docs: add link to CLAUDE.md and AGENTS.md docs

.changeset/good-trams-kneel.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/mcp': patch
+---
+
+feat: add autofixer to tell the LLM to check if some function called in effect is assigning state #26

.changeset/tough-donkeys-attend.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/mcp': patch
+---
+
+feat: add bind:this -> attachment and action -> attachment autofixer #20

.github/workflows/check.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
         with:
-          version: 10.18.0
+          version: 10.18.1
 
       - name: Setup Node.js
         uses: actions/setup-node@v5

.github/workflows/lint.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
         with:
-          version: 10.18.0
+          version: 10.18.1
 
       - name: Setup Node.js
         uses: actions/setup-node@v5

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
         with:
-          version: 10.18.0
+          version: 10.18.1
 
       - name: Setup Node.js
         uses: actions/setup-node@v5

documentation/docs/10-introduction/10-overview.md

@@ -13,7 +13,7 @@ The setup varies based on the version of the MCP you prefer — remote or local
 
 ## Usage
 
-To get the most out of the MCP server we recommend including the following prompt in your `AGENTS.md` (or `CLAUDE.md`, if using Claude Code). This will tell the LLM which tools are available and when it's appropriate to use them.
+To get the most out of the MCP server we recommend including the following prompt in your [`AGENTS.md`](https://agents.md) (or [`CLAUDE.md`](https://docs.claude.com/en/docs/claude-code/memory#claude-md-imports), if using Claude Code). This will tell the LLM which tools are available and when it's appropriate to use them.
 
 ```md
 You are able to use the Svelte MCP server, where you have access to comprehensive Svelte 5 and SvelteKit documentation. Here's how to use the available tools effectively:

documentation/docs/20-setup/20-local-setup.md

@@ -108,6 +108,25 @@ It will open a file with your MCP servers where you can add the following config
 }
 ```
 
+## Zed
+
+- Open the command palette
+- Search and select "agent:open settings"
+- In settings panel look for `Model Context Protocol (MCP) Servers`
+- Click on "Add Server"
+- Select: "Add Custom Server"
+
+It will open a popup with MCP server config where you can add the following configuration:
+
+```json
+{
+	"svelte": {
+		"command": "npx",
+		"args": ["-y", "@sveltejs/mcp"]
+	}
+}
+```
+
 ## Other clients
 
 If we didn't include the MCP client you are using, refer to their documentation for `stdio` servers and use `npx` as the command and `-y @sveltejs/mcp` as the arguments.

package.json

@@ -3,7 +3,7 @@
 	"version": "0.0.1",
 	"description": "The official Svelte MCP server implementation",
 	"type": "module",
-	"packageManager": "pnpm@10.18.0",
+	"packageManager": "pnpm@10.18.1",
 	"scripts": {
 		"build": "pnpm -r run build",
 		"dev": "pnpm --filter @sveltejs/mcp-remote run dev",

packages/mcp-server/src/mcp/autofixers/add-autofixers-issues.test.ts

@@ -133,6 +133,36 @@ describe('add_autofixers_issues', () => {
 				);
 			});
 		});
+
+		it('should add a suggestion when calling a function inside an effect', () => {
+			const content = run_autofixers_on_code(`
+			<script>
+				import { fetch_data } from './data.js';
+				$effect(() => {
+					fetch_data();
+				});
+			</script>`);
+
+			expect(content.suggestions.length).toBeGreaterThanOrEqual(1);
+			expect(content.suggestions).toContain(
+				`You are calling the function \`fetch_data\` inside an $effect. Please check if the function is reassigning a stateful variable because that's considered malpractice and check if it could use  \`$derived\` instead. Ignore this suggestion if you are sure this function is not assigning any stateful variable or if you can't check if it does.`,
+			);
+		});
+
+		it('should add a suggestion when calling a function inside an effect (with non identifier callee)', () => {
+			const content = run_autofixers_on_code(`
+			<script>
+				import { fetch_data } from './data.js';
+				$effect(() => {
+					fetch_data.fetch();
+				});
+			</script>`);
+
+			expect(content.suggestions.length).toBeGreaterThanOrEqual(1);
+			expect(content.suggestions).toContain(
+				`You are calling a function inside an $effect. Please check if the function is reassigning a stateful variable because that's considered malpractice and check if it could use  \`$derived\` instead. Ignore this suggestion if you are sure this function is not assigning any stateful variable or if you can't check if it does.`,
+			);
+		});
 	});
 
