Fix Google Calendar task sync reliability and rendering

Author: martin-forge

docs/releases/unreleased.md

@@ -23,3 +23,22 @@ Example:
 ```
 
 -->
+
+## Fixed
+
+- (#1696) Fixed Google Calendar recurring tasks creating duplicate moved occurrences instead of converging on one series instance plus one detached exception event
+  - Scheduled-anchor recurring moves now preserve the original series date, add the correct Google `EXDATE`, and create or remove the detached Google event as the moved occurrence is resolved
+  - Archive, delete, and retry flows now clean up both the recurring master link and any detached exception link so stale Google events do not linger
+  - Thanks to @martin-forge for reporting, reproducing, and patching the recurring exception sync failure
+- (#1823) Fixed zero-duration timed external calendar events rendering on multiple days in list-style calendar views
+  - Adds a minimal display duration before passing point-in-time external events to FullCalendar
+  - Preserves the original provider event data for context menus and debugging
+  - Thanks to @martin-forge for reporting and debugging
+- Persist failed Google Calendar task-event deletions in plugin data and retry them after restart or reconnect, preventing orphaned task events when a task file is deleted while Google cleanup fails or sync is not ready.
+- Track exported Google Calendar task events in plugin data so startup can recover cleanup for task files deleted while Obsidian was closed.
+- Persist Google Calendar task sync requests while Google Calendar is not ready and replay the current task state after reconnect for scheduled, due, or both-date calendar modes.
+- Restore cancelled Google Calendar event tombstones when a task is synced to an existing event ID, so deleted-but-still-addressable events become visible again.
+- Prevent duplicate Google Calendar task events when concurrent syncs race before the newly created event ID reaches Obsidian metadata.
+- Prevent pending intermediate status updates from overwriting completed Google Calendar task events when users quickly cycle a task to done.
+- Mark Google Calendar events as completed when tasks were already done before they became calendar-eligible.
+- Google Calendar task descriptions now use mobile-friendly plain text for Obsidian links and display labels for wiki-style project/context links.

src/bases/calendar-core.ts

@@ -578,11 +578,17 @@ export function createICSEvent(icsEvent: ICSEvent, plugin: TaskNotesPlugin): Cal
 			subscriptionName = subscription.name;
 		}
 
+		const { start, end } = normalizeExternalTimedEventRange(
+			icsEvent.start,
+			icsEvent.end,
+			icsEvent.allDay
+		);
+
 		return {
 			id: icsEvent.id,
 			title: icsEvent.title,
-			start: icsEvent.start,
-			end: icsEvent.end,
+			start: start,
+			end: end,
 			allDay: icsEvent.allDay,
 			backgroundColor: backgroundColor,
 			borderColor: borderColor,
@@ -602,6 +608,60 @@ export function createICSEvent(icsEvent: ICSEvent, plugin: TaskNotesPlugin): Cal
 	}
 }
 
+/**
+ * FullCalendar list views can render a timed external event under multiple day
+ * headers when the provider supplies a true zero-duration range (end === start).
+ * Clamp those point-in-time external events to a minimal positive duration
+ * before handing them to FullCalendar, while preserving the raw provider event
+ * unchanged in extendedProps for display and debugging.
