diff --git a/src/modules/Elsa.Labels/Endpoints/Labels/Update/Mappers.cs b/src/modules/Elsa.Labels/Endpoints/Labels/Update/Mappers.cs
index bc1ca9181..ce8eb9177 100644
--- a/src/modules/Elsa.Labels/Endpoints/Labels/Update/Mappers.cs
+++ b/src/modules/Elsa.Labels/Endpoints/Labels/Update/Mappers.cs
@@ -26,7 +26,6 @@ internal class LabelMapper : Mapper<Request, Response, Label>
         e.Color = r.Color?.Trim();
         e.Description = r.Description?.Trim();
         e.Name = r.Name.Trim();
-        e.NormalizedName = r.Name.ToLowerInvariant();
         return e;
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Labels/Entities/Label.cs b/src/modules/Elsa.Labels/Entities/Label.cs
index f6dd24e22..2f2ae4b0d 100644
--- a/src/modules/Elsa.Labels/Entities/Label.cs
+++ b/src/modules/Elsa.Labels/Entities/Label.cs
@@ -7,6 +7,12 @@ namespace Elsa.Labels.Entities;
 /// </summary>
 public class Label : Entity
 {
+    /// <summary>
+    /// Shared maximum for <see cref="Name"/> and <see cref="NormalizedName"/>.
+    /// Matches the MySQL unique-index limit that every provider's schema must honor.
+    /// </summary>
+    public const int NameMaxLength = 255;
+
     private string _name = default!;
 
     public string Name
@@ -14,6 +20,13 @@ public class Label : Entity
         get => _name;
         set
         {
+            if (value.Length > NameMaxLength)
+            {
+                throw new ArgumentException(
+                    $"Label name cannot exceed {NameMaxLength} characters.",
+                    nameof(Name));
+            }
+
             _name = value;
             NormalizedName = value.ToLowerInvariant();
         }
diff --git a/src/modules/Elsa.Labels/Services/InMemoryLabelStore.cs b/src/modules/Elsa.Labels/Services/InMemoryLabelStore.cs
index a5e64795f..242443a72 100644
--- a/src/modules/Elsa.Labels/Services/InMemoryLabelStore.cs
+++ b/src/modules/Elsa.Labels/Services/InMemoryLabelStore.cs
@@ -38,9 +38,14 @@ public class InMemoryLabelStore : ILabelStore
     /// <inheritdoc />
     public Task SaveAsync(Label record, CancellationToken cancellationToken = default)
     {
-        ApplyCurrentTenant(record);
         lock (_labelStore.Sync)
+        {
+            ApplyCurrentTenant(record);
+            SyncNormalizedName(record);
+            EnsureNormalizedNameAvailable(record, [record]);
             _labelStore.Save(record, x => x.Id);
+        }
+
         return Task.CompletedTask;
     }
 
@@ -49,11 +54,20 @@ public class InMemoryLabelStore : ILabelStore
     {
         var list = records.ToList();
 
-        foreach (var record in list)
-            ApplyCurrentTenant(record);
-
         lock (_labelStore.Sync)
+        {
+            foreach (var record in list)
+            {
+                ApplyCurrentTenant(record);
+                SyncNormalizedName(record);
+            }
+
+            foreach (var record in list)
+                EnsureNormalizedNameAvailable(record, list);
+
             _labelStore.SaveMany(list, x => x.Id);
+        }
+
         return Task.CompletedTask;
     }
 
@@ -90,7 +104,8 @@ public class InMemoryLabelStore : ILabelStore
     /// <inheritdoc />
     public Task<Label?> FindByIdAsync(string id, CancellationToken cancellationToken = default)
     {
-        return Task.FromResult(FindVisibleLabel(id));
+        var found = FindVisibleLabel(id);
+        return Task.FromResult(found is null ? null : Clone(found));
     }
 
     /// <inheritdoc />
@@ -98,20 +113,38 @@ public class InMemoryLabelStore : ILabelStore
     {
         var query = _labelStore.List().AsQueryable().WhereVisibleToTenant(CurrentTenantId).OrderBy(x => x.Name);
         var page = query.ToPage(pageArgs);
-        return Task.FromResult(page);
+        return Task.FromResult(Page.Of(page.Items.Select(Clone).ToList(), page.TotalCount));
     }
 
     /// <inheritdoc />
     public Task<IEnumerable<Label>> FindManyByIdAsync(IEnumerable<string> ids, CancellationToken cancellationToken)
     {
         var idList = ids.ToList();
-        var records = _labelStore.Query(query => query.WhereVisibleToTenant(CurrentTenantId).Where(x => idList.Contains(x.Id)));
-        return Task.FromResult(records);
+        var records = _labelStore.Query(query => query.WhereVisibleToTenant(CurrentTenantId).Where(x => idList.Contains(x.Id)))
+            .Select(Clone)
+            .ToList();
+        return Task.FromResult<IEnumerable<Label>>(records);
     }
 
     private Label? FindVisibleLabel(string id) =>
         _labelStore.Query(query => query.WhereVisibleToTenant(CurrentTenantId).Where(x => x.Id == id)).FirstOrDefault();
 
+    /// <summary>
+    /// Clone-on-read, matching Memory identity stores. Labels.Update does Find → mutate
+    /// Name (which writes NormalizedName) → Save. Without a copy, a rejected rename
+    /// would already have mutated the stored row.
+    /// </summary>
+    private static Label Clone(Label label) =>
+        new()
+        {
+            Id = label.Id,
+            TenantId = label.TenantId,
+            Name = label.Name,
+            NormalizedName = label.NormalizedName,
+            Description = label.Description,
+            Color = label.Color
+        };
+
     private bool IsVisible(Entity entity) => TenantVisibility.IsVisible(entity.TenantId, CurrentTenantId);
 
     private string CurrentTenantId => _tenantAccessor?.TenantId ?? Tenant.DefaultTenantId;
@@ -123,4 +156,36 @@ public class InMemoryLabelStore : ILabelStore
 
