fix(observability): explicitly initialize LifecycleDispatcher guard attributes for mypyc compatibility (#254)

Fixes `AttributeError: 'LifecycleDispatcher' object has no attribute 'has_pool_create'` exception raised on some drivers after the telemetry integration was released.

Author: cofin

sqlspec/observability/_dispatcher.py

@@ -37,9 +37,31 @@
 class LifecycleDispatcher:
     """Dispatches lifecycle hooks with guard flags and diagnostics counters."""
 
-    __slots__ = ("_hooks", "_counters", *GUARD_ATTRS)
+    __slots__ = (
+        "_counters",
+        "_hooks",
+        "has_connection_create",
+        "has_connection_destroy",
+        "has_error",
+        "has_pool_create",
+        "has_pool_destroy",
+        "has_query_complete",
+        "has_query_start",
+        "has_session_end",
+        "has_session_start",
+    )
 
     def __init__(self, hooks: "dict[str, Iterable[Any]] | None" = None) -> None:
+        self.has_pool_create = False
+        self.has_pool_destroy = False
+        self.has_connection_create = False
+        self.has_connection_destroy = False
+        self.has_session_start = False
+        self.has_session_end = False
+        self.has_query_start = False
+        self.has_query_complete = False
+        self.has_error = False
+
         normalized: dict[LifecycleEvent, tuple[Any, ...]] = {}
         for event_name, guard_attr in zip(EVENT_ATTRS, GUARD_ATTRS, strict=False):
             callables = hooks.get(event_name) if hooks else None

tests/unit/test_observability.py

@@ -216,6 +216,25 @@ def observer(_event: Any) -> None:
     assert observer_called == []  # observers run via runtime, dispatcher unaffected
 
 
+def test_lifecycle_dispatcher_guard_attributes_always_accessible() -> None:
+    """All guard attributes should be accessible even with no hooks (mypyc compatibility)."""
+
+    dispatcher = LifecycleDispatcher(None)
+    assert dispatcher.has_pool_create is False
+    assert dispatcher.has_pool_destroy is False
+    assert dispatcher.has_connection_create is False
+    assert dispatcher.has_connection_destroy is False
+    assert dispatcher.has_session_start is False
+    assert dispatcher.has_session_end is False
+    assert dispatcher.has_query_start is False
+    assert dispatcher.has_query_complete is False
+    assert dispatcher.has_error is False
+
+    dispatcher_with_hooks = LifecycleDispatcher(cast("dict[str, Iterable[Any]]", {"on_query_start": [lambda ctx: ctx]}))
+    assert dispatcher_with_hooks.has_query_start is True
+    assert dispatcher_with_hooks.has_pool_create is False
+
+
 def test_lifecycle_dispatcher_counts_events() -> None:
     """Lifecycle dispatcher should count emitted events for diagnostics."""