+ */
+function normalizeExternalTimedEventRange(
+	start: string,
+	end: string | undefined,
+	allDay: boolean
+): { start: string; end?: string } {
+	if (allDay || !end) {
+		return { start, end };
+	}
+
+	const startDate = new Date(start);
+	const endDate = new Date(end);
+
+	if (
+		Number.isNaN(startDate.getTime()) ||
+		Number.isNaN(endDate.getTime()) ||
+		endDate.getTime() !== startDate.getTime()
+	) {
+		return { start, end };
+	}
+
+	const normalizedEnd = new Date(endDate.getTime() + 1);
+	return {
+		start,
+		end: formatExternalTimedEventEnd(normalizedEnd, end),
+	};
+}
+
+function formatExternalTimedEventEnd(date: Date, originalEnd: string): string {
+	if (/Z$/i.test(originalEnd)) {
+		return date.toISOString();
+	}
+
+	const offsetMatch = originalEnd.match(/([+-])(\d{2}):?(\d{2})$/);
+	if (offsetMatch) {
+		const [, sign, hours, minutes] = offsetMatch;
+		const offsetMinutes = Number(hours) * 60 + Number(minutes);
+		const offsetMs = offsetMinutes * 60 * 1000 * (sign === "+" ? 1 : -1);
+		const shifted = new Date(date.getTime() + offsetMs);
+		const pad = (value: number, length = 2) => String(value).padStart(length, "0");
+		const datePart = `${shifted.getUTCFullYear()}-${pad(shifted.getUTCMonth() + 1)}-${pad(shifted.getUTCDate())}`;
+		const timePart = `${pad(shifted.getUTCHours())}:${pad(shifted.getUTCMinutes())}:${pad(shifted.getUTCSeconds())}.${pad(shifted.getUTCMilliseconds(), 3)}`;
+		return `${datePart}T${timePart}${sign}${hours}:${minutes}`;
+	}
+
+	return format(date, "yyyy-MM-dd'T'HH:mm:ss.SSS");
+}
+
 /**
  * Get recurring time from task recurrence rule
  */
@@ -744,6 +804,75 @@ export function createRecurringEvent(
 	};
 }
 
+function buildRecurringInstanceExclusionSet(
+	task: TaskInfo,
+	nextScheduledDate: string
+): Set<string> {
+	const exclusions = new Set<string>();
+	const normalizeDateValue = (value: unknown): string | undefined => {
+		if (typeof value === "string") {
+			const normalized = getDatePart(value);
+			return typeof normalized === "string" && normalized ? normalized : undefined;
+		}
+		if (value instanceof Date) {
+			if (Number.isNaN(value.getTime())) return undefined;
+			return formatDateForStorage(value);
+		}
+		if (typeof value === "number") {
+			const date = new Date(value);
+			if (Number.isNaN(date.getTime())) return undefined;
+			return formatDateForStorage(date);
+		}
+		if (value && typeof value === "object") {
+			const record = value as Record<string, unknown>;
+			if (record.date instanceof Date) {
+				if (Number.isNaN(record.date.getTime())) return undefined;
+				return formatDateForStorage(record.date);
+			}
+			if (typeof record.data === "string") {
+				return normalizeDateValue(record.data);
+			}
+			if (typeof (value as { toISOString?: () => string }).toISOString === "function") {
+				try {
+					return normalizeDateValue(
+						(value as { toISOString: () => string }).toISOString()
+					);
+				} catch {
+					return undefined;
+				}
+			}
+		}
+		return undefined;
+	};
+	const addDate = (value: unknown): void => {
+		const normalized = normalizeDateValue(value);
+		if (normalized) exclusions.add(normalized);
+	};
+
+	addDate(nextScheduledDate);
+	addDate(task.googleCalendarExceptionOriginalScheduled);
+
+	if (Array.isArray(task.googleCalendarMovedOriginalDates)) {
+		for (const date of task.googleCalendarMovedOriginalDates) {
+			addDate(date);
+		}
+	}
+
+	// Calendar pipeline sometimes flattens these values into customProperties.
+	const customProperties = task.customProperties as Record<string, unknown> | undefined;
+	if (customProperties) {
+		addDate(customProperties.googleCalendarExceptionOriginalScheduled);
+		const movedDates = customProperties.googleCalendarMovedOriginalDates;
+		if (Array.isArray(movedDates)) {
+			for (const date of movedDates) {
+				addDate(date);
+			}
+		}
+	}
+
+	return exclusions;
+}
+
 /**
  * Generate recurring task instances for calendar display
  */
@@ -761,6 +890,10 @@ export function generateRecurringTaskInstances(
 	const hasOriginalTime = hasTimeComponent(task.scheduled);
 	const templateTime = getRecurringTime(task);
 	const nextScheduledDate = getDatePart(task.scheduled);
+	const recurringInstanceExclusions = buildRecurringInstanceExclusionSet(
+		task,
+		nextScheduledDate
+	);
 
 	// 1. Create next scheduled occurrence event
 	const scheduledTime = hasOriginalTime ? getTimePart(task.scheduled) : null;
@@ -802,8 +935,9 @@ export function generateRecurringTaskInstances(
 			continue;
 		}
 
-		// Skip if conflicts with next scheduled occurrence
-		if (instanceDate === nextScheduledDate) {
+		// Skip if this date is already represented by the concrete current occurrence
+		// or by known moved-occurrence exclusions.
