feat(email): add durable send ledger

Tracks only idempotency and delivery metadata; recipient, subject, and body are excluded. No provider send path is enabled.

JobTrackerApi.Tests/EmailSendAttemptStoreTests.cs

@@ -0,0 +1,104 @@
+using JobTrackerApi.Data;
+using JobTrackerApi.Models;
+using JobTrackerApi.Services;
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Moq;
+using Xunit;
+
+namespace JobTrackerApi.Tests;
+
+public sealed class EmailSendAttemptStoreTests
+{
+    [Fact]
+    public async Task Creation_is_idempotent_and_rejects_payload_reuse()
+    {
+        await using var fixture = await Fixture.CreateAsync();
+        var store = fixture.Store("user-1");
+        var requestId = Guid.NewGuid().ToString();
+        var first = await store.CreateAsync(new(fixture.JobId, "gmail", requestId, Hash('a')), default);
+        var duplicate = await store.CreateAsync(new(fixture.JobId, "gmail", requestId, Hash('a')), default);
+
+        Assert.True(first.Created);
+        Assert.False(duplicate.Created);
+        Assert.Equal(first.Attempt.Id, duplicate.Attempt.Id);
+        await Assert.ThrowsAsync<EmailSendConflictException>(() =>
+            store.CreateAsync(new(fixture.JobId, "gmail", requestId, Hash('b')), default));
+    }
+
+    [Fact]
+    public async Task State_machine_never_restarts_terminal_or_uncertain_attempts()
+    {
+        await using var fixture = await Fixture.CreateAsync();
+        var store = fixture.Store("user-1");
+        var created = await store.CreateAsync(new(fixture.JobId, "microsoft", Guid.NewGuid().ToString(), Hash('c')), default);
+
+        Assert.Equal(1, await store.BeginAsync(created.Attempt.Id, default));
+        Assert.Equal(0, await store.BeginAsync(created.Attempt.Id, default));
+        Assert.Equal(1, await store.MarkUncertainAsync(created.Attempt.Id, "transport_interrupted", default));
+        Assert.Equal(0, await store.MarkSentAsync(created.Attempt.Id, "late-message", default));
+
+        var stored = await store.GetAsync(created.Attempt.Id, default);
+        Assert.Equal(EmailSendStatuses.Uncertain, stored!.Status);
+        Assert.Equal("transport_interrupted", stored.FailureCategory);
+        Assert.NotNull(stored.CompletedAtUtc);
+    }
+
+    [Fact]
+    public async Task Direct_attempt_ids_are_tenant_scoped_and_store_no_message_content()
+    {
+        await using var fixture = await Fixture.CreateAsync();
+        var ownerStore = fixture.Store("user-1");
+        var created = await ownerStore.CreateAsync(new(fixture.JobId, "gmail", Guid.NewGuid().ToString(), Hash('d')), default);
+
+        Assert.Null(await fixture.Store("user-2").GetAsync(created.Attempt.Id, default));
+        Assert.DoesNotContain(typeof(EmailSendAttempt).GetProperties(), property =>
+            property.Name.Contains("Subject", StringComparison.OrdinalIgnoreCase) ||
+            property.Name.Contains("Body", StringComparison.OrdinalIgnoreCase) ||
+            property.Name.Contains("Recipient", StringComparison.OrdinalIgnoreCase));
+    }
+
+    private static string Hash(char value) => new(value, 64);
+
+    private sealed class Fixture(SqliteConnection connection, DbContextOptions<JobTrackerContext> options, int jobId) : IAsyncDisposable
+    {
+        private readonly List<JobTrackerContext> contexts = new();
+        public int JobId { get; } = jobId;
+
+        public static async Task<Fixture> CreateAsync()
+        {
+            var connection = new SqliteConnection("Data Source=:memory:");
+            await connection.OpenAsync();
+            var options = new DbContextOptionsBuilder<JobTrackerContext>().UseSqlite(connection).Options;
+            await using var db = CreateDb(options, "user-1");
+            await db.Database.EnsureCreatedAsync();
+            var company = new Company { Name = "Acme", OwnerUserId = "user-1" };
+            db.Companies.Add(company);
+            await db.SaveChangesAsync();
+            var job = new JobApplication { JobTitle = "Backend", CompanyId = company.Id, OwnerUserId = "user-1" };
+            db.JobApplications.Add(job);
+            await db.SaveChangesAsync();
+            return new Fixture(connection, options, job.Id);
+        }
+
+        public EmailSendAttemptStore Store(string userId)
+        {
+            var db = CreateDb(options, userId);
+            contexts.Add(db);
+            return new EmailSendAttemptStore(db, TimeProvider.System);
+        }
+
+        private static JobTrackerContext CreateDb(DbContextOptions<JobTrackerContext> options, string userId)
+        {
+            var currentUser = new Mock<ICurrentUserService>();
+            currentUser.SetupGet(service => service.UserId).Returns(userId);
+            return new JobTrackerContext(options, currentUser.Object);
+        }
+
+        public async ValueTask DisposeAsync()
+        {
+            foreach (var context in contexts) await context.DisposeAsync();
+            await connection.DisposeAsync();
+        }
+    }
+}