chore(commands): delete legacy commands module and inline helpers

src-tauri/src/commands/user_session.rs hosted three unregistered
#[tauri::command] entries (activate_user_session, deactivate_user_session,
get_last_user_id) plus two non-command helpers (init_type_alias_state,
teardown_type_alias_state) consumed only by session_lifecycle.rs.

- Move init_type_alias_state and teardown_type_alias_state into
  session_lifecycle.rs (their only caller) as plain pub helpers.
- Delete src-tauri/src/commands/user_session.rs and
  src-tauri/src/commands/mod.rs.
- Remove pub mod commands; from lib.rs — the legacy commands
  namespace is now empty.
- Refresh the activate_session doc comment to match the new layout.

cc

src-tauri/src/commands/mod.rs

@@ -1,9 +0,0 @@
-//! Legacy commands module.
-//!
-//! NOTE:
-//! The active frontend/runtime contract is V2 (`runtime_*` + `v2_*`) only.
-//! This module keeps only the minimal internal legacy pieces still referenced
-//! by non-frontend subsystems while hard-delete migration is in progress.
-
-pub mod user_session;
-pub use user_session::*;

src-tauri/src/commands/user_session.rs

@@ -1,64 +0,0 @@
-//! Per-user session activation and teardown
-//!
-//! After login, the frontend calls `activate_user_session` with the Qobuz user_id.
-//! This initializes all per-user database stores at the user-scoped directory.
-//! On logout, `deactivate_user_session` tears everything down.
-//!
-//! These legacy commands now delegate to session_lifecycle module.
-
-use std::path::Path;
-use std::sync::{Arc, Mutex};
-
-use crate::user_data::UserDataPaths;
-
-/// Helper to init a type-alias state (Arc<Mutex<Option<Store>>>) at a path
-pub fn init_type_alias_state<S, F>(
-    state: &Arc<Mutex<Option<S>>>,
-    base_dir: &Path,
-    constructor: F,
-) -> Result<(), String>
-where
-    F: FnOnce(&Path) -> Result<S, String>,
-{
-    let store = constructor(base_dir)?;
-    let mut guard = state.lock().map_err(|e| format!("Lock error: {}", e))?;
-    *guard = Some(store);
-    Ok(())
-}
-
-/// Helper to teardown a type-alias state
-pub fn teardown_type_alias_state<S>(state: &Arc<Mutex<Option<S>>>) {
-    if let Ok(mut guard) = state.lock() {
-        *guard = None;
-    }
-}
-
-/// Get the last active user_id for session restore on startup.
-/// Returns None if no previous session or after explicit logout.
-#[tauri::command]
-pub fn get_last_user_id() -> Option<u64> {
-    UserDataPaths::load_last_user_id()
-}
-
-/// Activate the per-user session after login.
-///
-/// This runs the one-time migration (if needed) and initializes all
-/// per-user database stores at `~/.local/share/qbz/users/{user_id}/`
-/// and cache stores at `~/.cache/qbz/users/{user_id}/`.
-///
-/// This is a legacy command - now delegates to session_lifecycle::activate_session().
-#[tauri::command]
-pub async fn activate_user_session(app: tauri::AppHandle, user_id: u64) -> Result<(), String> {
-    log::info!("[Legacy] activate_user_session called - delegating to session_lifecycle");
-    crate::session_lifecycle::activate_session(&app, user_id).await
-}
-
-/// Deactivate the per-user session on logout.
-///
-/// Tears down all per-user stores, closing database connections.
-/// This is a legacy command - now delegates to session_lifecycle::deactivate_session().
-#[tauri::command]
-pub async fn deactivate_user_session(app: tauri::AppHandle) -> Result<(), String> {
-    log::info!("[Legacy] deactivate_user_session called - delegating to session_lifecycle");
-    crate::session_lifecycle::deactivate_session(&app).await
-}

src-tauri/src/lib.rs

@@ -35,7 +35,6 @@ pub mod audio;
 pub mod audio_device_watch;
 pub mod cache;
 pub mod cast;
-pub mod commands;
 pub mod config;
 pub mod credentials;
 pub mod discogs;

src-tauri/src/session_lifecycle.rs

@@ -7,11 +7,36 @@
 //! from multiple places (runtime_bootstrap, commands, etc.) without
 //! duplicating the complex state initialization logic.
 
