diff --git a/composer.json b/composer.json
index ed9bda8e66125..ee17718abd750 100644
--- a/composer.json
+++ b/composer.json
@@ -47,7 +47,7 @@
         "psr/http-message": "^1.0|^2.0",
         "psr/link": "^1.1|^2.0",
         "psr/log": "^1|^2|^3",
-        "symfony/contracts": "^3.5",
+        "symfony/contracts": "^3.6",
         "symfony/polyfill-ctype": "~1.8",
         "symfony/polyfill-intl-grapheme": "~1.0",
         "symfony/polyfill-intl-icu": "~1.0",
@@ -218,7 +218,7 @@
             "url": "src/Symfony/Contracts",
             "options": {
                 "versions": {
-                    "symfony/contracts": "3.5.x-dev"
+                    "symfony/contracts": "3.6.x-dev"
                 }
             }
         },
diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
index e2d0888dbd7e6..353fd19428363 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
@@ -208,6 +208,7 @@
 use Symfony\Component\Yaml\Yaml;
 use Symfony\Contracts\Cache\CacheInterface;
 use Symfony\Contracts\Cache\CallbackInterface;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 use Symfony\Contracts\Cache\TagAwareCacheInterface;
 use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 use Symfony\Contracts\HttpClient\HttpClientInterface;
@@ -2576,6 +2577,10 @@ private function registerCacheConfiguration(array $config, ContainerBuilder $con
                 $container->registerAliasForArgument($tagAwareId, TagAwareCacheInterface::class, $pool['name'] ?? $name);
                 $container->registerAliasForArgument($name, CacheInterface::class, $pool['name'] ?? $name);
                 $container->registerAliasForArgument($name, CacheItemPoolInterface::class, $pool['name'] ?? $name);
+
+                if (interface_exists(NamespacedPoolInterface::class)) {
+                    $container->registerAliasForArgument($name, NamespacedPoolInterface::class, $pool['name'] ?? $name);
+                }
             }
 
             $definition->setPublic($pool['public']);
diff --git a/src/Symfony/Bundle/WebProfilerBundle/Resources/views/Collector/cache.html.twig b/src/Symfony/Bundle/WebProfilerBundle/Resources/views/Collector/cache.html.twig
index d0bc96868e8e6..217ad78f2b412 100644
--- a/src/Symfony/Bundle/WebProfilerBundle/Resources/views/Collector/cache.html.twig
+++ b/src/Symfony/Bundle/WebProfilerBundle/Resources/views/Collector/cache.html.twig
@@ -93,7 +93,7 @@
                                     <tr>
                                         <td class="font-normal text-small text-muted nowrap">{{ loop.index }}</td>
                                         <td class="nowrap">{{ '%0.2f'|format((call.end - call.start) * 1000) }} ms</td>
-                                        <td class="nowrap">{{ call.name }}()</td>
+                                        <td class="nowrap">{{ call.name }}({{ call.namespace|default('') }})</td>
                                         <td>{{ profiler_dump(call.value.result, maxDepth=2) }}</td>
                                     </tr>
                                 {% endfor %}
diff --git a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
index 8cd2218dc06c1..2b4bc8b22440f 100644
--- a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
@@ -19,11 +19,12 @@
 use Symfony\Component\Cache\Traits\AbstractAdapterTrait;
 use Symfony\Component\Cache\Traits\ContractsTrait;
 use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 
 /**
  * @author Nicolas Grekas <p@tchwork.com>
  */
-abstract class AbstractAdapter implements AdapterInterface, CacheInterface, LoggerAwareInterface, ResettableInterface
+abstract class AbstractAdapter implements AdapterInterface, CacheInterface, NamespacedPoolInterface, LoggerAwareInterface, ResettableInterface
 {
     use AbstractAdapterTrait;
     use ContractsTrait;
@@ -37,7 +38,19 @@ abstract class AbstractAdapter implements AdapterInterface, CacheInterface, Logg
 
     protected function __construct(string $namespace = '', int $defaultLifetime = 0)
     {
-        $this->namespace = '' === $namespace ? '' : CacheItem::validateKey($namespace).static::NS_SEPARATOR;
+        if ('' !== $namespace) {
+            if (str_contains($namespace, static::NS_SEPARATOR)) {
+                if (str_contains($namespace, static::NS_SEPARATOR.static::NS_SEPARATOR)) {
+                    throw new InvalidArgumentException(\sprintf('Cache namespace "%s" contains empty sub-namespace.', $namespace));
+                }
+                CacheItem::validateKey(str_replace(static::NS_SEPARATOR, '', $namespace));
+            } else {
+                CacheItem::validateKey($namespace);
+            }
+            $this->namespace = $namespace.static::NS_SEPARATOR;
+        }
+        $this->rootNamespace = $this->namespace;
+
         $this->defaultLifetime = $defaultLifetime;
         if (null !== $this->maxIdLength && \strlen($namespace) > $this->maxIdLength - 24) {
             throw new InvalidArgumentException(\sprintf('Namespace must be %d chars max, %d given ("%s").', $this->maxIdLength - 24, \strlen($namespace), $namespace));
@@ -118,7 +131,7 @@ public static function createConnection(#[\SensitiveParameter] string $dsn, arra
             return MemcachedAdapter::createConnection($dsn, $options);
         }
         if (str_starts_with($dsn, 'couchbase:')) {
-            if (class_exists('CouchbaseBucket') && CouchbaseBucketAdapter::isSupported()) {
+            if (class_exists(\CouchbaseBucket::class) && CouchbaseBucketAdapter::isSupported()) {
                 return CouchbaseBucketAdapter::createConnection($dsn, $options);
             }
 
