diff --git a/.changeset/fifty-stingrays-flow.md b/.changeset/fifty-stingrays-flow.md
new file mode 100644
index 000000000000..3f4b96b04969
--- /dev/null
+++ b/.changeset/fifty-stingrays-flow.md
@@ -0,0 +1,6 @@
+---
+'astro': patch
+'@astrojs/db': patch
+---
+
+Refactors internally to use `node:util` `parseArgs` instead of `yargs-parser`
diff --git a/.changeset/rude-queens-shop.md b/.changeset/rude-queens-shop.md
new file mode 100644
index 000000000000..6610b16a5320
--- /dev/null
+++ b/.changeset/rude-queens-shop.md
@@ -0,0 +1,7 @@
+---
+'create-astro': patch
+'@astrojs/upgrade': patch
+---
+
+Refactors internally to use `node:util` `parseArgs` instead of `arg`
+
diff --git a/packages/astro/package.json b/packages/astro/package.json
index aaca3b8b0aa9..aaae869e51e3 100644
--- a/packages/astro/package.json
+++ b/packages/astro/package.json
@@ -181,7 +181,6 @@
     "vite": "^5.4.0",
     "vitefu": "^0.2.5",
     "which-pm": "^3.0.0",
-    "yargs-parser": "^21.1.1",
     "zod": "^3.23.8",
     "zod-to-json-schema": "^3.23.2"
   },
@@ -206,7 +205,6 @@
     "@types/js-yaml": "^4.0.9",
     "@types/prompts": "^2.4.9",
     "@types/semver": "^7.5.8",
-    "@types/yargs-parser": "^21.0.3",
     "astro-scripts": "workspace:*",
     "cheerio": "1.0.0",
     "eol": "^0.9.1",
diff --git a/packages/astro/performance/content-benchmark.mjs b/packages/astro/performance/content-benchmark.mjs
index a710bd762500..98ef5f0eac32 100644
--- a/packages/astro/performance/content-benchmark.mjs
+++ b/packages/astro/performance/content-benchmark.mjs
@@ -1,8 +1,8 @@
 /* eslint-disable no-console */
 
 import { fileURLToPath } from 'node:url';
+import { parseArgs } from 'node:util';
 import { bold, cyan, dim } from 'kleur/colors';
-import yargs from 'yargs-parser';
 import { loadFixture } from '../test/test-utils.js';
 import { generatePosts } from './scripts/generate-posts.mjs';
 
@@ -40,7 +40,7 @@ async function benchmark({ fixtures, templates, numPosts }) {
 // Test the build performance for content collections across multiple file types (md, mdx, mdoc)
 (async function benchmarkAll() {
 	try {
-		const flags = yargs(process.argv.slice(2));
+		const { values: flags } = parseArgs({ strict: false });
 		const test = Array.isArray(flags.test)
 			? flags.test
 			: typeof flags.test === 'string'
diff --git a/packages/astro/performance/package.json b/packages/astro/performance/package.json
index c0833b952288..36d62528176b 100644
--- a/packages/astro/performance/package.json
+++ b/packages/astro/performance/package.json
@@ -11,8 +11,6 @@
   "author": "",
   "license": "ISC",
   "devDependencies": {
-    "@types/yargs-parser": "^21.0.3",
-    "kleur": "^4.1.5",
-    "yargs-parser": "^21.1.1"
+    "kleur": "^4.1.5"
   }
 }
diff --git a/packages/astro/src/cli/add/index.ts b/packages/astro/src/cli/add/index.ts
index 7d33fe33a5be..f710184d2cb9 100644
--- a/packages/astro/src/cli/add/index.ts
+++ b/packages/astro/src/cli/add/index.ts
@@ -9,7 +9,6 @@ import ora from 'ora';
 import preferredPM from 'preferred-pm';
 import prompts from 'prompts';
 import maxSatisfying from 'semver/ranges/max-satisfying.js';
-import type yargs from 'yargs-parser';
 import {
 	loadTSConfig,
 	resolveConfig,
@@ -29,14 +28,14 @@ import { appendForwardSlash } from '../../core/path.js';
 import { apply as applyPolyfill } from '../../core/polyfill.js';
 import { ensureProcessNodeEnv, parseNpmName } from '../../core/util.js';
 import { eventCliSession, telemetry } from '../../events/index.js';
-import { createLoggerFromFlags, flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, createLoggerFromFlags, flagsToAstroInlineConfig } from '../flags.js';
 import { fetchPackageJson, fetchPackageVersions } from '../install-package.js';
 import { generate, parse, t, visit } from './babel.js';
 import { ensureImport } from './imports.js';
 import { wrapDefaultExport } from './wrapper.js';
 
 interface AddOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 interface IntegrationInfo {
@@ -143,7 +142,7 @@ export async function add(names: string[], { flags }: AddOptions) {
 	}
 
 	// Some packages might have a common alias! We normalize those here.
-	const cwd = flags.root;
+	const cwd = inlineConfig.root;
 	const logger = createLoggerFromFlags(flags);
 	const integrationNames = names.map((name) => (ALIASES.has(name) ? ALIASES.get(name)! : name));
 	const integrations = await validateIntegrations(integrationNames);
@@ -249,7 +248,7 @@ export async function add(names: string[], { flags }: AddOptions) {
 
 	const rawConfigPath = await resolveConfigPath({
 		root: rootPath,
-		configFile: flags.config,
+		configFile: inlineConfig.configFile,
 		fs: fsMod,
 	});
 	let configURL = rawConfigPath ? pathToFileURL(rawConfigPath) : undefined;
@@ -580,7 +579,7 @@ async function updateAstroConfig({
 }: {
 	configURL: URL;
 	ast: t.File;
-	flags: yargs.Arguments;
+	flags: Flags;
 	logger: Logger;
 	logAdapterInstructions: boolean;
 }): Promise<UpdateResult> {
@@ -717,7 +716,7 @@ async function tryToInstallIntegrations({
 }: {
 	integrations: IntegrationInfo[];
 	cwd?: string;
-	flags: yargs.Arguments;
+	flags: Flags;
 	logger: Logger;
 }): Promise<UpdateResult> {
 	const installCommand = await getInstallIntegrationsCommand({ integrations, cwd, logger });
@@ -893,7 +892,7 @@ async function updateTSConfig(
 	cwd = process.cwd(),
 	logger: Logger,
 	integrationsInfo: IntegrationInfo[],
-	flags: yargs.Arguments,
+	flags: Flags,
 ): Promise<UpdateResult> {
 	const integrations = integrationsInfo.map(
 		(integration) => integration.id as frameworkWithTSSettings,
@@ -996,7 +995,7 @@ function parseIntegrationName(spec: string) {
 	return { scope, name, tag };
 }
 
