fix(email): preserve draft send identity

Persist and export each draft's idempotency UUID so refresh and edits cannot create a fresh delivery identity. Add reversible provider-specific migration SQL.

JobTrackerApi.Tests/BackgroundWorkerTenantTests.cs

@@ -154,6 +154,7 @@ public sealed class BackgroundWorkerTenantTests
                 var draft = Assert.Single(rootElement.GetProperty("EmailDrafts").EnumerateArray());
                 Assert.Equal(owner == "user-1" ? "one@example.test" : "two@example.test", draft.GetProperty("To").GetString());
                 Assert.Equal(owner == "user-1" ? "Private draft one" : "Private draft two", draft.GetProperty("BodyText").GetString());
+                Assert.True(Guid.TryParse(draft.GetProperty("ClientRequestId").GetString(), out _));
                 Assert.Equal(1, draft.GetProperty("Revision").GetInt64());
             }
             owners.Sort(StringComparer.Ordinal);
@@ -176,6 +177,7 @@ public sealed class BackgroundWorkerTenantTests
         Subject = "Synthetic export subject",
         BodyText = body,
         ThreadId = "synthetic-thread",
+        ClientRequestId = Guid.NewGuid().ToString("D"),
         CreatedAtUtc = DateTime.UtcNow.AddMinutes(-5),
         UpdatedAtUtc = DateTime.UtcNow,
     };

JobTrackerApi.Tests/BackupControllerTests.cs

@@ -62,6 +62,7 @@ public sealed class BackupControllerTests
             Subject = "Synthetic export subject",
             BodyText = "Synthetic readable draft body.",
             ThreadId = "synthetic-thread",
+            ClientRequestId = "00000000-0000-4000-8000-000000000123",
             Revision = 3,
             CreatedAtUtc = DateTime.UtcNow.AddMinutes(-5),
             UpdatedAtUtc = DateTime.UtcNow,
@@ -75,6 +76,7 @@ public sealed class BackupControllerTests
             To = "other@example.test",
             Subject = "Other tenant subject",
             BodyText = "Other tenant private body.",
+            ClientRequestId = "00000000-0000-4000-8000-000000000456",
             CreatedAtUtc = DateTime.UtcNow,
             UpdatedAtUtc = DateTime.UtcNow,
         });
@@ -102,6 +104,7 @@ public sealed class BackupControllerTests
         Assert.Equal("Synthetic export subject", draft.GetProperty("Subject").GetString());
         Assert.Equal("Synthetic readable draft body.", draft.GetProperty("BodyText").GetString());
         Assert.Equal("synthetic-thread", draft.GetProperty("ThreadId").GetString());
+        Assert.Equal("00000000-0000-4000-8000-000000000123", draft.GetProperty("ClientRequestId").GetString());
         Assert.Equal(3, draft.GetProperty("Revision").GetInt64());
     }
 

JobTrackerApi.Tests/EmailDraftPersistenceTests.cs

@@ -64,6 +64,7 @@ public sealed class EmailDraftPersistenceTests
         Subject = "Synthetic draft",
         BodyText = "Synthetic private draft body.",
         ThreadId = "thread-1",
+        ClientRequestId = Guid.NewGuid().ToString("D"),
         CreatedAtUtc = DateTime.UtcNow,
         UpdatedAtUtc = DateTime.UtcNow,
     };

JobTrackerApi.Tests/EmailDraftsControllerTests.cs

@@ -40,6 +40,7 @@ public sealed class EmailDraftsControllerTests
         Assert.Equal("gmail", created.Provider);
         Assert.Equal(1, created.Revision);
         Assert.Empty(created.To);
+        Assert.True(Guid.TryParse(created.ClientRequestId, out _));
 
         Assert.IsType<BadRequestObjectResult>((await controller.Create(
             new EmailDraftsController.CreateDraftRequest(fixture.UserOneJobId, "unknown", "", "", "", null), default)).Result);
@@ -63,6 +64,9 @@ public sealed class EmailDraftsControllerTests
         var ownList = Assert.IsAssignableFrom<IReadOnlyList<EmailDraftsController.DraftDto>>(
             Assert.IsType<OkObjectResult>((await controller.List(fixture.UserOneJobId, default)).Result).Value);
         Assert.Equal(fixture.UserOneDraftId, Assert.Single(ownList).Id);
+        var allOwnDrafts = Assert.IsAssignableFrom<IReadOnlyList<EmailDraftsController.DraftDto>>(
+            Assert.IsType<OkObjectResult>((await controller.List(null, default)).Result).Value);
+        Assert.Equal(fixture.UserOneDraftId, Assert.Single(allOwnDrafts).Id);
     }
 
     [Fact]
@@ -72,11 +76,13 @@ public sealed class EmailDraftsControllerTests
         await using (var userOneDb = fixture.Context("user-1"))
         {
             var userOne = Controller(userOneDb, "user-1");
+            var originalRequestId = (await userOneDb.EmailDrafts.AsNoTracking().SingleAsync()).ClientRequestId;
             var updatedResult = await userOne.Update(fixture.UserOneDraftId,
                 new EmailDraftsController.UpdateDraftRequest(1, "new@example.test", "Updated", "Updated body"), default);
             var updated = Assert.IsType<EmailDraftsController.DraftDto>(Assert.IsType<OkObjectResult>(updatedResult.Result).Value);
             Assert.Equal(2, updated.Revision);
             Assert.Equal("Updated body", updated.BodyText);
+            Assert.Equal(originalRequestId, updated.ClientRequestId);
 
             Assert.IsType<ConflictObjectResult>((await userOne.Update(fixture.UserOneDraftId,
                 new EmailDraftsController.UpdateDraftRequest(1, "stale@example.test", "Stale", "Stale body"), default)).Result);
@@ -190,6 +196,7 @@ public sealed class EmailDraftsControllerTests
             To = recipient,
             Subject = "Synthetic",
             BodyText = "Synthetic private draft.",
+            ClientRequestId = Guid.NewGuid().ToString("D"),
             CreatedAtUtc = DateTime.UtcNow,
             UpdatedAtUtc = DateTime.UtcNow,
         };