fix(calendar): suppress duplicate projections of recorded recurrence moves

docs/releases/unreleased.md

@@ -16,6 +16,8 @@ Example:
 ```
 ## Fixed
 
+- Avoid showing a recurring task twice when its original occurrence date is recorded by a calendar move. Keep requested completion and skip history visible.
+
 - (#768) Fixed calendar view appearing empty in week and day views due to invalid time configuration values
   - Added time validation in settings UI with proper error messages and debouncing
   - Prevents "Cannot read properties of null (reading 'years')" error from FullCalendar

src/bases/calendar-core.ts

@@ -1141,6 +1141,13 @@ export function generateRecurringTaskInstances(
 	const hasOriginalTime = hasTimeComponent(task.scheduled);
 	const templateTime = getRecurringTime(task);
 	const nextScheduledDate = getDatePart(task.scheduled);
+	// A moved occurrence is represented at its current scheduled placement.
+	// Its original rule date must not also become a projected task. Recorded
+	// completions/skips are handled separately below and remain available.
+	const movedOriginalDates = new Set(task.googleCalendarMovedOriginalDates || []);
+	if (task.googleCalendarExceptionOriginalScheduled) {
+		movedOriginalDates.add(getDatePart(task.googleCalendarExceptionOriginalScheduled));
+	}
 	const spanDayOffset = showScheduledToDueSpan ? getScheduledToDueSpanDayOffset(task) : null;
 	const shouldCreateRecurringSpan = spanDayOffset !== null;
 	const recurringSearchStartDate = shouldCreateRecurringSpan
@@ -1227,7 +1234,7 @@ export function generateRecurringTaskInstances(
 			}
 
 			// Skip if conflicts with next scheduled occurrence
-			if (instanceDate === nextScheduledDate) {
+			if (instanceDate === nextScheduledDate || movedOriginalDates.has(instanceDate)) {
 				continue;
 			}
 

src/bases/calendarDataSignature.ts

@@ -18,6 +18,8 @@ const CALENDAR_DATA_SIGNATURE_FIELDS: FieldMappingKey[] = [
 	"blockedBy",
 	"icsEventId",
 	"googleCalendarEventId",
+	"googleCalendarExceptionOriginalScheduled",
+	"googleCalendarMovedOriginalDates",
 	"reminders",
 	"sortOrder",
 ];

src/bases/helpers.ts

@@ -198,6 +198,8 @@ function createTaskInfoFromProperties(
 		"icsEventId",
 		"complete_instances",
 		"skipped_instances",
+		"googleCalendarExceptionOriginalScheduled",
+		"googleCalendarMovedOriginalDates",
 		"blockedBy",
 		"blocking",
 		"sortOrder",
@@ -267,6 +269,10 @@ function createTaskInfoFromProperties(
 		icsEventId: toStringArray(props.icsEventId),
 		complete_instances: toStringArray(props.complete_instances),
 		skipped_instances: toStringArray(props.skipped_instances),
+		googleCalendarExceptionOriginalScheduled: toOptionalString(
+			props.googleCalendarExceptionOriginalScheduled
+		),
+		googleCalendarMovedOriginalDates: toStringArray(props.googleCalendarMovedOriginalDates),
 		blockedBy: toDependencies(props.blockedBy),
 		blocking: blockingTasks.length > 0 ? blockingTasks : undefined,
 		isBlocked: isBlocked,

tests/unit/bases/calendarDataSignature.test.ts

@@ -7,6 +7,16 @@ import {
 } from "../../../src/bases/calendarDataSignature";
 
 describe("calendarDataSignature", () => {
+	it("invalidates the calendar when mapped occurrence-move markers change", () => {
+		const properties = buildCalendarDataSignaturePropertyIds({
+			mapField: (field) => field === "googleCalendarExceptionOriginalScheduled" ? "originalOccurrence" : undefined,
