diff --git a/src/documents/search/_query.py b/src/documents/search/_query.py
index dbedc2973..1bd31b804 100644
--- a/src/documents/search/_query.py
+++ b/src/documents/search/_query.py
@@ -25,16 +25,25 @@ _REGEX_TIMEOUT: Final[float] = 1.0
 
 _DATE_ONLY_FIELDS = frozenset({"created"})
 
+_TODAY: Final[str] = "today"
+_YESTERDAY: Final[str] = "yesterday"
+_PREVIOUS_WEEK: Final[str] = "previous week"
+_THIS_MONTH: Final[str] = "this month"
+_PREVIOUS_MONTH: Final[str] = "previous month"
+_THIS_YEAR: Final[str] = "this year"
+_PREVIOUS_YEAR: Final[str] = "previous year"
+_PREVIOUS_QUARTER: Final[str] = "previous quarter"
+
 _DATE_KEYWORDS = frozenset(
     {
-        "today",
-        "yesterday",
-        "previous week",
-        "this month",
-        "previous month",
-        "this year",
-        "previous year",
-        "previous quarter",
+        _TODAY,
+        _YESTERDAY,
+        _PREVIOUS_WEEK,
+        _THIS_MONTH,
+        _PREVIOUS_MONTH,
+        _THIS_YEAR,
+        _PREVIOUS_YEAR,
+        _PREVIOUS_QUARTER,
     },
 )
 
@@ -86,41 +95,41 @@ def _date_only_range(keyword: str, tz: tzinfo) -> str:
     def _quarter_start(d: date) -> date:
         return date(d.year, ((d.month - 1) // 3) * 3 + 1, 1)
 
-    if keyword == "today":
+    if keyword == _TODAY:
         lo = datetime(today.year, today.month, today.day, tzinfo=UTC)
         return _iso_range(lo, lo + timedelta(days=1))
-    if keyword == "yesterday":
+    if keyword == _YESTERDAY:
         y = today - timedelta(days=1)
         lo = datetime(y.year, y.month, y.day, tzinfo=UTC)
         hi = datetime(today.year, today.month, today.day, tzinfo=UTC)
         return _iso_range(lo, hi)
-    if keyword == "previous week":
+    if keyword == _PREVIOUS_WEEK:
         this_mon = today - timedelta(days=today.weekday())
         last_mon = this_mon - timedelta(weeks=1)
         lo = datetime(last_mon.year, last_mon.month, last_mon.day, tzinfo=UTC)
         hi = datetime(this_mon.year, this_mon.month, this_mon.day, tzinfo=UTC)
         return _iso_range(lo, hi)
-    if keyword == "this month":
+    if keyword == _THIS_MONTH:
         lo = datetime(today.year, today.month, 1, tzinfo=UTC)
         if today.month == 12:
             hi = datetime(today.year + 1, 1, 1, tzinfo=UTC)
         else:
             hi = datetime(today.year, today.month + 1, 1, tzinfo=UTC)
         return _iso_range(lo, hi)
-    if keyword == "previous month":
+    if keyword == _PREVIOUS_MONTH:
         if today.month == 1:
             lo = datetime(today.year - 1, 12, 1, tzinfo=UTC)
         else:
             lo = datetime(today.year, today.month - 1, 1, tzinfo=UTC)
         hi = datetime(today.year, today.month, 1, tzinfo=UTC)
         return _iso_range(lo, hi)
-    if keyword == "this year":
+    if keyword == _THIS_YEAR:
         lo = datetime(today.year, 1, 1, tzinfo=UTC)
         return _iso_range(lo, datetime(today.year + 1, 1, 1, tzinfo=UTC))
-    if keyword == "previous year":
+    if keyword == _PREVIOUS_YEAR:
         lo = datetime(today.year - 1, 1, 1, tzinfo=UTC)
         return _iso_range(lo, datetime(today.year, 1, 1, tzinfo=UTC))
-    if keyword == "previous quarter":
+    if keyword == _PREVIOUS_QUARTER:
         this_quarter = _quarter_start(today)
         last_quarter = this_quarter - relativedelta(months=3)
         lo = datetime(
@@ -154,40 +163,40 @@ def _datetime_range(keyword: str, tz: tzinfo) -> str:
     def _quarter_start(d: date) -> date:
         return date(d.year, ((d.month - 1) // 3) * 3 + 1, 1)
 
-    if keyword == "today":
+    if keyword == _TODAY:
         return _iso_range(_midnight(today), _midnight(today + timedelta(days=1)))
-    if keyword == "yesterday":
+    if keyword == _YESTERDAY:
         y = today - timedelta(days=1)
         return _iso_range(_midnight(y), _midnight(today))
-    if keyword == "previous week":
+    if keyword == _PREVIOUS_WEEK:
         this_mon = today - timedelta(days=today.weekday())
         last_mon = this_mon - timedelta(weeks=1)
         return _iso_range(_midnight(last_mon), _midnight(this_mon))
-    if keyword == "this month":
+    if keyword == _THIS_MONTH:
         first = today.replace(day=1)
         if today.month == 12:
             next_first = date(today.year + 1, 1, 1)
         else:
             next_first = date(today.year, today.month + 1, 1)
         return _iso_range(_midnight(first), _midnight(next_first))
-    if keyword == "previous month":
+    if keyword == _PREVIOUS_MONTH:
         this_first = today.replace(day=1)
         if today.month == 1:
             last_first = date(today.year - 1, 12, 1)
         else:
             last_first = date(today.year, today.month - 1, 1)
         return _iso_range(_midnight(last_first), _midnight(this_first))
-    if keyword == "this year":
+    if keyword == _THIS_YEAR:
         return _iso_range(
             _midnight(date(today.year, 1, 1)),
             _midnight(date(today.year + 1, 1, 1)),
         )
-    if keyword == "previous year":
+    if keyword == _PREVIOUS_YEAR:
         return _iso_range(
             _midnight(date(today.year - 1, 1, 1)),
             _midnight(date(today.year, 1, 1)),
         )
-    if keyword == "previous quarter":
+    if keyword == _PREVIOUS_QUARTER:
         this_quarter = _quarter_start(today)
         last_quarter = this_quarter - relativedelta(months=3)
         return _iso_range(_midnight(last_quarter), _midnight(this_quarter))