Table of Contents

Model weekly local-time availability

WeeklySchedule answers a focused question: is this recurring weekly schedule active at a local day and time, or at a specific instant in its IANA time zone?

It is useful for opening hours and recurring availability. It is not a holiday calendar, capacity model, recurrence engine, or elapsed-duration scheduler.

dotnet add package Trellis.Primitives

Create overnight and all-day periods

This complete console example creates Friday overnight hours plus an all-day Sunday:

using Trellis;
using Trellis.Primitives;

var scheduleResult = StoreHours.Create();

if (!scheduleResult.TryGetValue(out var schedule, out var error))
{
    Console.Error.WriteLine(error);
    return;
}

var instant = new DateTimeOffset(
    2026, 9, 26, 8, 0, 0, TimeSpan.Zero);

Console.WriteLine(schedule.IsActiveAt(instant));

public static class StoreHours
{
    public static Result<WeeklySchedule> Create() =>
        WeeklyPeriod.TryCreate(
                DayOfWeek.Friday,
                new TimeOnly(22, 0),
                new TimeOnly(2, 0),
                "friday")
            .Bind(friday =>
                WeeklyPeriod.TryCreateAllDay(DayOfWeek.Sunday, "sunday")
                    .Bind(sunday =>
                        WeeklySchedule.TryCreate(
                            "America/Los_Angeles",
                            [friday, sunday],
                            "hours")));
}

A normal period includes its start and excludes its end. An end earlier than the start crosses midnight, so Friday 22:00 to 02:00 includes early Saturday morning.

Equal endpoints do not mean all day. Use TryCreateAllDay to state that intent explicitly.

Let the schedule validate the week

WeeklySchedule.TryCreate copies and sorts the periods, rejects overlaps across day and week boundaries, and permits periods that only touch. An empty period list means always closed.

The time-zone identifier must resolve to an IANA zone. UTC is valid; Windows-only identifiers are rejected. IsActiveAt converts the supplied instant with the schedule's retained zone rules, so repeated and skipped local times follow daylight-saving behavior.

Use Contains(day, time) when you already have local weekly clock coordinates. Use IsActiveAt(instant) when you have an absolute instant.

Keep transport and persistence explicit

Project schedules through an application-owned DTO containing the zone ID and each period's day, start, end, and all-day flag. Rebuild the value through TryCreate methods at the boundary.

Do not apply the composite value-object JSON converter to these types; collections and TimeOnly are outside that converter's shape. They also do not expose parameterless constructors for direct EF owned-type materialization. Choose an explicit JSON snapshot or separate persistence records and rehydrate through the factories.

Complete generated API:

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