fix(config): apply $production/$development layers when NODE_ENV is unset

src/config/loader.ts

@@ -79,6 +79,7 @@ async function _loadUserConfig(
   let preset: string | undefined = (configOverrides.preset as string) || process.env.NITRO_PRESET || process.env.SERVER_PRESET
 
   const _dotenv = opts.dotenv ?? (configOverrides.dev && { fileName: [".env", ".env.local"] });
+  const envName = opts.c12?.envName ?? (configOverrides.dev ? "development" : "production");
   const loadedConfig = await (
     opts.watch
       ? watchConfig<NitroConfig & { _meta?: NitroPresetMeta }>
@@ -87,6 +88,7 @@ async function _loadUserConfig(
     name: "nitro",
     cwd: configOverrides.rootDir,
     dotenv: _dotenv,
+    envName,
     extend: { extendKey: ["extends", "preset"] },
     defaults: NitroDefaults,
     async overrides({ rawConfigs }) {

test/unit/config-loader-env.test.ts

@@ -0,0 +1,74 @@
+import { mkdtemp, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "pathe";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("nitro/meta", () => ({
+  version: "0.0.0-test",
+  runtimeDir: "/tmp",
+  presetsDir: "/tmp",
+  pkgDir: "/tmp",
+  runtimeDependencies: [],
+}));
+
+const originalNodeEnv = process.env.NODE_ENV;
+const tempDirs: string[] = [];
+
+async function createFixtureConfig() {
+  const rootDir = await mkdtemp(join(tmpdir(), "nitro-config-env-"));
+  tempDirs.push(rootDir);
+
+  await writeFile(
+    join(rootDir, "nitro.config.ts"),
+    `export default defineNitroConfig({
+  preset: 'node-server',
+  routeRules: {
+    '/base': { headers: { 'x-env': 'base' } }
+  },
+  $production: {
+    routeRules: {
+      '/prod': { headers: { 'x-env': 'production' } }
+    }
+  },
+  $development: {
+    routeRules: {
+      '/dev': { headers: { 'x-env': 'development' } }
+    }
+  }
+})
+`
+  );
+
+  return rootDir;
+}
+
+afterEach(async () => {
+  process.env.NODE_ENV = originalNodeEnv;
+  for (const dir of tempDirs.splice(0, tempDirs.length)) {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+describe("config loader env layers", () => {
+  it("applies $production when NODE_ENV is unset and dev=false", async () => {
+    delete process.env.NODE_ENV;
+    const rootDir = await createFixtureConfig();
+
+    const { loadOptions } = await import("../../src/config/loader.ts");
+    const options = await loadOptions({ rootDir, dev: false });
+
+    expect(options.routeRules["/prod"]?.headers?.["x-env"]).toBe("production");
+    expect(options.routeRules["/dev"]).toBeUndefined();
+  });
+
+  it("applies $development when NODE_ENV is unset and dev=true", async () => {
+    delete process.env.NODE_ENV;
+    const rootDir = await createFixtureConfig();
+
+    const { loadOptions } = await import("../../src/config/loader.ts");
+    const options = await loadOptions({ rootDir, dev: true });
+
+    expect(options.routeRules["/dev"]?.headers?.["x-env"]).toBe("development");
+    expect(options.routeRules["/prod"]).toBeUndefined();
+  });
+});