feat(locations): manage ordered site contacts

Api.SeaHavenIndustries.Tests/LocationSiteContactsTests.cs

@@ -0,0 +1,581 @@
+using System.Security.Claims;
+using System.Text.Json;
+using Api.SeaHavenIndustries.Controllers;
+using Data.SeaHavenIndustries;
+using FluentAssertions;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Migrations.Operations;
+using Microsoft.Extensions.Logging;
+using Moq;
+using SeaHaven.DataServices.Implementation;
+using SeaHaven.DataServices.Interfaces;
+using SeaHaven.Services.DTOs;
+using SeaHaven.Services.Helpers;
+using SeaHaven.Services.Implementation;
+using SeaHaven.Services.Validation;
+using Xunit;
+
+namespace Api.SeaHavenIndustries.Tests;
+
+public class LocationSiteContactsTests
+{
+    private static ApplicationDbContext NewContext()
+    {
+        var options = new DbContextOptionsBuilder<ApplicationDbContext>()
+            .UseInMemoryDatabase(Guid.NewGuid().ToString())
+            .Options;
+        return new ApplicationDbContext(options);
+    }
+
+    private static LocationService NewService(ApplicationDbContext ctx) =>
+        new(
+            new LocationDataService(ctx),
+            new AccountDataService(ctx),
+            new CreateLocationValidation(),
+            new UpdateLocationValidation());
+
+    private static ClaimsPrincipal OrgWideAdmin()
+    {
+        var claims = new List<Claim>
+        {
+            new(ClaimTypes.NameIdentifier, "admin-1"),
+            new(ClaimTypes.Role, "Admin"),
+            new(SeaHavenClaimTypes.OrgScope, SeaHavenClaimTypes.OrgScopeAll)
+        };
+        return new ClaimsPrincipal(new ClaimsIdentity(claims, "test"));
+    }
+
+    private static async Task<Locations> SeedLocationWithContactsAsync(ApplicationDbContext ctx)
+    {
+        var service = NewService(ctx);
+        await service.CreateLocationFromRequestAsync(new LocationCreateRequestDTO
+        {
+            Name = "Depot",
+            AccountId = null,
+            Contacts = new List<SiteContactRequestDTO>
+            {
+                new() { Name = " Alice Cooper ", Phone = " 555-0100 " },
+                new() { Name = "Bob Dillon", Phone = "555-0200"}
+            }
+        }, OrgWideAdmin(), CancellationToken.None);
+        return ctx.Locations.Include(l => l.Contacts).Single();
+    }
+
+    [Fact]
+    public async Task Create_WithContacts_PersistsTrimmedOrderedRows_MirrorsFirstPhone_SetsAccountFromLocation()
+    {
+        using var ctx = NewContext();
+        ctx.Accounts.Add(new Accounts { Id = 7, Name = "Customer", IsDeleted = false });
+        await ctx.SaveChangesAsync();
+
+        await NewService(ctx).CreateLocationFromRequestAsync(new LocationCreateRequestDTO
+        {
+            Name = "Warehouse",
+            AccountId = 7,
+            Contacts = new List<SiteContactRequestDTO>
+            {
+                new() { Name = " Alice Cooper ", Phone = " 555-0100 " },
+                new() { Name = "Bob Dillon", Phone = "555-0200" }
+            }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        var location = ctx.Locations.Include(l => l.Contacts).Single();
+        location.PhoneNumber.Should().Be("555-0100", "first contact mirrors Location.PhoneNumber");
+
+        var contacts = location.Contacts.OrderBy(c => c.SiteContactOrder).ToList();
+        contacts.Should().HaveCount(2);
+        contacts[0].FirstName.Should().Be("Alice Cooper");
+        contacts[0].MiddleName.Should().BeNull();
+        contacts[0].LastName.Should().BeNull();
+        contacts[0].PhoneNumber.Should().Be("555-0100");
+        contacts[0].SiteContactOrder.Should().Be(0);
+        contacts[0].AccountId.Should().Be(7, "AccountId must come from the location");
+        contacts[0].LocationId.Should().Be(location.Id);
+        contacts[0].createdby.Should().Be("admin-1");
+        contacts[0].CreatedDate.Should().NotBeNull();
+        contacts[1].SiteContactOrder.Should().Be(1);
+    }
+
+    [Fact]
+    public async Task Create_EmptyContactsArray_IsExplicitValidationError_AndWritesNothing()
+    {
+        using var ctx = NewContext();
+
+        var act = () => NewService(ctx).CreateLocationFromRequestAsync(new LocationCreateRequestDTO
+        {
+            Name = "Warehouse",
+            Contacts = new List<SiteContactRequestDTO>()
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        (await act.Should().ThrowAsync<FluentValidation.ValidationException>())
+            .Which.Errors.Should().ContainSingle(e => e.PropertyName == "Contacts");
+        ctx.Locations.Should().BeEmpty();
+        ctx.Contacts.Should().BeEmpty();
+    }
+
+    [Theory]
+    [InlineData(null, "555-0100", "Contact name is required.")]
+    [InlineData("   ", "555-0100", "Contact name is required.")]
+    [InlineData("Alice", null, "Contact phone is required.")]
+    [InlineData("Alice", "  ", "Contact phone is required.")]
+    [InlineData("Alice", "555-0100", null)]
+    public async Task Create_ValidatesEachRow(string? name, string? phone, string? expectedError)
+    {
+        using var ctx = NewContext();
+        var contacts = new List<SiteContactRequestDTO> { new() { Name = name, Phone = phone } };
+
+        var act = () => NewService(ctx).CreateLocationFromRequestAsync(new LocationCreateRequestDTO
+        {
+            Name = "Warehouse",
+            Contacts = contacts
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        if (expectedError == null)
+        {
+            await act.Should().NotThrowAsync();
+            return;
+        }
+
+        (await act.Should().ThrowAsync<FluentValidation.ValidationException>())
+            .Which.Errors.Should().Contain(e => e.ErrorMessage == expectedError);
+    }
+
+    [Fact]
+    public async Task Create_RejectsOversizedNameAndPhone()
+    {
+        using var ctx = NewContext();
+
+        var act = () => NewService(ctx).CreateLocationFromRequestAsync(new LocationCreateRequestDTO
+        {
+            Name = "Warehouse",
+            Contacts = new List<SiteContactRequestDTO>
+            {
+                new() { Name = new string('x', 101), Phone = new string('5', 21) }
