diff --git a/CacheInterface.php b/CacheInterface.php
index 70cb0d5..3e4aaf6 100644
--- a/CacheInterface.php
+++ b/CacheInterface.php
@@ -29,20 +29,22 @@ interface CacheInterface
      * requested key, that could be used e.g. for expiration control. It could also
      * be an ItemInterface instance when its additional features are needed.
      *
-     * @param string                     $key       The key of the item to retrieve from the cache
-     * @param callable|CallbackInterface $callback  Should return the computed value for the given key/item
-     * @param float|null                 $beta      A float that, as it grows, controls the likeliness of triggering
-     *                                              early expiration. 0 disables it, INF forces immediate expiration.
-     *                                              The default (or providing null) is implementation dependent but should
-     *                                              typically be 1.0, which should provide optimal stampede protection.
-     *                                              See https://en.wikipedia.org/wiki/Cache_stampede#Probabilistic_early_expiration
-     * @param array                      &$metadata The metadata of the cached item {@see ItemInterface::getMetadata()}
+     * @template T
      *
-     * @return mixed
+     * @param string $key The key of the item to retrieve from the cache
+     * @param (callable(CacheItemInterface,bool):T)|(callable(ItemInterface,bool):T)|CallbackInterface<T> $callback
+     * @param float|null $beta      A float that, as it grows, controls the likeliness of triggering
+     *                              early expiration. 0 disables it, INF forces immediate expiration.
+     *                              The default (or providing null) is implementation dependent but should
+     *                              typically be 1.0, which should provide optimal stampede protection.
+     *                              See https://en.wikipedia.org/wiki/Cache_stampede#Probabilistic_early_expiration
+     * @param array      &$metadata The metadata of the cached item {@see ItemInterface::getMetadata()}
+     *
+     * @return T
      *
      * @throws InvalidArgumentException When $key is not valid or when $beta is negative
      */
-    public function get(string $key, callable $callback, ?float $beta = null, ?array &$metadata = null);
+    public function get(string $key, callable $callback, ?float $beta = null, ?array &$metadata = null): mixed;
 
     /**
      * Removes an item from the pool.
diff --git a/CacheTrait.php b/CacheTrait.php
index b9feafb..4c5449b 100644
--- a/CacheTrait.php
+++ b/CacheTrait.php
@@ -25,28 +25,20 @@ class_exists(InvalidArgumentException::class);
  */
 trait CacheTrait
 {
-    /**
-     * {@inheritdoc}
-     *
-     * @return mixed
-     */
-    public function get(string $key, callable $callback, ?float $beta = null, ?array &$metadata = null)
+    public function get(string $key, callable $callback, ?float $beta = null, ?array &$metadata = null): mixed
     {
         return $this->doGet($this, $key, $callback, $beta, $metadata);
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function delete(string $key): bool
     {
         return $this->deleteItem($key);
     }
 
-    private function doGet(CacheItemPoolInterface $pool, string $key, callable $callback, ?float $beta, ?array &$metadata = null, ?LoggerInterface $logger = null)
+    private function doGet(CacheItemPoolInterface $pool, string $key, callable $callback, ?float $beta, ?array &$metadata = null, ?LoggerInterface $logger = null): mixed
     {
-        if (0 > $beta = $beta ?? 1.0) {
-            throw new class(sprintf('Argument "$beta" provided to "%s::get()" must be a positive number, %f given.', static::class, $beta)) extends \InvalidArgumentException implements InvalidArgumentException { };
+        if (0 > $beta ??= 1.0) {
+            throw new class(\sprintf('Argument "$beta" provided to "%s::get()" must be a positive number, %f given.', static::class, $beta)) extends \InvalidArgumentException implements InvalidArgumentException {};
         }
 
