From 8ff9839b881bf98c7fb99b5ef2dc9ace3e9618c4 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 00:10:11 +0800
Subject: [PATCH 01/19] update eslint docs

---
 documentation/docs/30-add-ons/10-eslint.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/documentation/docs/30-add-ons/10-eslint.md b/documentation/docs/30-add-ons/10-eslint.md
index d12aed33f..70438105d 100644
--- a/documentation/docs/30-add-ons/10-eslint.md
+++ b/documentation/docs/30-add-ons/10-eslint.md
@@ -14,5 +14,5 @@ npx sv add eslint
 
 - the relevant packages installed including `eslint-plugin-svelte`
 - an `eslint.config.js` file
-- updated `.vscode/settings.json`
+- updated `.vscode/extensions.json`
 - configured to work with TypeScript and `prettier` if you're using those packages

From f0f2bbd24b3944b5b0d984d9beca2ea6274ef16a Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 00:10:30 +0800
Subject: [PATCH 02/19] add a placeholder for rules

---
 packages/sv/src/addons/eslint.ts | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/packages/sv/src/addons/eslint.ts b/packages/sv/src/addons/eslint.ts
index ec48acfcb..a26497eda 100644
--- a/packages/sv/src/addons/eslint.ts
+++ b/packages/sv/src/addons/eslint.ts
@@ -109,6 +109,23 @@ export default defineAddon({
 				eslintConfigs.push(svelteTSParserConfig);
 			}
 
+			const rulesOverride = js.object.create({
+				rules: {}
+			});
+			eslintConfigs.push(rulesOverride);
+
+			if (rulesOverride.properties[0].type !== 'Property') {
+				throw new Error('rulesOverride.properties[0].type !== "Property"');
+			}
+			comments.add(rulesOverride.properties[0].key, {
+				type: 'Line',
+				value: ' Override or add rule settings here, such as:'
+			});
+			comments.add(rulesOverride.properties[0].key, {
+				type: 'Line',
+				value: " 'svelte/rule-name': 'error'"
+			});
+
 			const exportExpression = js.functions.createCall({ name: 'defineConfig', args: [] });
 			if (typescript) {
 				exportExpression.arguments.push(...eslintConfigs);

From 320c44bab597046cc81f33f5489a8a82af502b7d Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 00:10:50 +0800
Subject: [PATCH 03/19] improve eslint scanning

---
 packages/sv/src/addons/common.ts | 80 +++++++++++++++++++++++++-------
 1 file changed, 62 insertions(+), 18 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index 23605fe11..f7e581f7f 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -19,8 +19,8 @@ export function addEslintConfigPrettier(content: string): string {
 			svelteImportName = specifier.local.name as string;
 		}
 	}
-
 	svelteImportName ??= 'svelte';
+
 	js.imports.addDefault(ast, { from: 'eslint-plugin-svelte', as: svelteImportName });
 	js.imports.addDefault(ast, { from: 'eslint-config-prettier', as: 'prettier' });
 
@@ -38,24 +38,68 @@ export function addEslintConfigPrettier(content: string): string {
 	if (!js.common.contains(eslintConfig, sveltePrettierConfig))
 		nodesToInsert.push(sveltePrettierConfig);
 
-	const elements =
-		eslintConfig.type === 'ArrayExpression' ? eslintConfig.elements : eslintConfig.arguments;
-	// finds index of `svelte.configs["..."]`
-	const idx = elements.findIndex(
-		(el) =>
-			el?.type === 'MemberExpression' &&
-			el.object.type === 'MemberExpression' &&
-			el.object.property.type === 'Identifier' &&
-			el.object.property.name === 'configs' &&
-			el.object.object.type === 'Identifier' &&
-			el.object.object.name === svelteImportName
-	);
+	if (eslintConfig.type === 'CallExpression') {
+		// export default defineConfig(...)
+		if (
+			eslintConfig.arguments.length === 1 &&
+			eslintConfig.arguments[0].type === 'ArrayExpression'
+		) {
+			// javascript defineConfig([...])
+			const idx = eslintConfig.arguments[0].elements.findIndex(
+				(el) =>
+					el?.type === 'MemberExpression' &&
+					el.object.type === 'MemberExpression' &&
+					el.object.property.type === 'Identifier' &&
+					el.object.property.name === 'configs' &&
+					el.object.object.type === 'Identifier' &&
+					el.object.object.name === svelteImportName
+			);
+			if (idx !== -1) {
+				eslintConfig.arguments[0].elements.splice(idx + 1, 0, ...nodesToInsert);
+			} else {
+				// append to the end as a fallback
+				eslintConfig.arguments[0].elements.push(...nodesToInsert);
+			}
+		} else {
+			//typescript defineConfig(...)
+			const idx = eslintConfig.arguments.findIndex(
+				(el) =>
+					el?.type === 'MemberExpression' &&
+					el.object.type === 'MemberExpression' &&
+					el.object.property.type === 'Identifier' &&
+					el.object.property.name === 'configs' &&
+					el.object.object.type === 'Identifier' &&
+					el.object.object.name === svelteImportName
+			);
+			if (idx !== -1) {
+				eslintConfig.arguments.splice(idx + 1, 0, ...nodesToInsert);
+			} else {
+				// append to the end as a fallback
+				eslintConfig.arguments.push(...nodesToInsert);
+			}
+		}
+	}
 
