diff --git a/Directory.Packages.props b/Directory.Packages.props
index aff6ed2..39c7d4a 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -14,6 +14,10 @@
     <PackageVersion Include="AngleSharp" Version="1.5.2" />
   </ItemGroup>
 
+  <ItemGroup Label="Core">
+    <PackageVersion Include="AndreGoepel.Core" Version="1.0.1" />
+  </ItemGroup>
+
   <ItemGroup Label="Marten">
     <PackageVersion Include="Marten" Version="9.19.0" />
     <PackageVersion Include="Marten.AspNetCore" Version="9.19.0" />
diff --git a/src/AndreGoepel.Marten.Identity.Blazor/Email/UserInvitationMailer.cs b/src/AndreGoepel.Marten.Identity.Blazor/Email/UserInvitationMailer.cs
index 0949fe6..c168d48 100644
--- a/src/AndreGoepel.Marten.Identity.Blazor/Email/UserInvitationMailer.cs
+++ b/src/AndreGoepel.Marten.Identity.Blazor/Email/UserInvitationMailer.cs
@@ -1,4 +1,5 @@
 using System.Text;
+using AndreGoepel.Core;
 using AndreGoepel.Marten.Identity.Users;
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.Identity;
@@ -29,10 +30,10 @@ public async Task<IdentityResult> InviteAsync(
     )
     {
         var result = await invitations.InviteAsync(email, roles, cancellationToken);
-        if (!result.Succeeded)
-            return result.Result;
+        if (!result.IsSuccess)
+            return Failed(result.Error);
 
-        await SendAsync(result, email, cancellationToken);
+        await SendAsync(result.Value!, email, cancellationToken);
         return IdentityResult.Success;
     }
 
@@ -42,31 +43,42 @@ public async Task<IdentityResult> ResendAsync(
     )
     {
         var result = await invitations.ResendAsync(user, cancellationToken);
-        if (!result.Succeeded)
-            return result.Result;
+        if (!result.IsSuccess)
+            return Failed(result.Error);
 
-        await SendAsync(result, user.Email!, cancellationToken);
+        await SendAsync(result.Value!, user.Email!, cancellationToken);
         return IdentityResult.Success;
     }
 
+    /// <summary>
+    /// Adapts a <see cref="Result{T}"/> failure back into the <see cref="IdentityResult"/>
+    /// this class's own callers (the admin dialog and Users page) expect. A generic error
+    /// code is used because neither caller branches on it today, only on the joined
+    /// description text.
+    /// </summary>
+    private static IdentityResult Failed(string description) =>
+        IdentityResult.Failed(
+            new IdentityError { Code = "InvitationFailed", Description = description }
+        );
+
     private async Task SendAsync(
-        UserInvitationResult result,
+        UserInvitationDetails details,
         string email,
         CancellationToken cancellationToken
     )
     {
         // userId identifies the account; the token rides in the query Base64Url-encoded so
         // it survives the URL intact.
-        var encodedCode = WebEncoders.Base64UrlEncode(Encoding.UTF8.GetBytes(result.Token!));
+        var encodedCode = WebEncoders.Base64UrlEncode(Encoding.UTF8.GetBytes(details.Token));
         var link = navigation.GetUriWithQueryParameters(
             navigation.ToAbsoluteUri("Account/AcceptInvitation").AbsoluteUri,
-            new Dictionary<string, object?> { ["userId"] = result.User!.Id, ["code"] = encodedCode }
+            new Dictionary<string, object?> { ["userId"] = details.User.Id, ["code"] = encodedCode }
         );
 