         entity.TenantId ??= _tenantAccessor.TenantId;
     }
+
+    private static void SyncNormalizedName(Label record) =>
+        record.NormalizedName = record.Name.ToLowerInvariant();
+
+    /// <summary>
+    /// Memory counterpart of the EF unique index on <c>(TenantId, NormalizedName)</c>.
+    /// Same-Id upserts are allowed so a row can rename itself. Incoming batch rows
+    /// replace same-Id store rows, so those store rows are ignored here.
+    /// </summary>
+    private void EnsureNormalizedNameAvailable(Label record, IReadOnlyCollection<Label> batch)
+    {
+        var batchIds = batch.Select(x => x.Id).ToHashSet();
+        var existing = _labelStore.Find(candidate =>
+            candidate.TenantId == record.TenantId
+            && candidate.Id != record.Id
+            && !batchIds.Contains(candidate.Id)
+            && candidate.NormalizedName == record.NormalizedName);
+
+        if (existing is not null)
+            throw DuplicateNormalizedName(record);
+
+        if (batch.Any(other =>
+                other.Id != record.Id
+                && other.TenantId == record.TenantId
+                && other.NormalizedName == record.NormalizedName))
+        {
+            throw DuplicateNormalizedName(record);
+        }
+    }
+
+    private static InvalidOperationException DuplicateNormalizedName(Label record) =>
+        new($"A label already exists with normalized name '{record.NormalizedName}' in tenant '{record.TenantId}'.");
 }
diff --git a/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/20260913133332_PerTenantLabelUniqueness.Designer.cs b/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/20260913133332_PerTenantLabelUniqueness.Designer.cs
new file mode 100644
index 000000000..3959d1610
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/20260913133332_PerTenantLabelUniqueness.Designer.cs
@@ -0,0 +1,100 @@
+// <auto-generated />
+using Elsa.Persistence.EFCore.Modules.Labels;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.MySql.Migrations.Labels
+{
+    [DbContext(typeof(LabelsElsaDbContext))]
+    [Migration("20260913133332_PerTenantLabelUniqueness")]
+    partial class PerTenantLabelUniqueness
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasDefaultSchema("Elsa")
+                .HasAnnotation("ProductVersion", "9.0.17")
+                .HasAnnotation("Relational:MaxIdentifierLength", 64);
+
+            MySqlModelBuilderExtensions.AutoIncrementColumns(modelBuilder);
+
+            modelBuilder.Entity("Elsa.Labels.Entities.Label", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("varchar(255)");
+
+                    b.Property<string>("Color")
+                        .HasColumnType("longtext");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("longtext");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("varchar(255)");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("varchar(255)");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("varchar(255)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName");
+
+                    b.ToTable("Labels", "Elsa");
+                });
+
+            modelBuilder.Entity("Elsa.Labels.Entities.WorkflowDefinitionLabel", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("varchar(255)");
+
+                    b.Property<string>("LabelId")
+                        .IsRequired()
+                        .HasColumnType("varchar(255)");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("varchar(255)");
+
+                    b.Property<string>("WorkflowDefinitionId")
+                        .IsRequired()
+                        .HasColumnType("varchar(255)");
+
+                    b.Property<string>("WorkflowDefinitionVersionId")
+                        .IsRequired()
+                        .HasColumnType("varchar(255)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LabelId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_LabelId");
+
+                    b.HasIndex("TenantId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_TenantId");
+
+                    b.HasIndex("WorkflowDefinitionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionId");
+
+                    b.HasIndex("WorkflowDefinitionVersionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionVersionId");
+
+                    b.ToTable("WorkflowDefinitionLabels", "Elsa");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/20260913133332_PerTenantLabelUniqueness.cs b/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/20260913133332_PerTenantLabelUniqueness.cs
new file mode 100644
index 000000000..447abd792
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/20260913133332_PerTenantLabelUniqueness.cs
@@ -0,0 +1,172 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.MySql.Migrations.Labels
+{
+    /// <inheritdoc />
+    public partial class PerTenantLabelUniqueness : Migration
+    {
+        private readonly Elsa.Persistence.EFCore.IElsaDbContextSchema _schema;
+
+        /// <inheritdoc />
+        public PerTenantLabelUniqueness(Elsa.Persistence.EFCore.IElsaDbContextSchema schema)
+        {
+            _schema = schema;
+        }
+
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Default tenant is "" (not null). Stamp leftover nulls so the unique index covers them.
+            migrationBuilder.Sql($"""
+                UPDATE `{_schema.Schema}`.`Labels`
+                SET `TenantId` = ''
+                WHERE `TenantId` IS NULL;
+                """);
+
+            // No silent dedupe. List leftover keys and abort; operators must resolve them before upgrading.
+            // SIGNAL MESSAGE_TEXT is limited to 128 characters, so the listed keys are truncated.
+            migrationBuilder.Sql($"""
+                SET @duplicate_keys := (
+                    SELECT GROUP_CONCAT(CONCAT('(', IFNULL(`TenantId`, '<null>'), ', ', `NormalizedName`, ')') SEPARATOR '; ')
+                    FROM (
+                        SELECT `TenantId`, `NormalizedName`
+                        FROM `{_schema.Schema}`.`Labels`
+                        GROUP BY `TenantId`, `NormalizedName`
+                        HAVING COUNT(*) > 1
+                    ) AS Duplicates
+                );
+
+                SET @sql := IF(
+                    @duplicate_keys IS NOT NULL,
+                    CONCAT(
+                        'SIGNAL SQLSTATE ''45000'' SET MESSAGE_TEXT = ''',
+                        LEFT(REPLACE(CONCAT(
+                            'Duplicate keys. Resolve before upgrade: ',
+                            @duplicate_keys
+                        ), '''', ''), 128),
+                        ''''
+                    ),
+                    'SELECT 1'
+                );
+                PREPARE stmt FROM @sql;
+                EXECUTE stmt;
+                DEALLOCATE PREPARE stmt;
+                """);
+
+            // Name/NormalizedName are not truncated; list over-length Ids and abort before ALTER.
+            migrationBuilder.Sql($"""
+                SET @over_length_ids := (
+                    SELECT GROUP_CONCAT(`Id` SEPARATOR ', ')
+                    FROM `{_schema.Schema}`.`Labels`
+                    WHERE CHAR_LENGTH(`Name`) > 255 OR CHAR_LENGTH(`NormalizedName`) > 255
+                );
+
+                SET @sql := IF(
+                    @over_length_ids IS NOT NULL,
+                    CONCAT(
+                        'SIGNAL SQLSTATE ''45000'' SET MESSAGE_TEXT = ''',
+                        LEFT(REPLACE(CONCAT(
+                            'Over-length Name/NormalizedName. Shorten before upgrade. Ids: ',
+                            @over_length_ids
+                        ), '''', ''), 128),
+                        ''''
+                    ),
+                    'SELECT 1'
+                );
+                PREPARE stmt FROM @sql;
+                EXECUTE stmt;
+                DEALLOCATE PREPARE stmt;
+                """);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "TenantId",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "varchar(255)",
+                nullable: true,
+                oldClrType: typeof(string),
+                oldType: "longtext",
+                oldNullable: true)
+                .Annotation("MySql:CharSet", "utf8mb4")
+                .OldAnnotation("MySql:CharSet", "utf8mb4");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Name",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "varchar(255)",
+                maxLength: 255,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "longtext")
+                .Annotation("MySql:CharSet", "utf8mb4")
+                .OldAnnotation("MySql:CharSet", "utf8mb4");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "varchar(255)",
+                maxLength: 255,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "longtext")
+                .Annotation("MySql:CharSet", "utf8mb4")
+                .OldAnnotation("MySql:CharSet", "utf8mb4");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                columns: new[] { "TenantId", "NormalizedName" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "TenantId",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "longtext",
+                nullable: true,
+                oldClrType: typeof(string),
+                oldType: "varchar(255)",
+                oldNullable: true)
+                .Annotation("MySql:CharSet", "utf8mb4")
+                .OldAnnotation("MySql:CharSet", "utf8mb4");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "longtext",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "varchar(255)",
+                oldMaxLength: 255)
+                .Annotation("MySql:CharSet", "utf8mb4")
+                .OldAnnotation("MySql:CharSet", "utf8mb4");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Name",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "longtext",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "varchar(255)",
+                oldMaxLength: 255)
+                .Annotation("MySql:CharSet", "utf8mb4")
+                .OldAnnotation("MySql:CharSet", "utf8mb4");
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs b/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
index 769936df4..8c8b4c052 100644
--- a/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
+++ b/src/modules/Elsa.Persistence.EFCore.MySql/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
@@ -17,7 +17,7 @@ namespace Elsa.Persistence.EFCore.MySql.Migrations.Labels
 #pragma warning disable 612, 618
             modelBuilder
                 .HasDefaultSchema("Elsa")
-                .HasAnnotation("ProductVersion", "8.0.12")
+                .HasAnnotation("ProductVersion", "9.0.17")
                 .HasAnnotation("Relational:MaxIdentifierLength", 64);
 
             MySqlModelBuilderExtensions.AutoIncrementColumns(modelBuilder);
@@ -35,17 +35,23 @@ namespace Elsa.Persistence.EFCore.MySql.Migrations.Labels
 
                     b.Property<string>("Name")
                         .IsRequired()
-                        .HasColumnType("longtext");
+                        .HasMaxLength(255)
+                        .HasColumnType("varchar(255)");
 
                     b.Property<string>("NormalizedName")
                         .IsRequired()
-                        .HasColumnType("longtext");
+                        .HasMaxLength(255)
+                        .HasColumnType("varchar(255)");
 
                     b.Property<string>("TenantId")
-                        .HasColumnType("longtext");
+                        .HasColumnType("varchar(255)");
 
                     b.HasKey("Id");
 