@@ -159,7 +172,7 @@ public function commit(): bool
                     $v = $values[$id];
                     $type = get_debug_type($v);
                     $message = \sprintf('Failed to save key "{key}" of type %s%s', $type, $e instanceof \Exception ? ': '.$e->getMessage() : '.');
-                    CacheItem::log($this->logger, $message, ['key' => substr($id, \strlen($this->namespace)), 'exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
+                    CacheItem::log($this->logger, $message, ['key' => substr($id, \strlen($this->rootNamespace)), 'exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
                 }
             } else {
                 foreach ($values as $id => $v) {
@@ -182,7 +195,7 @@ public function commit(): bool
                 $ok = false;
                 $type = get_debug_type($v);
                 $message = \sprintf('Failed to save key "{key}" of type %s%s', $type, $e instanceof \Exception ? ': '.$e->getMessage() : '.');
-                CacheItem::log($this->logger, $message, ['key' => substr($id, \strlen($this->namespace)), 'exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
+                CacheItem::log($this->logger, $message, ['key' => substr($id, \strlen($this->rootNamespace)), 'exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
             }
         }
 
diff --git a/src/Symfony/Component/Cache/Adapter/AbstractTagAwareAdapter.php b/src/Symfony/Component/Cache/Adapter/AbstractTagAwareAdapter.php
index 822c30f09bdbd..23db2b6eb8c8a 100644
--- a/src/Symfony/Component/Cache/Adapter/AbstractTagAwareAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/AbstractTagAwareAdapter.php
@@ -17,6 +17,7 @@
 use Symfony\Component\Cache\ResettableInterface;
 use Symfony\Component\Cache\Traits\AbstractAdapterTrait;
 use Symfony\Component\Cache\Traits\ContractsTrait;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 use Symfony\Contracts\Cache\TagAwareCacheInterface;
 
 /**
@@ -30,16 +31,33 @@
  *
  * @internal
  */
-abstract class AbstractTagAwareAdapter implements TagAwareAdapterInterface, TagAwareCacheInterface, LoggerAwareInterface, ResettableInterface
+abstract class AbstractTagAwareAdapter implements TagAwareAdapterInterface, TagAwareCacheInterface, AdapterInterface, NamespacedPoolInterface, LoggerAwareInterface, ResettableInterface
 {
     use AbstractAdapterTrait;
     use ContractsTrait;
 
+    /**
+     * @internal
+     */
+    protected const NS_SEPARATOR = ':';
+
     private const TAGS_PREFIX = "\1tags\1";
 
     protected function __construct(string $namespace = '', int $defaultLifetime = 0)
     {
-        $this->namespace = '' === $namespace ? '' : CacheItem::validateKey($namespace).':';
+        if ('' !== $namespace) {
+            if (str_contains($namespace, static::NS_SEPARATOR)) {
+                if (str_contains($namespace, static::NS_SEPARATOR.static::NS_SEPARATOR)) {
+                    throw new InvalidArgumentException(\sprintf('Cache namespace "%s" contains empty sub-namespace.', $namespace));
+                }
+                CacheItem::validateKey(str_replace(static::NS_SEPARATOR, '', $namespace));
+            } else {
+                CacheItem::validateKey($namespace);
+            }
+            $this->namespace = $namespace.static::NS_SEPARATOR;
+        }
+        $this->rootNamespace = $this->namespace;
+
         $this->defaultLifetime = $defaultLifetime;
         if (null !== $this->maxIdLength && \strlen($namespace) > $this->maxIdLength - 24) {
             throw new InvalidArgumentException(\sprintf('Namespace must be %d chars max, %d given ("%s").', $this->maxIdLength - 24, \strlen($namespace), $namespace));
@@ -70,7 +88,7 @@ static function ($key, $value, $isHit) {
             CacheItem::class
         );
         self::$mergeByLifetime ??= \Closure::bind(
-            static function ($deferred, &$expiredIds, $getId, $tagPrefix, $defaultLifetime) {
+            static function ($deferred, &$expiredIds, $getId, $tagPrefix, $defaultLifetime, $rootNamespace) {
                 $byLifetime = [];
                 $now = microtime(true);
                 $expiredIds = [];
@@ -102,10 +120,10 @@ static function ($deferred, &$expiredIds, $getId, $tagPrefix, $defaultLifetime)
                     $value['tag-operations'] = ['add' => [], 'remove' => []];
                     $oldTags = $item->metadata[CacheItem::METADATA_TAGS] ?? [];
                     foreach (array_diff_key($value['tags'], $oldTags) as $addedTag) {
-                        $value['tag-operations']['add'][] = $getId($tagPrefix.$addedTag);
+                        $value['tag-operations']['add'][] = $getId($tagPrefix.$addedTag, $rootNamespace);
                     }
                     foreach (array_diff_key($oldTags, $value['tags']) as $removedTag) {
-                        $value['tag-operations']['remove'][] = $getId($tagPrefix.$removedTag);
+                        $value['tag-operations']['remove'][] = $getId($tagPrefix.$removedTag, $rootNamespace);
                     }
                     $value['tags'] = array_keys($value['tags']);
 
