fix(coding-agent): avoid full redraw on large edit results closes #2664

packages/coding-agent/test/edit-tool-no-full-redraw.test.ts

@@ -0,0 +1,126 @@
+import { mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { Container, type Terminal, Text, TUI } from "@mariozechner/pi-tui";
+import { afterEach, beforeAll, describe, expect, it } from "vitest";
+import { createEditToolDefinition } from "../src/core/tools/edit.js";
+import { computeEditsDiff, type Edit } from "../src/core/tools/edit-diff.js";
+import { ToolExecutionComponent } from "../src/modes/interactive/components/tool-execution.js";
+import { initTheme } from "../src/modes/interactive/theme/theme.js";
+
+class FakeTerminal implements Terminal {
+	columns = 80;
+	rows = 24;
+	kittyProtocolActive = true;
+	writes: string[] = [];
+
+	start(): void {}
+	stop(): void {}
+	async drainInput(): Promise<void> {}
+	write(data: string): void {
+		this.writes.push(data);
+	}
+	moveBy(_lines: number): void {}
+	hideCursor(): void {}
+	showCursor(): void {}
+	clearLine(): void {}
+	clearFromCursor(): void {}
+	clearScreen(): void {}
+	setTitle(_title: string): void {}
+
+	get fullClearCount(): number {
+		return this.writes.filter((write) => write.includes("\x1b[2J\x1b[H\x1b[3J")).length;
+	}
+}
+
+async function waitForRender(): Promise<void> {
+	await new Promise((resolve) => setTimeout(resolve, 0));
+}
+
+function createLargeEdits(lines: string[]): Edit[] {
+	const targets = [50, 150, 250, 350, 450, 550, 650, 750, 850, 950];
+	return targets.map((lineNumber) => ({
+		oldText: `${lines[lineNumber - 1]}\n${lines[lineNumber]}\n${lines[lineNumber + 1]}`,
+		newText: `${lines[lineNumber - 1]}\n${lines[lineNumber]} changed\n${lines[lineNumber + 1]}`,
+	}));
+}
+
+describe("edit tool TUI rendering", () => {
+	const tempDirs: string[] = [];
+
+	beforeAll(() => {
+		initTheme("dark");
+	});
+
+	afterEach(async () => {
+		await Promise.all(tempDirs.splice(0).map((dir) => rm(dir, { recursive: true, force: true })));
+	});
+
+	it("renders the large diff only in the settled result without triggering a full TUI redraw", async () => {
+		const dir = await mkdtemp(join(tmpdir(), "pi-edit-redraw-"));
+		tempDirs.push(dir);
+		const filePath = join(dir, "large-edit.txt");
+		await writeFile(
+			filePath,
+			`${Array.from({ length: 1000 }, (_, i) => `line ${i}`).join("\n")}
+`,
+			"utf8",
+		);
+		const lines = (await readFile(filePath, "utf8")).trimEnd().split("\n");
+		const edits = createLargeEdits(lines);
+		const diff = await computeEditsDiff(filePath, edits, process.cwd());
+		if ("error" in diff) {
+			throw new Error(diff.error);
+		}
+
+		const terminal = new FakeTerminal();
+		const tui = new TUI(terminal);
+		const root = new Container();
+		for (let i = 0; i < 200; i++) {
+			root.addChild(new Text(`history ${i}`, 0, 0));
+		}
+
+		const component = new ToolExecutionComponent(
+			"edit",
+			"tool-call-1",
+			{ path: filePath, edits },
+			{},
+			createEditToolDefinition(process.cwd()),
+			tui,
+			process.cwd(),
+		);
+		root.addChild(component);
+		tui.addChild(root);
+		tui.start();
+		await waitForRender();
+
+		component.setArgsComplete();
+		tui.requestRender();
+		await waitForRender();
+
+		const callOnlyRender = component.render(80).join("\n");
+		expect(callOnlyRender).toContain("edit");
+		expect(callOnlyRender).not.toContain("line 50 changed");
+		expect(callOnlyRender).not.toContain("+  51");
+
+		const redrawsBeforeResult = tui.fullRedraws;
+		const clearsBeforeResult = terminal.fullClearCount;
+		component.updateResult(
+			{
+				content: [{ type: "text", text: `Successfully replaced ${edits.length} block(s) in ${filePath}.` }],
+				details: diff,
+				isError: false,
+			},
+			false,
+		);
+		tui.requestRender();
+		await waitForRender();
+
+		expect(tui.fullRedraws).toBe(redrawsBeforeResult);
+		expect(terminal.fullClearCount).toBe(clearsBeforeResult);
+
+		const settledRender = component.render(80).join("\n");
+		expect(settledRender).toContain("line 50 changed");
+		expect(settledRender).toContain("line 950 changed");
+	});
+});