diff --git a/dev/test_multipart.py b/dev/test_multipart.py
new file mode 100644
index 0000000..e346b10
--- /dev/null
+++ b/dev/test_multipart.py
@@ -0,0 +1,234 @@
+#!/usr/bin/env python3
+"""Regressionstests für den Multipart-Parser im Router.
+
+Testet quoted/unquoted Boundaries, Open-WebUI-artige Requests,
+beliebige Feldreihenfolge und binäre Payloads.
+
+Aufruf: python3 dev/test_multipart.py
+"""
+import sys
+from email.parser import BytesParser
+from email.policy import compat32
+
+
+def parse_multipart(data: bytes, content_type: str) -> tuple[bytes, str, dict]:
+    """Identische Logik wie router/ai_profile_router.py::_parse_multipart."""
+    raw = (f"Content-Type: {content_type}\r\n\r\n").encode("utf-8") + data
+    msg = BytesParser(policy=compat32).parsebytes(raw)
+    if not msg.is_multipart():
+        raise ValueError("Kein multipart/form-data")
+    file_data = b""
+    filename = ""
+    fields = {}
+    for part in msg.get_payload():
+        disposition = part.get("Content-Disposition", "")
+        name = None
+        part_filename = None
+        for kv in disposition.split(";"):
+            kv = kv.strip()
+            if kv.startswith("name="):
+                name = kv[len("name="):].strip('"')
+            elif kv.startswith("filename="):
+                part_filename = kv[len("filename="):].strip('"')
+        if name is None:
+            continue
+        payload = part.get_payload(decode=True)
+        if payload is None:
+            payload = b""
+        if part_filename is not None:
+            file_data = payload
+            filename = part_filename or ""
+        else:
+            fields[name] = payload.decode("utf-8", errors="replace")
+    return file_data, filename, fields
+
+
+def build(body_parts: list[tuple[str, str | bytes, str | None]],
+          boundary: str, quoted: bool = False) -> tuple[bytes, str]:
+    """Baut einen Multipart-Body. body_parts: (name, value, filename)."""
+    b = f'"{boundary}"' if quoted else boundary
+    ct = f"multipart/form-data; boundary={b}"
+    parts = []
+    for name, value, filename in body_parts:
+        if isinstance(value, bytes):
+            header = (f'Content-Disposition: form-data; name="{name}"')
+            if filename:
+                header += f'; filename="{filename}"'
+            header += f'\r\nContent-Type: application/octet-stream\r\n\r\n'
+            parts.append(header.encode() + value + b"\r\n")
+        else:
+            parts.append(
+                f'Content-Disposition: form-data; name="{name}"\r\n\r\n{value}\r\n'
+                .encode()
+            )
+    sep = f"--{boundary}\r\n".encode()
+    body = sep + sep.join(parts) + (f"--{boundary}--\r\n").encode()
+    return body, ct
+
+
+def test_quoted_boundary():
+    """Quoted boundary (boundary=\"...\")."""
+    boundary = "----WebKitFormBoundary7MA4YWxkTrZu0gW"
+    webm = b"\x1a\x45\xdf\xa3" + b"\x00\x01\x02\x03\xff\xfe\xfd" * 50
+    body, ct = build(
+        [("model", "whisper-1", None), ("file", webm, "t.webm")],
+        boundary, quoted=True,
+    )
+    fd, fn, fl = parse_multipart(body, ct)
+    assert fd == webm, "file_data mismatch"
+    assert fn == "t.webm", f"filename mismatch: {fn!r}"
+    assert fl["model"] == "whisper-1", f"model mismatch: {fl!r}"
+    print("  quoted boundary: OK")
+
+
+def test_unquoted_boundary():
+    """Unquoted boundary (boundary=...)."""
+    boundary = "AaB03x"
+    body, ct = build(
+        [("file", b"RIFF", "a.wav"), ("language", "de", None)],
+        boundary, quoted=False,
+    )
+    fd, fn, fl = parse_multipart(body, ct)
+    assert fd == b"RIFF", "file_data mismatch"
+    assert fn == "a.wav", f"filename mismatch: {fn!r}"
+    assert fl["language"] == "de", f"language mismatch: {fl!r}"
+    print("  unquoted boundary: OK")
+
+
+def test_openwebui_style():
+    """Open-WebUI-artiger Request (quoted, extra Header, File vor model)."""
+    boundary = "----formdata-boundary"
+    webm = b"\x1a\x45\xdf\xa3" + b"\xde\xad\xbe\xef" * 30
+    ct = f'multipart/form-data; boundary="{boundary}"'
+    body = (
+        f"--{boundary}\r\n"
+        f'Content-Disposition: form-data; name="file"; filename="rec.webm"\r\n'
+        f"Content-Type: audio/webm; codecs=opus\r\n"
+        f"\r\n"
+    ).encode() + webm + (
+        f"\r\n--{boundary}\r\n"
+        f'Content-Disposition: form-data; name="model"\r\n'
+        f"\r\n"
+        f"whisper-1\r\n"
+        f"--{boundary}\r\n"
+        f'Content-Disposition: form-data; name="temperature"\r\n'
+        f"\r\n"
