Expand /oncall date parser to accept more formats

Users entering everyday forms like 7/3/26 hit a generic parse
failure because the parser only accepted four-digit years and a
bare m/d. Add two-digit-year and month-name (with optional
ordinal/year) formats, treating explicit-year inputs as fixed and
keeping the year-less roll-forward for bare m/d. Update the help
text and per-command parse hints to match.

Refs: #133

src/shared/shared/blocks.py

@@ -439,7 +439,7 @@ def build_help_blocks(is_admin: bool = False) -> list[dict]:
         "`/oncall rate <ext> <amount>` — Set a person's rate\n"
         "`/oncall roster` — Show all registered employees\n"
         "`/oncall help` — Show this help message\n\n"
-        "_Dates can be: today, tomorrow, monday, friday, 4/5, 2026-04-05_"
+        "_Dates can be: today, tomorrow, monday, friday, 4/5, 7/3/26, jul 3, 2026-04-05_"
     )
     if is_admin:
         text += (

src/slack-bot/app.py

@@ -57,8 +57,27 @@ DAY_NAMES = [
 ]
 
 
+# Formats carrying an explicit year — parsed as-is, never rolled forward.
+_DATED_FORMATS = (
+    "%Y-%m-%d",
+    "%m/%d/%Y",
+    "%m/%d/%y",
+    "%m-%d-%y",
+    "%b %d %Y",
+    "%B %d %Y",
+    "%b %d %y",
+    "%B %d %y",
+)
+# Year-less formats — stamped with the current year, then rolled to next year
+# if already more than a day in the past.
+_UNDATED_FORMATS = ("%m/%d", "%m-%d", "%b %d", "%B %d")
+
+_ORDINAL_RE = re.compile(r"(\d+)(st|nd|rd|th)\b")
+
+
 def parse_date(text: str) -> datetime | None:
-    """Parse flexible date input: today, tomorrow, day names, m/d, YYYY-MM-DD."""
+    """Parse flexible date input: today, tomorrow, day names, m/d, m/d/yy,
+    YYYY-MM-DD, and month-name forms (e.g. ``jul 3``, ``july 3rd 2026``)."""
     now = datetime.now(EASTERN)
     text = text.strip().lower()
 
@@ -75,13 +94,19 @@ def parse_date(text: str) -> datetime | None:
             delta = 7
         return now + timedelta(days=delta)
 
-    for fmt in ("%Y-%m-%d", "%m/%d/%Y", "%m/%d", "%m-%d"):
+    candidate = _ORDINAL_RE.sub(r"\1", text)
+
+    for fmt in _DATED_FORMATS:
         try:
-            parsed = datetime.strptime(text, fmt)
-            if "%Y" not in fmt:
-                parsed = parsed.replace(year=now.year)
-                if parsed.replace(tzinfo=EASTERN) < now - timedelta(days=1):
-                    parsed = parsed.replace(year=now.year + 1)
+            return datetime.strptime(candidate, fmt).replace(tzinfo=EASTERN)
+        except ValueError:
+            continue
+
+    for fmt in _UNDATED_FORMATS:
+        try:
+            parsed = datetime.strptime(candidate, fmt).replace(year=now.year)
+            if parsed.replace(tzinfo=EASTERN) < now - timedelta(days=1):
+                parsed = parsed.replace(year=now.year + 1)
             return parsed.replace(tzinfo=EASTERN)
         except ValueError:
             continue
@@ -673,7 +698,7 @@ def _handle_pick(
     date = parse_date(date_text)
     if not date:
         respond(
-            text=f"Couldn't parse date: `{date_text}`. Try: today, tomorrow, friday, 4/5, 2026-04-05"
+            text=f"Couldn't parse date: `{date_text}`. Try: today, tomorrow, friday, 4/5, 7/3/26, jul 3, 2026-04-05"
         )
         return
 
@@ -907,7 +932,7 @@ def _handle_drop(
     date = parse_date(parts[1])
     if not date:
         respond(
-            text=f"Couldn't parse date: `{parts[1]}`. Try: today, tomorrow, friday, 4/5, 2026-04-05"
+            text=f"Couldn't parse date: `{parts[1]}`. Try: today, tomorrow, friday, 4/5, 7/3/26, jul 3, 2026-04-05"
         )
         return
 

tests/slack_bot/test_parse_date.py

@@ -54,6 +54,58 @@ def test_case_insensitive(slackbot_app):
     assert slackbot_app.parse_date("  FRIDAY ").strftime("%Y-%m-%d") == "2026-06-05"
 
 
+@freeze_time(FROZEN)
+def test_two_digit_year_slash(slackbot_app):
+    assert slackbot_app.parse_date("7/3/26").strftime("%Y-%m-%d") == "2026-07-03"
+
+
+@freeze_time(FROZEN)
+def test_two_digit_year_padded(slackbot_app):
+    assert slackbot_app.parse_date("07/03/26").strftime("%Y-%m-%d") == "2026-07-03"
+
+
+@freeze_time(FROZEN)
+def test_two_digit_year_dash(slackbot_app):
+    assert slackbot_app.parse_date("7-3-26").strftime("%Y-%m-%d") == "2026-07-03"
+
+
+@freeze_time(FROZEN)
+def test_two_digit_year_past_not_rolled(slackbot_app):
+    # Explicit two-digit year in the past stays put — no roll-forward.
+    assert slackbot_app.parse_date("1/1/26").strftime("%Y-%m-%d") == "2026-01-01"
+
+
+@freeze_time(FROZEN)
+def test_month_name_short(slackbot_app):
+    assert slackbot_app.parse_date("jul 3").strftime("%Y-%m-%d") == "2026-07-03"
+
+
+@freeze_time(FROZEN)
+def test_month_name_full(slackbot_app):
+    assert slackbot_app.parse_date("july 3").strftime("%Y-%m-%d") == "2026-07-03"
+
+
+@freeze_time(FROZEN)
+def test_month_name_with_year(slackbot_app):
+    assert slackbot_app.parse_date("july 3 2026").strftime("%Y-%m-%d") == "2026-07-03"
+
+
+@freeze_time(FROZEN)
+def test_month_name_ordinal(slackbot_app):
+    assert slackbot_app.parse_date("july 3rd").strftime("%Y-%m-%d") == "2026-07-03"
+
+
+@freeze_time(FROZEN)
+def test_month_name_past_wraps_to_next_year(slackbot_app):
+    # Year-less month name in the past rolls forward, like m/d.
+    assert slackbot_app.parse_date("jan 1").year == 2027
+
+
+@freeze_time(FROZEN)
+def test_eastern_tz_stamped(slackbot_app):
+    assert slackbot_app.parse_date("7/3/26").tzinfo is not None
+
+
 @freeze_time(FROZEN)
 def test_invalid_returns_none(slackbot_app):
     assert slackbot_app.parse_date("notaday") is None