+            }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        var thrown = (await act.Should().ThrowAsync<FluentValidation.ValidationException>()).Which;
+        thrown.Errors.Should().Contain(e => e.ErrorMessage.Contains("cannot exceed 100"));
+        thrown.Errors.Should().Contain(e => e.ErrorMessage.Contains("cannot exceed 20"));
+    }
+
+    [Fact]
+    public async Task Create_RejectsMoreThanTwentyContacts()
+    {
+        using var ctx = NewContext();
+        var contacts = Enumerable.Range(1, 21)
+            .Select(i => new SiteContactRequestDTO { Name = $"C{i}", Phone = "555-0100" })
+            .ToList();
+
+        var act = () => NewService(ctx).CreateLocationFromRequestAsync(new LocationCreateRequestDTO
+        {
+            Name = "Warehouse",
+            Contacts = contacts
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        (await act.Should().ThrowAsync<FluentValidation.ValidationException>())
+            .Which.Errors.Should().ContainSingle(e => e.ErrorMessage.Contains("cannot exceed 20"));
+    }
+
+    [Fact]
+    public async Task Update_ContactsNull_KeepsLegacyBehavior_AndDoesNotMutateContactRows()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        var before = ctx.Contacts.AsNoTracking().OrderBy(c => c.Id).ToList();
+
+        await NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Phone = "555-9999"
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        var after = ctx.Contacts.AsNoTracking().OrderBy(c => c.Id).ToList();
+        after.Should().HaveCount(before.Count);
+        after[0].FirstName.Should().Be(before[0].FirstName);
+        after[0].PhoneNumber.Should().Be(before[0].PhoneNumber);
+        after[0].SiteContactOrder.Should().Be(before[0].SiteContactOrder);
+        after[0].IsDeleted.Should().Be(before[0].IsDeleted);
+        ctx.Locations.Single().PhoneNumber.Should().Be("555-9999", "legacy updates keep request.Phone");
+    }
+
+    [Fact]
+    public async Task Update_EmptyContactsArray_IsExplicitValidationError()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+
+        var act = () => NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO>()
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        (await act.Should().ThrowAsync<FluentValidation.ValidationException>())
+            .Which.Errors.Should().ContainSingle(e => e.PropertyName == "Contacts");
+        ctx.Contacts.Should().OnlyContain(c => c.IsDeleted != true);
+    }
+
+    [Fact]
+    public async Task Update_ReordersAndSoftDeletes_DensifiesOrder_AndUpdatesMirror()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        var alice = seeded.Contacts.Single(c => c.FirstName == "Alice Cooper");
+        var bob = seeded.Contacts.Single(c => c.FirstName == "Bob Dillon");
+
+        await NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO>
+            {
+                new() { Id = bob.Id, Name = "Bob Dillon", Phone = "555-0200" },
+                new() { Id = alice.Id, Name = "Alice Cooper", Phone = "555-0300" },
+                new() { Name = "Cara Lane", Phone = "555-0400" }
+            }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        var location = ctx.Locations.Include(l => l.Contacts).Single();
+        location.PhoneNumber.Should().Be("555-0200", "reorder must update the mirror to the new first contact");
+
+        var active = location.Contacts.Where(c => c.IsDeleted != true).OrderBy(c => c.SiteContactOrder).ToList();
+        active.Should().HaveCount(3);
+        active.Select(c => c.FirstName).Should().ContainInOrder("Bob Dillon", "Alice Cooper", "Cara Lane");
+        active.Select(c => c.SiteContactOrder).Should().ContainInOrder(new int?[] { 0, 1, 2 }, "order is densified from zero");
+        active[1].PhoneNumber.Should().Be("555-0300");
+        active[0].Id.Should().Be(bob.Id);
+        active[1].Id.Should().Be(alice.Id, "existing ids are preserved");
+        active[2].AccountId.Should().Be(location.AccountId);
+    }
+
+    [Fact]
+    public async Task Update_SoftDeletesRemovedContacts_WithAuditFields_KeepingRowsReadable()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        var alice = seeded.Contacts.Single(c => c.FirstName == "Alice Cooper");
+        var bob = seeded.Contacts.Single(c => c.FirstName == "Bob Dillon");
+
+        await NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO> { new() { Id = alice.Id, Name = "Alice Cooper", Phone = "555-0100" } }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        var removed = ctx.Contacts.AsNoTracking().Single(c => c.Id == bob.Id);
+        removed.IsDeleted.Should().BeTrue();
+        removed.DeleterUserId.Should().Be("admin-1");
+        removed.DeletionTime.Should().NotBeNull();
+        removed.LastModificationTime.Should().NotBeNull();
+        removed.FirstName.Should().Be("Bob Dillon", "soft deleted rows keep data so historical WorkOrderContacts still render");
+        removed.PhoneNumber.Should().Be("555-0200");
+
+        var kept = ctx.Contacts.AsNoTracking().Single(c => c.Id == alice.Id);
+        kept.IsDeleted.Should().NotBeTrue();
+    }
+
+    [Fact]
+    public async Task Update_ForeignLocationContactId_RejectedWithoutMutation()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        ctx.Locations.Add(new Locations { Id = seeded.Id + 1, Name = "Other" });
+        ctx.Contacts.Add(new Contacts { Id = 901, LocationId = seeded.Id + 1, FirstName = "Foreign", PhoneNumber = "555-0900" });
+        await ctx.SaveChangesAsync();
+        var snapshot = ctx.Contacts.AsNoTracking().OrderBy(c => c.Id).ToList();
+
+        var act = () => NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO>
+            {
+                new() { Name = "Alice Cooper", Phone = "555-0100" },
+                new() { Id = 901, Name = "Foreign", Phone = "555-0900" }
+            }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        (await act.Should().ThrowAsync<FluentValidation.ValidationException>())
+            .Which.Errors.Should().ContainSingle(e => e.PropertyName.Contains("Id"));
+
+        var after = ctx.Contacts.AsNoTracking().OrderBy(c => c.Id).ToList();
+        after.Should().HaveCount(snapshot.Count);