-async function askToContinue({ flags }: { flags: yargs.Arguments }): Promise<boolean> {
+async function askToContinue({ flags }: { flags: Flags }): Promise<boolean> {
 	if (flags.yes || flags.y) return true;
 
 	const response = await prompts({
@@ -1038,7 +1037,7 @@ function getDiffContent(input: string, output: string): string | null {
 async function setupIntegrationConfig(opts: {
 	root: URL;
 	logger: Logger;
-	flags: yargs.Arguments;
+	flags: Flags;
 	integrationName: string;
 	possibleConfigFiles: string[];
 	defaultConfigFile: string;
diff --git a/packages/astro/src/cli/build/index.ts b/packages/astro/src/cli/build/index.ts
index 15ff584317d9..9c10aff1569e 100644
--- a/packages/astro/src/cli/build/index.ts
+++ b/packages/astro/src/cli/build/index.ts
@@ -1,10 +1,9 @@
-import type yargs from 'yargs-parser';
 import _build from '../../core/build/index.js';
 import { printHelp } from '../../core/messages.js';
-import { flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, flagsToAstroInlineConfig } from '../flags.js';
 
 interface BuildOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 export async function build({ flags }: BuildOptions) {
@@ -25,5 +24,5 @@ export async function build({ flags }: BuildOptions) {
 
 	const inlineConfig = flagsToAstroInlineConfig(flags);
 
-	await _build(inlineConfig, { force: flags.force ?? false });
+	await _build(inlineConfig, { force: !!flags.force });
 }
diff --git a/packages/astro/src/cli/check/index.ts b/packages/astro/src/cli/check/index.ts
index a95e1074a59a..490d23970b51 100644
--- a/packages/astro/src/cli/check/index.ts
+++ b/packages/astro/src/cli/check/index.ts
@@ -1,13 +1,15 @@
 import path from 'node:path';
-import type { Arguments } from 'yargs-parser';
 import { ensureProcessNodeEnv } from '../../core/util.js';
-import { createLoggerFromFlags, flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, createLoggerFromFlags, flagsToAstroInlineConfig } from '../flags.js';
 import { getPackage } from '../install-package.js';
 
-export async function check(flags: Arguments) {
+export async function check(flags: Flags) {
 	ensureProcessNodeEnv('production');
 	const logger = createLoggerFromFlags(flags);
-	const getPackageOpts = { skipAsk: flags.yes || flags.y, cwd: flags.root };
+	const getPackageOpts = {
+		skipAsk: !!flags.yes || !!flags.y,
+		cwd: typeof flags.root == 'string' ? flags.root : undefined,
+	};
 	const checkPackage = await getPackage<typeof import('@astrojs/check')>(
 		'@astrojs/check',
 		logger,
diff --git a/packages/astro/src/cli/db/index.ts b/packages/astro/src/cli/db/index.ts
index dc6da36e1dff..c6be7411bb2a 100644
--- a/packages/astro/src/cli/db/index.ts
+++ b/packages/astro/src/cli/db/index.ts
@@ -1,18 +1,26 @@
-import type { Arguments } from 'yargs-parser';
 import type { AstroConfig } from '../../@types/astro.js';
 import { resolveConfig } from '../../core/config/config.js';
 import { apply as applyPolyfill } from '../../core/polyfill.js';
-import { createLoggerFromFlags, flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, createLoggerFromFlags, flagsToAstroInlineConfig } from '../flags.js';
 import { getPackage } from '../install-package.js';
 
+interface YargsArguments {
+	_: Array<string | number>;
+	'--'?: Array<string | number>;
+	[argName: string]: any;
+}
+
 type DBPackage = {
-	cli: (args: { flags: Arguments; config: AstroConfig }) => unknown;
+	cli: (args: { flags: YargsArguments; config: AstroConfig }) => unknown;
 };
 
-export async function db({ flags }: { flags: Arguments }) {
+export async function db({ positionals, flags }: { positionals: string[]; flags: Flags }) {
 	applyPolyfill();
 	const logger = createLoggerFromFlags(flags);
-	const getPackageOpts = { skipAsk: flags.yes || flags.y, cwd: flags.root };
+	const getPackageOpts = {
+		skipAsk: !!flags.yes || !!flags.y,
+		cwd: typeof flags.root == 'string' ? flags.root : undefined,
+	};
 	const dbPackage = await getPackage<DBPackage>('@astrojs/db', logger, getPackageOpts, []);
 
 	if (!dbPackage) {
@@ -27,5 +35,10 @@ export async function db({ flags }: { flags: Arguments }) {
 	const inlineConfig = flagsToAstroInlineConfig(flags);
 	const { astroConfig } = await resolveConfig(inlineConfig, 'build');
 
-	await cli({ flags, config: astroConfig });
+	const yargsArgs: YargsArguments = {
+		_: positionals,
+		...flags,
+	};
+
+	await cli({ flags: yargsArgs, config: astroConfig });
 }
diff --git a/packages/astro/src/cli/dev/index.ts b/packages/astro/src/cli/dev/index.ts
index 531cddde4ce9..2bd22b7c6aeb 100644
--- a/packages/astro/src/cli/dev/index.ts
+++ b/packages/astro/src/cli/dev/index.ts
@@ -1,11 +1,10 @@
 import { cyan } from 'kleur/colors';
-import type yargs from 'yargs-parser';
 import devServer from '../../core/dev/index.js';
 import { printHelp } from '../../core/messages.js';
-import { flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, flagsToAstroInlineConfig } from '../flags.js';
 
 interface DevOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 export async function dev({ flags }: DevOptions) {
diff --git a/packages/astro/src/cli/docs/index.ts b/packages/astro/src/cli/docs/index.ts
index cd6325577b37..afb5a1c622cf 100644
--- a/packages/astro/src/cli/docs/index.ts
+++ b/packages/astro/src/cli/docs/index.ts
@@ -1,9 +1,9 @@
-import type yargs from 'yargs-parser';
 import { printHelp } from '../../core/messages.js';
+import type { Flags } from '../flags.js';
 import { openInBrowser } from './open.js';
 
 interface DocsOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 export async function docs({ flags }: DocsOptions) {
diff --git a/packages/astro/src/cli/flags.ts b/packages/astro/src/cli/flags.ts
index 0af16806df44..c8180708f7a3 100644
--- a/packages/astro/src/cli/flags.ts
+++ b/packages/astro/src/cli/flags.ts
@@ -1,8 +1,11 @@
-import type { Arguments as Flags } from 'yargs-parser';
+import type { parseArgs } from 'node:util';
 import type { AstroInlineConfig } from '../@types/astro.js';
 import { type LogOptions, Logger } from '../core/logger/core.js';
 import { nodeLogDestination } from '../core/logger/node.js';
 
