fix: implement persistent MongoDB connections and resolve race conditions

- Replace connect/disconnect pattern with persistent connection pool
- Add explicit database initialization on server startup
- Remove all dbDisconnect() calls from API endpoints to prevent race conditions
- Fix MongoNotConnectedError when scheduler runs concurrently with API requests
- Add connection pooling with proper MongoDB driver options
- Add safety check for recipes array in favorites utility

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/routes/api/rezepte/add/+server.ts

@@ -1,6 +1,6 @@
 import type { RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../utils/db';
+import { dbConnect } from '../../../../utils/db';
 import { error } from '@sveltejs/kit';
 // header: use for bearer token for now
 // recipe json in body
@@ -22,7 +22,6 @@ export const POST: RequestHandler = async ({request, cookies, locals}) => {
 	} catch(e){
       		throw error(400, e)
       	}
-	await dbDisconnect();
       	return new Response(JSON.stringify({msg: "Added recipe successfully"}),{
       		    status: 200,
 	});

src/routes/api/rezepte/delete/+server.ts

@@ -1,6 +1,6 @@
 import type { RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../utils/db';
+import { dbConnect } from '../../../../utils/db';
 import type {RecipeModelType} from '../../../../types/types';
 import { error } from '@sveltejs/kit';
 // header: use for bearer token for now
@@ -14,7 +14,6 @@ export const POST: RequestHandler = async ({request, locals}) => {
   	const short_name = message.old_short_name
 	await dbConnect();
 	await Recipe.findOneAndDelete({short_name: short_name});
-  	await dbDisconnect();
 	return new Response(JSON.stringify({msg: "Deleted recipe successfully"}),{
 			    status: 200,
   	});

src/routes/api/rezepte/edit/+server.ts

@@ -1,6 +1,6 @@
 import type { RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../utils/db';
+import { dbConnect } from '../../../../utils/db';
 import type {RecipeModelType} from '../../../../types/types';
 import { error } from '@sveltejs/kit';
 // header: use for bearer token for now
@@ -15,7 +15,6 @@ export const POST: RequestHandler = async ({request, locals}) => {
   else{
 	await dbConnect();
 	await Recipe.findOneAndUpdate({short_name: message.old_short_name }, recipe_json);
-  	await dbDisconnect();
 	return new Response(JSON.stringify({msg: "Edited recipe successfully"}),{
 			    status: 200,
   	});

src/routes/api/rezepte/favorites/+server.ts

@@ -1,7 +1,7 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { UserFavorites } from '../../../../models/UserFavorites';
 import { Recipe } from '../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../utils/db';
+import { dbConnect } from '../../../../utils/db';
 import { error } from '@sveltejs/kit';
 import mongoose from 'mongoose';
 
@@ -19,13 +19,11 @@ export const GET: RequestHandler = async ({ locals }) => {
       username: session.user.nickname 
     }).lean();
     
-    await dbDisconnect();
     
     return json({
       favorites: userFavorites?.favorites || []
     });
   } catch (e) {
-    await dbDisconnect();
     throw error(500, 'Failed to fetch favorites');
   }
 };
@@ -49,8 +47,7 @@ export const POST: RequestHandler = async ({ request, locals }) => {
     // Validate that the recipe exists and get its ObjectId
     const recipe = await Recipe.findOne({ short_name: recipeId });
     if (!recipe) {
-      await dbDisconnect();
-      throw error(404, 'Recipe not found');
+        throw error(404, 'Recipe not found');
     }
     
     await UserFavorites.findOneAndUpdate(
@@ -59,11 +56,9 @@ export const POST: RequestHandler = async ({ request, locals }) => {
       { upsert: true, new: true }
     );
     
-    await dbDisconnect();
     
     return json({ success: true });
   } catch (e) {
-    await dbDisconnect();
     if (e instanceof Error && e.message.includes('404')) {
       throw e;
     }
@@ -90,8 +85,7 @@ export const DELETE: RequestHandler = async ({ request, locals }) => {
     // Find the recipe's ObjectId
     const recipe = await Recipe.findOne({ short_name: recipeId });
     if (!recipe) {
-      await dbDisconnect();
-      throw error(404, 'Recipe not found');
+        throw error(404, 'Recipe not found');
     }
     
     await UserFavorites.findOneAndUpdate(
@@ -99,11 +93,9 @@ export const DELETE: RequestHandler = async ({ request, locals }) => {
       { $pull: { favorites: recipe._id } }
     );
     
