Fix stale settings saves resetting style selection

[snvtac]

User description

Summary

• Preserve style-pack-owned preference fields when generic settings saves persist a full preferences payload.
• Add a locked PreferencesStore write path so a stale settings payload cannot roll back the current active style pack.
• Emit the actual saved preferences after set_settings and set_update_channel persist.

Root Cause

Generic settings saves send a complete UserPreferences snapshot. If the user switches to a local style pack and a later settings save uses an older snapshot, that stale payload can overwrite active_style_pack_id and related legacy style fields, sending the app back to the previous formal/builtin style.

Fix

The generic settings save path now treats style-pack preferences as owned by the style-pack commands. Before writing a generic settings payload, PreferencesStore::set_preserving_current_style_preferences copies the current store style fields under the same store lock used for the disk write and in-memory update. Style-pack commands still use the normal store write path, so intentional style changes continue to persist.

Fixes #742.

Validation

• rustfmt --edition 2021 --check openless-all/app/src-tauri/src/commands/settings.rs openless-all/app/src-tauri/src/persistence/preferences.rs openless-all/app/src-tauri/src/types.rs
• cargo test settings
• cargo test sync_style_pack_preferences
• cargo test set_preserving_current_style_preferences
• git diff --check

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PR Type

Bug fix, Enhancement

---

Description

• Preserve active style preferences when generic settings saves overwrite them.

• Add write_settings_preserving_current_style_preferences method to SettingsWriter.

• Modify persist_settings, set_settings, and set_update_channel to use the new path.

• Add unit tests for the new behavior.

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Diagram Walkthrough

flowchart LR
  A["User switches style pack"] --> B["Style pack command writes prefs via normal path"]
  C["Generic settings save triggered"] --> D["Read current prefs from store"]
  D --> E["Call preserve_style_preferences_from"]
  E --> F["Write merged prefs (keeps style)"]
  B --> G["Style change persists"]
  F --> G
  G --> H["Frontend receives updated prefs"]

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File Walkthrough

	Relevant files
Bug fix	settings.rs Add style-preserving write path to SettingsWriter                openless-all/app/src-tauri/src/commands/settings.rs Added write_settings_preserving_current_style_preferences method to SettingsWriter trait. Replaced write_settings calls with the preserving variant in persist_settings_with_keyboard_apply and persist_settings. Updated set_settings to read back the saved prefs after writing. Added unit tests settings_save_preserves_current_style_preferences_before_write and persist_settings_keeps_style_change_that_lands_before_write. +141/-10
Enhancement	preferences.rs Add style-preserving write to PreferencesStore                      openless-all/app/src-tauri/src/persistence/preferences.rs Added set_preserving_current_style_preferences method to PreferencesStore. Method copies current store style fields into the incoming payload before writing. Added unit test set_preserving_current_style_preferences_keeps_store_style_fields. +53/-1    types.rs Add preserve_style_preferences_from to UserPreferences      openless-all/app/src-tauri/src/types.rs Added preserve_style_preferences_from method to UserPreferences. Method copies default_mode, enabled_modes, active_style_pack_id, style_system_prompts, and custom_style_prompts from another instance. +10/-0

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[github-actions]

PR Reviewer Guide 🔍

(Review updated until commit 117aa1b)

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 742 - Partially compliant Compliant requirements: After selecting a local style pack, the selection should persist after app restart or waiting. Subsequent writings/edits should use the last activated style pack, not revert to formal. Non-compliant requirements: If save fails or config is reset, the UI should give an observable error/hint.

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ No major issues detected

[H-Chris233]

Could you please resolve conflicts for this?
I reviewed this pr，If you resolve conflicts, i will merge it.

[H-Chris233]

@appergb 你有时间的话cherry pick一下吧，作者不回复了，或者直接将此工作分配给我。

[H-Chris233]

接管

[github-actions]

Persistent review updated to latest commit 117aa1b

[H-Chris233]

接管