diff --git a/README.md b/README.md
index 4d880e9..cb67f5b 100644
--- a/README.md
+++ b/README.md
@@ -245,6 +245,19 @@ Runwire keeps ownership of listeners, workers, supervisors, and event loops. `Ru
 
 Concurrent persistent Runwire requests receive request-owned memoizer state. If a concurrent runtime is bound without a shared request scope, memoization helpers bypass the process-global cache rather than risk cross-request leakage. See `docs/runwire.rst` and the executable `examples/runwire-invalidation-worker.php`.
 
+A framework can also pass its runtime for one request/task without a global bind:
+
+```php
+RunwireIntegration::share($request, $scope, function () {
+    // Normal cache and memoization operations use this task's context.
+}, $runtime);
+```
+
+The fourth argument is optional. `runtime()` and capability checks reflect the
+current task while the callback runs; nested sharing and exceptions restore the
+previous context. This borrowing does not bind, release or replace the host's
+global runtime. Concurrent requests receive separate memoizers.
+
 ## Atomic counters and memoization
 
 `AtomicCounters` uses an `AtomicCounterStoreInterface`; Redis/Valkey is the distributed implementation. Counters are never emulated with cache `get()` plus `set()`. They live in a dedicated `cachelayer:counter:<namespace>:` keyspace, so ordinary cache `clear()` does not reset them, and the Lua update returns an exact decimal string before PHP range validation. Atomic counters are separate from `Cache::atomic()`: counters mutate numeric state, while the cache capability provides conditional claim/replace/consume primitives for encoded cache records.
diff --git a/src/Cache/Adapter/AdapterValueNormalizer.php b/src/Cache/Adapter/AdapterValueNormalizer.php
index 35dd4ac..3b5a2a2 100644
--- a/src/Cache/Adapter/AdapterValueNormalizer.php
+++ b/src/Cache/Adapter/AdapterValueNormalizer.php
@@ -72,6 +72,15 @@ public static function normalizeAssoc(array $value): array
         return $out;
     }
 
+    public static function pdoPayload(mixed $value): ?string
+    {
+        if (is_resource($value)) {
+            $value = stream_get_contents($value);
+        }
+
+        return is_string($value) ? $value : null;
+    }
+
     /**
      * @phpstan-return array<string, mixed>|null
      * @param object $value The value argument.
diff --git a/src/Cache/Adapter/CachePayloadCodec.php b/src/Cache/Adapter/CachePayloadCodec.php
index 3588679..5fac04b 100644
--- a/src/Cache/Adapter/CachePayloadCodec.php
+++ b/src/Cache/Adapter/CachePayloadCodec.php
@@ -128,6 +128,12 @@ public function encode(
         return $encoded;
     }
 
+    /** @phpstan-assert-if-true =string $value */
+    private static function isGeneration(mixed $value): bool
+    {
+        return is_string($value) && strlen($value) === 32 && ctype_xdigit($value);
+    }
+
     private function assertNativeValueSupported(mixed $value): void
     {
         if ($value instanceof Closure) {
@@ -281,10 +287,7 @@ private function normalizeRecord(mixed $decoded): ?CacheRecord
             return null;
         }
         $namespaceGeneration = $decoded['namespace'] ?? null;
-        if ($namespaceGeneration !== null
-            && (!is_string($namespaceGeneration)
-                || strlen($namespaceGeneration) !== 32
-                || !ctype_xdigit($namespaceGeneration))) {
+        if ($namespaceGeneration !== null && !self::isGeneration($namespaceGeneration)) {
             return null;
         }
 
@@ -294,9 +297,7 @@ private function normalizeRecord(mixed $decoded): ?CacheRecord
         }
 
         foreach ($tags as $generation) {
-            if (!is_string($generation)
-                || strlen($generation) !== 32
-                || !ctype_xdigit($generation)) {
+            if (!self::isGeneration($generation)) {
                 return null;
             }
         }
diff --git a/src/Cache/Adapter/MemcachedCacheAdapter.php b/src/Cache/Adapter/MemcachedCacheAdapter.php
index adf8292..175c902 100644
--- a/src/Cache/Adapter/MemcachedCacheAdapter.php
+++ b/src/Cache/Adapter/MemcachedCacheAdapter.php
@@ -259,17 +259,15 @@ public function multiFetch(array $keys): array
         foreach ($keys as $key) {
             $mapped = $this->mapData($key);
             $blob = $stored[$mapped] ?? null;
-            if ($blob === self::ATOMIC_TOMBSTONE) {
+            if (!is_string($blob) || $blob === self::ATOMIC_TOMBSTONE) {
                 $items[$key] = $this->genericMiss($key);
 
