[Bug]: completed recurrent task instance does not show in calendar_default view

[amglez]

Bug Description

Exactly as the title says: when I wark a recurrent task as complete and it generates the next task data, the old completed instance disappears from the calendar view.

But it show's allright on the agenda view, for example.

Steps to Reproduce

1. Have a recurring task with showCompletedRecurringInstances: true in the .base view options.
2. Open the tasknotesCalendar view in any time-grid mode (timeGridDay, timeGridCustom, or timeGridWeek).
3. Confirm the task's current scheduled instance is visible on the calendar.
4. Mark the recurring task as complete (the plugin advances scheduled to the next occurrence and records the completed date in complete_instances).
5. The completed instance disappears from the calendar. It does not show as a completed event.

When exactly this happens:

The instance always disappears when completing in timeGridCustom / timeGridDay (1-day view), because the completed date is always the last day of the 1-day range.

In timeGridWeek, it only disappears when the task is completed on the last day of the visible week (e.g. Saturday if the week starts on Sunday, Sunday if it starts on Monday).

The listWeek (agenda) view is not affected: completed instances always appear there regardless of which day they fall on.

Confirmed reproduction matrix (CEST = UTC+2):

View	Completed today (Mon 15 Jun)	Completed Sat 14 Jun
timeGridCustom, 1 day	✗ never visible	—
timeGridWeek Sun–Sat, previous week	—	✗ not visible
timeGridWeek Sun–Sat, current week	✓ visible	—
listWeek (agenda)	✓ visible	✓ visible

