diff --git a/Dockerfile b/Dockerfile
index a217944..1ed67e4 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,44 +1,20 @@
 FROM python:3.12-slim
 
-ARG SUPERCRONIC_VERSION=v0.2.48
-ARG SUPERCRONIC_URL=https://github.com/aptible/supercronic/releases/download/${SUPERCRONIC_VERSION}/supercronic-linux-amd64
-ARG SUPERCRONIC_SHA1SUM=016b7c9aebfc8d9fd9526e8ba33b191fc524485f
-
-RUN apt-get update \
-    && apt-get install -y --no-install-recommends curl ca-certificates \
-    && curl -fsSLO "$SUPERCRONIC_URL" \
-    && echo "${SUPERCRONIC_SHA1SUM}  supercronic-linux-amd64" | sha1sum -c - \
-    && chmod +x supercronic-linux-amd64 \
-    && mv supercronic-linux-amd64 /usr/local/bin/supercronic \
-    && apt-get purge -y curl \
-    && apt-get autoremove -y \
-    && rm -rf /var/lib/apt/lists/*
-
 WORKDIR /app
 
 COPY requirements.txt /app/requirements.txt
 RUN pip install --no-cache-dir -r /app/requirements.txt
 
-# Enthält sowohl den Sync/Mailer-Code als auch die api/-App.
-# Welcher Teil tatsächlich läuft, entscheidet der Command in docker-compose.yml,
-# nicht das Image selbst -- ein Image, drei mögliche Rollen (sync, mailer, api).
 COPY src/ /app/
-COPY docker/run-sync.sh /usr/local/bin/run-sync.sh
-COPY docker/run-mailer.sh /usr/local/bin/run-mailer.sh
 COPY docker/entrypoint.sh /usr/local/bin/entrypoint.sh
-COPY docker/crontab.default /etc/crontabs/app-crontab
-
-RUN chmod +x /usr/local/bin/run-sync.sh /usr/local/bin/run-mailer.sh /usr/local/bin/entrypoint.sh
+RUN chmod +x /usr/local/bin/entrypoint.sh
 
 RUN mkdir -p /app/config \
     && useradd -m -u 10001 syncuser \
-    && chown -R syncuser:syncuser /app /etc/crontabs
+    && chown -R syncuser:syncuser /app
 USER syncuser
 
 HEALTHCHECK --interval=5m --timeout=10s --start-period=30s \
     CMD test -f /tmp/last_sync_ok || exit 1
 
-# Default-Entrypoint startet den Sync+Mailer-Cron-Modus.
-# Der Web/API-Service in docker-compose.yml überschreibt "command" komplett
-# mit uvicorn und läuft damit im selben Image in einer anderen Rolle.
 ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]
diff --git a/docker/crontab.default b/docker/crontab.default
deleted file mode 100644
index 8fbfeb0..0000000
--- a/docker/crontab.default
+++ /dev/null
@@ -1,2 +0,0 @@
-*/15 * * * * /usr/local/bin/run-sync.sh >> /proc/1/fd/1 2>> /proc/1/fd/2
-0 7 * * * /usr/local/bin/run-mailer.sh >> /proc/1/fd/1 2>> /proc/1/fd/2
diff --git a/docker/entrypoint.sh b/docker/entrypoint.sh
index c44f3f7..d42e403 100644
--- a/docker/entrypoint.sh
+++ b/docker/entrypoint.sh
@@ -7,18 +7,7 @@ if [ $# -gt 0 ]; then
     exec "$@"
 fi
 
-MAIL_HOUR="${MAIL_SEND_HOUR:-7}"
-
 echo "Starte icloud-contacts-sync Container"
-echo "Sync-Schedule: */15 * * * * (alle 15 Minuten, Delta-Sync)"
-echo "Mailer-Schedule: taeglich um ${MAIL_HOUR} Uhr (falls MAILER_ENABLED=true)"
+echo "Scheduler: Python-basiert (kein supercronic)"
 