+		if (recurringInstanceExclusions.has(instanceDate)) {
 			continue;
 		}
 

src/bases/helpers.ts

@@ -89,11 +89,16 @@ function createTaskInfoFromProperties(
 		"timeEstimate",
 		"completedDate",
 		"recurrence",
+		"recurrence_anchor",
 		"dateCreated",
 		"dateModified",
 		"timeEntries",
 		"reminders",
 		"icsEventId",
+		"googleCalendarEventId",
+		"googleCalendarExceptionEventId",
+		"googleCalendarExceptionOriginalScheduled",
+		"googleCalendarMovedOriginalDates",
 		"complete_instances",
 		"skipped_instances",
 		"blockedBy",
@@ -162,6 +167,11 @@ function createTaskInfoFromProperties(
 		totalTrackedTime: totalTrackedTime,
 		reminders: props.reminders,
 		icsEventId: props.icsEventId,
+		googleCalendarEventId: props.googleCalendarEventId,
+		googleCalendarExceptionEventId: props.googleCalendarExceptionEventId,
+		googleCalendarExceptionOriginalScheduled: props.googleCalendarExceptionOriginalScheduled,
+		googleCalendarMovedOriginalDates: props.googleCalendarMovedOriginalDates,
+		recurrence_anchor: props.recurrence_anchor,
 		complete_instances: props.complete_instances,
 		skipped_instances: props.skipped_instances,
 		blockedBy: props.blockedBy,

src/bootstrap/pluginBootstrap.ts

@@ -270,10 +270,11 @@ export function initializeServicesLazily(plugin: TaskNotesPlugin): void {
 
 			plugin.taskCalendarSyncService = new (await import("../services/TaskCalendarSyncService"))
 				.TaskCalendarSyncService(plugin, plugin.googleCalendarService);
+			plugin.taskCalendarSyncService.startDeletionQueueProcessor();
 
 			plugin.registerEvent(
 				plugin.emitter.on("file-deleted", (data: FileDeletedEventData) => {
-					if (!plugin.taskCalendarSyncService?.isEnabled()) {
+					if (!plugin.taskCalendarSyncService) {
 						return;
 					}
 

src/components/BatchContextMenu.ts

@@ -334,12 +334,16 @@ export class BatchContextMenu {
 					const file = plugin.app.vault.getAbstractFileByPath(path);
 					if (file) {
 						// Delete from Google Calendar before trashing file
-						if (plugin.taskCalendarSyncService?.isEnabled()) {
+						if (plugin.taskCalendarSyncService) {
 							const task = await plugin.cacheManager.getTaskInfo(path);
-							if (task?.googleCalendarEventId) {
+							if (task?.googleCalendarEventId || task?.googleCalendarExceptionEventId) {
 								try {
 									await plugin.taskCalendarSyncService
-										.deleteTaskFromCalendarByPath(path, task.googleCalendarEventId);
+										.deleteTaskFromCalendarByPath(
+											path,
+											task.googleCalendarEventId,
+											task.googleCalendarExceptionEventId
+										);
 								} catch (error) {
 									console.warn("Failed to delete task from Google Calendar:", error);
 								}

src/components/TaskContextMenu.ts

@@ -466,14 +466,22 @@ export class TaskContextMenu {
 						});
 						if (confirmed) {
 							// Delete from Google Calendar before trashing file
-							if (plugin.taskCalendarSyncService?.isEnabled() && task.googleCalendarEventId) {
-								plugin.taskCalendarSyncService
-									.deleteTaskFromCalendarByPath(task.path, task.googleCalendarEventId)
-									.catch((error) => {
-										console.warn("Failed to delete task from Google Calendar:", error);
-									});
+							if (
+								plugin.taskCalendarSyncService &&
+								(task.googleCalendarEventId || task.googleCalendarExceptionEventId)
+							) {
+								try {
+									await plugin.taskCalendarSyncService
+										.deleteTaskFromCalendarByPath(
+											task.path,
+											task.googleCalendarEventId,
+											task.googleCalendarExceptionEventId
+										);
+								} catch (error) {