         $item = $pool->getItem($key);
@@ -60,9 +52,9 @@ private function doGet(CacheItemPoolInterface $pool, string $key, callable $call
             if ($recompute = $ctime && $expiry && $expiry <= ($now = microtime(true)) - $ctime / 1000 * $beta * log(random_int(1, \PHP_INT_MAX) / \PHP_INT_MAX)) {
                 // force applying defaultLifetime to expiry
                 $item->expiresAt(null);
-                $logger && $logger->info('Item "{key}" elected for early recomputation {delta}s before its expiration', [
+                $logger?->info('Item "{key}" elected for early recomputation {delta}s before its expiration', [
                     'key' => $key,
-                    'delta' => sprintf('%.1f', $expiry - $now),
+                    'delta' => \sprintf('%.1f', $expiry - $now),
                 ]);
             }
         }
diff --git a/CallbackInterface.php b/CallbackInterface.php
index 7dae2aa..15941e9 100644
--- a/CallbackInterface.php
+++ b/CallbackInterface.php
@@ -17,6 +17,8 @@
  * Computes and returns the cached value of an item.
  *
  * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @template T
  */
 interface CallbackInterface
 {
@@ -24,7 +26,7 @@ interface CallbackInterface
      * @param CacheItemInterface|ItemInterface $item  The item to compute the value for
      * @param bool                             &$save Should be set to false when the value should not be saved in the pool
      *
-     * @return mixed The computed value for the passed item
+     * @return T The computed value for the passed item
      */
-    public function __invoke(CacheItemInterface $item, bool &$save);
+    public function __invoke(CacheItemInterface $item, bool &$save): mixed;
 }
diff --git a/ItemInterface.php b/ItemInterface.php
index 10c0488..8c4c512 100644
--- a/ItemInterface.php
+++ b/ItemInterface.php
@@ -54,7 +54,7 @@ interface ItemInterface extends CacheItemInterface
      * @throws InvalidArgumentException When $tag is not valid
      * @throws CacheException           When the item comes from a pool that is not tag-aware
      */
-    public function tag($tags): self;
+    public function tag(string|iterable $tags): static;
 
     /**
      * Returns a list of metadata info that were saved alongside with the cached value.
diff --git a/NamespacedPoolInterface.php b/NamespacedPoolInterface.php
new file mode 100644
index 0000000..cd67bc0
--- /dev/null
+++ b/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;
+}
diff --git a/README.md b/README.md
index 7085a69..ffe0833 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@ Symfony Cache Contracts
 
 A set of abstractions extracted out of the Symfony components.
 
-Can be used to build on semantics that the Symfony components proved useful - and
+Can be used to build on semantics that the Symfony components proved useful and
 that already have battle tested implementations.
 
 See https://github.com/symfony/contracts/blob/main/README.md for more information.
diff --git a/TagAwareCacheInterface.php b/TagAwareCacheInterface.php
index 7c4cf11..8e0b6be 100644
--- a/TagAwareCacheInterface.php
+++ b/TagAwareCacheInterface.php
@@ -34,5 +34,5 @@ interface TagAwareCacheInterface extends CacheInterface
      *
      * @throws InvalidArgumentException When $tags is not valid
      */
-    public function invalidateTags(array $tags);
+    public function invalidateTags(array $tags): bool;
 }
diff --git a/composer.json b/composer.json
index 9f45e17..b713c29 100644
--- a/composer.json
+++ b/composer.json
@@ -16,11 +16,8 @@
         }
     ],
     "require": {
-        "php": ">=7.2.5",
-        "psr/cache": "^1.0|^2.0|^3.0"
-    },
-    "suggest": {
-        "symfony/cache-implementation": ""
+        "php": ">=8.1",
+        "psr/cache": "^3.0"
     },
     "autoload": {
         "psr-4": { "Symfony\\Contracts\\Cache\\": "" }
@@ -28,7 +25,7 @@
     "minimum-stability": "dev",
     "extra": {
         "branch-alias": {
-            "dev-main": "2.5-dev"
+            "dev-main": "3.6-dev"
         },
         "thanks": {
             "name": "symfony/contracts",

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