TaskNotes Debug Info

Affected Task Frontmatter

Relevant Bases File Content

filters:
and:
- file.hasTag("task")
formulas:
priorityWeight: if(priority=="none",0,if(priority=="low",1,if(priority=="normal",2,if(priority=="high",3,999))))
daysUntilDue: if(due, ((number(date(due)) - number(today())) / 86400000).floor(), null)
daysUntilScheduled: if(scheduled, ((number(date(scheduled)) - number(today())) / 86400000).floor(), null)
daysSinceCreated: ((number(now()) - number(file.ctime)) / 86400000).floor()
daysSinceModified: ((number(now()) - number(file.mtime)) / 86400000).floor()
isOverdue: due && date(due) < today() && status != "done"
isDueToday: due && date(due).date() == today()
isDueThisWeek: due && date(due) >= today() && date(due) <= today() + "7d"
isScheduledToday: scheduled && date(scheduled).date() == today()
isRecurring: recurrence && !recurrence.isEmpty()
hasTimeEstimate: timeEstimate && timeEstimate > 0
timeRemaining: if(timeEstimate && timeEstimate > 0, timeEstimate - if(timeEntries, list(timeEntries).filter(value.endTime).map((number(date(value.endTime)) - number(date(value.startTime))) / 60000).reduce(acc + value, 0), 0), null)
efficiencyRatio: if(timeEstimate && timeEstimate > 0 && timeEntries, (list(timeEntries).filter(value.endTime).map((number(date(value.endTime)) - number(date(value.startTime))) / 60000).reduce(acc + value, 0) / timeEstimate * 100).round(), null)
timeTrackedThisWeek: if(timeEntries, list(timeEntries).filter(value.endTime && date(value.startTime) >= today() - "7d").map((number(date(value.endTime)) - number(date(value.startTime))) / 60000).reduce(acc + value, 0).round(), 0)
timeTrackedToday: if(timeEntries, list(timeEntries).filter(value.endTime && date(value.startTime).date() == today()).map((number(date(value.endTime)) - number(date(value.startTime))) / 60000).reduce(acc + value, 0).round(), 0)
dueMonth: if(due, date(due).format("YYYY-MM"), "No due date")
dueWeek: if(due, date(due).format("YYYY-[W]WW"), "No due date")
scheduledMonth: if(scheduled, date(scheduled).format("YYYY-MM"), "Not scheduled")
scheduledWeek: if(scheduled, date(scheduled).format("YYYY-[W]WW"), "Not scheduled")
dueDateCategory: if(!due, "No due date", if(date(due) < today(), "Overdue", if(date(due).date() == today(), "Today", if(date(due).date() == today() + "1d", "Tomorrow", if(date(due) <= today() + "7d", "This week", "Later")))))
timeEstimateCategory: if(!timeEstimate || timeEstimate == 0 || timeEstimate == null, "No estimate", if(timeEstimate < 30, "Quick (<30m)", if(timeEstimate <= 120, "Medium (30m-2h)", "Long (>2h)")))
ageCategory: if(((number(now()) - number(file.ctime)) / 86400000) < 1, "Today", if(((number(now()) - number(file.ctime)) / 86400000) < 7, "This week", if(((number(now()) - number(file.ctime)) / 86400000) < 30, "This month", "Older")))
createdMonth: file.ctime.format("YYYY-MM")
modifiedMonth: file.mtime.format("YYYY-MM")
priorityCategory: if(priority=="none","None",if(priority=="low","Low",if(priority=="normal","Normal",if(priority=="high","High","No priority"))))
projectCount: if(!projects || list(projects).length == 0, "No projects", if(list(projects).length == 1, "Single project", "Multiple projects"))
contextCount: if(!contexts || list(contexts).length == 0, "No contexts", if(list(contexts).length == 1, "Single context", "Multiple contexts"))
trackingStatus: if(!timeEstimate || timeEstimate == 0 || timeEstimate == null, "No estimate", if(!timeEntries || list(timeEntries).length == 0, "Not started", if(formula.efficiencyRatio < 100, "Under estimate", "Over estimate")))
nextDate: if(due && scheduled, if(date(due) < date(scheduled), due, scheduled), if(due, due, scheduled))
daysUntilNext: if(due && scheduled, min(formula.daysUntilDue, formula.daysUntilScheduled), if(due, formula.daysUntilDue, formula.daysUntilScheduled))
hasDate: due || scheduled
isToday: (due && date(due).date() == today()) || (scheduled && date(scheduled).date() == today())
isThisWeek: (due && date(due) >= today() && date(due) <= today() + "7d") || (scheduled && date(scheduled) >= today() && date(scheduled) <= today() + "7d")
nextDateCategory: if(!due && !scheduled, "No date", if((due && date(due) < today()) || (scheduled && date(scheduled) < today()), "Overdue/Past", if((due && date(due).date() == today()) || (scheduled && date(scheduled).date() == today()), "Today", if((due && date(due).date() == today() + "1d") || (scheduled && date(scheduled).date() == today() + "1d"), "Tomorrow", if((due && date(due) <= today() + "7d") || (scheduled && date(scheduled) <= today() + "7d"), "This week", "Later")))))
nextDateMonth: if(due && scheduled, if(date(due) < date(scheduled), date(due).format("YYYY-MM"), date(scheduled).format("YYYY-MM")), if(due, date(due).format("YYYY-MM"), if(scheduled, date(scheduled).format("YYYY-MM"), "No date")))
nextDateWeek: if(due && scheduled, if(date(due) < date(scheduled), date(due).format("YYYY-[W]WW"), date(scheduled).format("YYYY-[W]WW")), if(due, date(due).format("YYYY-[W]WW"), if(scheduled, date(scheduled).format("YYYY-[W]WW"), "No date")))
urgencyScore: if(!due && !scheduled, formula.priorityWeight, formula.priorityWeight + max(0, 10 - formula.daysUntilNext))
timeTrackedFormatted: if(timeEntries, if(list(timeEntries).filter(value.endTime).map((number(date(value.endTime)) - number(date(value.startTime))) / 60000).reduce(acc + value, 0) >= 60, (list(timeEntries).filter(value.endTime).map((number(date(value.endTime)) - number(date(value.startTime))) / 60000).reduce(acc + value, 0) / 60).floor() + "h " + (list(timeEntries).filter(value.endTime).map((number(date(value.endTime)) - number(date(value.startTime))) / 60000).reduce(acc + value, 0) % 60).round() + "m", list(timeEntries).filter(value.endTime).map((number(date(value.endTime)) - number(date(value.startTime))) / 60000).reduce(acc + value, 0).round() + "m"), "0m")
dueDateDisplay: if(!due, "", if(date(due).date() == today(), "Today", if(date(due).date() == today() + "1d", "Tomorrow", if(date(due).date() == today() - "1d", "Yesterday", if(date(due) < today(), formula.daysUntilDue * -1 + "d ago", if(date(due) <= today() + "7d", date(due).format("ddd"), date(due).format("MMM D")))))))
views:

