fix(coding-agent): keep one copy of each rendered user message line

The user message's Markdown pads and colors its own background instead of
sitting in a Box that kept a second full-width copy of every line. The output
is identical.

packages/coding-agent/CHANGELOG.md

@@ -17,6 +17,7 @@
 - Fixed the sign-in URL printed by `/mcp login` not being clickable when it wraps ([#10186](https://github.com/earendil-works/pi/issues/10186)).
 - Fixed `--provider` without `--model` being silently ignored and running the default model from another provider; it now fails with an error ([#10236](https://github.com/earendil-works/pi/issues/10236)).
 - Fixed MCP servers that ask for more scope (`insufficient_scope`) requesting sign-in over and over. The new sign-in requested only the missing scopes, so the new token lost access the previous one had; it now keeps the granted scopes.
+- Fixed user messages in the transcript keeping two full-width copies of every rendered line; they keep one, with identical output.
 
 ## [0.99.2] - 2026-09-30
 

packages/coding-agent/src/modes/interactive/components/user-message.ts

@@ -1,4 +1,4 @@
-import { Box, Container, Markdown, type MarkdownTheme } from "@earendil-works/pi-tui";
+import { Container, Markdown, type MarkdownTheme } from "@earendil-works/pi-tui";
 import type { MarkdownTransformer } from "../../../core/extensions/types.ts";
 import { getMarkdownTheme, theme } from "../theme/theme.ts";
 import { createMarkdownTransform } from "./markdown-transform.ts";
@@ -37,15 +37,17 @@ export class UserMessageComponent extends Container {
 
 	private rebuild(): void {
 		this.clear();
-		const contentBox = new Box(this.outputPad, 1, (content: string) => theme.bg("userMessageBg", content));
-		contentBox.addChild(
+		// The Markdown pads and colors its own background: a Box around it would keep a second full-width copy of every
+		// line, with identical output.
+		this.addChild(
 			new Markdown(
 				this.text,
-				0,
-				0,
+				this.outputPad,
+				1,
 				this.markdownTheme,
 				{
 					color: (content: string) => theme.fg("userMessageText", content),
+					bgColor: (content: string) => theme.bg("userMessageBg", content),
 				},
 				{
 					preserveOrderedListMarkers: true,
@@ -54,7 +56,6 @@ export class UserMessageComponent extends Container {
 				},
 			),
 		);
-		this.addChild(contentBox);
 	}
 
 	override render(width: number): string[] {