-	if (idx !== -1) {
-		elements.splice(idx + 1, 0, ...nodesToInsert);
-	} else {
-		// append to the end as a fallback
-		elements.push(...nodesToInsert);
+	// export default []
+	if (eslintConfig.type === 'ArrayExpression') {
+		// find index of `...svelte.configs["..."]`
+		const idx = eslintConfig.elements.findIndex(
+			(el) =>
+				el?.type === 'SpreadElement' &&
+				el.argument.type === 'MemberExpression' &&
+				el.argument.object.type === 'MemberExpression' &&
+				el.argument.object.property.type === 'Identifier' &&
+				el.argument.object.property.name === 'configs' &&
+				el.argument.object.object.type === 'Identifier' &&
+				el.argument.object.object.name === svelteImportName
+		);
+
+		if (idx !== -1) {
+			eslintConfig.elements.splice(idx + 1, 0, ...nodesToInsert);
+		} else {
+			// append to the end as a fallback
+			eslintConfig.elements.push(...nodesToInsert);
+		}
 	}
 
 	return generateCode();

From a0f007a684f8dd0703241831b684ddc6ec6ec202 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 00:34:38 +0800
Subject: [PATCH 04/19] named predicates

---
 packages/sv/src/addons/common.ts | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index f7e581f7f..55b9e48ad 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -27,8 +27,11 @@ export function addEslintConfigPrettier(content: string): string {
 	const fallbackConfig = js.common.parseExpression('[]');
 	const defaultExport = js.exports.createDefault(ast, { fallback: fallbackConfig });
 	const eslintConfig = defaultExport.value;
-	if (eslintConfig.type !== 'ArrayExpression' && eslintConfig.type !== 'CallExpression')
-		return content;
+
+	const isDefineConfig = eslintConfig.type === 'CallExpression'; // export default defineConfig()
+	const isArrayExport = eslintConfig.type === 'ArrayExpression'; // export default []
+
+	if (!isArrayExport && !isDefineConfig) return content;
 
 	const prettier = js.common.parseExpression('prettier');
 	const sveltePrettierConfig = js.common.parseExpression(`${svelteImportName}.configs.prettier`);
@@ -38,13 +41,12 @@ export function addEslintConfigPrettier(content: string): string {
 	if (!js.common.contains(eslintConfig, sveltePrettierConfig))
 		nodesToInsert.push(sveltePrettierConfig);
 
-	if (eslintConfig.type === 'CallExpression') {
-		// export default defineConfig(...)
+	if (isDefineConfig) {
 		if (
 			eslintConfig.arguments.length === 1 &&
 			eslintConfig.arguments[0].type === 'ArrayExpression'
 		) {
-			// javascript defineConfig([...])
+			// javascript - defineConfig([...])
 			const idx = eslintConfig.arguments[0].elements.findIndex(
 				(el) =>
 					el?.type === 'MemberExpression' &&
@@ -61,7 +63,7 @@ export function addEslintConfigPrettier(content: string): string {
 				eslintConfig.arguments[0].elements.push(...nodesToInsert);
 			}
 		} else {
-			//typescript defineConfig(...)
+			//typescript - defineConfig(...)
 			const idx = eslintConfig.arguments.findIndex(
 				(el) =>
 					el?.type === 'MemberExpression' &&
@@ -80,8 +82,7 @@ export function addEslintConfigPrettier(content: string): string {
 		}
 	}
 
-	// export default []
-	if (eslintConfig.type === 'ArrayExpression') {
+	if (isArrayExport) {
 		// find index of `...svelte.configs["..."]`
 		const idx = eslintConfig.elements.findIndex(
 			(el) =>

From 6b3f5f2582ccf3815052e91fa54db1535e73083d Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 00:34:48 +0800
Subject: [PATCH 05/19] flatten

---
 packages/sv/src/addons/common.ts | 75 +++++++++++---------------------
 1 file changed, 25 insertions(+), 50 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index 55b9e48ad..e829c2e1b 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -16,7 +16,7 @@ export function addEslintConfigPrettier(content: string): string {
 	let svelteImportName: string;
 	for (const specifier of sveltePluginImport?.specifiers ?? []) {
 		if (specifier.type === 'ImportDefaultSpecifier' && specifier.local?.name) {
-			svelteImportName = specifier.local.name as string;
+			svelteImportName = specifier.local.name;
 		}
 	}
 	svelteImportName ??= 'svelte';
@@ -41,64 +41,39 @@ export function addEslintConfigPrettier(content: string): string {
 	if (!js.common.contains(eslintConfig, sveltePrettierConfig))
 		nodesToInsert.push(sveltePrettierConfig);
 