+export type ParsedArgsResult = ReturnType<typeof parseArgs>;
+export type Flags = ParsedArgsResult['values'];
+
 export function flagsToAstroInlineConfig(flags: Flags): AstroInlineConfig {
 	return {
 		// Inline-only configs
@@ -16,7 +19,7 @@ export function flagsToAstroInlineConfig(flags: Flags): AstroInlineConfig {
 		base: typeof flags.base === 'string' ? flags.base : undefined,
 		outDir: typeof flags.outDir === 'string' ? flags.outDir : undefined,
 		server: {
-			port: typeof flags.port === 'number' ? flags.port : undefined,
+			port: typeof flags.port === 'string' ? Number(flags.port) : undefined,
 			host:
 				typeof flags.host === 'string' || typeof flags.host === 'boolean' ? flags.host : undefined,
 			open:
diff --git a/packages/astro/src/cli/index.ts b/packages/astro/src/cli/index.ts
index 2d37132ac3b3..b3a819e586eb 100644
--- a/packages/astro/src/cli/index.ts
+++ b/packages/astro/src/cli/index.ts
@@ -1,7 +1,8 @@
+import { parseArgs } from 'node:util';
 /* eslint-disable no-console */
 import * as colors from 'kleur/colors';
-import yargs from 'yargs-parser';
 import { ASTRO_VERSION } from '../core/constants.js';
+import type { ParsedArgsResult } from './flags.js';
 
 type CLICommand =
 	| 'help'
@@ -65,9 +66,9 @@ function printVersion() {
 }
 
 /** Determine which command the user requested */
-function resolveCommand(flags: yargs.Arguments): CLICommand {
-	const cmd = flags._[2] as string;
-	if (flags.version) return 'version';
+function resolveCommand(args: ParsedArgsResult): CLICommand {
+	const cmd = args.positionals[2] as string;
+	if (args.values.version) return 'version';
 
 	const supportedCommands = new Set([
 		'add',
@@ -97,7 +98,9 @@ function resolveCommand(flags: yargs.Arguments): CLICommand {
  * NOTE: This function provides no error handling, so be sure
  * to present user-friendly error output where the fn is called.
  **/
-async function runCommand(cmd: string, flags: yargs.Arguments) {
+async function runCommand(cmd: string, args: ParsedArgsResult) {
+	const flags = args.values;
+
 	// These commands can run directly without parsing the user config.
 	switch (cmd) {
 		case 'help':
@@ -120,7 +123,7 @@ async function runCommand(cmd: string, flags: yargs.Arguments) {
 			// Do not track session start, since the user may be trying to enable,
 			// disable, or modify telemetry settings.
 			const { update } = await import('./telemetry/index.js');
-			const subcommand = flags._[3]?.toString();
+			const subcommand = args.positionals[3];
 			await update(subcommand, { flags });
 			return;
 		}
@@ -131,7 +134,7 @@ async function runCommand(cmd: string, flags: yargs.Arguments) {
 		}
 		case 'preferences': {
 			const { preferences } = await import('./preferences/index.js');
-			const [subcommand, key, value] = flags._.slice(3).map((v) => v.toString());
+			const [subcommand, key, value] = args.positionals.slice(3);
 			const exitCode = await preferences(subcommand, key, value, { flags });
 			return process.exit(exitCode);
 		}
@@ -151,7 +154,7 @@ async function runCommand(cmd: string, flags: yargs.Arguments) {
 	switch (cmd) {
 		case 'add': {
 			const { add } = await import('./add/index.js');
-			const packages = flags._.slice(3) as string[];
+			const packages = args.positionals.slice(3);
 			await add(packages, { flags });
 			return;
 		}
@@ -161,7 +164,7 @@ async function runCommand(cmd: string, flags: yargs.Arguments) {
 		case 'link':
 		case 'init': {
 			const { db } = await import('./db/index.js');
-			await db({ flags });
+			await db({ positionals: args.positionals, flags });
 			return;
 		}
 		case 'dev': {
@@ -201,11 +204,21 @@ async function runCommand(cmd: string, flags: yargs.Arguments) {
 }
 
 /** The primary CLI action */
-export async function cli(args: string[]) {
-	const flags = yargs(args, { boolean: ['global'], alias: { g: 'global' } });
-	const cmd = resolveCommand(flags);
+export async function cli(argv: string[]) {
+	const args = parseArgs({
+		args: argv,
+		allowPositionals: true,
+		strict: false,
+		options: {
+			global: { type: 'boolean', short: 'g' },
+			host: { type: 'string' }, // Can be boolean too, which is covered by `strict: false`
+			open: { type: 'string' }, // Can be boolean too, which is covered by `strict: false`
+			// TODO: Add more flags here
+		},
+	});
+	const cmd = resolveCommand(args);
 	try {
-		await runCommand(cmd, flags);
+		await runCommand(cmd, args);
 	} catch (err) {
 		const { throwAndExit } = await import('./throw-and-exit.js');
 		await throwAndExit(cmd, err);
diff --git a/packages/astro/src/cli/info/index.ts b/packages/astro/src/cli/info/index.ts
index cb61e45bfc06..3fa91802f26e 100644
--- a/packages/astro/src/cli/info/index.ts
+++ b/packages/astro/src/cli/info/index.ts
@@ -3,15 +3,14 @@ import { arch, platform } from 'node:os';
 /* eslint-disable no-console */
 import * as colors from 'kleur/colors';
 import prompts from 'prompts';
-import type yargs from 'yargs-parser';
 import type { AstroConfig, AstroUserConfig } from '../../@types/astro.js';
 import { resolveConfig } from '../../core/config/index.js';
 import { ASTRO_VERSION } from '../../core/constants.js';
 import { apply as applyPolyfill } from '../../core/polyfill.js';
-import { flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, flagsToAstroInlineConfig } from '../flags.js';
 