 	with_possible_inits('($init)', ({ init }) => {
@@ -484,4 +514,177 @@ describe('add_autofixers_issues', () => {
 			);
 		});
 	});
+
+	describe('suggest_attachments', () => {
+		describe('bind:this', () => {
+			it('should add suggestions when using bind:this on an element', () => {
+				const content = run_autofixers_on_code(`
+			<script>
+				let a = $state();	
+			</script>
+
+			<a bind:this={a} />`);
+
+				expect(content.suggestions.length).toBeGreaterThanOrEqual(1);
+				expect(content.suggestions).toContain(
+					'The usage of `bind:this` can often be replaced with an easier to read `action` or even better an `attachment`. Consider using the latter if possible.',
+				);
+			});
+
+			it('should not add suggestions when using bind:this on a component', () => {
+				const content = run_autofixers_on_code(`
+			<script>
+				import Child from './Child.svelte';
+				let a = $state();	
+			</script>
+
+			<Child bind:this={a} />`);
+
+				expect(content.suggestions).not.toContain(
+					'The usage of `bind:this` can often be replaced with an easier to read `action` or even better an `attachment`. Consider using the latter if possible.',
+				);
+			});
+
+			it('should not add suggestions when using bind:this on a component nested in an element', () => {
+				const content = run_autofixers_on_code(`
+			<script>
+				import Child from './Child.svelte';
+				let a = $state();	
+			</script>
+
+			<div>
+				<Child bind:this={a} />
+			</div>`);
+
+				expect(content.suggestions).not.toContain(
+					'The usage of `bind:this` can often be replaced with an easier to read `action` or even better an `attachment`. Consider using the latter if possible.',
+				);
+			});
+
+			it('should add suggestions but not suggest attachments when using bind:this on an element and the desired svelte version is 4', () => {
+				const content = run_autofixers_on_code(
+					`
+			<script>
+				let a;	
+			</script>
+
+			<a bind:this={a} />`,
+					4,
+				);
+
+				expect(content.suggestions.length).toBeGreaterThanOrEqual(1);
+				expect(content.suggestions).toContain(
+					'The usage of `bind:this` can often be replaced with an easier to read `action`. Consider using the latter if possible.',
+				);
+			});
+		});
+
+		describe('use:', () => {
+			it('should add suggestions when using use: on an element and the action is declared as a function', () => {
+				const content = run_autofixers_on_code(
+					`<script>
+						function my_action(node) {
+							// do something with the node
+						}
+					</script>
+
+					<a use:my_action />`,
+				);
+
+				expect(content.suggestions.length).toBeGreaterThanOrEqual(1);
+				expect(content.suggestions).toContain(
+					'Consider using an `attachment` instead of an `action` for "my_action".',
+				);
+			});
+
+			it('should add suggestions when using use: on an element and the action is declared as a variable', () => {
+				const content = run_autofixers_on_code(
+					`<script>
+						const my_action = (node) => {
+							// do something with the node
+						}
+					</script>
+
+					<a use:my_action />`,
+				);
+
+				expect(content.suggestions.length).toBeGreaterThanOrEqual(1);
+				expect(content.suggestions).toContain(
+					'Consider using an `attachment` instead of an `action` for "my_action".',
+				);
+			});
+
+			it('should add suggestions when using use: on an element and the action is declared as an object', () => {
+				const content = run_autofixers_on_code(
+					`<script>
+						const my_action = {
+							action: (node) => {
+								// do something with the node
+							}
+						};
+					</script>
+
+					<a use:my_action.action />`,
+				);
+
+				expect(content.suggestions.length).toBeGreaterThanOrEqual(1);
+				expect(content.suggestions).toContain(
+					'Consider using an `attachment` instead of an `action` for "my_action".',
+				);
+			});
+
+			it('should not add suggestions when using use: on an element and the desired svelte version is 4', () => {
+				const content = run_autofixers_on_code(
+					`<script>
+						function my_action(node) {
+							// do something with the node
+						}
+					</script>
+
+					<a use:my_action />`,
+					4,
+				);
+
+				expect(content.suggestions).not.toContain(
+					'Consider using an `attachment` instead of an `action` for "my_action".',
+				);
+			});
+
+			it('should not add suggestions when using use: on an element and the action comes from an import', () => {
+				const content = run_autofixers_on_code(
+					`<script>
+						import { my_action } from './actions.js';
+					</script>
+
+					<a use:my_action />`,
+				);
+
+				expect(content.suggestions).not.toContain(
+					'Consider using an `attachment` instead of an `action` for "my_action".',
+				);
+			});
+
+			it('should not add suggestions when using use: on an element and the action comes from the props', () => {
+				const content = run_autofixers_on_code(
+					`<script>
+						const { my_action } = $props();
+					</script>
+
+					<a use:my_action />`,
+				);
+
+				expect(content.suggestions).not.toContain(
+					'Consider using an `attachment` instead of an `action` for "my_action".',
+				);
+			});
+
+			it('should not add suggestions when using use: on an element and the action comes from a global variable', () => {
+				const content = run_autofixers_on_code(`<a use:my_action />`);
+
+				expect(content.suggestions).not.toContain(
+					'Consider using an `attachment` instead of an `action` for "my_action".',
+				);
+			});
+		});
+	});
 });

