feat(normalizer): feast + season resolution

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

tools/import-normalizer/dates.py

@@ -1,5 +1,42 @@
 """Tolerant historical date parsing for the family archive."""
 import datetime
+from enum import StrEnum
+import config
+
+
+class Precision(StrEnum):
+    DAY = "DAY"
+    MONTH = "MONTH"
+    SEASON = "SEASON"
+    YEAR = "YEAR"
+    RANGE = "RANGE"
+    APPROX = "APPROX"
+    UNKNOWN = "UNKNOWN"
+
+
+def _advent_sunday(year: int, n: int) -> datetime.date:
+    """n-th Advent (1..4). 4th Advent = last Sunday on/before Dec 24."""
+    dec24 = datetime.date(year, 12, 24)
+    back_to_sunday = (dec24.weekday() - 6) % 7  # Mon=0..Sun=6
+    fourth = dec24 - datetime.timedelta(days=back_to_sunday)
+    return fourth - datetime.timedelta(days=(4 - n) * 7)
+
+
+def resolve_feast_or_season(token: str, year: int):
+    """Return (iso, Precision) for a known feast/season token, else None."""
+    key = " ".join(token.lower().split()).strip(" .")
+    if key in config.MOVABLE_FEASTS:
+        d = easter(year) + datetime.timedelta(days=config.MOVABLE_FEASTS[key])
+        return d.isoformat(), Precision.DAY
+    if key in config.FIXED_FEASTS:
+        month, day = config.FIXED_FEASTS[key]
+        return datetime.date(year, month, day).isoformat(), Precision.DAY
+    advent = {"1. advent": 1, "2. advent": 2, "3. advent": 3, "4. advent": 4, "advent": 1}
+    if key in advent:
+        return _advent_sunday(year, advent[key]).isoformat(), Precision.DAY
+    if key in config.SEASON_MONTHS:
+        return datetime.date(year, config.SEASON_MONTHS[key], 1).isoformat(), Precision.SEASON
+    return None
 
 
 def easter(year: int) -> datetime.date:

tools/import-normalizer/tests/test_dates.py

@@ -1,5 +1,6 @@
 import datetime
 import dates
+from dates import Precision
 
 def test_easter_known_years():
     # Anonymous Gregorian algorithm — verified against published tables
@@ -7,3 +8,19 @@ def test_easter_known_years():
     assert dates.easter(2000) == datetime.date(2000, 4, 23)
     assert dates.easter(1922) == datetime.date(1922, 4, 16)
     assert dates.easter(1888) == datetime.date(1888, 4, 1)
+
+def test_resolve_feast_movable():
+    assert dates.resolve_feast_or_season("Pfingsten", 1922) == ("1922-06-04", Precision.DAY)
+    assert dates.resolve_feast_or_season("Ostern", 2024) == ("2024-03-31", Precision.DAY)
+    assert dates.resolve_feast_or_season("Pfingstmontag", 1922) == ("1922-06-05", Precision.DAY)
+
+def test_resolve_feast_fixed():
+    assert dates.resolve_feast_or_season("Weihnachten", 1900) == ("1900-12-25", Precision.DAY)
+    assert dates.resolve_feast_or_season("Neujahr", 1910) == ("1910-01-01", Precision.DAY)
+
+def test_resolve_season():
+    assert dates.resolve_feast_or_season("Herbst", 1913) == ("1913-10-01", Precision.SEASON)
+    assert dates.resolve_feast_or_season("Sommer", 1910) == ("1910-07-01", Precision.SEASON)
+
+def test_resolve_unknown_token_returns_none():
+    assert dates.resolve_feast_or_season("Freitag", 1919) is None