diff --git a/crates/nyaterm-core/src/storage.rs b/crates/nyaterm-core/src/storage.rs
index cfac10b10..e8bc58341 100644
--- a/crates/nyaterm-core/src/storage.rs
+++ b/crates/nyaterm-core/src/storage.rs
@@ -1,4 +1,3 @@
-use std::collections::HashMap;
 use std::path::{Path, PathBuf};
 use std::time::{SystemTime, UNIX_EPOCH};
 
@@ -8,18 +7,18 @@ use sha2::{Digest, Sha256};
 use thiserror::Error;
 
 use crate::{
-    AiSettings, AliyunDriveSyncSettings, AppSettingsSummary, CloudSyncSettings, CloudSyncState,
-    CredentialCrypto, CredentialCryptoError, Group, KeywordHighlightConfig,
-    KeywordHighlightImportResult, KeywordHighlightRule, OAuthDriveSyncSettings,
-    PortableSnapshotError, ProxyConfig, ProxyGroup, ProxyGroupsConfig, QuickCommand,
-    QuickCommandCategory, QuickCommandsConfig, SavedConnection, SearchEngineConfig, SessionsConfig,
-    TranslationSettings, TunnelConfig, TunnelGroup, TunnelGroupsConfig, ai_settings_has_secret,
-    default_search_engines, merge_masked_ai_settings, merge_masked_cloud_sync_settings,
+    AiSettings, AliyunDriveSyncSettings, CloudSyncSettings, CloudSyncState, CredentialCrypto,
+    CredentialCryptoError, Group, KeywordHighlightConfig, KeywordHighlightImportResult,
+    KeywordHighlightRule, OAuthDriveSyncSettings, PortableSnapshotError, ProxyConfig, ProxyGroup,
+    ProxyGroupsConfig, QuickCommand, QuickCommandCategory, QuickCommandsConfig, SavedConnection,
+    SessionsConfig, TranslationSettings, TunnelConfig, TunnelGroup, TunnelGroupsConfig,
+    ai_settings_has_secret, merge_masked_ai_settings, merge_masked_cloud_sync_settings,
     merge_masked_translation_settings, normalize_ai_settings, translation_settings_has_secret,
     uuid,
 };
 
 mod ai_history;
+mod app_settings;
 mod command_history;
 mod config_backup;
 mod keyword_highlights;
@@ -429,1252 +428,6 @@ impl ConnectionStore {
         Ok(())
     }
 
-    pub fn load_app_settings_summary(&self) -> Result<AppSettingsSummary, StorageError> {
-        let value = self.load_settings_value()?;
-        Ok(AppSettingsSummary {
-            theme: json_string(&value, &["appearance", "theme"], "github-dark"),
-            background_image_path: json_path(&value, &["appearance", "background_image_path"])
-                .and_then(|v| v.as_str())
-                .map(str::trim)
-                .filter(|s| !s.is_empty())
-                .map(|s| s.to_string()),
-            background_image_fit: json_string(
-                &value,
-                &["appearance", "background_image_fit"],
-                "cover",
-            ),
-            background_image_opacity: {
-                let raw = json_path(&value, &["appearance", "background_image_opacity"]);
-                let pct = raw
-                    .and_then(|v| v.as_f64())
-                    .map(|v| {
-                        // Accept both 0..1 float (Tauri) and 0..100 percent.
-                        if v <= 1.0 {
-                            (v * 100.0).round() as u8
-                        } else {
-                            v.round() as u8
-                        }
-                    })
-                    .unwrap_or(45)
-                    .clamp(0, 100);
-                pct
-            },
-            background_content_opacity: {
-                let raw = json_path(&value, &["appearance", "background_opacity"]);
-                let pct = raw
-                    .and_then(|v| v.as_f64())
-                    .map(|v| {
-                        if v <= 1.0 {
-                            (v * 100.0).round() as u8
-                        } else {
-                            v.round() as u8
-                        }
-                    })
-                    .unwrap_or(82)
-                    .clamp(0, 100);
-                pct
-            },
-            // Tauri UiConfig.language (not translation.target_language).
-            language: json_string(&value, &["ui", "language"], "en"),
-            terminal_font_family: json_string(
-                &value,
-                &["appearance", "font_family"],
-                "JetBrains Mono",
-            ),
-            terminal_font_size: json_u16(&value, &["appearance", "font_size"], 16),
-            cursor_style: {
-                let raw = json_string(&value, &["appearance", "cursor_style"], "block");
-                match raw.as_str() {
-                    "underline" | "bar" | "block" => raw,
-                    _ => "block".to_string(),
-                }
-            },
-            cursor_blink: json_bool(&value, &["appearance", "cursor_blink"], true),
-            terminal_theme: {
-                let raw = json_path(&value, &["appearance", "terminal_theme"])
-                    .and_then(|v| v.as_str())
-                    .map(str::trim)
-                    .filter(|s| !s.is_empty())
-                    .map(|s| s.to_string());
-                raw
-            },
-            minimum_contrast_ratio: {
-                let raw = json_path(&value, &["appearance", "minimum_contrast_ratio"]);
-                let num = raw.and_then(|v| {
-                    v.as_f64()
-                        .or_else(|| v.as_str().and_then(|s| s.parse::<f64>().ok()))
-                });
-                match num {
-                    Some(1.0) => "1".to_string(),
-                    Some(3.0) => "3".to_string(),
-                    Some(4.5) => "4.5".to_string(),
-                    Some(7.0) => "7".to_string(),
-                    Some(21.0) => "21".to_string(),
-                    _ => "1".to_string(),
-                }
-            },
-            ui_font_family: json_string(&value, &["appearance", "ui_font_family"], "Inter"),
-            ui_font_size: json_u16(&value, &["appearance", "ui_font_size"], 16).clamp(12, 24),
-            terminal_font_weight: {
-                let w = json_u16(&value, &["appearance", "font_weight"], 400);
-                match w {
-                    300 | 400 | 500 | 600 | 700 | 800 => w,
-                    _ => 400,
-                }
-            },
-            terminal_font_weight_bold: {
-                let w = json_u16(&value, &["appearance", "font_weight_bold"], 700);
-                match w {
-                    300 | 400 | 500 | 600 | 700 | 800 => w,
-                    _ => 700,
-                }
-            },
-            x11_display: json_string(&value, &["terminal", "x11_display"], ""),
-            terminal_scrollback_lines: json_u32(&value, &["terminal", "scrollback_lines"], 5000)
-                .clamp(100, 100_000),
-            terminal_keep_alive_interval: json_u32(
-                &value,
-                &["terminal", "keep_alive_interval"],
-                30,
-            )
-            .min(600),
-            terminal_hardware_acceleration: json_bool(
-                &value,
-                &["terminal", "hardware_acceleration"],
-                true,
-            ),
-            terminal_show_workspace_padding: json_bool(
-                &value,
-                &["terminal", "show_workspace_padding"],
-                false,
-            ),
-            terminal_show_line_numbers: json_bool(
-                &value,
-                &["terminal", "show_line_numbers"],
-                false,
-            ),
-            terminal_show_timestamps: json_bool(&value, &["terminal", "show_timestamps"], false),
-            terminal_show_timestamp_milliseconds: json_bool(
-                &value,
-                &["terminal", "show_timestamp_milliseconds"],
-                false,
-            ),
-            terminal_show_multi_line_paste_dialog: json_bool(
-                &value,
-                &["terminal", "show_multi_line_paste_dialog"],
-                true,
-            ),
-            terminal_paste_image_as_path: json_bool(
-                &value,
-                &["terminal", "paste_image_as_path"],
-                true,
-            ),
-            terminal_low_latency_mode: json_bool(&value, &["terminal", "low_latency_mode"], false),
-            terminal_action_links_enabled: json_bool(
-                &value,
-                &["terminal", "action_links_enabled"],
-                false,
-            ),
-            terminal_action_links_matchers: load_action_links_matchers(&value),
-            search_custom_engines: load_search_engines(&value),
-            ui_show_remote_stats: json_bool(&value, &["ui", "show_remote_stats"], true),
-            ui_remote_stats_interval: json_u32(&value, &["ui", "remote_stats_interval"], 3)
-                .clamp(1, 60),
-            ui_show_process_manager: json_bool(&value, &["ui", "show_process_manager"], true),
-            ui_process_manager_interval: json_u32(&value, &["ui", "process_manager_interval"], 5)
-                .clamp(3, 120),
-            ui_show_docker_manager: json_bool(&value, &["ui", "show_docker_manager"], true),
-            ui_docker_manager_interval: json_u32(&value, &["ui", "docker_manager_interval"], 10)
-                .clamp(3, 120),
-            ui_quick_cmd_view_mode: normalize_quick_cmd_view_mode(&json_string(
-                &value,
-                &["ui", "quick_cmd_view_mode"],
-                "tile",
-            )),
-            ui_quick_cmd_sort_mode: normalize_quick_cmd_sort_mode(&json_string(
-                &value,
-                &["ui", "quick_cmd_sort_mode"],
-                "created",
-            )),
-            ui_saved_connections_sort_mode: normalize_saved_connections_sort_mode(&json_string(
-                &value,
-                &["ui", "saved_connections_sort_mode"],
-                "default",
-            )),
-            ui_file_explorer_auto_sync_cwd_connection_ids: json_string_vec(
-                &value,
-                &["ui", "file_explorer_auto_sync_cwd_connection_ids"],
-                256,
-            ),
-            ui_file_explorer_favorite_dirs_by_connection_id: json_string_vec_map(
-                &value,
-                &["ui", "file_explorer_favorite_dirs_by_connection_id"],
-                12,
-            ),
-            ui_left_panel_width: json_u32(&value, &["ui", "left_width"], 256).clamp(160, 720),
-            ui_right_panel_width: json_u32(&value, &["ui", "right_width"], 288).clamp(200, 720),
-            ui_transfer_height: json_u32(&value, &["ui", "transfer_height"], 180).clamp(60, 600),
-            ui_quick_cmd_height: json_u32(&value, &["ui", "quick_cmd_height"], 180).clamp(36, 520),
-            ui_quick_cmd_visible: json_bool(&value, &["ui", "show_quick_cmd_bar"], true),
-            ui_serial_send_height: json_u32(&value, &["ui", "serial_send_height"], 180)
-                .clamp(60, 520),
-            ui_serial_send_visible: json_bool(&value, &["ui", "show_serial_send_panel"], false),
-            ui_active_left_panel: json_optional_string(&value, &["ui", "active_left_panel"]),
-            ui_active_right_panel: json_optional_string(&value, &["ui", "active_right_panel"]),
-            ui_left_panel_collapsed: json_bool(&value, &["ui", "left_panel_collapsed"], false),
-            ui_right_panel_collapsed: json_bool(&value, &["ui", "right_panel_collapsed"], false),
-            ui_activity_bar_left_top: {
-                json_string_vec_with_default(
-                    &value,
-                    &["ui", "activity_bar_layout", "left_top"],
-                    32,
-                    default_activity_left_top,
-                )
-            },
-            ui_activity_bar_left_bottom: {
-                json_string_vec_with_default(
-                    &value,
-                    &["ui", "activity_bar_layout", "left_bottom"],
-                    32,
-                    default_activity_left_bottom,
-                )
-            },
-            ui_activity_bar_right_top: {
-                json_string_vec_with_default(
-                    &value,
-                    &["ui", "activity_bar_layout", "right_top"],
-                    32,
-                    default_activity_right_top,
-                )
-            },
-            ui_activity_bar_right_bottom: {
-                json_string_vec_with_default(
-                    &value,
-                    &["ui", "activity_bar_layout", "right_bottom"],
-                    32,
-                    default_activity_right_bottom,
-                )
-            },
-            ui_activity_bar_show_labels: json_bool(
-                &value,
-                &["ui", "activity_bar_layout", "show_labels"],
-                false,
-            ),
-            ui_panel_multi_open: json_bool(&value, &["appearance", "panel_multi_open"], false)
-                || json_bool(&value, &["ui", "panel_multi_open"], false),
-            ui_left_open_panels: json_string_vec(&value, &["ui", "left_open_panels"], 32),
-            ui_right_open_panels: json_string_vec(&value, &["ui", "right_open_panels"], 32),
-            ui_panel_stack_sizes: json_u32_map(&value, &["ui", "panel_stack_sizes"]),
-            interaction_copy_on_select: json_bool(
-                &value,
-                &["interaction", "copy_on_select"],
-                false,
-            ),
-            interaction_right_click_paste: json_bool(
-                &value,
-                &["interaction", "right_click_paste"],
-                false,
-            ),
-            interaction_command_suggestions_enabled: json_bool(
-                &value,
-                &["interaction", "command_suggestions_enabled"],
-                true,
-            ),
-            interaction_command_suggestion_min_chars: json_u32(
-                &value,
-                &["interaction", "command_suggestion_min_chars"],
-                2,
-            )
-            .clamp(1, 500),
-            interaction_command_suggestion_max_chars: json_u32(
-                &value,
-                &["interaction", "command_suggestion_max_chars"],
-                64,
-            )
-            .clamp(1, 500),
-            interaction_word_separators: json_string(
-                &value,
-                &["interaction", "word_separators"],
-                " \t\r\n\"'`~!@#$%^&*()-=+[{]}\\|;:,<.>/?",
-            ),
-            interaction_duplicate_session_command_delay_ms: json_u32(
-                &value,
-                &["interaction", "duplicate_session_command_delay_ms"],
-                1000,
-            )
-            .min(60_000),
-            interaction_alt_as_meta: json_bool(&value, &["interaction", "alt_as_meta"], false),
-            interaction_mac_ime_compatibility: json_bool(
-                &value,
-                &["interaction", "mac_ime_compatibility"],
-                true,
-            ),
-            interaction_tab_double_click_action: normalize_tab_mouse_action(&json_string(
-                &value,
-                &["interaction", "tab_double_click_action"],