@@ -168,7 +186,7 @@ protected function doDeleteYieldTags(array $ids): iterable
     public function commit(): bool
     {
         $ok = true;
-        $byLifetime = (self::$mergeByLifetime)($this->deferred, $expiredIds, $this->getId(...), self::TAGS_PREFIX, $this->defaultLifetime);
+        $byLifetime = (self::$mergeByLifetime)($this->deferred, $expiredIds, $this->getId(...), self::TAGS_PREFIX, $this->defaultLifetime, $this->rootNamespace);
         $retry = $this->deferred = [];
 
         if ($expiredIds) {
@@ -195,7 +213,7 @@ public function commit(): bool
                     $v = $values[$id];
                     $type = get_debug_type($v);
                     $message = \sprintf('Failed to save key "{key}" of type %s%s', $type, $e instanceof \Exception ? ': '.$e->getMessage() : '.');
-                    CacheItem::log($this->logger, $message, ['key' => substr($id, \strlen($this->namespace)), 'exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
+                    CacheItem::log($this->logger, $message, ['key' => substr($id, \strlen($this->rootNamespace)), 'exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
                 }
             } else {
                 foreach ($values as $id => $v) {
@@ -219,7 +237,7 @@ public function commit(): bool
                 $ok = false;
                 $type = get_debug_type($v);
                 $message = \sprintf('Failed to save key "{key}" of type %s%s', $type, $e instanceof \Exception ? ': '.$e->getMessage() : '.');
-                CacheItem::log($this->logger, $message, ['key' => substr($id, \strlen($this->namespace)), 'exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
+                CacheItem::log($this->logger, $message, ['key' => substr($id, \strlen($this->rootNamespace)), 'exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
             }
         }
 
@@ -244,7 +262,7 @@ public function deleteItems(array $keys): bool
         try {
             foreach ($this->doDeleteYieldTags(array_values($ids)) as $id => $tags) {
                 foreach ($tags as $tag) {
-                    $tagData[$this->getId(self::TAGS_PREFIX.$tag)][] = $id;
+                    $tagData[$this->getId(self::TAGS_PREFIX.$tag, $this->rootNamespace)][] = $id;
                 }
             }
         } catch (\Exception) {
@@ -283,7 +301,7 @@ public function invalidateTags(array $tags): bool
 
         $tagIds = [];
         foreach (array_unique($tags) as $tag) {
-            $tagIds[] = $this->getId(self::TAGS_PREFIX.$tag);
+            $tagIds[] = $this->getId(self::TAGS_PREFIX.$tag, $this->rootNamespace);
         }
 
         try {
diff --git a/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php b/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
index 7b92387742894..7deb9dc6e2187 100644
--- a/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
@@ -19,6 +19,7 @@
 use Symfony\Component\Cache\Exception\InvalidArgumentException;
 use Symfony\Component\Cache\ResettableInterface;
 use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 
 /**
  * An in-memory cache storage.
@@ -27,13 +28,14 @@
  *
  * @author Nicolas Grekas <p@tchwork.com>
  */
-class ArrayAdapter implements AdapterInterface, CacheInterface, LoggerAwareInterface, ResettableInterface
+class ArrayAdapter implements AdapterInterface, CacheInterface, NamespacedPoolInterface, LoggerAwareInterface, ResettableInterface
 {
     use LoggerAwareTrait;
 
     private array $values = [];
     private array $tags = [];
     private array $expiries = [];
+    private array $subPools = [];
 
     private static \Closure $createCacheItem;
 
@@ -226,16 +228,38 @@ public function clear(string $prefix = ''): bool
                 }
             }
 
-            if ($this->values) {
-                return true;
-            }
+            return true;
+        }
+
+        foreach ($this->subPools as $pool) {
+            $pool->clear();
         }
 
-        $this->values = $this->tags = $this->expiries = [];
+        $this->subPools = $this->values = $this->tags = $this->expiries = [];
 
         return true;
     }
 
+    public function withSubNamespace(string $namespace): static
+    {
+        CacheItem::validateKey($namespace);
+
+        $subPools = $this->subPools;
+
+        if (isset($subPools[$namespace])) {
+            return $subPools[$namespace];
+        }
+
+        $this->subPools = [];
+        $clone = clone $this;
+        $clone->clear();
+
+        $subPools[$namespace] = $clone;
+        $this->subPools = $subPools;
+
+        return $clone;
+    }
+
     /**
      * Returns all cached values, with cache miss as null.
      */
@@ -263,6 +287,13 @@ public function reset(): void
         $this->clear();
     }
 
+    public function __clone()
+    {
+        foreach ($this->subPools as $i => $pool) {
+            $this->subPools[$i] = clone $pool;
+        }
+    }
+
     private function generateItems(array $keys, float $now, \Closure $f): \Generator
     {
         foreach ($keys as $i => $key) {
diff --git a/src/Symfony/Component/Cache/Adapter/ChainAdapter.php b/src/Symfony/Component/Cache/Adapter/ChainAdapter.php
index 09fcfdcc07b88..c27faeb111617 100644
--- a/src/Symfony/Component/Cache/Adapter/ChainAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ChainAdapter.php
@@ -14,11 +14,13 @@
 use Psr\Cache\CacheItemInterface;
 use Psr\Cache\CacheItemPoolInterface;
 use Symfony\Component\Cache\CacheItem;
+use Symfony\Component\Cache\Exception\BadMethodCallException;
 use Symfony\Component\Cache\Exception\InvalidArgumentException;
 use Symfony\Component\Cache\PruneableInterface;
 use Symfony\Component\Cache\ResettableInterface;
 use Symfony\Component\Cache\Traits\ContractsTrait;
 use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 use Symfony\Contracts\Service\ResetInterface;
 
 /**
@@ -29,7 +31,7 @@
  *
  * @author Kévin Dunglas <dunglas@gmail.com>
  */
-class ChainAdapter implements AdapterInterface, CacheInterface, PruneableInterface, ResettableInterface
+class ChainAdapter implements AdapterInterface, CacheInterface, NamespacedPoolInterface, PruneableInterface, ResettableInterface
 {
     use ContractsTrait;
 