+        after.Should().BeEquivalentTo(snapshot, o => o.Excluding(c => c.Location));
+        ctx.Locations.AsNoTracking().Single(l => l.Id == seeded.Id).PhoneNumber
+            .Should().Be("555-0100", "the rejected update must not persist any change");
+    }
+
+    [Fact]
+    public async Task Update_DeletedContactId_Rejected()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        var bob = seeded.Contacts.Single(c => c.FirstName == "Bob Dillon");
+        bob.IsDeleted = true;
+        await ctx.SaveChangesAsync();
+
+        var act = () => NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO> { new() { Id = bob.Id, Name = "Bob Dillon", Phone = "555-0200" } }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        (await act.Should().ThrowAsync<FluentValidation.ValidationException>())
+            .Which.Errors.Should().ContainSingle(e => e.PropertyName.Contains("Id"));
+    }
+
+    [Fact]
+    public async Task Update_AccountLevelContactId_Rejected()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        ctx.Contacts.Add(new Contacts { Id = 902, AccountId = 55, LocationId = null, FirstName = "AccountOnly", PhoneNumber = "555-0900" });
+        await ctx.SaveChangesAsync();
+
+        var act = () => NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO> { new() { Id = 902, Name = "AccountOnly", Phone = "555-0900" } }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        (await act.Should().ThrowAsync<FluentValidation.ValidationException>())
+            .Which.Errors.Should().ContainSingle(e => e.PropertyName.Contains("Id"));
+    }
+
+    [Fact]
+    public async Task Update_DuplicateContactIds_Rejected()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        var alice = seeded.Contacts.Single(c => c.FirstName == "Alice Cooper");
+
+        var act = () => NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO>
+            {
+                new() { Id = alice.Id, Name = "Alice Cooper", Phone = "555-0100" },
+                new() { Id = alice.Id, Name = "Alice Cooper", Phone = "555-0100" }
+            }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        (await act.Should().ThrowAsync<FluentValidation.ValidationException>())
+            .Which.Errors.Should().ContainSingle(e => e.ErrorMessage.Contains("more than once"));
+    }
+
+    [Fact]
+    public async Task Update_AccountScopedCaller_CannotAttachContactsToForeignLocation()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        seeded.AccountId = 99;
+        await ctx.SaveChangesAsync();
+
+        var claims = new List<Claim>
+        {
+            new(ClaimTypes.NameIdentifier, "actor-1"),
+            new(ClaimTypes.Role, "Dispatcher"),
+            new(SeaHavenClaimTypes.AccountId, "4")
+        };
+        var caller = new ClaimsPrincipal(new ClaimsIdentity(claims, "test"));
+
+        var act = () => NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO> { new() { Name = "Nope", Phone = "555-0000" } }
+        }, caller, CancellationToken.None);
+
+        await act.Should().ThrowAsync<UnauthorizedAccessException>();
+        ctx.Contacts.Should().OnlyContain(c => c.IsDeleted != true);
+    }
+
+    [Fact]
+    public async Task Detail_ExcludesDeletedContacts_AndOrdersBySiteContactOrderThenId()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        var alice = seeded.Contacts.Single(c => c.FirstName == "Alice Cooper");
+        var bob = seeded.Contacts.Single(c => c.FirstName == "Bob Dillon");
+
+        await NewService(ctx).UpdateLocationFromRequestAsync(seeded.Id, new LocationUpdateRequestDTO
+        {
+            Name = "Depot",
+            Contacts = new List<SiteContactRequestDTO> { new() { Id = alice.Id, Name = "Alice Cooper", Phone = "555-0100" } }
+        }, OrgWideAdmin(), CancellationToken.None);
+
+        var detail = await NewService(ctx).GetLocationDetailAsync(seeded.Id, CancellationToken.None);
+
+        detail!.Contacts.Should().ContainSingle().Which.Id.Should().Be(alice.Id);
+    }
+
+    [Fact]
+    public async Task Detail_OrdersContactsByOrderThenId_WhenOrdersAreMissing()
+    {
+        using var ctx = NewContext();
+        var loc = new Locations { Id = 5, Name = "Legacy", AccountId = 7 };
+        ctx.Locations.Add(loc);
+        ctx.Contacts.AddRange(
+            new Contacts { Id = 31, LocationId = 5, AccountId = 7, FirstName = "No Order B", PhoneNumber = "555-2" },
+            new Contacts { Id = 30, LocationId = 5, AccountId = 7, FirstName = "No Order A", PhoneNumber = "555-1" });
+        await ctx.SaveChangesAsync();
+
+        var detail = await NewService(ctx).GetLocationDetailAsync(5, CancellationToken.None);
+
+        detail!.Contacts!.Select(c => c.Name).Should().ContainInOrder("No Order A", "No Order B");
+    }
+
+    [Fact]
+    public async Task List_LoadsPageContactsInSingleBatchedRead()
+    {
+        var data = new Mock<ILocationDataService>();
+        data.Setup(d => d.GetListPagedAsync(It.IsAny<int>(), It.IsAny<int>(), It.IsAny<string?>(), It.IsAny<IReadOnlyCollection<string>?>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync((new List<Locations>
+            {
+                new() { Id = 1, Name = "One" },
+                new() { Id = 2, Name = "Two" }
+            }, 2));
+        data.Setup(d => d.GetSiteContactsByLocationIdsAsync(It.IsAny<IReadOnlyCollection<int>>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<Contacts>
+            {
+                new() { Id = 10, LocationId = 1, SiteContactOrder = 1, FirstName = "Second", PhoneNumber = "555-2" },
+                new() { Id = 11, LocationId = 1, SiteContactOrder = 0, FirstName = "First", PhoneNumber = "555-1" },
+                new() { Id = 12, LocationId = 2, SiteContactOrder = 0, FirstName = "Solo", PhoneNumber = "555-3" }
+            });
+
+        var service = new LocationService(
+            data.Object,
+            Mock.Of<IAccountDataService>(),
+            new CreateLocationValidation(),
+            new UpdateLocationValidation());
+
+        var page = await service.GetLocationListPagedAsync(1, 10, null, cancellationToken: CancellationToken.None);
+