-                "disconnect_session",
-            )),
-            interaction_tab_middle_click_action: normalize_tab_mouse_action(&json_string(
-                &value,
-                &["interaction", "tab_middle_click_action"],
-                "rename_tab",
-            )),
-            interaction_tab_right_click_action: normalize_tab_mouse_action(&json_string(
-                &value,
-                &["interaction", "tab_right_click_action"],
-                "none",
-            )),
-            interaction_default_encoding: normalize_interaction_encoding(&json_string(
-                &value,
-                &["interaction", "default_encoding"],
-                "UTF-8",
-            )),
-            host_key_policy: normalize_host_key_policy(&json_string(
-                &value,
-                &["security", "host_key_policy"],
-                "prompt",
-            )),
-            transfer_download_path: json_string(&value, &["transfer", "download_path"], ""),
-            transfer_ask_save_location: json_bool(
-                &value,
-                &["transfer", "ask_save_location"],
-                false,
-            ),
-            transfer_duplicate_strategy: normalize_transfer_duplicate_strategy(&json_string(
-                &value,
-                &["transfer", "duplicate_strategy"],
-                "ask",
-            )),
-            transfer_editor_type: normalize_transfer_editor_type(&json_string(
-                &value,
-                &["transfer", "editor_type"],
-                "external",
-            )),
-            transfer_default_editor: json_string(&value, &["transfer", "default_editor"], ""),
-            transfer_download_threads: json_u32(&value, &["transfer", "download_threads"], 3)
-                .clamp(1, 10),
-            transfer_upload_threads: json_u32(&value, &["transfer", "upload_threads"], 3)
-                .clamp(1, 10),
-            transfer_max_retries: json_u32(&value, &["transfer", "max_transfer_retries"], 2)
-                .min(10),
-            transfer_buffer_size: json_u32(&value, &["transfer", "transfer_buffer_size"], 32)
-                .clamp(8, 256),
-            transfer_default_file_permissions: normalize_transfer_file_permissions(&json_string(
-                &value,
-                &["transfer", "default_file_permissions"],
-                "644",
-            )),
-            transfer_preserve_timestamps: json_bool(
-                &value,
-                &["transfer", "preserve_timestamps"],
-                true,
-            ),
-            transfer_resume_broken_transfer: json_bool(
-                &value,
-                &["transfer", "resume_broken_transfer"],
-                true,
-            ),
-            recording_path: json_string(&value, &["transfer", "recording_path"], ""),
-            recording_auto_start: json_bool(&value, &["transfer", "recording_auto_start"], false),
-            recording_include_io_labels: json_bool(
-                &value,
-                &["transfer", "recording_include_io_labels"],
-                true,
-            ),
-            recording_include_timestamps: json_bool(
-                &value,
-                &["transfer", "recording_include_timestamps"],
-                true,
-            ),
-            recording_memory_limit_bytes: json_u64(
-                &value,
-                &["transfer", "recording_memory_limit_bytes"],
-                5 * 1024 * 1024,
-            ),
-            diagnostics_level: {
-                let raw = json_string(&value, &["diagnostics", "level"], "info");
-                match raw.as_str() {
-                    "warn" | "debug" => raw,
-                    _ => "info".to_string(),
-                }
-            },
-            diagnostics_retention_days: {
-                let days = u32::from(json_u16(&value, &["diagnostics", "retention_days"], 7));
-                match days {
-                    3 | 7 | 14 | 30 => days,
-                    _ => 7,
-                }
-            },
-            startup_restore: json_bool(&value, &["general", "startup_restore"], false),
-            startup_restore_window_layout: json_bool(
-                &value,
-                &["general", "startup_restore_window_layout"],
-                true,
-            ),
-            minimize_to_tray: json_bool(&value, &["general", "minimize_to_tray"], false),
-            confirm_on_close: json_bool(&value, &["general", "confirm_on_close"], true),
-            enable_screen_lock: json_bool(&value, &["security", "enable_screen_lock"], false),
-            idle_lock_minutes: u32::from(json_u16(&value, &["security", "idle_lock_minutes"], 0)),
-            has_master_password: value
-                .get("security")
-                .and_then(|security| security.get("master_password"))
-                .and_then(|master_password| master_password.as_str())
-                .is_some_and(|master_password| !master_password.is_empty()),
-            keybindings: json_string_map(&value, &["keybindings"]),
-        })
-    }
-
-    pub fn verify_master_password(&self, password: &str) -> Result<bool, StorageError> {
-        let Some(token) = self.load_encrypted_master_password()? else {
-            return Ok(true);
-        };
-        let bootstrap = CredentialCrypto::new(self.portable_key_path.clone(), None);
-        let stored = bootstrap.decrypt_settings_secret(&token)?;
-        Ok(stored == password)
-    }
-
-    pub fn save_master_password(
-        &self,
-        next_password: Option<&str>,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        if next_password.is_some_and(str::is_empty) {
-            return Err(StorageError::InvalidData(
-                "Master password cannot be empty when enabled".to_string(),
-            ));
-        }
-
-        let bootstrap = CredentialCrypto::new(self.portable_key_path.clone(), None);
-        let current_password = self
-            .load_encrypted_master_password()?
-            .map(|token| bootstrap.decrypt_settings_secret(&token))
-            .transpose()?;
-        let rewrapped_master_key = self
-            .load_master_key_token()?
-            .map(|token| {
-                CredentialCrypto::new(self.portable_key_path.clone(), current_password.clone())
-                    .rewrap_master_key_token(&token, next_password)
-            })
-            .transpose()?;
-
-        let mut value = self.load_settings_value()?;
-        let encoded_password = next_password
-            .map(|password| bootstrap.encrypt_settings_secret(password))
-            .transpose()?;
-        set_nested_json_value(
-            &mut value,
-            &["security", "master_password"],
-            encoded_password
-                .map(serde_json::Value::String)
-                .unwrap_or(serde_json::Value::Null),
-        );
-
-        let txn = self.db.begin_write()?;
-        write_json_in_txn(&txn, SETTINGS_TABLE, SETTINGS_DEFAULT, &value)?;
-        if let Some(token) = rewrapped_master_key.as_deref() {
-            txn.open_table(META_TABLE)?.insert(META_MASTER_KEY, token)?;
-            txn.open_table(TEXT_DOCS_TABLE)?
-                .insert(LEGACY_TEXT_MASTER_KEY, token)?;
-        }
-        txn.commit()?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_host_key_policy(&self, policy: &str) -> Result<AppSettingsSummary, StorageError> {
-        let policy = normalize_host_key_policy(policy);
-        let mut value = self.load_settings_value()?;
-        set_nested_json_string(&mut value, &["security", "host_key_policy"], policy);
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_recording_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_string(
-            &mut value,
-            &["transfer", "recording_path"],
-            settings.recording_path.clone(),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "recording_auto_start"],
-            serde_json::Value::Bool(settings.recording_auto_start),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "recording_include_io_labels"],
-            serde_json::Value::Bool(settings.recording_include_io_labels),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "recording_include_timestamps"],
-            serde_json::Value::Bool(settings.recording_include_timestamps),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "recording_memory_limit_bytes"],
-            serde_json::Value::from(settings.recording_memory_limit_bytes),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_transfer_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_string(
-            &mut value,
-            &["transfer", "download_path"],
-            settings.transfer_download_path.clone(),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "ask_save_location"],
-            serde_json::Value::Bool(settings.transfer_ask_save_location),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["transfer", "duplicate_strategy"],
-            normalize_transfer_duplicate_strategy(&settings.transfer_duplicate_strategy),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["transfer", "editor_type"],
-            normalize_transfer_editor_type(&settings.transfer_editor_type),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["transfer", "default_editor"],
-            settings.transfer_default_editor.clone(),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "download_threads"],
-            serde_json::Value::from(settings.transfer_download_threads.clamp(1, 10)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "upload_threads"],
-            serde_json::Value::from(settings.transfer_upload_threads.clamp(1, 10)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "max_transfer_retries"],
-            serde_json::Value::from(settings.transfer_max_retries.min(10)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "transfer_buffer_size"],
-            serde_json::Value::from(settings.transfer_buffer_size.clamp(8, 256)),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["transfer", "default_file_permissions"],
-            normalize_transfer_file_permissions(&settings.transfer_default_file_permissions),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "preserve_timestamps"],
-            serde_json::Value::Bool(settings.transfer_preserve_timestamps),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["transfer", "resume_broken_transfer"],
-            serde_json::Value::Bool(settings.transfer_resume_broken_transfer),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_file_explorer_favorite_dirs(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_value(
-            &mut value,
-            &["ui", "file_explorer_auto_sync_cwd_connection_ids"],
-            string_vec_json_value(&settings.ui_file_explorer_auto_sync_cwd_connection_ids, 256),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "file_explorer_favorite_dirs_by_connection_id"],
-            string_vec_map_json_value(
-                &settings.ui_file_explorer_favorite_dirs_by_connection_id,
-                12,
-            ),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_quick_command_ui_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_string(
-            &mut value,
-            &["ui", "quick_cmd_view_mode"],
-            normalize_quick_cmd_view_mode(&settings.ui_quick_cmd_view_mode),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["ui", "quick_cmd_sort_mode"],
-            normalize_quick_cmd_sort_mode(&settings.ui_quick_cmd_sort_mode),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_ui_layout_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_value(
-            &mut value,
-            &["ui", "left_width"],
-            serde_json::Value::from(settings.ui_left_panel_width.clamp(160, 720)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "right_width"],
-            serde_json::Value::from(settings.ui_right_panel_width.clamp(200, 720)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "transfer_height"],
-            serde_json::Value::from(settings.ui_transfer_height.clamp(60, 600)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "quick_cmd_height"],
-            serde_json::Value::from(settings.ui_quick_cmd_height.clamp(36, 520)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "show_quick_cmd_bar"],
-            serde_json::Value::Bool(settings.ui_quick_cmd_visible),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "serial_send_height"],
-            serde_json::Value::from(settings.ui_serial_send_height.clamp(60, 520)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "show_serial_send_panel"],
-            serde_json::Value::Bool(settings.ui_serial_send_visible),
-        );
-        match &settings.ui_active_left_panel {
-            Some(panel) if !panel.trim().is_empty() => {
-                set_nested_json_string(&mut value, &["ui", "active_left_panel"], panel.clone())
-            }
-            _ => set_nested_json_value(
-                &mut value,
-                &["ui", "active_left_panel"],
-                serde_json::Value::Null,
-            ),
-        }
-        match &settings.ui_active_right_panel {
-            Some(panel) if !panel.trim().is_empty() => {
-                set_nested_json_string(&mut value, &["ui", "active_right_panel"], panel.clone())
-            }
-            _ => set_nested_json_value(
-                &mut value,
-                &["ui", "active_right_panel"],
-                serde_json::Value::Null,
-            ),
-        }
-        set_nested_json_value(
-            &mut value,
-            &["ui", "left_panel_collapsed"],
-            serde_json::Value::Bool(settings.ui_left_panel_collapsed),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "right_panel_collapsed"],
-            serde_json::Value::Bool(settings.ui_right_panel_collapsed),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "activity_bar_layout", "left_top"],
-            string_vec_json_value(&settings.ui_activity_bar_left_top, 32),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "activity_bar_layout", "left_bottom"],
-            string_vec_json_value(&settings.ui_activity_bar_left_bottom, 32),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "activity_bar_layout", "right_top"],
-            string_vec_json_value(&settings.ui_activity_bar_right_top, 32),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "activity_bar_layout", "right_bottom"],
-            string_vec_json_value(&settings.ui_activity_bar_right_bottom, 32),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "activity_bar_layout", "show_labels"],
-            serde_json::Value::Bool(settings.ui_activity_bar_show_labels),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "panel_multi_open"],
-            serde_json::Value::Bool(settings.ui_panel_multi_open),
-        );
-        // Keep appearance key for Tauri compatibility.
