refactor(core): add IContentVersionOperationService interface

Part of ContentService refactoring Phase 3.
Defines version operations to be extracted from ContentService.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/Umbraco.Core/Services/IContentVersionOperationService.cs

@@ -0,0 +1,133 @@
+// src/Umbraco.Core/Services/IContentVersionOperationService.cs
+using Umbraco.Cms.Core.Models;
+
+namespace Umbraco.Cms.Core.Services;
+
+/// <summary>
+/// Service for content version operations (retrieving versions, rollback, deleting versions).
+/// </summary>
+/// <remarks>
+/// <para>
+/// <strong>Implementation Note:</strong> Do not implement this interface directly.
+/// Instead, inherit from <see cref="ContentServiceBase"/> which provides required
+/// infrastructure (scoping, repository access, auditing). Direct implementation
+/// without this base class will result in missing functionality.
+/// </para>
+/// <para>
+/// This interface is part of the ContentService refactoring initiative (Phase 3).
+/// It extracts version operations into a focused, testable service.
+/// </para>
+/// <para>
+/// <strong>Note:</strong> This interface provides synchronous version operations
+/// extracted from <see cref="IContentService"/>. For async API-layer version operations,
+/// see <see cref="IContentVersionService"/> which orchestrates via this service.
+/// </para>
+/// <para>
+/// <strong>Versioning Policy:</strong> This interface follows additive-only changes.
+/// New methods may be added with default implementations. Existing methods will not
+/// be removed or have signatures changed without a 2 major version deprecation period.
+/// </para>
+/// <para>
+/// <strong>Version History:</strong>
+/// <list type="bullet">
+///   <item><description>v1.0 (Phase 3): Initial interface with GetVersion, GetVersions, Rollback, DeleteVersions operations</description></item>
+/// </list>
+/// </para>
+/// </remarks>
+/// <since>1.0</since>
+public interface IContentVersionOperationService : IService
+{
+    #region Version Retrieval
+
+    /// <summary>
+    /// Gets a specific version of content by version id.
+    /// </summary>
+    /// <param name="versionId">The version id to retrieve.</param>
+    /// <returns>The content version, or null if not found.</returns>
+    IContent? GetVersion(int versionId);
+
+    /// <summary>
+    /// Gets all versions of a content item.
+    /// </summary>
+    /// <param name="id">The content id.</param>
+    /// <returns>All versions of the content, ordered by version date descending.</returns>
+    IEnumerable<IContent> GetVersions(int id);
+
+    /// <summary>
+    /// Gets a paged subset of versions for a content item.
+    /// </summary>
+    /// <param name="id">The content id.</param>
+    /// <param name="skip">Number of versions to skip.</param>
+    /// <param name="take">Number of versions to take.</param>
+    /// <returns>Paged versions of the content, ordered by version date descending.</returns>
+    IEnumerable<IContent> GetVersionsSlim(int id, int skip, int take);
+
+    /// <summary>
+    /// Gets version ids for a content item, ordered with latest first.
+    /// </summary>
+    /// <param name="id">The content id.</param>
+    /// <param name="maxRows">Maximum number of version ids to return. Must be positive.</param>
+    /// <returns>Version ids ordered with latest first. Empty if content not found.</returns>
+    /// <exception cref="ArgumentOutOfRangeException">Thrown if maxRows is less than or equal to zero.</exception>
+    /// <remarks>
+    /// This method acquires a read lock on the content tree for consistency with other
+    /// version retrieval methods. If content with the specified id does not exist,
+    /// an empty enumerable is returned rather than throwing an exception.
+    /// </remarks>
+    IEnumerable<int> GetVersionIds(int id, int maxRows);
+
+    #endregion
+
+    #region Rollback
+
+    /// <summary>
+    /// Rolls back content to a previous version.
+    /// </summary>
+    /// <param name="id">The content id to rollback.</param>
+    /// <param name="versionId">The version id to rollback to.</param>
+    /// <param name="culture">The culture to rollback, or "*" for all cultures.</param>
+    /// <param name="userId">The user performing the rollback.</param>
+    /// <returns>The operation result indicating success or failure.</returns>
+    /// <remarks>
+    /// Fires <see cref="Notifications.ContentRollingBackNotification"/> (cancellable) before rollback
+    /// and <see cref="Notifications.ContentRolledBackNotification"/> after successful rollback.
+    /// The rollback copies property values from the target version to the current content
+    /// and saves it, creating a new version.
+    /// </remarks>
+    OperationResult Rollback(int id, int versionId, string culture = "*", int userId = Constants.Security.SuperUserId);
+
+    #endregion
+
+    #region Version Deletion
+
+    /// <summary>
+    /// Permanently deletes versions of content prior to a specific date.
+    /// </summary>
+    /// <param name="id">The content id.</param>
+    /// <param name="versionDate">Delete versions older than this date.</param>
+    /// <param name="userId">The user performing the deletion.</param>
+    /// <remarks>
+    /// This method will never delete the latest version of a content item.
+    /// Fires <see cref="Notifications.ContentDeletingVersionsNotification"/> (cancellable) before deletion
+    /// and <see cref="Notifications.ContentDeletedVersionsNotification"/> after deletion.
+    /// </remarks>
+    void DeleteVersions(int id, DateTime versionDate, int userId = Constants.Security.SuperUserId);
+
+    /// <summary>
+    /// Permanently deletes a specific version of content.
+    /// </summary>
+    /// <param name="id">The content id.</param>
+    /// <param name="versionId">The version id to delete.</param>
+    /// <param name="deletePriorVersions">If true, also deletes all versions prior to the specified version.</param>
+    /// <param name="userId">The user performing the deletion.</param>
+    /// <remarks>
+    /// This method will never delete the current version or published version of a content item.
+    /// Fires <see cref="Notifications.ContentDeletingVersionsNotification"/> (cancellable) before deletion
+    /// and <see cref="Notifications.ContentDeletedVersionsNotification"/> after deletion.
+    /// If deletePriorVersions is true, it first deletes all versions prior to the specified version's date,
+    /// then deletes the specified version.
+    /// </remarks>
+    void DeleteVersion(int id, int versionId, bool deletePriorVersions, int userId = Constants.Security.SuperUserId);
+
+    #endregion
+}