From 19d6107cb0b15cefc14cbe1fdedb0c752535ed7d Mon Sep 17 00:00:00 2001
From: David Badura <david.badura@patchlevel.de>
Date: Sat, 28 Feb 2026 10:25:35 +0100
Subject: [PATCH] mark stack hydrator experimental

---
 src/CoreExtension.php                                            | 1 +
 src/Extension.php                                                | 1 +
 src/Extension/Cryptography/Attribute/DataSubjectId.php           | 1 +
 src/Extension/Cryptography/Attribute/SensitiveData.php           | 1 +
 src/Extension/Cryptography/BaseCryptographer.php                 | 1 +
 src/Extension/Cryptography/Cipher/Cipher.php                     | 1 +
 src/Extension/Cryptography/Cipher/CipherKey.php                  | 1 +
 src/Extension/Cryptography/Cipher/CipherKeyFactory.php           | 1 +
 src/Extension/Cryptography/Cipher/CreateCipherKeyFailed.php      | 1 +
 src/Extension/Cryptography/Cipher/DecryptionFailed.php           | 1 +
 src/Extension/Cryptography/Cipher/EncryptionFailed.php           | 1 +
 src/Extension/Cryptography/Cipher/MethodNotSupported.php         | 1 +
 src/Extension/Cryptography/Cipher/OpensslCipher.php              | 1 +
 src/Extension/Cryptography/Cipher/OpensslCipherKeyFactory.php    | 1 +
 src/Extension/Cryptography/Cryptographer.php                     | 1 +
 src/Extension/Cryptography/CryptographyExtension.php             | 1 +
 src/Extension/Cryptography/CryptographyMetadataEnricher.php      | 1 +
 src/Extension/Cryptography/CryptographyMiddleware.php            | 1 +
 src/Extension/Cryptography/DuplicateSubjectIdIdentifier.php      | 1 +
 src/Extension/Cryptography/MissingSubjectId.php                  | 1 +
 src/Extension/Cryptography/MissingSubjectIdForField.php          | 1 +
 src/Extension/Cryptography/SensitiveDataInfo.php                 | 1 +
 src/Extension/Cryptography/Store/CipherKeyNotExists.php          | 1 +
 src/Extension/Cryptography/Store/CipherKeyStore.php              | 1 +
 src/Extension/Cryptography/Store/InMemoryCipherKeyStore.php      | 1 +
 src/Extension/Cryptography/SubjectIdAndSensitiveDataConflict.php | 1 +
 src/Extension/Cryptography/SubjectIdFieldMapping.php             | 1 +
 src/Extension/Cryptography/SubjectIds.php                        | 1 +
 src/Extension/Cryptography/UnsupportedSubjectId.php              | 1 +
 src/Extension/Lifecycle/Attribute/PostExtract.php                | 1 +
 src/Extension/Lifecycle/Attribute/PostHydrate.php                | 1 +
 src/Extension/Lifecycle/Attribute/PreExtract.php                 | 1 +
 src/Extension/Lifecycle/Attribute/PreHydrate.php                 | 1 +
 src/Extension/Lifecycle/Lifecycle.php                            | 1 +
 src/Extension/Lifecycle/LifecycleExtension.php                   | 1 +
 src/Extension/Lifecycle/LifecycleMetadataEnricher.php            | 1 +
 src/Extension/Lifecycle/LifecycleMiddleware.php                  | 1 +
 src/Middleware/Middleware.php                                    | 1 +
 src/Middleware/NoMoreMiddleware.php                              | 1 +
 src/Middleware/Stack.php                                         | 1 +
 src/Middleware/TransformMiddleware.php                           | 1 +
 src/StackHydrator.php                                            | 1 +
 src/StackHydratorBuilder.php                                     | 1 +
 43 files changed, 43 insertions(+)

diff --git a/src/CoreExtension.php b/src/CoreExtension.php
index 81cce0df..9ff16064 100644
--- a/src/CoreExtension.php
+++ b/src/CoreExtension.php
@@ -7,6 +7,7 @@
 use Patchlevel\Hydrator\Guesser\BuiltInGuesser;
 use Patchlevel\Hydrator\Middleware\TransformMiddleware;
 