+	// i dont know the type
+	const isSvelteConfig = (el: any) => {
+		const maybeSpread = el?.type === 'SpreadElement' ? el?.argument : el;
+		return (
+			maybeSpread?.object.type === 'MemberExpression' &&
+			maybeSpread.object.property.type === 'Identifier' &&
+			maybeSpread.object.property.name === 'configs' &&
+			maybeSpread.object.object.type === 'Identifier' &&
+			maybeSpread.object.object.name === svelteImportName
+		);
+	};
+
 	if (isDefineConfig) {
-		if (
-			eslintConfig.arguments.length === 1 &&
-			eslintConfig.arguments[0].type === 'ArrayExpression'
-		) {
-			// javascript - defineConfig([...])
-			const idx = eslintConfig.arguments[0].elements.findIndex(
-				(el) =>
-					el?.type === 'MemberExpression' &&
-					el.object.type === 'MemberExpression' &&
-					el.object.property.type === 'Identifier' &&
-					el.object.property.name === 'configs' &&
-					el.object.object.type === 'Identifier' &&
-					el.object.object.name === svelteImportName
-			);
-			if (idx !== -1) {
-				eslintConfig.arguments[0].elements.splice(idx + 1, 0, ...nodesToInsert);
-			} else {
-				// append to the end as a fallback
-				eslintConfig.arguments[0].elements.push(...nodesToInsert);
-			}
+		const container =
+			eslintConfig.arguments.length === 1 && eslintConfig.arguments[0].type === 'ArrayExpression'
+				? // javascript - defineConfig([...])
+					eslintConfig.arguments[0].elements
+				: // typescript - defineConfig(...)
+					eslintConfig.arguments;
+
+		const idx = container.findIndex(isSvelteConfig);
+		if (idx !== -1) {
+			container.splice(idx + 1, 0, ...nodesToInsert);
 		} else {
-			//typescript - defineConfig(...)
-			const idx = eslintConfig.arguments.findIndex(
-				(el) =>
-					el?.type === 'MemberExpression' &&
-					el.object.type === 'MemberExpression' &&
-					el.object.property.type === 'Identifier' &&
-					el.object.property.name === 'configs' &&
-					el.object.object.type === 'Identifier' &&
-					el.object.object.name === svelteImportName
-			);
-			if (idx !== -1) {
-				eslintConfig.arguments.splice(idx + 1, 0, ...nodesToInsert);
-			} else {
-				// append to the end as a fallback
-				eslintConfig.arguments.push(...nodesToInsert);
-			}
+			container.push(...nodesToInsert);
 		}
 	}
 
 	if (isArrayExport) {
-		// find index of `...svelte.configs["..."]`
-		const idx = eslintConfig.elements.findIndex(
-			(el) =>
-				el?.type === 'SpreadElement' &&
-				el.argument.type === 'MemberExpression' &&
-				el.argument.object.type === 'MemberExpression' &&
-				el.argument.object.property.type === 'Identifier' &&
-				el.argument.object.property.name === 'configs' &&
-				el.argument.object.object.type === 'Identifier' &&
-				el.argument.object.object.name === svelteImportName
-		);
-
+		const idx = eslintConfig.elements.findIndex(isSvelteConfig);
 		if (idx !== -1) {
 			eslintConfig.elements.splice(idx + 1, 0, ...nodesToInsert);
 		} else {
-			// append to the end as a fallback
 			eslintConfig.elements.push(...nodesToInsert);
 		}
 	}

From 5edfe5b5fcb7165d547e18c711ba4b8be9b6dddd Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 00:58:02 +0800
Subject: [PATCH 06/19] flatten

---
 packages/sv/src/addons/common.ts | 45 ++++++++++++++++----------------
 1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index e829c2e1b..02a9dcaee 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -45,37 +45,36 @@ export function addEslintConfigPrettier(content: string): string {
 	const isSvelteConfig = (el: any) => {
 		const maybeSpread = el?.type === 'SpreadElement' ? el?.argument : el;
 		return (
-			maybeSpread?.object.type === 'MemberExpression' &&
-			maybeSpread.object.property.type === 'Identifier' &&
-			maybeSpread.object.property.name === 'configs' &&
-			maybeSpread.object.object.type === 'Identifier' &&
-			maybeSpread.object.object.name === svelteImportName
+			maybeSpread?.object?.type === 'MemberExpression' &&
+			maybeSpread?.object?.property?.type === 'Identifier' &&
+			maybeSpread?.object?.property?.name === 'configs' &&
+			maybeSpread?.object?.object?.type === 'Identifier' &&
+			maybeSpread?.object?.object?.name === svelteImportName
 		);
 	};
 
+	// i dont know the type
+	let elements: any;
+	if (isArrayExport) elements = eslintConfig.elements;
+
 	if (isDefineConfig) {
-		const container =
-			eslintConfig.arguments.length === 1 && eslintConfig.arguments[0].type === 'ArrayExpression'
-				? // javascript - defineConfig([...])
-					eslintConfig.arguments[0].elements
-				: // typescript - defineConfig(...)
-					eslintConfig.arguments;
-
-		const idx = container.findIndex(isSvelteConfig);
-		if (idx !== -1) {
-			container.splice(idx + 1, 0, ...nodesToInsert);
+		if (
+			eslintConfig.arguments.length === 1 &&
+			eslintConfig.arguments[0].type === 'ArrayExpression'
+		) {
+			// javascript - defineConfig([...])
+			elements = eslintConfig.arguments[0].elements;
 		} else {
-			container.push(...nodesToInsert);
+			// typescript - defineConfig(...)
+			elements = eslintConfig.arguments;
 		}
 	}
 
-	if (isArrayExport) {
-		const idx = eslintConfig.elements.findIndex(isSvelteConfig);
-		if (idx !== -1) {
-			eslintConfig.elements.splice(idx + 1, 0, ...nodesToInsert);
-		} else {
-			eslintConfig.elements.push(...nodesToInsert);
-		}
+	const idx = elements.findIndex(isSvelteConfig);
+	if (idx !== -1) {
+		elements.splice(idx + 1, 0, ...nodesToInsert);
+	} else {
+		elements.push(...nodesToInsert);
 	}
 
 	return generateCode();