@@ -280,6 +282,23 @@ public function prune(): bool
         return $pruned;
     }
 
+    public function withSubNamespace(string $namespace): static
+    {
+        $clone = clone $this;
+        $adapters = [];
+
+        foreach ($this->adapters as $adapter) {
+            if (!$adapter instanceof NamespacedPoolInterface) {
+                throw new BadMethodCallException('All adapters must implement NamespacedPoolInterface to support namespaces.');
+            }
+
+            $adapters[] = $adapter->withSubNamespace($namespace);
+        }
+        $clone->adapters = $adapters;
+
+        return $clone;
+    }
+
     public function reset(): void
     {
         foreach ($this->adapters as $adapter) {
diff --git a/src/Symfony/Component/Cache/Adapter/DoctrineDbalAdapter.php b/src/Symfony/Component/Cache/Adapter/DoctrineDbalAdapter.php
index c69c777c993e7..7c5379e417355 100644
--- a/src/Symfony/Component/Cache/Adapter/DoctrineDbalAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/DoctrineDbalAdapter.php
@@ -335,17 +335,17 @@ protected function doSave(array $values, int $lifetime): array|bool
     /**
      * @internal
      */
-    protected function getId(mixed $key): string
+    protected function getId(mixed $key, ?string $namespace = null): string
     {
         if ('pgsql' !== $this->platformName ??= $this->getPlatformName()) {
-            return parent::getId($key);
+            return parent::getId($key, $namespace);
         }
 
         if (str_contains($key, "\0") || str_contains($key, '%') || !preg_match('//u', $key)) {
             $key = rawurlencode($key);
         }
 
-        return parent::getId($key);
+        return parent::getId($key, $namespace);
     }
 
     private function getPlatformName(): string
diff --git a/src/Symfony/Component/Cache/Adapter/NullAdapter.php b/src/Symfony/Component/Cache/Adapter/NullAdapter.php
index d5d2ef6b40d03..35553ea15f89a 100644
--- a/src/Symfony/Component/Cache/Adapter/NullAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/NullAdapter.php
@@ -14,11 +14,12 @@
 use Psr\Cache\CacheItemInterface;
 use Symfony\Component\Cache\CacheItem;
 use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 
 /**
  * @author Titouan Galopin <galopintitouan@gmail.com>
  */
-class NullAdapter implements AdapterInterface, CacheInterface
+class NullAdapter implements AdapterInterface, CacheInterface, NamespacedPoolInterface
 {
     private static \Closure $createCacheItem;
 
@@ -94,6 +95,11 @@ public function delete(string $key): bool
         return $this->deleteItem($key);
     }
 
+    public function withSubNamespace(string $namespace): static
+    {
+        return clone $this;
+    }
+
     private function generateItems(array $keys): \Generator
     {
         $f = self::$createCacheItem;
diff --git a/src/Symfony/Component/Cache/Adapter/PdoAdapter.php b/src/Symfony/Component/Cache/Adapter/PdoAdapter.php
index 525e2c6db6020..7d6cb2dfcb6d1 100644
--- a/src/Symfony/Component/Cache/Adapter/PdoAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/PdoAdapter.php
@@ -348,17 +348,17 @@ protected function doSave(array $values, int $lifetime): array|bool
     /**
      * @internal
      */
-    protected function getId(mixed $key): string
+    protected function getId(mixed $key, ?string $namespace = null): string
     {
         if ('pgsql' !== $this->getDriver()) {
-            return parent::getId($key);
+            return parent::getId($key, $namespace);
         }
 
         if (str_contains($key, "\0") || str_contains($key, '%') || !preg_match('//u', $key)) {
             $key = rawurlencode($key);
         }
 
-        return parent::getId($key);
+        return parent::getId($key, $namespace);
     }
 
     private function getConnection(): \PDO
diff --git a/src/Symfony/Component/Cache/Adapter/ProxyAdapter.php b/src/Symfony/Component/Cache/Adapter/ProxyAdapter.php
index 5621226069bb1..d692dbf3d5c15 100644
--- a/src/Symfony/Component/Cache/Adapter/ProxyAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ProxyAdapter.php
@@ -19,11 +19,12 @@
 use Symfony\Component\Cache\Traits\ContractsTrait;
 use Symfony\Component\Cache\Traits\ProxyTrait;
 use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 
 /**
  * @author Nicolas Grekas <p@tchwork.com>
  */
-class ProxyAdapter implements AdapterInterface, CacheInterface, PruneableInterface, ResettableInterface
+class ProxyAdapter implements AdapterInterface, NamespacedPoolInterface, CacheInterface, PruneableInterface, ResettableInterface
 {
     use ContractsTrait;
     use ProxyTrait;
@@ -38,12 +39,17 @@ class ProxyAdapter implements AdapterInterface, CacheInterface, PruneableInterfa
 
     public function __construct(CacheItemPoolInterface $pool, string $namespace = '', int $defaultLifetime = 0)
     {
-        $this->pool = $pool;
-        $this->poolHash = spl_object_hash($pool);
         if ('' !== $namespace) {
-            \assert('' !== CacheItem::validateKey($namespace));
-            $this->namespace = $namespace;
+            if ($pool instanceof NamespacedPoolInterface) {
+                $pool = $pool->withSubNamespace($namespace);
+                $this->namespace = $namespace = '';
+            } else {
+                \assert('' !== CacheItem::validateKey($namespace));
+                $this->namespace = $namespace;
+            }
         }
+        $this->pool = $pool;
+        $this->poolHash = spl_object_hash($pool);
         $this->namespaceLen = \strlen($namespace);
         $this->defaultLifetime = $defaultLifetime;
         self::$createCacheItem ??= \Closure::bind(
@@ -158,6 +164,20 @@ public function commit(): bool
         return $this->pool->commit();
     }
 