+/** @experimental */
 final class CoreExtension implements Extension
 {
     public function configure(StackHydratorBuilder $builder): void
diff --git a/src/Extension.php b/src/Extension.php
index 723e3052..3b0e83f1 100644
--- a/src/Extension.php
+++ b/src/Extension.php
@@ -4,6 +4,7 @@
 
 namespace Patchlevel\Hydrator;
 
+/** @experimental */
 interface Extension
 {
     public function configure(StackHydratorBuilder $builder): void;
diff --git a/src/Extension/Cryptography/Attribute/DataSubjectId.php b/src/Extension/Cryptography/Attribute/DataSubjectId.php
index 6c3443b6..8b65ac06 100644
--- a/src/Extension/Cryptography/Attribute/DataSubjectId.php
+++ b/src/Extension/Cryptography/Attribute/DataSubjectId.php
@@ -6,6 +6,7 @@
 
 use Attribute;
 
+/** @experimental */
 #[Attribute(Attribute::TARGET_PROPERTY)]
 final class DataSubjectId
 {
diff --git a/src/Extension/Cryptography/Attribute/SensitiveData.php b/src/Extension/Cryptography/Attribute/SensitiveData.php
index 2e0c734e..4e004ab5 100644
--- a/src/Extension/Cryptography/Attribute/SensitiveData.php
+++ b/src/Extension/Cryptography/Attribute/SensitiveData.php
@@ -7,6 +7,7 @@
 use Attribute;
 use InvalidArgumentException;
 
+/** @experimental */
 #[Attribute(Attribute::TARGET_PROPERTY)]
 final class SensitiveData
 {
diff --git a/src/Extension/Cryptography/BaseCryptographer.php b/src/Extension/Cryptography/BaseCryptographer.php
index 1419249a..8769c6b2 100644
--- a/src/Extension/Cryptography/BaseCryptographer.php
+++ b/src/Extension/Cryptography/BaseCryptographer.php
@@ -20,6 +20,7 @@
 use function is_array;
 
 /**
+ * @experimental
  * @phpstan-type EncryptedDataV1 array{
  *     __enc: 'v1',
  *     data: non-empty-string,
diff --git a/src/Extension/Cryptography/Cipher/Cipher.php b/src/Extension/Cryptography/Cipher/Cipher.php
index 9652c851..03f38ec8 100644
--- a/src/Extension/Cryptography/Cipher/Cipher.php
+++ b/src/Extension/Cryptography/Cipher/Cipher.php
@@ -4,6 +4,7 @@
 
 namespace Patchlevel\Hydrator\Extension\Cryptography\Cipher;
 
+/** @experimental */
 interface Cipher
 {
     /**
diff --git a/src/Extension/Cryptography/Cipher/CipherKey.php b/src/Extension/Cryptography/Cipher/CipherKey.php
index 52e7e354..ced9c9aa 100644
--- a/src/Extension/Cryptography/Cipher/CipherKey.php
+++ b/src/Extension/Cryptography/Cipher/CipherKey.php
@@ -4,6 +4,7 @@
 
 namespace Patchlevel\Hydrator\Extension\Cryptography\Cipher;
 
+/** @experimental */
 final class CipherKey
 {
     /**
diff --git a/src/Extension/Cryptography/Cipher/CipherKeyFactory.php b/src/Extension/Cryptography/Cipher/CipherKeyFactory.php
index 2eeb4935..85050f1f 100644
--- a/src/Extension/Cryptography/Cipher/CipherKeyFactory.php
+++ b/src/Extension/Cryptography/Cipher/CipherKeyFactory.php
@@ -4,6 +4,7 @@
 
 namespace Patchlevel\Hydrator\Extension\Cryptography\Cipher;
 
