Support inexact conference dates

Closes: #188

tests/test_add_new_conference.py

@@ -47,6 +47,33 @@ def test_insert_sorted_allows_same_url_different_year_without_year_component() -
     assert updated[1]["name"] == "NewConf"
 
 
+def test_insert_sorted_supports_nested_dates() -> None:
+    """Nested dates should be used for sorting."""
+    conferences: list[dict[str, typing.Any]] = [
+        {
+            "name": "PyCascades",
+            "dates": {
+                "status": "approximate",
+                "label": "March 2027",
+                "earliest": date(2027, 3, 1),
+                "latest": date(2027, 3, 31),
+            },
+        }
+    ]
+    new_conf: dict[str, typing.Any] = {
+        "name": "FOSDEM",
+        "dates": {
+            "status": "tentative",
+            "start": date(2027, 1, 30),
+            "end": date(2027, 1, 31),
+        },
+    }
+
+    updated = add_new_conference.insert_sorted(conferences, new_conf)
+
+    assert [conf["name"] for conf in updated] == ["FOSDEM", "PyCascades"]
+
+
 def test_validate_country_normalises_name() -> None:
     """Country names should be normalised to alpha-2 codes."""
     conf: dict[str, typing.Any] = {"country": "United Kingdom"}
@@ -68,6 +95,21 @@ def test_normalise_end_field_defaults_single_day_date() -> None:
     assert conf["end"] == date(2026, 4, 10)
 
 
+def test_normalise_end_field_defaults_nested_exact_date() -> None:
+    """Nested exact dates should get a default end date."""
+    conf: dict[str, typing.Any] = {
+        "name": "PyCon",
+        "dates": {
+            "status": "exact",
+            "start": date(2026, 4, 10),
+        },
+    }
+
+    add_new_conference.normalise_end_field(conf, "plain text")
+
+    assert conf["dates"]["end"] == date(2026, 4, 10)
+
+
 def test_normalise_end_field_sets_geomob_end_time() -> None:
     """Geomob conferences should default to a 22:00 end time."""
     conf: dict[str, typing.Any] = {