From a75694930464a25f55fa75310f902726c3667872 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 01:03:35 +0800
Subject: [PATCH 07/19] convert to `as string`

---
 packages/sv/src/addons/better-auth.ts | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/packages/sv/src/addons/better-auth.ts b/packages/sv/src/addons/better-auth.ts
index 1bc641059..5f3c4ad8f 100644
--- a/packages/sv/src/addons/better-auth.ts
+++ b/packages/sv/src/addons/better-auth.ts
@@ -241,8 +241,8 @@ export default defineAddon({
 						? `
 						signInEmail: async (event) => {
 							const formData = await event.request.formData();
-							const email = formData.get('email')?.toString() ?? '';
-							const password = formData.get('password')?.toString() ?? '';
+							const email = (formData.get('email') ?? '') as string;
+							const password = (formData.get('password') ?? '') as string;
 
 							try {
 								await auth.api.signInEmail({
@@ -263,9 +263,9 @@ export default defineAddon({
 						},
 						signUpEmail: async (event) => {
 							const formData = await event.request.formData();
-							const email = formData.get('email')?.toString() ?? '';
-							const password = formData.get('password')?.toString() ?? '';
-							const name = formData.get('name')?.toString() ?? '';
+							const email = (formData.get('email') ?? '') as string;
+							const password = (formData.get('password') ?? '') as string;
+							const name = (formData.get('name') ?? '') as string;
 
 							try {
 								await auth.api.signUpEmail({
@@ -291,8 +291,8 @@ export default defineAddon({
 						? `
 						signInSocial: async (event) => {
 							const formData = await event.request.formData();
-							const provider = formData.get('provider')?.toString() ?? 'github';
-							const callbackURL = formData.get('callbackURL')?.toString() ?? '/demo/better-auth';
+							const provider = (formData.get('provider') ?? 'github') as string;
+							const callbackURL = (formData.get('callbackURL') ?? '/demo/better-auth') as string;
 
 							const result = await auth.api.signInSocial({
 								body: {

From 9d82dc4542a2f975839c3ccdb2a10f2cbb1c7fc5 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 01:06:51 +0800
Subject: [PATCH 08/19] remove unused async

---
 packages/sv/src/addons/better-auth.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/sv/src/addons/better-auth.ts b/packages/sv/src/addons/better-auth.ts
index 5f3c4ad8f..ca8b54f8c 100644
--- a/packages/sv/src/addons/better-auth.ts
+++ b/packages/sv/src/addons/better-auth.ts
@@ -317,7 +317,7 @@ export default defineAddon({
 					import { auth } from '$lib/server/auth';
 					${needsAPIError ? "import { APIError } from 'better-auth/api';" : ''}
 
-					export const load${ts(': PageServerLoad')} = async (event) => {
+					export const load${ts(': PageServerLoad')} = (event) => {
 						if (event.locals.user) {
 							return redirect(302, '/demo/better-auth');
 						}
@@ -406,7 +406,7 @@ export default defineAddon({
 					${ts("import type { PageServerLoad } from './$types';")}
 					import { auth } from '$lib/server/auth';
 
-					export const load${ts(': PageServerLoad')} = async (event) => {
+					export const load${ts(': PageServerLoad')} = (event) => {
 						if (!event.locals.user) {
 							return redirect(302, '/demo/better-auth/login');
 						}

From 62495f44dba4dd0aba0c035afef07cddda2724a7 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Thu, 19 Mar 2026 01:14:00 +0800
Subject: [PATCH 09/19] update snapshot

---
 .../create-with-all-addons/eslint.config.js      |  5 +++++
 .../src/routes/demo/better-auth/+page.server.ts  |  2 +-
 .../demo/better-auth/login/+page.server.ts       | 16 ++++++++--------
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/packages/sv/src/cli/tests/snapshots/create-with-all-addons/eslint.config.js b/packages/sv/src/cli/tests/snapshots/create-with-all-addons/eslint.config.js
index bd3865858..2687e9fd1 100644
--- a/packages/sv/src/cli/tests/snapshots/create-with-all-addons/eslint.config.js
+++ b/packages/sv/src/cli/tests/snapshots/create-with-all-addons/eslint.config.js
@@ -35,5 +35,10 @@ export default defineConfig(
 				svelteConfig
 			}
 		}
+	},
+	{
+		// Override or add rule settings here, such as:
+		// 'svelte/rule-name': 'error'
+		rules: {}
 	}
 );
diff --git a/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/+page.server.ts b/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/+page.server.ts
index 7c3083543..92a1f2ec3 100644
--- a/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/+page.server.ts
+++ b/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/+page.server.ts
@@ -3,7 +3,7 @@ import type { Actions } from './$types';
 import type { PageServerLoad } from './$types';
 import { auth } from '$lib/server/auth';
 