+/** @experimental */
 interface CipherKeyFactory
 {
     /** @throws CreateCipherKeyFailed */
diff --git a/src/Extension/Cryptography/Cipher/CreateCipherKeyFailed.php b/src/Extension/Cryptography/Cipher/CreateCipherKeyFailed.php
index b54acedc..60f2fcf2 100644
--- a/src/Extension/Cryptography/Cipher/CreateCipherKeyFailed.php
+++ b/src/Extension/Cryptography/Cipher/CreateCipherKeyFailed.php
@@ -7,6 +7,7 @@
 use Patchlevel\Hydrator\HydratorException;
 use RuntimeException;
 
+/** @experimental */
 final class CreateCipherKeyFailed extends RuntimeException implements HydratorException
 {
     public function __construct()
diff --git a/src/Extension/Cryptography/Cipher/DecryptionFailed.php b/src/Extension/Cryptography/Cipher/DecryptionFailed.php
index 56e890d8..8b7059e8 100644
--- a/src/Extension/Cryptography/Cipher/DecryptionFailed.php
+++ b/src/Extension/Cryptography/Cipher/DecryptionFailed.php
@@ -7,6 +7,7 @@
 use Patchlevel\Hydrator\HydratorException;
 use RuntimeException;
 
+/** @experimental */
 final class DecryptionFailed extends RuntimeException implements HydratorException
 {
     public function __construct()
diff --git a/src/Extension/Cryptography/Cipher/EncryptionFailed.php b/src/Extension/Cryptography/Cipher/EncryptionFailed.php
index 43f19481..65bd1fb4 100644
--- a/src/Extension/Cryptography/Cipher/EncryptionFailed.php
+++ b/src/Extension/Cryptography/Cipher/EncryptionFailed.php
@@ -7,6 +7,7 @@
 use Patchlevel\Hydrator\HydratorException;
 use RuntimeException;
 
+/** @experimental */
 final class EncryptionFailed extends RuntimeException implements HydratorException
 {
     public function __construct()
diff --git a/src/Extension/Cryptography/Cipher/MethodNotSupported.php b/src/Extension/Cryptography/Cipher/MethodNotSupported.php
index d3512904..2b24978e 100644
--- a/src/Extension/Cryptography/Cipher/MethodNotSupported.php
+++ b/src/Extension/Cryptography/Cipher/MethodNotSupported.php
@@ -9,6 +9,7 @@
 
 use function sprintf;
 
+/** @experimental */
 final class MethodNotSupported extends RuntimeException implements HydratorException
 {
     public function __construct(string $method)
diff --git a/src/Extension/Cryptography/Cipher/OpensslCipher.php b/src/Extension/Cryptography/Cipher/OpensslCipher.php
index e37235a5..2fd55afa 100644
--- a/src/Extension/Cryptography/Cipher/OpensslCipher.php
+++ b/src/Extension/Cryptography/Cipher/OpensslCipher.php
@@ -15,6 +15,7 @@
 
 use const JSON_THROW_ON_ERROR;
 
+/** @experimental */
 final class OpensslCipher implements Cipher
 {
     /** @return non-empty-string */
diff --git a/src/Extension/Cryptography/Cipher/OpensslCipherKeyFactory.php b/src/Extension/Cryptography/Cipher/OpensslCipherKeyFactory.php
index 3e30a638..67f1a5b0 100644
--- a/src/Extension/Cryptography/Cipher/OpensslCipherKeyFactory.php
+++ b/src/Extension/Cryptography/Cipher/OpensslCipherKeyFactory.php
@@ -11,6 +11,7 @@
 use function openssl_get_cipher_methods;
 use function openssl_random_pseudo_bytes;
 