         // Pass the raw URL. HTML-encoding is the sender's job, done only if it embeds the
         // link in HTML — encoding here turns the query separator into "&amp;", which breaks
         // the link for any sender that emits plain text (e.g. a dev logger writing it to a
         // console, where "&amp;" is copied verbatim into the browser and splits the query).
-        await emailSender.SendInvitationLinkAsync(result.User, email, link, cancellationToken);
+        await emailSender.SendInvitationLinkAsync(details.User, email, link, cancellationToken);
     }
 }
diff --git a/src/AndreGoepel.Marten.Identity.Blazor/packages.lock.json b/src/AndreGoepel.Marten.Identity.Blazor/packages.lock.json
index 71e4576..45c10a7 100644
--- a/src/AndreGoepel.Marten.Identity.Blazor/packages.lock.json
+++ b/src/AndreGoepel.Marten.Identity.Blazor/packages.lock.json
@@ -184,6 +184,7 @@
       "andregoepel.marten.identity": {
         "type": "Project",
         "dependencies": {
+          "AndreGoepel.Core": "[1.0.1, )",
           "AndreGoepel.Marten.Configuration": "[1.0.1, )",
           "AndreGoepel.Marten.Identity.Abstractions": "[1.8.0, )",
           "Marten": "[9.19.0, )",
@@ -194,6 +195,12 @@
       "andregoepel.marten.identity.abstractions": {
         "type": "Project"
       },
+      "AndreGoepel.Core": {
+        "type": "CentralTransitive",
+        "requested": "[1.0.1, )",
+        "resolved": "1.0.1",
+        "contentHash": "jA27iMianyxUdrCtz5b6KxZOYxXlhZqkxDVKD6sed1sDCHF1upfV28CnczJ6kYPcrqJNj9+cDaxMWPlNvDkjcA=="
+      },
       "Marten.AspNetCore": {
         "type": "CentralTransitive",
         "requested": "[9.19.0, )",
diff --git a/src/AndreGoepel.Marten.Identity/AndreGoepel.Marten.Identity.csproj b/src/AndreGoepel.Marten.Identity/AndreGoepel.Marten.Identity.csproj
index 6e655ec..2f37eb7 100644
--- a/src/AndreGoepel.Marten.Identity/AndreGoepel.Marten.Identity.csproj
+++ b/src/AndreGoepel.Marten.Identity/AndreGoepel.Marten.Identity.csproj
@@ -27,6 +27,7 @@
     <PackageReference Include="Marten.AspNetCore" />
     <PackageReference Include="Quartz.Extensions.Hosting" />
     <PackageReference Include="AndreGoepel.Marten.Configuration" />
+    <PackageReference Include="AndreGoepel.Core" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/AndreGoepel.Marten.Identity/Users/UserInvitationService.cs b/src/AndreGoepel.Marten.Identity/Users/UserInvitationService.cs
index e2aa8bc..6b796ed 100644
--- a/src/AndreGoepel.Marten.Identity/Users/UserInvitationService.cs
+++ b/src/AndreGoepel.Marten.Identity/Users/UserInvitationService.cs
@@ -1,4 +1,5 @@
-using AndreGoepel.Marten.Identity.Services;
+using AndreGoepel.Core;
+using AndreGoepel.Marten.Identity.Services;
 using Microsoft.AspNetCore.Identity;
 
 namespace AndreGoepel.Marten.Identity.Users;
@@ -27,38 +28,23 @@ public sealed class UserInvitationService(
     IIdentityAuthorizer authorizer
 )
 {
-    private static IdentityResult NotAuthorized() =>
-        IdentityResult.Failed(
-            new IdentityError
-            {
-                Code = IdentityErrorCodes.NotAuthorized,
-                Description = "Inviting a user requires administrator authority.",
-            }
-        );
-
-    private static IdentityResult Failure(string code, string description) =>
-        IdentityResult.Failed(new IdentityError { Code = code, Description = description });
+    private const string NotAuthorizedMessage = "Inviting a user requires administrator authority.";
 
     /// <summary>
     /// Creates a passwordless, unconfirmed account for <paramref name="email"/>, assigns
     /// <paramref name="roles"/>, and returns the invitation token to embed in the link.
     /// </summary>
-    public async Task<UserInvitationResult> InviteAsync(
+    public async Task<Result<UserInvitationDetails>> InviteAsync(
         string email,
         IEnumerable<string>? roles = null,
         CancellationToken cancellationToken = default
     )
     {
         if (!await authorizer.IsCurrentUserAdministratorAsync(cancellationToken))
-            return UserInvitationResult.Failed(NotAuthorized());
+            return Result.Fail<UserInvitationDetails>(NotAuthorizedMessage);
 
         if (await userManager.FindByEmailAsync(email) is not null)
-            return UserInvitationResult.Failed(
-                Failure(
-                    IdentityErrorCodes.DuplicateEmail,
-                    $"An account already exists for {email}."
-                )
-            );
+            return Result.Fail<UserInvitationDetails>($"An account already exists for {email}.");
 