+        f"0.0\r\n"
+        f"--{boundary}--\r\n"
+    ).encode()
+    fd, fn, fl = parse_multipart(body, ct)
+    assert fd == webm, "file_data mismatch"
+    assert fn == "rec.webm", f"filename mismatch: {fn!r}"
+    assert fl["model"] == "whisper-1", f"model mismatch: {fl!r}"
+    assert fl["temperature"] == "0.0", f"temperature mismatch: {fl!r}"
+    print("  Open-WebUI-artig: OK")
+
+
+def test_file_before_model():
+    """File-Feld vor model-Feld."""
+    boundary = "boundary123"
+    body, ct = build(
+        [("file", b"DATA", "f.wav"), ("model", "whisper-1", None)],
+        boundary, quoted=False,
+    )
+    fd, fn, fl = parse_multipart(body, ct)
+    assert fd == b"DATA", "file_data mismatch"
+    assert fn == "f.wav", f"filename mismatch: {fn!r}"
+    assert fl["model"] == "whisper-1", f"model mismatch: {fl!r}"
+    print("  File vor model: OK")
+
+
+def test_file_after_model():
+    """model-Feld vor File-Feld."""
+    boundary = "boundary456"
+    body, ct = build(
+        [("model", "whisper-1", None), ("file", b"DATA", "g.wav")],
+        boundary, quoted=False,
+    )
+    fd, fn, fl = parse_multipart(body, ct)
+    assert fd == b"DATA", "file_data mismatch"
+    assert fn == "g.wav", f"filename mismatch: {fn!r}"
+    assert fl["model"] == "whisper-1", f"model mismatch: {fl!r}"
+    print("  File nach model: OK")
+
+
+def test_webm_binary_payload():
+    """WebM-Binärpayload (alle 256 Byte-Werte)."""
+    boundary = "boundary789"
+    webm = bytes(range(256)) * 10  # 2560 bytes
+    body, ct = build(
+        [("file", webm, "bin.webm")],
+        boundary, quoted=False,
+    )
+    fd, fn, fl = parse_multipart(body, ct)
+    assert fd == webm, f"file_data mismatch ({len(fd)} vs {len(webm)})"
+    assert fn == "bin.webm", f"filename mismatch: {fn!r}"
+    print("  WebM-Binärpayload: OK")
+
+
+def test_extra_headers_ignored():
+    """Zusätzliche Multipart-Header werden ignoriert."""
+    boundary = "boundaryExtra"
+    webm = b"\x1a\x45\xdf\xa3" + b"\x00" * 100
+    ct = f'multipart/form-data; boundary="{boundary}"'
+    body = (
+        f"--{boundary}\r\n"
+        f'Content-Disposition: form-data; name="file"; filename="x.webm"\r\n'
+        f"Content-Type: audio/webm\r\n"
+        f"X-Custom-Header: ignored\r\n"
+        f"Content-Transfer-Encoding: binary\r\n"
+        f"\r\n"
+    ).encode() + webm + (
+        f"\r\n--{boundary}\r\n"
+        f'Content-Disposition: form-data; name="model"\r\n'
+        f"\r\n"
+        f"whisper-1\r\n"
+        f"--{boundary}--\r\n"
+    ).encode()
+    fd, fn, fl = parse_multipart(body, ct)
+    assert fd == webm, "file_data mismatch"
+    assert fn == "x.webm", f"filename mismatch: {fn!r}"
+    assert fl["model"] == "whisper-1", f"model mismatch: {fl!r}"
+    print("  Extra-Header ignoriert: OK")
+
+
+def test_all_fields():
+    """Alle unterstützten Felder (model, language, prompt, response_format, temperature)."""
+    boundary = "boundaryAll"
+    body, ct = build(
+        [
+            ("file", b"AUDIO", "a.webm"),
+            ("model", "whisper-1", None),
+            ("language", "de", None),
+            ("prompt", "Kontext", None),
+            ("response_format", "verbose_json", None),
+            ("temperature", "0.5", None),
+        ],
+        boundary, quoted=True,
+    )
+    fd, fn, fl = parse_multipart(body, ct)
+    assert fd == b"AUDIO", "file_data mismatch"
+    assert fn == "a.webm", f"filename mismatch: {fn!r}"
+    assert fl["model"] == "whisper-1", f"model mismatch: {fl!r}"
+    assert fl["language"] == "de", f"language mismatch: {fl!r}"
+    assert fl["prompt"] == "Kontext", f"prompt mismatch: {fl!r}"
+    assert fl["response_format"] == "verbose_json", f"response_format mismatch: {fl!r}"
+    assert fl["temperature"] == "0.5", f"temperature mismatch: {fl!r}"
+    print("  Alle Felder: OK")
+
+
+def main():
+    print("Multipart-Parser Regressionstests:")
+    test_quoted_boundary()
+    test_unquoted_boundary()
+    test_openwebui_style()
+    test_file_before_model()
+    test_file_after_model()
+    test_webm_binary_payload()
+    test_extra_headers_ignored()
+    test_all_fields()
+    print("\nAlle Multipart-Parser-Tests bestanden!")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/router/ai_profile_router.py b/router/ai_profile_router.py
index 5b67122..b8fcc3f 100755
--- a/router/ai_profile_router.py
+++ b/router/ai_profile_router.py
@@ -45,6 +45,7 @@ Nur Python-Standardbibliothek. Logging nach stdout (journald).
 from __future__ import annotations
 