+/** @experimental */
 final class OpensslCipherKeyFactory implements CipherKeyFactory
 {
     public const DEFAULT_METHOD = 'aes128';
diff --git a/src/Extension/Cryptography/Cryptographer.php b/src/Extension/Cryptography/Cryptographer.php
index b540ec7d..054dc4a6 100644
--- a/src/Extension/Cryptography/Cryptographer.php
+++ b/src/Extension/Cryptography/Cryptographer.php
@@ -8,6 +8,7 @@
 use Patchlevel\Hydrator\Extension\Cryptography\Cipher\EncryptionFailed;
 use Patchlevel\Hydrator\Extension\Cryptography\Store\CipherKeyNotExists;
 
+/** @experimental */
 interface Cryptographer
 {
     /** @throws EncryptionFailed */
diff --git a/src/Extension/Cryptography/CryptographyExtension.php b/src/Extension/Cryptography/CryptographyExtension.php
index 0274a9d6..ea8a6a21 100644
--- a/src/Extension/Cryptography/CryptographyExtension.php
+++ b/src/Extension/Cryptography/CryptographyExtension.php
@@ -7,6 +7,7 @@
 use Patchlevel\Hydrator\Extension;
 use Patchlevel\Hydrator\StackHydratorBuilder;
 
+/** @experimental */
 final class CryptographyExtension implements Extension
 {
     public function __construct(
diff --git a/src/Extension/Cryptography/CryptographyMetadataEnricher.php b/src/Extension/Cryptography/CryptographyMetadataEnricher.php
index 6357d5a4..794ccd0f 100644
--- a/src/Extension/Cryptography/CryptographyMetadataEnricher.php
+++ b/src/Extension/Cryptography/CryptographyMetadataEnricher.php
@@ -12,6 +12,7 @@
 
 use function array_key_exists;
 
+/** @experimental */
 final class CryptographyMetadataEnricher implements MetadataEnricher
 {
     public function enrich(ClassMetadata $classMetadata): void
diff --git a/src/Extension/Cryptography/CryptographyMiddleware.php b/src/Extension/Cryptography/CryptographyMiddleware.php
index 304ce220..60616e59 100644
--- a/src/Extension/Cryptography/CryptographyMiddleware.php
+++ b/src/Extension/Cryptography/CryptographyMiddleware.php
@@ -19,6 +19,7 @@
 use function is_int;
 use function is_string;
 
+/** @experimental */
 final class CryptographyMiddleware implements Middleware
 {
     public function __construct(
diff --git a/src/Extension/Cryptography/DuplicateSubjectIdIdentifier.php b/src/Extension/Cryptography/DuplicateSubjectIdIdentifier.php
index 91d3a034..6a93822c 100644
--- a/src/Extension/Cryptography/DuplicateSubjectIdIdentifier.php
+++ b/src/Extension/Cryptography/DuplicateSubjectIdIdentifier.php
@@ -9,6 +9,7 @@
 
 use function sprintf;
 
+/** @experimental */
 final class DuplicateSubjectIdIdentifier extends RuntimeException implements MetadataException
 {
     /** @param class-string $class */
diff --git a/src/Extension/Cryptography/MissingSubjectId.php b/src/Extension/Cryptography/MissingSubjectId.php
index df8a7c32..d09db6c7 100644
--- a/src/Extension/Cryptography/MissingSubjectId.php
+++ b/src/Extension/Cryptography/MissingSubjectId.php
@@ -9,6 +9,7 @@
 
 use function sprintf;
 
+/** @experimental */
 final class MissingSubjectId extends RuntimeException implements HydratorException
 {
     public function __construct(string $name)
diff --git a/src/Extension/Cryptography/MissingSubjectIdForField.php b/src/Extension/Cryptography/MissingSubjectIdForField.php
index afc0a304..a74f1986 100644
--- a/src/Extension/Cryptography/MissingSubjectIdForField.php
+++ b/src/Extension/Cryptography/MissingSubjectIdForField.php
@@ -9,6 +9,7 @@
 
 use function sprintf;
 
