Fix non-ASCII token authentication crashes

atelier/app.py

@@ -199,7 +199,9 @@ def create_app(data_dir=None, provider_transport=None):
                 return JSONResponse({'detail': 'Fremde Herkunft nicht erlaubt.'}, status_code=403)
         if path == '/mcp' or path.startswith('/mcp/'):
             supplied = request.headers.get('authorization', '')
-            if not secrets.compare_digest(supplied, 'Bearer ' + mcp_token):
+            # ASGI headers are decoded as Latin-1; compare their original bytes.
+            # compare_digest(str, str) rejects non-ASCII characters.
+            if not secrets.compare_digest(supplied.encode('latin-1'), ('Bearer ' + mcp_token).encode('utf-8')):
                 return JSONResponse({'detail': 'MCP-Token erforderlich.'}, status_code=401)
         elif path.startswith('/api/') and path != '/api/login':
             session = request.cookies.get('atelier_session', '')
@@ -237,7 +239,7 @@ def create_app(data_dir=None, provider_transport=None):
         attempts[ip] = recent
         if len(recent) >= 10:
             raise HTTPException(429, 'Zu viele Versuche. Bitte eine Minute warten.')
-        if not secrets.compare_digest(body.token, admin_token):
+        if not secrets.compare_digest(body.token.encode('utf-8'), admin_token.encode('utf-8')):
             recent.append(stamp)
             raise HTTPException(401, 'Zugangsschlüssel stimmt nicht.')
         for key in list(sessions):

tests/test_app.py

@@ -181,3 +181,27 @@ def test_german_metadata_is_a_proposal_only(client):
     assert response.json()['title'] == 'Kundenanfrage höflich absagen'
     assert set(response.json()) == {'title','description','category','tags'}
     assert client.get('/api/prompts').json() == before
+
+
+@pytest.mark.parametrize('configured', ['ascii-test-token', 'synthetic-ü-token-🔐'])
+def test_mcp_non_ascii_tokens_never_crash(tmp_path, monkeypatch, configured):
+    monkeypatch.setenv('MCP_TOKEN', configured)
+    with TestClient(create_app(tmp_path)) as c:
+        initialize={'jsonrpc':'2.0','id':1,'method':'initialize','params':{'protocolVersion':'2025-03-26','capabilities':{},'clientInfo':{'name':'regression','version':'1'}}}
+        accept={'Accept':'application/json, text/event-stream'}
+        for path in ['/mcp', '/mcp/']:
+            for wrong in [b'', b'Bearer wrong', 'Bearer falsch-ä'.encode('utf-8'), b'Bearer \xff']:
+                assert c.post(path,headers={**accept,'Authorization':wrong},json=initialize).status_code == 401
+            headers={**accept,'Authorization':('Bearer '+configured).encode('utf-8')}
+            response=c.post(path,headers=headers,json=initialize)
+            assert response.status_code == 200
+            assert response.json()['result']['serverInfo']['name'] == 'CasaDePrompt'
+            listed=c.post(path,headers=headers,json={'jsonrpc':'2.0','id':2,'method':'tools/list','params':{}})
+            assert len(listed.json()['result']['tools']) == 4
+
+
+def test_web_login_with_unicode_token(tmp_path, monkeypatch):
+    monkeypatch.setenv('ADMIN_TOKEN', 'synthetic-ä-admin-🔐')
+    with TestClient(create_app(tmp_path)) as c:
+        assert c.post('/api/login',json={'token':'falsch-ü'}).status_code == 401
+        assert c.post('/api/login',json={'token':'synthetic-ä-admin-🔐'}).status_code == 200