Add healthcheck for client

frontend/local-client-cli/src/healthcheck.ts

@@ -0,0 +1,59 @@
+#!/usr/bin/env node
+
+/**
+ * Healthcheck script for Docker container
+ * Checks if the sync client is connected to the server
+ */
+
+import * as fs from "fs";
+import type { NetworkConnectionStatus } from "sync-client";
+
+function isHealthStatus(value: unknown): value is NetworkConnectionStatus {
+	if (typeof value !== "object" || value === null) {
+		return false;
+	}
+
+	return true;
+}
+
+function main(): void {
+	if (process.argv.length < 3) {
+		console.error("Usage: healthcheck <path-to-health-file>");
+		process.exit(1);
+	}
+	const [, , healthFile] = process.argv;
+
+	try {
+		// Check if health file exists
+		if (!fs.existsSync(healthFile)) {
+			console.error(`Health file does not exist: ${healthFile}`);
+			process.exit(1);
+		}
+
+		// Read and parse health status
+		const content = fs.readFileSync(healthFile, "utf-8");
+		const parsed: unknown = JSON.parse(content);
+
+		// Validate the parsed object using type guard
+		if (!isHealthStatus(parsed)) {
+			throw new Error("Invalid health status format");
+		}
+
+		const status = parsed;
+
+		if (!status.isSuccessful || !status.isWebSocketConnected) {
+			console.error("Not connected to server: " + status.serverMessage);
+			process.exit(1);
+		}
+
+		console.log("Healthy: Connected to server");
+		process.exit(0);
+	} catch (error) {
+		console.error(
+			`Health check failed: ${error instanceof Error ? error.message : String(error)}`
+		);
+		process.exit(1);
+	}
+}
+
+main();