Preserve sub-hour precision for LookML 'time' timeframe

sidemantic/adapters/lookml.py

@@ -736,7 +736,9 @@ def _parse_dimension_group(
     # Timeframes that truncate a timestamp to a coarser time grain. These keep
     # type="time" with a Sidemantic granularity so they behave as time dimensions.
     _TIME_GRANULARITY_TIMEFRAMES = {
-        "time": "hour",
+        # Looker's "time" timeframe keeps full timestamp precision (to the second);
+        # truncating to the hour silently collapses sub-hour rows.
+        "time": "second",
         "time_of_day": "hour",
         "hour": "hour",
         "minute": "minute",
@@ -1852,7 +1854,7 @@ def _export_view(self, model: Model, graph: SemanticGraph) -> dict:
             for dim in time_dims:
                 # Extract base name (remove _date, _week, etc suffix)
                 base_name = dim.name
-                for suffix in ["_date", "_week", "_month", "_quarter", "_year", "_time", "_hour"]:
+                for suffix in ["_date", "_week", "_month", "_quarter", "_year", "_time", "_hour", "_minute", "_second"]:
                     if dim.name.endswith(suffix):
                         base_name = dim.name[: -len(suffix)]
                         break
@@ -1862,7 +1864,9 @@ def _export_view(self, model: Model, graph: SemanticGraph) -> dict:
             for base_name, dims in base_name_groups.items():
                 # Map granularity to timeframe
                 granularity_mapping = {
-                    "hour": "time",
+                    "second": "time",
+                    "minute": "minute",
+                    "hour": "hour",
                     "day": "date",
                     "week": "week",
                     "month": "month",

tests/adapters/lookml/test_advanced_measure_types.py

@@ -129,7 +129,7 @@ class TestDimensionGroupTimeframes:
     def test_time_truncation_timeframes_are_time(self, graph):
         model = graph.get_model("events_calendar")
         for tf, gran in [
-            ("occurred_time", "hour"),
+            ("occurred_time", "second"),
             ("occurred_date", "day"),
             ("occurred_week", "week"),
             ("occurred_month", "month"),

tests/adapters/lookml/test_edge_cases.py

@@ -2212,6 +2212,57 @@ def test_lookml_view_with_unsupported_derived_table_not_defaulted():
     assert model.table is None  # not fabricated as a physical table named after the view
 
 
+def test_lookml_time_timeframe_keeps_second_precision():
+    """Looker's "time" timeframe keeps to-the-second precision, not hour."""
+    graph = _parse_lkml(
+        """
+view: v {
+  sql_table_name: t ;;
+  dimension: id { primary_key: yes  type: number  sql: ${TABLE}.id ;; }
+  dimension_group: created {
+    type: time
+    timeframes: [time, date, minute]
+    sql: ${TABLE}.created_at ;;
+  }
+}
+"""
+    )
+    model = graph.get_model("v")
+    assert model.get_dimension("created_time").granularity == "second"
+    assert model.get_dimension("created_minute").granularity == "minute"
+    assert model.get_dimension("created_date").granularity == "day"
+
+
+def test_lookml_time_grain_roundtrip():
+    """time/hour/minute/date grains round-trip through export without grain or suffix corruption."""
+    import tempfile
+
+    graph = _parse_lkml(
+        """
+view: v {
+  sql_table_name: t ;;
+  dimension: id { primary_key: yes  type: number  sql: ${TABLE}.id ;; }
+  dimension_group: created {
+    type: time
+    timeframes: [time, hour, minute, date]
+    sql: ${TABLE}.created_at ;;
+  }
+}
+"""
+    )
+    out = tempfile.mktemp(suffix=".lkml")
+    LookMLAdapter().export(graph, out)
+    grains = {
+        d.name: d.granularity for d in LookMLAdapter().parse(Path(out)).get_model("v").dimensions if d.type == "time"
+    }
+    assert grains == {
+        "created_time": "second",
+        "created_hour": "hour",
+        "created_minute": "minute",
+        "created_date": "day",
+    }
+
+
 def test_lookml_view_without_table_defaults_to_view_name():
     """A view with no sql_table_name/derived_table should default its table to the view name."""
     from sidemantic import SemanticLayer

tests/adapters/lookml/test_fixtures.py

@@ -69,7 +69,7 @@ def test_redshift_etl_errors_time_dimensions(self):
         model = self.graph.get_model("redshift_etl_errors")
         assert model.get_dimension("error_time") is not None
         assert model.get_dimension("error_time").type == "time"
-        assert model.get_dimension("error_time").granularity == "hour"
+        assert model.get_dimension("error_time").granularity == "second"
         assert model.get_dimension("error_date") is not None
         assert model.get_dimension("error_date").type == "time"
         assert model.get_dimension("error_date").granularity == "day"
@@ -332,7 +332,7 @@ def test_created_time_group(self):
         assert model.get_dimension("created_month") is not None
         assert model.get_dimension("created_year") is not None
         assert model.get_dimension("created_time") is not None
-        assert model.get_dimension("created_time").granularity == "hour"
+        assert model.get_dimension("created_time").granularity == "second"
 
     def test_shipped_time_group(self):
         model = self.graph.get_model("order_items")

tests/adapters/lookml/test_parsing.py

@@ -119,7 +119,8 @@ def test_lookml_adapter_ecommerce():
     # Test dimension group with multiple timeframes
     created_time = orders.get_dimension("created_time")
     assert created_time is not None
-    assert created_time.granularity == "hour"
+    # Looker's "time" timeframe keeps to-the-second precision.
+    assert created_time.granularity == "second"
 
     created_date = orders.get_dimension("created_date")
     assert created_date is not None