fix Azure object ETag consistency across reads

Author: KSemenenko

Directory.Build.props

@@ -29,8 +29,8 @@
         <RepositoryUrl>https://github.com/managedcode/Storage</RepositoryUrl>
         <PackageProjectUrl>https://github.com/managedcode/Storage</PackageProjectUrl>
         <Product>Managed Code - Storage</Product>
-        <Version>10.0.16</Version>
-        <PackageVersion>10.0.16</PackageVersion>
+        <Version>10.0.17</Version>
+        <PackageVersion>10.0.17</PackageVersion>
 
     </PropertyGroup>
 

README.md

@@ -106,7 +106,7 @@ Cloud storage vendors expose distinct SDKs, option models, and authentication pa
 - ASP.NET storage controllers, chunk orchestration services, and a SignalR hub/client pair that deliver resumable uploads, ranged downloads, CRC32 validation, and real-time progress.
 - `ManagedCode.Storage.Client` brings streaming uploads/downloads, CRC32 helpers, and MIME discovery via `MimeHelper` to any .NET app.
 - Strongly typed option objects (`UploadOptions`, `DownloadOptions`, `DeleteOptions`, `MetadataOptions`, `LegalHoldOptions`, etc.) let you configure directories, metadata, and legal holds in one place.
-- Azure object listings return bounded pages with opaque continuation tokens and `null` after the last page, including empty listings.
+- Azure object listings return bounded pages with opaque continuation tokens and `null` after the last page, including empty listings. Listing and properties reads expose the same opaque ETag for the same revision.
 - Azure metadata preserves Unicode filenames and other logical string values through a provider-owned ASCII transport envelope; ordinary native ASCII metadata remains interoperable. See [metadata transport](https://github.com/managed-code-hub/Storage/blob/main/docs/Features/provider-azure-blob.md#metadata-transport).
 - Virtual File System package provides a file/directory API (`IVirtualFileSystem`) on top of the configured `IStorage` and can cache metadata for faster repeated operations, including browser storage verified through real Playwright flows in both Blazor WebAssembly and Interactive Server hosts.
 - For decisions requiring current storage state, `IVirtualFileSystem.StorageFileExistsAsync` bypasses that cache and propagates provider errors. `WriteBytesIfAbsentOrSameAsync` uses an atomic provider capability and accepts only an exact immutable retry. `ManagedCode.Storage.Core.Primitives.VerifiedContentSnapshot` verifies bounded reads by length and SHA-256.

Storages/ManagedCode.Storage.Azure/AzureObjectOperations.cs

@@ -19,7 +19,7 @@ internal sealed class AzureObjectOperations(BlobContainerClient container) : IMu
     public Task<StorageContainerInfo> GetContainerInfoAsync(CancellationToken cancellationToken = default) => ExecuteAsync(async () =>
     {
         var value = (await container.GetPropertiesAsync(cancellationToken: cancellationToken)).Value;
-        return new StorageContainerInfo(value.ETag.ToString(), value.PublicAccess == PublicAccessType.None,
+        return new StorageContainerInfo(value.ETag.ToString("H"), value.PublicAccess == PublicAccessType.None,
             AzureMetadataTransport.Decode(value.Metadata));
     });
 
@@ -50,7 +50,7 @@ public Task<Stream> OpenObjectReadAsync(string path, StorageReadOptions? options
         ArgumentOutOfRangeException.ThrowIfNegative(options.Offset);
         if (options.Length is <= 0) throw new ArgumentOutOfRangeException(nameof(options));
         var blob = container.GetBlobClient(path);
-        var etag = options.IfMatch ?? (await blob.GetPropertiesAsync(cancellationToken: cancellationToken)).Value.ETag.ToString();
+        var etag = options.IfMatch ?? (await blob.GetPropertiesAsync(cancellationToken: cancellationToken)).Value.ETag.ToString("H");
         if (options.Length is null)
         {
             return await blob.OpenReadAsync(new BlobOpenReadOptions(false)
@@ -98,7 +98,7 @@ public Task<StorageObjectPage> ListObjectsAsync(string? prefix = null, string? c
                            .AsPages(continuationToken, pageSize))
         {
             return new StorageObjectPage(page.Values.Select(item => new StorageObjectInfo(item.Name,
-                item.Properties.ETag?.ToString() ?? throw new InvalidDataException("Object listing returned no ETag."),
+                item.Properties.ETag?.ToString("H") ?? throw new InvalidDataException("Object listing returned no ETag."),
                 item.Properties.ContentLength ?? throw new InvalidDataException("Object listing returned no length."),
                 item.Properties.ContentType, item.Properties.ContentEncoding, AzureMetadataTransport.Decode(item.Metadata), item.Properties.LastModified)).ToArray(), string.IsNullOrEmpty(page.ContinuationToken) ? null : page.ContinuationToken);
         }
@@ -126,7 +126,7 @@ public Task<StorageObjectInfo> CommitPartsAsync(string path, IReadOnlyList<strin
     private async Task<StorageObjectInfo> ReadWrittenInfoAsync(string path, ETag etag, CancellationToken cancellationToken) =>
         Info(path, (await container.GetBlobClient(path).GetPropertiesAsync(new BlobRequestConditions { IfMatch = etag }, cancellationToken)).Value);
 
