refactor(workspace): migrate from per-folder windows to single-window workspace

Replace the legacy folder + welcome routes with a unified /workspace route
that hosts all folders, conversations, tabs, and terminals in one window.

- Persist opened tabs to the database (opened_tabs entity + migration)
  so tab layout survives restarts and deep-link bootstrap restores state
- Replace FolderContext shim with AppWorkspaceProvider, ActiveFolderProvider,
  and TabProvider; expose both opened (folders) and full DB (allFolders)
  listings via list_all_folder_details
- Return conversations across all non-deleted folders from list_all when
  no folder filter is given, so the sidebar can show every folder's history
- Add ConversationContextBar above the chat input with folder picker
  (auto-opens unopened folders on select), branch picker, and commit /
  push / merge / stash entries to restore BranchDropdown functionality
- Rework sidebar with stats header, search, flat / folder-grouped view
  modes (localStorage-persisted), reveal-in-sidebar event subscriber,
  and per-folder context menu (focus, close tabs, remove from workspace);
  indent conversations under folder headers in grouped mode
- Gate terminal creation on active folder and show folder context
- Remove deprecated BranchDropdown, FolderNameDropdown, welcome route,
  and per-folder window commands
- Localize all new strings across 10 locales

src-tauri/src/web/handlers/conversations.rs

@@ -9,24 +9,24 @@ use crate::commands::conversations as conv_commands;
 use crate::db::service::{conversation_service, folder_service, import_service};
 use crate::models::*;
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Default)]
 #[serde(rename_all = "camelCase")]
-pub struct ListFolderConversationsParams {
-    pub folder_id: i32,
+pub struct ListAllConversationsParams {
+    pub folder_ids: Option<Vec<i32>>,
     pub agent_type: Option<AgentType>,
     pub search: Option<String>,
     pub sort_by: Option<String>,
     pub status: Option<String>,
 }
 
-pub async fn list_folder_conversations(
+pub async fn list_all_conversations(
     Extension(state): Extension<Arc<AppState>>,
-    Json(params): Json<ListFolderConversationsParams>,
+    Json(params): Json<ListAllConversationsParams>,
 ) -> Result<Json<Vec<DbConversationSummary>>, AppCommandError> {
     let db = &state.db;
-    let result = conversation_service::list_by_folder(
+    let result = conversation_service::list_all(
         &db.conn,
-        params.folder_id,
+        params.folder_ids,
         params.agent_type,
         params.search,
         params.sort_by,
@@ -37,6 +37,35 @@ pub async fn list_folder_conversations(
     Ok(Json(result))
 }
 
+pub async fn list_opened_tabs(
+    Extension(state): Extension<Arc<AppState>>,
+) -> Result<Json<Vec<OpenedTab>>, AppCommandError> {
+    use crate::db::service::tab_service;
+    let db = &state.db;
+    let result = tab_service::list_all_tabs(&db.conn)
+        .await
+        .map_err(AppCommandError::from)?;
+    Ok(Json(result))
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct SaveOpenedTabsParams {
+    pub items: Vec<OpenedTab>,
+}
+
+pub async fn save_opened_tabs(
+    Extension(state): Extension<Arc<AppState>>,
+    Json(params): Json<SaveOpenedTabsParams>,
+) -> Result<Json<()>, AppCommandError> {
+    use crate::db::service::tab_service;
+    let db = &state.db;
+    tab_service::save_all_tabs(&db.conn, params.items)
+        .await
+        .map_err(AppCommandError::from)?;
+    Ok(Json(()))
+}
+
 #[derive(Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct ListConversationsParams {

src-tauri/src/web/handlers/folders.rs

@@ -53,45 +53,71 @@ pub struct AddFolderParams {
     pub path: String,
 }
 
-/// Web equivalent of `open_folder_window`: adds the folder to DB and returns its ID.
-/// The web client then navigates to `/folder?id=N` itself.
-pub async fn open_folder_window(
+/// Add the folder to the workspace (upsert + set is_open=true) and return its full detail.
+/// Previously this spawned a new window; the new single-window workspace model
+/// simply returns the folder info so the client can update its local state.
+pub async fn open_folder(
     Extension(state): Extension<Arc<AppState>>,
     Json(params): Json<AddFolderParams>,
-) -> Result<Json<FolderHistoryEntry>, AppCommandError> {
+) -> Result<Json<FolderDetail>, AppCommandError> {
     let db = &state.db;
     let entry = folder_service::add_folder(&db.conn, &params.path)
         .await
         .map_err(AppCommandError::from)?;
-    Ok(Json(entry))
+    let folder = folder_service::get_folder_by_id(&db.conn, entry.id)
+        .await
+        .map_err(AppCommandError::from)?
+        .ok_or_else(|| AppCommandError::not_found("Folder not found after add"))?;
+    Ok(Json(folder))
 }
 