         // No password argument: the account is created with a null password hash, so it
         // cannot be signed in to until the invitee redeems the link and sets one. Leaving
@@ -69,43 +55,40 @@ public async Task<UserInvitationResult> InviteAsync(
 
         var createResult = await userManager.CreateAsync(user);
         if (!createResult.Succeeded)
-            return UserInvitationResult.Failed(createResult);
+            return Result.Fail<UserInvitationDetails>(Describe(createResult));
 
         var roleList = roles?.ToArray() ?? [];
         foreach (var role in roleList)
         {
             var roleResult = await userStore.AddToRoleAsync(user, role, cancellationToken);
             if (!roleResult.Succeeded)
-                return UserInvitationResult.Failed(roleResult);
+                return Result.Fail<UserInvitationDetails>(Describe(roleResult));
         }
 
-        return UserInvitationResult.Success(user, await GenerateTokenAsync(user));
+        return Result.Ok(new UserInvitationDetails(user, await GenerateTokenAsync(user)));
     }
 
     /// <summary>
     /// Issues a fresh invitation token for an account that was invited but has not been
     /// claimed yet, for when the first email is lost or expires.
     /// </summary>
-    public async Task<UserInvitationResult> ResendAsync(
+    public async Task<Result<UserInvitationDetails>> ResendAsync(
         User user,
         CancellationToken cancellationToken = default
     )
     {
         if (!await authorizer.IsCurrentUserAdministratorAsync(cancellationToken))
-            return UserInvitationResult.Failed(NotAuthorized());
+            return Result.Fail<UserInvitationDetails>(NotAuthorizedMessage);
 
         // Refuse to re-issue against a claimed account. Without this, "resend invitation"
         // would amount to a password reset for an active colleague that skips their
         // mailbox check: it would mint a link setting their password on demand.
         if (!IsPending(user))
-            return UserInvitationResult.Failed(
-                Failure(
-                    IdentityErrorCodes.InvitationAlreadyAccepted,
-                    "This account has already been set up; send a password reset instead."
-                )
+            return Result.Fail<UserInvitationDetails>(
+                "This account has already been set up; send a password reset instead."
             );
 
-        return UserInvitationResult.Success(user, await GenerateTokenAsync(user));
+        return Result.Ok(new UserInvitationDetails(user, await GenerateTokenAsync(user)));
     }
 
     /// <summary>
@@ -121,29 +104,11 @@ private Task<string> GenerateTokenAsync(User user) =>
             UserInvitationTokenProvider.ProviderName,
             UserInvitationTokenProvider.Purpose
         );
-}
-
-/// <summary>Outcome of an invitation attempt: the created user and its token on success.</summary>
-public sealed record UserInvitationResult
-{
-    private UserInvitationResult() { }
 