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName");
+
                     b.ToTable("Labels", "Elsa");
                 });
 
diff --git a/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/20260913133340_PerTenantLabelUniqueness.Designer.cs b/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/20260913133340_PerTenantLabelUniqueness.Designer.cs
new file mode 100644
index 000000000..3cd932f2d
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/20260913133340_PerTenantLabelUniqueness.Designer.cs
@@ -0,0 +1,101 @@
+// <auto-generated />
+using Elsa.Persistence.EFCore.Modules.Labels;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Oracle.EntityFrameworkCore.Metadata;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.Oracle.Migrations.Labels
+{
+    [DbContext(typeof(LabelsElsaDbContext))]
+    [Migration("20260913133340_PerTenantLabelUniqueness")]
+    partial class PerTenantLabelUniqueness
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasDefaultSchema("Elsa")
+                .HasAnnotation("ProductVersion", "9.0.17")
+                .HasAnnotation("Relational:MaxIdentifierLength", 128);
+
+            OracleModelBuilderExtensions.UseIdentityColumns(modelBuilder);
+
+            modelBuilder.Entity("Elsa.Labels.Entities.Label", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("NVARCHAR2(450)");
+
+                    b.Property<string>("Color")
+                        .HasColumnType("NVARCHAR2(2000)");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("NVARCHAR2(2000)");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("NVARCHAR2(255)");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("NVARCHAR2(255)");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("NVARCHAR2(450)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName")
+                        .HasFilter("\"TenantId\" IS NOT NULL");
+
+                    b.ToTable("Labels", "Elsa");
+                });
+
+            modelBuilder.Entity("Elsa.Labels.Entities.WorkflowDefinitionLabel", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("NVARCHAR2(450)");
+
+                    b.Property<string>("LabelId")
+                        .IsRequired()
+                        .HasColumnType("NVARCHAR2(450)");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("NVARCHAR2(450)");
+
+                    b.Property<string>("WorkflowDefinitionId")
+                        .IsRequired()
+                        .HasColumnType("NVARCHAR2(450)");
+
+                    b.Property<string>("WorkflowDefinitionVersionId")
+                        .IsRequired()
+                        .HasColumnType("NVARCHAR2(450)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LabelId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_LabelId");
+
+                    b.HasIndex("TenantId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_TenantId");
+
+                    b.HasIndex("WorkflowDefinitionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionId");
+
+                    b.HasIndex("WorkflowDefinitionVersionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionVersionId");
+
+                    b.ToTable("WorkflowDefinitionLabels", "Elsa");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/20260913133340_PerTenantLabelUniqueness.cs b/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/20260913133340_PerTenantLabelUniqueness.cs
new file mode 100644
index 000000000..be006d2bf
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/20260913133340_PerTenantLabelUniqueness.cs
@@ -0,0 +1,174 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.Oracle.Migrations.Labels
+{
+    /// <inheritdoc />
+    public partial class PerTenantLabelUniqueness : Migration
+    {
+        private readonly Elsa.Persistence.EFCore.IElsaDbContextSchema _schema;
+
+        /// <inheritdoc />
+        public PerTenantLabelUniqueness(Elsa.Persistence.EFCore.IElsaDbContextSchema schema)
+        {
+            _schema = schema;
+        }
+
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Default tenant is "" (not null). Stamp leftover nulls so the filtered unique
+            // index (TenantId IS NOT NULL) covers them. Duplicates are not deleted.
+            migrationBuilder.Sql($"""
+                UPDATE "{_schema.Schema}"."Labels"
+                SET "TenantId" = ''
+                WHERE "TenantId" IS NULL;
+                """);
+
+            // No silent dedupe. List leftover keys and abort; operators must resolve them before upgrading.
+            migrationBuilder.Sql($"""
+                DECLARE
+                    duplicate_keys VARCHAR2(4000);
+                    duplicate_count NUMBER;
+                BEGIN
+                    SELECT COUNT(*)
+                    INTO duplicate_count
+                    FROM (
+                        SELECT "TenantId", "NormalizedName"
+                        FROM "{_schema.Schema}"."Labels"
+                        GROUP BY "TenantId", "NormalizedName"
+                        HAVING COUNT(*) > 1
+                    );
+
+                    IF duplicate_count > 0 THEN
+                        SELECT LISTAGG('(' || NVL("TenantId", '<null>') || ', ' || "NormalizedName" || ')', '; ' ON OVERFLOW TRUNCATE)
+                            WITHIN GROUP (ORDER BY "NormalizedName")
+                        INTO duplicate_keys
+                        FROM (
+                            SELECT "TenantId", "NormalizedName"
+                            FROM "{_schema.Schema}"."Labels"
+                            GROUP BY "TenantId", "NormalizedName"
+                            HAVING COUNT(*) > 1
+                        );
+
+                        RAISE_APPLICATION_ERROR(
+                            -20001,
+                            SUBSTR(
+                                'Cannot create unique index IX_Label_TenantId_NormalizedName because leftover duplicate (TenantId, NormalizedName) rows exist. Operators must resolve leftover (TenantId, NormalizedName) rows before upgrade. Duplicate keys: ' || duplicate_keys,
+                                1,
+                                2048
+                            )
+                        );
+                    END IF;
+                END;
+                """);
+
+            // Name/NormalizedName are not truncated; list over-length Ids and abort before ALTER.
+            migrationBuilder.Sql($"""
+                DECLARE
+                    over_length_ids VARCHAR2(4000);
+                    over_length_count NUMBER;
+                BEGIN
+                    SELECT COUNT(*)
+                    INTO over_length_count
+                    FROM "{_schema.Schema}"."Labels"
+                    WHERE LENGTH("Name") > 255 OR LENGTH("NormalizedName") > 255;
+
+                    IF over_length_count > 0 THEN
+                        SELECT LISTAGG("Id", ', ' ON OVERFLOW TRUNCATE) WITHIN GROUP (ORDER BY "Id")
+                        INTO over_length_ids
+                        FROM "{_schema.Schema}"."Labels"
+                        WHERE LENGTH("Name") > 255 OR LENGTH("NormalizedName") > 255;
+
+                        RAISE_APPLICATION_ERROR(
+                            -20002,
+                            SUBSTR(
+                                'Cannot alter Labels.Name / Labels.NormalizedName to NVARCHAR2(255) because leftover rows exceed 255 characters. Operators must shorten or remove those rows before upgrade. Over-length Ids: ' || over_length_ids,
+                                1,
+                                2048
+                            )
+                        );
+                    END IF;
+                END;
+                """);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "TenantId",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "NVARCHAR2(450)",
+                nullable: true,
+                oldClrType: typeof(string),
+                oldType: "NVARCHAR2(2000)",
+                oldNullable: true);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Name",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "NVARCHAR2(255)",
+                maxLength: 255,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "NVARCHAR2(2000)");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "NVARCHAR2(255)",
+                maxLength: 255,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "NVARCHAR2(2000)");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                columns: new[] { "TenantId", "NormalizedName" },
+                unique: true,
+                filter: "\"TenantId\" IS NOT NULL");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "TenantId",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "NVARCHAR2(2000)",
+                nullable: true,
+                oldClrType: typeof(string),
+                oldType: "NVARCHAR2(450)",
+                oldNullable: true);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "NVARCHAR2(2000)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "NVARCHAR2(255)",
+                oldMaxLength: 255);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Name",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "NVARCHAR2(2000)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "NVARCHAR2(255)",
+                oldMaxLength: 255);
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs b/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
index 3e8199e13..6628721f7 100644
--- a/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
+++ b/src/modules/Elsa.Persistence.EFCore.Oracle/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
@@ -17,7 +17,7 @@ namespace Elsa.Persistence.EFCore.Oracle.Migrations.Labels
 #pragma warning disable 612, 618
             modelBuilder
                 .HasDefaultSchema("Elsa")
-                .HasAnnotation("ProductVersion", "8.0.12")
+                .HasAnnotation("ProductVersion", "9.0.17")
                 .HasAnnotation("Relational:MaxIdentifierLength", 128);
 