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "panel_multi_open"],
-            serde_json::Value::Bool(settings.ui_panel_multi_open),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "left_open_panels"],
-            string_vec_json_value(&settings.ui_left_open_panels, 32),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "right_open_panels"],
-            string_vec_json_value(&settings.ui_right_open_panels, 32),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "panel_stack_sizes"],
-            u32_map_json_value(&settings.ui_panel_stack_sizes),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["ui", "saved_connections_sort_mode"],
-            normalize_saved_connections_sort_mode(&settings.ui_saved_connections_sort_mode),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_appearance_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_string(&mut value, &["appearance", "theme"], settings.theme.clone());
-        match settings
-            .background_image_path
-            .as_deref()
-            .map(str::trim)
-            .filter(|s| !s.is_empty())
-        {
-            Some(path) => set_nested_json_string(
-                &mut value,
-                &["appearance", "background_image_path"],
-                path.to_string(),
-            ),
-            None => set_nested_json_value(
-                &mut value,
-                &["appearance", "background_image_path"],
-                serde_json::Value::Null,
-            ),
-        }
-        set_nested_json_string(
-            &mut value,
-            &["appearance", "background_image_fit"],
-            settings.background_image_fit.clone(),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "background_image_opacity"],
-            serde_json::Value::from(settings.background_image_opacity as f64 / 100.0),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "background_opacity"],
-            serde_json::Value::from(settings.background_content_opacity as f64 / 100.0),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["appearance", "font_family"],
-            settings.terminal_font_family.clone(),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "font_size"],
-            serde_json::Value::from(settings.terminal_font_size),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["appearance", "cursor_style"],
-            match settings.cursor_style.as_str() {
-                "underline" | "bar" => settings.cursor_style.clone(),
-                _ => "block".to_string(),
-            },
-        );
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "cursor_blink"],
-            serde_json::Value::from(settings.cursor_blink),
-        );
-        match settings
-            .terminal_theme
-            .as_deref()
-            .map(str::trim)
-            .filter(|s| !s.is_empty())
-        {
-            Some(theme) => set_nested_json_string(
-                &mut value,
-                &["appearance", "terminal_theme"],
-                theme.to_string(),
-            ),
-            None => set_nested_json_value(
-                &mut value,
-                &["appearance", "terminal_theme"],
-                serde_json::Value::Null,
-            ),
-        }
-        let contrast = match settings.minimum_contrast_ratio.as_str() {
-            "3" => 3.0,
-            "4.5" => 4.5,
-            "7" => 7.0,
-            "21" => 21.0,
-            _ => 1.0,
-        };
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "minimum_contrast_ratio"],
-            serde_json::Value::from(contrast),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["appearance", "ui_font_family"],
-            if settings.ui_font_family.trim().is_empty() {
-                "Inter".to_string()
-            } else {
-                settings.ui_font_family.clone()
-            },
-        );
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "ui_font_size"],
-            serde_json::Value::from(settings.ui_font_size.clamp(12, 24)),
-        );
-        let font_weight = match settings.terminal_font_weight {
-            300 | 400 | 500 | 600 | 700 | 800 => settings.terminal_font_weight,
-            _ => 400,
-        };
-        let font_weight_bold = match settings.terminal_font_weight_bold {
-            300 | 400 | 500 | 600 | 700 | 800 => settings.terminal_font_weight_bold,
-            _ => 700,
-        };
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "font_weight"],
-            serde_json::Value::from(font_weight),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["appearance", "font_weight_bold"],
-            serde_json::Value::from(font_weight_bold),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["terminal", "x11_display"],
-            settings.x11_display.clone(),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_terminal_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_string(
-            &mut value,
-            &["terminal", "x11_display"],
-            settings.x11_display.clone(),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "scrollback_lines"],
-            serde_json::Value::from(settings.terminal_scrollback_lines.clamp(100, 100_000)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "keep_alive_interval"],
-            serde_json::Value::from(settings.terminal_keep_alive_interval.min(600)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "hardware_acceleration"],
-            serde_json::Value::Bool(settings.terminal_hardware_acceleration),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "show_workspace_padding"],
-            serde_json::Value::Bool(settings.terminal_show_workspace_padding),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "show_line_numbers"],
-            serde_json::Value::Bool(settings.terminal_show_line_numbers),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "show_timestamps"],
-            serde_json::Value::Bool(settings.terminal_show_timestamps),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "show_timestamp_milliseconds"],
-            serde_json::Value::Bool(settings.terminal_show_timestamp_milliseconds),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "show_multi_line_paste_dialog"],
-            serde_json::Value::Bool(settings.terminal_show_multi_line_paste_dialog),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "paste_image_as_path"],
-            serde_json::Value::Bool(settings.terminal_paste_image_as_path),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "low_latency_mode"],
-            serde_json::Value::Bool(settings.terminal_low_latency_mode),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "action_links_enabled"],
-            serde_json::Value::Bool(settings.terminal_action_links_enabled),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["terminal", "action_links_matchers"],
-            serde_json::json!({
-                "ipv4": settings.terminal_action_links_matchers.ipv4,
-                "archive": settings.terminal_action_links_matchers.archive,
-                "host_port": settings.terminal_action_links_matchers.host_port,
-            }),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["search", "custom_engines"],
-            search_engines_to_json(&settings.search_custom_engines),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "show_remote_stats"],
-            serde_json::Value::Bool(settings.ui_show_remote_stats),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "remote_stats_interval"],
-            serde_json::Value::from(settings.ui_remote_stats_interval.clamp(1, 60)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "show_process_manager"],
-            serde_json::Value::Bool(settings.ui_show_process_manager),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "process_manager_interval"],
-            serde_json::Value::from(settings.ui_process_manager_interval.clamp(3, 120)),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "show_docker_manager"],
-            serde_json::Value::Bool(settings.ui_show_docker_manager),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["ui", "docker_manager_interval"],
-            serde_json::Value::from(settings.ui_docker_manager_interval.clamp(3, 120)),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_interaction_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        let min_chars = settings
-            .interaction_command_suggestion_min_chars
-            .clamp(1, 500);
-        let max_chars = settings
-            .interaction_command_suggestion_max_chars
-            .clamp(min_chars, 500);
-        set_nested_json_value(
-            &mut value,
-            &["interaction", "copy_on_select"],
-            serde_json::Value::Bool(settings.interaction_copy_on_select),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["interaction", "right_click_paste"],
-            serde_json::Value::Bool(settings.interaction_right_click_paste),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["interaction", "command_suggestions_enabled"],
-            serde_json::Value::Bool(settings.interaction_command_suggestions_enabled),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["interaction", "command_suggestion_min_chars"],
-            serde_json::Value::from(min_chars),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["interaction", "command_suggestion_max_chars"],
-            serde_json::Value::from(max_chars),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["interaction", "word_separators"],
-            settings.interaction_word_separators.clone(),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["interaction", "duplicate_session_command_delay_ms"],
-            serde_json::Value::from(
-                settings
-                    .interaction_duplicate_session_command_delay_ms
-                    .min(60_000),
-            ),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["interaction", "alt_as_meta"],
-            serde_json::Value::Bool(settings.interaction_alt_as_meta),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["interaction", "mac_ime_compatibility"],
-            serde_json::Value::Bool(settings.interaction_mac_ime_compatibility),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["interaction", "tab_double_click_action"],
-            normalize_tab_mouse_action(&settings.interaction_tab_double_click_action),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["interaction", "tab_middle_click_action"],
-            normalize_tab_mouse_action(&settings.interaction_tab_middle_click_action),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["interaction", "tab_right_click_action"],
-            normalize_tab_mouse_action(&settings.interaction_tab_right_click_action),
-        );
-        set_nested_json_string(
-            &mut value,
-            &["interaction", "default_encoding"],
-            normalize_interaction_encoding(&settings.interaction_default_encoding),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_general_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_value(
-            &mut value,
-            &["general", "startup_restore"],
-            serde_json::Value::Bool(settings.startup_restore),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["general", "startup_restore_window_layout"],
-            serde_json::Value::Bool(settings.startup_restore_window_layout),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["general", "minimize_to_tray"],
-            serde_json::Value::Bool(settings.minimize_to_tray),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["general", "confirm_on_close"],
-            serde_json::Value::Bool(settings.confirm_on_close),
-        );
-        // UI language lives under ui.language (Tauri UiConfig.language).
-        let language = match settings.language.as_str() {
-            "zh-CN" | "zh" => "zh-CN",
-            "zh-TW" => "zh-TW",
-            "ja" => "ja",
-            _ => "en",
-        };
-        set_nested_json_string(&mut value, &["ui", "language"], language.to_string());
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_diagnostics_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        let level = match settings.diagnostics_level.as_str() {
-            "warn" | "debug" => settings.diagnostics_level.as_str(),
-            _ => "info",
-        };
-        let retention = match settings.diagnostics_retention_days {
-            3 | 7 | 14 | 30 => settings.diagnostics_retention_days,
-            _ => 7,
-        };
-        set_nested_json_string(&mut value, &["diagnostics", "level"], level.to_string());
-        set_nested_json_value(
-            &mut value,
-            &["diagnostics", "retention_days"],
-            serde_json::Value::from(retention),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn load_open_tabs(&self) -> Result<Vec<crate::models::RestorableOpenTab>, StorageError> {
-        let value = self.load_settings_value()?;
-        let Some(raw) = json_path(&value, &["ui", "open_tabs"]) else {
-            return Ok(Vec::new());
-        };
-        if raw.is_null() {
-            return Ok(Vec::new());
-        }
-        match serde_json::from_value::<Vec<crate::models::RestorableOpenTab>>(raw.clone()) {
-            Ok(tabs) => Ok(tabs),
-            Err(_) => Ok(Vec::new()),
-        }
-    }
-
-    pub fn save_open_tabs(
-        &self,
-        tabs: &[crate::models::RestorableOpenTab],
-    ) -> Result<(), StorageError> {
-        let mut value = self.load_settings_value()?;
-        let encoded = serde_json::to_value(tabs)?;
-        set_nested_json_value(&mut value, &["ui", "open_tabs"], encoded);
-        self.save_settings_value(&value)?;
-        Ok(())
-    }
-
-    pub fn load_terminal_window_layout(
-        &self,
-    ) -> Result<Option<crate::models::RestorableTerminalWindowNode>, StorageError> {
-        let value = self.load_settings_value()?;
-        let Some(raw) = json_path(&value, &["ui", "terminal_window_layout"]) else {
-            return Ok(None);
-        };
-        if raw.is_null() {
-            return Ok(None);
-        }
-        match serde_json::from_value(raw.clone()) {
-            Ok(node) => Ok(Some(node)),
-            Err(_) => Ok(None),
-        }
-    }
-
-    pub fn save_terminal_window_layout(
-        &self,
-        layout: Option<&crate::models::RestorableTerminalWindowNode>,
-    ) -> Result<(), StorageError> {
-        let mut value = self.load_settings_value()?;
-        let encoded = match layout {
-            Some(node) => serde_json::to_value(node)?,
-            None => serde_json::Value::Null,
-        };
-        set_nested_json_value(&mut value, &["ui", "terminal_window_layout"], encoded);
-        self.save_settings_value(&value)?;
-        Ok(())
-    }
-
-    pub fn load_workspace_pane_layout(
-        &self,
-    ) -> Result<Option<crate::models::RestorableWorkspacePaneNode>, StorageError> {
-        let value = self.load_settings_value()?;
-        let Some(raw) = json_path(&value, &["ui", "workspace_pane_layout"]) else {
-            return Ok(None);
-        };
-        if raw.is_null() {
-            return Ok(None);
-        }
-        match serde_json::from_value(raw.clone()) {
-            Ok(node) => Ok(Some(node)),
-            Err(_) => Ok(None),
-        }
-    }
-
-    pub fn save_workspace_pane_layout(
-        &self,
-        layout: Option<&crate::models::RestorableWorkspacePaneNode>,
-    ) -> Result<(), StorageError> {
-        let mut value = self.load_settings_value()?;
-        let encoded = match layout {
-            Some(node) => serde_json::to_value(node)?,
-            None => serde_json::Value::Null,
-        };
-        set_nested_json_value(&mut value, &["ui", "workspace_pane_layout"], encoded);
-        self.save_settings_value(&value)?;
-        Ok(())
-    }
-