-    public bool Succeeded { get; private init; }
-    public IdentityResult Result { get; private init; } = IdentityResult.Success;
-    public User? User { get; private init; }
-    public string? Token { get; private init; }
-
-    /// <summary>The failure descriptions, joined for display.</summary>
-    public string ErrorMessage => string.Join(", ", Result.Errors.Select(e => e.Description));
-
-    internal static UserInvitationResult Success(User user, string token) =>
-        new()
-        {
-            Succeeded = true,
-            User = user,
-            Token = token,
-        };
-
-    internal static UserInvitationResult Failed(IdentityResult result) =>
-        new() { Succeeded = false, Result = result };
+    /// <summary>Joins an <see cref="IdentityResult"/>'s failure descriptions into one message.</summary>
+    private static string Describe(IdentityResult result) =>
+        string.Join(", ", result.Errors.Select(e => e.Description));
 }
+
+/// <summary>The created user and its invitation token, on a successful invite or resend.</summary>
+public sealed record UserInvitationDetails(User User, string Token);
diff --git a/src/AndreGoepel.Marten.Identity/packages.lock.json b/src/AndreGoepel.Marten.Identity/packages.lock.json
index 1b53e6e..100279e 100644
--- a/src/AndreGoepel.Marten.Identity/packages.lock.json
+++ b/src/AndreGoepel.Marten.Identity/packages.lock.json
@@ -2,6 +2,12 @@
   "version": 2,
   "dependencies": {
     "net10.0": {
+      "AndreGoepel.Core": {
+        "type": "Direct",
+        "requested": "[1.0.1, )",
+        "resolved": "1.0.1",
+        "contentHash": "jA27iMianyxUdrCtz5b6KxZOYxXlhZqkxDVKD6sed1sDCHF1upfV28CnczJ6kYPcrqJNj9+cDaxMWPlNvDkjcA=="
+      },
       "AndreGoepel.Marten.Configuration": {
         "type": "Direct",
         "requested": "[1.0.1, )",
diff --git a/tests/AndreGoepel.Marten.Identity.Blazor.Tests/packages.lock.json b/tests/AndreGoepel.Marten.Identity.Blazor.Tests/packages.lock.json
index 8a567cb..251bddb 100644
--- a/tests/AndreGoepel.Marten.Identity.Blazor.Tests/packages.lock.json
+++ b/tests/AndreGoepel.Marten.Identity.Blazor.Tests/packages.lock.json
@@ -370,6 +370,7 @@
       "andregoepel.marten.identity": {
         "type": "Project",
         "dependencies": {
+          "AndreGoepel.Core": "[1.0.1, )",
           "AndreGoepel.Marten.Configuration": "[1.0.1, )",
           "AndreGoepel.Marten.Identity.Abstractions": "[1.8.0, )",
           "Marten": "[9.19.0, )",
@@ -390,6 +391,12 @@
           "Radzen.Blazor": "[11.1.7, )"
         }
       },
+      "AndreGoepel.Core": {
+        "type": "CentralTransitive",
+        "requested": "[1.0.1, )",
+        "resolved": "1.0.1",
+        "contentHash": "jA27iMianyxUdrCtz5b6KxZOYxXlhZqkxDVKD6sed1sDCHF1upfV28CnczJ6kYPcrqJNj9+cDaxMWPlNvDkjcA=="
+      },
       "AndreGoepel.Design.Blazor": {
         "type": "CentralTransitive",
         "requested": "[1.4.2, )",
diff --git a/tests/AndreGoepel.Marten.Identity.IntegrationTests/Users/UserInvitationServiceTests.cs b/tests/AndreGoepel.Marten.Identity.IntegrationTests/Users/UserInvitationServiceTests.cs
index 8ee90af..0a46168 100644
--- a/tests/AndreGoepel.Marten.Identity.IntegrationTests/Users/UserInvitationServiceTests.cs
+++ b/tests/AndreGoepel.Marten.Identity.IntegrationTests/Users/UserInvitationServiceTests.cs
@@ -46,8 +46,8 @@ public async Task InviteAsync_AnonymousActor_ReturnsNotAuthorized()
         var result = await invitations.InviteAsync("new@example.com", cancellationToken: Ct);
 
         // Assert
-        Assert.False(result.Succeeded);
-        Assert.Contains(result.Result.Errors, e => e.Code == "NotAuthorized");
+        Assert.False(result.IsSuccess);
+        Assert.Contains("administrator authority", result.Error);
     }
 
     [Fact]
@@ -60,8 +60,8 @@ public async Task InviteAsync_NonAdminActor_ReturnsNotAuthorized()
         var result = await invitations.InviteAsync("new@example.com", cancellationToken: Ct);
 
         // Assert
-        Assert.False(result.Succeeded);
-        Assert.Contains(result.Result.Errors, e => e.Code == "NotAuthorized");
+        Assert.False(result.IsSuccess);
+        Assert.Contains("administrator authority", result.Error);
         Assert.Null(await FindAsync("new@example.com"));
     }
 
@@ -76,8 +76,8 @@ public async Task InviteAsync_AdminActor_CreatesPasswordlessUnconfirmedUserWithT
         var result = await invitations.InviteAsync("new@example.com", cancellationToken: Ct);
 
         // Assert
-        Assert.True(result.Succeeded);
-        Assert.False(string.IsNullOrEmpty(result.Token));
+        Assert.True(result.IsSuccess);
+        Assert.False(string.IsNullOrEmpty(result.Value!.Token));
 
         var created = await FindAsync("new@example.com");
         Assert.NotNull(created);
@@ -102,7 +102,7 @@ public async Task InviteAsync_WithRoles_AssignsThem()
         );
 
         // Assert
-        Assert.True(result.Succeeded);
+        Assert.True(result.IsSuccess);
         var created = await users.FindByEmailAsync("new@example.com");
         Assert.Contains("Member", await users.GetRolesAsync(created!));
     }
@@ -119,8 +119,8 @@ public async Task InviteAsync_DuplicateEmail_Fails()
         var again = await invitations.InviteAsync("dupe@example.com", cancellationToken: Ct);
 