             OracleModelBuilderExtensions.UseIdentityColumns(modelBuilder);
@@ -35,17 +35,24 @@ namespace Elsa.Persistence.EFCore.Oracle.Migrations.Labels
 
                     b.Property<string>("Name")
                         .IsRequired()
-                        .HasColumnType("NVARCHAR2(2000)");
+                        .HasMaxLength(255)
+                        .HasColumnType("NVARCHAR2(255)");
 
                     b.Property<string>("NormalizedName")
                         .IsRequired()
-                        .HasColumnType("NVARCHAR2(2000)");
+                        .HasMaxLength(255)
+                        .HasColumnType("NVARCHAR2(255)");
 
                     b.Property<string>("TenantId")
-                        .HasColumnType("NVARCHAR2(2000)");
+                        .HasColumnType("NVARCHAR2(450)");
 
                     b.HasKey("Id");
 
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName")
+                        .HasFilter("\"TenantId\" IS NOT NULL");
+
                     b.ToTable("Labels", "Elsa");
                 });
 
diff --git a/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/20260913133325_PerTenantLabelUniqueness.Designer.cs b/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/20260913133325_PerTenantLabelUniqueness.Designer.cs
new file mode 100644
index 000000000..9972d6141
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/20260913133325_PerTenantLabelUniqueness.Designer.cs
@@ -0,0 +1,100 @@
+// <auto-generated />
+using Elsa.Persistence.EFCore.Modules.Labels;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.PostgreSql.Migrations.Labels
+{
+    [DbContext(typeof(LabelsElsaDbContext))]
+    [Migration("20260913133325_PerTenantLabelUniqueness")]
+    partial class PerTenantLabelUniqueness
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasDefaultSchema("Elsa")
+                .HasAnnotation("ProductVersion", "9.0.17")
+                .HasAnnotation("Relational:MaxIdentifierLength", 63);
+
+            NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
+
+            modelBuilder.Entity("Elsa.Labels.Entities.Label", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text");
+
+                    b.Property<string>("Color")
+                        .HasColumnType("text");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("text");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("text");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("text");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("text");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName");
+
+                    b.ToTable("Labels", "Elsa");
+                });
+
+            modelBuilder.Entity("Elsa.Labels.Entities.WorkflowDefinitionLabel", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text");
+
+                    b.Property<string>("LabelId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("text");
+
+                    b.Property<string>("WorkflowDefinitionId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<string>("WorkflowDefinitionVersionId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LabelId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_LabelId");
+
+                    b.HasIndex("TenantId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_TenantId");
+
+                    b.HasIndex("WorkflowDefinitionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionId");
+
+                    b.HasIndex("WorkflowDefinitionVersionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionVersionId");
+
+                    b.ToTable("WorkflowDefinitionLabels", "Elsa");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/20260913133325_PerTenantLabelUniqueness.cs b/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/20260913133325_PerTenantLabelUniqueness.cs
new file mode 100644
index 000000000..0825e1c36
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/20260913133325_PerTenantLabelUniqueness.cs
@@ -0,0 +1,66 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.PostgreSql.Migrations.Labels
+{
+    /// <inheritdoc />
+    public partial class PerTenantLabelUniqueness : Migration
+    {
+        private readonly Elsa.Persistence.EFCore.IElsaDbContextSchema _schema;
+
+        /// <inheritdoc />
+        public PerTenantLabelUniqueness(Elsa.Persistence.EFCore.IElsaDbContextSchema schema)
+        {
+            _schema = schema;
+        }
+
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Default tenant is "" (not null). Stamp leftover nulls so the unique index covers them.
+            migrationBuilder.Sql($"""
+                UPDATE "{_schema.Schema}"."Labels"
+                SET "TenantId" = ''
+                WHERE "TenantId" IS NULL;
+                """);
+
+            // Keep provider column type (text). HasMaxLength(255) is a model annotation only.
+            // No silent dedupe. List leftover keys and abort; operators must resolve them before upgrading.
+            migrationBuilder.Sql($"""
+                DO $$
+                DECLARE keys text;
+                BEGIN
+                    SELECT string_agg(format('(%s, %s)', "TenantId", "NormalizedName"), ', ')
+                    INTO keys
+                    FROM (
+                        SELECT "TenantId", "NormalizedName"
+                        FROM "{_schema.Schema}"."Labels"
+                        GROUP BY "TenantId", "NormalizedName"
+                        HAVING COUNT(*) > 1
+                    ) d;
+
+                    IF keys IS NOT NULL THEN
+                        RAISE EXCEPTION 'Cannot apply IX_Label_TenantId_NormalizedName. Operators must resolve leftover (TenantId, NormalizedName) rows before upgrade. Duplicate keys: %', keys;
+                    END IF;
+                END $$;
+                """);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                columns: new[] { "TenantId", "NormalizedName" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels");
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs b/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
index b512db73a..70bf64b51 100644
--- a/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
+++ b/src/modules/Elsa.Persistence.EFCore.PostgreSql/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
@@ -17,7 +17,7 @@ namespace Elsa.Persistence.EFCore.PostgreSql.Migrations.Labels
 #pragma warning disable 612, 618
             modelBuilder
                 .HasDefaultSchema("Elsa")
-                .HasAnnotation("ProductVersion", "8.0.12")
+                .HasAnnotation("ProductVersion", "9.0.17")
                 .HasAnnotation("Relational:MaxIdentifierLength", 63);
 
             NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
@@ -35,10 +35,12 @@ namespace Elsa.Persistence.EFCore.PostgreSql.Migrations.Labels
 
                     b.Property<string>("Name")
                         .IsRequired()
+                        .HasMaxLength(255)
                         .HasColumnType("text");
 
                     b.Property<string>("NormalizedName")
                         .IsRequired()
+                        .HasMaxLength(255)
                         .HasColumnType("text");
 
                     b.Property<string>("TenantId")
@@ -46,6 +48,10 @@ namespace Elsa.Persistence.EFCore.PostgreSql.Migrations.Labels
 
                     b.HasKey("Id");
 
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName");
+
                     b.ToTable("Labels", "Elsa");
                 });
 
