fix(view): preserve cycled layout across force_entry_refresh_on_noop

[dlyongemallo]

Fixes #312.

[Copilot]

🟢 Approval recommended

The change is a minimal, correctly-guarded fix that mirrors the established convert_layout pattern (e.g. file_history_view.lua:405-408), covers all file collections, and is backed by a targeted regression test with valid API usage.

Pull request overview

This PR fixes issue #312, where the diff layout chosen via cycle_layout/set_layout (e.g. g<C-x>) was silently reset to the config default whenever a refresh replaced NOOP entries. This happens on adapters where force_entry_refresh_on_noop returns true — notably the jj adapter on any LOCAL-touching range, which fires on tab_enter, FocusGained, polling, or an explicit R. Because get_updated_files always rebuilds entries with the config default layout, the fix carries the old entry's layout class onto the freshly built entry before the swap, using the existing FileEntry:convert_layout mechanism.

Changes:

• In the NOOP replace-entry branch of update_files_impl, convert the new entry to the old entry's layout class when they differ, preserving the user's cycled/set layout across refreshes.
• Add a regression test simulating the force_entry_refresh_on_noop replace path and asserting the recreated entry keeps the user's chosen layout class.

File summaries

File	Description
lua/diffview/scene/views/diff/diff_view.lua	Preserves the old entry's layout class on the replacement entry in the NOOP force-refresh branch.
lua/diffview/tests/functional/diff_view_spec.lua	Adds a regression test verifying the layout class survives the entry swap.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

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[jakubbortlik]

Hi David, thanks for addressing this. When I was trying to figure out what's wrong, Claude Code suggested that maybe the JjAdapter:force_entry_refresh_on_noop is obsolete and should be removed. Supposedly, "the staleness it guards against is now handled by
JjAdapter:on_local_buffer_reused (jj/init.lua:690-700)" - but I don't know enough about diffview's codebase to judge if this is indeed the case.

One thing I can confirm though is that removing the JjAdapter:force_entry_refresh_on_noop override removes one more bug: When on the 312-layout_selection branch and when inspecting a file I do :DiffviewOpen main the diffiview now correctly retains the layout, but the cursor position is lost and more over, switching back and forth to the original tab from which I opened the diffview, the original tab is closed. When I simply remove JjAdapter:force_entry_refresh_on_noop or make it return false, both issues are gone (not sure though, if that introduces other issues, but I haven't noticed any).