-    pub fn save_screen_lock_settings(
-        &self,
-        settings: &AppSettingsSummary,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        set_nested_json_value(
-            &mut value,
-            &["security", "enable_screen_lock"],
-            serde_json::Value::Bool(settings.enable_screen_lock),
-        );
-        set_nested_json_value(
-            &mut value,
-            &["security", "idle_lock_minutes"],
-            serde_json::Value::from(settings.idle_lock_minutes),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
-    pub fn save_keybindings(
-        &self,
-        keybindings: &HashMap<String, String>,
-    ) -> Result<AppSettingsSummary, StorageError> {
-        let mut value = self.load_settings_value()?;
-        let mut object = serde_json::Map::new();
-        for (id, keys) in keybindings {
-            let id = id.trim();
-            let keys = keys.trim();
-            if !id.is_empty() && !keys.is_empty() {
-                object.insert(id.to_string(), serde_json::Value::String(keys.to_string()));
-            }
-        }
-        set_nested_json_value(
-            &mut value,
-            &["keybindings"],
-            serde_json::Value::Object(object),
-        );
-        self.save_settings_value(&value)?;
-        self.load_app_settings_summary()
-    }
-
     pub fn load_translation_settings(&self) -> Result<TranslationSettings, StorageError> {
         let value = self.load_settings_value()?;
         let mut settings = value
@@ -2786,73 +1539,12 @@ fn default_settings_value() -> serde_json::Value {
     })
 }
 
-fn json_u32_map(value: &serde_json::Value, path: &[&str]) -> HashMap<String, u32> {
-    let mut map = HashMap::new();
-    let Some(object) = json_path(value, path).and_then(|value| value.as_object()) else {
-        return map;
-    };
-    for (key, raw) in object {
-        let number = raw
-            .as_u64()
-            .or_else(|| raw.as_f64().map(|value| value.round() as u64));
-        if let Some(number) = number {
-            if number > 0 {
-                map.insert(key.clone(), number.min(u32::MAX as u64) as u32);
-            }
-        }
-    }
-    map
-}
-
-fn u32_map_json_value(map: &HashMap<String, u32>) -> serde_json::Value {
-    let mut object = serde_json::Map::new();
-    for (key, value) in map {
-        if *value > 0 {
-            object.insert(key.clone(), serde_json::json!(*value));
-        }
-    }
-    serde_json::Value::Object(object)
-}
-
-fn json_optional_string(value: &serde_json::Value, path: &[&str]) -> Option<String> {
-    json_path(value, path)
-        .and_then(|value| value.as_str())
-        .map(str::trim)
-        .filter(|value| !value.is_empty())
-        .map(ToOwned::to_owned)
-}
-
-fn json_string(value: &serde_json::Value, path: &[&str], fallback: &str) -> String {
-    json_path(value, path)
-        .and_then(serde_json::Value::as_str)
-        .filter(|value| !value.is_empty())
-        .unwrap_or(fallback)
-        .to_string()
-}
-
 fn json_bool(value: &serde_json::Value, path: &[&str], fallback: bool) -> bool {
     json_path(value, path)
         .and_then(serde_json::Value::as_bool)
         .unwrap_or(fallback)
 }
 
-fn json_string_map(value: &serde_json::Value, path: &[&str]) -> HashMap<String, String> {
-    json_path(value, path)
-        .and_then(serde_json::Value::as_object)
-        .map(|object| {
-            object
-                .iter()
-                .filter_map(|(key, value)| {
-                    value
-                        .as_str()
-                        .filter(|value| !value.trim().is_empty())
-                        .map(|value| (key.clone(), value.to_string()))
-                })
-                .collect()
-        })
-        .unwrap_or_default()
-}
-
 fn json_string_vec(value: &serde_json::Value, path: &[&str], limit: usize) -> Vec<String> {
     json_path(value, path)
         .and_then(serde_json::Value::as_array)
@@ -2879,151 +1571,6 @@ fn json_string_vec(value: &serde_json::Value, path: &[&str], limit: usize) -> Ve
         .unwrap_or_default()
 }
 
-fn json_string_vec_with_default(
-    value: &serde_json::Value,
-    path: &[&str],
-    limit: usize,
-    default: fn() -> Vec<String>,
-) -> Vec<String> {
-    if json_path(value, path).is_some() {
-        json_string_vec(value, path, limit)
-    } else {
-        default()
-    }
-}
-
-fn json_string_vec_map(
-    value: &serde_json::Value,
-    path: &[&str],
-    limit_per_key: usize,
-) -> HashMap<String, Vec<String>> {
-    json_path(value, path)
-        .and_then(serde_json::Value::as_object)
-        .map(|object| {
-            object
-                .iter()
-                .filter_map(|(key, value)| {
-                    let values = value
-                        .as_array()?
-                        .iter()
-                        .filter_map(|entry| {
-                            entry
-                                .as_str()
-                                .map(str::trim)
-                                .filter(|entry| !entry.is_empty())
-                                .map(ToOwned::to_owned)
-                        })
-                        .fold(Vec::<String>::new(), |mut values, entry| {
-                            if !values.iter().any(|existing| existing == &entry) {
-                                values.push(entry);
-                            }
-                            values
-                        })
-                        .into_iter()
-                        .take(limit_per_key)
-                        .collect::<Vec<_>>();
-                    (!values.is_empty()).then(|| (key.clone(), values))
-                })
-                .collect()
-        })
-        .unwrap_or_default()
-}
-
-fn string_vec_json_value(values: &[String], limit: usize) -> serde_json::Value {
-    serde_json::Value::Array(
-        values
-            .iter()
-            .map(|value| value.trim())
-            .filter(|value| !value.is_empty())
-            .fold(Vec::<String>::new(), |mut values, value| {
-                if !values.iter().any(|existing| existing == value) {
-                    values.push(value.to_string());
-                }
-                values
-            })
-            .into_iter()
-            .take(limit)
-            .map(serde_json::Value::String)
-            .collect(),
-    )
-}
-
-fn string_vec_map_json_value(
-    map: &HashMap<String, Vec<String>>,
-    limit_per_key: usize,
-) -> serde_json::Value {
-    let object = map
-        .iter()
-        .filter_map(|(key, values)| {
-            let key = key.trim();
-            if key.is_empty() {
-                return None;
-            }
-            let values = values
-                .iter()
-                .map(|value| value.trim())
-                .filter(|value| !value.is_empty())
-                .fold(Vec::<String>::new(), |mut values, value| {
-                    if !values.iter().any(|existing| existing == value) {
-                        values.push(value.to_string());
-                    }
-                    values
-                })
-                .into_iter()
-                .take(limit_per_key)
-                .map(serde_json::Value::String)
-                .collect::<Vec<_>>();
-            (!values.is_empty()).then(|| (key.to_string(), serde_json::Value::Array(values)))
-        })
-        .collect();
-    serde_json::Value::Object(object)
-}
-
-fn json_u16(value: &serde_json::Value, path: &[&str], fallback: u16) -> u16 {
-    let Some(value) = json_path(value, path) else {
-        return fallback;
-    };
-    if let Some(number) = value.as_u64() {
-        return number.try_into().unwrap_or(fallback);
-    }
-    if let Some(number) = value.as_f64() {
-        if number.is_finite() && number >= 0.0 && number <= f64::from(u16::MAX) {
-            return number.round() as u16;
-        }
-    }
-    fallback
-}
-
-fn json_u32(value: &serde_json::Value, path: &[&str], fallback: u32) -> u32 {
-    let Some(value) = json_path(value, path) else {
-        return fallback;
-    };
-    if let Some(number) = value.as_u64() {
-        return number.try_into().unwrap_or(fallback);
-    }
-    if let Some(number) = value.as_f64() {
-        if number.is_finite() && number >= 0.0 && number <= f64::from(u32::MAX) {
-            return number.round() as u32;
-        }
-    }
-    fallback
-}
-
-fn json_u64(value: &serde_json::Value, path: &[&str], fallback: u64) -> u64 {
-    let Some(value) = json_path(value, path) else {
-        return fallback;
-    };
-    if let Some(number) = value.as_u64() {
-        return number;
-    }
-    if let Some(number) = value.as_f64() {
-        if number.is_finite() && number >= 0.0 && number <= u64::MAX as f64 {
-            return number.round() as u64;
-        }
-    }
-    fallback
-}
-
 fn json_path<'a>(value: &'a serde_json::Value, path: &[&str]) -> Option<&'a serde_json::Value> {
     let mut current = value;
     for key in path {
@@ -3032,89 +1579,6 @@ fn json_path<'a>(value: &'a serde_json::Value, path: &[&str]) -> Option<&'a serd
     Some(current)
 }
 
-fn set_nested_json_string(value: &mut serde_json::Value, path: &[&str], new_value: String) {
-    set_nested_json_value(value, path, serde_json::Value::String(new_value));
-}
-
-fn load_action_links_matchers(value: &serde_json::Value) -> crate::ActionLinksMatcherSettings {
-    let defaults = crate::ActionLinksMatcherSettings::default();
-    let Some(obj) = json_path(value, &["terminal", "action_links_matchers"]) else {
-        return defaults;
-    };
-    crate::ActionLinksMatcherSettings {
-        ipv4: obj
-            .get("ipv4")
-            .and_then(|v| v.as_bool())
-            .unwrap_or(defaults.ipv4),
-        archive: obj
-            .get("archive")
-            .and_then(|v| v.as_bool())
-            .unwrap_or(defaults.archive),
-        host_port: obj
-            .get("host_port")
-            .and_then(|v| v.as_bool())
-            .unwrap_or(defaults.host_port),
-    }
-}
-
-fn load_search_engines(value: &serde_json::Value) -> Vec<SearchEngineConfig> {
-    let Some(arr) = json_path(value, &["search", "custom_engines"]).and_then(|v| v.as_array())
-    else {
-        return default_search_engines();
-    };
-    let mut engines = Vec::new();
-    for item in arr {
-        if !item.is_object() {
-            continue;
-        }
-        let name = item
-            .get("name")
-            .and_then(|v| v.as_str())
-            .unwrap_or("")
-            .trim()
-            .to_string();
-        let url_template = item
-            .get("url_template")
-            .and_then(|v| v.as_str())
-            .unwrap_or("")
-            .trim()
-            .to_string();
-        let show_in_menu = item
-            .get("show_in_menu")
-            .and_then(|v| v.as_bool())
-            .unwrap_or(true);
-        let icon = item
-            .get("icon")
-            .and_then(|v| v.as_str())
-            .map(str::trim)
-            .filter(|s| !s.is_empty())
-            .map(ToString::to_string);
-        engines.push(SearchEngineConfig {
-            name,
-            url_template,
-            icon,
-            show_in_menu,
-        });
-    }
-    engines
-}
-
-fn search_engines_to_json(engines: &[SearchEngineConfig]) -> serde_json::Value {
-    serde_json::Value::Array(
-        engines
-            .iter()
-            .map(|engine| {
-                serde_json::json!({
-                    "name": engine.name,
-                    "url_template": engine.url_template,
-                    "icon": engine.icon,
-                    "show_in_menu": engine.show_in_menu,
-                })
-            })
-            .collect(),
-    )
-}
-
 fn set_nested_json_value(
     value: &mut serde_json::Value,
     path: &[&str],
@@ -3135,112 +1599,6 @@ fn set_nested_json_value(
     }
 }
 
-fn normalize_host_key_policy(policy: &str) -> String {
-    match policy {
-        "strict" | "accept" | "prompt" => policy.to_string(),
-        _ => "prompt".to_string(),
-    }
-}
-
-fn normalize_transfer_duplicate_strategy(strategy: &str) -> String {
-    match strategy {
-        "ask" | "overwrite" | "skip" | "rename" => strategy.to_string(),
-        _ => "ask".to_string(),
-    }
-}
-
-fn normalize_transfer_editor_type(editor_type: &str) -> String {
-    match editor_type {
-        "external" | "internal" => editor_type.to_string(),
-        _ => "external".to_string(),
-    }
-}
-
-fn normalize_transfer_file_permissions(value: &str) -> String {
-    let trimmed = value
-        .trim()
-        .trim_start_matches("0o")
-        .trim_start_matches('0');
-    let normalized = if trimmed.is_empty() { "0" } else { trimmed };
-    if (3..=4).contains(&normalized.len()) && normalized.chars().all(|ch| matches!(ch, '0'..='7')) {
-        normalized.to_string()
-    } else {
-        "644".to_string()
-    }
-}
-
-fn default_activity_left_top() -> Vec<String> {
-    vec![
-        "fileExplorer".to_string(),
-        "network".to_string(),
-        "securityAuth".to_string(),
-    ]
-}
-
-fn default_activity_left_bottom() -> Vec<String> {
-    vec!["syncBackupHistory".to_string(), "settings".to_string()]
-}
-
-fn default_activity_right_top() -> Vec<String> {
-    vec![
-        "savedConnections".to_string(),
-        "aiAssistant".to_string(),
-        "activeSessions".to_string(),
-        "commandHistory".to_string(),
-        "resourceMonitor".to_string(),
-        "processManager".to_string(),
-        "dockerManager".to_string(),
-    ]
-}
-
-fn default_activity_right_bottom() -> Vec<String> {
-    vec![
-        "quickCmdBar".to_string(),
-        "serialSend".to_string(),
-        "recording".to_string(),
-        "lock".to_string(),
-    ]
-}
-
-fn normalize_quick_cmd_view_mode(value: &str) -> String {
-    match value.trim() {
-        "list" | "compact" | "tile" => value.trim().to_string(),
-        _ => "tile".to_string(),
-    }
-}
-
-fn normalize_quick_cmd_sort_mode(value: &str) -> String {
-    match value.trim() {
-        "created" | "name" | "useCount" => value.trim().to_string(),
-        _ => "created".to_string(),
-    }
-}
-
-fn normalize_saved_connections_sort_mode(value: &str) -> String {
-    match value.trim() {
-        "name-asc" | "name-desc" => value.trim().to_string(),
-        _ => "default".to_string(),
-    }
-}
-
-fn normalize_tab_mouse_action(action: &str) -> String {
-    match action {
-        "none" | "rename_tab" | "copy_tab_name" | "copy_server_ip" | "duplicate_session"
-        | "multiplex_ssh" | "reconnect_session" | "disconnect_session" | "close_tab" => {
-            action.to_string()
-        }
-        _ => "none".to_string(),
-    }
-}
-
-fn normalize_interaction_encoding(encoding: &str) -> String {
-    if encoding.eq_ignore_ascii_case("gbk") {
-        "GBK".to_string()
-    } else {
-        "UTF-8".to_string()
-    }
-}
-
 fn padded_i64(value: i64) -> String {
     let shifted = i128::from(value) - i128::from(i64::MIN);
     format!("{shifted:020}")
@@ -3305,7 +1663,8 @@ fn current_time_ms() -> u64 {
 mod tests {
     use super::*;
     use crate::{
-        AiExecutionProfile, CommandHistoryEntry, ConnectionAuth, ConnectionType, OtpEntry, SshKey,
+        AiExecutionProfile, CommandHistoryEntry, ConnectionAuth, ConnectionType, OtpEntry,
+        SearchEngineConfig, SshKey,
     };
     use aes_gcm::{Aes256Gcm, Key, KeyInit, aead::Aead};
     use base64::{Engine, engine::general_purpose::STANDARD as B64};
diff --git a/crates/nyaterm-core/src/storage/app_settings.rs b/crates/nyaterm-core/src/storage/app_settings.rs
new file mode 100644
index 000000000..7c9f0e9ba
--- /dev/null
+++ b/crates/nyaterm-core/src/storage/app_settings.rs
@@ -0,0 +1,1658 @@
+//! Application settings document persistence.