diff --git a/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/20260913133317_PerTenantLabelUniqueness.Designer.cs b/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/20260913133317_PerTenantLabelUniqueness.Designer.cs
new file mode 100644
index 000000000..266d20c7f
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/20260913133317_PerTenantLabelUniqueness.Designer.cs
@@ -0,0 +1,101 @@
+// <auto-generated />
+using Elsa.Persistence.EFCore.Modules.Labels;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.SqlServer.Migrations.Labels
+{
+    [DbContext(typeof(LabelsElsaDbContext))]
+    [Migration("20260913133317_PerTenantLabelUniqueness")]
+    partial class PerTenantLabelUniqueness
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasDefaultSchema("Elsa")
+                .HasAnnotation("ProductVersion", "9.0.17")
+                .HasAnnotation("Relational:MaxIdentifierLength", 128);
+
+            SqlServerModelBuilderExtensions.UseIdentityColumns(modelBuilder);
+
+            modelBuilder.Entity("Elsa.Labels.Entities.Label", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("nvarchar(450)");
+
+                    b.Property<string>("Color")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("nvarchar(255)");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("nvarchar(255)");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("nvarchar(450)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName")
+                        .HasFilter("[TenantId] IS NOT NULL");
+
+                    b.ToTable("Labels", "Elsa");
+                });
+
+            modelBuilder.Entity("Elsa.Labels.Entities.WorkflowDefinitionLabel", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("nvarchar(450)");
+
+                    b.Property<string>("LabelId")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(450)");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("nvarchar(450)");
+
+                    b.Property<string>("WorkflowDefinitionId")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(450)");
+
+                    b.Property<string>("WorkflowDefinitionVersionId")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(450)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LabelId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_LabelId");
+
+                    b.HasIndex("TenantId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_TenantId");
+
+                    b.HasIndex("WorkflowDefinitionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionId");
+
+                    b.HasIndex("WorkflowDefinitionVersionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionVersionId");
+
+                    b.ToTable("WorkflowDefinitionLabels", "Elsa");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/20260913133317_PerTenantLabelUniqueness.cs b/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/20260913133317_PerTenantLabelUniqueness.cs
new file mode 100644
index 000000000..7af2747ea
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/20260913133317_PerTenantLabelUniqueness.cs
@@ -0,0 +1,157 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.SqlServer.Migrations.Labels
+{
+    /// <inheritdoc />
+    public partial class PerTenantLabelUniqueness : Migration
+    {
+        private readonly Elsa.Persistence.EFCore.IElsaDbContextSchema _schema;
+
+        /// <inheritdoc />
+        public PerTenantLabelUniqueness(Elsa.Persistence.EFCore.IElsaDbContextSchema schema)
+        {
+            _schema = schema;
+        }
+
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Default tenant is "" (not null). Stamp leftover nulls so the filtered unique
+            // index (TenantId IS NOT NULL) covers them. Duplicates are not deleted.
+            migrationBuilder.Sql($"""
+                UPDATE [{_schema.Schema}].[Labels]
+                SET [TenantId] = N''
+                WHERE [TenantId] IS NULL;
+                """);
+
+            // No silent dedupe. List leftover keys and abort; operators must resolve them before upgrading.
+            migrationBuilder.Sql($"""
+                IF EXISTS (
+                    SELECT 1
+                    FROM [{_schema.Schema}].[Labels]
+                    GROUP BY [TenantId], [NormalizedName]
+                    HAVING COUNT(*) > 1
+                )
+                BEGIN
+                    DECLARE @DuplicateKeys nvarchar(max);
+
+                    SELECT @DuplicateKeys = STRING_AGG(
+                        CAST(CONCAT(N'(', ISNULL([TenantId], N'<null>'), N', ', [NormalizedName], N')') AS nvarchar(max)),
+                        N'; '
+                    )
+                    FROM (
+                        SELECT [TenantId], [NormalizedName]
+                        FROM [{_schema.Schema}].[Labels]
+                        GROUP BY [TenantId], [NormalizedName]
+                        HAVING COUNT(*) > 1
+                    ) AS Duplicates;
+
+                    THROW 50001, CONCAT(
+                        N'Cannot create unique index IX_Label_TenantId_NormalizedName because leftover duplicate (TenantId, NormalizedName) rows exist. Operators must resolve leftover (TenantId, NormalizedName) rows before upgrade. Duplicate keys: ',
+                        LEFT(@DuplicateKeys, 1500)
+                    ), 1;
+                END
+                """);
+
+            // Name/NormalizedName are not truncated; list over-length Ids and abort before ALTER.
+            migrationBuilder.Sql($"""
+                IF EXISTS (
+                    SELECT 1
+                    FROM [{_schema.Schema}].[Labels]
+                    WHERE LEN([Name]) > 255 OR LEN([NormalizedName]) > 255
+                )
+                BEGIN
+                    DECLARE @OverLengthIds nvarchar(max);
+
+                    SELECT @OverLengthIds = STRING_AGG(CAST([Id] AS nvarchar(max)), N', ')
+                    FROM [{_schema.Schema}].[Labels]
+                    WHERE LEN([Name]) > 255 OR LEN([NormalizedName]) > 255;
+
+                    THROW 50002, CONCAT(
+                        N'Cannot alter Labels.Name / Labels.NormalizedName to nvarchar(255) because leftover rows exceed 255 characters. Operators must shorten or remove those rows before upgrade. Over-length Ids: ',
+                        LEFT(@OverLengthIds, 1500)
+                    ), 1;
+                END
+                """);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "TenantId",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "nvarchar(450)",
+                nullable: true,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)",
+                oldNullable: true);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Name",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "nvarchar(255)",
+                maxLength: 255,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "nvarchar(255)",
+                maxLength: 255,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                columns: new[] { "TenantId", "NormalizedName" },
+                unique: true,
+                filter: "[TenantId] IS NOT NULL");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "TenantId",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "nvarchar(max)",
+                nullable: true,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(450)",
+                oldNullable: true);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "nvarchar(max)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(255)",
+                oldMaxLength: 255);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Name",
+                schema: _schema.Schema,
+                table: "Labels",
+                type: "nvarchar(max)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(255)",
+                oldMaxLength: 255);
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs b/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
index f1fcd5bfa..510c43c54 100644
--- a/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
+++ b/src/modules/Elsa.Persistence.EFCore.SqlServer/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
@@ -17,7 +17,7 @@ namespace Elsa.Persistence.EFCore.SqlServer.Migrations.Labels
 #pragma warning disable 612, 618
             modelBuilder
                 .HasDefaultSchema("Elsa")
-                .HasAnnotation("ProductVersion", "8.0.12")
+                .HasAnnotation("ProductVersion", "9.0.17")
                 .HasAnnotation("Relational:MaxIdentifierLength", 128);
 
             SqlServerModelBuilderExtensions.UseIdentityColumns(modelBuilder);
@@ -35,17 +35,24 @@ namespace Elsa.Persistence.EFCore.SqlServer.Migrations.Labels
 
                     b.Property<string>("Name")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasMaxLength(255)
+                        .HasColumnType("nvarchar(255)");
 
                     b.Property<string>("NormalizedName")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasMaxLength(255)
+                        .HasColumnType("nvarchar(255)");
 
                     b.Property<string>("TenantId")
-                        .HasColumnType("nvarchar(max)");
+                        .HasColumnType("nvarchar(450)");
 
                     b.HasKey("Id");
 
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName")
+                        .HasFilter("[TenantId] IS NOT NULL");
+
                     b.ToTable("Labels", "Elsa");
                 });
 