+use std::path::Path;
+use std::sync::{Arc, Mutex};
+
 use tauri::{Emitter, Manager};
 
 use crate::runtime::{RuntimeEvent, RuntimeManagerState};
 use crate::user_data::UserDataPaths;
 
+/// Helper to init a type-alias state (Arc<Mutex<Option<Store>>>) at a path.
+pub fn init_type_alias_state<S, F>(
+    state: &Arc<Mutex<Option<S>>>,
+    base_dir: &Path,
+    constructor: F,
+) -> Result<(), String>
+where
+    F: FnOnce(&Path) -> Result<S, String>,
+{
+    let store = constructor(base_dir)?;
+    let mut guard = state.lock().map_err(|e| format!("Lock error: {}", e))?;
+    *guard = Some(store);
+    Ok(())
+}
+
+/// Helper to teardown a type-alias state.
+pub fn teardown_type_alias_state<S>(state: &Arc<Mutex<Option<S>>>) {
+    if let Ok(mut guard) = state.lock() {
+        *guard = None;
+    }
+}
+
 /// Activate a user session from anywhere given an AppHandle.
 ///
 /// This performs the full session activation:
@@ -21,8 +46,8 @@ use crate::user_data::UserDataPaths;
 /// 4. Updates runtime state
 /// 5. Emits UserSessionActivated event
 ///
-/// Note: This is the core logic extracted from `activate_user_session` command.
-/// It can be called from runtime_bootstrap, v2_login, or the command itself.
+/// Note: This is the core logic invoked from runtime_bootstrap and v2_login
+/// after the legacy `activate_user_session` Tauri command was retired.
 pub async fn activate_session(app: &tauri::AppHandle, user_id: u64) -> Result<(), String> {
     log::info!("[SessionLifecycle] Activating session");
 
@@ -171,12 +196,12 @@ pub async fn activate_session(app: &tauri::AppHandle, user_id: u64) -> Result<()
     use crate::config::{
         download_settings::DownloadSettingsStore, subscription_state::SubscriptionStateStore,
     };
-    crate::commands::user_session::init_type_alias_state(
+    init_type_alias_state(
         &*subscription_state,
         &data_dir,
         SubscriptionStateStore::new_at,
     )?;
-    crate::commands::user_session::init_type_alias_state(
+    init_type_alias_state(
         &*download_settings,
         &data_dir,
         DownloadSettingsStore::new_at,
@@ -327,8 +352,8 @@ pub async fn deactivate_session(app: &tauri::AppHandle) -> Result<(), String> {
 
     // Type-alias states (per-user settings)
     // NOTE: LegalSettingsState is GLOBAL (not per-user) - NOT torn down here
-    crate::commands::user_session::teardown_type_alias_state(&*subscription_state);
-    crate::commands::user_session::teardown_type_alias_state(&*download_settings);
+    teardown_type_alias_state(&*subscription_state);
+    teardown_type_alias_state(&*download_settings);
 
     // Clear the active user but KEEP last_user_id on disk.
     // Offline mode needs it to load the user's library and settings
@@ -420,7 +445,7 @@ pub async fn activate_offline_session(app: &tauri::AppHandle) -> Result<(), Stri
     // Download settings — needed for "Show in Local Library" toggle
     {
         use crate::config::download_settings::DownloadSettingsStore;
-        crate::commands::user_session::init_type_alias_state(
+        init_type_alias_state(
             &*download_settings,
             &data_dir,
             DownloadSettingsStore::new_at,