+//!
+//! Split out of `storage.rs` by domain. Every method here reads or writes the
+//! single app settings document and returns the refreshed
+//! [`AppSettingsSummary`]; document keys, field names and defaults are
+//! unchanged.
+
+use std::collections::HashMap;
+
+use super::{
+    ConnectionStore, LEGACY_TEXT_MASTER_KEY, META_MASTER_KEY, META_TABLE, SETTINGS_DEFAULT,
+    SETTINGS_TABLE, StorageError, TEXT_DOCS_TABLE, json_bool, json_path, json_string_vec,
+    set_nested_json_value, write_json_in_txn,
+};
+use crate::{AppSettingsSummary, CredentialCrypto, SearchEngineConfig, default_search_engines};
+
+impl ConnectionStore {
+    pub fn load_app_settings_summary(&self) -> Result<AppSettingsSummary, StorageError> {
+        let value = self.load_settings_value()?;
+        Ok(AppSettingsSummary {
+            theme: json_string(&value, &["appearance", "theme"], "github-dark"),
+            background_image_path: json_path(&value, &["appearance", "background_image_path"])
+                .and_then(|v| v.as_str())
+                .map(str::trim)
+                .filter(|s| !s.is_empty())
+                .map(|s| s.to_string()),
+            background_image_fit: json_string(
+                &value,
+                &["appearance", "background_image_fit"],
+                "cover",
+            ),
+            background_image_opacity: {
+                let raw = json_path(&value, &["appearance", "background_image_opacity"]);
+                let pct = raw
+                    .and_then(|v| v.as_f64())
+                    .map(|v| {
+                        // Accept both 0..1 float (Tauri) and 0..100 percent.
+                        if v <= 1.0 {
+                            (v * 100.0).round() as u8
+                        } else {
+                            v.round() as u8
+                        }
+                    })
+                    .unwrap_or(45)
+                    .clamp(0, 100);
+                pct
+            },
+            background_content_opacity: {
+                let raw = json_path(&value, &["appearance", "background_opacity"]);
+                let pct = raw
+                    .and_then(|v| v.as_f64())
+                    .map(|v| {
+                        if v <= 1.0 {
+                            (v * 100.0).round() as u8
+                        } else {
+                            v.round() as u8
+                        }
+                    })
+                    .unwrap_or(82)
+                    .clamp(0, 100);
+                pct
+            },
+            // Tauri UiConfig.language (not translation.target_language).
+            language: json_string(&value, &["ui", "language"], "en"),
+            terminal_font_family: json_string(
+                &value,
+                &["appearance", "font_family"],
+                "JetBrains Mono",
+            ),
+            terminal_font_size: json_u16(&value, &["appearance", "font_size"], 16),
+            cursor_style: {
+                let raw = json_string(&value, &["appearance", "cursor_style"], "block");
+                match raw.as_str() {
+                    "underline" | "bar" | "block" => raw,
+                    _ => "block".to_string(),
+                }
+            },
+            cursor_blink: json_bool(&value, &["appearance", "cursor_blink"], true),
+            terminal_theme: {
+                let raw = json_path(&value, &["appearance", "terminal_theme"])
+                    .and_then(|v| v.as_str())
+                    .map(str::trim)
+                    .filter(|s| !s.is_empty())
+                    .map(|s| s.to_string());
+                raw
+            },
+            minimum_contrast_ratio: {
+                let raw = json_path(&value, &["appearance", "minimum_contrast_ratio"]);
+                let num = raw.and_then(|v| {
+                    v.as_f64()
+                        .or_else(|| v.as_str().and_then(|s| s.parse::<f64>().ok()))
+                });
+                match num {
+                    Some(1.0) => "1".to_string(),
+                    Some(3.0) => "3".to_string(),
+                    Some(4.5) => "4.5".to_string(),
+                    Some(7.0) => "7".to_string(),
+                    Some(21.0) => "21".to_string(),
+                    _ => "1".to_string(),
+                }
+            },
+            ui_font_family: json_string(&value, &["appearance", "ui_font_family"], "Inter"),
+            ui_font_size: json_u16(&value, &["appearance", "ui_font_size"], 16).clamp(12, 24),
+            terminal_font_weight: {
+                let w = json_u16(&value, &["appearance", "font_weight"], 400);
+                match w {
+                    300 | 400 | 500 | 600 | 700 | 800 => w,
+                    _ => 400,
+                }
+            },
+            terminal_font_weight_bold: {
+                let w = json_u16(&value, &["appearance", "font_weight_bold"], 700);
+                match w {
+                    300 | 400 | 500 | 600 | 700 | 800 => w,
+                    _ => 700,
+                }
+            },
+            x11_display: json_string(&value, &["terminal", "x11_display"], ""),
+            terminal_scrollback_lines: json_u32(&value, &["terminal", "scrollback_lines"], 5000)
+                .clamp(100, 100_000),
+            terminal_keep_alive_interval: json_u32(
+                &value,
+                &["terminal", "keep_alive_interval"],
+                30,
+            )
+            .min(600),
+            terminal_hardware_acceleration: json_bool(
+                &value,
+                &["terminal", "hardware_acceleration"],
+                true,
+            ),
+            terminal_show_workspace_padding: json_bool(
+                &value,
+                &["terminal", "show_workspace_padding"],
+                false,
+            ),
+            terminal_show_line_numbers: json_bool(
+                &value,
+                &["terminal", "show_line_numbers"],
+                false,
+            ),
+            terminal_show_timestamps: json_bool(&value, &["terminal", "show_timestamps"], false),
+            terminal_show_timestamp_milliseconds: json_bool(
+                &value,
+                &["terminal", "show_timestamp_milliseconds"],
+                false,
+            ),
+            terminal_show_multi_line_paste_dialog: json_bool(
+                &value,
+                &["terminal", "show_multi_line_paste_dialog"],
+                true,
+            ),
+            terminal_paste_image_as_path: json_bool(
+                &value,
+                &["terminal", "paste_image_as_path"],
+                true,
+            ),
+            terminal_low_latency_mode: json_bool(&value, &["terminal", "low_latency_mode"], false),
+            terminal_action_links_enabled: json_bool(
+                &value,
+                &["terminal", "action_links_enabled"],
+                false,
+            ),
+            terminal_action_links_matchers: load_action_links_matchers(&value),
+            search_custom_engines: load_search_engines(&value),
+            ui_show_remote_stats: json_bool(&value, &["ui", "show_remote_stats"], true),
+            ui_remote_stats_interval: json_u32(&value, &["ui", "remote_stats_interval"], 3)
+                .clamp(1, 60),
+            ui_show_process_manager: json_bool(&value, &["ui", "show_process_manager"], true),
+            ui_process_manager_interval: json_u32(&value, &["ui", "process_manager_interval"], 5)
+                .clamp(3, 120),
+            ui_show_docker_manager: json_bool(&value, &["ui", "show_docker_manager"], true),
+            ui_docker_manager_interval: json_u32(&value, &["ui", "docker_manager_interval"], 10)
+                .clamp(3, 120),
+            ui_quick_cmd_view_mode: normalize_quick_cmd_view_mode(&json_string(
+                &value,
+                &["ui", "quick_cmd_view_mode"],
+                "tile",
+            )),
+            ui_quick_cmd_sort_mode: normalize_quick_cmd_sort_mode(&json_string(
+                &value,
+                &["ui", "quick_cmd_sort_mode"],
+                "created",
+            )),
+            ui_saved_connections_sort_mode: normalize_saved_connections_sort_mode(&json_string(
+                &value,
+                &["ui", "saved_connections_sort_mode"],
+                "default",
+            )),
+            ui_file_explorer_auto_sync_cwd_connection_ids: json_string_vec(
+                &value,
+                &["ui", "file_explorer_auto_sync_cwd_connection_ids"],
+                256,
+            ),
+            ui_file_explorer_favorite_dirs_by_connection_id: json_string_vec_map(
+                &value,
+                &["ui", "file_explorer_favorite_dirs_by_connection_id"],
+                12,
+            ),
+            ui_left_panel_width: json_u32(&value, &["ui", "left_width"], 256).clamp(160, 720),
+            ui_right_panel_width: json_u32(&value, &["ui", "right_width"], 288).clamp(200, 720),
+            ui_transfer_height: json_u32(&value, &["ui", "transfer_height"], 180).clamp(60, 600),
+            ui_quick_cmd_height: json_u32(&value, &["ui", "quick_cmd_height"], 180).clamp(36, 520),
+            ui_quick_cmd_visible: json_bool(&value, &["ui", "show_quick_cmd_bar"], true),
+            ui_serial_send_height: json_u32(&value, &["ui", "serial_send_height"], 180)
+                .clamp(60, 520),
+            ui_serial_send_visible: json_bool(&value, &["ui", "show_serial_send_panel"], false),
+            ui_active_left_panel: json_optional_string(&value, &["ui", "active_left_panel"]),
+            ui_active_right_panel: json_optional_string(&value, &["ui", "active_right_panel"]),
+            ui_left_panel_collapsed: json_bool(&value, &["ui", "left_panel_collapsed"], false),
+            ui_right_panel_collapsed: json_bool(&value, &["ui", "right_panel_collapsed"], false),
+            ui_activity_bar_left_top: {
+                json_string_vec_with_default(
+                    &value,
+                    &["ui", "activity_bar_layout", "left_top"],
+                    32,
+                    default_activity_left_top,
+                )
+            },
+            ui_activity_bar_left_bottom: {
+                json_string_vec_with_default(
+                    &value,
+                    &["ui", "activity_bar_layout", "left_bottom"],
+                    32,
+                    default_activity_left_bottom,
+                )
+            },
+            ui_activity_bar_right_top: {
+                json_string_vec_with_default(
+                    &value,
+                    &["ui", "activity_bar_layout", "right_top"],
+                    32,
+                    default_activity_right_top,
+                )
+            },
+            ui_activity_bar_right_bottom: {
+                json_string_vec_with_default(
+                    &value,
+                    &["ui", "activity_bar_layout", "right_bottom"],
+                    32,
+                    default_activity_right_bottom,
+                )
+            },
+            ui_activity_bar_show_labels: json_bool(
+                &value,
+                &["ui", "activity_bar_layout", "show_labels"],
+                false,
+            ),
+            ui_panel_multi_open: json_bool(&value, &["appearance", "panel_multi_open"], false)
+                || json_bool(&value, &["ui", "panel_multi_open"], false),
+            ui_left_open_panels: json_string_vec(&value, &["ui", "left_open_panels"], 32),
+            ui_right_open_panels: json_string_vec(&value, &["ui", "right_open_panels"], 32),
+            ui_panel_stack_sizes: json_u32_map(&value, &["ui", "panel_stack_sizes"]),
+            interaction_copy_on_select: json_bool(
+                &value,
+                &["interaction", "copy_on_select"],
+                false,
+            ),
+            interaction_right_click_paste: json_bool(
+                &value,
+                &["interaction", "right_click_paste"],
+                false,
+            ),
+            interaction_command_suggestions_enabled: json_bool(
+                &value,
+                &["interaction", "command_suggestions_enabled"],
+                true,
+            ),
+            interaction_command_suggestion_min_chars: json_u32(
+                &value,
+                &["interaction", "command_suggestion_min_chars"],
+                2,
+            )
+            .clamp(1, 500),
+            interaction_command_suggestion_max_chars: json_u32(
+                &value,
+                &["interaction", "command_suggestion_max_chars"],
+                64,
+            )
+            .clamp(1, 500),
+            interaction_word_separators: json_string(
+                &value,
+                &["interaction", "word_separators"],
+                " \t\r\n\"'`~!@#$%^&*()-=+[{]}\\|;:,<.>/?",
+            ),
+            interaction_duplicate_session_command_delay_ms: json_u32(
+                &value,
+                &["interaction", "duplicate_session_command_delay_ms"],
+                1000,
+            )
+            .min(60_000),
+            interaction_alt_as_meta: json_bool(&value, &["interaction", "alt_as_meta"], false),
+            interaction_mac_ime_compatibility: json_bool(
+                &value,
+                &["interaction", "mac_ime_compatibility"],
+                true,
+            ),
+            interaction_tab_double_click_action: normalize_tab_mouse_action(&json_string(
+                &value,
+                &["interaction", "tab_double_click_action"],
+                "disconnect_session",
+            )),
+            interaction_tab_middle_click_action: normalize_tab_mouse_action(&json_string(
+                &value,
+                &["interaction", "tab_middle_click_action"],
+                "rename_tab",
+            )),
+            interaction_tab_right_click_action: normalize_tab_mouse_action(&json_string(
+                &value,
+                &["interaction", "tab_right_click_action"],
+                "none",
+            )),
+            interaction_default_encoding: normalize_interaction_encoding(&json_string(
+                &value,