+    public function withSubNamespace(string $namespace): static
+    {
+        $clone = clone $this;
+
+        if ($clone->pool instanceof NamespacedPoolInterface) {
+            $clone->pool = $clone->pool->withSubNamespace($namespace);
+        } else {
+            $clone->namespace .= CacheItem::validateKey($namespace);
+            $clone->namespaceLen = \strlen($clone->namespace);
+        }
+
+        return $clone;
+    }
+
     private function doSave(CacheItemInterface $item, string $method): bool
     {
         if (!$item instanceof CacheItem) {
diff --git a/src/Symfony/Component/Cache/Adapter/RedisTagAwareAdapter.php b/src/Symfony/Component/Cache/Adapter/RedisTagAwareAdapter.php
index a887f29abfb0a..779c4d91f855e 100644
--- a/src/Symfony/Component/Cache/Adapter/RedisTagAwareAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/RedisTagAwareAdapter.php
@@ -159,7 +159,7 @@ protected function doDeleteYieldTags(array $ids): iterable
 
         foreach ($results as $id => $result) {
             if ($result instanceof \RedisException || $result instanceof \Relay\Exception || $result instanceof ErrorInterface) {
-                CacheItem::log($this->logger, 'Failed to delete key "{key}": '.$result->getMessage(), ['key' => substr($id, \strlen($this->namespace)), 'exception' => $result]);
+                CacheItem::log($this->logger, 'Failed to delete key "{key}": '.$result->getMessage(), ['key' => substr($id, \strlen($this->rootNamespace)), 'exception' => $result]);
 
                 continue;
             }
diff --git a/src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php b/src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php
index 53c989047ff63..70927cf4e5b8a 100644
--- a/src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php
@@ -16,9 +16,11 @@
 use Psr\Log\LoggerAwareInterface;
 use Psr\Log\LoggerAwareTrait;
 use Symfony\Component\Cache\CacheItem;
+use Symfony\Component\Cache\Exception\BadMethodCallException;
 use Symfony\Component\Cache\PruneableInterface;
 use Symfony\Component\Cache\ResettableInterface;
 use Symfony\Component\Cache\Traits\ContractsTrait;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 use Symfony\Contracts\Cache\TagAwareCacheInterface;
 
 /**
@@ -33,7 +35,7 @@
  * @author Nicolas Grekas <p@tchwork.com>
  * @author Sergey Belyshkin <sbelyshkin@gmail.com>
  */
-class TagAwareAdapter implements TagAwareAdapterInterface, TagAwareCacheInterface, PruneableInterface, ResettableInterface, LoggerAwareInterface
+class TagAwareAdapter implements TagAwareAdapterInterface, TagAwareCacheInterface, NamespacedPoolInterface, PruneableInterface, ResettableInterface, LoggerAwareInterface
 {
     use ContractsTrait;
     use LoggerAwareTrait;
@@ -277,6 +279,23 @@ public function commit(): bool
         return $ok;
     }
 
+    /**
+     * @throws BadMethodCallException When the item pool is not a NamespacedPoolInterface
+     */
+    public function withSubNamespace(string $namespace): static
+    {
+        if (!$this->pool instanceof NamespacedPoolInterface) {
+            throw new BadMethodCallException(\sprintf('Cannot call "%s::withSubNamespace()": this class doesn\'t implement "%s".', get_debug_type($this->pool), NamespacedPoolInterface::class));
+        }
+
+        $knownTagVersions = &$this->knownTagVersions; // ensures clones share the same array
+        $clone = clone $this;
+        $clone->deferred = [];
+        $clone->pool = $this->pool->withSubNamespace($namespace);
+
+        return $clone;
+    }
+
     public function prune(): bool
     {
         return $this->pool instanceof PruneableInterface && $this->pool->prune();
diff --git a/src/Symfony/Component/Cache/Adapter/TraceableAdapter.php b/src/Symfony/Component/Cache/Adapter/TraceableAdapter.php
index 8fe6cf3764806..43628e4cedbf0 100644
--- a/src/Symfony/Component/Cache/Adapter/TraceableAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/TraceableAdapter.php
@@ -13,9 +13,11 @@
 
 use Psr\Cache\CacheItemInterface;
 use Symfony\Component\Cache\CacheItem;
+use Symfony\Component\Cache\Exception\BadMethodCallException;
 use Symfony\Component\Cache\PruneableInterface;
 use Symfony\Component\Cache\ResettableInterface;
 use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 use Symfony\Contracts\Service\ResetInterface;
 
 /**
@@ -25,8 +27,9 @@
  * @author Tobias Nyholm <tobias.nyholm@gmail.com>
  * @author Nicolas Grekas <p@tchwork.com>
  */
-class TraceableAdapter implements AdapterInterface, CacheInterface, PruneableInterface, ResettableInterface
+class TraceableAdapter implements AdapterInterface, CacheInterface, NamespacedPoolInterface, PruneableInterface, ResettableInterface
 {
+    private string $namespace = '';
     private array $calls = [];
 
     public function __construct(
@@ -34,10 +37,13 @@ public function __construct(
     ) {
     }
 