+        page.Items.Should().HaveCount(2);
+        page.Items.Single(i => i.Id == 1).Contacts!.Select(c => c.Name)
+            .Should().ContainInOrder(new[] { "First", "Second" }, "contacts are ordered per location");
+        page.Items.Single(i => i.Id == 2).Contacts!.Select(c => c.Name).Should().ContainSingle("Solo");
+        data.Verify(d => d.GetSiteContactsByLocationIdsAsync(It.IsAny<IReadOnlyCollection<int>>(), It.IsAny<CancellationToken>()), Times.Once);
+        data.Verify(d => d.GetSiteContactsByLocationIdsAsync(It.Is<IReadOnlyCollection<int>>(ids => ids.Contains(1) && ids.Contains(2)), It.IsAny<CancellationToken>()), Times.Once);
+    }
+
+    [Fact]
+    public async Task DataService_GetSiteContactsByLocationIdsAsync_ExcludesDeleted_AndOrders()
+    {
+        using var ctx = NewContext();
+        ctx.Contacts.AddRange(
+            new Contacts { Id = 1, LocationId = 5, SiteContactOrder = 1, FirstName = "B" },
+            new Contacts { Id = 2, LocationId = 5, SiteContactOrder = 0, FirstName = "A" },
+            new Contacts { Id = 3, LocationId = 5, SiteContactOrder = 0, FirstName = "Tie", IsDeleted = true },
+            new Contacts { Id = 4, LocationId = 6, SiteContactOrder = 0, FirstName = "Other" });
+        await ctx.SaveChangesAsync();
+
+        var rows = await new LocationDataService(ctx).GetSiteContactsByLocationIdsAsync(new[] { 5 }, CancellationToken.None);
+
+        rows.Select(r => r.FirstName).Should().ContainInOrder("A", "B");
+        rows.Should().OnlyContain(r => r.IsDeleted != true);
+    }
+
+    [Fact]
+    public async Task DataService_GetSiteContactsByLocationIdsAsync_EmptyInput_ReturnsWithoutQuerying()
+    {
+        using var ctx = NewContext();
+        ctx.Contacts.Add(new Contacts { Id = 1, LocationId = 5, FirstName = "A" });
+        await ctx.SaveChangesAsync();
+
+        var rows = await new LocationDataService(ctx).GetSiteContactsByLocationIdsAsync(Array.Empty<int>(), CancellationToken.None);
+
+        rows.Should().BeEmpty();
+    }
+
+    private sealed class ExposedSH138Migration : Data.SeaHavenIndustries.Migrations.SH138_SiteContacts
+    {
+        public void UpExposed(MigrationBuilder builder) => Up(builder);
+        public void DownExposed(MigrationBuilder builder) => Down(builder);
+    }
+
+    [Fact]
+    public void Migration_SH138_IsAdditiveOnly()
+    {
+        var migration = new ExposedSH138Migration();
+
+        var up = new MigrationBuilder("SqlServer");
+        migration.UpExposed(up);
+
+        up.Operations.Should().ContainSingle("the migration must only add the SiteContactOrder column");
+        var column = up.Operations.Single().Should().BeOfType<AddColumnOperation>().Subject;
+        column.Table.Should().Be("Contacts");
+        column.Name.Should().Be("SiteContactOrder");
+        column.IsNullable.Should().BeTrue("existing rows and legacy contacts have no order");
+        column.ClrType.Should().Be(typeof(int));
+
+        var down = new MigrationBuilder("SqlServer");
+        migration.DownExposed(down);
+
+        down.Operations.Should().ContainSingle("reverting drops only the added column");
+        down.Operations.Single().Should().BeOfType<DropColumnOperation>();
+    }
+
+    [Fact]
+    public void Migration_SH138_HasNoReorderIndexOrFkChange()
+    {
+        var migration = new ExposedSH138Migration();
+        var up = new MigrationBuilder("SqlServer");
+        migration.UpExposed(up);
+
+        up.Operations.Should().NotContain(o => o is CreateIndexOperation, "no unique reorder index");
+        up.Operations.Should().NotContain(o => o is AddForeignKeyOperation || o is DropForeignKeyOperation, "the existing restrict relationship is unchanged");
+        up.Operations.Should().NotContain(o => o is DropColumnOperation || o is DropTableOperation || o is SqlOperation, "no destructive or backfill operations");
+    }
+
+    [Fact]
+    public async Task Controller_Detail_ProjectsContactsAndCompatibilityFields()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        var controller = new LocationController(
+            NewService(ctx),
+            Mock.Of<ILogger<LocationController>>())
+        {
+            ControllerContext = new ControllerContext { HttpContext = new DefaultHttpContext() }
+        };
+
+        var result = await controller.GetLocationById(seeded.Id, CancellationToken.None);
+
+        var ok = result.Should().BeOfType<OkObjectResult>().Subject;
+        using var json = JsonSerializer.SerializeToDocument(ok.Value);
+        var root = json.RootElement;
+
+        root.GetProperty("Phone").GetString().Should().Be("555-0100", "Phone mirrors the first site contact");
+        root.GetProperty("Contact").GetString().Should().Be("Alice Cooper", "Contact is the first contact display name");
+        var contacts = root.GetProperty("Contacts");
+        contacts.GetArrayLength().Should().Be(2);
+        contacts[0].GetProperty("Name").GetString().Should().Be("Alice Cooper");
+        contacts[0].GetProperty("Phone").GetString().Should().Be("555-0100");
+        contacts[1].GetProperty("Name").GetString().Should().Be("Bob Dillon");
+    }
+
+    [Fact]
+    public async Task Controller_List_ProjectsFirstContactAsLegacyContactField()
+    {
+        using var ctx = NewContext();
+        var seeded = await SeedLocationWithContactsAsync(ctx);
+        var controller = new LocationController(
+            NewService(ctx),
+            Mock.Of<ILogger<LocationController>>())
+        {
+            ControllerContext = new ControllerContext { HttpContext = new DefaultHttpContext() }
+        };
+
+        var result = await controller.GetLocationList(cancellationToken: CancellationToken.None);
+
+        var ok = result.Should().BeOfType<OkObjectResult>().Subject;
+        using var json = JsonSerializer.SerializeToDocument(ok.Value);
+        var row = json.RootElement.GetProperty("Data").EnumerateArray().Single();
+
+        row.GetProperty("Contact").GetString().Should().Be("Alice Cooper");
+        row.GetProperty("Phone").GetString().Should().Be("555-0100");
+        row.GetProperty("Contacts").GetArrayLength().Should().Be(2);
+    }
+}