-export const load: PageServerLoad = async (event) => {
+export const load: PageServerLoad = (event) => {
 	if (!event.locals.user) {
 		return redirect(302, '/demo/better-auth/login');
 	}
diff --git a/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/login/+page.server.ts b/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/login/+page.server.ts
index 2ddbc0e7c..e5f3c649d 100644
--- a/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/login/+page.server.ts
+++ b/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/login/+page.server.ts
@@ -4,7 +4,7 @@ import type { PageServerLoad } from './$types';
 import { auth } from '$lib/server/auth';
 import { APIError } from 'better-auth/api';
 
-export const load: PageServerLoad = async (event) => {
+export const load: PageServerLoad = (event) => {
 	if (event.locals.user) {
 		return redirect(302, '/demo/better-auth');
 	}
@@ -14,8 +14,8 @@ export const load: PageServerLoad = async (event) => {
 export const actions: Actions = {
 	signInEmail: async (event) => {
 		const formData = await event.request.formData();
-		const email = formData.get('email')?.toString() ?? '';
-		const password = formData.get('password')?.toString() ?? '';
+		const email = (formData.get('email') ?? '') as string;
+		const password = (formData.get('password') ?? '') as string;
 
 		try {
 			await auth.api.signInEmail({
@@ -36,9 +36,9 @@ export const actions: Actions = {
 	},
 	signUpEmail: async (event) => {
 		const formData = await event.request.formData();
-		const email = formData.get('email')?.toString() ?? '';
-		const password = formData.get('password')?.toString() ?? '';
-		const name = formData.get('name')?.toString() ?? '';
+		const email = (formData.get('email') ?? '') as string;
+		const password = (formData.get('password') ?? '') as string;
+		const name = (formData.get('name') ?? '') as string;
 
 		try {
 			await auth.api.signUpEmail({
@@ -60,8 +60,8 @@ export const actions: Actions = {
 	},
 	signInSocial: async (event) => {
 		const formData = await event.request.formData();
-		const provider = formData.get('provider')?.toString() ?? 'github';
-		const callbackURL = formData.get('callbackURL')?.toString() ?? '/demo/better-auth';
+		const provider = (formData.get('provider') ?? 'github') as string;
+		const callbackURL = (formData.get('callbackURL') ?? '/demo/better-auth') as string;
 
 		const result = await auth.api.signInSocial({
 			body: {

From 9b2005ad03c6f72ade000805a4a0f01147412ee3 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Sat, 21 Mar 2026 13:10:04 +0800
Subject: [PATCH 10/19] comments are important

---
 packages/sv/src/addons/common.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index 02a9dcaee..eb9115631 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -74,6 +74,7 @@ export function addEslintConfigPrettier(content: string): string {
 	if (idx !== -1) {
 		elements.splice(idx + 1, 0, ...nodesToInsert);
 	} else {
+		// append to the end as a fallback
 		elements.push(...nodesToInsert);
 	}
 

From d6e276c59699914d851fd1c1a2e434a23090523f Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Tue, 24 Mar 2026 14:15:59 +0800
Subject: [PATCH 11/19] fix types

---
 packages/sv/src/addons/common.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index eb9115631..35df14288 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -42,9 +42,10 @@ export function addEslintConfigPrettier(content: string): string {
 		nodesToInsert.push(sveltePrettierConfig);
 
 	// i dont know the type
-	const isSvelteConfig = (el: any) => {
+	const isSvelteConfig = (el: js.AstTypes.Expression | js.AstTypes.SpreadElement | null) => {
 		const maybeSpread = el?.type === 'SpreadElement' ? el?.argument : el;
 		return (
+			maybeSpread?.type === 'MemberExpression' &&
 			maybeSpread?.object?.type === 'MemberExpression' &&
 			maybeSpread?.object?.property?.type === 'Identifier' &&
 			maybeSpread?.object?.property?.name === 'configs' &&
@@ -54,7 +55,7 @@ export function addEslintConfigPrettier(content: string): string {
 	};
 
 	// i dont know the type
-	let elements: any;
+	let elements: Array<js.AstTypes.Expression | js.AstTypes.SpreadElement | null> = [];
 	if (isArrayExport) elements = eslintConfig.elements;
 
 	if (isDefineConfig) {

From 110e74629c8c7761d093aad540f0401a217a86fb Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Tue, 24 Mar 2026 15:05:29 +0800
Subject: [PATCH 12/19] fix again

---
 packages/sv/src/addons/common.ts | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index 35df14288..054b705b1 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -33,6 +33,9 @@ export function addEslintConfigPrettier(content: string): string {
 
 	if (!isArrayExport && !isDefineConfig) return content;
 
+	type Arguments = Extract<typeof eslintConfig, { type: 'CallExpression' }>['arguments'];
+	type Elements = Extract<typeof eslintConfig, { type: 'ArrayExpression' }>['elements'];
+
 	const prettier = js.common.parseExpression('prettier');
 	const sveltePrettierConfig = js.common.parseExpression(`${svelteImportName}.configs.prettier`);
 
@@ -41,8 +44,7 @@ export function addEslintConfigPrettier(content: string): string {
 	if (!js.common.contains(eslintConfig, sveltePrettierConfig))
 		nodesToInsert.push(sveltePrettierConfig);
 
-	// i dont know the type
-	const isSvelteConfig = (el: js.AstTypes.Expression | js.AstTypes.SpreadElement | null) => {
+	const isSvelteConfig = (el: (Arguments | Elements)[number]) => {
 		const maybeSpread = el?.type === 'SpreadElement' ? el?.argument : el;
 		return (
 			maybeSpread?.type === 'MemberExpression' &&
@@ -54,8 +56,7 @@ export function addEslintConfigPrettier(content: string): string {
 		);
 	};
 
