fix(tui): apply username folders everywhere and resume in place

Move the sanitizer next to the directory helpers so the CLI download
command and the daemon honour use_username_dirs too, not only the TUI.
Resumed downloads keep the folder they were saved with instead of
nesting the username a second time, and toggling the setting applies
to the next download without a restart. Document the config key.

soulseek-rs/src/ui/main_tui/downloads.rs

@@ -1,10 +1,9 @@
 use super::MainTui;
+use crate::directories::download_dir_for;
 use crate::models::{DownloadEntry, FileDisplayData};
 use crate::ui::panes::{InfoSubject, selected_transfer};
-use crate::ui::sanitize_path_component;
 use soulseek_rs::types::UploadStatus;
 use soulseek_rs::{DownloadStatus, types::Download};
-use std::path::Path;
 use std::{sync::mpsc, thread};
 
 impl MainTui {
@@ -209,21 +208,15 @@ impl MainTui {
                     peer_upload_speed: Some(file.speed),
                     peer_free_slots: Some(file.slots),
                 };
-                let download_dir = if use_username_dirs {
-                    let sanitized_username =
-                        sanitize_path_component(file.username.as_str());
-                    Path::new(download_dir.as_str())
-                        .join(sanitized_username.as_str())
-                        .display()
-                        .to_string()
-                } else {
-                    download_dir.clone()
-                };
                 match client.download_with_metadata(
                     file.filename.clone(),
                     file.username.clone(),
                     file.size,
-                    download_dir,
+                    download_dir_for(
+                        &download_dir,
+                        &file.username,
+                        use_username_dirs,
+                    ),
                     metadata,
                 ) {
                     Ok((download, rx)) => {

soulseek-rs/src/ui/main_tui/mod.rs

@@ -12,13 +12,11 @@ use crate::persist::{
     snapshot::{Snapshot, restore_messages, restore_searches},
     state::{PersistedMessage, StateStore},
 };
-use crate::ui::sanitize_path_component;
 use color_eyre::Result;
 use ratatui::{
     DefaultTerminal,
     crossterm::event::{self, Event, KeyEventKind, poll},
 };
-use std::path::Path;
 use std::{sync::Arc, time::Duration};
 
 pub struct MainTui {
@@ -134,23 +132,12 @@ impl MainTui {
             } else {
                 let client = self.client.clone();
                 let sender = sender.clone();
-                let use_username_dirs = self.use_username_dirs;
                 std::thread::spawn(move || {
-                    let sanitized_username =
-                        sanitize_path_component(entry.username.as_str());
-                    let download_dir = if use_username_dirs {
-                        Path::new(entry.download_directory.as_str())
-                            .join(sanitized_username.as_str())
-                            .display()
-                            .to_string()
-                    } else {
-                        entry.download_directory
-                    };
                     match client.download(
                         entry.filename.clone(),
                         entry.username,
                         entry.size,
-                        download_dir,
+                        entry.download_directory,
                     ) {
                         Ok((download, rx)) => {
                             let _ = sender.send((download, rx));
@@ -268,6 +255,7 @@ impl MainTui {
     }
 }
 
+#[expect(clippy::too_many_arguments, reason = "one call site per mode")]
 pub fn launch_main_tui(
     terminal: DefaultTerminal,
     client: Arc<dyn SessionApi>,

soulseek-rs/src/ui/main_tui/settings.rs

@@ -109,6 +109,7 @@ impl MainTui {
         if dir_applied {
             self.download_dir.clone_from(&download_dir);
         }
+        self.use_username_dirs = use_username_dirs;
 
         // Persist to config.toml so the change survives a restart. What was
         // refused live is not written either: the file must not promise a

soulseek-rs/src/ui/main_tui/tests/settings.rs

@@ -108,6 +108,30 @@ fn applying_settings_locally_stays_on_this_machine() {
     assert_eq!(tui.download_dir, downloads_dir);
 }
 
+#[test]
+fn toggling_username_folders_applies_live_and_persists() {
+    let session = Arc::new(TalkativeSession::default());
+    let scratch = tempfile::tempdir().expect("a temp dir");
+    let config_path = scratch.path().join("config.toml");
+    let mut tui = MainTui::new(
+        session,
+        scratch.path().to_str().expect("utf-8").to_string(),
+        false,
+        Duration::from_secs(1),
+        None,
+        Some(config_path.clone()),
+    );
+
+    tui.open_settings();
+    tui.state.settings.as_mut().expect("open").use_username_dirs = true;
+    tui.apply_settings();
+
+    assert!(tui.use_username_dirs, "the next download uses it");
+    let saved = crate::persist::config::FileConfig::load(&config_path)
+        .expect("config saved");
+    assert_eq!(saved.use_username_dirs, Some(true));
+}
+
 /// The account block answers "who is this session, and what is it
 /// offering" without a trip to another screen.
 #[test]