 interface InfoOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 export async function getInfoOutput({
diff --git a/packages/astro/src/cli/preferences/index.ts b/packages/astro/src/cli/preferences/index.ts
index 5735a9b6c26e..3811e7f48708 100644
--- a/packages/astro/src/cli/preferences/index.ts
+++ b/packages/astro/src/cli/preferences/index.ts
@@ -1,5 +1,4 @@
 /* eslint-disable no-console */
-import type yargs from 'yargs-parser';
 import type { AstroSettings } from '../../@types/astro.js';
 
 import { fileURLToPath } from 'node:url';
@@ -15,10 +14,10 @@ import * as msg from '../../core/messages.js';
 import { apply as applyPolyfill } from '../../core/polyfill.js';
 import { DEFAULT_PREFERENCES } from '../../preferences/defaults.js';
 import { type PreferenceKey, coerce, isValidKey } from '../../preferences/index.js';
-import { createLoggerFromFlags, flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, createLoggerFromFlags, flagsToAstroInlineConfig } from '../flags.js';
 
 interface PreferencesOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 const PREFERENCES_SUBCOMMANDS = [
@@ -77,7 +76,7 @@ export async function preferences(
 	const settings = await createSettings(astroConfig, fileURLToPath(astroConfig.root));
 	const opts: SubcommandOptions = {
 		location: flags.global ? 'global' : undefined,
-		json: flags.json,
+		json: !!flags.json,
 	};
 
 	if (subcommand === 'list') {
diff --git a/packages/astro/src/cli/preview/index.ts b/packages/astro/src/cli/preview/index.ts
index 387c1f241a49..468332ce3b97 100644
--- a/packages/astro/src/cli/preview/index.ts
+++ b/packages/astro/src/cli/preview/index.ts
@@ -1,11 +1,10 @@
 import { cyan } from 'kleur/colors';
-import type yargs from 'yargs-parser';
 import { printHelp } from '../../core/messages.js';
 import previewServer from '../../core/preview/index.js';
-import { flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, flagsToAstroInlineConfig } from '../flags.js';
 
 interface PreviewOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 export async function preview({ flags }: PreviewOptions) {
diff --git a/packages/astro/src/cli/sync/index.ts b/packages/astro/src/cli/sync/index.ts
index 6849fee70844..89623e6a800b 100644
--- a/packages/astro/src/cli/sync/index.ts
+++ b/packages/astro/src/cli/sync/index.ts
@@ -1,10 +1,9 @@
-import type yargs from 'yargs-parser';
 import { printHelp } from '../../core/messages.js';
 import _sync from '../../core/sync/index.js';
-import { flagsToAstroInlineConfig } from '../flags.js';
+import { type Flags, flagsToAstroInlineConfig } from '../flags.js';
 
 interface SyncOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 export async function sync({ flags }: SyncOptions) {
diff --git a/packages/astro/src/cli/telemetry/index.ts b/packages/astro/src/cli/telemetry/index.ts
index 277b1cab6721..276f00ef1970 100644
--- a/packages/astro/src/cli/telemetry/index.ts
+++ b/packages/astro/src/cli/telemetry/index.ts
@@ -1,11 +1,10 @@
 /* eslint-disable no-console */
-import type yargs from 'yargs-parser';
 import * as msg from '../../core/messages.js';
 import { telemetry } from '../../events/index.js';
-import { createLoggerFromFlags } from '../flags.js';
+import { type Flags, createLoggerFromFlags } from '../flags.js';
 
 interface TelemetryOptions {
-	flags: yargs.Arguments;
+	flags: Flags;
 }
 
 export async function notify() {
diff --git a/packages/astro/src/core/config/config.ts b/packages/astro/src/core/config/config.ts
index 2e43661a437a..c10066ce3273 100644
--- a/packages/astro/src/core/config/config.ts
+++ b/packages/astro/src/core/config/config.ts
@@ -2,14 +2,12 @@ import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
 import * as colors from 'kleur/colors';
-import type { Arguments as Flags } from 'yargs-parser';
 import { ZodError } from 'zod';
 import type {
 	AstroConfig,
 	AstroInlineConfig,
 	AstroInlineOnlyConfig,
 	AstroUserConfig,
-	CLIFlags,
 } from '../../@types/astro.js';
 import { eventConfigError, telemetry } from '../../events/index.js';
 import { trackAstroConfigZodError } from '../errors/errors.js';
@@ -19,23 +17,6 @@ import { mergeConfig } from './merge.js';
 import { validateConfig } from './validate.js';
 import { loadConfigWithVite } from './vite-load.js';
 
-/** Convert the generic "yargs" flag object into our own, custom TypeScript object. */
-// NOTE: This function will be removed in a later PR. Use `flagsToAstroInlineConfig` instead.
-// All CLI related flow should be located in the `packages/astro/src/cli` directory.
-export function resolveFlags(flags: Partial<Flags>): CLIFlags {
-	return {
-		root: typeof flags.root === 'string' ? flags.root : undefined,
-		site: typeof flags.site === 'string' ? flags.site : undefined,
-		base: typeof flags.base === 'string' ? flags.base : undefined,
-		port: typeof flags.port === 'number' ? flags.port : undefined,
-		config: typeof flags.config === 'string' ? flags.config : undefined,
-		host:
-			typeof flags.host === 'string' || typeof flags.host === 'boolean' ? flags.host : undefined,
-		open:
-			typeof flags.open === 'string' || typeof flags.open === 'boolean' ? flags.open : undefined,
-	};
-}
-
 export function resolveRoot(cwd?: string | URL): string {
 	if (cwd instanceof URL) {
 		cwd = fileURLToPath(cwd);
@@ -66,7 +47,7 @@ async function search(fsMod: typeof fs, root: string) {
 
 interface ResolveConfigPathOptions {
 	root: string;
-	configFile?: string;
+	configFile?: string | false;
 	fs: typeof fs;
 }
 