Api.SeaHavenIndustries/Controllers/LocationController.cs

@@ -54,10 +54,11 @@ namespace Api.SeaHavenIndustries.Controllers
                     State = l.State,
                     ZipCode = l.Zip,
                     Phone = l.PhoneNumber,
-                    Contact = (string?)null,
+                    Contact = l.Contacts?.FirstOrDefault()?.Name,
                     ContactEmail = l.Email,
                     Status = l.Status,
-                    AccountId = l.AccountId
+                    AccountId = l.AccountId,
+                    Contacts = l.Contacts?.Select(c => new { c.Id, c.Name, c.Phone }).ToList()
                 });
 
                 var viewModel = new Pagination_DTO
@@ -98,10 +99,11 @@ namespace Api.SeaHavenIndustries.Controllers
                 location.State,
                 ZipCode = location.Zip,
                 Phone = location.PhoneNumber,
-                Contact = (string?)null,
+                Contact = location.Contacts?.FirstOrDefault()?.Name,
                 ContactEmail = location.Email,
                 location.Status,
-                location.AccountId
+                location.AccountId,
+                Contacts = location.Contacts?.Select(c => new { c.Id, c.Name, c.Phone }).ToList()
             };
 
             return Ok(result);
@@ -197,7 +199,8 @@ namespace Api.SeaHavenIndustries.Controllers
                 Phone = model.Phone,
                 ContactEmail = model.ContactEmail,
                 Status = model.Status,
-                AccountId = model.GetAccountId()
+                AccountId = model.GetAccountId(),
+                Contacts = MapSiteContacts(model.Contacts)
             };
         }
 
@@ -214,8 +217,19 @@ namespace Api.SeaHavenIndustries.Controllers
                 Phone = model.Phone,
                 ContactEmail = model.ContactEmail,
                 Status = model.Status,
-                AccountId = model.GetAccountId()
+                AccountId = model.GetAccountId(),
+                Contacts = MapSiteContacts(model.Contacts)
             };
         }
+
+        private static List<SiteContactRequestDTO>? MapSiteContacts(List<SiteContactInput_DTO>? contacts)
+        {
+            if (contacts == null)
+                return null;
+
+            return contacts
+                .Select(c => new SiteContactRequestDTO { Id = c.Id, Name = c.Name, Phone = c.Phone })
+                .ToList();
+        }
     }
 }

Api.SeaHavenIndustries/DTOs/EditLocation_DTO.cs

@@ -16,6 +16,7 @@ namespace Api.SeaHavenIndustries.DTOs
         public string? ContactEmail { get; set; }
         public string? Status { get; set; }
         public string? AccountId { get; set; }
+        public List<SiteContactInput_DTO>? Contacts { get; set; }
 
         public int? GetAccountId() => LocationAccountIdMapping.ParseOptional(AccountId);
 

Api.SeaHavenIndustries/DTOs/Location_DTO.cs

@@ -3,6 +3,14 @@ using SeaHaven.Services.DTOs;
 
 namespace Api.SeaHavenIndustries.DTOs
 {
+    // SH-138: additive site-contact write row (id optional on writes)
+    public class SiteContactInput_DTO
+    {
+        public int? Id { get; set; }
+        public string? Name { get; set; }
+        public string? Phone { get; set; }
+    }
+
     public class Location_DTO
     {
         public string? Title { get; set; }
@@ -16,6 +24,7 @@ namespace Api.SeaHavenIndustries.DTOs
         public string? ContactEmail { get; set; }
         public string? Status { get; set; }
         public string? AccountId { get; set; }
+        public List<SiteContactInput_DTO>? Contacts { get; set; }
 
         public int? GetAccountId() => LocationAccountIdMapping.ParseOptional(AccountId);
 

Data.SeaHavenIndustries/Migrations/20260915002525_SH138_SiteContacts.cs

@@ -0,0 +1,28 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Data.SeaHavenIndustries.Migrations
+{
+    /// <inheritdoc />
+    public partial class SH138_SiteContacts : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "SiteContactOrder",
+                table: "Contacts",
+                type: "int",
+                nullable: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "SiteContactOrder",
+                table: "Contacts");
+        }
+    }
+}

Data.SeaHavenIndustries/Migrations/ApplicationDbContextModelSnapshot.cs

@@ -651,6 +651,9 @@ namespace Data.SeaHavenIndustries.Migrations
                     b.Property<string>("PhoneNumber")
                         .HasColumnType("nvarchar(max)");
 
+                    b.Property<int?>("SiteContactOrder")
+                        .HasColumnType("int");
+
                     b.Property<string>("State")
                         .HasColumnType("nvarchar(max)");
 
@@ -2400,6 +2403,10 @@ namespace Data.SeaHavenIndustries.Migrations
                     b.Property<int?>("AccountId")
                         .HasColumnType("int");
 
+                    b.Property<string>("AdditionalContacts")
+                        .HasMaxLength(4000)
+                        .HasColumnType("nvarchar(4000)");
+
                     b.Property<string>("AfterPhotoAttachment")
                         .HasColumnType("nvarchar(max)");
 
@@ -2548,10 +2555,6 @@ namespace Data.SeaHavenIndustries.Migrations
                         .HasMaxLength(2000)
                         .HasColumnType("nvarchar(2000)");
 
-                    b.Property<string>("AdditionalContacts")
-                        .HasMaxLength(4000)
-                        .HasColumnType("nvarchar(4000)");
-
                     b.Property<string>("PocPhone")
                         .HasMaxLength(50)
                         .HasColumnType("nvarchar(50)");
@@ -3224,16 +3227,6 @@ namespace Data.SeaHavenIndustries.Migrations
                     b.Navigation("Account");
                 });
 
-            modelBuilder.Entity("Data.SeaHavenIndustries.Locations", b =>
-                {
-                    b.HasOne("Data.SeaHavenIndustries.Accounts", "Account")
-                        .WithMany()
-                        .HasForeignKey("AccountId")
-                        .OnDelete(DeleteBehavior.Restrict);
-
-                    b.Navigation("Account");
-                });
-
             modelBuilder.Entity("Data.SeaHavenIndustries.Assets", b =>
                 {
                     b.HasOne("Data.SeaHavenIndustries.Accounts", "Account")
@@ -3294,7 +3287,7 @@ namespace Data.SeaHavenIndustries.Migrations
                         .OnDelete(DeleteBehavior.Restrict);
 
                     b.HasOne("Data.SeaHavenIndustries.Locations", "Location")
-                        .WithMany()
+                        .WithMany("Contacts")
                         .HasForeignKey("LocationId")
                         .OnDelete(DeleteBehavior.Restrict);
 
@@ -3474,6 +3467,16 @@ namespace Data.SeaHavenIndustries.Migrations
                     b.Navigation("WorkOrder");
                 });
 
