diff --git a/common.py b/common.py
index 13369ae..063bc66 100644
--- a/common.py
+++ b/common.py
@@ -23,7 +23,7 @@ from starlette.middleware.base import BaseHTTPMiddleware
 BASE_DIR = os.path.dirname(__file__)
 TOKENS_FILE = os.path.join(BASE_DIR, "tokens.json")
 CONFIG_FILE = os.path.join(BASE_DIR, "config.json")
-VALID_USERS = ["stefan", "kati"]
+VALID_USERS = ["stefan", "kati", "test"]
 
 _config_cache = None
 
@@ -61,8 +61,11 @@ def _load_tokens():
     return _tokens_cache
 
 
+USER_ALIASES = {"test": "stefan"}
+
 def get_current_user() -> str | None:
-    return _current_user.get()
+    user = _current_user.get()
+    return USER_ALIASES.get(user, user)
 
 
 def get_user_key(username: str) -> str:
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
new file mode 100755
index 0000000..c30198a
--- /dev/null
+++ b/tests/run_tests.sh
@@ -0,0 +1,26 @@
+#!/bin/bash
+# MCP Server Integration Tests — laeuft taeglich via systemd timer
+set -uo pipefail
+
+LOG="/var/log/mcp-tests.log"
+NTFY_TOPIC="admin"
+VENV="/opt/mcp-servers/venv/bin"
+
+echo "[$(date)] MCP Tests gestartet" | tee -a "$LOG"
+
+OUTPUT=$($VENV/python -m pytest /opt/mcp-servers/tests/test_all.py -v --tb=short 2>&1)
+EXIT=$?
+
+echo "$OUTPUT" | tee -a "$LOG"
+
+if [ $EXIT -eq 0 ]; then
+    PASSED=$(echo "$OUTPUT" | grep -oP '\d+ passed' | head -1)
+    echo "[$(date)] MCP Tests OK: $PASSED" | tee -a "$LOG"
+else
+    FAILED=$(echo "$OUTPUT" | grep "FAILED" | head -5)
+    echo "[$(date)] MCP Tests FEHLGESCHLAGEN" | tee -a "$LOG"
+    /usr/local/bin/notify-ntfy "$NTFY_TOPIC" "MCP Tests fehlgeschlagen" \
+        "$(echo "$FAILED" | head -3)\n\nLog: tail -50 $LOG" "urgent" "x,test_tube"
+fi
+
+exit $EXIT
diff --git a/tests/test_all.py b/tests/test_all.py
new file mode 100644
index 0000000..27d1214
--- /dev/null
+++ b/tests/test_all.py
@@ -0,0 +1,226 @@
+#!/usr/bin/env python3
+"""MCP Server Integration Tests.
+
+Tests all tools on all servers via HTTP, using the 'test' OAuth client.
+Run: /opt/mcp-servers/venv/bin/python -m pytest /opt/mcp-servers/tests/test_all.py -v
+"""
+
+import json
+import hashlib
+import base64
+import secrets
+
+import httpx
+import pytest
+
+SERVERS = {
+    "mail": 5100,
+    "calendar": 5101,
+    "contacts": 5102,
+    "files": 5103,
+    "notes": 5104,
+}
+
+with open("/opt/mcp-servers/tokens.json") as f:
+    TEST_SECRET = json.load(f)["test"]["token"]
+
+
+def get_token(port):
+    """Get access token via OAuth client_credentials."""
+    r = httpx.post(f"http://127.0.0.1:{port}/token", data={
+        "grant_type": "client_credentials",
+        "client_id": "test",
+        "client_secret": TEST_SECRET,
+    }, timeout=10)
+    assert r.status_code == 200, f"Token request failed: {r.text}"
+    return r.json()["access_token"]
+
+
+def get_token_pkce(port):
+    """Get access token via OAuth authorization_code + PKCE."""
+    verifier = secrets.token_urlsafe(32)
+    challenge = base64.urlsafe_b64encode(
+        hashlib.sha256(verifier.encode()).digest()
+    ).rstrip(b"=").decode()
+
+    r = httpx.get(f"http://127.0.0.1:{port}/authorize", params={
+        "response_type": "code",
+        "client_id": "test",
+        "redirect_uri": "http://localhost/callback",
+        "code_challenge": challenge,
+        "code_challenge_method": "S256",
+    }, follow_redirects=False, timeout=10)
+    assert r.status_code == 302
+    code = r.headers["location"].split("code=")[1].split("&")[0]
+
+    r2 = httpx.post(f"http://127.0.0.1:{port}/token", data={
+        "grant_type": "authorization_code",
+        "code": code,
+        "client_id": "test",
+        "code_verifier": verifier,
+    }, timeout=10)
+    assert r2.status_code == 200, f"Token exchange failed: {r2.text}"
+    return r2.json()["access_token"]
+
+
+def mcp_call(port, token, method, params=None):
+    """Call an MCP method and return the result."""
+    r = httpx.post(f"http://127.0.0.1:{port}/mcp",
+        json={"jsonrpc": "2.0", "id": 1, "method": method, "params": params or {}},
+        headers={
+            "Authorization": f"Bearer {token}",
+            "Accept": "application/json, text/event-stream",
+        }, timeout=30)
+    assert r.status_code == 200, f"MCP request failed: {r.status_code} {r.text[:200]}"
+    for line in r.text.split("\n"):
+        if line.startswith("data: "):
+            return json.loads(line[6:])
+    return None
+
+
+def tool_call(port, token, tool_name, arguments=None):
+    """Call an MCP tool and return the text content."""
+    result = mcp_call(port, token, "tools/call", {
+        "name": tool_name,
+        "arguments": arguments or {},
+    })
+    assert result is not None, "No SSE response"
+    assert "error" not in result, f"RPC error: {result.get('error')}"
+    content = result["result"]["content"]
+    assert len(content) > 0, "Empty content"
+    return content[0].get("text", "")
+
+
+# --- OAuth Tests ---
+
+class TestOAuth:
+    @pytest.mark.parametrize("service,port", SERVERS.items())
+    def test_metadata(self, service, port):
+        r = httpx.get(f"http://127.0.0.1:{port}/.well-known/oauth-authorization-server", timeout=10)
+        assert r.status_code == 200
+        d = r.json()
+        assert "authorization_endpoint" in d
+        assert "token_endpoint" in d
+
+    @pytest.mark.parametrize("service,port", SERVERS.items())
+    def test_client_credentials(self, service, port):
+        token = get_token(port)
+        assert len(token) > 20
+
+    @pytest.mark.parametrize("service,port", SERVERS.items())
+    def test_pkce_flow(self, service, port):
+        token = get_token_pkce(port)
+        assert len(token) > 20
+
+    @pytest.mark.parametrize("service,port", SERVERS.items())
+    def test_invalid_secret(self, service, port):
+        r = httpx.post(f"http://127.0.0.1:{port}/token", data={
+            "grant_type": "client_credentials",
+            "client_id": "test",
+            "client_secret": "WRONG",
+        }, timeout=10)
+        assert r.status_code == 401
+
+    @pytest.mark.parametrize("service,port", SERVERS.items())
+    def test_no_auth(self, service, port):
+        r = httpx.post(f"http://127.0.0.1:{port}/mcp",
+            json={"jsonrpc": "2.0", "id": 1, "method": "tools/list", "params": {}},
+            headers={"Accept": "application/json, text/event-stream"},
+            timeout=10)
+        assert r.status_code == 401
+
+
+# --- Mail Tests ---
+
+class TestMail:
+    @pytest.fixture(autouse=True)
+    def setup(self):
+        self.token = get_token(SERVERS["mail"])
+
+    def test_list_accounts(self):
+        text = tool_call(SERVERS["mail"], self.token, "list_accounts")
+        assert "d370128_0-slohmaier" in text
+        assert "folders" in text
+
+    def test_list_folders(self):
+        text = tool_call(SERVERS["mail"], self.token, "list_folders", {"account": "d370128_0-slohmaier"})
+        assert "INBOX" in text
+
+    def test_search_mail(self):
+        text = tool_call(SERVERS["mail"], self.token, "search_mail", {"query": "stefan", "limit": 2})
+        assert "Subject:" in text or "No results" in text
+
+    def test_search_nonexistent(self):
+        text = tool_call(SERVERS["mail"], self.token, "search_mail", {"query": "xyzzy_nonexistent_12345", "limit": 1, "account": "d370128_0-gitea"})
+        assert "No results" in text
+
+
+# --- Calendar Tests ---
+
+class TestCalendar:
+    @pytest.fixture(autouse=True)
+    def setup(self):
+        self.token = get_token(SERVERS["calendar"])
+
+    def test_list_calendars(self):
+        text = tool_call(SERVERS["calendar"], self.token, "list_calendars")
+        assert "calendar-stefan" in text or "Stefan" in text
+
+    def test_list_task_lists(self):
+        text = tool_call(SERVERS["calendar"], self.token, "list_task_lists")
+        assert "reminders" in text.lower() or "erinnerungen" in text.lower() or "calendar" in text.lower()
+
+    def test_get_events(self):
+        text = tool_call(SERVERS["calendar"], self.token, "get_events", {
+            "calendar": "stefan", "date_from": "2026-06-01", "date_to": "2026-06-30"
+        })
+        assert "Wann:" in text or "Keine Termine" in text
+
+    def test_search_events(self):
+        text = tool_call(SERVERS["calendar"], self.token, "search_events", {"query": "Training"})
+        assert "UID:" in text or "Keine Treffer" in text
+
+
+# --- Contacts Tests ---
+
+class TestContacts:
+    @pytest.fixture(autouse=True)
+    def setup(self):
+        self.token = get_token(SERVERS["contacts"])
+
+    def test_search_contacts(self):
+        text = tool_call(SERVERS["contacts"], self.token, "search_contacts", {"query": "Lohmaier", "limit": 3})
+        assert "Lohmaier" in text or "Keine Kontakte" in text
+
+    def test_search_empty(self):
+        text = tool_call(SERVERS["contacts"], self.token, "search_contacts", {"query": "xyzzy_nonexistent_99999"})
+        assert "Keine Kontakte" in text
+
+
+# --- Files Tests ---
+
+class TestFiles:
+    @pytest.fixture(autouse=True)
+    def setup(self):
+        self.token = get_token(SERVERS["files"])
+
+    def test_list_root(self):
+        text = tool_call(SERVERS["files"], self.token, "list_files", {"path": "/"})
+        assert "DIR" in text or "Empty" in text or "Leeres" in text
+
+    def test_file_info(self):
+        text = tool_call(SERVERS["files"], self.token, "file_info", {"path": "/"})
+        assert "Verzeichnis" in text or "Directory" in text or "Name:" in text
+
+
+# --- Notes Tests ---
+
+class TestNotes:
+    @pytest.fixture(autouse=True)
+    def setup(self):
+        self.token = get_token(SERVERS["notes"])
+
+    def test_list_notebooks(self):
+        text = tool_call(SERVERS["notes"], self.token, "list_notebooks")
+        # Notes likely not configured, so accept error message too
+        assert "Kein" in text or "Fehler" in text or "id:" in text.lower()