diff --git a/packages/astro/src/core/config/index.ts b/packages/astro/src/core/config/index.ts
index 3beaa5663523..7ffc290141cc 100644
--- a/packages/astro/src/core/config/index.ts
+++ b/packages/astro/src/core/config/index.ts
@@ -2,7 +2,6 @@ export {
 	configPaths,
 	resolveConfig,
 	resolveConfigPath,
-	resolveFlags,
 	resolveRoot,
 } from './config.js';
 export { createNodeLogger } from './logging.js';
diff --git a/packages/create-astro/src/actions/context.ts b/packages/create-astro/src/actions/context.ts
index 83a13eda7c94..bf1b522bd3bd 100644
--- a/packages/create-astro/src/actions/context.ts
+++ b/packages/create-astro/src/actions/context.ts
@@ -1,7 +1,7 @@
 import os from 'node:os';
+import { parseArgs } from 'node:util';
 import { type Task, prompt } from '@astrojs/cli-kit';
 import { random } from '@astrojs/cli-kit/utils';
-import arg from 'arg';
 
 import getSeasonalData from '../data/seasonal.js';
 import { getName, getVersion } from '../messages.js';
@@ -33,47 +33,44 @@ export interface Context {
 }
 
 export async function getContext(argv: string[]): Promise<Context> {
-	const flags = arg(
-		{
-			'--template': String,
-			'--ref': String,
-			'--yes': Boolean,
-			'--no': Boolean,
-			'--install': Boolean,
-			'--no-install': Boolean,
-			'--git': Boolean,
-			'--no-git': Boolean,
-			'--typescript': String,
-			'--skip-houston': Boolean,
-			'--dry-run': Boolean,
-			'--help': Boolean,
-			'--fancy': Boolean,
-
-			'-y': '--yes',
-			'-n': '--no',
-			'-h': '--help',
+	const args = parseArgs({
+		args: argv,
+		allowPositionals: true,
+		strict: false,
+		options: {
+			template: { type: 'string' },
+			ref: { type: 'string' },
+			yes: { type: 'boolean', short: 'y' },
+			no: { type: 'boolean', short: 'n' },
+			install: { type: 'boolean' },
+			'no-install': { type: 'boolean' },
+			git: { type: 'boolean' },
+			'no-git': { type: 'boolean' },
+			typescript: { type: 'string' },
+			'skip-houston': { type: 'boolean' },
+			'dry-run': { type: 'boolean' },
+			help: { type: 'boolean', short: 'h' },
+			fancy: { type: 'boolean' },
 		},
-		{ argv, permissive: true },
-	);
+	});
 
 	const packageManager = detectPackageManager() ?? 'npm';
-	let cwd = flags['_'][0];
+	const projectName = args.positionals[0];
 	let {
-		'--help': help = false,
-		'--template': template,
-		'--no': no,
-		'--yes': yes,
-		'--install': install,
-		'--no-install': noInstall,
-		'--git': git,
-		'--no-git': noGit,
-		'--typescript': typescript,
-		'--fancy': fancy,
-		'--skip-houston': skipHouston,
-		'--dry-run': dryRun,
-		'--ref': ref,
-	} = flags;
-	let projectName = cwd;
+		help,
+		template,
+		no,
+		yes,
+		install,
+		'no-install': noInstall,
+		git,
+		'no-git': noGit,
+		typescript,
+		fancy,
+		'skip-houston': skipHouston,
+		'dry-run': dryRun,
+		ref,
+	} = args.values;
 
 	if (no) {
 		yes = false;
@@ -82,10 +79,26 @@ export async function getContext(argv: string[]): Promise<Context> {
 		if (typescript == undefined) typescript = 'strict';
 	}
 
+	skipHouston = typeof skipHouston == 'boolean' ? skipHouston : undefined;
 	skipHouston =
 		((os.platform() === 'win32' && !fancy) || skipHouston) ??
 		[yes, no, install, git, typescript].some((v) => v !== undefined);
 
+	// We use `strict: false` in `parseArgs` to allow unknown options, but Node also
+	// simply doesn't guarantee the types anymore, so we need to validate ourselves :(
+	help = !!help;
+	template = typeof template == 'string' ? template : undefined;
+	no = !!no;
+	yes = !!yes;
+	install = !!install;
+	noInstall = !!noInstall;
+	git = !!git;
+	noGit = !!noGit;
+	typescript = typeof typescript == 'string' ? typescript : undefined;
+	fancy = !!fancy;
+	dryRun = !!dryRun;
+	ref = typeof ref == 'string' ? ref : undefined;
+
 	const { messages, hats, ties } = getSeasonalData({ fancy });
 
 	const context: Context = {
@@ -107,7 +120,7 @@ export async function getContext(argv: string[]): Promise<Context> {
 		install: install ?? (noInstall ? false : undefined),
 		git: git ?? (noGit ? false : undefined),
 		typescript,
-		cwd,
+		cwd: projectName,
 		exit(code) {
 			process.exit(code);
 		},
diff --git a/packages/db/package.json b/packages/db/package.json
index 850c6c94775b..6dd5d58238f0 100644
--- a/packages/db/package.json
+++ b/packages/db/package.json
@@ -81,13 +81,11 @@
     "ora": "^8.0.1",
     "prompts": "^2.4.2",
     "strip-ansi": "^7.1.0",
-    "yargs-parser": "^21.1.1",
     "zod": "^3.23.8"
   },
   "devDependencies": {
     "@types/deep-diff": "^1.0.5",
     "@types/prompts": "^2.4.9",
-    "@types/yargs-parser": "^21.0.3",
     "astro": "workspace:*",
     "astro-scripts": "workspace:*",
     "cheerio": "1.0.0",
diff --git a/packages/db/src/core/cli/commands/execute/index.ts b/packages/db/src/core/cli/commands/execute/index.ts
index c6c11cdbb6b9..03b3d00adda2 100644
--- a/packages/db/src/core/cli/commands/execute/index.ts
+++ b/packages/db/src/core/cli/commands/execute/index.ts
@@ -3,7 +3,6 @@ import { getManagedAppTokenOrExit } from '@astrojs/studio';
 import { LibsqlError } from '@libsql/client';
 import type { AstroConfig } from 'astro';
 import { green } from 'kleur/colors';
-import type { Arguments } from 'yargs-parser';
 import {
 	EXEC_DEFAULT_EXPORT_ERROR,
 	EXEC_ERROR,
@@ -16,6 +15,7 @@ import {
 } from '../../../integration/vite-plugin-db.js';
 import { bundleFile, importBundledFile } from '../../../load-file.js';
 import type { DBConfig } from '../../../types.js';
+import type { YargsArguments } from '../../types.js';
 