packages/mcp-server/src/mcp/autofixers/visitors/assign-in-effect.ts

@@ -1,4 +1,10 @@
-import type { AssignmentExpression, Identifier, Node, UpdateExpression } from 'estree';
+import type {
+	AssignmentExpression,
+	CallExpression,
+	Identifier,
+	Node,
+	UpdateExpression,
+} from 'estree';
 import type { Autofixer, AutofixerState } from './index.js';
 import { left_most_id } from '../ast/utils.js';
 import type { AST } from 'svelte-eslint-parser';
@@ -19,9 +25,9 @@ function run_if_in_effect(
 	}
 }
 
-function visitor(
+function assign_or_update_visitor(
 	node: UpdateExpression | AssignmentExpression,
-	{ state, path }: Context<Node | AST.SvelteNode, AutofixerState>,
+	{ state, path, next }: Context<Node | AST.SvelteNode, AutofixerState>,
 ) {
 	run_if_in_effect(path, state, () => {
 		function check_if_stateful_id(id: Identifier) {
@@ -50,9 +56,25 @@ function visitor(
 			}
 		}
 	});
+	next();
+}
+
+function call_expression_visitor(
+	node: CallExpression,
+	{ state, path, next }: Context<Node | AST.SvelteNode, AutofixerState>,
+) {
+	run_if_in_effect(path, state, () => {
+		const function_name =
+			node.callee.type === 'Identifier' ? `the function \`${node.callee.name}\`` : 'a function';
+		state.output.suggestions.push(
+			`You are calling ${function_name} inside an $effect. Please check if the function is reassigning a stateful variable because that's considered malpractice and check if it could use  \`$derived\` instead. Ignore this suggestion if you are sure this function is not assigning any stateful variable or if you can't check if it does.`,
+		);
+	});
+	next();
 }
 
 export const assign_in_effect: Autofixer = {
-	UpdateExpression: visitor,
-	AssignmentExpression: visitor,
+	UpdateExpression: assign_or_update_visitor,
+	AssignmentExpression: assign_or_update_visitor,
+	CallExpression: call_expression_visitor,
 };

packages/mcp-server/src/mcp/autofixers/visitors/index.ts

@@ -16,3 +16,4 @@ export * from './wrong-property-access-state.js';
 export * from './imported-runes.js';
 export * from './derived-with-function.js';
 export * from './use-runes-instead-of-store.js';
+export * from './suggest-attachments.js';

packages/mcp-server/src/mcp/autofixers/visitors/suggest-attachments.ts

@@ -0,0 +1,47 @@
+import type { Identifier } from 'estree';
+import type { Autofixer } from './index.js';
+import { left_most_id } from '../ast/utils.js';
+
+export const suggest_attachments: Autofixer = {
+	SvelteDirective(node, { state, next, path }) {
+		if (node.kind === 'Binding' && node.key.name.name === 'this') {
+			const parent_element = path.findLast((p) => p.type === 'SvelteElement');
+			if (parent_element?.kind === 'html' && parent_element.startTag.attributes.includes(node)) {
+				let better_an_attachment = ` or even better an \`attachment\``;
+				if (state.desired_svelte_version === 4) {
+					better_an_attachment = ``;
+				}
+				state.output.suggestions.push(
+					`The usage of \`bind:this\` can often be replaced with an easier to read \`action\`${better_an_attachment}. Consider using the latter if possible.`,
+				);
+			}
+		} else if (node.kind === 'Action' && state.desired_svelte_version === 5) {
+			let id: Identifier | null = null;
+			if (node.key.name.type === 'Identifier') {
+				id = node.key.name;
+			} else if (node.key.name.type === 'MemberExpression') {
+				id = left_most_id(node.key.name);
+			}
+			if (id) {
+				const reference = state.parsed.find_reference_by_id(id);
+				const definition = reference?.resolved?.defs[0];
+				console.log(definition);
+				if (
+					definition &&
+					(definition.type === 'Variable' ||
+						!(definition.type === 'ImportBinding' || definition.type === 'Parameter')) &&
+					!(
+						definition.type === 'Variable' &&
+						definition.node.init?.type === 'CallExpression' &&
+						state.parsed.is_rune(definition.node.init, ['$props'])
+					)
+				) {
+					state.output.suggestions.push(
+						`Consider using an \`attachment\` instead of an \`action\` for "${id.name}".`,
+					);
+				}
+			}
+		}
+		next();
+	},
+};