fix: restructure autofixer folders and add tests

src/lib/mcp/autofixers/add-autofixers-issues.test.ts

@@ -0,0 +1,113 @@
+import { describe, expect, it } from 'vitest';
+import { add_autofixers_issues } from './add-autofixers-issues';
+
+describe('add_autofixers_issues', () => {
+	describe('assign_in_effect', () => {
+		it('should add suggestions when assigning to a stateful variable inside an effect', () => {
+			const content = { issues: [], suggestions: [] };
+			const code = `
+			<script>
+				const count = $state(0);
+				$effect(() => {
+					count = 43;
+				});
+			</script>`;
+			add_autofixers_issues(content, code, 5);
+
+			expect(content.suggestions.length).toBeGreaterThanOrEqual(1);
+			expect(content.suggestions).toContain(
+				'The stateful variable "count" is assigned inside an $effect which is generally consider a malpractice. Consider using $derived if possible.',
+			);
+		});
+
+		it('should add a suggestion for each variable assigned within an effect', () => {
+			const content = { issues: [], suggestions: [] };
+			const code = `
+			<script>
+				const count = $state(0);
+				const count2 = $state(0);
+				$effect(() => {
+					count = 43;
+					count2 = 44;
+				});
+			</script>`;
+			add_autofixers_issues(content, code, 5);
+
+			expect(content.suggestions.length).toBeGreaterThanOrEqual(2);
+			expect(content.suggestions).toContain(
+				'The stateful variable "count" is assigned inside an $effect which is generally consider a malpractice. Consider using $derived if possible.',
+			);
+			expect(content.suggestions).toContain(
+				'The stateful variable "count2" is assigned inside an $effect which is generally consider a malpractice. Consider using $derived if possible.',
+			);
+		});
+		it('should not add a suggestion for variables that are not assigned within an effect', () => {
+			const content = { issues: [], suggestions: [] };
+			const code = `
+			<script>
+				const count = $state(0);
+			</script>
+			
+			<button onclick={() => count = 43}>Increment</button>
+			`;
+			add_autofixers_issues(content, code, 5);
+
+			expect(content.suggestions).not.toContain(
+				'The stateful variable "count" is assigned inside an $effect which is generally consider a malpractice. Consider using $derived if possible.',
+			);
+		});
+
+		it("should not add a suggestions for variables that are assigned within an effect but aren't stateful", () => {
+			const content = { issues: [], suggestions: [] };
+			const code = `
+			<script>
+				const count = 0;
+				
+				$effect(() => {
+					count = 43;
+				});
+			</script>`;
+			add_autofixers_issues(content, code, 5);
+
+			expect(content.suggestions).not.toContain(
+				'The stateful variable "count" is assigned inside an $effect which is generally consider a malpractice. Consider using $derived if possible.',
+			);
+		});
+
+		it('should add a suggestion for variables that are assigned within an effect with an update', () => {
+			const content = { issues: [], suggestions: [] };
+			const code = `
+			<script>
+				let count = $state(0);
+				
+				$effect(() => {
+					count++;
+				});
+			</script>
+			`;
+			add_autofixers_issues(content, code, 5);
+
+			expect(content.suggestions).toContain(
+				'The stateful variable "count" is assigned inside an $effect which is generally consider a malpractice. Consider using $derived if possible.',
+			);
+		});
+
+		it('should add a suggestion for variables that are mutated within an effect', () => {
+			const content = { issues: [], suggestions: [] };
+			const code = `
+			<script>
+				let count = $state({ value: 0 });
+				
+				$effect(() => {
+					count.value = 42;
+				});
+			</script>
+			`;
+			add_autofixers_issues(content, code, 5);
+
+			expect(content.suggestions).toContain(
+				'The stateful variable "count" is assigned inside an $effect which is generally consider a malpractice. Consider using $derived if possible.',
+			);
+		});
+	});
+});

src/lib/mcp/autofixers/add-autofixers-issues.ts

@@ -0,0 +1,22 @@
+import { parse } from '../../parse/parse.js';
+import { walk } from '../../index.js';
+import type { Node } from 'estree';
+import * as autofixers from './visitors/index.js';
+
+export function add_autofixers_issues(
+	content: { issues: string[]; suggestions: string[] },
+	code: string,
+	desired_svelte_version: number,
+	filename = 'Component.svelte',
+) {
+	const parsed = parse(code, filename);
+
+	// Run each autofixer separately to avoid interrupting logic flow
+	for (const autofixer of Object.values(autofixers)) {
+		walk(
+			parsed.ast as unknown as Node,
+			{ output: content, parsed, desired_svelte_version },
+			autofixer,
+		);
+	}
+}

src/lib/mcp/autofixers/add-compile-issues.ts

@@ -0,0 +1,20 @@
+import { compile } from 'svelte/compiler';
+
+export function add_compile_issues(
+	content: { issues: string[]; suggestions: string[] },
+	code: string,
+	desired_svelte_version: number,
+	filename = 'Component.svelte',
+) {
+	const compilation_result = compile(code, {
+		filename: filename || 'Component.svelte',
+		generate: false,
+		runes: desired_svelte_version >= 5,
+	});
+
+	for (const warning of compilation_result.warnings) {
+		content.issues.push(
+			`${warning.message} at line ${warning.start?.line}, column ${warning.start?.column}`,
+		);
+	}
+}

src/lib/mcp/eslint.ts → src/lib/mcp/autofixers/add-eslint-issues.ts

@@ -48,7 +48,7 @@ function base_config(svelte_config: Config): ESLint.Options['baseConfig'] {
 	];
 }
 