         // Assert
-        Assert.False(again.Succeeded);
-        Assert.Contains(again.Result.Errors, e => e.Code == "DuplicateEmail");
+        Assert.False(again.IsSuccess);
+        Assert.Contains("dupe@example.com", again.Error);
     }
 
     [Fact]
@@ -136,8 +136,8 @@ public async Task ResendAsync_PendingInvitation_IssuesFreshToken()
         var resend = await invitations.ResendAsync(user!, Ct);
 
         // Assert
-        Assert.True(resend.Succeeded);
-        Assert.False(string.IsNullOrEmpty(resend.Token));
+        Assert.True(resend.IsSuccess);
+        Assert.False(string.IsNullOrEmpty(resend.Value!.Token));
     }
 
     [Fact]
@@ -158,8 +158,8 @@ public async Task ResendAsync_AlreadyAcceptedAccount_IsRefused()
         var resend = await invitations.ResendAsync(claimed!, Ct);
 
         // Assert
-        Assert.False(resend.Succeeded);
-        Assert.Contains(resend.Result.Errors, e => e.Code == "InvitationAlreadyAccepted");
+        Assert.False(resend.IsSuccess);
+        Assert.Contains("already been set up", resend.Error);
     }
 
     #region Harness
diff --git a/tests/AndreGoepel.Marten.Identity.IntegrationTests/packages.lock.json b/tests/AndreGoepel.Marten.Identity.IntegrationTests/packages.lock.json
index 6090b2b..a58f01a 100644
--- a/tests/AndreGoepel.Marten.Identity.IntegrationTests/packages.lock.json
+++ b/tests/AndreGoepel.Marten.Identity.IntegrationTests/packages.lock.json
@@ -417,6 +417,7 @@
       "andregoepel.marten.identity": {
         "type": "Project",
         "dependencies": {
+          "AndreGoepel.Core": "[1.0.1, )",
           "AndreGoepel.Marten.Configuration": "[1.0.1, )",
           "AndreGoepel.Marten.Identity.Abstractions": "[1.8.0, )",
           "Marten": "[9.19.0, )",
@@ -437,6 +438,12 @@
           "Radzen.Blazor": "[11.1.7, )"
         }
       },
+      "AndreGoepel.Core": {
+        "type": "CentralTransitive",
+        "requested": "[1.0.1, )",
+        "resolved": "1.0.1",
+        "contentHash": "jA27iMianyxUdrCtz5b6KxZOYxXlhZqkxDVKD6sed1sDCHF1upfV28CnczJ6kYPcrqJNj9+cDaxMWPlNvDkjcA=="
+      },
       "AndreGoepel.Design.Blazor": {
         "type": "CentralTransitive",
         "requested": "[1.4.2, )",
diff --git a/tests/AndreGoepel.Marten.Identity.Tests/packages.lock.json b/tests/AndreGoepel.Marten.Identity.Tests/packages.lock.json
index 0a3ba31..15127bb 100644
--- a/tests/AndreGoepel.Marten.Identity.Tests/packages.lock.json
+++ b/tests/AndreGoepel.Marten.Identity.Tests/packages.lock.json
@@ -631,6 +631,7 @@
       "andregoepel.marten.identity": {
         "type": "Project",
         "dependencies": {
+          "AndreGoepel.Core": "[1.0.1, )",
           "AndreGoepel.Marten.Configuration": "[1.0.1, )",
           "AndreGoepel.Marten.Identity.Abstractions": "[1.8.0, )",
           "Marten": "[9.19.0, )",
@@ -641,6 +642,12 @@
       "andregoepel.marten.identity.abstractions": {
         "type": "Project"
       },
+      "AndreGoepel.Core": {
+        "type": "CentralTransitive",
+        "requested": "[1.0.1, )",
+        "resolved": "1.0.1",
+        "contentHash": "jA27iMianyxUdrCtz5b6KxZOYxXlhZqkxDVKD6sed1sDCHF1upfV28CnczJ6kYPcrqJNj9+cDaxMWPlNvDkjcA=="
+      },
       "AndreGoepel.Marten.Configuration": {
         "type": "CentralTransitive",
         "requested": "[1.0.1, )",