feat: browse the highlighted transfer's user with b

In the Downloads / Uploads pane, b now opens the share of whoever owns
the selected download or upload, the way it already browses the owner of
a highlighted result. With no row selected it still prompts.

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

@@ -206,6 +206,21 @@ impl MainTui {
         self.state.results_selected_indices.clear();
     }
 
+    /// The user behind the highlighted transfer, download or upload.
+    pub(super) fn selected_transfer_user(&self) -> Option<String> {
+        match selected_transfer(
+            self.state.downloads_table_state.selected(),
+            &self.state.downloads,
+            &self.state.uploads,
+        ) {
+            Some(InfoSubject::Download(entry)) => {
+                Some(entry.download.username.clone())
+            }
+            Some(InfoSubject::Upload(upload)) => Some(upload.username.clone()),
+            Some(InfoSubject::Result(_)) | None => None,
+        }
+    }
+
     pub(super) fn cancel_selected_transfer(&self) {
         let selected = selected_transfer(
             self.state.downloads_table_state.selected(),

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

@@ -151,6 +151,10 @@ impl MainTui {
                     && let Some(owner) = self.highlighted_result_owner()
                 {
                     self.start_browse(owner);
+                } else if self.state.focused_pane == FocusedPane::Downloads
+                    && let Some(user) = self.selected_transfer_user()
+                {
+                    self.start_browse(user);
                 } else {
                     self.state.command_bar_active = true;
                     self.state.command_bar_mode = CommandBarMode::Browse;

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

@@ -310,6 +310,20 @@ mod tests {
         at_status(username, filename, soulseek_rs::DownloadStatus::Completed)
     }
 
+    fn uploading(
+        username: &str,
+        filename: &str,
+    ) -> soulseek_rs::types::UploadInfo {
+        soulseek_rs::types::UploadInfo {
+            username: username.to_string(),
+            filename: filename.to_string(),
+            size: 10,
+            bytes_sent: 1,
+            speed_bytes_per_sec: 1.0,
+            status: soulseek_rs::types::UploadStatus::InProgress,
+        }
+    }
+
     fn at_status(
         username: &str,
         filename: &str,
@@ -654,14 +668,7 @@ mod tests {
             download: queued("bob", "song.mp3"),
             receiver: None,
         });
-        tui.state.uploads.push(soulseek_rs::types::UploadInfo {
-            username: "alice".to_string(),
-            filename: "served.mp3".to_string(),
-            size: 10,
-            bytes_sent: 1,
-            speed_bytes_per_sec: 1.0,
-            status: soulseek_rs::types::UploadStatus::InProgress,
-        });
+        tui.state.uploads.push(uploading("alice", "served.mp3"));
         tui.state.downloads_table_state.select(Some(1));
         tui.state.focused_pane = FocusedPane::Downloads;
 
@@ -677,6 +684,45 @@ mod tests {
         );
     }
 
+    #[test]
+    fn b_browses_the_user_of_the_highlighted_download() {
+        let mut tui = with_session(TalkativeSession::default());
+        tui.state.downloads.push(crate::models::DownloadEntry {
+            download: queued("bob", "song.mp3"),
+            receiver: None,
+        });
+        tui.state.downloads_table_state.select(Some(0));
+        tui.state.focused_pane = FocusedPane::Downloads;
+
+        tui.handle_key_event(key('b'));
+
+        assert!(tui.state.show_browse, "the browse popup opens");
+        assert_eq!(
+            tui.state.browse.active_tab().map(|b| b.username.as_str()),
+            Some("bob"),
+            "the download's user is the one browsed"
+        );
+        assert!(
+            !tui.state.command_bar_active,
+            "b on a transfer goes straight to the user, not the prompt"
+        );
+    }
+
+    #[test]
+    fn b_on_an_upload_row_browses_that_user() {
+        let mut tui = with_session(TalkativeSession::default());
+        tui.state.uploads.push(uploading("alice", "served.mp3"));
+        tui.state.downloads_table_state.select(Some(0));
+        tui.state.focused_pane = FocusedPane::Downloads;
+
+        tui.handle_key_event(key('b'));
+
+        assert_eq!(
+            tui.state.browse.active_tab().map(|b| b.username.as_str()),
+            Some("alice")
+        );
+    }
+
     fn with_session(session: TalkativeSession) -> MainTui {
         attach(Arc::new(session))
     }
@@ -1591,9 +1637,11 @@ mod tests {
         let screen = screen_sized(&mut tui, 80, 24);
         assert!(screen.contains("Tab / Shift-Tab"), "{screen}");
 
-        // A wide window shows both columns at once, nothing to scroll.
+        // A wide window shows both columns at once, nothing to scroll. It
+        // has to be tall enough to hold the taller column outright; in a
+        // shorter one End follows the tail and the headings scroll off.
         press(&mut tui, KeyCode::End);
-        let screen = screen_of(&mut tui);
+        let screen = screen_sized(&mut tui, 160, 44);
         let panes = row_with(&screen, "Panes");
         assert!(panes.contains("Searches"), "two columns: {panes}");
         assert!(screen.contains("Tab / Shift-Tab"), "{screen}");

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

@@ -89,6 +89,7 @@ const HELP_RIGHT: &[(&str, &[(&str, &str)])] = &[
             ("r", "retry a failed one"),
             ("d", "delete a queued or finished one"),
             ("c", "clear every finished one"),
+            ("b", "browse that user"),
         ],
     ),
     (