fix: calendar check-in digest drops events 7-8 days out (#1249)

* fix: close 1-day gap in calendar digest windows (events ~7-8 days out)

* test: calendar digest windows are contiguous and cover 7-8 day events

tests/test_digest_windows.py

@@ -0,0 +1,22 @@
+"""Tests for the calendar check-in digest windows (src/task_scheduler.py)."""
+from datetime import datetime, timedelta
+
+from src.task_scheduler import _digest_windows
+
+
+def test_windows_are_contiguous_with_no_gap():
+    now = datetime(2026, 6, 2, 9, 0, 0)
+    windows = _digest_windows(now)
+    # Each window starts exactly where the previous ended — no gap between
+    # buckets (the old code jumped from now+7d to now+8d, dropping events).
+    for (prev, cur) in zip(windows, windows[1:]):
+        assert cur[1] == prev[2]
+    assert windows[0][1] == now
+    assert windows[-1][2] == now + timedelta(days=30)
+
+
+def test_event_seven_and_a_half_days_out_is_covered():
+    now = datetime(2026, 6, 2, 9, 0, 0)
+    event = now + timedelta(days=7, hours=12)  # fell in the old 7-8 day gap
+    buckets = [label for label, start, end in _digest_windows(now) if start <= event <= end]
+    assert buckets, "event ~7.5 days out should land in a digest window"