+            modelBuilder.Entity("Data.SeaHavenIndustries.Locations", b =>
+                {
+                    b.HasOne("Data.SeaHavenIndustries.Accounts", "Account")
+                        .WithMany()
+                        .HasForeignKey("AccountId")
+                        .OnDelete(DeleteBehavior.Restrict);
+
+                    b.Navigation("Account");
+                });
+
             modelBuilder.Entity("Data.SeaHavenIndustries.PMSchedules", b =>
                 {
                     b.HasOne("Data.SeaHavenIndustries.Assets", "Asset")
@@ -3869,7 +3872,7 @@ namespace Data.SeaHavenIndustries.Migrations
 
             modelBuilder.Entity("Data.SeaHavenIndustries.Locations", b =>
                 {
-                    b.Navigation("Account");
+                    b.Navigation("Contacts");
 
                     b.Navigation("Templates");
 

Data.SeaHavenIndustries/Models/Contacts.cs

@@ -30,6 +30,9 @@ namespace Data.SeaHavenIndustries
         public int? LocationId { get; set; }
         public int? AccountId { get; set; }
 
+        // SH-138: dense zero-based display order for site-managed contacts
+        public int? SiteContactOrder { get; set; }
+
         // Navigation Properties
         [ForeignKey(nameof(LocationId))]
         public Locations? Location { get; set; }

Data.SeaHavenIndustries/Models/Locations.cs

@@ -30,5 +30,8 @@ namespace Data.SeaHavenIndustries
         // Navigation Properties
         public ICollection<Template>? Templates { get; set; }
         public ICollection<WorkOrder>? workOrders { get; set; }
+
+        // SH-138: site contacts (soft-deleted rows stay for historical WorkOrderContacts)
+        public ICollection<Contacts>? Contacts { get; set; }
     }
 }

SeaHaven.DataServices/Implementation/LocationDataService.cs

@@ -166,12 +166,30 @@ namespace SeaHaven.DataServices.Implementation
         {
             return await _context.Locations
                 .AsNoTracking()
+                .Include(l => l.Contacts.Where(c => c.IsDeleted != true))
                 .FirstOrDefaultAsync(l => l.Id == id, cancellationToken);
         }
 
         public async Task<Locations?> GetByIdForUpdateAsync(int id, CancellationToken cancellationToken)
         {
-            return await _context.Locations.FindAsync(new object[] { id }, cancellationToken);
+            return await _context.Locations
+                .Include(l => l.Contacts)
+                .FirstOrDefaultAsync(l => l.Id == id, cancellationToken);
+        }
+
+        public async Task<IReadOnlyList<Contacts>> GetSiteContactsByLocationIdsAsync(
+            IReadOnlyCollection<int> locationIds,
+            CancellationToken cancellationToken)
+        {
+            if (locationIds.Count == 0)
+                return Array.Empty<Contacts>();
+
+            return await _context.Contacts
+                .AsNoTracking()
+                .Where(c => c.LocationId != null && locationIds.Contains(c.LocationId.Value) && c.IsDeleted != true)
+                .OrderBy(c => c.SiteContactOrder)
+                .ThenBy(c => c.Id)
+                .ToListAsync(cancellationToken);
         }
 
         public async Task<Locations> AddAsync(Locations location, CancellationToken cancellationToken)

SeaHaven.DataServices/Interfaces/ILocationDataService.cs

@@ -37,6 +37,15 @@ namespace SeaHaven.DataServices.Interfaces
         Task<(List<Locations> Items, int TotalCount)> GetListPagedAsync(int page, int pageSize, string? search, IReadOnlyCollection<string>? states, CancellationToken cancellationToken);
         Task<Locations?> GetDetailByIdAsync(int id, CancellationToken cancellationToken);
         Task<Locations?> GetByIdForUpdateAsync(int id, CancellationToken cancellationToken);
+
+        /// <summary>
+        /// SH-138: single bounded read of active site contacts for a page of locations,
+        /// ordered by SiteContactOrder then Id. Deleted contacts are excluded.
+        /// </summary>
+        Task<IReadOnlyList<Contacts>> GetSiteContactsByLocationIdsAsync(
+            IReadOnlyCollection<int> locationIds,
+            CancellationToken cancellationToken);
+
         Task<Locations> AddAsync(Locations location, CancellationToken cancellationToken);
         Task UpdateAsync(Locations location, CancellationToken cancellationToken);
         Task<bool> DeleteByIdAsync(int id, CancellationToken cancellationToken);

SeaHaven.Services/DTOs/LocationDTOs.cs

@@ -16,6 +16,25 @@ namespace SeaHaven.Services.DTOs
         public int? AccountId { get; set; }
         public DateTime? CreatedDate { get; set; }
         public string? CreatedBy { get; set; }
+
+        /// <summary>SH-138: ordered site contacts; null when the site has none.</summary>
+        public IReadOnlyList<SiteContactResponseDTO>? Contacts { get; set; }
+    }
+
+    /// <summary>SH-138: additive site-contact write row. Id is optional on writes.</summary>
+    public class SiteContactRequestDTO
+    {
+        public int? Id { get; set; }
+        public string? Name { get; set; }
+        public string? Phone { get; set; }
+    }
+
+    /// <summary>SH-138: site-contact read row, ordered by SiteContactOrder then Id.</summary>
+    public class SiteContactResponseDTO
+    {
+        public int Id { get; set; }
+        public string? Name { get; set; }
+        public string? Phone { get; set; }
     }
 
     public class CreateLocationDTO
@@ -50,6 +69,9 @@ namespace SeaHaven.Services.DTOs
         public string? ContactEmail { get; set; }
         public string? Status { get; set; }
         public int? AccountId { get; set; }
+
+        /// <summary>SH-138: null keeps legacy behavior; empty array is a validation error.</summary>
+        public List<SiteContactRequestDTO>? Contacts { get; set; }
     }
 
     public class LocationUpdateRequestDTO
@@ -64,6 +86,9 @@ namespace SeaHaven.Services.DTOs
         public string? ContactEmail { get; set; }
         public string? Status { get; set; }
         public int? AccountId { get; set; }
+
+        /// <summary>SH-138: null keeps legacy behavior and must not mutate contact rows.</summary>
+        public List<SiteContactRequestDTO>? Contacts { get; set; }
     }
 
     public class SiteOptionDTO

SeaHaven.Services/Implementation/LocationService.cs

@@ -49,13 +49,13 @@ namespace SeaHaven.Services.Implementation
         public async Task<IEnumerable<LocationDTO>> GetAllLocationsAsync()
         {
             var locations = await _locationDataService.GetAllAsync();
-            return locations.Select(MapToDTO);
+            return locations.Select(l => MapToDTO(l));
         }
 
