fix(desktop): stop looping on an update that never installs (#2879)

fluxer_desktop/src/main/UpdaterApplyState.ts

@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import fs from 'node:fs';
+import path from 'node:path';
+import {app} from 'electron';
+import log from 'electron-log';
+
+const APPLY_STATE_FILE_NAME = 'update-apply-state.json';
+
+export type VelopackApplyAttempt = {
+	version: string;
+	attemptedAt: number;
+};
+
+function getApplyStatePath(): string {
+	return path.join(app.getPath('userData'), APPLY_STATE_FILE_NAME);
+}
+
+export function readVelopackApplyAttempt(): VelopackApplyAttempt | null {
+	let raw: string;
+	try {
+		raw = fs.readFileSync(getApplyStatePath(), 'utf8');
+	} catch {
+		return null;
+	}
+	try {
+		const parsed = JSON.parse(raw) as {version?: unknown; attemptedAt?: unknown};
+		if (typeof parsed.version !== 'string' || parsed.version.length === 0) {
+			return null;
+		}
+		return {
+			version: parsed.version,
+			attemptedAt: typeof parsed.attemptedAt === 'number' ? parsed.attemptedAt : 0,
+		};
+	} catch (error) {
+		log.warn('Failed to parse the recorded update apply attempt', error);
+		return null;
+	}
+}
+
+export function recordVelopackApplyAttempt(version: string): void {
+	const payload: VelopackApplyAttempt = {version, attemptedAt: Date.now()};
+	try {
+		fs.writeFileSync(getApplyStatePath(), JSON.stringify(payload), 'utf8');
+	} catch (error) {
+		log.warn('Failed to record the update apply attempt', error);
+	}
+}
+
+export function clearVelopackApplyAttempt(): void {
+	try {
+		fs.rmSync(getApplyStatePath(), {force: true});
+	} catch (error) {
+		log.warn('Failed to clear the recorded update apply attempt', error);
+	}
+}