Preserve microseconds in datetime filter formatting

Include fractional seconds (.%f) when datetime.microsecond is non-zero
to avoid silently truncating high-precision timestamps. Added test.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: tpellissier

src/PowerPlatform/Dataverse/models/filters.py

@@ -91,6 +91,8 @@ def _format_value(value: Any) -> str:
         # Convert timezone-aware datetimes to UTC; assume naive datetimes are UTC
         if value.tzinfo is not None:
             value = value.astimezone(timezone.utc)
+        if value.microsecond:
+            return value.strftime("%Y-%m-%dT%H:%M:%S.%fZ")
         return value.strftime("%Y-%m-%dT%H:%M:%SZ")
     if isinstance(value, date):
         return value.strftime("%Y-%m-%d")

tests/unit/models/test_filters.py

@@ -98,6 +98,11 @@ def test_datetime_utc(self):
         dt = datetime(2024, 1, 15, 10, 30, 0, tzinfo=timezone.utc)
         self.assertEqual(_format_value(dt), "2024-01-15T10:30:00Z")
 
+    def test_datetime_with_microseconds(self):
+        """Microseconds should be preserved when non-zero."""
+        dt = datetime(2024, 1, 15, 10, 30, 0, 123456)
+        self.assertEqual(_format_value(dt), "2024-01-15T10:30:00.123456Z")
+
     def test_datetime_non_utc_converted(self):
         """Timezone-aware non-UTC datetimes should be converted to UTC."""
         eastern = timezone(timedelta(hours=-5))