chore(coding-agent): add startup onboarding hint (#2620)

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -462,7 +462,11 @@ export class InteractiveMode {
 				hint("app.clipboard.pasteImage", "to paste image"),
 				rawKeyHint("drop files", "to attach"),
 			].join("\n");
-			this.builtInHeader = new Text(`${logo}\n${instructions}`, 1, 0);
+			const onboarding = theme.fg(
+				"dim",
+				`Pi can explain its own features and look up its docs. Ask it how to use or extend Pi.`,
+			);
+			this.builtInHeader = new Text(`${logo}\n${instructions}\n\n${onboarding}`, 1, 0);
 
 			// Setup UI layout
 			this.headerContainer.addChild(new Spacer(1));