         public async Task<IEnumerable<LocationDTO>> GetLocationsByAccountIdAsync(int accountId)
         {
             var locations = await _locationDataService.GetByAccountIdAsync(accountId);
-            return locations.Select(MapToDTO);
+            return locations.Select(l => MapToDTO(l));
         }
 
         public async Task<PagedResult<LocationDTO>> GetLocationsPagedAsync(int page, int pageSize, string? search = null)
@@ -63,7 +63,7 @@ namespace SeaHaven.Services.Implementation
             var (items, totalCount) = await _locationDataService.GetPagedAsync(page, pageSize, search);
             return new PagedResult<LocationDTO>
             {
-                Items = items.Select(MapToDTO).ToList(),
+                Items = items.Select(l => MapToDTO(l)).ToList(),
                 TotalCount = totalCount,
                 Page = page,
                 PageSize = pageSize
@@ -171,9 +171,13 @@ namespace SeaHaven.Services.Implementation
             var stateFilter = NormalizeStateFilter(states);
             var storageStateFilter = stateFilter == null ? null : UsStateCodes.ExpandStorageValues(stateFilter);
             var (items, totalCount) = await _locationDataService.GetListPagedAsync(page, pageSize, search, storageStateFilter, cancellationToken);
+
+            // SH-138: one bounded contact read for the whole page, never per row.
+            var contactsByLocation = await GetSiteContactsByLocationIdsAsync(items, cancellationToken);
+
             return new PagedResult<LocationDTO>
             {
-                Items = items.Select(MapToDTO).ToList(),
+                Items = items.Select(l => MapToDTO(l, contactsByLocation)).ToList(),
                 TotalCount = totalCount,
                 Page = page,
                 PageSize = pageSize
@@ -233,6 +237,11 @@ namespace SeaHaven.Services.Implementation
                 AccountId = request.AccountId
             };
 
+            if (request.Contacts is List<SiteContactRequestDTO> contacts)
+            {
+                ApplySiteContactsForCreate(location, contacts, GetActorId(user));
+            }
+
             await _locationDataService.AddAsync(location, cancellationToken);
         }
 
@@ -264,6 +273,12 @@ namespace SeaHaven.Services.Implementation
                 location.AccountId = accountId;
             }
 
+            // SH-138: null contacts keeps legacy behavior and must not mutate contact rows.
+            if (request.Contacts is List<SiteContactRequestDTO> contacts)
+            {
+                ApplySiteContactsForUpdate(location, contacts, GetActorId(user));
+            }
+
             await _locationDataService.UpdateAsync(location, cancellationToken);
         }
 
@@ -326,7 +341,153 @@ namespace SeaHaven.Services.Implementation
         }
 
         // Private helper methods
-        private LocationDTO MapToDTO(Locations location)
+
+        private static string? GetActorId(ClaimsPrincipal user) =>
+            user.FindFirst(ClaimTypes.NameIdentifier)?.Value;
+
+        private static void ThrowOnInvalidContacts(List<SiteContactRequestDTO> contacts)
+        {
+            var failures = SiteContactsValidation.Validate(contacts);
+            if (failures.Count > 0)
+                throw new ValidationException(failures);
+        }
+
+        private static void ApplySiteContactsForCreate(
+            Locations location,
+            List<SiteContactRequestDTO> contacts,
+            string? actorId)
+        {
+            ThrowOnInvalidContacts(contacts);
+
+            var now = DateTime.Now;
+            var siteContacts = contacts
+                .Select((row, index) => new Contacts
+                {
+                    FirstName = row.Name!.Trim(),
+                    MiddleName = null,
+                    LastName = null,
+                    PhoneNumber = row.Phone!.Trim(),
+                    SiteContactOrder = index,
+                    AccountId = location.AccountId,
+                    CreatedDate = now,
+                    createdby = actorId
+                })
+                .ToList();
+            location.Contacts = siteContacts;
+
+            // The first site contact mirrors Location.PhoneNumber for legacy consumers.
+            location.PhoneNumber = siteContacts[0].PhoneNumber;
+        }
+
+        private static void ApplySiteContactsForUpdate(
+            Locations location,
+            List<SiteContactRequestDTO> contacts,
+            string? actorId)
+        {
+            ThrowOnInvalidContacts(contacts);
+
+            var existingById = (location.Contacts ?? Enumerable.Empty<Contacts>())
+                .ToDictionary(c => c.Id);
+
+            var keptIds = new HashSet<int>();
+            for (var i = 0; i < contacts.Count; i++)
+            {
+                var row = contacts[i];
+                var name = row.Name!.Trim();
+                var phone = row.Phone!.Trim();
+
+                if (row.Id is int id)
+                {
+                    if (!existingById.TryGetValue(id, out var existing)
+                        || existing.LocationId != location.Id
+                        || existing.IsDeleted == true)
+                    {
+                        throw new ValidationException(new[]
+                        {
+                            new ValidationFailure(
+                                $"{nameof(LocationUpdateRequestDTO.Contacts)}[{i}].{nameof(SiteContactRequestDTO.Id)}",
+                                $"Contact {id} does not exist, is deleted, or does not belong to this location.")
+                        });
+                    }
+
+                    keptIds.Add(id);
+                    existing.FirstName = name;
+                    existing.MiddleName = null;
+                    existing.LastName = null;
+                    existing.PhoneNumber = phone;
+                    existing.SiteContactOrder = i;
+                    existing.AccountId = location.AccountId;
+                    existing.LastModificationTime = DateTime.Now;
+                }
+                else
+                {
+                    location.Contacts ??= new List<Contacts>();
+                    location.Contacts.Add(new Contacts
+                    {
+                        FirstName = name,
+                        MiddleName = null,
+                        LastName = null,
+                        PhoneNumber = phone,
+                        SiteContactOrder = i,
+                        AccountId = location.AccountId,
+                        CreatedDate = DateTime.Now,
+                        createdby = actorId
+                    });
+                }
+            }
+
+            // Rows omitted from the request are soft deleted so historical
+            // WorkOrderContacts keep rendering.
+            var now = DateTime.Now;
+            foreach (var existing in existingById.Values)
+            {
+                if (keptIds.Contains(existing.Id) || existing.IsDeleted == true)
+                    continue;
+
+                existing.IsDeleted = true;
+                existing.DeleterUserId = actorId;
+                existing.DeletionTime = now;
+                existing.LastModificationTime = now;
+            }
+
+            // The first site contact mirrors Location.PhoneNumber for legacy consumers.
+            location.PhoneNumber = contacts[0].Phone!.Trim();
+        }
+
+        private async Task<IReadOnlyDictionary<int, IReadOnlyList<Contacts>>> GetSiteContactsByLocationIdsAsync(
+            List<Locations> items,
+            CancellationToken cancellationToken)
+        {
+            if (items.Count == 0)
+                return new Dictionary<int, IReadOnlyList<Contacts>>();
+
+            var rows = await _locationDataService.GetSiteContactsByLocationIdsAsync(
+                items.Select(l => l.Id).ToList(),
+                cancellationToken);
+
+            return rows
+                .GroupBy(c => c.LocationId!.Value)
+                .ToDictionary(g => g.Key, g => (IReadOnlyList<Contacts>)g.ToList());
+        }
+
+        private static IReadOnlyList<SiteContactResponseDTO> MapSiteContacts(IEnumerable<Contacts>? contacts)
+        {
+            if (contacts == null)
+                return new List<SiteContactResponseDTO>();
+
+            return contacts
+                .OrderBy(c => c.SiteContactOrder)
+                .ThenBy(c => c.Id)
+                .Select(c => new SiteContactResponseDTO
+                {
+                    Id = c.Id,
+                    Name = c.FirstName,
+                    Phone = c.PhoneNumber
+                })
+                .ToList();
+        }
+
+        private LocationDTO MapToDTO(Locations location, IReadOnlyDictionary<int, IReadOnlyList<Contacts>>? contactsByLocation = null)
         {
             return new LocationDTO
             {
@@ -343,7 +504,10 @@ namespace SeaHaven.Services.Implementation
                 Status = location.Status,
                 AccountId = location.AccountId,
                 CreatedDate = location.CreatedDate,
-                CreatedBy = location.createdby
+                CreatedBy = location.createdby,
+                Contacts = contactsByLocation != null && contactsByLocation.TryGetValue(location.Id, out var contacts)
+                    ? MapSiteContacts(contacts)
+                    : MapSiteContacts(location.Contacts?.Where(c => c.IsDeleted != true))
             };
         }
     }