-    private static StorageObjectInfo Info(string path, BlobProperties value) => new(path, value.ETag.ToString(), value.ContentLength,
+    private static StorageObjectInfo Info(string path, BlobProperties value) => new(path, value.ETag.ToString("H"), value.ContentLength,
         value.ContentType, value.ContentEncoding, AzureMetadataTransport.Decode(value.Metadata), value.LastModified);
 
     private static BlobRequestConditions Conditions(StorageWriteOptions options)

Tests/ManagedCode.Storage.Tests/Storages/Azure/AzureObjectStorageTests.cs

@@ -227,6 +227,7 @@ public async Task MetadataPaginationAndDeletion_PreserveContainerBoundary()
         (await objects.ListObjectsAsync("files/", pageSize: 1000)).ContinuationToken.ShouldBeNull();
         (await objects.ListObjectsAsync("absent/")).ContinuationToken.ShouldBeNull();
         var info = next.Items[0];
+        (await objects.GetObjectInfoAsync(info.Path)).ETag.ShouldBe(info.ETag);
         await objects.SetObjectMetadataAsync(info.Path, new Dictionary<string, string> { ["hash"] = "value" }, info.ETag);
         (await objects.GetObjectInfoAsync(info.Path)).Metadata["hash"].ShouldBe("value");
         (await Should.ThrowAsync<StorageOperationException>(() => objects.SetObjectMetadataAsync(info.Path, new Dictionary<string, string>(), info.ETag))).IsConflict.ShouldBeTrue();

docs/Architecture.md

@@ -32,6 +32,8 @@ flowchart LR
 
 For immutable uploads, `WriteIfAbsentOrSameAsync` streams an expected-length request through SHA-256, retries a conflicting write by reading the current ETag-pinned object, and accepts only byte-identical content with matching content type, encoding, and metadata. It returns the stored ETag, digest, and whether the object was reused; a mismatch keeps the provider conflict. Neither input nor stored content is buffered as a whole.
 
+Azure object ETags use the SDK header format across listing and properties reads, so the same revision has the same opaque token and can be compared before a conditional operation.
+
 Object conditions (`IfAbsent`, `IfMatch`) are enforced by the service for writes,
 metadata updates and reads. Read ranges use a fixed ETag and stream data without
 loading the object into memory. Multipart part IDs are opaque base64 identifiers

docs/Features/provider-azure-blob.md

@@ -50,6 +50,7 @@ builder.Services.AddAzureStorageAsDefault(options =>
 
 - Supports container creation when `CreateContainerIfNotExists = true`.
 - `IObjectStorage.ListObjectsAsync` returns one bounded page and preserves opaque nonempty continuation tokens. The final page returns `null`, including empty listings; Azure's empty terminal marker never becomes another continuation request.
+- Returned object/container ETags use the SDK header format, including quotes, across listing and properties reads. An unchanged object retains the same revision token; stale conditional mutations remain rejected.
 - Uses Azure SDK transfer options when configured (`UploadTransferOptions`).
 - Builds the upload result from the successful Azure upload response and the caller's options, without issuing a second blob-properties request that can race with deletion or lifecycle processing.
 - Returns a failed metadata result for an absent blob without logging the expected Azure `404 BlobNotFound` response as an unhandled exception; other metadata failures retain error logging.