feat(coding-agent): allow hiding working loader

closes #3674

packages/coding-agent/docs/extensions.md

@@ -2070,7 +2070,7 @@ Extensions can interact with users via `ctx.ui` methods and customize how messag
 - Async operations with cancel (BorderedLoader)
 - Settings toggles (SettingsList)
 - Status indicators (setStatus)
-- Working message and indicator during streaming (`setWorkingMessage`, `setWorkingIndicator`)
+- Working message, visibility, and indicator during streaming (`setWorkingMessage`, `setWorkingVisible`, `setWorkingIndicator`)
 - Widgets above/below editor (setWidget)
 - Autocomplete providers layered on top of built-in slash/path completion (addAutocompleteProvider)
 - Custom footers (setFooter)
@@ -2152,9 +2152,11 @@ See [examples/extensions/timed-confirm.ts](../examples/extensions/timed-confirm.
 ctx.ui.setStatus("my-ext", "Processing...");
 ctx.ui.setStatus("my-ext", undefined);  // Clear
 
-// Working message (shown during streaming)
+// Working loader (shown during streaming)
 ctx.ui.setWorkingMessage("Thinking deeply...");
 ctx.ui.setWorkingMessage();  // Restore default
+ctx.ui.setWorkingVisible(false);  // Hide the built-in working loader row entirely
+ctx.ui.setWorkingVisible(true);   // Show the built-in working loader row
 
 // Working indicator (shown during streaming)
 ctx.ui.setWorkingIndicator({ frames: [ctx.ui.theme.fg("accent", "●")] });  // Static dot