+                &["interaction", "default_encoding"],
+                "UTF-8",
+            )),
+            host_key_policy: normalize_host_key_policy(&json_string(
+                &value,
+                &["security", "host_key_policy"],
+                "prompt",
+            )),
+            transfer_download_path: json_string(&value, &["transfer", "download_path"], ""),
+            transfer_ask_save_location: json_bool(
+                &value,
+                &["transfer", "ask_save_location"],
+                false,
+            ),
+            transfer_duplicate_strategy: normalize_transfer_duplicate_strategy(&json_string(
+                &value,
+                &["transfer", "duplicate_strategy"],
+                "ask",
+            )),
+            transfer_editor_type: normalize_transfer_editor_type(&json_string(
+                &value,
+                &["transfer", "editor_type"],
+                "external",
+            )),
+            transfer_default_editor: json_string(&value, &["transfer", "default_editor"], ""),
+            transfer_download_threads: json_u32(&value, &["transfer", "download_threads"], 3)
+                .clamp(1, 10),
+            transfer_upload_threads: json_u32(&value, &["transfer", "upload_threads"], 3)
+                .clamp(1, 10),
+            transfer_max_retries: json_u32(&value, &["transfer", "max_transfer_retries"], 2)
+                .min(10),
+            transfer_buffer_size: json_u32(&value, &["transfer", "transfer_buffer_size"], 32)
+                .clamp(8, 256),
+            transfer_default_file_permissions: normalize_transfer_file_permissions(&json_string(
+                &value,
+                &["transfer", "default_file_permissions"],
+                "644",
+            )),
+            transfer_preserve_timestamps: json_bool(
+                &value,
+                &["transfer", "preserve_timestamps"],
+                true,
+            ),
+            transfer_resume_broken_transfer: json_bool(
+                &value,
+                &["transfer", "resume_broken_transfer"],
+                true,
+            ),
+            recording_path: json_string(&value, &["transfer", "recording_path"], ""),
+            recording_auto_start: json_bool(&value, &["transfer", "recording_auto_start"], false),
+            recording_include_io_labels: json_bool(
+                &value,
+                &["transfer", "recording_include_io_labels"],
+                true,
+            ),
+            recording_include_timestamps: json_bool(
+                &value,
+                &["transfer", "recording_include_timestamps"],
+                true,
+            ),
+            recording_memory_limit_bytes: json_u64(
+                &value,
+                &["transfer", "recording_memory_limit_bytes"],
+                5 * 1024 * 1024,
+            ),
+            diagnostics_level: {
+                let raw = json_string(&value, &["diagnostics", "level"], "info");
+                match raw.as_str() {
+                    "warn" | "debug" => raw,
+                    _ => "info".to_string(),
+                }
+            },
+            diagnostics_retention_days: {
+                let days = u32::from(json_u16(&value, &["diagnostics", "retention_days"], 7));
+                match days {
+                    3 | 7 | 14 | 30 => days,
+                    _ => 7,
+                }
+            },
+            startup_restore: json_bool(&value, &["general", "startup_restore"], false),
+            startup_restore_window_layout: json_bool(
+                &value,
+                &["general", "startup_restore_window_layout"],
+                true,
+            ),
+            minimize_to_tray: json_bool(&value, &["general", "minimize_to_tray"], false),
+            confirm_on_close: json_bool(&value, &["general", "confirm_on_close"], true),
+            enable_screen_lock: json_bool(&value, &["security", "enable_screen_lock"], false),
+            idle_lock_minutes: u32::from(json_u16(&value, &["security", "idle_lock_minutes"], 0)),
+            has_master_password: value
+                .get("security")
+                .and_then(|security| security.get("master_password"))
+                .and_then(|master_password| master_password.as_str())
+                .is_some_and(|master_password| !master_password.is_empty()),
+            keybindings: json_string_map(&value, &["keybindings"]),
+        })
+    }
+
+    pub fn verify_master_password(&self, password: &str) -> Result<bool, StorageError> {
+        let Some(token) = self.load_encrypted_master_password()? else {
+            return Ok(true);
+        };
+        let bootstrap = CredentialCrypto::new(self.portable_key_path.clone(), None);
+        let stored = bootstrap.decrypt_settings_secret(&token)?;
+        Ok(stored == password)
+    }
+
+    pub fn save_master_password(
+        &self,
+        next_password: Option<&str>,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        if next_password.is_some_and(str::is_empty) {
+            return Err(StorageError::InvalidData(
+                "Master password cannot be empty when enabled".to_string(),
+            ));
+        }
+
+        let bootstrap = CredentialCrypto::new(self.portable_key_path.clone(), None);
+        let current_password = self
+            .load_encrypted_master_password()?
+            .map(|token| bootstrap.decrypt_settings_secret(&token))
+            .transpose()?;
+        let rewrapped_master_key = self
+            .load_master_key_token()?
+            .map(|token| {
+                CredentialCrypto::new(self.portable_key_path.clone(), current_password.clone())
+                    .rewrap_master_key_token(&token, next_password)
+            })
+            .transpose()?;
+
+        let mut value = self.load_settings_value()?;
+        let encoded_password = next_password
+            .map(|password| bootstrap.encrypt_settings_secret(password))
+            .transpose()?;
+        set_nested_json_value(
+            &mut value,
+            &["security", "master_password"],
+            encoded_password
+                .map(serde_json::Value::String)
+                .unwrap_or(serde_json::Value::Null),
+        );
+
+        let txn = self.db.begin_write()?;
+        write_json_in_txn(&txn, SETTINGS_TABLE, SETTINGS_DEFAULT, &value)?;
+        if let Some(token) = rewrapped_master_key.as_deref() {
+            txn.open_table(META_TABLE)?.insert(META_MASTER_KEY, token)?;
+            txn.open_table(TEXT_DOCS_TABLE)?
+                .insert(LEGACY_TEXT_MASTER_KEY, token)?;
+        }
+        txn.commit()?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_host_key_policy(&self, policy: &str) -> Result<AppSettingsSummary, StorageError> {
+        let policy = normalize_host_key_policy(policy);
+        let mut value = self.load_settings_value()?;
+        set_nested_json_string(&mut value, &["security", "host_key_policy"], policy);
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_recording_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_string(
+            &mut value,
+            &["transfer", "recording_path"],
+            settings.recording_path.clone(),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "recording_auto_start"],
+            serde_json::Value::Bool(settings.recording_auto_start),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "recording_include_io_labels"],
+            serde_json::Value::Bool(settings.recording_include_io_labels),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "recording_include_timestamps"],
+            serde_json::Value::Bool(settings.recording_include_timestamps),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "recording_memory_limit_bytes"],
+            serde_json::Value::from(settings.recording_memory_limit_bytes),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_transfer_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_string(
+            &mut value,
+            &["transfer", "download_path"],
+            settings.transfer_download_path.clone(),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "ask_save_location"],
+            serde_json::Value::Bool(settings.transfer_ask_save_location),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["transfer", "duplicate_strategy"],
+            normalize_transfer_duplicate_strategy(&settings.transfer_duplicate_strategy),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["transfer", "editor_type"],
+            normalize_transfer_editor_type(&settings.transfer_editor_type),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["transfer", "default_editor"],
+            settings.transfer_default_editor.clone(),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "download_threads"],
+            serde_json::Value::from(settings.transfer_download_threads.clamp(1, 10)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "upload_threads"],
+            serde_json::Value::from(settings.transfer_upload_threads.clamp(1, 10)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "max_transfer_retries"],
+            serde_json::Value::from(settings.transfer_max_retries.min(10)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "transfer_buffer_size"],
+            serde_json::Value::from(settings.transfer_buffer_size.clamp(8, 256)),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["transfer", "default_file_permissions"],
+            normalize_transfer_file_permissions(&settings.transfer_default_file_permissions),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "preserve_timestamps"],
+            serde_json::Value::Bool(settings.transfer_preserve_timestamps),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["transfer", "resume_broken_transfer"],
+            serde_json::Value::Bool(settings.transfer_resume_broken_transfer),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_file_explorer_favorite_dirs(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_value(
+            &mut value,
+            &["ui", "file_explorer_auto_sync_cwd_connection_ids"],
+            string_vec_json_value(&settings.ui_file_explorer_auto_sync_cwd_connection_ids, 256),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "file_explorer_favorite_dirs_by_connection_id"],
+            string_vec_map_json_value(
+                &settings.ui_file_explorer_favorite_dirs_by_connection_id,
+                12,
+            ),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_quick_command_ui_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_string(
+            &mut value,
+            &["ui", "quick_cmd_view_mode"],
+            normalize_quick_cmd_view_mode(&settings.ui_quick_cmd_view_mode),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["ui", "quick_cmd_sort_mode"],
+            normalize_quick_cmd_sort_mode(&settings.ui_quick_cmd_sort_mode),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_ui_layout_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_value(
+            &mut value,
+            &["ui", "left_width"],
+            serde_json::Value::from(settings.ui_left_panel_width.clamp(160, 720)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "right_width"],
+            serde_json::Value::from(settings.ui_right_panel_width.clamp(200, 720)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "transfer_height"],
+            serde_json::Value::from(settings.ui_transfer_height.clamp(60, 600)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "quick_cmd_height"],
+            serde_json::Value::from(settings.ui_quick_cmd_height.clamp(36, 520)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "show_quick_cmd_bar"],
+            serde_json::Value::Bool(settings.ui_quick_cmd_visible),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "serial_send_height"],
+            serde_json::Value::from(settings.ui_serial_send_height.clamp(60, 520)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "show_serial_send_panel"],
+            serde_json::Value::Bool(settings.ui_serial_send_visible),
+        );
+        match &settings.ui_active_left_panel {
+            Some(panel) if !panel.trim().is_empty() => {
+                set_nested_json_string(&mut value, &["ui", "active_left_panel"], panel.clone())
+            }
+            _ => set_nested_json_value(
+                &mut value,
+                &["ui", "active_left_panel"],
+                serde_json::Value::Null,
+            ),
+        }
+        match &settings.ui_active_right_panel {
+            Some(panel) if !panel.trim().is_empty() => {
+                set_nested_json_string(&mut value, &["ui", "active_right_panel"], panel.clone())
+            }
+            _ => set_nested_json_value(
+                &mut value,
+                &["ui", "active_right_panel"],
+                serde_json::Value::Null,
+            ),
+        }
+        set_nested_json_value(
+            &mut value,
+            &["ui", "left_panel_collapsed"],
+            serde_json::Value::Bool(settings.ui_left_panel_collapsed),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "right_panel_collapsed"],
+            serde_json::Value::Bool(settings.ui_right_panel_collapsed),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "activity_bar_layout", "left_top"],
+            string_vec_json_value(&settings.ui_activity_bar_left_top, 32),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "activity_bar_layout", "left_bottom"],
+            string_vec_json_value(&settings.ui_activity_bar_left_bottom, 32),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "activity_bar_layout", "right_top"],
+            string_vec_json_value(&settings.ui_activity_bar_right_top, 32),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "activity_bar_layout", "right_bottom"],
+            string_vec_json_value(&settings.ui_activity_bar_right_bottom, 32),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "activity_bar_layout", "show_labels"],
+            serde_json::Value::Bool(settings.ui_activity_bar_show_labels),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "panel_multi_open"],
+            serde_json::Value::Bool(settings.ui_panel_multi_open),
+        );
+        // Keep appearance key for Tauri compatibility.
