feat(coding-agent): add configurable working indicator closes #3413

packages/coding-agent/docs/tui.md

@@ -735,6 +735,31 @@ ctx.ui.setStatus("my-ext", undefined);
 
 **Examples:** [status-line.ts](../examples/extensions/status-line.ts), [plan-mode.ts](../examples/extensions/plan-mode.ts), [preset.ts](../examples/extensions/preset.ts)
 
+### Pattern 4b: Working Indicator Customization
+
+Customize the inline working indicator shown while pi is streaming a response.
+
+```typescript
+// Static indicator
+ctx.ui.setWorkingIndicator({ frames: ["●"] });
+
+// Custom animated indicator
+ctx.ui.setWorkingIndicator({
+  frames: ["·", "•", "●", "•"],
+  intervalMs: 120,
+});
+
+// Hide the indicator entirely
+ctx.ui.setWorkingIndicator({ frames: [] });
+
+// Restore pi's default spinner
+ctx.ui.setWorkingIndicator();
+```
+
+This only affects the normal streaming working indicator. Compaction and retry loaders keep their built-in styling.
+
+**Examples:** [working-indicator.ts](../examples/extensions/working-indicator.ts)
+
 ### Pattern 5: Widgets Above/Below Editor
 
 Show persistent content above or below the input editor. Good for todo lists, progress.
@@ -881,6 +906,7 @@ export default function (pi: ExtensionAPI) {
 - **Async with cancel**: [examples/extensions/qna.ts](../examples/extensions/qna.ts) - BorderedLoader for LLM calls
 - **Settings toggles**: [examples/extensions/tools.ts](../examples/extensions/tools.ts) - SettingsList for tool enable/disable
 - **Status indicators**: [examples/extensions/plan-mode.ts](../examples/extensions/plan-mode.ts) - setStatus and setWidget
+- **Working indicator**: [examples/extensions/working-indicator.ts](../examples/extensions/working-indicator.ts) - setWorkingIndicator
 - **Custom footer**: [examples/extensions/custom-footer.ts](../examples/extensions/custom-footer.ts) - setFooter with stats
 - **Custom editor**: [examples/extensions/modal-editor.ts](../examples/extensions/modal-editor.ts) - Vim-like modal editing
 - **Snake game**: [examples/extensions/snake.ts](../examples/extensions/snake.ts) - Full game with keyboard input, game loop