+    /**
+     * @throws BadMethodCallException When the item pool is not a CacheInterface
+     */
     public function get(string $key, callable $callback, ?float $beta = null, ?array &$metadata = null): mixed
     {
         if (!$this->pool instanceof CacheInterface) {
-            throw new \BadMethodCallException(\sprintf('Cannot call "%s::get()": this class doesn\'t implement "%s".', get_debug_type($this->pool), CacheInterface::class));
+            throw new BadMethodCallException(\sprintf('Cannot call "%s::get()": this class doesn\'t implement "%s".', get_debug_type($this->pool), CacheInterface::class));
         }
 
         $isHit = true;
@@ -225,11 +231,29 @@ public function getPool(): AdapterInterface
         return $this->pool;
     }
 
+    /**
+     * @throws BadMethodCallException When the item pool is not a NamespacedPoolInterface
+     */
+    public function withSubNamespace(string $namespace): static
+    {
+        if (!$this->pool instanceof NamespacedPoolInterface) {
+            throw new BadMethodCallException(\sprintf('Cannot call "%s::withSubNamespace()": this class doesn\'t implement "%s".', get_debug_type($this->pool), NamespacedPoolInterface::class));
+        }
+
+        $calls = &$this->calls; // ensures clones share the same array
+        $clone = clone $this;
+        $clone->namespace .= CacheItem::validateKey($namespace).':';
+        $clone->pool = $this->pool->withSubNamespace($namespace);
+
+        return $clone;
+    }
+
     protected function start(string $name): TraceableAdapterEvent
     {
         $this->calls[] = $event = new TraceableAdapterEvent();
         $event->name = $name;
         $event->start = microtime(true);
+        $event->namespace = $this->namespace;
 
         return $event;
     }
@@ -246,4 +270,5 @@ class TraceableAdapterEvent
     public array|bool $result;
     public int $hits = 0;
     public int $misses = 0;
+    public string $namespace;
 }
diff --git a/src/Symfony/Component/Cache/CHANGELOG.md b/src/Symfony/Component/Cache/CHANGELOG.md
index 59195f03edbfa..d7b18246802dd 100644
--- a/src/Symfony/Component/Cache/CHANGELOG.md
+++ b/src/Symfony/Component/Cache/CHANGELOG.md
@@ -6,6 +6,7 @@ CHANGELOG
 
  * Add support for `\Relay\Cluster` in `RedisAdapter`
  * Add support for `valkey:` / `valkeys:` schemes
+ * Add support for namespace-based invalidation
  * Rename options "redis_cluster" and "redis_sentinel" to "cluster" and "sentinel" respectively
 
 7.2
diff --git a/src/Symfony/Component/Cache/Exception/BadMethodCallException.php b/src/Symfony/Component/Cache/Exception/BadMethodCallException.php
new file mode 100644
index 0000000000000..d81f9d26464a9
--- /dev/null
+++ b/src/Symfony/Component/Cache/Exception/BadMethodCallException.php
@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Cache\Exception;
+
+use Psr\Cache\CacheException as Psr6CacheInterface;
+use Psr\SimpleCache\CacheException as SimpleCacheInterface;
+
+if (interface_exists(SimpleCacheInterface::class)) {
+    class BadMethodCallException extends \BadMethodCallException implements Psr6CacheInterface, SimpleCacheInterface
+    {
+    }
+} else {
+    class BadMethodCallException extends \BadMethodCallException implements Psr6CacheInterface
+    {
+    }
+}
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php b/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
index da430296bcdcf..35eefb501b5a6 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
@@ -18,6 +18,7 @@
 use Symfony\Component\Cache\CacheItem;
 use Symfony\Component\Cache\PruneableInterface;
 use Symfony\Contracts\Cache\CallbackInterface;
+use Symfony\Contracts\Cache\NamespacedPoolInterface;
 
 abstract class AdapterTestCase extends CachePoolTest
 {
@@ -350,6 +351,33 @@ public function testNumericKeysWorkAfterMemoryLeakPrevention()
 
         $this->assertEquals('value-50', $cache->getItem((string) 50)->get());
     }
+
+    public function testNamespaces()
+    {
+        if (isset($this->skippedTests[__FUNCTION__])) {
+            $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
+        }
+
+        $cache = $this->createCachePool(0, __FUNCTION__);
+
+        $this->assertInstanceOf(NamespacedPoolInterface::class, $cache);
+
+        $derived = $cache->withSubNamespace('derived');
+
+        $item = $derived->getItem('foo');
+        $derived->save($item->set('Foo'));
+
+        $this->assertFalse($cache->getItem('foo')->isHit());
+
+        $item = $cache->getItem('bar');
+        $cache->save($item->set('Bar'));
+
+        $this->assertFalse($derived->getItem('bar')->isHit());
+        $this->assertTrue($cache->getItem('bar')->isHit());
+
+        $derived = $cache->withSubNamespace('derived');
+        $this->assertTrue($derived->getItem('foo')->isHit());
+    }
 }
 
 class NotUnserializable
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/PhpArrayAdapterTest.php b/src/Symfony/Component/Cache/Tests/Adapter/PhpArrayAdapterTest.php
index 5bbe4d1d7be13..5bc2bfeb1fedd 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/PhpArrayAdapterTest.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/PhpArrayAdapterTest.php
@@ -57,6 +57,8 @@ class PhpArrayAdapterTest extends AdapterTestCase
 