SeaHaven.Services/Validation/SiteContactValidation.cs

@@ -0,0 +1,81 @@
+using FluentValidation.Results;
+using SeaHaven.Services.DTOs;
+
+namespace SeaHaven.Services.Validation
+{
+    /// <summary>
+    /// SH-138 site-contact request validation shared by location create and update.
+    /// Null contacts means legacy behavior (no validation, no mutation);
+    /// a present array must contain 1..20 complete rows.
+    /// </summary>
+    public static class SiteContactsValidation
+    {
+        public const int MaxContacts = 20;
+        public const int MaxNameLength = 100;
+        public const int MaxPhoneLength = 20;
+
+        public static List<ValidationFailure> Validate(IReadOnlyList<SiteContactRequestDTO> contacts)
+        {
+            var failures = new List<ValidationFailure>();
+
+            if (contacts.Count == 0)
+            {
+                failures.Add(new ValidationFailure(
+                    nameof(LocationCreateRequestDTO.Contacts),
+                    "Contacts must contain at least one contact when provided."));
+                return failures;
+            }
+
+            if (contacts.Count > MaxContacts)
+            {
+                failures.Add(new ValidationFailure(
+                    nameof(LocationCreateRequestDTO.Contacts),
+                    $"Contacts cannot exceed {MaxContacts} entries."));
+                return failures;
+            }
+
+            var seenIds = new HashSet<int>();
+            for (var i = 0; i < contacts.Count; i++)
+            {
+                var row = contacts[i];
+                var name = row.Name?.Trim();
+                var phone = row.Phone?.Trim();
+
+                if (string.IsNullOrWhiteSpace(name))
+                {
+                    failures.Add(new ValidationFailure(
+                        $"{nameof(LocationCreateRequestDTO.Contacts)}[{i}].{nameof(SiteContactRequestDTO.Name)}",
+                        "Contact name is required."));
+                }
+                else if (name.Length > MaxNameLength)
+                {
+                    failures.Add(new ValidationFailure(
+                        $"{nameof(LocationCreateRequestDTO.Contacts)}[{i}].{nameof(SiteContactRequestDTO.Name)}",
+                        $"Contact name cannot exceed {MaxNameLength} characters."));
+                }
+
+                if (string.IsNullOrWhiteSpace(phone))
+                {
+                    failures.Add(new ValidationFailure(
+                        $"{nameof(LocationCreateRequestDTO.Contacts)}[{i}].{nameof(SiteContactRequestDTO.Phone)}",
+                        "Contact phone is required."));
+                }
+                else if (phone.Length > MaxPhoneLength)
+                {
+                    failures.Add(new ValidationFailure(
+                        $"{nameof(LocationCreateRequestDTO.Contacts)}[{i}].{nameof(SiteContactRequestDTO.Phone)}",
+                        $"Contact phone cannot exceed {MaxPhoneLength} characters."));
+                }
+
+                if (row.Id is int id && !seenIds.Add(id))
+                {
+                    failures.Add(new ValidationFailure(
+                        $"{nameof(LocationCreateRequestDTO.Contacts)}[{i}].{nameof(SiteContactRequestDTO.Id)}",
+                        $"Contact id {id} appears more than once."));
+                }
+            }
+
+            return failures;
+        }
+    }
+}

SeaHavenIndustries.Tests/WorkOrderAccountScopeTests.cs

@@ -841,6 +841,10 @@ public class WorkOrderAccountScopeTests
             => _inner.GetDetailByIdAsync(id, cancellationToken);
         public Task<Locations?> GetByIdForUpdateAsync(int id, CancellationToken cancellationToken)
             => _inner.GetByIdForUpdateAsync(id, cancellationToken);
+        public Task<IReadOnlyList<Contacts>> GetSiteContactsByLocationIdsAsync(
+            IReadOnlyCollection<int> locationIds,
+            CancellationToken cancellationToken)
+            => _inner.GetSiteContactsByLocationIdsAsync(locationIds, cancellationToken);
         public Task<Locations> AddAsync(Locations location, CancellationToken cancellationToken)
             => _inner.AddAsync(location, cancellationToken);
         public Task UpdateAsync(Locations location, CancellationToken cancellationToken)