-# Crontab wird zur Laufzeit generiert, damit MAIL_SEND_HOUR konfigurierbar bleibt.
-cat > /etc/crontabs/app-crontab <<EOF
-*/15 * * * * /usr/local/bin/run-sync.sh >> /proc/1/fd/1 2>> /proc/1/fd/2
-0 ${MAIL_HOUR} * * * /usr/local/bin/run-mailer.sh >> /proc/1/fd/1 2>> /proc/1/fd/2
-EOF
-
-/usr/local/bin/run-sync.sh || echo "Initialer Sync fehlgeschlagen, Cron laeuft trotzdem weiter"
-
-exec supercronic -json /etc/crontabs/app-crontab
+exec python3 /app/scheduler.py
diff --git a/docker/run-mailer.sh b/docker/run-mailer.sh
deleted file mode 100644
index 289b67c..0000000
--- a/docker/run-mailer.sh
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/bin/sh
-set -e
-cd /app
-echo "$(date -Is) - Mailer-Lauf gestartet"
-python3 /app/mailer.py
-echo "$(date -Is) - Mailer-Lauf beendet"
diff --git a/docker/run-sync.sh b/docker/run-sync.sh
deleted file mode 100644
index 975ab47..0000000
--- a/docker/run-sync.sh
+++ /dev/null
@@ -1,7 +0,0 @@
-#!/bin/sh
-set -e
-cd /app
-echo "$(date -Is) - Sync-Lauf gestartet"
-python3 /app/sync.py
-echo "$(date -Is) - Sync-Lauf beendet"
-touch /tmp/last_sync_ok
diff --git a/src/scheduler.py b/src/scheduler.py
new file mode 100644
index 0000000..7c9b4cd
--- /dev/null
+++ b/src/scheduler.py
@@ -0,0 +1,116 @@
+#!/usr/bin/env python3
+"""Einfacher Cron-Scheduler fuer Sync und Mailer.
+Ersetzt supercronic komplett — keine externe Abhaengigkeit noetig.
+
+Laeuft als PID 1 im Docker-Container und plant:
+  - Sync:  alle 15 Minuten (Delta-Sync)
+  - Mailer: taeglich um MAIL_SEND_HOUR Uhr (falls MAILER_ENABLED=true)
+
+Der Scheduler faengt SIGTERM/SIGINT ab und beendet sich sauber,
+damit Docker den Container korrekt stoppen kann."""
+import logging
+import os
+import signal
+import subprocess
+import sys
+import time
+from datetime import datetime, timedelta
+
+logging.basicConfig(
+    level=os.environ.get("LOG_LEVEL", "INFO"),
+    format="%(asctime)s [%(levelname)s] %(message)s",
+)
+logger = logging.getLogger("scheduler")
+
+SYNC_INTERVAL_MINUTES = 15
+MAIL_SEND_HOUR = int(os.environ.get("MAIL_SEND_HOUR", "7"))
+MAILER_ENABLED = os.environ.get("MAILER_ENABLED", "false").lower() == "true"
+
+_shutdown = False
+
+
+def _handle_signal(signum, _frame):
+    global _shutdown
+    signame = signal.Signals(signum).name
+    logger.info("Signal %s empfangen, Scheduler faehrt herunter...", signame)
+    _shutdown = True
+
+
+def run_script(name: str, script_path: str):
+    logger.info("--- %s-Lauf gestartet ---", name)
+    try:
+        result = subprocess.run(
+            [sys.executable, script_path],
+            cwd="/app",
+            timeout=300,
+        )
+        if result.returncode == 0:
+            logger.info("%s-Lauf erfolgreich beendet", name)
+        else:
+            logger.error("%s-Lauf fehlgeschlagen (exit code %d)", name, result.returncode)
+    except subprocess.TimeoutExpired:
+        logger.error("%s-Lauf hat 5 Minuten ueberschritten, abgebrochen", name)
+    except Exception:
+        logger.exception("Unerwarteter Fehler waehrend %s-Lauf", name)
+
+
+def run_sync():
+    run_script("Sync", "/app/sync.py")
+    try:
+        with open("/tmp/last_sync_ok", "w") as f:
+            f.write(datetime.now().isoformat())
+    except OSError:
+        pass
+
+
+def run_mailer():
+    if not MAILER_ENABLED:
+        return
+    run_script("Mailer", "/app/mailer.py")
+
+
+def next_run_time(hour: int) -> datetime:
+    now = datetime.now()
+    target = now.replace(hour=hour, minute=0, second=0, microsecond=0)
+    if target <= now:
+        target += timedelta(days=1)
+    return target
+
+
+def main():
+    global _shutdown
+
+    signal.signal(signal.SIGTERM, _handle_signal)
+    signal.signal(signal.SIGINT, _handle_signal)
+
+    logger.info("Scheduler gestartet")
+    logger.info("Sync: alle %d Minuten", SYNC_INTERVAL_MINUTES)
+    if MAILER_ENABLED:
+        logger.info("Mailer: taeglich um %d:00 Uhr", MAIL_SEND_HOUR)
+    else:
+        logger.info("Mailer: deaktiviert (MAILER_ENABLED=false)")
+
+    logger.info("Fuehre initialen Sync aus...")
+    run_sync()
+
+    last_sync = datetime.now()
+    next_mailer = next_run_time(MAIL_SEND_HOUR)
+
+    while not _shutdown:
+        now = datetime.now()
+
+        if now >= last_sync + timedelta(minutes=SYNC_INTERVAL_MINUTES):
+            run_sync()
+            last_sync = now
+
+        if MAILER_ENABLED and now >= next_mailer:
+            run_mailer()
+            next_mailer = next_run_time(MAIL_SEND_HOUR)
+
+        time.sleep(10)
+
+    logger.info("Scheduler beendet")
+
+
+if __name__ == "__main__":
+    main()