feat(normalizer): roman-numeral month matcher

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tools/import-normalizer/dates.py

@@ -116,8 +116,26 @@ def _match_numeric(s):
         return None
 
 
+_ROMAN_RE = re.compile(r"(\d{1,2})\.\s*([IVXLC]+)\.?\s*(\d{2,4})", re.I)
+
+
+def _match_roman(s):
+    m = _ROMAN_RE.fullmatch(s)
+    if not m:
+        return None
+    day = int(m.group(1))
+    month = config.ROMAN_MONTHS.get(m.group(2).lower())
+    year = expand_year(m.group(3))
+    if not month or year is None:
+        return None
+    try:
+        return datetime.date(year, month, day).isoformat(), Precision.DAY
+    except ValueError:
+        return None
+
+
 # Matchers are tried in order. Later tasks append to this list.
-_MATCHERS = [_match_iso, _match_numeric]
+_MATCHERS = [_match_iso, _match_numeric, _match_roman]
 
 
 def parse_date(raw: str, date_overrides: dict | None = None) -> ParsedDate:

tools/import-normalizer/tests/test_dates.py

@@ -63,3 +63,9 @@ def test_parse_leading_qualifier_is_approx():
     r = dates.parse_date("nach 1.5.1900")  # qualifier stripped, numeric date salvaged, precision APPROX
     assert r.iso == "1900-05-01"
     assert r.precision == Precision.APPROX
+
+def test_parse_roman_months():
+    assert dates.parse_date("22.III.18").iso == "1918-03-22"
+    assert dates.parse_date("19.XII.1954").iso == "1954-12-19"
+    assert dates.parse_date("1.III.27").iso == "1927-03-01"
+    assert dates.parse_date("22.III.18").precision == Precision.DAY