+			showPropertyBasedEvents: false,
+		});
+		const before = [{path: "task.md", properties: {originalOccurrence: "2026-09-12"}}];
+		const after = [{path: "task.md", properties: {originalOccurrence: "2026-09-19"}}];
+		expect(buildCalendarDataSignature(before, properties)).not.toEqual(buildCalendarDataSignature(after, properties));
+		expect(properties).toContain("googleCalendarMovedOriginalDates");
+	});
 	it("selects mapped core fields, visible properties, and property-event fields", () => {
 		const propertyIds = buildCalendarDataSignaturePropertyIds({
 			mapField: (field) => (field === "scheduled" ? "planned" : undefined),

tests/unit/issues/issue-1603-recurring-calendar-instance-visibility.test.ts

@@ -14,6 +14,7 @@ import {
 } from "../../../src/bases/calendar-core";
 import type TaskNotesPlugin from "../../../src/main";
 import { TaskFactory } from "../../helpers/mock-factories";
+import { createTaskInfoFromBasesData } from "../../../src/bases/helpers";
 
 function createPlugin(): TaskNotesPlugin {
 	return {
@@ -35,6 +36,59 @@ describe("Issue #1603: recurring calendar instance visibility", () => {
 	const start = new Date("2026-02-01T00:00:00.000Z");
 	const end = new Date("2026-02-06T00:00:00.000Z");
 
+	it("renders a moved occurrence once and keeps later weekly occurrences", () => {
+		const task = TaskFactory.createRecurringTask("DTSTART:20260905;FREQ=WEEKLY;BYDAY=SA", {
+			scheduled: "2026-09-11",
+			googleCalendarExceptionOriginalScheduled: "2026-09-12",
+			googleCalendarMovedOriginalDates: ["2026-09-05"],
+		});
+		const before = JSON.stringify(task);
+		const events = generateRecurringTaskInstances(
+			task,
+			new Date("2026-09-01T00:00:00Z"),
+			new Date("2026-09-21T00:00:00Z"),
+			plugin
+		);
+		expect(getInstanceDates(events)).toEqual(["2026-09-11", "2026-09-19"]);
+		expect(JSON.stringify(task)).toBe(before);
+	});
+
+	it("preserves move markers through Bases conversion before the task cache is warm", () => {
+		const task = createTaskInfoFromBasesData({
+			path: "tasks/moved.md",
+			properties: {
+				recurrence: "DTSTART:20260905;FREQ=WEEKLY;BYDAY=SA",
+				scheduled: "2026-09-11",
+				googleCalendarExceptionOriginalScheduled: "2026-09-12",
+				googleCalendarMovedOriginalDates: ["2026-09-05"],
+			},
+		});
+		expect(task).not.toBeNull();
+		expect(getInstanceDates(generateRecurringTaskInstances(
+			task!, new Date("2026-09-01T00:00:00Z"), new Date("2026-09-21T00:00:00Z"), plugin
+		))).toEqual(["2026-09-11", "2026-09-19"]);
+	});
+
+	it("keeps recorded history for moved dates when history is requested", () => {
+		const task = TaskFactory.createRecurringTask("DTSTART:20260905;FREQ=WEEKLY;BYDAY=SA", {
+			scheduled: "2026-09-19",
+			googleCalendarMovedOriginalDates: ["2026-09-12"],
+			complete_instances: ["2026-09-12"],
+		});
+		const range = [new Date("2026-09-11T00:00:00Z"), new Date("2026-09-21T00:00:00Z")] as const;
+		expect(getInstanceDates(generateRecurringTaskInstances(task, ...range, plugin))).toEqual([
+			"2026-09-12",
+			"2026-09-19",
+		]);
+		expect(
+			getInstanceDates(
+				generateRecurringTaskInstances(task, ...range, plugin, {
+					showCompletedRecurringInstances: false,
+				})
+			)
+		).toEqual(["2026-09-19"]);
+	});
+
 	it("keeps completed and skipped recurring instances visible by default", () => {
 		const task = TaskFactory.createRecurringTask("FREQ=DAILY;INTERVAL=1", {
 			path: "tasks/recur.md",