-	// i dont know the type
-	let elements: Array<js.AstTypes.Expression | js.AstTypes.SpreadElement | null> = [];
+	let elements: Arguments | Elements = [];
 	if (isArrayExport) elements = eslintConfig.elements;
 
 	if (isDefineConfig) {

From 056f90dc3c4d26f56ea8d840d5bbea6a8c71fbe5 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Tue, 24 Mar 2026 15:19:00 +0800
Subject: [PATCH 13/19] no more `as string`

---
 packages/sv/src/addons/better-auth.ts | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/packages/sv/src/addons/better-auth.ts b/packages/sv/src/addons/better-auth.ts
index ca8b54f8c..e22272fa6 100644
--- a/packages/sv/src/addons/better-auth.ts
+++ b/packages/sv/src/addons/better-auth.ts
@@ -241,8 +241,8 @@ export default defineAddon({
 						? `
 						signInEmail: async (event) => {
 							const formData = await event.request.formData();
-							const email = (formData.get('email') ?? '') as string;
-							const password = (formData.get('password') ?? '') as string;
+							const email = typeof formData.get('email') === 'string') ? formData.get('email') : '';
+							const password = typeof formData.get('password') === 'string') ? formData.get('password') : '';
 
 							try {
 								await auth.api.signInEmail({
@@ -263,9 +263,9 @@ export default defineAddon({
 						},
 						signUpEmail: async (event) => {
 							const formData = await event.request.formData();
-							const email = (formData.get('email') ?? '') as string;
-							const password = (formData.get('password') ?? '') as string;
-							const name = (formData.get('name') ?? '') as string;
+							const email = typeof formData.get('email') === 'string') ? formData.get('email') : '';
+							const password = typeof formData.get('password') === 'string') ? formData.get('password') : '';
+							const name = typeof formData.get('name') === 'string') ? formData.get('name') : '';
 
 							try {
 								await auth.api.signUpEmail({
@@ -291,8 +291,9 @@ export default defineAddon({
 						? `
 						signInSocial: async (event) => {
 							const formData = await event.request.formData();
-							const provider = (formData.get('provider') ?? 'github') as string;
-							const callbackURL = (formData.get('callbackURL') ?? '/demo/better-auth') as string;
+              
+							const provider = typeof formData.get('provider') === 'string') ? formData.get('provider') : 'github';
+							const callbackURL = typeof formData.get('callbackURL') === 'string') ? formData.get('callbackURL') : '/demo/better-auth';
 
 							const result = await auth.api.signInSocial({
 								body: {

From 132cf17c08d732a96cbb94938da16047b4b251ae Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Tue, 24 Mar 2026 15:26:45 +0800
Subject: [PATCH 14/19] .

---
 packages/sv/src/addons/better-auth.ts | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/packages/sv/src/addons/better-auth.ts b/packages/sv/src/addons/better-auth.ts
index e22272fa6..e2f714fb7 100644
--- a/packages/sv/src/addons/better-auth.ts
+++ b/packages/sv/src/addons/better-auth.ts
@@ -241,8 +241,8 @@ export default defineAddon({
 						? `
 						signInEmail: async (event) => {
 							const formData = await event.request.formData();
-							const email = typeof formData.get('email') === 'string') ? formData.get('email') : '';
-							const password = typeof formData.get('password') === 'string') ? formData.get('password') : '';
+							const email = typeof formData.get('email') === 'string' ? formData.get('email') : '';
+							const password = typeof formData.get('password') === 'string' ? formData.get('password') : '';
 
 							try {
 								await auth.api.signInEmail({
@@ -263,9 +263,9 @@ export default defineAddon({
 						},
 						signUpEmail: async (event) => {
 							const formData = await event.request.formData();
-							const email = typeof formData.get('email') === 'string') ? formData.get('email') : '';
+							const email = typeof formData.get('email') === 'string' ? formData.get('email') : '';
 							const password = typeof formData.get('password') === 'string') ? formData.get('password') : '';
-							const name = typeof formData.get('name') === 'string') ? formData.get('name') : '';
+							const name = typeof formData.get('name') === 'string' ? formData.get('name') : '';
 
 							try {
 								await auth.api.signUpEmail({
@@ -292,8 +292,8 @@ export default defineAddon({
 						signInSocial: async (event) => {
 							const formData = await event.request.formData();
               
-							const provider = typeof formData.get('provider') === 'string') ? formData.get('provider') : 'github';
-							const callbackURL = typeof formData.get('callbackURL') === 'string') ? formData.get('callbackURL') : '/demo/better-auth';
+							const provider = typeof formData.get('provider') === 'string' ? formData.get('provider') : 'github';
+							const callbackURL = typeof formData.get('callbackURL') === 'string' ? formData.get('callbackURL') : '/demo/better-auth';
 
 							const result = await auth.api.signInSocial({
 								body: {

From 21e3b26accecf93a49af0230c77d9c41f2be09c2 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Sat, 28 Mar 2026 21:16:05 +0800
Subject: [PATCH 15/19] .