 export async function cmd({
 	astroConfig,
@@ -24,7 +24,7 @@ export async function cmd({
 }: {
 	astroConfig: AstroConfig;
 	dbConfig: DBConfig;
-	flags: Arguments;
+	flags: YargsArguments;
 }) {
 	const filePath = flags._[4];
 	if (typeof filePath !== 'string') {
diff --git a/packages/db/src/core/cli/commands/login/index.ts b/packages/db/src/core/cli/commands/login/index.ts
index 61f7e0275b15..251d61e05433 100644
--- a/packages/db/src/core/cli/commands/login/index.ts
+++ b/packages/db/src/core/cli/commands/login/index.ts
@@ -7,8 +7,8 @@ import { cyan } from 'kleur/colors';
 import open from 'open';
 import ora from 'ora';
 import prompt from 'prompts';
-import type { Arguments } from 'yargs-parser';
 import type { DBConfig } from '../../../types.js';
+import type { YargsArguments } from '../../types.js';
 
 const isWebContainer =
 	// Stackblitz heuristic
@@ -21,7 +21,7 @@ export async function cmd({
 }: {
 	astroConfig: AstroConfig;
 	dbConfig: DBConfig;
-	flags: Arguments;
+	flags: YargsArguments;
 }) {
 	let session = flags.session;
 
diff --git a/packages/db/src/core/cli/commands/push/index.ts b/packages/db/src/core/cli/commands/push/index.ts
index ecd101ecea79..237f7f6ea29e 100644
--- a/packages/db/src/core/cli/commands/push/index.ts
+++ b/packages/db/src/core/cli/commands/push/index.ts
@@ -1,7 +1,6 @@
 import { getManagedAppTokenOrExit } from '@astrojs/studio';
 import type { AstroConfig } from 'astro';
 import prompts from 'prompts';
-import type { Arguments } from 'yargs-parser';
 import { safeFetch } from '../../../../runtime/utils.js';
 import { MIGRATION_VERSION } from '../../../consts.js';
 import { type DBConfig, type DBSnapshot } from '../../../types.js';
@@ -13,6 +12,7 @@ import {
 	getMigrationQueries,
 	getProductionCurrentSnapshot,
 } from '../../migration-queries.js';
+import type { YargsArguments } from '../../types.js';
 
 export async function cmd({
 	dbConfig,
@@ -20,7 +20,7 @@ export async function cmd({
 }: {
 	astroConfig: AstroConfig;
 	dbConfig: DBConfig;
-	flags: Arguments;
+	flags: YargsArguments;
 }) {
 	const isDryRun = flags.dryRun;
 	const isForceReset = flags.forceReset;
diff --git a/packages/db/src/core/cli/commands/shell/index.ts b/packages/db/src/core/cli/commands/shell/index.ts
index e0a1a6086c4f..5a6bcaa53d1b 100644
--- a/packages/db/src/core/cli/commands/shell/index.ts
+++ b/packages/db/src/core/cli/commands/shell/index.ts
@@ -1,7 +1,6 @@
 import { getManagedAppTokenOrExit } from '@astrojs/studio';
 import type { AstroConfig } from 'astro';
 import { sql } from 'drizzle-orm';
-import type { Arguments } from 'yargs-parser';
 import {
 	createLocalDatabaseClient,
 	createRemoteDatabaseClient,
@@ -11,6 +10,7 @@ import { DB_PATH } from '../../../consts.js';
 import { SHELL_QUERY_MISSING_ERROR } from '../../../errors.js';
 import type { DBConfigInput } from '../../../types.js';
 import { getAstroEnv, getRemoteDatabaseUrl } from '../../../utils.js';
+import type { YargsArguments } from '../../types.js';
 
 export async function cmd({
 	flags,
@@ -18,7 +18,7 @@ export async function cmd({
 }: {
 	dbConfig: DBConfigInput;
 	astroConfig: AstroConfig;
-	flags: Arguments;
+	flags: YargsArguments;
 }) {
 	const query = flags.query;
 	if (!query) {
diff --git a/packages/db/src/core/cli/commands/verify/index.ts b/packages/db/src/core/cli/commands/verify/index.ts
index 950fb661567c..081c8ae3f8ec 100644
--- a/packages/db/src/core/cli/commands/verify/index.ts
+++ b/packages/db/src/core/cli/commands/verify/index.ts
@@ -1,6 +1,5 @@
 import { getManagedAppTokenOrExit } from '@astrojs/studio';
 import type { AstroConfig } from 'astro';
-import type { Arguments } from 'yargs-parser';
 import type { DBConfig } from '../../../types.js';
 import {
 	createCurrentSnapshot,
@@ -9,6 +8,7 @@ import {
 	getMigrationQueries,
 	getProductionCurrentSnapshot,
 } from '../../migration-queries.js';
+import type { YargsArguments } from '../../types.js';
 
 export async function cmd({
 	dbConfig,
@@ -16,7 +16,7 @@ export async function cmd({
 }: {
 	astroConfig: AstroConfig;
 	dbConfig: DBConfig;
-	flags: Arguments;
+	flags: YargsArguments;
 }) {
 	const isJson = flags.json;
 	const appToken = await getManagedAppTokenOrExit(flags.token);
diff --git a/packages/db/src/core/cli/index.ts b/packages/db/src/core/cli/index.ts
index 531b016a6b77..5d9aa10e97dd 100644
--- a/packages/db/src/core/cli/index.ts
+++ b/packages/db/src/core/cli/index.ts
@@ -1,13 +1,13 @@
 import type { AstroConfig } from 'astro';
-import type { Arguments } from 'yargs-parser';
 import { resolveDbConfig } from '../load-file.js';
 import { printHelp } from './print-help.js';
+import type { YargsArguments } from './types.js';
 