         'testDefaultLifeTime' => 'PhpArrayAdapter does not allow configuring a default lifetime.',
         'testPrune' => 'PhpArrayAdapter just proxies',
+
+        'testNamespaces' => 'PhpArrayAdapter does not support namespaces.',
     ];
 
     protected static string $file;
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/PhpArrayAdapterWithFallbackTest.php b/src/Symfony/Component/Cache/Tests/Adapter/PhpArrayAdapterWithFallbackTest.php
index d20ffd554f90a..0f92aee451506 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/PhpArrayAdapterWithFallbackTest.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/PhpArrayAdapterWithFallbackTest.php
@@ -28,6 +28,8 @@ class PhpArrayAdapterWithFallbackTest extends AdapterTestCase
         'testDeleteItemInvalidKeys' => 'PhpArrayAdapter does not throw exceptions on invalid key.',
         'testDeleteItemsInvalidKeys' => 'PhpArrayAdapter does not throw exceptions on invalid key.',
         'testPrune' => 'PhpArrayAdapter just proxies',
+
+        'testNamespaces' => 'PhpArrayAdapter does not support namespaces.',
     ];
 
     protected static string $file;
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/TagAwareTestTrait.php b/src/Symfony/Component/Cache/Tests/Adapter/TagAwareTestTrait.php
index 8ec1297ea24e4..9894ba00982db 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/TagAwareTestTrait.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/TagAwareTestTrait.php
@@ -183,4 +183,27 @@ public function testRefreshAfterExpires()
         $cacheItem = $pool->getItem('test');
         $this->assertTrue($cacheItem->isHit());
     }
+
+    public function testNamespacesAndTags()
+    {
+        $pool = $this->createCachePool();
+        $pool->clear();
+
+        $item = $pool->getItem('foo');
+        $item->tag('baz');
+        $pool->save($item);
+
+        $derived = $pool->withSubNamespace('derived');
+        $item = $derived->getItem('bar');
+        $item->tag('baz');
+        $derived->save($item);
+
+        $this->assertTrue($pool->getItem('foo')->isHit());
+        $this->assertTrue($derived->getItem('bar')->isHit());
+
+        $pool->invalidateTags(['baz']);
+
+        $this->assertFalse($pool->getItem('foo')->isHit());
+        $this->assertFalse($derived->getItem('bar')->isHit());
+    }
 }
diff --git a/src/Symfony/Component/Cache/Tests/Psr16CacheProxyTest.php b/src/Symfony/Component/Cache/Tests/Psr16CacheProxyTest.php
index c3d2d8d59f444..fa771cf92207f 100644
--- a/src/Symfony/Component/Cache/Tests/Psr16CacheProxyTest.php
+++ b/src/Symfony/Component/Cache/Tests/Psr16CacheProxyTest.php
@@ -45,12 +45,12 @@ public function createSimpleCache(int $defaultLifetime = 0): CacheInterface
     public function testProxy()
     {
         $pool = new ArrayAdapter();
-        $cache = new Psr16Cache(new ProxyAdapter($pool, 'my-namespace.'));
+        $cache = new Psr16Cache(new ProxyAdapter($pool, 'my-namespace'));
 
         $this->assertNull($cache->get('some-key'));
         $this->assertTrue($cache->set('some-other-key', 'value'));
 
-        $item = $pool->getItem('my-namespace.some-other-key', 'value');
+        $item = $pool->withSubNamespace('my-namespace')->getItem('some-other-key', 'value');
         $this->assertTrue($item->isHit());
         $this->assertSame('value', $item->get());
     }
diff --git a/src/Symfony/Component/Cache/Traits/AbstractAdapterTrait.php b/src/Symfony/Component/Cache/Traits/AbstractAdapterTrait.php
index 6a716743ffc94..ac8dc97a23c34 100644
--- a/src/Symfony/Component/Cache/Traits/AbstractAdapterTrait.php
+++ b/src/Symfony/Component/Cache/Traits/AbstractAdapterTrait.php
@@ -35,6 +35,7 @@ trait AbstractAdapterTrait
      */
     private static \Closure $mergeByLifetime;
 
+    private readonly string $rootNamespace;
     private string $namespace = '';
     private int $defaultLifetime;
     private string $namespaceVersion = '';
@@ -106,15 +107,16 @@ public function clear(string $prefix = ''): bool
     {
         $this->deferred = [];
         if ($cleared = $this->versioningIsEnabled) {
+            $rootNamespace = $this->rootNamespace ??= $this->namespace;
             if ('' === $namespaceVersionToClear = $this->namespaceVersion) {
-                foreach ($this->doFetch([static::NS_SEPARATOR.$this->namespace]) as $v) {
+                foreach ($this->doFetch([static::NS_SEPARATOR.$rootNamespace]) as $v) {
                     $namespaceVersionToClear = $v;
                 }
             }
-            $namespaceToClear = $this->namespace.$namespaceVersionToClear;
+            $namespaceToClear = $rootNamespace.$namespaceVersionToClear;
             $namespaceVersion = self::formatNamespaceVersion(mt_rand());
             try {
-                $e = $this->doSave([static::NS_SEPARATOR.$this->namespace => $namespaceVersion], 0);
+                $e = $this->doSave([static::NS_SEPARATOR.$rootNamespace => $namespaceVersion], 0);
             } catch (\Exception $e) {
             }
             if (true !== $e && [] !== $e) {
@@ -247,6 +249,16 @@ public function saveDeferred(CacheItemInterface $item): bool
         return true;
     }
 