---
 packages/sv/src/addons/better-auth.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/sv/src/addons/better-auth.ts b/packages/sv/src/addons/better-auth.ts
index e2f714fb7..fe6533a45 100644
--- a/packages/sv/src/addons/better-auth.ts
+++ b/packages/sv/src/addons/better-auth.ts
@@ -264,7 +264,7 @@ export default defineAddon({
 						signUpEmail: async (event) => {
 							const formData = await event.request.formData();
 							const email = typeof formData.get('email') === 'string' ? formData.get('email') : '';
-							const password = typeof formData.get('password') === 'string') ? formData.get('password') : '';
+							const password = typeof formData.get('password') === 'string' ? formData.get('password') : '';
 							const name = typeof formData.get('name') === 'string' ? formData.get('name') : '';
 
 							try {

From 211f34b52245d7f84076399e276b9478e7d3d859 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Sat, 28 Mar 2026 21:38:47 +0800
Subject: [PATCH 16/19] snapshot

---
 .../routes/demo/better-auth/login/+page.server.ts | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/login/+page.server.ts b/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/login/+page.server.ts
index e5f3c649d..4a884034a 100644
--- a/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/login/+page.server.ts
+++ b/packages/sv/src/cli/tests/snapshots/create-with-all-addons/src/routes/demo/better-auth/login/+page.server.ts
@@ -14,8 +14,8 @@ export const load: PageServerLoad = (event) => {
 export const actions: Actions = {
 	signInEmail: async (event) => {
 		const formData = await event.request.formData();
-		const email = (formData.get('email') ?? '') as string;
-		const password = (formData.get('password') ?? '') as string;
+		const email = typeof formData.get('email') === 'string' ? formData.get('email') : '';
+		const password = typeof formData.get('password') === 'string' ? formData.get('password') : '';
 
 		try {
 			await auth.api.signInEmail({
@@ -36,9 +36,9 @@ export const actions: Actions = {
 	},
 	signUpEmail: async (event) => {
 		const formData = await event.request.formData();
-		const email = (formData.get('email') ?? '') as string;
-		const password = (formData.get('password') ?? '') as string;
-		const name = (formData.get('name') ?? '') as string;
+		const email = typeof formData.get('email') === 'string' ? formData.get('email') : '';
+		const password = typeof formData.get('password') === 'string' ? formData.get('password') : '';
+		const name = typeof formData.get('name') === 'string' ? formData.get('name') : '';
 
 		try {
 			await auth.api.signUpEmail({
@@ -60,8 +60,9 @@ export const actions: Actions = {
 	},
 	signInSocial: async (event) => {
 		const formData = await event.request.formData();
-		const provider = (formData.get('provider') ?? 'github') as string;
-		const callbackURL = (formData.get('callbackURL') ?? '/demo/better-auth') as string;
+         
+		const provider = typeof formData.get('provider') === 'string' ? formData.get('provider') : 'github';
+		const callbackURL = typeof formData.get('callbackURL') === 'string' ? formData.get('callbackURL') : '/demo/better-auth';
 
 		const result = await auth.api.signInSocial({
 			body: {

From 5a9438a529a68e2d6db684794893fdf580933c56 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Sat, 28 Mar 2026 21:58:39 +0800
Subject: [PATCH 17/19] nit

---
 packages/sv/src/addons/common.ts | 37 ++++++++++++++++----------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index 054b705b1..a11387fa5 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -29,12 +29,13 @@ export function addEslintConfigPrettier(content: string): string {
 	const eslintConfig = defaultExport.value;
 
 	const isDefineConfig = eslintConfig.type === 'CallExpression'; // export default defineConfig()
-	const isArrayExport = eslintConfig.type === 'ArrayExpression'; // export default []
+	const isArray = eslintConfig.type === 'ArrayExpression'; // export default []
 
-	if (!isArrayExport && !isDefineConfig) return content;
+	if (!isArray && !isDefineConfig) return content;
 
-	type Arguments = Extract<typeof eslintConfig, { type: 'CallExpression' }>['arguments'];
-	type Elements = Extract<typeof eslintConfig, { type: 'ArrayExpression' }>['elements'];
+	type Elements =
+		| Extract<typeof eslintConfig, { type: 'CallExpression' }>['arguments']
+		| Extract<typeof eslintConfig, { type: 'ArrayExpression' }>['elements'];
 
 	const prettier = js.common.parseExpression('prettier');
 	const sveltePrettierConfig = js.common.parseExpression(`${svelteImportName}.configs.prettier`);
@@ -44,20 +45,8 @@ export function addEslintConfigPrettier(content: string): string {
 	if (!js.common.contains(eslintConfig, sveltePrettierConfig))
 		nodesToInsert.push(sveltePrettierConfig);
 
-	const isSvelteConfig = (el: (Arguments | Elements)[number]) => {
-		const maybeSpread = el?.type === 'SpreadElement' ? el?.argument : el;
-		return (
-			maybeSpread?.type === 'MemberExpression' &&
-			maybeSpread?.object?.type === 'MemberExpression' &&
-			maybeSpread?.object?.property?.type === 'Identifier' &&
-			maybeSpread?.object?.property?.name === 'configs' &&
-			maybeSpread?.object?.object?.type === 'Identifier' &&
-			maybeSpread?.object?.object?.name === svelteImportName
-		);
-	};
-
-	let elements: Arguments | Elements = [];
-	if (isArrayExport) elements = eslintConfig.elements;
+	let elements: Elements = [];
+	if (isArray) elements = eslintConfig.elements;
 
 	if (isDefineConfig) {
 		if (
@@ -72,6 +61,18 @@ export function addEslintConfigPrettier(content: string): string {
 		}
 	}
 
