Accept minute-precision times when adding DTSTART

src/recurrence.ts

@@ -9,6 +9,7 @@ import {
 	hasTimeComponent,
 	parseDateToLocal,
 	parseDateToUTC,
+	resolveDateTimeRangeBound,
 } from "./date";
 import type { RecurrenceAnchor, TaskInfo } from "./types";
 
@@ -452,7 +453,8 @@ function getLookAheadDays(recurrence: string): number {
 
 function formatDtstartValue(dateStr: string): string {
 	if (hasTimeComponent(dateStr)) {
-		const dateTime = parseDateToLocal(dateStr);
+		// Task dates are often minute precision ("2026-06-04T10:30"), which the strict parser rejects.
+		const dateTime = resolveDateTimeRangeBound(dateStr, "from");
 		const year = dateTime.getFullYear();
 		const month = String(dateTime.getMonth() + 1).padStart(2, "0");
 		const day = String(dateTime.getDate()).padStart(2, "0");

test/recurrence.test.mjs

@@ -41,3 +41,48 @@ test("advances date-only due offset for recurring tasks with timed scheduled dat
 		due: "2026-06-06",
 	});
 });
+
+test("adds DTSTART for a minute-precision scheduled time (tasknotes#2328)", async () => {
+	const { addDTSTARTToRecurrenceRule, updateDTSTARTInRecurrenceRule } = await import(
+		"../dist/esm/recurrence.js"
+	);
+	const withSeconds = addDTSTARTToRecurrenceRule({
+		recurrence: "FREQ=DAILY",
+		scheduled: "2026-06-04T10:30:00",
+	});
+	assert.equal(
+		addDTSTARTToRecurrenceRule({ recurrence: "FREQ=DAILY", scheduled: "2026-06-04T10:30" }),
+		withSeconds
+	);
+	assert.equal(updateDTSTARTInRecurrenceRule("FREQ=DAILY", "2026-06-04T10:30"), withSeconds);
+	assert.match(withSeconds, /^DTSTART:20260604T103000Z;FREQ=DAILY$/);
+});
+
+test("completing a materialized occurrence of a timed parent advances it (tasknotes#2328)", async () => {
+	const { buildMaterializedOccurrenceCompletePlan } = await import("../dist/esm/operations.js");
+	const plan = buildMaterializedOccurrenceCompletePlan({
+		occurrenceTask: {
+			path: "Tasks/Standup 2026-06-04.md",
+			title: "Standup",
+			status: "open",
+			recurrence_parent: "[[Tasks/Standup]]",
+			occurrence_date: "2026-06-04",
+			scheduled: "2026-06-04T10:30",
+		},
+		parentTask: {
+			path: "Tasks/Standup.md",
+			title: "Standup",
+			status: "open",
+			recurrence: "FREQ=DAILY",
+			scheduled: "2026-06-04T10:30",
+			complete_instances: [],
+			skipped_instances: [],
+		},
+		completedStatus: "done",
+		currentTimestamp: "2026-06-04T11:00:00.000Z",
+		completionDate: "2026-06-04",
+		maintainDueDateOffsetInRecurring: true,
+	});
+	assert.deepEqual(plan.parentUpdates.complete_instances, ["2026-06-04"]);
+	assert.equal(plan.parentUpdates.scheduled, "2026-06-05T10:30");
+});