+    public function withSubNamespace(string $namespace): static
+    {
+        $this->rootNamespace ??= $this->namespace;
+
+        $clone = clone $this;
+        $clone->namespace .= CacheItem::validateKey($namespace).static::NS_SEPARATOR;
+
+        return $clone;
+    }
+
     /**
      * Enables/disables versioning of items.
      *
@@ -318,19 +330,24 @@ private function generateItems(iterable $items, array &$keys): \Generator
     /**
      * @internal
      */
-    protected function getId(mixed $key): string
+    protected function getId(mixed $key, ?string $namespace = null): string
     {
-        if ($this->versioningIsEnabled && '' === $this->namespaceVersion) {
+        $namespace ??= $this->namespace;
+
+        if ('' !== $this->namespaceVersion) {
+            $namespace .= $this->namespaceVersion;
+        } elseif ($this->versioningIsEnabled) {
+            $rootNamespace = $this->rootNamespace ??= $this->namespace;
             $this->ids = [];
             $this->namespaceVersion = '1'.static::NS_SEPARATOR;
             try {
-                foreach ($this->doFetch([static::NS_SEPARATOR.$this->namespace]) as $v) {
+                foreach ($this->doFetch([static::NS_SEPARATOR.$rootNamespace]) as $v) {
                     $this->namespaceVersion = $v;
                 }
                 $e = true;
                 if ('1'.static::NS_SEPARATOR === $this->namespaceVersion) {
                     $this->namespaceVersion = self::formatNamespaceVersion(time());
-                    $e = $this->doSave([static::NS_SEPARATOR.$this->namespace => $this->namespaceVersion], 0);
+                    $e = $this->doSave([static::NS_SEPARATOR.$rootNamespace => $this->namespaceVersion], 0);
                 }
             } catch (\Exception $e) {
             }
@@ -338,25 +355,34 @@ protected function getId(mixed $key): string
                 $message = 'Failed to save the new namespace'.($e instanceof \Exception ? ': '.$e->getMessage() : '.');
                 CacheItem::log($this->logger, $message, ['exception' => $e instanceof \Exception ? $e : null, 'cache-adapter' => get_debug_type($this)]);
             }
+
+            $namespace .= $this->namespaceVersion;
         }
 
         if (\is_string($key) && isset($this->ids[$key])) {
-            return $this->namespace.$this->namespaceVersion.$this->ids[$key];
-        }
-        \assert('' !== CacheItem::validateKey($key));
-        $this->ids[$key] = $key;
+            $id = $this->ids[$key];
+        } else {
+            \assert('' !== CacheItem::validateKey($key));
+            $this->ids[$key] = $key;
 
-        if (\count($this->ids) > 1000) {
-            $this->ids = \array_slice($this->ids, 500, null, true); // stop memory leak if there are many keys
-        }
+            if (\count($this->ids) > 1000) {
+                $this->ids = \array_slice($this->ids, 500, null, true); // stop memory leak if there are many keys
+            }
+
+            if (null === $this->maxIdLength) {
+                return $namespace.$key;
+            }
+            if (\strlen($id = $namespace.$key) <= $this->maxIdLength) {
+                return $id;
+            }
 
-        if (null === $this->maxIdLength) {
-            return $this->namespace.$this->namespaceVersion.$key;
-        }
-        if (\strlen($id = $this->namespace.$this->namespaceVersion.$key) > $this->maxIdLength) {
             // Use xxh128 to favor speed over security, which is not an issue here
             $this->ids[$key] = $id = substr_replace(base64_encode(hash('xxh128', $key, true)), static::NS_SEPARATOR, -(\strlen($this->namespaceVersion) + 2));
-            $id = $this->namespace.$this->namespaceVersion.$id;
+        }
+        $id = $namespace.$id;
+
+        if (null !== $this->maxIdLength && \strlen($id) > $this->maxIdLength) {
+            return base64_encode(hash('xxh128', $id, true));
         }
 
         return $id;
diff --git a/src/Symfony/Component/Cache/composer.json b/src/Symfony/Component/Cache/composer.json
index bdb461be8c9e2..c89d667288286 100644
--- a/src/Symfony/Component/Cache/composer.json
+++ b/src/Symfony/Component/Cache/composer.json
@@ -24,7 +24,7 @@
         "php": ">=8.2",
         "psr/cache": "^2.0|^3.0",
         "psr/log": "^1.1|^2|^3",
-        "symfony/cache-contracts": "^2.5|^3",
+        "symfony/cache-contracts": "^3.6",
         "symfony/deprecation-contracts": "^2.5|^3.0",
         "symfony/service-contracts": "^2.5|^3",
         "symfony/var-exporter": "^6.4|^7.0"
diff --git a/src/Symfony/Contracts/CHANGELOG.md b/src/Symfony/Contracts/CHANGELOG.md
index ffbd4d2ef81d5..dc9ba968168bc 100644
--- a/src/Symfony/Contracts/CHANGELOG.md
+++ b/src/Symfony/Contracts/CHANGELOG.md
@@ -5,6 +5,7 @@ CHANGELOG
 ---
 
  * Make `HttpClientTestCase` and `TranslatorTest` compatible with PHPUnit 10+
+ * Add `NamespacedPoolInterface` to support namespace-based invalidation
 
 3.5
 ---
diff --git a/src/Symfony/Contracts/Cache/NamespacedPoolInterface.php b/src/Symfony/Contracts/Cache/NamespacedPoolInterface.php
new file mode 100644
index 0000000000000..cd67bc09bc882
--- /dev/null
+++ b/src/Symfony/Contracts/Cache/NamespacedPoolInterface.php
@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Contracts\Cache;
+
+use Psr\Cache\InvalidArgumentException;
+
+/**
+ * Enables namespace-based invalidation by prefixing keys with backend-native namespace separators.
+ *
+ * Note that calling `withSubNamespace()` MUST NOT mutate the pool, but return a new instance instead.
+ *
+ * When tags are used, they MUST ignore sub-namespaces.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+interface NamespacedPoolInterface
+{
+    /**
+     * @throws InvalidArgumentException If the namespace contains characters found in ItemInterface's RESERVED_CHARACTERS
+     */
+    public function withSubNamespace(string $namespace): static;
+}