+/** @experimental */
 final class MissingSubjectIdForField extends RuntimeException implements HydratorException
 {
     /** @param class-string $class */
diff --git a/src/Extension/Cryptography/SensitiveDataInfo.php b/src/Extension/Cryptography/SensitiveDataInfo.php
index 7f00c3f4..af3990be 100644
--- a/src/Extension/Cryptography/SensitiveDataInfo.php
+++ b/src/Extension/Cryptography/SensitiveDataInfo.php
@@ -4,6 +4,7 @@
 
 namespace Patchlevel\Hydrator\Extension\Cryptography;
 
+/** @experimental */
 final class SensitiveDataInfo
 {
     public function __construct(
diff --git a/src/Extension/Cryptography/Store/CipherKeyNotExists.php b/src/Extension/Cryptography/Store/CipherKeyNotExists.php
index 1b6d7adc..8679caf9 100644
--- a/src/Extension/Cryptography/Store/CipherKeyNotExists.php
+++ b/src/Extension/Cryptography/Store/CipherKeyNotExists.php
@@ -9,6 +9,7 @@
 
 use function sprintf;
 
+/** @experimental */
 final class CipherKeyNotExists extends RuntimeException implements HydratorException
 {
     public function __construct(string $id)
diff --git a/src/Extension/Cryptography/Store/CipherKeyStore.php b/src/Extension/Cryptography/Store/CipherKeyStore.php
index 5f0541f9..fe589f28 100644
--- a/src/Extension/Cryptography/Store/CipherKeyStore.php
+++ b/src/Extension/Cryptography/Store/CipherKeyStore.php
@@ -6,6 +6,7 @@
 
 use Patchlevel\Hydrator\Extension\Cryptography\Cipher\CipherKey;
 
+/** @experimental */
 interface CipherKeyStore
 {
     /** @throws CipherKeyNotExists */
diff --git a/src/Extension/Cryptography/Store/InMemoryCipherKeyStore.php b/src/Extension/Cryptography/Store/InMemoryCipherKeyStore.php
index aa0ea334..dd328233 100644
--- a/src/Extension/Cryptography/Store/InMemoryCipherKeyStore.php
+++ b/src/Extension/Cryptography/Store/InMemoryCipherKeyStore.php
@@ -6,6 +6,7 @@
 
 use Patchlevel\Hydrator\Extension\Cryptography\Cipher\CipherKey;
 
+/** @experimental */
 final class InMemoryCipherKeyStore implements CipherKeyStore
 {
     /** @var array<string, CipherKey> */
diff --git a/src/Extension/Cryptography/SubjectIdAndSensitiveDataConflict.php b/src/Extension/Cryptography/SubjectIdAndSensitiveDataConflict.php
index 265ff6c0..69cdca84 100644
--- a/src/Extension/Cryptography/SubjectIdAndSensitiveDataConflict.php
+++ b/src/Extension/Cryptography/SubjectIdAndSensitiveDataConflict.php
@@ -9,6 +9,7 @@
 
 use function sprintf;
 
+/** @experimental */
 final class SubjectIdAndSensitiveDataConflict extends RuntimeException implements MetadataException
 {
     /** @param class-string $class */
diff --git a/src/Extension/Cryptography/SubjectIdFieldMapping.php b/src/Extension/Cryptography/SubjectIdFieldMapping.php
index 5aa9b9b8..ffef5c47 100644
--- a/src/Extension/Cryptography/SubjectIdFieldMapping.php
+++ b/src/Extension/Cryptography/SubjectIdFieldMapping.php
@@ -4,6 +4,7 @@
 
 namespace Patchlevel\Hydrator\Extension\Cryptography;
 
+/** @experimental */
 final class SubjectIdFieldMapping
 {
     /** @param array<string, string> $nameToField */
diff --git a/src/Extension/Cryptography/SubjectIds.php b/src/Extension/Cryptography/SubjectIds.php
index 12d6d730..ca1df081 100644
--- a/src/Extension/Cryptography/SubjectIds.php
+++ b/src/Extension/Cryptography/SubjectIds.php
@@ -6,6 +6,7 @@
 
 use function array_merge;
 
