diff --git a/homelab-ai-bot/savetv_web.py b/homelab-ai-bot/savetv_web.py
index ec65e19e..3121fc2e 100644
--- a/homelab-ai-bot/savetv_web.py
+++ b/homelab-ai-bot/savetv_web.py
@@ -43,9 +43,11 @@ def _save_download_log(log):
 
 DOWNLOAD_PROGRESS = Path("/mnt/savetv/.download_progress.json")
 DOWNLOAD_DIR = Path("/mnt/savetv")
+_PROGRESS_LOCK = threading.Lock()
 
 
-def _load_progress():
+def _load_progress_raw():
+    """Liest Progress-Datei ohne Lock (nur innerhalb von _PROGRESS_LOCK aufrufen)."""
     if DOWNLOAD_PROGRESS.exists():
         try:
             return json.loads(DOWNLOAD_PROGRESS.read_text())
@@ -54,11 +56,22 @@ def _load_progress():
     return {}
 
 
+def _save_progress_raw(prog):
+    """Schreibt Progress-Datei ohne Lock (nur innerhalb von _PROGRESS_LOCK aufrufen)."""
+    DOWNLOAD_PROGRESS.write_text(json.dumps(prog, ensure_ascii=False, indent=2))
+
+
+def _load_progress():
+    with _PROGRESS_LOCK:
+        return _load_progress_raw()
+
+
 def _save_progress(prog):
-    try:
-        DOWNLOAD_PROGRESS.write_text(json.dumps(prog, ensure_ascii=False, indent=2))
-    except Exception:
-        pass
+    with _PROGRESS_LOCK:
+        try:
+            _save_progress_raw(prog)
+        except Exception:
+            pass
 
 
 def _head_content_length(url):
@@ -722,12 +735,14 @@ def api_download():
         filename = f"{safe_title}_{tid}.mp4"
         target = DOWNLOAD_DIR / filename
 
-        progress[str(tid)] = {
-            "filename": filename,
-            "expected_bytes": expected_bytes,
-            "started_at": datetime.now().isoformat(),
-        }
-        _save_progress(progress)
+        with _PROGRESS_LOCK:
+            cur_progress = _load_progress_raw()
+            cur_progress[str(tid)] = {
+                "filename": filename,
+                "expected_bytes": expected_bytes,
+                "started_at": datetime.now().isoformat(),
+            }
+            _save_progress_raw(cur_progress)
 
         DOWNLOAD_DIR.mkdir(parents=True, exist_ok=True)
         try:
@@ -735,10 +750,13 @@ def api_download():
                 ["wget", "-q", "-O", str(target), url],
                 stdout=subprocess.DEVNULL,
                 stderr=subprocess.DEVNULL,
+                start_new_session=True,
             )
         except Exception as e:
-            progress.pop(str(tid), None)
-            _save_progress(progress)
+            with _PROGRESS_LOCK:
+                cur_progress = _load_progress_raw()
+                cur_progress.pop(str(tid), None)
+                _save_progress_raw(cur_progress)
             return {"tid": tid, "ok": False, "error": f"wget: {e}"}
 
         dl_log[str(tid)] = "running"