Fix Windows terminal background rendering and add /debug command

- Strip carriage return characters from bash tool output to fix background padding on Windows
- Add hidden /debug command to write rendered lines to debug log for TUI debugging
- Document /debug command in README.md development section

packages/coding-agent/README.md

@@ -1156,6 +1156,19 @@ import { getPackageDir, getThemeDir, getPackageJsonPath, getReadmePath, getChang
 
 **Never use `__dirname` directly** for resolving package assets. The `paths.ts` module handles the differences between execution modes automatically.
 
+### Debug Command
+
+The `/debug` command is a hidden development feature (not shown in autocomplete) that writes all currently rendered lines with their visible widths and ANSI escape sequences to `~/.pi/agent/pi-debug.log`. This is useful for debugging TUI rendering issues, especially when lines don't extend to the terminal edge or contain unexpected invisible characters.
+
+```
+/debug
+```
+
+The debug log includes:
+- Terminal width at time of capture
+- Total number of rendered lines
+- Each line with its index, visible width, and JSON-escaped content showing all ANSI codes
+
 ## License
 
 MIT

packages/coding-agent/src/tui/tool-execution.ts

@@ -83,8 +83,9 @@ export class ToolExecutionComponent extends Container {
 		const textBlocks = this.result.content?.filter((c: any) => c.type === "text") || [];
 		const imageBlocks = this.result.content?.filter((c: any) => c.type === "image") || [];
 
-		// Strip ANSI codes from raw output (bash may emit colors/formatting)
-		let output = textBlocks.map((c: any) => stripAnsi(c.text || "")).join("\n");
+		// Strip ANSI codes and carriage returns from raw output
+		// (bash may emit colors/formatting, and Windows may include \r)
+		let output = textBlocks.map((c: any) => stripAnsi(c.text || "").replace(/\r/g, "")).join("\n");
 
 		// Add indicator for images
 		if (imageBlocks.length > 0) {

packages/coding-agent/src/tui/tui-renderer.ts

@@ -1,3 +1,6 @@
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
 import type { Agent, AgentEvent, AgentState, ThinkingLevel } from "@mariozechner/pi-agent-core";
 import type { AssistantMessage, Message, Model } from "@mariozechner/pi-ai";
 import type { SlashCommand } from "@mariozechner/pi-tui";
@@ -12,8 +15,8 @@ import {
 	Text,
 	TruncatedText,
 	TUI,
+	visibleWidth,
 } from "@mariozechner/pi-tui";
-
 import { exec } from "child_process";
 import { getChangelogPath, parseChangelog } from "../changelog.js";
 import { exportSessionToHtml } from "../export-html.js";
@@ -415,6 +418,13 @@ export class TuiRenderer {
 				return;
 			}
 
+			// Check for /debug command
+			if (text === "/debug") {
+				this.handleDebugCommand();
+				this.editor.setText("");
+				return;
+			}
+
 			// Check for file-based slash commands
 			text = expandSlashCommand(text, this.fileCommands);
 
@@ -1530,6 +1540,42 @@ export class TuiRenderer {
 		this.ui.requestRender();
 	}
 
+	private handleDebugCommand(): void {
+		// Force a render and capture all lines with their widths
+		const width = (this.ui as any).terminal.columns;
+		const allLines = this.ui.render(width);
+
+		const debugLogPath = path.join(os.homedir(), ".pi", "agent", "pi-debug.log");
+		const debugData = [
+			`Debug output at ${new Date().toISOString()}`,
+			`Terminal width: ${width}`,
+			`Total lines: ${allLines.length}`,
+			"",
+			"=== All rendered lines with visible widths ===",
+			...allLines.map((line, idx) => {
+				const vw = visibleWidth(line);
+				const escaped = JSON.stringify(line);
+				return `[${idx}] (w=${vw}) ${escaped}`;
+			}),
+			"",
+		].join("\n");
+
+		fs.mkdirSync(path.dirname(debugLogPath), { recursive: true });
+		fs.writeFileSync(debugLogPath, debugData);
+
+		// Show confirmation
+		this.chatContainer.addChild(new Spacer(1));
+		this.chatContainer.addChild(
+			new Text(
+				theme.fg("accent", "✓ Debug log written") + "\n" + theme.fg("muted", `~/.pi/agent/pi-debug.log`),
+				1,
+				1,
+			),
+		);
+
+		this.ui.requestRender();
+	}
+
 	private updatePendingMessagesDisplay(): void {
 		this.pendingMessagesContainer.clear();