[release-notes] .NET Libraries in .NET 11 GA

release-notes/11.0/11.0.0/libraries.md

@@ -1,3 +1,69 @@
 # Libraries in .NET 11 - Release Notes
 
-<!-- TODO: Add release notes or confirm there are no noteworthy changes. -->
+The final library updates for .NET 11 include experimental public-key encryption, JSON Lines serialization fixes, and migration guidance for tensor and compression APIs.
+
+- [Experimental public-key encryption](#experimental-public-key-encryption)
+- [JSON Lines streaming](#json-lines-streaming)
+- [Breaking changes from .NET 10](#breaking-changes-from-net-10)
+- [Changes for users of earlier release candidates](#changes-for-users-of-earlier-release-candidates)
+
+## Library improvements
+
+### Experimental public-key encryption
+
+A managed implementation of Hybrid Public Key Encryption (HPKE) lets protocols encrypt data for a recipient using the recipient's public key, rather than requiring a previously shared secret. Check `Hpke.IsSupported` for the algorithm suite you intend to use; availability varies by platform and suite ([dotnet/runtime#134442](https://github.com/dotnet/runtime/pull/134442)).
+
+The following example generates a recipient's key, encrypts using only its public key, and decrypts with the recipient's private key:
+
+```csharp
+using System.Security.Cryptography;
+using System.Text;
+
+var suite = new HpkeSuite(
+    HpkeKem.DHKEM_P256_HKDF_SHA256,
+    HpkeKdf.HKDF_SHA256,
+    HpkeAead.AES_128_GCM);
+
+if (!Hpke.IsSupported(suite))
+    throw new PlatformNotSupportedException("The selected HPKE suite is unavailable.");
+
+using var recipient = Hpke.GenerateKey(suite);
+using var sender = Hpke.ImportEncapsulationKey(suite, recipient.ExportEncapsulationKey());
+sender.Seal("Hello"u8, out byte[] encapsulatedSecret, out byte[] ciphertext);
+byte[] plaintext = recipient.Open(encapsulatedSecret, ciphertext);
+Console.WriteLine(Encoding.UTF8.GetString(plaintext)); // Hello
+```
+
+These APIs are experimental and produce diagnostic `SYSLIB5009`. To run the example while keeping that diagnostic visible, configure it as a warning in your project's `.editorconfig`:
+
+```editorconfig
+[*.cs]
+dotnet_diagnostic.SYSLIB5009.severity = warning
+```
+
+### JSON Lines streaming
+
+`JsonSerializer.SerializeAsyncEnumerable` now streams each JSONL entry instead of buffering the entire entry. This also fixes serialization of entries that contain nested asynchronous enumerables ([dotnet/runtime#134593](https://github.com/dotnet/runtime/pull/134593)).
+
+For features introduced throughout the release, see [What's new in the .NET 11 libraries](https://learn.microsoft.com/dotnet/core/whats-new/dotnet-11/libraries).
+
+## Breaking changes from .NET 10
+
+Updating the `System.Numerics.Tensors` package changes shape alignment and rejects unsupported overlapping storage layouts. These changes also apply to the package's supported older target frameworks. Review code that depends on a particular shape or overlapping copy being accepted, and follow the guidance on [tensor shape alignment](https://learn.microsoft.com/dotnet/core/compatibility/core-libraries/11/tensor-shape-alignment) and [tensor storage-layout validation](https://learn.microsoft.com/dotnet/core/compatibility/core-libraries/11/tensor-storage-layout-validation) ([dotnet/runtime#135281](https://github.com/dotnet/runtime/pull/135281)).
+
+Unsupported overlapping copies now throw before writing output. Use separate destination storage or snapshot the source when overlap is unsupported.
+
+See [Breaking changes in .NET 11](https://learn.microsoft.com/dotnet/core/compatibility/11) for the full compatibility guidance.
+
+## Changes for users of earlier release candidates
+
+`ZstandardDictionary.Train` now returns raw dictionary bytes (`byte[]`) instead of a prepared `ZstandardDictionary`. Prepare those bytes with `ZstandardDictionary.Create` so the requested compression quality is used ([dotnet/runtime#135756](https://github.com/dotnet/runtime/pull/135756)).
+
+Given concatenated training samples in `samples` and their individual lengths in `sampleLengths`:
+
+```csharp
+byte[] data = ZstandardDictionary.Train(samples, sampleLengths, maxDictionarySize: 4096);
+using ZstandardDictionary dictionary = ZstandardDictionary.Create(data, quality: 19);
+```
+
+<!-- API signatures and replacement usage verified against the supplied local .NET 11.0.0 build with SDK 11.0.100. Correlation with the final public GA artifact is pending. -->