fix: add automatic deployment skew protection

next.config.ts

@@ -1,8 +1,23 @@
+import { execFileSync } from "node:child_process";
 import withBundleAnalyzer from "@next/bundle-analyzer";
 import { withSentryConfig } from "@sentry/nextjs";
 import type { NextConfig } from "next";
 import createNextIntlPlugin from "next-intl/plugin";
 
+function resolveDeploymentId(): string | undefined {
+	const configuredId = process.env.NEXT_DEPLOYMENT_ID?.trim();
+	if (configuredId) return configuredId;
+
+	try {
+		return execFileSync("git", ["rev-parse", "HEAD"], {
+			encoding: "utf8",
+			stdio: ["ignore", "pipe", "ignore"],
+		}).trim();
+	} catch {
+		return process.env.APP_VERSION?.trim() || undefined;
+	}
+}
+
 const securityHeaders = [
 	{ key: "X-DNS-Prefetch-Control", value: "on" },
 	{
@@ -20,6 +35,7 @@ const securityHeaders = [
 ];
 
 const nextConfig: NextConfig = {
+	deploymentId: resolveDeploymentId(),
 	turbopack: {},
 	serverExternalPackages: ["mariadb", "lzma", "sharp", "pino", "pino-pretty"],
 

src/lib/deployment-id.test.ts

@@ -0,0 +1,15 @@
+import { execFileSync } from "node:child_process";
+import { describe, expect, it } from "vitest";
+import nextConfig from "../../next.config";
+
+describe("deployment version skew protection", () => {
+	it("uses an explicit deployment ID or the current Git commit", () => {
+		const gitCommit = execFileSync("git", ["rev-parse", "HEAD"], {
+			encoding: "utf8",
+		}).trim();
+
+		expect(nextConfig.deploymentId).toBe(
+			process.env.NEXT_DEPLOYMENT_ID?.trim() || gitCommit,
+		);
+	});
+});