 export async function cli({
 	flags,
 	config: astroConfig,
 }: {
-	flags: Arguments;
+	flags: YargsArguments;
 	config: AstroConfig;
 }) {
 	const args = flags._ as string[];
diff --git a/packages/db/src/core/cli/types.ts b/packages/db/src/core/cli/types.ts
new file mode 100644
index 000000000000..9d8aad56b78f
--- /dev/null
+++ b/packages/db/src/core/cli/types.ts
@@ -0,0 +1,7 @@
+// Copy of `yargs-parser` `Arguments` type. We don't use `yargs-parser`
+// in runtime anymore, but our exposed API still relies on this shape.
+export interface YargsArguments {
+	_: Array<string | number>;
+	'--'?: Array<string | number>;
+	[argName: string]: any;
+}
diff --git a/packages/db/src/core/integration/index.ts b/packages/db/src/core/integration/index.ts
index 19c712c802aa..6573c838af13 100644
--- a/packages/db/src/core/integration/index.ts
+++ b/packages/db/src/core/integration/index.ts
@@ -1,4 +1,5 @@
 import { existsSync } from 'fs';
+import { parseArgs } from 'node:util';
 import { dirname } from 'path';
 import { fileURLToPath } from 'url';
 import { type ManagedAppToken, getManagedAppTokenOrExit } from '@astrojs/studio';
@@ -14,7 +15,6 @@ import {
 	loadEnv,
 	mergeConfig,
 } from 'vite';
-import parseArgs from 'yargs-parser';
 import { AstroDbError } from '../../runtime/utils.js';
 import { CONFIG_FILE_NAMES, DB_PATH } from '../consts.js';
 import { EXEC_DEFAULT_EXPORT_ERROR, EXEC_ERROR } from '../errors.js';
@@ -72,8 +72,8 @@ function astroDBIntegration(): AstroIntegration {
 				if (command === 'preview') return;
 
 				let dbPlugin: VitePlugin | undefined = undefined;
-				const args = parseArgs(process.argv.slice(3));
-				connectToStudio = process.env.ASTRO_INTERNAL_TEST_REMOTE || args['remote'];
+				const args = parseArgs({ strict: false });
+				connectToStudio = !!process.env.ASTRO_INTERNAL_TEST_REMOTE || !!args.values.remote;
 
 				if (connectToStudio) {
 					appToken = await getManagedAppTokenOrExit();
diff --git a/packages/upgrade/src/actions/context.ts b/packages/upgrade/src/actions/context.ts
index 2103a53277e2..cd9028e85a54 100644
--- a/packages/upgrade/src/actions/context.ts
+++ b/packages/upgrade/src/actions/context.ts
@@ -1,13 +1,13 @@
 import { pathToFileURL } from 'node:url';
+import { parseArgs } from 'node:util';
 import { prompt } from '@astrojs/cli-kit';
-import arg from 'arg';
 import detectPackageManager from 'preferred-pm';
 
 export interface Context {
 	help: boolean;
 	prompt: typeof prompt;
 	version: string;
-	dryRun?: boolean;
+	dryRun: boolean;
 	cwd: URL;
 	stdin?: typeof process.stdin;
 	stdout?: typeof process.stdout;
@@ -28,22 +28,20 @@ export interface PackageInfo {
 }
 
 export async function getContext(argv: string[]): Promise<Context> {
-	const flags = arg(
-		{
-			'--dry-run': Boolean,
-			'--help': Boolean,
-
-			'-h': '--help',
+	const args = parseArgs({
+		args: argv,
+		allowPositionals: true,
+		strict: false,
+		options: {
+			'dry-run': { type: 'boolean' },
+			help: { type: 'boolean', short: 'h' },
 		},
-		{ argv, permissive: true },
-	);
+	});
 
 	const packageManager = (await detectPackageManager(process.cwd()))?.name ?? 'npm';
-	const {
-		_: [version = 'latest'] = [],
-		'--help': help = false,
-		'--dry-run': dryRun,
-	} = flags;
+	const version = args.positionals[0] ?? 'latest';
+	const help = !!args.values.help;
+	const dryRun = !!args.values['dry-run'];
 
 	return {
 		help,
diff --git a/packages/upgrade/test/context.test.js b/packages/upgrade/test/context.test.js
index bbc887c2ae3c..5ba484740f89 100644
--- a/packages/upgrade/test/context.test.js
+++ b/packages/upgrade/test/context.test.js
@@ -6,12 +6,12 @@ describe('context', () => {
 	it('no arguments', async () => {
 		const ctx = await getContext([]);
 		assert.equal(ctx.version, 'latest');
-		assert.equal(ctx.dryRun, undefined);
+		assert.equal(ctx.dryRun, false);
 	});
 	it('tag', async () => {
 		const ctx = await getContext(['beta']);
 		assert.equal(ctx.version, 'beta');
-		assert.equal(ctx.dryRun, undefined);
+		assert.equal(ctx.dryRun, false);
 	});
 	it('dry run', async () => {
 		const ctx = await getContext(['--dry-run']);
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 6332cd00ff98..923aa7923c0b 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -729,9 +729,6 @@ importers:
       which-pm:
         specifier: ^3.0.0
         version: 3.0.0
-      yargs-parser:
-        specifier: ^21.1.1
-        version: 21.1.1
       zod:
         specifier: ^3.23.8
         version: 3.23.8
@@ -794,9 +791,6 @@ importers:
       '@types/semver':
         specifier: ^7.5.8
         version: 7.5.8
-      '@types/yargs-parser':
-        specifier: ^21.0.3
-        version: 21.0.3
       astro-scripts:
         specifier: workspace:*
         version: link:../../scripts
@@ -1720,15 +1714,9 @@ importers:
 
   packages/astro/performance:
     devDependencies:
-      '@types/yargs-parser':
-        specifier: ^21.0.3
-        version: 21.0.3
       kleur:
         specifier: ^4.1.5
         version: 4.1.5
-      yargs-parser:
-        specifier: ^21.1.1
-        version: 21.1.1
 
   packages/astro/performance/fixtures/md:
     dependencies:
@@ -4252,9 +4240,6 @@ importers:
       strip-ansi:
         specifier: ^7.1.0
         version: 7.1.0
-      yargs-parser:
-        specifier: ^21.1.1
-        version: 21.1.1
       zod:
         specifier: ^3.23.8
         version: 3.23.8
@@ -4265,9 +4250,6 @@ importers:
       '@types/prompts':
         specifier: ^2.4.9
         version: 2.4.9
-      '@types/yargs-parser':
-        specifier: ^21.0.3
-        version: 21.0.3
       astro:
         specifier: workspace:*
         version: link:../astro
@@ -7529,9 +7511,6 @@ packages:
   '@types/xml2js@0.4.14':
     resolution: {integrity: sha512-4YnrRemBShWRO2QjvUin8ESA41rH+9nQGLUGZV/1IDhi3SL9OhdpNC/MrulTWuptXKwhx/aDxE7toV0f/ypIXQ==}
 
