diff --git a/CLAUDE.md b/CLAUDE.md
index 2ed968b..1e4499a 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -46,7 +46,7 @@ index.js (startup)
   ├── runMigrations()
   ├── getProviders()            # lazily imports lib/provider/*.js
   ├── similarityCache.init()    # preloads hash cache from DB
-  ├── api.js                    # starts restana HTTP server
+  ├── api.js                    # starts fastify HTTP server
   └── initJobExecutionService() # registers event-bus listeners + starts scheduler
 
 scheduler (every N minutes) or manual trigger via POST /api/jobs/:id/run
diff --git a/lib/FredyPipelineExecutioner.js b/lib/FredyPipelineExecutioner.js
index 35fc73c..b586d77 100755
--- a/lib/FredyPipelineExecutioner.js
+++ b/lib/FredyPipelineExecutioner.js
@@ -264,10 +264,12 @@ class FredyPipelineExecutioner {
       listings
         // this should never filter some listings out, because the normalize function should always extract all fields.
         .filter((item) => requiredKeys.every((key) => key in item))
+        // Drop listings missing a required identifying field *before* the provider
+        // filter runs, so provider filter functions never have to defend against a
+        // null id/link/title.
+        .filter((item) => requireValues.every((key) => item[key] != null))
         // TODO: move blacklist filter to this file, so it will handle for all providers in same way.
         .filter(this._providerConfig.filter)
-        // filter out listings that are missing required fields
-        .filter((item) => requireValues.every((key) => item[key] != null))
     );
   }
 
@@ -322,9 +324,9 @@ class FredyPipelineExecutioner {
    */
   _findNew(listings) {
     logger.debug(`Checking ${listings.length} listings for new entries (Provider: '${this._providerId}')`);
-    const hashes = getKnownListingHashesForJobAndProvider(this._jobKey, this._providerId) || [];
+    const knownHashes = new Set(getKnownListingHashesForJobAndProvider(this._jobKey, this._providerId) || []);
 
-    const newListings = listings.filter((o) => !hashes.includes(o.id));
+    const newListings = listings.filter((o) => !knownHashes.has(o.id));
     if (newListings.length === 0) {
       throw new NoNewListingsWarning();
     }
diff --git a/lib/provider/einsAImmobilien.js b/lib/provider/einsAImmobilien.js
index 771ae8e..06d8315 100755
--- a/lib/provider/einsAImmobilien.js
+++ b/lib/provider/einsAImmobilien.js
@@ -20,7 +20,7 @@ function normalize(o) {
   const link = `${baseUrl}/expose/${o.id}.html`;
   const price = normalizePrice(o.price);
   const id = buildHash(o.id, price);
-  const image = baseUrl + o.image;
+  const image = o.image == null ? null : baseUrl + o.image;
   const address = o.address == null ? null : o.address.trim().replaceAll('/', ',');
   return {
     id,
diff --git a/lib/provider/mcMakler.js b/lib/provider/mcMakler.js
index 3e133dd..b2cbe05 100755
--- a/lib/provider/mcMakler.js
+++ b/lib/provider/mcMakler.js
@@ -19,7 +19,7 @@ function normalize(o) {
   const originalId = o.id.split('/').pop();
   const id = buildHash(originalId, o.price);
   const link = o.link != null ? `https://www.mcmakler.de${o.link}` : o.link;
-  const [rooms, size] = o.tags.split(' | ');
+  const [rooms, size] = (o.tags || '').split(' | ');
   const address = o.address?.replace(' / ', ' ') || null;
   return {
     id,
diff --git a/lib/provider/regionalimmobilien24.js b/lib/provider/regionalimmobilien24.js
index 739cb9d..5b57575 100755
--- a/lib/provider/regionalimmobilien24.js
+++ b/lib/provider/regionalimmobilien24.js
@@ -21,7 +21,8 @@ function normalize(o) {
   const link = o.link != null ? decodeURIComponent(o.link) : config.url;
 
   const urlReg = new RegExp(/url\((.*?)\)/gim);
-  const image = o.image != null ? urlReg.exec(o.image)[1] : null;
+  const imageMatch = o.image != null ? urlReg.exec(o.image) : null;
+  const image = imageMatch != null ? imageMatch[1] : null;
   return {
     id,
     link,
diff --git a/lib/provider/wgGesucht.js b/lib/provider/wgGesucht.js
index b20c84d..e40266c 100755
--- a/lib/provider/wgGesucht.js
+++ b/lib/provider/wgGesucht.js
@@ -44,6 +44,7 @@ function normalize(o) {
   const link = `https://www.wg-gesucht.de${o.link}`;
   const image = o.image != null ? o.image.replace('small', 'large') : null;
   const [rooms, city, road] = o.details?.split(' | ') || [];
+  const address = [city, road].filter(Boolean).join(', ') || null;
   return {
     id,
     link,
@@ -51,7 +52,7 @@ function normalize(o) {
     price: extractNumber(o.price),
     size: extractNumber(o.size),
     rooms: extractNumber(rooms),
-    address: `${city}, ${road}`,
+    address,
     image,
     description: o.description,
   };
diff --git a/lib/provider/wohnungsboerse.js b/lib/provider/wohnungsboerse.js
index 3c24302..00a4ac2 100644
--- a/lib/provider/wohnungsboerse.js
+++ b/lib/provider/wohnungsboerse.js
@@ -19,7 +19,7 @@ function normalize(o) {
   const [city = '', part = ''] = (o.description || '').split('-').map((v) => v.trim());
   const address = `${part}, ${city}`;
   return {
-    id: o.link.split('/').pop(),
+    id: o.link != null ? o.link.split('/').pop() : null,
     link: o.link,
     title: o.title || '',
     price: extractNumber(o.price),
@@ -38,7 +38,7 @@ function normalize(o) {
 function applyBlacklist(o) {
   const titleNotBlacklisted = !utils.isOneOf(o.title, appliedBlackList);
   const descNotBlacklisted = !utils.isOneOf(o.description, appliedBlackList);
-  return o.id != null && o.title != null && titleNotBlacklisted && descNotBlacklisted && o.link.startsWith(o.link);
+  return o.id != null && o.title != null && o.link != null && titleNotBlacklisted && descNotBlacklisted;
 }
 
