feat: add visual selection indicator in TUI workspace list

When selecting workspaces via Space key, rows now display a visible
indicator (◆) with bold cyan styling. The current workspace indicator
(→) is preserved and both are shown when a workspace is both selected
and current (◆ →).

Uses Rich Text objects for cell styling via Textual's DataTable API.

Closes agentspaces-4ok

Author: ckrough

src/agentspaces/ui/app.py

@@ -169,10 +169,17 @@ def action_toggle_select(self) -> None:
         if cursor_row < 0 or cursor_row >= len(self.workspaces):
             return
 
+        workspace = self.workspaces[cursor_row]
+        is_current = str(workspace.path) == self.current_path
+
         if cursor_row in self.selected_rows:
             self.selected_rows.remove(cursor_row)
+            table.set_row_selected(
+                workspace.name, selected=False, is_current=is_current
+            )
         else:
             self.selected_rows.add(cursor_row)
+            table.set_row_selected(workspace.name, selected=True, is_current=is_current)
 
         # Visual feedback
         self.notify(f"Selected: {len(self.selected_rows)} workspace(s)")

src/agentspaces/ui/widgets.py

@@ -2,8 +2,10 @@
 
 from __future__ import annotations
 
+import contextlib
 from typing import TYPE_CHECKING
 
+from rich.text import Text
 from textual.containers import Container, Horizontal
 from textual.screen import ModalScreen
 from textual.widgets import (
@@ -60,21 +62,55 @@ def load_workspaces(
 
         for workspace in workspaces:
             # Visual indicators
-            name_display = workspace.name
-            if current_path and str(workspace.path) == current_path:
-                name_display = f"→ {name_display}"
+            is_current = current_path and str(workspace.path) == current_path
+            if is_current:
+                name_display = Text(f"→ {workspace.name}")
+            else:
+                name_display = Text(workspace.name)
 
             venv_display = "✓" if workspace.has_venv else ""
             purpose_display = self._truncate(workspace.purpose or "", 38)
 
+            # DataTable supports Rich renderables per Textual docs
             self.add_row(
-                name_display,
+                name_display,  # type: ignore[arg-type]
                 workspace.branch,
                 purpose_display,
                 venv_display,
                 key=workspace.name,
             )
 
+    def set_row_selected(
+        self, row_key: str, selected: bool, is_current: bool = False
+    ) -> None:
+        """Update row display to show selection state.
+
+        Args:
+            row_key: The row key (workspace name) to update.
+            selected: Whether the row is selected.
+            is_current: Whether this is the current workspace.
+        """
+        # Build display name with indicators
+        # Show both indicators when both conditions apply
+        prefix = ""
+        if is_current:
+            prefix = "→ "
+        if selected:
+            prefix = "◆ " + prefix  # "◆ → " when both selected and current
+
+        display_name = f"{prefix}{row_key}"
+
+        # Style selected rows distinctly
+        if selected:
+            styled = Text(display_name, style="bold cyan")
+        else:
+            styled = Text(display_name)
+
+        # DataTable supports Rich renderables per Textual docs
+        # Suppress KeyError if row was removed between toggle and update
+        with contextlib.suppress(KeyError):
+            self.update_cell(row_key, "name", styled)  # type: ignore[arg-type]
+
     @staticmethod
     def _truncate(text: str, max_length: int) -> str:
         """Truncate text with ellipsis if too long."""