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "panel_multi_open"],
+            serde_json::Value::Bool(settings.ui_panel_multi_open),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "left_open_panels"],
+            string_vec_json_value(&settings.ui_left_open_panels, 32),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "right_open_panels"],
+            string_vec_json_value(&settings.ui_right_open_panels, 32),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "panel_stack_sizes"],
+            u32_map_json_value(&settings.ui_panel_stack_sizes),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["ui", "saved_connections_sort_mode"],
+            normalize_saved_connections_sort_mode(&settings.ui_saved_connections_sort_mode),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_appearance_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_string(&mut value, &["appearance", "theme"], settings.theme.clone());
+        match settings
+            .background_image_path
+            .as_deref()
+            .map(str::trim)
+            .filter(|s| !s.is_empty())
+        {
+            Some(path) => set_nested_json_string(
+                &mut value,
+                &["appearance", "background_image_path"],
+                path.to_string(),
+            ),
+            None => set_nested_json_value(
+                &mut value,
+                &["appearance", "background_image_path"],
+                serde_json::Value::Null,
+            ),
+        }
+        set_nested_json_string(
+            &mut value,
+            &["appearance", "background_image_fit"],
+            settings.background_image_fit.clone(),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "background_image_opacity"],
+            serde_json::Value::from(settings.background_image_opacity as f64 / 100.0),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "background_opacity"],
+            serde_json::Value::from(settings.background_content_opacity as f64 / 100.0),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["appearance", "font_family"],
+            settings.terminal_font_family.clone(),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "font_size"],
+            serde_json::Value::from(settings.terminal_font_size),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["appearance", "cursor_style"],
+            match settings.cursor_style.as_str() {
+                "underline" | "bar" => settings.cursor_style.clone(),
+                _ => "block".to_string(),
+            },
+        );
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "cursor_blink"],
+            serde_json::Value::from(settings.cursor_blink),
+        );
+        match settings
+            .terminal_theme
+            .as_deref()
+            .map(str::trim)
+            .filter(|s| !s.is_empty())
+        {
+            Some(theme) => set_nested_json_string(
+                &mut value,
+                &["appearance", "terminal_theme"],
+                theme.to_string(),
+            ),
+            None => set_nested_json_value(
+                &mut value,
+                &["appearance", "terminal_theme"],
+                serde_json::Value::Null,
+            ),
+        }
+        let contrast = match settings.minimum_contrast_ratio.as_str() {
+            "3" => 3.0,
+            "4.5" => 4.5,
+            "7" => 7.0,
+            "21" => 21.0,
+            _ => 1.0,
+        };
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "minimum_contrast_ratio"],
+            serde_json::Value::from(contrast),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["appearance", "ui_font_family"],
+            if settings.ui_font_family.trim().is_empty() {
+                "Inter".to_string()
+            } else {
+                settings.ui_font_family.clone()
+            },
+        );
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "ui_font_size"],
+            serde_json::Value::from(settings.ui_font_size.clamp(12, 24)),
+        );
+        let font_weight = match settings.terminal_font_weight {
+            300 | 400 | 500 | 600 | 700 | 800 => settings.terminal_font_weight,
+            _ => 400,
+        };
+        let font_weight_bold = match settings.terminal_font_weight_bold {
+            300 | 400 | 500 | 600 | 700 | 800 => settings.terminal_font_weight_bold,
+            _ => 700,
+        };
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "font_weight"],
+            serde_json::Value::from(font_weight),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["appearance", "font_weight_bold"],
+            serde_json::Value::from(font_weight_bold),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["terminal", "x11_display"],
+            settings.x11_display.clone(),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_terminal_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_string(
+            &mut value,
+            &["terminal", "x11_display"],
+            settings.x11_display.clone(),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "scrollback_lines"],
+            serde_json::Value::from(settings.terminal_scrollback_lines.clamp(100, 100_000)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "keep_alive_interval"],
+            serde_json::Value::from(settings.terminal_keep_alive_interval.min(600)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "hardware_acceleration"],
+            serde_json::Value::Bool(settings.terminal_hardware_acceleration),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "show_workspace_padding"],
+            serde_json::Value::Bool(settings.terminal_show_workspace_padding),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "show_line_numbers"],
+            serde_json::Value::Bool(settings.terminal_show_line_numbers),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "show_timestamps"],
+            serde_json::Value::Bool(settings.terminal_show_timestamps),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "show_timestamp_milliseconds"],
+            serde_json::Value::Bool(settings.terminal_show_timestamp_milliseconds),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "show_multi_line_paste_dialog"],
+            serde_json::Value::Bool(settings.terminal_show_multi_line_paste_dialog),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "paste_image_as_path"],
+            serde_json::Value::Bool(settings.terminal_paste_image_as_path),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "low_latency_mode"],
+            serde_json::Value::Bool(settings.terminal_low_latency_mode),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "action_links_enabled"],
+            serde_json::Value::Bool(settings.terminal_action_links_enabled),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["terminal", "action_links_matchers"],
+            serde_json::json!({
+                "ipv4": settings.terminal_action_links_matchers.ipv4,
+                "archive": settings.terminal_action_links_matchers.archive,
+                "host_port": settings.terminal_action_links_matchers.host_port,
+            }),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["search", "custom_engines"],
+            search_engines_to_json(&settings.search_custom_engines),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "show_remote_stats"],
+            serde_json::Value::Bool(settings.ui_show_remote_stats),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "remote_stats_interval"],
+            serde_json::Value::from(settings.ui_remote_stats_interval.clamp(1, 60)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "show_process_manager"],
+            serde_json::Value::Bool(settings.ui_show_process_manager),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "process_manager_interval"],
+            serde_json::Value::from(settings.ui_process_manager_interval.clamp(3, 120)),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "show_docker_manager"],
+            serde_json::Value::Bool(settings.ui_show_docker_manager),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["ui", "docker_manager_interval"],
+            serde_json::Value::from(settings.ui_docker_manager_interval.clamp(3, 120)),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_interaction_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        let min_chars = settings
+            .interaction_command_suggestion_min_chars
+            .clamp(1, 500);
+        let max_chars = settings
+            .interaction_command_suggestion_max_chars
+            .clamp(min_chars, 500);
+        set_nested_json_value(
+            &mut value,
+            &["interaction", "copy_on_select"],
+            serde_json::Value::Bool(settings.interaction_copy_on_select),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["interaction", "right_click_paste"],
+            serde_json::Value::Bool(settings.interaction_right_click_paste),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["interaction", "command_suggestions_enabled"],
+            serde_json::Value::Bool(settings.interaction_command_suggestions_enabled),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["interaction", "command_suggestion_min_chars"],
+            serde_json::Value::from(min_chars),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["interaction", "command_suggestion_max_chars"],
+            serde_json::Value::from(max_chars),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["interaction", "word_separators"],
+            settings.interaction_word_separators.clone(),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["interaction", "duplicate_session_command_delay_ms"],
+            serde_json::Value::from(
+                settings
+                    .interaction_duplicate_session_command_delay_ms
+                    .min(60_000),
+            ),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["interaction", "alt_as_meta"],
+            serde_json::Value::Bool(settings.interaction_alt_as_meta),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["interaction", "mac_ime_compatibility"],
+            serde_json::Value::Bool(settings.interaction_mac_ime_compatibility),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["interaction", "tab_double_click_action"],
+            normalize_tab_mouse_action(&settings.interaction_tab_double_click_action),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["interaction", "tab_middle_click_action"],
+            normalize_tab_mouse_action(&settings.interaction_tab_middle_click_action),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["interaction", "tab_right_click_action"],
+            normalize_tab_mouse_action(&settings.interaction_tab_right_click_action),
+        );
+        set_nested_json_string(
+            &mut value,
+            &["interaction", "default_encoding"],
+            normalize_interaction_encoding(&settings.interaction_default_encoding),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_general_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_value(
+            &mut value,
+            &["general", "startup_restore"],
+            serde_json::Value::Bool(settings.startup_restore),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["general", "startup_restore_window_layout"],
+            serde_json::Value::Bool(settings.startup_restore_window_layout),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["general", "minimize_to_tray"],
+            serde_json::Value::Bool(settings.minimize_to_tray),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["general", "confirm_on_close"],
+            serde_json::Value::Bool(settings.confirm_on_close),
+        );
+        // UI language lives under ui.language (Tauri UiConfig.language).
+        let language = match settings.language.as_str() {
+            "zh-CN" | "zh" => "zh-CN",
+            "zh-TW" => "zh-TW",
+            "ja" => "ja",
+            _ => "en",
+        };
+        set_nested_json_string(&mut value, &["ui", "language"], language.to_string());
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_diagnostics_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        let level = match settings.diagnostics_level.as_str() {
+            "warn" | "debug" => settings.diagnostics_level.as_str(),
+            _ => "info",
+        };
+        let retention = match settings.diagnostics_retention_days {
+            3 | 7 | 14 | 30 => settings.diagnostics_retention_days,
+            _ => 7,
+        };
+        set_nested_json_string(&mut value, &["diagnostics", "level"], level.to_string());
+        set_nested_json_value(
+            &mut value,
+            &["diagnostics", "retention_days"],
+            serde_json::Value::from(retention),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn load_open_tabs(&self) -> Result<Vec<crate::models::RestorableOpenTab>, StorageError> {
+        let value = self.load_settings_value()?;
+        let Some(raw) = json_path(&value, &["ui", "open_tabs"]) else {
+            return Ok(Vec::new());
+        };
+        if raw.is_null() {
+            return Ok(Vec::new());
+        }
+        match serde_json::from_value::<Vec<crate::models::RestorableOpenTab>>(raw.clone()) {
+            Ok(tabs) => Ok(tabs),
+            Err(_) => Ok(Vec::new()),
+        }
+    }
+
+    pub fn save_open_tabs(
+        &self,
+        tabs: &[crate::models::RestorableOpenTab],
+    ) -> Result<(), StorageError> {
+        let mut value = self.load_settings_value()?;
+        let encoded = serde_json::to_value(tabs)?;
+        set_nested_json_value(&mut value, &["ui", "open_tabs"], encoded);
+        self.save_settings_value(&value)?;
+        Ok(())
+    }
+
+    pub fn load_terminal_window_layout(
+        &self,
+    ) -> Result<Option<crate::models::RestorableTerminalWindowNode>, StorageError> {
+        let value = self.load_settings_value()?;
+        let Some(raw) = json_path(&value, &["ui", "terminal_window_layout"]) else {
+            return Ok(None);
+        };
+        if raw.is_null() {
+            return Ok(None);
+        }
+        match serde_json::from_value(raw.clone()) {
+            Ok(node) => Ok(Some(node)),
+            Err(_) => Ok(None),
+        }
+    }
+
+    pub fn save_terminal_window_layout(
+        &self,
+        layout: Option<&crate::models::RestorableTerminalWindowNode>,
+    ) -> Result<(), StorageError> {
+        let mut value = self.load_settings_value()?;
+        let encoded = match layout {
+            Some(node) => serde_json::to_value(node)?,
+            None => serde_json::Value::Null,
+        };
+        set_nested_json_value(&mut value, &["ui", "terminal_window_layout"], encoded);
+        self.save_settings_value(&value)?;
+        Ok(())
+    }
+
+    pub fn load_workspace_pane_layout(
+        &self,
+    ) -> Result<Option<crate::models::RestorableWorkspacePaneNode>, StorageError> {
+        let value = self.load_settings_value()?;
+        let Some(raw) = json_path(&value, &["ui", "workspace_pane_layout"]) else {
+            return Ok(None);
+        };
+        if raw.is_null() {
+            return Ok(None);
+        }
+        match serde_json::from_value(raw.clone()) {
+            Ok(node) => Ok(Some(node)),
+            Err(_) => Ok(None),
+        }
+    }
+
+    pub fn save_workspace_pane_layout(
+        &self,
+        layout: Option<&crate::models::RestorableWorkspacePaneNode>,
+    ) -> Result<(), StorageError> {
+        let mut value = self.load_settings_value()?;
+        let encoded = match layout {
+            Some(node) => serde_json::to_value(node)?,
+            None => serde_json::Value::Null,
+        };
+        set_nested_json_value(&mut value, &["ui", "workspace_pane_layout"], encoded);
+        self.save_settings_value(&value)?;
+        Ok(())
+    }
+
+    pub fn save_screen_lock_settings(
+        &self,
+        settings: &AppSettingsSummary,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        set_nested_json_value(
+            &mut value,
+            &["security", "enable_screen_lock"],
+            serde_json::Value::Bool(settings.enable_screen_lock),
+        );
+        set_nested_json_value(
+            &mut value,
+            &["security", "idle_lock_minutes"],
+            serde_json::Value::from(settings.idle_lock_minutes),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+
+    pub fn save_keybindings(
+        &self,
+        keybindings: &HashMap<String, String>,
+    ) -> Result<AppSettingsSummary, StorageError> {
+        let mut value = self.load_settings_value()?;
+        let mut object = serde_json::Map::new();
+        for (id, keys) in keybindings {
+            let id = id.trim();
+            let keys = keys.trim();
+            if !id.is_empty() && !keys.is_empty() {
+                object.insert(id.to_string(), serde_json::Value::String(keys.to_string()));
+            }
+        }
+        set_nested_json_value(
+            &mut value,
+            &["keybindings"],
+            serde_json::Value::Object(object),
+        );
+        self.save_settings_value(&value)?;
+        self.load_app_settings_summary()
+    }
+}
+
+fn default_activity_left_bottom() -> Vec<String> {
+    vec!["syncBackupHistory".to_string(), "settings".to_string()]
+}
+
+fn default_activity_left_top() -> Vec<String> {
+    vec![
+        "fileExplorer".to_string(),
+        "network".to_string(),
+        "securityAuth".to_string(),
+    ]
+}
+
+fn default_activity_right_bottom() -> Vec<String> {
+    vec![
+        "quickCmdBar".to_string(),
+        "serialSend".to_string(),
+        "recording".to_string(),
+        "lock".to_string(),
+    ]
+}
+
+fn default_activity_right_top() -> Vec<String> {
+    vec![
+        "savedConnections".to_string(),
+        "aiAssistant".to_string(),
+        "activeSessions".to_string(),
+        "commandHistory".to_string(),
+        "resourceMonitor".to_string(),
+        "processManager".to_string(),
+        "dockerManager".to_string(),
+    ]
+}
+
+fn json_optional_string(value: &serde_json::Value, path: &[&str]) -> Option<String> {
+    json_path(value, path)
+        .and_then(|value| value.as_str())
+        .map(str::trim)
+        .filter(|value| !value.is_empty())
+        .map(ToOwned::to_owned)
+}
+
+fn json_string(value: &serde_json::Value, path: &[&str], fallback: &str) -> String {
+    json_path(value, path)
+        .and_then(serde_json::Value::as_str)
+        .filter(|value| !value.is_empty())
+        .unwrap_or(fallback)
+        .to_string()
+}
+
+fn json_string_map(value: &serde_json::Value, path: &[&str]) -> HashMap<String, String> {
+    json_path(value, path)
+        .and_then(serde_json::Value::as_object)
+        .map(|object| {
+            object
+                .iter()
+                .filter_map(|(key, value)| {
+                    value
+                        .as_str()
+                        .filter(|value| !value.trim().is_empty())
+                        .map(|value| (key.clone(), value.to_string()))
+                })
+                .collect()
+        })
+        .unwrap_or_default()
+}
+
+fn json_string_vec_map(
+    value: &serde_json::Value,
+    path: &[&str],
+    limit_per_key: usize,
+) -> HashMap<String, Vec<String>> {
+    json_path(value, path)
+        .and_then(serde_json::Value::as_object)
+        .map(|object| {
+            object
+                .iter()
+                .filter_map(|(key, value)| {
+                    let values = value
+                        .as_array()?
