewed (DexScrollPager.page(containing:in:pageSize:)). Nothing is selected, the same as the catch log. The page follows the species, not a page number, so:
  • opening a species from a Home sprite also returns to that species' page (previously page 1)
  • a catch that reorders the list while the detail page is open still lands on the right page
  • a species filtered out of the current results falls back to page 1, as before
• Catch log: the row that opened the detail page is scrolled back to the center. It scrolls twice. The first scrollTo places the row using estimated heights for the lazy rows, and once the rows it reveals are measured the target shifts (one row short on CI). The second scroll runs after that layout pass. scrollPosition(id:) was tried too: without anchor: (macOS 14) it overshot the end of the list and left the log blank.
• Both anchors are used once, so a later rebuild (switching segments) still starts at the top.

Commits are split as: pure page lookup + tests → Pokédex fix → catch log fix → defect-log entry → PR images → catch log correction from the first CI run (+ its defect-log note) → grid anchor set only when Back lands on the grid → grid anchor split from the selection (+ re-rendered image).

Type of change

• Bug fix
• New feature
• Refactor / cleanup
• Documentation
• Other:

UI changes

Sample-data renders of the production CollectionView (offline fixture, so the detail page shows its "could not be loaded" state). The "Before" column is the state Back produced before this change: a freshly built grid/log, rendered from the same fixture.

Pokédex: open #18 Pidgeot (page 2), e.g. from its Home sprite, then press Back.

Before	After

Catch log: scroll down, open Butterfree's entry, then press Back.

Before	After

Checklist

• swift build and swift test pass locally
• PR title follows Conventional Commits and title/description are written in English
• UI changes include embedded images (before/after for existing screens; image of a new screen), or there is no visible UI change
• No copyrighted assets, secrets, or private tooling references are committed (see CONTRIBUTING)
• Tests were added or updated for this change

Tests

• DexScrollPagerTests: page lookup for first/last page, the 16th/17th boundary, nil, and filtered-out IDs.
• DexBackNavigationTests (new): hosts the real CollectionView in a window, does the detail → Back round trip, and reads the result off the rendered pixels with Vision. The accessibility tree is empty without an AX client, so it can't be used here. Each guard was checked by injecting the defect: removing the anchor, the one-time use, the log anchor, or the second log scroll, keeping the grid anchor after a Back to the log, or letting the anchor select the species each makes a test fail. Presses retry until the screen changes, because right after a transition the view tree can still hit-test the previous screen (a missed Back press on the first CI run).
• Full suite: 1514 tests, 0 failures (15 skipped), logic-core line coverage 93.74% (threshold 75%). Every new branch runs in tests (llvm-cov show, no ^0).
  • Two earlier full runs on a heavily loaded machine each had unrelated flaky failures (SessionKeySettingsRenderingTests, then SpriteImageCacheTests/UnownSpriteCacheTests). They pass alone and together with the new tests.
  • Locally, test-gate.sh couldn't locate the test binary under Xcode's Swift 6.4 build layout, so the coverage numbers above come from running its llvm-cov report step by hand. CI runs the gate as usual.

🤖 Generated with Claude Code

[chattymin]

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