-export function get_linter(version: number) {
+function get_linter(version: number) {
 	if (version < 5) {
 		return (svelte_4_linter ??= new ESLint({
 			overrideConfigFile: true,
@@ -68,3 +68,23 @@ export function get_linter(version: number) {
 		}),
 	}));
 }
+
+export async function add_eslint_issues(
+	content: { issues: string[]; suggestions: string[] },
+	code: string,
+	desired_svelte_version: number,
+	filename = 'Component.svelte',
+) {
+	const eslint = get_linter(desired_svelte_version);
+	const results = await eslint.lintText(code, { filePath: filename || './Component.svelte' });
+
+	for (const message of results[0].messages) {
+		if (message.severity === 2) {
+			content.issues.push(`${message.message} at line ${message.line}, column ${message.column}`);
+		} else if (message.severity === 1) {
+			content.suggestions.push(
+				`${message.message} at line ${message.line}, column ${message.column}`,
+			);
+		}
+	}
+}

src/lib/mcp/autofixers/ast/utils.ts

@@ -0,0 +1,16 @@
+import type { Identifier, MemberExpression } from 'estree';
+
+/**
+ * Gets the left-most identifier of a member expression or identifier.
+ */
+export function left_most_id(expression: MemberExpression | Identifier) {
+	while (expression.type === 'MemberExpression') {
+		expression = expression.object as MemberExpression | Identifier;
+	}
+
+	if (expression.type !== 'Identifier') {
+		return null;
+	}
+
+	return expression;
+}

src/lib/mcp/autofixers/visitors/assign-in-effect.ts

@@ -0,0 +1,62 @@
+import type { AssignmentExpression, Identifier, Node, UpdateExpression } from 'estree';
+import type { Autofixer, AutofixerState } from '.';
+import { left_most_id } from '../ast/utils';
+import type { SvelteNode } from 'svelte-eslint-parser/lib/ast';
+import type { Context } from 'zimmerframe';
+
+function run_if_in_effect(path: (Node | SvelteNode)[], state: AutofixerState, to_run: () => void) {
+	const in_effect = path.findLast(
+		(node) =>
+			node.type === 'CallExpression' &&
+			node.callee.type === 'Identifier' &&
+			node.callee.name === '$effect',
+	);
+
+	if (
+		in_effect &&
+		in_effect.type === 'CallExpression' &&
+		(in_effect.callee.type === 'Identifier' || in_effect.callee.type === 'MemberExpression')
+	) {
+		if (state.parsed.is_rune(in_effect, ['$effect', '$effect.pre'])) {
+			to_run();
+		}
+	}
+}
+
+function visitor(
+	node: UpdateExpression | AssignmentExpression,
+	{ state, path }: Context<Node | SvelteNode, AutofixerState>,
+) {
+	run_if_in_effect(path, state, () => {
+		function check_if_stateful_id(id: Identifier) {
+			const reference = state.parsed.find_reference_by_id(id);
+			const definition = reference?.resolved?.defs[0];
+			if (definition && definition.type === 'Variable') {
+				const init = definition.node.init;
+				if (
+					init?.type === 'CallExpression' &&
+					state.parsed.is_rune(init, ['$state', '$state.raw'])
+				) {
+					state.output.suggestions.push(
+						`The stateful variable "${id.name}" is assigned inside an $effect which is generally consider a malpractice. Consider using $derived if possible.`,
+					);
+				}
+			}
+		}
+		const variable = node.type === 'UpdateExpression' ? node.argument : node.left;
+
+		if (variable.type === 'Identifier') {
+			check_if_stateful_id(variable);
+		} else if (variable.type === 'MemberExpression') {
+			const object = left_most_id(variable);
+			if (object) {
+				check_if_stateful_id(object);
+			}
+		}
+	});
+}
+
+export const assign_in_effect: Autofixer = {
+	UpdateExpression: visitor,
+	AssignmentExpression: visitor,
+};

src/lib/mcp/autofixers/visitors/index.ts

@@ -0,0 +1,14 @@
+import type { Node } from 'estree';
+import type { AST } from 'svelte-eslint-parser';
+import type { Visitors } from 'zimmerframe';
+import type { ParseResult } from '../../../parse/parse.js';
+
+export type AutofixerState = {
+	output: { issues: string[]; suggestions: string[] };
+	parsed: ParseResult;
+	desired_svelte_version: number;
+};
+
+export type Autofixer = Visitors<Node | AST.SvelteNode, AutofixerState>;
+
+export * from './assign-in-effect.js';