-pub async fn close_folder_window(
+// --- New workspace handlers ---
+
+pub async fn list_open_folder_details(
+    Extension(state): Extension<Arc<AppState>>,
+) -> Result<Json<Vec<FolderDetail>>, AppCommandError> {
+    let db = &state.db;
+    let result = folder_service::list_open_folder_details(&db.conn)
+        .await
+        .map_err(AppCommandError::from)?;
+    Ok(Json(result))
+}
+
+pub async fn list_all_folder_details(
+    Extension(state): Extension<Arc<AppState>>,
+) -> Result<Json<Vec<FolderDetail>>, AppCommandError> {
+    let db = &state.db;
+    let result = folder_service::list_all_folder_details(&db.conn)
+        .await
+        .map_err(AppCommandError::from)?;
+    Ok(Json(result))
+}
+
+pub async fn open_folder_by_id(
+    Extension(state): Extension<Arc<AppState>>,
+    Json(params): Json<FolderIdParams>,
+) -> Result<Json<FolderDetail>, AppCommandError> {
+    let db = &state.db;
+    folder_service::set_folder_open(&db.conn, params.folder_id, true)
+        .await
+        .map_err(AppCommandError::from)?;
+    let folder = folder_service::get_folder_by_id(&db.conn, params.folder_id)
+        .await
+        .map_err(AppCommandError::from)?
+        .ok_or_else(|| AppCommandError::not_found("Folder not found"))?;
+    Ok(Json(folder))
+}
+
+pub async fn remove_folder_from_workspace(
     Extension(state): Extension<Arc<AppState>>,
     Json(params): Json<FolderIdParams>,
 ) -> Result<Json<()>, AppCommandError> {
+    use crate::db::service::tab_service;
     let db = &state.db;
-    folder_service::set_folder_open(&db.conn, params.folder_id, false)
+    tab_service::delete_tabs_for_folder(&db.conn, params.folder_id)
         .await
         .map_err(AppCommandError::from)?;
-    Ok(Json(()))
-}
-
-// --- New handlers below ---
-
-#[derive(Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub struct SaveFolderOpenedConversationsParams {
-    pub folder_id: i32,
-    pub items: Vec<OpenedConversation>,
-}
-
-pub async fn save_folder_opened_conversations(
-    Extension(state): Extension<Arc<AppState>>,
-    Json(params): Json<SaveFolderOpenedConversationsParams>,
-) -> Result<Json<()>, AppCommandError> {
-    let db = &state.db;
-    folder_service::save_opened_conversations(&db.conn, params.folder_id, params.items)
+    folder_service::set_folder_open(&db.conn, params.folder_id, false)
         .await
         .map_err(AppCommandError::from)?;
     Ok(Json(()))

src-tauri/src/web/router.rs

@@ -34,13 +34,21 @@ pub fn build_router(state: Arc<AppState>, token: String, static_dir: std::path::
             post(handlers::conversations::get_conversation),
         )
         .route(
-            "/list_folder_conversations",
-            post(handlers::conversations::list_folder_conversations),
+            "/list_all_conversations",
+            post(handlers::conversations::list_all_conversations),
         )
         .route(
             "/get_folder_conversation",
             post(handlers::conversations::get_folder_conversation),
         )
+        .route(
+            "/list_opened_tabs",
+            post(handlers::conversations::list_opened_tabs),
+        )
+        .route(
+            "/save_opened_tabs",
+            post(handlers::conversations::save_opened_tabs),
+        )
         .route(
             "/import_local_conversations",
             post(handlers::conversations::import_local_conversations),
@@ -81,13 +89,22 @@ pub fn build_router(state: Arc<AppState>, token: String, static_dir: std::path::
             post(handlers::folders::list_open_folders),
         )
         .route(
-            "/close_folder_window",
-            post(handlers::folders::close_folder_window),
+            "/list_open_folder_details",
+            post(handlers::folders::list_open_folder_details),
+        )
+        .route(
+            "/list_all_folder_details",
+            post(handlers::folders::list_all_folder_details),
         )
         .route("/get_folder", post(handlers::folders::get_folder))
+        .route("/open_folder", post(handlers::folders::open_folder))
         .route(
-            "/open_folder_window",
-            post(handlers::folders::open_folder_window),
+            "/open_folder_by_id",
+            post(handlers::folders::open_folder_by_id),
+        )
+        .route(
+            "/remove_folder_from_workspace",
+            post(handlers::folders::remove_folder_from_workspace),
         )
         .route(
             "/add_folder_to_history",
@@ -105,10 +122,6 @@ pub fn build_router(state: Arc<AppState>, token: String, static_dir: std::path::
             "/create_folder_directory",
             post(handlers::folders::create_folder_directory),
         )
-        .route(
-            "/save_folder_opened_conversations",
-            post(handlers::folders::save_folder_opened_conversations),
-        )
         .route("/get_git_branch", post(handlers::folders::get_git_branch))
         .route(
             "/get_home_directory",