+/** @experimental */
 final class SubjectIds
 {
     /** @param array<string, string> $subjectIds */
diff --git a/src/Extension/Cryptography/UnsupportedSubjectId.php b/src/Extension/Cryptography/UnsupportedSubjectId.php
index 13fb8e43..ad739a38 100644
--- a/src/Extension/Cryptography/UnsupportedSubjectId.php
+++ b/src/Extension/Cryptography/UnsupportedSubjectId.php
@@ -10,6 +10,7 @@
 use function get_debug_type;
 use function sprintf;
 
+/** @experimental */
 final class UnsupportedSubjectId extends RuntimeException implements HydratorException
 {
     public function __construct(string $class, string $fieldName, mixed $subjectId)
diff --git a/src/Extension/Lifecycle/Attribute/PostExtract.php b/src/Extension/Lifecycle/Attribute/PostExtract.php
index 6cd5810e..afb09110 100644
--- a/src/Extension/Lifecycle/Attribute/PostExtract.php
+++ b/src/Extension/Lifecycle/Attribute/PostExtract.php
@@ -6,6 +6,7 @@
 
 use Attribute;
 
+/** @experimental */
 #[Attribute(Attribute::TARGET_METHOD)]
 final class PostExtract
 {
diff --git a/src/Extension/Lifecycle/Attribute/PostHydrate.php b/src/Extension/Lifecycle/Attribute/PostHydrate.php
index d15bba32..f4599c6c 100644
--- a/src/Extension/Lifecycle/Attribute/PostHydrate.php
+++ b/src/Extension/Lifecycle/Attribute/PostHydrate.php
@@ -6,6 +6,7 @@
 
 use Attribute;
 
+/** @experimental */
 #[Attribute(Attribute::TARGET_METHOD)]
 final class PostHydrate
 {
diff --git a/src/Extension/Lifecycle/Attribute/PreExtract.php b/src/Extension/Lifecycle/Attribute/PreExtract.php
index 6d223f54..b42ac169 100644
--- a/src/Extension/Lifecycle/Attribute/PreExtract.php
+++ b/src/Extension/Lifecycle/Attribute/PreExtract.php
@@ -6,6 +6,7 @@
 
 use Attribute;
 
+/** @experimental */
 #[Attribute(Attribute::TARGET_METHOD)]
 final class PreExtract
 {
diff --git a/src/Extension/Lifecycle/Attribute/PreHydrate.php b/src/Extension/Lifecycle/Attribute/PreHydrate.php
index bd4f0bb7..5ecb92bb 100644
--- a/src/Extension/Lifecycle/Attribute/PreHydrate.php
+++ b/src/Extension/Lifecycle/Attribute/PreHydrate.php
@@ -6,6 +6,7 @@
 
 use Attribute;
 
+/** @experimental */
 #[Attribute(Attribute::TARGET_METHOD)]
 final class PreHydrate
 {
diff --git a/src/Extension/Lifecycle/Lifecycle.php b/src/Extension/Lifecycle/Lifecycle.php
index 0cd9522b..e5f15e1e 100644
--- a/src/Extension/Lifecycle/Lifecycle.php
+++ b/src/Extension/Lifecycle/Lifecycle.php
@@ -4,6 +4,7 @@
 
 namespace Patchlevel\Hydrator\Extension\Lifecycle;
 
+/** @experimental */
 final readonly class Lifecycle
 {
     public function __construct(
diff --git a/src/Extension/Lifecycle/LifecycleExtension.php b/src/Extension/Lifecycle/LifecycleExtension.php
index 1bfa0d5c..47bc6113 100644
--- a/src/Extension/Lifecycle/LifecycleExtension.php
+++ b/src/Extension/Lifecycle/LifecycleExtension.php
@@ -7,6 +7,7 @@
 use Patchlevel\Hydrator\Extension;
 use Patchlevel\Hydrator\StackHydratorBuilder;
 
