fix: anchor task timeblocks to scheduled date

src/components/TaskContextMenu.ts

@@ -1,7 +1,7 @@
 import { Menu, Notice, TFile } from "obsidian";
 import TaskNotesPlugin from "../main";
 import { TaskDependency, TaskInfo } from "../types";
-import { formatDateForStorage, parseDateToLocal } from "../utils/dateUtils";
+import { formatDateForStorage } from "../utils/dateUtils";
 import { ReminderModal } from "../modals/ReminderModal";
 import { CalendarExportService } from "../services/CalendarExportService";
 import { showConfirmationModal } from "../modals/ConfirmationModal";
@@ -18,6 +18,7 @@ import {
 } from "../utils/dependencyUtils";
 import { generateLink } from "../utils/linkUtils";
 import { ContextMenu } from "./ContextMenu";
+import { buildTimeblockPrefillForTask } from "../utils/timeblockPrefillUtils";
 import { TimeblockCreationModal } from "../modals/TimeblockCreationModal";
 
 export interface TaskContextMenuOptions {
@@ -42,49 +43,6 @@ export class TaskContextMenu {
 		return this.options.plugin.i18n.translate(key, params);
 	}
 
-	private formatTimeForInput(date: Date): string {
-		const hours = String(date.getHours()).padStart(2, "0");
-		const minutes = String(date.getMinutes()).padStart(2, "0");
-		return `${hours}:${minutes}`;
-	}
-
-	private getTimeblockPrefillForTask(task: TaskInfo): {
-		date: string;
-		startTime: string;
-		endTime: string;
-	} {
-		let startDate = new Date(this.options.targetDate);
-
-		// If the task has a scheduled datetime, use it as the timeblock anchor.
-		if (task.scheduled && task.scheduled.includes("T")) {
-			try {
-				startDate = parseDateToLocal(task.scheduled);
-			} catch {
-				// Fallback to target date defaults if parsing fails.
-			}
-		}
-
-		if (isNaN(startDate.getTime())) {
-			startDate = new Date();
-		}
-
-		// For date-only tasks, default to a 09:00 planning slot.
-		if (!task.scheduled || !task.scheduled.includes("T")) {
-			startDate.setHours(9, 0, 0, 0);
-		}
-
-		const durationMinutes = task.timeEstimate && task.timeEstimate > 0
-			? task.timeEstimate
-			: 60;
-		const endDate = new Date(startDate.getTime() + durationMinutes * 60 * 1000);
-
-		return {
-			date: formatDateForStorage(startDate),
-			startTime: this.formatTimeForInput(startDate),
-			endTime: this.formatTimeForInput(endDate),
-		};
-	}
-
 	private buildMenu(): void {
 		const { task, plugin } = this.options;
 
@@ -362,7 +320,7 @@ export class TaskContextMenu {
 				item.setTitle("Create timeblock");
 				item.setIcon("calendar-plus");
 				item.onClick(() => {
-					const prefill = this.getTimeblockPrefillForTask(task);
+					const prefill = buildTimeblockPrefillForTask(task, this.options.targetDate);
 					const modal = new TimeblockCreationModal(plugin.app, plugin, {
 						date: prefill.date,
 						startTime: prefill.startTime,

src/utils/timeblockPrefillUtils.ts

@@ -0,0 +1,54 @@
+import { TaskInfo } from "../types";
+import {
+	formatDateForStorage,
+	hasTimeComponent,
+	parseDateToLocal,
+} from "./dateUtils";
+
+export interface TimeblockPrefill {
+	date: string;
+	startTime: string;
+	endTime: string;
+}
+
+function formatTimeForInput(date: Date): string {
+	const hours = String(date.getHours()).padStart(2, "0");
+	const minutes = String(date.getMinutes()).padStart(2, "0");
+	return `${hours}:${minutes}`;
+}
+
+export function buildTimeblockPrefillForTask(
+	task: TaskInfo,
+	targetDate: Date
+): TimeblockPrefill {
+	let startDate: Date | null = null;
+
+	if (task.scheduled) {
+		try {
+			startDate = parseDateToLocal(task.scheduled);
+		} catch {
+			startDate = null;
+		}
+	}
+
+	if (!startDate || isNaN(startDate.getTime())) {
+		startDate = new Date(targetDate);
+	}
+
+	if (isNaN(startDate.getTime())) {
+		startDate = new Date();
+	}
+
+	if (!task.scheduled || !hasTimeComponent(task.scheduled)) {
+		startDate.setHours(9, 0, 0, 0);
+	}
+
+	const durationMinutes = task.timeEstimate && task.timeEstimate > 0 ? task.timeEstimate : 60;
+	const endDate = new Date(startDate.getTime() + durationMinutes * 60 * 1000);
+
+	return {
+		date: formatDateForStorage(startDate),
+		startTime: formatTimeForInput(startDate),
+		endTime: formatTimeForInput(endDate),
+	};
+}

tests/unit/utils/timeblockPrefillUtils.test.ts

@@ -0,0 +1,67 @@
+import { describe, expect, it } from "@jest/globals";
+
+import { TaskInfo } from "../../../src/types";
+import {
+	formatDateForStorage,
+	parseDateToLocal,
+} from "../../../src/utils/dateUtils";
+import { buildTimeblockPrefillForTask } from "../../../src/utils/timeblockPrefillUtils";
+
+function makeTask(overrides: Partial<TaskInfo> = {}): TaskInfo {
+	return {
+		path: "TaskNotes/Tasks/example.md",
+		title: "Example task",
+		status: "open",
+		priority: "normal",
+		...overrides,
+	};
+}
+
+describe("buildTimeblockPrefillForTask", () => {
+	it("uses the scheduled date for date-only scheduled tasks", () => {
+		const prefill = buildTimeblockPrefillForTask(
+			makeTask({
+				scheduled: "2026-03-10",
+				timeEstimate: 30,
+			}),
+			new Date(2026, 2, 29, 12, 0, 0, 0)
+		);
+
+		expect(prefill).toEqual({
+			date: formatDateForStorage(parseDateToLocal("2026-03-10")),
+			startTime: "09:00",
+			endTime: "09:30",
+		});
+	});
+
+	it("uses the scheduled datetime for time-aware scheduled tasks", () => {
+		const prefill = buildTimeblockPrefillForTask(
+			makeTask({
+				scheduled: "2026-03-10T14:15",
+				timeEstimate: 45,
+			}),
+			new Date(2026, 2, 29, 12, 0, 0, 0)
+		);
+
+		expect(prefill).toEqual({
+			date: formatDateForStorage(parseDateToLocal("2026-03-10T14:15")),
+			startTime: "14:15",
+			endTime: "15:00",
+		});
+	});
+
+	it("falls back to the target date for unscheduled tasks", () => {
+		const prefill = buildTimeblockPrefillForTask(
+			makeTask(),
+			new Date(2026, 2, 29, 12, 0, 0, 0)
+		);
+		const expectedFallbackDate = new Date(2026, 2, 29, 12, 0, 0, 0);
+		expectedFallbackDate.setHours(9, 0, 0, 0);
+
+		expect(prefill).toEqual({
+			date: formatDateForStorage(expectedFallbackDate),
+			startTime: "09:00",
+			endTime: "10:00",
+		});
+	});
+});