-    await dbDisconnect();
     
     return json({ success: true });
   } catch (e) {
-    await dbDisconnect();
     if (e instanceof Error && e.message.includes('404')) {
       throw e;
     }

src/routes/api/rezepte/favorites/check/[shortName]/+server.ts

@@ -1,7 +1,7 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { UserFavorites } from '../../../../../../models/UserFavorites';
 import { Recipe } from '../../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../../utils/db';
+import { dbConnect } from '../../../../../../utils/db';
 import { error } from '@sveltejs/kit';
 
 export const GET: RequestHandler = async ({ locals, params }) => {
@@ -17,7 +17,6 @@ export const GET: RequestHandler = async ({ locals, params }) => {
     // Find the recipe by short_name to get its ObjectId
     const recipe = await Recipe.findOne({ short_name: params.shortName });
     if (!recipe) {
-      await dbDisconnect();
       throw error(404, 'Recipe not found');
     }
     
@@ -27,13 +26,11 @@ export const GET: RequestHandler = async ({ locals, params }) => {
       favorites: recipe._id
     }).lean();
     
-    await dbDisconnect();
     
     return json({
       isFavorite: !!userFavorites
     });
   } catch (e) {
-    await dbDisconnect();
     if (e instanceof Error && e.message.includes('404')) {
       throw e;
     }

src/routes/api/rezepte/favorites/recipes/+server.ts

@@ -1,7 +1,7 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { UserFavorites } from '../../../../../models/UserFavorites';
 import { Recipe } from '../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import { dbConnect } from '../../../../../utils/db';
 import type { RecipeModelType } from '../../../../../types/types';
 import { error } from '@sveltejs/kit';
 
@@ -20,7 +20,6 @@ export const GET: RequestHandler = async ({ locals }) => {
     }).lean();
     
     if (!userFavorites?.favorites?.length) {
-      await dbDisconnect();
       return json([]);
     }
     
@@ -28,13 +27,11 @@ export const GET: RequestHandler = async ({ locals }) => {
       _id: { $in: userFavorites.favorites }
     }).lean() as RecipeModelType[];
     
-    await dbDisconnect();
     
     recipes = JSON.parse(JSON.stringify(recipes));
     
     return json(recipes);
   } catch (e) {
-    await dbDisconnect();
     throw error(500, 'Failed to fetch favorite recipes');
   }
 };

src/routes/api/rezepte/items/[name]/+server.ts

@@ -1,13 +1,12 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import { dbConnect } from '../../../../../utils/db';
 import type {RecipeModelType} from '../../../../../types/types';
 import { error } from '@sveltejs/kit';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let recipe = (await Recipe.findOne({ short_name: params.name}).lean()) as RecipeModelType[];
-  await dbDisconnect();
 
   recipe = JSON.parse(JSON.stringify(recipe));
   if(recipe == null){

src/routes/api/rezepte/items/all_brief/+server.ts

@@ -1,12 +1,11 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import type { BriefRecipeType } from '../../../../../types/types';
 import { Recipe } from '../../../../../models/Recipe'
-import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import { dbConnect } from '../../../../../utils/db';
 import { rand_array } from '$lib/js/randomize';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let found_brief = rand_array(await Recipe.find({}, 'name short_name tags category icon description season dateModified').lean()) as BriefRecipeType[];
-  await dbDisconnect();
   return json(JSON.parse(JSON.stringify(found_brief)));
 };

src/routes/api/rezepte/items/category/+server.ts

@@ -1,12 +1,11 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import { dbConnect } from '../../../../../utils/db';
 import type {BriefRecipeType} from '../../../../../types/types';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let categories = (await Recipe.distinct('category').lean());
-  await dbDisconnect();
 
   categories= JSON.parse(JSON.stringify(categories));
   return json(categories);

src/routes/api/rezepte/items/category/[category]/+server.ts

@@ -1,13 +1,12 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../../utils/db';
+import { dbConnect } from '../../../../../../utils/db';
 import type {BriefRecipeType} from '../../../../../../types/types';
 import { rand_array } from '$lib/js/randomize';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let recipes = rand_array(await Recipe.find({category: params.category}, 'name short_name images tags category icon description season dateModified').lean()) as BriefRecipeType[];
-  await dbDisconnect();
 