• type: tasknotesCalendar
  name: Calendar
  order:
  • status
  • priority
  • due
  • scheduled
  • projects
  • contexts
  • file.tags
  • blockedBy
  • file.name
  • recurrence
  • complete_instances
  • file.tasks
    options:
    showScheduled: true
    showDue: true
    showRecurring: true
    showTimeEntries: true
    showTimeblocks: true
    showPropertyBasedEvents: true
    calendarView: timeGridWeek
    customDayCount: 3
    firstDay: 0
    slotMinTime: 06:00:00
    slotMaxTime: 22:00:00
    slotDuration: 00:30:00
    calendarView: timeGridCustom
    slotMinTime: 08:30:00
    firstDay: "0"
    customDayCount: 1
    listDayCount: 1
    slotMaxTime: 24:00:00
    todayColumnWidthMultiplier: 1.5
    scrollTime: 09:30:00
    showCompletedRecurringInstances: true
    showScheduledToDueSpan: true

Relevant Settings or Customizations

• Timezone: Europe/Madrid (CEST, UTC+2 in summer)
• firstDay: 0 (week starts on Sunday)
• calendarView: timeGridCustom with customDayCount: 1 (primary affected view)
• showCompletedRecurringInstances: true

Console Errors or Logs

Screenshots or Screen Recording

No response

[amglez]

Root cause identified (after reading the source)

I've traced the bug to an exact location in src/bases/calendar-core.ts. It's a UTC vs. local time mismatch that only surfaces in time-grid views for users in UTC+ timezones.

---

Why the incomplete task appears but the completed one doesn't

The two states go through different code paths with inconsistent date handling:

Before completing — FullCalendar shows the task via createNextScheduledEvent, which is filtered by isDateInVisibleRange. That function compares timestamps in local time → works correctly.

After completing — task.scheduled advances to the next occurrence, and the completed date moves into complete_instances. The event now has to go through getRecordedRecurringInstanceDatesInRange, which does this:

// src/bases/calendar-core.ts ~line 1291
const startDateOnly = formatDateForStorage(startDate); // extracts UTC day
const endDateOnly   = formatDateForStorage(endDate);   // extracts UTC day

if (date >= startDateOnly && date < endDateOnly) { ... }

formatDateForStorage uses getUTCDate() / getUTCMonth() / getUTCFullYear(). But FullCalendar's fetchInfo.end is midnight in local time. For any user in a UTC+ timezone, that local midnight is still the same day in UTC:

// User in CEST (UTC+2), viewing Monday 15 June:
fetchInfo.end  = 2026-06-16T00:00:00 CEST  (local midnight)
               = 2026-06-15T22:00:00Z       (still "the 15th" in UTC)
endDateOnly    = "2026-06-15"               ← one day short

complete_instances = ["2026-06-15"]
"2026-06-15" < "2026-06-15"  →  false  →  event dropped

In a 1-day view, the completed date is always exactly at the boundary → always excluded.
In a weekly view, only the last day of the week hits the boundary.
In listWeek, the range is 7 days wide, so the boundary is never an issue.

---

A second occurrence of the same bug

The same formatDateForStorage(endDate) pattern appears a few lines earlier in generateRecurringTaskInstances (~line 1177), where it filters RRULE-generated instances:

const endDateOnly = formatDateForStorage(endDate);
if (instanceDate >= endDateOnly) { continue; }

This would also incorrectly skip projected instances scheduled on the last visible day for UTC+ users.

---

Proposed fix

date-fns/format is already imported in the file and produces a local-time date string, which is what FullCalendar's boundaries represent:

// getRecordedRecurringInstanceDatesInRange (~line 1291)
// Before:
const startDateOnly = formatDateForStorage(startDate);
const endDateOnly   = formatDateForStorage(endDate);

// After:
const startDateOnly = format(startDate, "yyyy-MM-dd");
const endDateOnly   = format(endDate,   "yyyy-MM-dd");

// generateRecurringTaskInstances (~line 1177)
// Before:
const endDateOnly = formatDateForStorage(endDate);

// After:
const endDateOnly = format(endDate, "yyyy-MM-dd");

This makes both functions consistent with isDateInVisibleRange, which already uses local time throughout.