diff --git a/ariadne/services/mailu_events.py b/ariadne/services/mailu_events.py
index d9aeb0b..86810fe 100644
--- a/ariadne/services/mailu_events.py
+++ b/ariadne/services/mailu_events.py
@@ -56,13 +56,7 @@ def _event_context(payload: dict[str, Any] | None) -> dict[str, Any]:
 class MailuEventRunner:
     """Debounce Keycloak events into Mailu synchronization runs."""
 
-    def __init__(
-        self,
-        min_interval_sec: float,
-        wait_timeout_sec: float,
-        runner: Callable[[str, bool], tuple[str, str]] | None = None,
-        thread_factory: Callable[..., threading.Thread] = threading.Thread,
-    ) -> None:
+    def __init__(self, min_interval_sec: float, wait_timeout_sec: float, runner: Callable[[str, bool], tuple[str, str]] | None = None, thread_factory: Callable[..., threading.Thread] = threading.Thread) -> None:
         self._min_interval_sec = min_interval_sec
         self._wait_timeout_sec = wait_timeout_sec
         self._runner = runner or self._default_runner
diff --git a/tests/test_mailu_events.py b/tests/test_mailu_events.py
index 9393052..94f9591 100644
--- a/tests/test_mailu_events.py
+++ b/tests/test_mailu_events.py
@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+from types import SimpleNamespace
+
+from ariadne.services import mailu_events as mailu_events_module
 from ariadne.services.mailu_events import MailuEventRunner
 
 
@@ -52,3 +55,95 @@ def test_mailu_event_debounce() -> None:
     status, payload = events.handle_event({"force": True})
     assert status == 202
     assert payload["status"] == "accepted"
+
+
+def test_mailu_event_parses_string_flags_and_context() -> None:
+    calls = []
+
+    def runner(reason: str, force: bool):
+        calls.append((reason, force))
+        return "ok", ""
+
+    events = MailuEventRunner(
+        min_interval_sec=0.0,
+        wait_timeout_sec=0.1,
+        runner=runner,
+        thread_factory=_instant_thread_factory,
+    )
+
+    status, payload = events.handle_event({"wait": "yes", "force": "on", "eventType": " UPDATE_PROFILE ", "userId": " u1 "})
+
+    assert status == 200
+    assert payload["status"] == "ok"
+    assert calls == [("keycloak_event:UPDATE_PROFILE", True)]
+
+
+def test_mailu_event_defaults_for_missing_payload() -> None:
+    calls = []
+
+    def runner(reason: str, force: bool):
+        calls.append((reason, force))
+        return "ok", ""
+
+    events = MailuEventRunner(
+        min_interval_sec=0.0,
+        wait_timeout_sec=0.1,
+        runner=runner,
+        thread_factory=_instant_thread_factory,
+    )
+
+    status, payload = events.handle_event(None)
+
+    assert status == 202
+    assert payload == {"status": "accepted", "triggered": True}
+    assert calls == [("keycloak_event", False)]
+
+
+def test_mailu_event_running_skip_and_wait_timeout() -> None:
+    def parked_thread_factory(target=None, args=(), daemon=None):
+        class ParkedThread:
+            def start(self) -> None:
+                return None
+
+        return ParkedThread()
+
+    events = MailuEventRunner(
+        min_interval_sec=0.0,
+        wait_timeout_sec=0.0,
+        runner=lambda _reason, _force: ("ok", ""),
+        thread_factory=parked_thread_factory,
+    )
+
+    status, payload = events.handle_event({"wait": True})
+    assert status == 200
+    assert payload == {"status": "running"}
+
+    status, payload = events.handle_event({})
+    assert status == 202
+    assert payload == {"status": "skipped", "triggered": False}
+
+
+def test_mailu_event_runner_reports_exceptions() -> None:
+    def failing_runner(_reason: str, _force: bool):
+        raise RuntimeError("mailu exploded")
+
+    events = MailuEventRunner(
+        min_interval_sec=0.0,
+        wait_timeout_sec=0.1,
+        runner=failing_runner,
+        thread_factory=_instant_thread_factory,
+    )
+
+    status, payload = events.handle_event({"wait": True})
+
+    assert status == 500
+    assert payload == {"status": "error", "detail": "mailu exploded"}
+
+
+def test_default_runner_maps_mailu_summary(monkeypatch) -> None:
+    events = MailuEventRunner(min_interval_sec=0.0, wait_timeout_sec=0.1)
+    monkeypatch.setattr(mailu_events_module.mailu, "sync", lambda reason, force=False: SimpleNamespace(failures=0, detail="synced"))
+    assert events._default_runner("test", True) == ("ok", "synced")
+
+    monkeypatch.setattr(mailu_events_module.mailu, "sync", lambda reason, force=False: SimpleNamespace(failures=1, detail="failed"))
+    assert events._default_runner("test", False) == ("error", "failed")