+/** @experimental */
 final readonly class LifecycleExtension implements Extension
 {
     public function configure(StackHydratorBuilder $builder): void
diff --git a/src/Extension/Lifecycle/LifecycleMetadataEnricher.php b/src/Extension/Lifecycle/LifecycleMetadataEnricher.php
index 332e8257..4222ac6b 100644
--- a/src/Extension/Lifecycle/LifecycleMetadataEnricher.php
+++ b/src/Extension/Lifecycle/LifecycleMetadataEnricher.php
@@ -14,6 +14,7 @@
 
 use function sprintf;
 
+/** @experimental */
 final class LifecycleMetadataEnricher implements MetadataEnricher
 {
     public function enrich(ClassMetadata $classMetadata): void
diff --git a/src/Extension/Lifecycle/LifecycleMiddleware.php b/src/Extension/Lifecycle/LifecycleMiddleware.php
index 05e51cac..ed9db0da 100644
--- a/src/Extension/Lifecycle/LifecycleMiddleware.php
+++ b/src/Extension/Lifecycle/LifecycleMiddleware.php
@@ -10,6 +10,7 @@
 
 use function assert;
 
+/** @experimental */
 final class LifecycleMiddleware implements Middleware
 {
     /**
diff --git a/src/Middleware/Middleware.php b/src/Middleware/Middleware.php
index 106dab61..aa6074a5 100644
--- a/src/Middleware/Middleware.php
+++ b/src/Middleware/Middleware.php
@@ -6,6 +6,7 @@
 
 use Patchlevel\Hydrator\Metadata\ClassMetadata;
 
+/** @experimental */
 interface Middleware
 {
     /**
diff --git a/src/Middleware/NoMoreMiddleware.php b/src/Middleware/NoMoreMiddleware.php
index 8203ab3c..4d063998 100644
--- a/src/Middleware/NoMoreMiddleware.php
+++ b/src/Middleware/NoMoreMiddleware.php
@@ -7,6 +7,7 @@
 use Patchlevel\Hydrator\HydratorException;
 use RuntimeException;
 
+/** @experimental */
 final class NoMoreMiddleware extends RuntimeException implements HydratorException
 {
     public function __construct()
diff --git a/src/Middleware/Stack.php b/src/Middleware/Stack.php
index 7a47f627..6be11ea3 100644
--- a/src/Middleware/Stack.php
+++ b/src/Middleware/Stack.php
@@ -4,6 +4,7 @@
 
 namespace Patchlevel\Hydrator\Middleware;
 
+/** @experimental */
 final class Stack
 {
     private int $index = 0;
diff --git a/src/Middleware/TransformMiddleware.php b/src/Middleware/TransformMiddleware.php
index c180d17c..c90d1fcf 100644
--- a/src/Middleware/TransformMiddleware.php
+++ b/src/Middleware/TransformMiddleware.php
@@ -17,6 +17,7 @@
 use function array_values;
 use function spl_object_id;
 
+/** @experimental */
 final class TransformMiddleware implements Middleware
 {
     /** @var array<int, class-string> */
diff --git a/src/StackHydrator.php b/src/StackHydrator.php
index bfe593bb..f0bab583 100644
--- a/src/StackHydrator.php
+++ b/src/StackHydrator.php
@@ -18,6 +18,7 @@
 
 use const PHP_VERSION_ID;
 
+/** @experimental */
 final class StackHydrator implements HydratorWithContext
 {
     /** @var array<class-string, ClassMetadata> */
diff --git a/src/StackHydratorBuilder.php b/src/StackHydratorBuilder.php
index 39c5b9b6..4d5e72f7 100644
--- a/src/StackHydratorBuilder.php
+++ b/src/StackHydratorBuilder.php
@@ -18,6 +18,7 @@
 use function array_merge;
 use function krsort;
 
+/** @experimental */
 final class StackHydratorBuilder
 {
     private bool $defaultLazy = false;