   recipes = JSON.parse(JSON.stringify(recipes));
   return json(recipes);

src/routes/api/rezepte/items/icon/+server.ts

@@ -1,12 +1,11 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import { dbConnect } from '../../../../../utils/db';
 import type {BriefRecipeType} from '../../../../../types/types';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let icons = (await Recipe.distinct('icon').lean());
-  await dbDisconnect();
 
   icons = JSON.parse(JSON.stringify(icons));
   return json(icons);

src/routes/api/rezepte/items/icon/[icon]/+server.ts

@@ -1,13 +1,12 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../../utils/db';
+import { dbConnect } from '../../../../../../utils/db';
 import type {BriefRecipeType} from '../../../../../../types/types';
 import { rand_array } from '$lib/js/randomize';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let recipes = rand_array(await Recipe.find({icon: params.icon}, 'name short_name images tags category icon description season dateModified').lean()) as BriefRecipeType[];
-  await dbDisconnect();
 
   recipes = JSON.parse(JSON.stringify(recipes));
   return json(recipes);

src/routes/api/rezepte/items/in_season/[month]/+server.ts

@@ -1,13 +1,12 @@
 import type {rand_array} from '$lib/js/randomize';
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../../models/Recipe'
-import { dbConnect, dbDisconnect } from '../../../../../../utils/db';
+import { dbConnect } from '../../../../../../utils/db';
 import { rand_array } from '$lib/js/randomize';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let found_in_season = rand_array(await Recipe.find({season: params.month, icon: {$ne: "🍽️"}}, 'name short_name images tags category icon description season dateModified').lean());
-  await dbDisconnect();
   found_in_season = JSON.parse(JSON.stringify(found_in_season));
   return json(found_in_season);
 };

src/routes/api/rezepte/items/tag/+server.ts

@@ -1,12 +1,11 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import { dbConnect } from '../../../../../utils/db';
 import type {BriefRecipeType} from '../../../../../types/types';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let categories = (await Recipe.distinct('tags').lean());
-  await dbDisconnect();
 
   categories= JSON.parse(JSON.stringify(categories));
   return json(categories);

src/routes/api/rezepte/items/tag/[tag]/+server.ts

@@ -1,13 +1,12 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../../utils/db';
+import { dbConnect } from '../../../../../../utils/db';
 import type {BriefRecipeType} from '../../../../../../types/types';
 import { rand_array } from '$lib/js/randomize';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
   let recipes = rand_array(await Recipe.find({tags: params.tag}, 'name short_name images tags category icon description season dateModified').lean()) as BriefRecipeType[];
-  await dbDisconnect();
 
   recipes = JSON.parse(JSON.stringify(recipes));
   return json(recipes);

src/routes/api/rezepte/json-ld/[name]/+server.ts

@@ -1,6 +1,6 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import { Recipe } from '../../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../../utils/db';
+import { dbConnect } from '../../../../../utils/db';
 import { generateRecipeJsonLd } from '$lib/js/recipeJsonLd';
 import type { RecipeModelType } from '../../../../../types/types';
 import { error } from '@sveltejs/kit';
@@ -8,7 +8,6 @@ import { error } from '@sveltejs/kit';
 export const GET: RequestHandler = async ({ params, setHeaders }) => {
   await dbConnect();
   let recipe = (await Recipe.findOne({ short_name: params.name }).lean()) as RecipeModelType;
-  await dbDisconnect();
 
   recipe = JSON.parse(JSON.stringify(recipe));
   if (recipe == null) {

src/routes/api/rezepte/search/+server.ts

@@ -1,7 +1,7 @@
 import { json, type RequestHandler } from '@sveltejs/kit';
 import type { BriefRecipeType } from '../../../../types/types';
 import { Recipe } from '../../../../models/Recipe';
-import { dbConnect, dbDisconnect } from '../../../../utils/db';
+import { dbConnect } from '../../../../utils/db';
 
 export const GET: RequestHandler = async ({ url, locals }) => {
   await dbConnect();
@@ -64,11 +64,9 @@ export const GET: RequestHandler = async ({ url, locals }) => {
       });
     }
     
-    await dbDisconnect();
     return json(JSON.parse(JSON.stringify(recipes)));
     
   } catch (error) {
-    await dbDisconnect();
     return json({ error: 'Search failed' }, { status: 500 });
   }
 };