fix(coding-agent): bound compaction status width

packages/coding-agent/src/modes/interactive/changes.md

@@ -1,5 +1,23 @@
 # changes
 
+## bounded compaction progress row (2026-07-24)
+
+### What changed
+
+- `components/status-indicator.ts`: the combined compaction spinner, status, and streamed preview is truncated to the
+  actual terminal width.
+- `../../../test/interactive-mode-compaction.test.ts`: pins a hostile multiline, 600-column progress update to one
+  rendered row no wider than the requested terminal width.
+
+### Why
+
+- Long streamed summaries could wrap the otherwise single-row lifecycle indicator, push the composer upward, and make
+  previous output appear erased as the terminal viewport remapped.
+
+### Expected merge conflict zones
+
+- LOW: `components/status-indicator.ts` compaction progress rendering.
+
 ## accepted-only compaction queue transfer (2026-07-24)
 
 ### What changed

packages/coding-agent/src/modes/interactive/components/status-indicator.ts

@@ -1,4 +1,11 @@
-import { type Component, Loader, type LoaderIndicatorOptions, type TUI } from "@earendil-works/pi-tui";
+import {
+	type Component,
+	Loader,
+	type LoaderIndicatorOptions,
+	type TUI,
+	truncateToWidth,
+	visibleWidth,
+} from "@earendil-works/pi-tui";
 import { theme } from "../theme/theme.ts";
 import { CountdownTimer } from "./countdown-timer.ts";
 import { keyText } from "./keybinding-hints.ts";
@@ -105,9 +112,12 @@ export class CompactionStatusIndicator extends StatusIndicator {
 	}
 
 	override render(width: number): string[] {
-		const status = super.render(width).join(" ");
-		if (!this.progressText) return [status];
-		return [`${status} ${theme.fg("muted", this.progressText)}`];
+		if (!this.progressText) return super.render(width);
+		const progressWidth = Math.min(visibleWidth(this.progressText), Math.max(1, Math.floor(width / 2)));
+		const statusWidth = Math.max(1, width - progressWidth - 1);
+		const status = truncateToWidth(super.render(statusWidth).join(" "), statusWidth, "");
+		const progress = truncateToWidth(theme.fg("muted", this.progressText), progressWidth);
+		return [truncateToWidth(`${status} ${progress}`, width)];
 	}
 }
 

packages/coding-agent/test/interactive-mode-compaction.test.ts

@@ -1,7 +1,7 @@
 import { mkdtempSync, readFileSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
-import { Container, sanitizeTerminalLabel } from "@earendil-works/pi-tui";
+import { Container, sanitizeTerminalLabel, visibleWidth } from "@earendil-works/pi-tui";
 import { beforeAll, describe, expect, test, vi } from "vitest";
 import { SessionManager } from "../src/core/session-manager.ts";
 import { CompactionSummaryMessageComponent } from "../src/modes/interactive/components/compaction-summary-message.ts";
@@ -97,7 +97,7 @@ describe("InteractiveMode compaction events", () => {
 		fakeThis.autoCompactionLoader?.stop();
 	});
 
-	test("renders streamed compaction progress below the active loader", async () => {
+	test("bounds streamed compaction progress to the active status row", async () => {
 		const statusContainer = new Container();
 		const fakeThis = {
 			isInitialized: true,
@@ -133,12 +133,15 @@ describe("InteractiveMode compaction events", () => {
 		await handleEvent.call(fakeThis, {
 			type: "compaction_progress",
 			reason: "extension",
-			delta: "live summary chunk",
+			delta: `live\n${"summary chunk ".repeat(40)}`,
 		});
 
-		const rendered = stripAnsi(statusContainer.children.flatMap((child) => child.render(120)).join("\n"));
-		expect(rendered).toContain("Compacting context");
-		expect(rendered).toContain("live summary chunk");
+		const renderedLines = statusContainer.children.flatMap((child) => child.render(40));
+		const rendered = stripAnsi(renderedLines.join("\n"));
+		expect(renderedLines).toHaveLength(1);
+		expect(visibleWidth(renderedLines[0] ?? "")).toBeLessThanOrEqual(40);
+		expect(rendered).toContain("Compacting");
+		expect(rendered).toContain("live summary");
 
 		fakeThis.autoCompactionLoader?.stop();
 	});