diff --git a/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/20260913133258_PerTenantLabelUniqueness.Designer.cs b/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/20260913133258_PerTenantLabelUniqueness.Designer.cs
new file mode 100644
index 000000000..1de38d4f5
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/20260913133258_PerTenantLabelUniqueness.Designer.cs
@@ -0,0 +1,96 @@
+// <auto-generated />
+using Elsa.Persistence.EFCore.Modules.Labels;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.Sqlite.Migrations.Labels
+{
+    [DbContext(typeof(LabelsElsaDbContext))]
+    [Migration("20260913133258_PerTenantLabelUniqueness")]
+    partial class PerTenantLabelUniqueness
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasDefaultSchema("Elsa")
+                .HasAnnotation("ProductVersion", "9.0.17");
+
+            modelBuilder.Entity("Elsa.Labels.Entities.Label", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Color")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("NormalizedName")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName");
+
+                    b.ToTable("Labels", "Elsa");
+                });
+
+            modelBuilder.Entity("Elsa.Labels.Entities.WorkflowDefinitionLabel", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("LabelId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("TenantId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("WorkflowDefinitionId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("WorkflowDefinitionVersionId")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LabelId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_LabelId");
+
+                    b.HasIndex("TenantId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_TenantId");
+
+                    b.HasIndex("WorkflowDefinitionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionId");
+
+                    b.HasIndex("WorkflowDefinitionVersionId")
+                        .HasDatabaseName("WorkflowDefinitionLabel_WorkflowDefinitionVersionId");
+
+                    b.ToTable("WorkflowDefinitionLabels", "Elsa");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/20260913133258_PerTenantLabelUniqueness.cs b/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/20260913133258_PerTenantLabelUniqueness.cs
new file mode 100644
index 000000000..c95eb257a
--- /dev/null
+++ b/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/20260913133258_PerTenantLabelUniqueness.cs
@@ -0,0 +1,63 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Elsa.Persistence.EFCore.Sqlite.Migrations.Labels
+{
+    /// <inheritdoc />
+    public partial class PerTenantLabelUniqueness : Migration
+    {
+        private readonly Elsa.Persistence.EFCore.IElsaDbContextSchema _schema;
+
+        /// <inheritdoc />
+        public PerTenantLabelUniqueness(Elsa.Persistence.EFCore.IElsaDbContextSchema schema)
+        {
+            _schema = schema;
+        }
+
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Default tenant is "" (not null). Stamp leftover nulls so the unique index covers them.
+            migrationBuilder.Sql($"""
+                UPDATE "{_schema.Schema}"."Labels"
+                SET "TenantId" = ''
+                WHERE "TenantId" IS NULL;
+                """);
+
+            // No silent dedupe. List leftover keys and abort; operators must resolve them before upgrading.
+            migrationBuilder.Sql($"""
+                SELECT RAISE(ABORT, 'Cannot apply IX_Label_TenantId_NormalizedName. Operators must resolve leftover (TenantId, NormalizedName) rows before upgrade. Duplicate keys: ' ||
+                    (SELECT group_concat('(' || IFNULL("TenantId", '') || ', ' || "NormalizedName" || ')', ', ')
+                     FROM (
+                         SELECT "TenantId", "NormalizedName"
+                         FROM "{_schema.Schema}"."Labels"
+                         GROUP BY "TenantId", "NormalizedName"
+                         HAVING COUNT(*) > 1
+                     )))
+                WHERE EXISTS (
+                    SELECT 1
+                    FROM "{_schema.Schema}"."Labels"
+                    GROUP BY "TenantId", "NormalizedName"
+                    HAVING COUNT(*) > 1
+                );
+                """);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels",
+                columns: new[] { "TenantId", "NormalizedName" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Label_TenantId_NormalizedName",
+                schema: _schema.Schema,
+                table: "Labels");
+        }
+    }
+}
diff --git a/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs b/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
index fa1a007dd..5d431e181 100644
--- a/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
+++ b/src/modules/Elsa.Persistence.EFCore.Sqlite/Migrations/Labels/LabelsElsaDbContextModelSnapshot.cs
@@ -16,7 +16,7 @@ namespace Elsa.Persistence.EFCore.Sqlite.Migrations.Labels
 #pragma warning disable 612, 618
             modelBuilder
                 .HasDefaultSchema("Elsa")
-                .HasAnnotation("ProductVersion", "8.0.12");
+                .HasAnnotation("ProductVersion", "9.0.17");
 
             modelBuilder.Entity("Elsa.Labels.Entities.Label", b =>
                 {
@@ -31,10 +31,12 @@ namespace Elsa.Persistence.EFCore.Sqlite.Migrations.Labels
 
                     b.Property<string>("Name")
                         .IsRequired()
+                        .HasMaxLength(255)
                         .HasColumnType("TEXT");
 
                     b.Property<string>("NormalizedName")
                         .IsRequired()
+                        .HasMaxLength(255)
                         .HasColumnType("TEXT");
 
                     b.Property<string>("TenantId")
@@ -42,6 +44,10 @@ namespace Elsa.Persistence.EFCore.Sqlite.Migrations.Labels
 
                     b.HasKey("Id");
 
+                    b.HasIndex("TenantId", "NormalizedName")
+                        .IsUnique()
+                        .HasDatabaseName("IX_Label_TenantId_NormalizedName");
+
                     b.ToTable("Labels", "Elsa");
                 });
 
diff --git a/src/modules/Elsa.Persistence.EFCore/Modules/Labels/Configurations.cs b/src/modules/Elsa.Persistence.EFCore/Modules/Labels/Configurations.cs
index 91f47a026..216260d19 100644
--- a/src/modules/Elsa.Persistence.EFCore/Modules/Labels/Configurations.cs
+++ b/src/modules/Elsa.Persistence.EFCore/Modules/Labels/Configurations.cs
@@ -8,6 +8,16 @@ public class Configurations : IEntityTypeConfiguration<Label>, IEntityTypeConfig
 {
     public void Configure(EntityTypeBuilder<Label> builder)
     {
+        builder.Property(x => x.Name).HasMaxLength(Label.NameMaxLength).IsRequired();
+        builder.Property(x => x.NormalizedName).HasMaxLength(Label.NameMaxLength).IsRequired();
+
+        // Uniqueness is per tenant, matching Secrets (and User, Role, Application).
+        // A global unique index would make the name a shared resource across tenants.
+        // SQL Server/Oracle still emit a filtered unique index (TenantId IS NOT NULL).
+        // Default-tenant rows use "" — migrations stamp leftover null TenantId to "" first.
+        builder.HasIndex(x => new { x.TenantId, x.NormalizedName })
+            .HasDatabaseName($"IX_{nameof(Label)}_{nameof(Label.TenantId)}_{nameof(Label.NormalizedName)}")
+            .IsUnique();
     }
 
