[devin-ai-integration]

Summary

Views in arca-gui/src/ui/ wrote straight into AppState/Settings and called Settings::save() themselves, which silently dropped I/O errors. They also kept two copies of the codec/level picker that had drifted apart. The active pane's state was stored twice: in the legacy AppState fields and in browser.panes[active], kept in sync by snapshot_active_pane/restore_active_pane. Behavior is unchanged, except that a failed settings write now shows an error notice.

Active pane: one copy of its state (commit 1)

• Removed AppState::{checked, filter, order, current_dir, cursor}. DirectoryPane::selected: HashSet<usize> is now checked: Vec<bool>.
• AppState::active_pane() / active_pane_mut() return &browser.panes[browser.active]. snapshot_active_pane/restore_active_pane are gone. Switching panes calls pane_switched(), which does what restore did: resizes the pane's checked to entries.len() and clears last_click, renaming and the preview.
• select_only (added on main in refactor(arca-gui): select a single row through one controller action #72 as AppAction::SelectOnly) now clears active_pane_mut().checked and no longer needs a snapshot.

Settings persistence

Settings::save(&self) -> io::Result<()>           // was (), with `let _ =` on create_dir_all/write
AppController::update_settings(|s| ...) -> R      // mutate, save once, error -> set_notice(settings_not_saved, true)
AppController::set_column_width(slot, w, persist) // live drag updates, saved when the drag ends

Every settings.save() call in ui/ (dialogs including the theme library, header, sidebar, preview, browser, mod) and in the controller, including set_archive_defaults from #68, now goes through this path. New string settings_not_saved (en/es).

Compressor picker

• AppController::compressor_for(format, codec) -> Compressor::{Fixed("LZMA2"|"RAR"), Codec { codec, editable }} replaces the two copies of the is_lzma2/Format::Rar check. compressor() applies it to the session's state.format/state.codec. CODECS and LEVEL_PRESETS replace the inline arrays.
• Both dialogs use one codec_combo helper:
  • Settings > Defaults passes settings.new_format/new_codec to compressor_for and saves through set_archive_defaults.
  • The compress dialog uses compressor() and calls set_codec/set_level.
• Each dialog keeps its own layout: the settings page shows a level combo and a disabled combo for non-ZIP codecs, and the compress dialog shows a slider and a muted label.

Notices: set_notice(text, error) replaces the paired notice/error writes.

Tests

New tests: select_only_replaces_the_active_selection and only_zip_lets_the_codec_be_picked. #72's select_only test now checks panes[0].checked.

Ran locally: cargo fmt --check, cargo clippy --workspace --all-targets -D warnings, cargo test --workspace, both release builds, and bash interop.sh (146 passed).

Not covered:

• No test for the save-error path. It would need XDG_CONFIG_HOME set for the whole process, and the tests run in parallel.
• I didn't click through the GUI by hand.

Link to Devin session: https://app.devin.ai/sessions/f6cf7190c78d468b8c00be133c2d3a76
Open in Devin Desktop: https://app.devin.ai/desktop/session/f6cf7190c78d468b8c00be133c2d3a76?variant=devin
Requested by: @Villoh

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring