routie dev init since i didn't adhere to any proper guidance up until now

frontend/node_modules/eslint-plugin-unicorn/rules/prefer-array-flat-map.js

@@ -0,0 +1,86 @@
+import {isNodeMatches} from './utils/is-node-matches.js';
+import {isMethodCall} from './ast/index.js';
+import {removeMethodCall} from './fix/index.js';
+
+const MESSAGE_ID = 'prefer-array-flat-map';
+const messages = {
+	[MESSAGE_ID]: 'Prefer `.flatMap(…)` over `.map(…).flat()`.',
+};
+
+const ignored = ['React.Children', 'Children'];
+
+/** @param {import('eslint').Rule.RuleContext} context */
+const create = context => {
+	context.on('CallExpression', callExpression => {
+		if (!(
+			isMethodCall(callExpression, {
+				method: 'flat',
+				optionalCall: false,
+				optionalMember: false,
+			})
+			&& (
+				callExpression.arguments.length === 0
+				|| (
+					callExpression.arguments.length === 1
+					&& callExpression.arguments[0].type === 'Literal'
+					&& callExpression.arguments[0].raw === '1'
+				)
+			)
+			&& isMethodCall(callExpression.callee.object, {
+				method: 'map',
+				optionalCall: false,
+			})
+		)) {
+			return;
+		}
+
+		const flatCallExpression = callExpression;
+		const mapCallExpression = flatCallExpression.callee.object;
+		if (isNodeMatches(mapCallExpression.callee.object, ignored)) {
+			return;
+		}
+
+		const {sourceCode} = context;
+		const mapProperty = mapCallExpression.callee.property;
+
+		return {
+			node: flatCallExpression,
+			loc: {
+				start: sourceCode.getLoc(mapProperty).start,
+				end: sourceCode.getLoc(flatCallExpression).end,
+			},
+			messageId: MESSAGE_ID,
+			* fix(fixer) {
+				// Removes:
+				//   map(…).flat();
+				//         ^^^^^^^
+				//   (map(…)).flat();
+				//           ^^^^^^^
+				yield removeMethodCall(fixer, flatCallExpression, context);
+
+				// Renames:
+				//   map(…).flat();
+				//   ^^^
+				//   (map(…)).flat();
+				//    ^^^
+				yield fixer.replaceText(mapProperty, 'flatMap');
+			},
+		};
+	});
+};
+
+/** @type {import('eslint').Rule.RuleModule} */
+const config = {
+	create,
+	meta: {
+		type: 'suggestion',
+		docs: {
+			description: 'Prefer `.flatMap(…)` over `.map(…).flat()`.',
+			recommended: 'unopinionated',
+		},
+		fixable: 'code',
+		messages,
+	},
+};
+
+export default config;