     public void Configure(EntityTypeBuilder<WorkflowDefinitionLabel> builder)
diff --git a/test/unit/Elsa.Labels.UnitTests/Entities/LabelNameMaxLengthTests.cs b/test/unit/Elsa.Labels.UnitTests/Entities/LabelNameMaxLengthTests.cs
new file mode 100644
index 000000000..b029f692f
--- /dev/null
+++ b/test/unit/Elsa.Labels.UnitTests/Entities/LabelNameMaxLengthTests.cs
@@ -0,0 +1,27 @@
+using Elsa.Labels.Entities;
+
+namespace Elsa.Labels.UnitTests.Entities;
+
+public class LabelNameMaxLengthTests
+{
+    [Fact]
+    public void Name_WhenLongerThanSharedMaximum_Throws()
+    {
+        var label = new Label { Id = "label-1" };
+
+        var exception = Assert.Throws<ArgumentException>(() => label.Name = new string('a', Label.NameMaxLength + 1));
+
+        Assert.Equal("Name", exception.ParamName);
+        Assert.Contains(Label.NameMaxLength.ToString(), exception.Message);
+    }
+
+    [Fact]
+    public void Name_WhenAtSharedMaximum_Succeeds()
+    {
+        var name = new string('a', Label.NameMaxLength);
+        var label = new Label { Id = "label-1", Name = name };
+
+        Assert.Equal(name, label.Name);
+        Assert.Equal(name, label.NormalizedName);
+    }
+}
diff --git a/test/unit/Elsa.Labels.UnitTests/Services/InMemoryLabelStoreUniquenessTests.cs b/test/unit/Elsa.Labels.UnitTests/Services/InMemoryLabelStoreUniquenessTests.cs
new file mode 100644
index 000000000..a3b6ce255
--- /dev/null
+++ b/test/unit/Elsa.Labels.UnitTests/Services/InMemoryLabelStoreUniquenessTests.cs
@@ -0,0 +1,180 @@
+using Elsa.Common.Multitenancy;
+using Elsa.Common.Services;
+using Elsa.Labels.Entities;
+using Elsa.Labels.Services;
+using Elsa.Testing.Shared.Multitenancy;
+
+namespace Elsa.Labels.UnitTests.Services;
+
+/// <summary>
+/// Memory must enforce the same per-tenant normalized-name uniqueness that EF Core
+/// enforces via <c>IX_Label_TenantId_NormalizedName</c> on <c>(TenantId, NormalizedName)</c>.
+/// </summary>
+public class InMemoryLabelStoreUniquenessTests
+{
+    [Fact(DisplayName = "SaveAsync rejects a different Id that repeats a normalized name in the same tenant")]
+    public async Task SaveAsync_WhenNormalizedNameExistsUnderAnotherId_Throws()
+    {
+        var store = CreateStore("tenant-a");
+        await store.SaveAsync(Label("label-1", "Urgent", "tenant-a"));
+
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            store.SaveAsync(Label("label-2", "urgent", "tenant-a")));
+
+        Assert.Contains("already exists", exception.Message);
+        var stored = (await store.ListAsync()).Items.ToList();
+        Assert.Equal("label-1", Assert.Single(stored).Id);
+    }
+
+    [Fact(DisplayName = "SaveAsync allows the same Id to update its own name")]
+    public async Task SaveAsync_WhenSameIdUpdatesName_Succeeds()
+    {
+        var store = CreateStore("tenant-a");
+        await store.SaveAsync(Label("label-1", "Urgent", "tenant-a"));
+
+        await store.SaveAsync(Label("label-1", "Critical", "tenant-a"));
+
+        var stored = await store.FindByIdAsync("label-1");
+        Assert.Equal("Critical", stored!.Name);
+        Assert.Equal("critical", stored.NormalizedName);
+    }
+
+    [Fact(DisplayName = "SaveAsync allows the same normalized name in different tenants")]
+    public async Task SaveAsync_WhenNormalizedNameRepeatsInAnotherTenant_Succeeds()
+    {
+        var labels = new MemoryStore<Label>();
+        var associations = new MemoryStore<WorkflowDefinitionLabel>();
+        var tenantA = new InMemoryLabelStore(labels, associations, new TestTenantAccessor("tenant-a"));
+        var tenantB = new InMemoryLabelStore(labels, associations, new TestTenantAccessor("tenant-b"));
+
+        await tenantA.SaveAsync(Label("label-a", "Urgent", "tenant-a"));
+        await tenantB.SaveAsync(Label("label-b", "Urgent", "tenant-b"));
+
+        Assert.Equal("urgent", (await tenantA.FindByIdAsync("label-a"))!.NormalizedName);
+        Assert.Equal("urgent", (await tenantB.FindByIdAsync("label-b"))!.NormalizedName);
+    }
+
+    [Fact(DisplayName = "SaveAsync rejects renaming onto a normalized name another Id already owns")]
+    public async Task SaveAsync_WhenRenamingOntoAnotherIdsNormalizedName_Throws()
+    {
+        var store = CreateStore("tenant-a");
+        await store.SaveAsync(Label("label-1", "Urgent", "tenant-a"));
+        await store.SaveAsync(Label("label-2", "Later", "tenant-a"));
+
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            store.SaveAsync(Label("label-2", "Urgent", "tenant-a")));
+
+        Assert.Contains("already exists", exception.Message);
+        Assert.Equal("Later", (await store.FindByIdAsync("label-2"))!.Name);
+    }
+
+    [Fact(DisplayName = "SaveAsync leaves the stored name unchanged when a Find result is renamed onto a collision")]
+    public async Task SaveAsync_WhenFoundLabelRenamedOntoCollision_LeavesStoredNameUnchanged()
+    {
+        var store = CreateStore("tenant-a");
+        await store.SaveAsync(Label("label-1", "Urgent", "tenant-a"));
+        await store.SaveAsync(Label("label-2", "Later", "tenant-a"));
+
+        var found = await store.FindByIdAsync("label-2");
+        found!.Name = "Urgent";
+
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() => store.SaveAsync(found));
+
+        Assert.Contains("already exists", exception.Message);
+        var stored = await store.FindByIdAsync("label-2");
+        Assert.Equal("Later", stored!.Name);
+        Assert.Equal("later", stored.NormalizedName);
+    }
+
+    [Fact(DisplayName = "SaveAsync treats a stamped ambient tenant as the uniqueness tenant")]
+    public async Task SaveAsync_WhenTenantIdUnset_UsesStampedAmbientTenantForUniqueness()
+    {
+        var store = CreateStore("tenant-a");
+        await store.SaveAsync(Label("label-1", "Urgent", tenantId: null));
+
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            store.SaveAsync(Label("label-2", "Urgent", tenantId: null)));
+
+        Assert.Contains("already exists", exception.Message);
+        Assert.Equal("tenant-a", (await store.FindByIdAsync("label-1"))!.TenantId);
+    }
+
+    [Fact(DisplayName = "SaveAsync allows the same normalized name for * and a tenant-scoped label")]
+    public async Task SaveAsync_WhenAgnosticAndTenantScopedShareNormalizedName_Succeeds()
+    {
+        var store = CreateStore("tenant-a");
+
+        await store.SaveAsync(Label("label-star", "Urgent", Tenant.AgnosticTenantId));
+        await store.SaveAsync(Label("label-a", "Urgent", "tenant-a"));
+
+        Assert.NotNull(await store.FindByIdAsync("label-star"));
+        Assert.NotNull(await store.FindByIdAsync("label-a"));
+    }
+
+    [Fact(DisplayName = "SaveAsync keeps NormalizedName in sync with Name")]
+    public async Task SaveAsync_WhenNormalizedNameIsStale_ResyncsFromName()
+    {
+        var store = CreateStore("tenant-a");
+        var label = Label("label-1", "Urgent", "tenant-a");
+        label.NormalizedName = "stale";
+
+        await store.SaveAsync(label);
+
+        Assert.Equal("urgent", (await store.FindByIdAsync("label-1"))!.NormalizedName);
+    }
+
+    [Fact(DisplayName = "SaveManyAsync rejects a batch that repeats a normalized name already in the store")]
+    public async Task SaveManyAsync_WhenNormalizedNameExistsUnderAnotherId_Throws()
+    {
+        var store = CreateStore("tenant-a");
+        await store.SaveAsync(Label("label-1", "Urgent", "tenant-a"));
+
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            store.SaveManyAsync([Label("label-2", "Urgent", "tenant-a")]));
+
+        Assert.Contains("already exists", exception.Message);
+        Assert.Null(await store.FindByIdAsync("label-2"));
+    }
+
+    [Fact(DisplayName = "SaveManyAsync rejects two different Ids that share a normalized name")]
+    public async Task SaveManyAsync_WhenBatchRepeatsNormalizedName_Throws()
+    {
+        var store = CreateStore("tenant-a");
+
+        var exception = await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            store.SaveManyAsync([
+                Label("label-1", "Urgent", "tenant-a"),
+                Label("label-2", "urgent", "tenant-a")
+            ]));
+