+									console.warn("Failed to delete task from Google Calendar:", error);
+								}
 							}
-							plugin.app.vault.trash(file, true);
+							await plugin.app.vault.trash(file, true);
 						}
 					});
 				});

src/core/fieldMapping.ts

@@ -131,6 +131,32 @@ export function mapTaskFromFrontmatter(
 		mapped.googleCalendarEventId = frontmatter[mapping.googleCalendarEventId];
 	}
 
+	if (
+		mapping.googleCalendarExceptionEventId &&
+		frontmatter[mapping.googleCalendarExceptionEventId] !== undefined
+	) {
+		mapped.googleCalendarExceptionEventId =
+			frontmatter[mapping.googleCalendarExceptionEventId];
+	}
+
+	if (
+		mapping.googleCalendarExceptionOriginalScheduled &&
+		frontmatter[mapping.googleCalendarExceptionOriginalScheduled] !== undefined
+	) {
+		mapped.googleCalendarExceptionOriginalScheduled =
+			frontmatter[mapping.googleCalendarExceptionOriginalScheduled];
+	}
+
+	if (
+		mapping.googleCalendarMovedOriginalDates &&
+		frontmatter[mapping.googleCalendarMovedOriginalDates] !== undefined
+	) {
+		const movedDates = frontmatter[mapping.googleCalendarMovedOriginalDates];
+		mapped.googleCalendarMovedOriginalDates = Array.isArray(movedDates)
+			? movedDates
+			: [movedDates];
+	}
+
 	if (frontmatter[mapping.reminders] !== undefined) {
 		const reminders = frontmatter[mapping.reminders];
 		if (Array.isArray(reminders)) {
@@ -268,6 +294,25 @@ export function mapTaskToFrontmatter(
 		frontmatter[mapping.icsEventId] = taskData.icsEventId;
 	}
 
+	if (taskData.googleCalendarEventId !== undefined) {
+		frontmatter[mapping.googleCalendarEventId] = taskData.googleCalendarEventId;
+	}
+
+	if (taskData.googleCalendarExceptionEventId !== undefined) {
+		frontmatter[mapping.googleCalendarExceptionEventId] =
+			taskData.googleCalendarExceptionEventId;
+	}
+
+	if (taskData.googleCalendarExceptionOriginalScheduled !== undefined) {
+		frontmatter[mapping.googleCalendarExceptionOriginalScheduled] =
+			taskData.googleCalendarExceptionOriginalScheduled;
+	}
+
+	if (taskData.googleCalendarMovedOriginalDates !== undefined) {
+		frontmatter[mapping.googleCalendarMovedOriginalDates] =
+			taskData.googleCalendarMovedOriginalDates;
+	}
+
 	if (taskData.reminders !== undefined && taskData.reminders.length > 0) {
 		frontmatter[mapping.reminders] = taskData.reminders;
 	}

src/services/AutoArchiveService.ts

@@ -16,7 +16,7 @@ export class AutoArchiveService {
 	}
 
 	private hasGoogleCalendarLink(task: TaskInfo): boolean {
-		return !!task.googleCalendarEventId;
+		return !!(task.googleCalendarEventId || task.googleCalendarExceptionEventId);
 	}
 
 	private getCalendarCleanupState(): "ready" | "retry" | "skip" {

src/services/GoogleCalendarService.ts

@@ -602,6 +602,9 @@ export class GoogleCalendarService extends CalendarProvider {
 
 			// Build update payload
 			const payload: any = { ...currentEvent };
+			if (payload.status === "cancelled") {
+				payload.status = "confirmed";
+			}
 
 			// Support both 'title' and 'summary'
 			if (updates.title !== undefined || updates.summary !== undefined) {

src/services/MdbaseSpecService.ts

@@ -230,6 +230,14 @@ export class MdbaseSpecService {
 			items: { type: "string" },
 		});
 		this.addRoleField(lines, "googleCalendarEventId", { type: "string" });
+		this.addRoleField(lines, "googleCalendarExceptionEventId", { type: "string" });
+		this.addRoleField(lines, "googleCalendarExceptionOriginalScheduled", {
+			type: "string",
+		});
+		this.addRoleField(lines, "googleCalendarMovedOriginalDates", {
+			type: "list",
+			items: { type: "date" },
+		});
 
 		// User-defined fields
 		if (settings.userFields && settings.userFields.length > 0) {