-  '@types/yargs-parser@21.0.3':
-    resolution: {integrity: sha512-I4q9QU9MQv4oEOz4tAHJtNz1cwuLxn2F3xcc2iV5WdqLPpUnj30aUuxt1mAxYTG+oe8CZMV/+6rU4S4gRDzqtQ==}
-
   '@typescript-eslint/eslint-plugin@8.0.1':
     resolution: {integrity: sha512-5g3Y7GDFsJAnY4Yhvk8sZtFfV6YNF2caLzjrRPUBzewjPCaj0yokePB4LJSobyCzGMzjZZYFbwuzbfDHlimXbQ==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
@@ -13410,8 +13389,6 @@ snapshots:
     dependencies:
       '@types/node': 18.19.31
 
-  '@types/yargs-parser@21.0.3': {}
-
   '@typescript-eslint/eslint-plugin@8.0.1(@typescript-eslint/parser@8.0.1(eslint@9.9.0(jiti@1.21.0))(typescript@5.5.4))(eslint@9.9.0(jiti@1.21.0))(typescript@5.5.4)':
     dependencies:
       '@eslint-community/regexpp': 4.11.0
diff --git a/scripts/cmd/copy.js b/scripts/cmd/copy.js
index 943c998dfb4f..948ed114fe9b 100644
--- a/scripts/cmd/copy.js
+++ b/scripts/cmd/copy.js
@@ -1,19 +1,20 @@
-import arg from 'arg';
 import { globby as glob } from 'globby';
 import { promises as fs, readFileSync } from 'node:fs';
 import { posix } from 'node:path';
+import { parseArgs } from 'node:util';
 import * as tar from 'tar/create';
 
 const { resolve, dirname, sep, join } = posix;
 
-/** @type {import('arg').Spec} */
-const spec = {
-	'--tgz': Boolean,
-};
-
 export default async function copy() {
-	let { _: patterns, ['--tgz']: isCompress } = arg(spec);
-	patterns = patterns.slice(1);
+	const args = parseArgs({
+		allowPositionals: true,
+		options: {
+			tgz: { type: 'boolean' },
+		},
+	});
+	const patterns = args.positionals.slice(1);
+	const isCompress = args.values.tgz;
 
 	if (isCompress) {
 		const files = await glob(patterns, { gitignore: true });
diff --git a/scripts/cmd/test.js b/scripts/cmd/test.js
index 04f02f73afc0..17f6ecd04101 100644
--- a/scripts/cmd/test.js
+++ b/scripts/cmd/test.js
@@ -3,30 +3,32 @@ import { spec } from 'node:test/reporters';
 import fs from 'node:fs/promises';
 import path from 'node:path';
 import { pathToFileURL } from 'node:url';
-import arg from 'arg';
+import { parseArgs } from 'node:util';
 import glob from 'tiny-glob';
 
 const isCI = !!process.env.CI;
 const defaultTimeout = isCI ? 1400000 : 600000;
 
 export default async function test() {
-	const args = arg({
-		'--match': String, // aka --test-name-pattern: https://nodejs.org/api/test.html#filtering-tests-by-name
-		'--only': Boolean, // aka --test-only: https://nodejs.org/api/test.html#only-tests
-		'--parallel': Boolean, // aka --test-concurrency: https://nodejs.org/api/test.html#test-runner-execution-model
-		'--watch': Boolean, // experimental: https://nodejs.org/api/test.html#watch-mode
-		'--timeout': Number, // Test timeout in milliseconds (default: 30000ms)
-		'--setup': String, // Test setup file
-		// Aliases
-		'-m': '--match',
-		'-o': '--only',
-		'-p': '--parallel',
-		'-w': '--watch',
-		'-t': '--timeout',
-		'-s': '--setup',
+	const args = parseArgs({
+		allowPositionals: true,
+		options: {
+			// aka --test-name-pattern: https://nodejs.org/api/test.html#filtering-tests-by-name
+			match: { type: 'string', alias: 'm' },
+			// aka --test-only: https://nodejs.org/api/test.html#only-tests
+			only: { type: 'boolean', alias: 'o' },
+			// aka --test-concurrency: https://nodejs.org/api/test.html#test-runner-execution-model
+			parallel: { type: 'boolean', alias: 'p' },
+			// experimental: https://nodejs.org/api/test.html#watch-mode
+			watch: { type: 'boolean', alias: 'w' },
+			// Test timeout in milliseconds (default: 30000ms)
+			timeout: { type: 'string', alias: 't' },
+			// Test setup file
+			setup: { type: 'string', alias: 's' },
+		},
 	});
 
-	const pattern = args._[1];
+	const pattern = args.positionals[1];
 	if (!pattern) throw new Error('Missing test glob pattern');
 
 	const files = await glob(pattern, { filesOnly: true, absolute: true });
@@ -34,12 +36,12 @@ export default async function test() {
 	// For some reason, the `only` option does not work and we need to explicitly set the CLI flag instead.
 	// Node.js requires opt-in to run .only tests :(
 	// https://nodejs.org/api/test.html#only-tests
-	if (args['--only']) {
+	if (args.values.only) {
 		process.env.NODE_OPTIONS ??= '';
 		process.env.NODE_OPTIONS += ' --test-only';
 	}
 
-	if (!args['--parallel']) {
+	if (!args.values.parallel) {
 		// If not parallel, we create a temporary file that imports all the test files
 		// so that it all runs in a single process.
 		const tempTestFile = path.resolve('./node_modules/.astro/test.mjs');
@@ -56,12 +58,12 @@ export default async function test() {
 	// https://nodejs.org/api/test.html#runoptions
 	run({
 		files,
-		testNamePatterns: args['--match'],
-		concurrency: args['--parallel'],
-		only: args['--only'],
-		setup: args['--setup'],
-		watch: args['--watch'],
-		timeout: args['--timeout'] ?? defaultTimeout, // Node.js defaults to Infinity, so set better fallback
+		testNamePatterns: args.values.match,
+		concurrency: args.values.parallel,
+		only: args.values.only,
+		setup: args.values.setup,
+		watch: args.values.watch,
+		timeout: args.values.timeout ? Number(args.values.timeout) : defaultTimeout, // Node.js defaults to Infinity, so set better fallback
 	})
 		.on('test:fail', () => {
 			// For some reason, a test fail using the JS API does not set an exit code of 1,