+        Assert.Contains("already exists", exception.Message);
+        Assert.Empty((await store.ListAsync()).Items);
+    }
+
+    [Fact(DisplayName = "SaveManyAsync allows swapping normalized names within one batch")]
+    public async Task SaveManyAsync_WhenBatchSwapsNormalizedNames_Succeeds()
+    {
+        var store = CreateStore("tenant-a");
+        await store.SaveAsync(Label("label-1", "Urgent", "tenant-a"));
+        await store.SaveAsync(Label("label-2", "Later", "tenant-a"));
+
+        await store.SaveManyAsync([
+            Label("label-1", "Later", "tenant-a"),
+            Label("label-2", "Urgent", "tenant-a")
+        ]);
+
+        Assert.Equal("later", (await store.FindByIdAsync("label-1"))!.NormalizedName);
+        Assert.Equal("urgent", (await store.FindByIdAsync("label-2"))!.NormalizedName);
+    }
+
+    private static InMemoryLabelStore CreateStore(string tenantId) =>
+        new(new MemoryStore<Label>(), new MemoryStore<WorkflowDefinitionLabel>(), new TestTenantAccessor(tenantId));
+
+    private static Label Label(string id, string name, string? tenantId) =>
+        new()
+        {
+            Id = id,
+            Name = name,
+            TenantId = tenantId
+        };
+}
diff --git a/test/unit/Elsa.Persistence.EFCore.UnitTests/LabelNormalizedNameUniquenessTests.cs b/test/unit/Elsa.Persistence.EFCore.UnitTests/LabelNormalizedNameUniquenessTests.cs
new file mode 100644
index 000000000..45c2030d0
--- /dev/null
+++ b/test/unit/Elsa.Persistence.EFCore.UnitTests/LabelNormalizedNameUniquenessTests.cs
@@ -0,0 +1,40 @@
+using Elsa.Labels.Entities;
+using Elsa.Persistence.EFCore.Modules.Labels;
+using Microsoft.EntityFrameworkCore;
+
+namespace Elsa.Persistence.EFCore.UnitTests;
+
+/// <summary>
+/// The Labels unique index must be per tenant, matching Secrets'
+/// <c>IX_Secret_TenantId_NormalizedName</c>. A global unique index would make
+/// the name a shared resource: the second tenant could not create "urgent".
+/// </summary>
+public class LabelNormalizedNameUniquenessTests
+{
+    [Fact]
+    public void Label_HasUniqueIndex_OnTenantIdAndNormalizedName()
+    {
+        var builder = new ModelBuilder();
+        new Configurations().Configure(builder.Entity<Label>());
+
+        var index = builder.Model
+            .FindEntityType(typeof(Label))!
+            .GetIndexes()
+            .Single(x => x.IsUnique);
+
+        Assert.Equal(["TenantId", "NormalizedName"], index.Properties.Select(x => x.Name));
+        Assert.Equal("IX_Label_TenantId_NormalizedName", index.GetDatabaseName());
+    }
+
+    [Fact]
+    public void Label_NameAndNormalizedName_HaveSharedMaxLength()
+    {
+        var builder = new ModelBuilder();
+        new Configurations().Configure(builder.Entity<Label>());
+        var entity = builder.Model.FindEntityType(typeof(Label))!;
+
+        Assert.Equal(Label.NameMaxLength, entity.FindProperty(nameof(Label.Name))!.GetMaxLength());
+        Assert.Equal(Label.NameMaxLength, entity.FindProperty(nameof(Label.NormalizedName))!.GetMaxLength());
+        Assert.Equal(255, Label.NameMaxLength);
+    }
+}
diff --git a/test/unit/Elsa.Persistence.EFCore.UnitTests/LabelPerTenantUniquenessMigrationTests.cs b/test/unit/Elsa.Persistence.EFCore.UnitTests/LabelPerTenantUniquenessMigrationTests.cs
new file mode 100644
index 000000000..5852a4de0
--- /dev/null
+++ b/test/unit/Elsa.Persistence.EFCore.UnitTests/LabelPerTenantUniquenessMigrationTests.cs
@@ -0,0 +1,101 @@
+namespace Elsa.Persistence.EFCore.UnitTests;
+
+/// <summary>
+/// PerTenantLabelUniqueness must stamp null TenantId to "" and must not
+/// auto-delete duplicate labels (associations would be at risk). A preflight
+/// lists leftover keys and aborts; CreateIndex then fails loudly if any remain.
+/// SQL Server/MySQL/Oracle also preflight over-length Name/NormalizedName
+/// before narrowing those columns. PostgreSQL/SQLite keep provider column types.
+/// </summary>
+public class LabelPerTenantUniquenessMigrationTests
+{
+    [Theory]
+    [InlineData("Elsa.Persistence.EFCore.Sqlite")]
+    [InlineData("Elsa.Persistence.EFCore.SqlServer")]
+    [InlineData("Elsa.Persistence.EFCore.PostgreSql")]
+    [InlineData("Elsa.Persistence.EFCore.MySql")]
+    [InlineData("Elsa.Persistence.EFCore.Oracle")]
+    public void PerTenantLabelUniqueness_StampsNullTenantIdAndDoesNotDeleteDuplicates(string providerProject)
+    {
+        var migration = FindMigration(providerProject);
+
+        Assert.Contains("TenantId", migration, StringComparison.Ordinal);
+        Assert.Contains("IS NULL", migration, StringComparison.Ordinal);
+        Assert.DoesNotContain("DELETE FROM", migration, StringComparison.OrdinalIgnoreCase);
+        Assert.DoesNotContain("DeleteData", migration, StringComparison.OrdinalIgnoreCase);
+        Assert.DoesNotContain("COALESCE", migration, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Theory]
+    [InlineData("Elsa.Persistence.EFCore.Sqlite", "RAISE")]
+    [InlineData("Elsa.Persistence.EFCore.SqlServer", "THROW")]
+    [InlineData("Elsa.Persistence.EFCore.PostgreSql", "RAISE EXCEPTION")]
+    [InlineData("Elsa.Persistence.EFCore.MySql", "SIGNAL")]
+    [InlineData("Elsa.Persistence.EFCore.Oracle", "RAISE_APPLICATION_ERROR")]
+    public void PerTenantLabelUniqueness_PreflightsDuplicateKeys(string providerProject, string abortKeyword)
+    {
+        var migration = FindMigration(providerProject);
+
+        Assert.Contains(abortKeyword, migration, StringComparison.Ordinal);
+        Assert.Contains("COUNT(*)", migration, StringComparison.Ordinal);
+        Assert.Contains("Duplicate keys", migration, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("HAVING COUNT(*) > 1", migration, StringComparison.Ordinal);
+    }
+
+    [Theory]
+    [InlineData("Elsa.Persistence.EFCore.SqlServer")]
+    [InlineData("Elsa.Persistence.EFCore.MySql")]
+    [InlineData("Elsa.Persistence.EFCore.Oracle")]
+    public void PerTenantLabelUniqueness_PreflightsOverLengthRowsBeforeAlter(string providerProject)
+    {
+        var migration = FindMigration(providerProject);
+
+        Assert.Contains("255", migration, StringComparison.Ordinal);
+        Assert.Contains("Over-length", migration, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("AlterColumn", migration, StringComparison.Ordinal);
+    }
+
+    [Theory]
+    [InlineData("Elsa.Persistence.EFCore.Sqlite")]
+    [InlineData("Elsa.Persistence.EFCore.PostgreSql")]
+    public void PerTenantLabelUniqueness_KeepsUnboundedProviderColumnTypes(string providerProject)
+    {
+        var migration = FindMigration(providerProject);
+
+        Assert.DoesNotContain("AlterColumn", migration, StringComparison.Ordinal);
+        Assert.DoesNotContain("varchar(255)", migration, StringComparison.OrdinalIgnoreCase);
+        Assert.DoesNotContain("nvarchar(255)", migration, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Theory]
+    [InlineData("Elsa.Persistence.EFCore.SqlServer", "[TenantId] IS NOT NULL")]
+    [InlineData("Elsa.Persistence.EFCore.Oracle", "\\\"TenantId\\\" IS NOT NULL")]
+    public void PerTenantLabelUniqueness_KeepsFilteredUniqueIndex(string providerProject, string filter)
+    {
+        var migration = FindMigration(providerProject);
+        Assert.Contains(filter, migration, StringComparison.Ordinal);
+    }
+
+    private static string FindMigration(string providerProject)
+    {
+        var repoRoot = FindRepoRoot();
+        var labelsDir = Path.Combine(repoRoot, "src", "modules", providerProject, "Migrations", "Labels");
+        var path = Directory.GetFiles(labelsDir, "*PerTenantLabelUniqueness.cs")
+            .Single(file => !file.EndsWith(".Designer.cs", StringComparison.Ordinal));
+        return File.ReadAllText(path);
+    }
+
+    private static string FindRepoRoot()
+    {
+        var directory = new DirectoryInfo(AppContext.BaseDirectory);
+        while (directory is not null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "Elsa.sln")))
+                return directory.FullName;
+
+            directory = directory.Parent;
+        }
+
+        throw new InvalidOperationException("Could not find Elsa.sln from the test output directory.");
+    }
+}