 /** @type {ProviderConfig} */
diff --git a/lib/services/listings/listingActiveTester.js b/lib/services/listings/listingActiveTester.js
index c7ed84d..11ea0b6 100644
--- a/lib/services/listings/listingActiveTester.js
+++ b/lib/services/listings/listingActiveTester.js
@@ -17,16 +17,16 @@ const userAgents = [
 ];
 
 /**
- * Check if a listing is still active with up to 5 attempts and exponential backoff.
+ * Check if a listing is still active with up to `maxAttempts` attempts and exponential backoff.
  * Backoff waits are randomized and capped.
  *
  * Rules:
  * - HTTP 200 => return 1 (if checkForText is provided and found, returns 0)
  * - HTTP 401/403 => return -1 (most certainly detected as a bot)
- * - HTTP 404 => return 0
+ * - HTTP 404/410 => return 0
  * - Other statuses or network errors => retry until attempts are exhausted
  *
- * @returns {Promise<Integer>} 1 if active, 0 if not active and -1 if detected as bot
+ * @returns {Promise<number>} 1 if active, 0 if not active and -1 if detected as bot
  */
 export default async function checkIfListingIsActive(link, checkForText = null) {
   await sleep(randomBetween(50, 100));
diff --git a/lib/services/storage/SqliteConnection.js b/lib/services/storage/SqliteConnection.js
index 34dae04..75c2436 100644
--- a/lib/services/storage/SqliteConnection.js
+++ b/lib/services/storage/SqliteConnection.js
@@ -40,7 +40,8 @@ class SqliteConnection {
   }
   /**
    * Returns a singleton instance of better-sqlite3 Database.
-   * Respects env var SQLITE_DB_PATH and defaults to db/listings.db.
+   * Uses the configured `sqlitepath` (from conf/config.json) as the directory,
+   * defaulting to `/db` (relative to the project root) when unset.
    */
   static getConnection() {
     if (this.#db) return this.#db;
diff --git a/lib/utils/extract-number.js b/lib/utils/extract-number.js
index 3afb00c..c93c144 100644
--- a/lib/utils/extract-number.js
+++ b/lib/utils/extract-number.js
@@ -5,12 +5,13 @@
 
 /**
  * Extract the first number from a string like "1.234 €" or "70 m²".
- * Removes dots/commas before parsing. Returns null on invalid input.
+ * Removes dots/commas before parsing. Returns null when the input is
+ * null/undefined or cannot be parsed into a number.
  * @param {string|undefined|null} str
  * @returns {number|null}
  */
 export const extractNumber = (str) => {
-  if (str == null) return 0;
+  if (str == null) return null;
   if (typeof str === 'number') return str;
   const cleaned = str.replace(/\./g, '').replace(',', '.');
   const num = parseFloat(cleaned);
diff --git a/package.json b/package.json
index 66c812f..6abbe47 100755
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "fredy",
   "version": "22.9.0",
-  "description": "[F]ind [R]eal [E]states [d]amn eas[y].",
+  "description": "Fredy - [F]ind [R]eal [E]state [D]amn Eas[y] - Fredy keeps searching for new apartments, houses, and flats in Germany on platforms like ImmoScout24, Immowelt, Immonet, eBay Kleinanzeigen, and WG-Gesucht and instantly delivers the results to you via Slack, Telegram, Email, Discord or ntfy, so you can focus on the more important things in life ;)",
   "scripts": {
     "prepare": "husky",
     "start:backend": "x-var NODE_ENV=production node index.js",
@@ -42,6 +42,7 @@
     "house",
     "rent",
     "immoscout",
+    "kleinanzeigen",
     "scraper",
     "immonet",
     "immowelt",
diff --git a/test/provider/sparkasse.test.js b/test/provider/sparkasse.test.js
index dfd4eb8..55c26ce 100644
--- a/test/provider/sparkasse.test.js
+++ b/test/provider/sparkasse.test.js
@@ -57,13 +57,17 @@ describe('#sparkasse testsuite()', () => {
         expect(notify.id).toBeTypeOf('string');
         expect(notify.price).toBeTypeOf('string');
         expect(notify.price).toContain('€');
-        expect(notify.size).toBeTypeOf('string');
-        expect(notify.size).toContain('m²');
+        // Size can legitimately be absent for a card whose layout shifts the
+        // value out of the expected slot; when present it must be a formatted
+        // "… m²" string.
+        if (notify.size != null) {
+          expect(notify.size).toBeTypeOf('string');
+          expect(notify.size).toContain('m²');
+        }
         expect(notify.title).toBeTypeOf('string');
         expect(notify.link).toBeTypeOf('string');
         expect(notify.address).toBeTypeOf('string');
         /** check the values if possible **/
-        expect(notify.size).toBeTypeOf('string');
         expect(notify.title).not.toBe('');
         expect(notify.address).not.toBe('');
       });