+                        .iter()
+                        .filter_map(|entry| {
+                            entry
+                                .as_str()
+                                .map(str::trim)
+                                .filter(|entry| !entry.is_empty())
+                                .map(ToOwned::to_owned)
+                        })
+                        .fold(Vec::<String>::new(), |mut values, entry| {
+                            if !values.iter().any(|existing| existing == &entry) {
+                                values.push(entry);
+                            }
+                            values
+                        })
+                        .into_iter()
+                        .take(limit_per_key)
+                        .collect::<Vec<_>>();
+                    (!values.is_empty()).then(|| (key.clone(), values))
+                })
+                .collect()
+        })
+        .unwrap_or_default()
+}
+
+fn json_string_vec_with_default(
+    value: &serde_json::Value,
+    path: &[&str],
+    limit: usize,
+    default: fn() -> Vec<String>,
+) -> Vec<String> {
+    if json_path(value, path).is_some() {
+        json_string_vec(value, path, limit)
+    } else {
+        default()
+    }
+}
+
+fn json_u16(value: &serde_json::Value, path: &[&str], fallback: u16) -> u16 {
+    let Some(value) = json_path(value, path) else {
+        return fallback;
+    };
+    if let Some(number) = value.as_u64() {
+        return number.try_into().unwrap_or(fallback);
+    }
+    if let Some(number) = value.as_f64() {
+        if number.is_finite() && number >= 0.0 && number <= f64::from(u16::MAX) {
+            return number.round() as u16;
+        }
+    }
+    fallback
+}
+
+fn json_u32(value: &serde_json::Value, path: &[&str], fallback: u32) -> u32 {
+    let Some(value) = json_path(value, path) else {
+        return fallback;
+    };
+    if let Some(number) = value.as_u64() {
+        return number.try_into().unwrap_or(fallback);
+    }
+    if let Some(number) = value.as_f64() {
+        if number.is_finite() && number >= 0.0 && number <= f64::from(u32::MAX) {
+            return number.round() as u32;
+        }
+    }
+    fallback
+}
+
+fn json_u32_map(value: &serde_json::Value, path: &[&str]) -> HashMap<String, u32> {
+    let mut map = HashMap::new();
+    let Some(object) = json_path(value, path).and_then(|value| value.as_object()) else {
+        return map;
+    };
+    for (key, raw) in object {
+        let number = raw
+            .as_u64()
+            .or_else(|| raw.as_f64().map(|value| value.round() as u64));
+        if let Some(number) = number {
+            if number > 0 {
+                map.insert(key.clone(), number.min(u32::MAX as u64) as u32);
+            }
+        }
+    }
+    map
+}
+
+fn json_u64(value: &serde_json::Value, path: &[&str], fallback: u64) -> u64 {
+    let Some(value) = json_path(value, path) else {
+        return fallback;
+    };
+    if let Some(number) = value.as_u64() {
+        return number;
+    }
+    if let Some(number) = value.as_f64() {
+        if number.is_finite() && number >= 0.0 && number <= u64::MAX as f64 {
+            return number.round() as u64;
+        }
+    }
+    fallback
+}
+
+fn load_action_links_matchers(value: &serde_json::Value) -> crate::ActionLinksMatcherSettings {
+    let defaults = crate::ActionLinksMatcherSettings::default();
+    let Some(obj) = json_path(value, &["terminal", "action_links_matchers"]) else {
+        return defaults;
+    };
+    crate::ActionLinksMatcherSettings {
+        ipv4: obj
+            .get("ipv4")
+            .and_then(|v| v.as_bool())
+            .unwrap_or(defaults.ipv4),
+        archive: obj
+            .get("archive")
+            .and_then(|v| v.as_bool())
+            .unwrap_or(defaults.archive),
+        host_port: obj
+            .get("host_port")
+            .and_then(|v| v.as_bool())
+            .unwrap_or(defaults.host_port),
+    }
+}
+
+fn load_search_engines(value: &serde_json::Value) -> Vec<SearchEngineConfig> {
+    let Some(arr) = json_path(value, &["search", "custom_engines"]).and_then(|v| v.as_array())
+    else {
+        return default_search_engines();
+    };
+    let mut engines = Vec::new();
+    for item in arr {
+        if !item.is_object() {
+            continue;
+        }
+        let name = item
+            .get("name")
+            .and_then(|v| v.as_str())
+            .unwrap_or("")
+            .trim()
+            .to_string();
+        let url_template = item
+            .get("url_template")
+            .and_then(|v| v.as_str())
+            .unwrap_or("")
+            .trim()
+            .to_string();
+        let show_in_menu = item
+            .get("show_in_menu")
+            .and_then(|v| v.as_bool())
+            .unwrap_or(true);
+        let icon = item
+            .get("icon")
+            .and_then(|v| v.as_str())
+            .map(str::trim)
+            .filter(|s| !s.is_empty())
+            .map(ToString::to_string);
+        engines.push(SearchEngineConfig {
+            name,
+            url_template,
+            icon,
+            show_in_menu,
+        });
+    }
+    engines
+}
+
+fn normalize_host_key_policy(policy: &str) -> String {
+    match policy {
+        "strict" | "accept" | "prompt" => policy.to_string(),
+        _ => "prompt".to_string(),
+    }
+}
+
+fn normalize_interaction_encoding(encoding: &str) -> String {
+    if encoding.eq_ignore_ascii_case("gbk") {
+        "GBK".to_string()
+    } else {
+        "UTF-8".to_string()
+    }
+}
+
+fn normalize_quick_cmd_sort_mode(value: &str) -> String {
+    match value.trim() {
+        "created" | "name" | "useCount" => value.trim().to_string(),
+        _ => "created".to_string(),
+    }
+}
+
+fn normalize_quick_cmd_view_mode(value: &str) -> String {
+    match value.trim() {
+        "list" | "compact" | "tile" => value.trim().to_string(),
+        _ => "tile".to_string(),
+    }
+}
+
+fn normalize_saved_connections_sort_mode(value: &str) -> String {
+    match value.trim() {
+        "name-asc" | "name-desc" => value.trim().to_string(),
+        _ => "default".to_string(),
+    }
+}
+
+fn normalize_tab_mouse_action(action: &str) -> String {
+    match action {
+        "none" | "rename_tab" | "copy_tab_name" | "copy_server_ip" | "duplicate_session"
+        | "multiplex_ssh" | "reconnect_session" | "disconnect_session" | "close_tab" => {
+            action.to_string()
+        }
+        _ => "none".to_string(),
+    }
+}
+
+fn normalize_transfer_duplicate_strategy(strategy: &str) -> String {
+    match strategy {
+        "ask" | "overwrite" | "skip" | "rename" => strategy.to_string(),
+        _ => "ask".to_string(),
+    }
+}
+
+fn normalize_transfer_editor_type(editor_type: &str) -> String {
+    match editor_type {
+        "external" | "internal" => editor_type.to_string(),
+        _ => "external".to_string(),
+    }
+}
+
+fn normalize_transfer_file_permissions(value: &str) -> String {
+    let trimmed = value
+        .trim()
+        .trim_start_matches("0o")
+        .trim_start_matches('0');
+    let normalized = if trimmed.is_empty() { "0" } else { trimmed };
+    if (3..=4).contains(&normalized.len()) && normalized.chars().all(|ch| matches!(ch, '0'..='7')) {
+        normalized.to_string()
+    } else {
+        "644".to_string()
+    }
+}
+
+fn search_engines_to_json(engines: &[SearchEngineConfig]) -> serde_json::Value {
+    serde_json::Value::Array(
+        engines
+            .iter()
+            .map(|engine| {
+                serde_json::json!({
+                    "name": engine.name,
+                    "url_template": engine.url_template,
+                    "icon": engine.icon,
+                    "show_in_menu": engine.show_in_menu,
+                })
+            })
+            .collect(),
+    )
+}
+
+fn set_nested_json_string(value: &mut serde_json::Value, path: &[&str], new_value: String) {
+    set_nested_json_value(value, path, serde_json::Value::String(new_value));
+}
+
+fn string_vec_json_value(values: &[String], limit: usize) -> serde_json::Value {
+    serde_json::Value::Array(
+        values
+            .iter()
+            .map(|value| value.trim())
+            .filter(|value| !value.is_empty())
+            .fold(Vec::<String>::new(), |mut values, value| {
+                if !values.iter().any(|existing| existing == value) {
+                    values.push(value.to_string());
+                }
+                values
+            })
+            .into_iter()
+            .take(limit)
+            .map(serde_json::Value::String)
+            .collect(),
+    )
+}
+
+fn string_vec_map_json_value(
+    map: &HashMap<String, Vec<String>>,
+    limit_per_key: usize,
+) -> serde_json::Value {
+    let object = map
+        .iter()
+        .filter_map(|(key, values)| {
+            let key = key.trim();
+            if key.is_empty() {
+                return None;
+            }
+            let values = values
+                .iter()
+                .map(|value| value.trim())
+                .filter(|value| !value.is_empty())
+                .fold(Vec::<String>::new(), |mut values, value| {
+                    if !values.iter().any(|existing| existing == value) {
+                        values.push(value.to_string());
+                    }
+                    values
+                })
+                .into_iter()
+                .take(limit_per_key)
+                .map(serde_json::Value::String)
+                .collect::<Vec<_>>();
+            (!values.is_empty()).then(|| (key.to_string(), serde_json::Value::Array(values)))
+        })
+        .collect();
+    serde_json::Value::Object(object)
+}
+
+fn u32_map_json_value(map: &HashMap<String, u32>) -> serde_json::Value {
+    let mut object = serde_json::Map::new();
+    for (key, value) in map {
+        if *value > 0 {
+            object.insert(key.clone(), serde_json::json!(*value));
+        }
+    }
+    serde_json::Value::Object(object)
+}