 import base64
+import email
 import json
 import logging
 import os
@@ -56,6 +57,8 @@ import threading
 import time
 import uuid
 import http.client
+from email.parser import BytesParser
+from email.policy import compat32
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 
 # ---------------------------------------------------------------------------
@@ -1127,42 +1130,47 @@ class Handler(BaseHTTPRequestHandler):
 
     def _parse_multipart(self, data: bytes, content_type: str
                          ) -> tuple[bytes, str, dict]:
-        """Parst multipart/form-data. Liefert (file_data, filename, fields)."""
-        boundary = None
-        for part in content_type.split(";"):
-            part = part.strip()
-            if part.startswith("boundary="):
-                boundary = part[len("boundary="):]
-                break
-        if not boundary:
-            raise ValueError("Kein Boundary in Content-Type")
+        """Parst multipart/form-data. Liefert (file_data, filename, fields).
+
+        Nutzt email.parser.BytesParser (Standardbibliothek) für robustes
+        MIME-Parsing. Handhabt quoted und unquoted Boundaries, beliebige
+        Feldreihenfolge, zusätzliche Header und binäre Payloads.
+        """
+        # MIME-Message aus rohen Bytes + Content-Type-Header bauen
+        raw = (f"Content-Type: {content_type}\r\n\r\n"
+               ).encode("utf-8") + data
+        msg = BytesParser(policy=compat32).parsebytes(raw)
+        if not msg.is_multipart():
+            raise ValueError("Kein multipart/form-data")
 
-        boundary_bytes = boundary.encode("utf-8")
         file_data = b""
         filename = ""
         fields = {}
 
-        parts = data.split(b"--" + boundary_bytes)
-        for part in parts:
-            if part in (b"", b"--", b"--\r\n", b"\r\n"):
+        for part in msg.get_payload():
+            disposition = part.get("Content-Disposition", "")
+            name = None
+            part_filename = None
+            for kv in disposition.split(";"):
+                kv = kv.strip()
+                if kv.startswith("name="):
+                    name = kv[len("name="):].strip('"')
+                elif kv.startswith("filename="):
+                    part_filename = kv[len("filename="):].strip('"')
+            if name is None:
                 continue
-            if b"\r\n\r\n" not in part:
-                continue
-            header_part, body_part = part.split(b"\r\n\r\n", 1)
-            if body_part.endswith(b"\r\n"):
-                body_part = body_part[:-2]
 
-            header_text = header_part.decode("utf-8", errors="replace")
-            for line in header_text.split("\r\n"):
-                if "name=" in line and "filename=" in line:
-                    for kv in line.split(";"):
-                        kv = kv.strip()
-                        if kv.startswith("filename="):
-                            filename = kv[len("filename="):].strip('"')
-                    file_data = body_part
-                elif "name=" in line:
-                    name = line.split("name=")[1].strip().strip('"')
-                    fields[name] = body_part.decode("utf-8", errors="replace")
+            payload = part.get_payload(decode=True)
+            if payload is None:
+                payload = b""
+
+            if part_filename is not None:
+                # Dateifeld (binär, nicht dekodieren)
+                file_data = payload
+                filename = part_filename or ""
+            else:
+                # Textfeld
+                fields[name] = payload.decode("utf-8", errors="replace")
 
         return file_data, filename, fields