+	const isSvelteConfig = (maybeSpread: Elements[number]) => {
+		const el = maybeSpread?.type === 'SpreadElement' ? maybeSpread?.argument : maybeSpread;
+		return (
+			el &&
+			el.type === 'MemberExpression' &&
+			el.object.type === 'MemberExpression' &&
+			el.object.object.type === 'Identifier' &&
+			el.object.object.name === svelteImportName &&
+			el.object.property.type === 'Identifier' &&
+			el.object.property.name === 'configs'
+		);
+	};
 	const idx = elements.findIndex(isSvelteConfig);
 	if (idx !== -1) {
 		elements.splice(idx + 1, 0, ...nodesToInsert);

From f6bfca552a2af0dbd4beef4844f8602804ed22e2 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Sat, 28 Mar 2026 22:18:32 +0800
Subject: [PATCH 18/19] comment

---
 packages/sv/src/addons/common.ts | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index a11387fa5..f4921c82c 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -62,13 +62,19 @@ export function addEslintConfigPrettier(content: string): string {
 	}
 
 	const isSvelteConfig = (maybeSpread: Elements[number]) => {
-		const el = maybeSpread?.type === 'SpreadElement' ? maybeSpread?.argument : maybeSpread;
+		const el =
+			maybeSpread?.type === 'SpreadElement'
+				? // ...svelte.configs.*
+					maybeSpread?.argument
+				: // svelte.configs.*
+					maybeSpread;
 		return (
-			el &&
-			el.type === 'MemberExpression' &&
+			el?.type === 'MemberExpression' &&
 			el.object.type === 'MemberExpression' &&
+			// Check for [svelte].configs.*
 			el.object.object.type === 'Identifier' &&
 			el.object.object.name === svelteImportName &&
+			// Check for svelte.[configs].*
 			el.object.property.type === 'Identifier' &&
 			el.object.property.name === 'configs'
 		);

From c047c10a5b690fbc6f0660c5e8bc74e5f09d6431 Mon Sep 17 00:00:00 2001
From: Scott Wu <sw@scottwu.ca>
Date: Sat, 28 Mar 2026 22:30:03 +0800
Subject: [PATCH 19/19] refactor

---
 packages/sv/src/addons/common.ts | 34 ++++++++++++++++----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/packages/sv/src/addons/common.ts b/packages/sv/src/addons/common.ts
index f4921c82c..beba5ae6d 100644
--- a/packages/sv/src/addons/common.ts
+++ b/packages/sv/src/addons/common.ts
@@ -28,39 +28,39 @@ export function addEslintConfigPrettier(content: string): string {
 	const defaultExport = js.exports.createDefault(ast, { fallback: fallbackConfig });
 	const eslintConfig = defaultExport.value;
 
-	const isDefineConfig = eslintConfig.type === 'CallExpression'; // export default defineConfig()
-	const isArray = eslintConfig.type === 'ArrayExpression'; // export default []
-
-	if (!isArray && !isDefineConfig) return content;
-
 	type Elements =
 		| Extract<typeof eslintConfig, { type: 'CallExpression' }>['arguments']
 		| Extract<typeof eslintConfig, { type: 'ArrayExpression' }>['elements'];
 
-	const prettier = js.common.parseExpression('prettier');
-	const sveltePrettierConfig = js.common.parseExpression(`${svelteImportName}.configs.prettier`);
-
-	const nodesToInsert = [];
-	if (!js.common.contains(eslintConfig, prettier)) nodesToInsert.push(prettier);
-	if (!js.common.contains(eslintConfig, sveltePrettierConfig))
-		nodesToInsert.push(sveltePrettierConfig);
-
 	let elements: Elements = [];
-	if (isArray) elements = eslintConfig.elements;
 
-	if (isDefineConfig) {
+	if (eslintConfig.type === 'ArrayExpression') {
+		// export default []
+		elements = eslintConfig.elements;
+	} else if (eslintConfig.type === 'CallExpression') {
 		if (
 			eslintConfig.arguments.length === 1 &&
 			eslintConfig.arguments[0].type === 'ArrayExpression'
 		) {
-			// javascript - defineConfig([...])
+			// export default defineConfig([...])
 			elements = eslintConfig.arguments[0].elements;
 		} else {
-			// typescript - defineConfig(...)
+			// export default defineConfig({}, {})
 			elements = eslintConfig.arguments;
 		}
+	} else {
+		// fallback: Not an array or a function call
+		return content;
 	}
 
+	const prettier = js.common.parseExpression('prettier');
+	const sveltePrettierConfig = js.common.parseExpression(`${svelteImportName}.configs.prettier`);
+
+	const nodesToInsert = [];
+	if (!js.common.contains(eslintConfig, prettier)) nodesToInsert.push(prettier);
+	if (!js.common.contains(eslintConfig, sveltePrettierConfig))
+		nodesToInsert.push(sveltePrettierConfig);
+
 	const isSvelteConfig = (maybeSpread: Elements[number]) => {
 		const el =
 			maybeSpread?.type === 'SpreadElement'