                 continue;
             }
-            $record = is_string($blob) ? $this->decodeRecordFromBlob($blob, $key) : null;
+            $record = $this->decodeRecordFromBlob($blob, $key);
             if ($record === null || $record->namespaceGeneration !== $generation) {
                 $items[$key] = $this->genericMiss($key);
-                if (is_string($blob)) {
-                    $stale[] = [$mapped, $blob];
-                }
+                $stale[] = [$mapped, $blob];
 
                 continue;
             }
diff --git a/src/Cache/Adapter/MongoDbCacheAdapter.php b/src/Cache/Adapter/MongoDbCacheAdapter.php
index e755905..193f353 100644
--- a/src/Cache/Adapter/MongoDbCacheAdapter.php
+++ b/src/Cache/Adapter/MongoDbCacheAdapter.php
@@ -195,26 +195,7 @@ public function getTagGenerations(array $tags): array
                 continue;
             }
 
-            $candidate = self::newGeneration();
-
-            try {
-                $this->collection->updateOne(
-                    ['_id' => $this->mapTag($tag)],
-                    [
-                        '$setOnInsert' => [
-                            'ns' => $this->ns,
-                            'kind' => 'metadata',
-                            'tag' => $tag,
-                            'generation' => $candidate,
-                        ],
-                    ],
-                    ['upsert' => true],
-                );
-            } catch (Throwable $failure) {
-                if (!$this->isDuplicateKeyFailure($failure)) {
-                    throw $failure;
-                }
-            }
+            $this->initializeTagGeneration($tag);
         }
 
         $actual = $this->readTagGenerations($tags);
@@ -247,9 +228,10 @@ public function multiFetch(array $keys): array
         $byId = [];
         foreach ($documents as $document) {
             $row = AdapterValueNormalizer::fromJsonOrArrayLike($document);
-            if (is_array($row) && is_string($row['_id'] ?? null)) {
-                $byId[$row['_id']] = $row;
+            if (!is_string($row['_id'] ?? null)) {
+                continue;
             }
+            $byId[$row['_id']] = $row;
         }
 
         $items = [];
@@ -282,8 +264,8 @@ public function readTagGenerations(array $tags): array
         $generations = [];
         foreach ($documents as $document) {
             $row = AdapterValueNormalizer::fromJsonOrArrayLike($document);
-            $tag = is_array($row) ? ($row['tag'] ?? null) : null;
-            $generation = is_array($row) ? self::normalizeGeneration($row['generation'] ?? null) : null;
+            $tag = $row['tag'] ?? null;
+            $generation = self::normalizeGeneration($row['generation'] ?? null);
             if (is_string($tag) && $generation !== null) {
                 $generations[$tag] = $generation;
             }
@@ -406,13 +388,12 @@ private function binaryString(mixed $value): ?string
         if (is_string($value)) {
             return $value;
         }
-        if (is_object($value) && is_callable([$value, 'getData'])) {
-            $data = $value->getData();
-
-            return is_string($data) ? $data : null;
+        if (!is_object($value) || !is_callable([$value, 'getData'])) {
+            return null;
         }
+        $data = $value->getData();
 
-        return null;
+        return is_string($data) ? $data : null;
     }
 
     private function binaryValue(string $value): mixed
@@ -424,6 +405,30 @@ private function binaryValue(string $value): mixed
         return $value;
     }
 
+    private function initializeTagGeneration(string $tag): void
+    {
+        $candidate = self::newGeneration();
+
+        try {
+            $this->collection->updateOne(
+                ['_id' => $this->mapTag($tag)],
+                [
+                    '$setOnInsert' => [
+                        'ns' => $this->ns,
+                        'kind' => 'metadata',
+                        'tag' => $tag,
+                        'generation' => $candidate,
+                    ],
+                ],
+                ['upsert' => true],
+            );
+        } catch (Throwable $failure) {
+            if (!$this->isDuplicateKeyFailure($failure)) {
+                throw $failure;
+            }
+        }
+    }
+
     private function isDuplicateKeyFailure(Throwable $failure): bool
     {
         return in_array(AdapterValueNormalizer::intOrZero($failure->getCode()), [11000, 11001, 12582], true)
diff --git a/src/Cache/Adapter/PdoCacheAdapter.php b/src/Cache/Adapter/PdoCacheAdapter.php
index 63cb1c2..6c13d4f 100644
--- a/src/Cache/Adapter/PdoCacheAdapter.php
+++ b/src/Cache/Adapter/PdoCacheAdapter.php
@@ -318,21 +318,8 @@ private function fetchRows(string $kind, array $keys): array
                 . "WHERE namespace = ? AND kind = ? AND cache_key IN ({$marks})",
             );
             $statement->execute([$this->namespace, $kind, ...$chunk]);
-            foreach ($statement->fetchAll(PDO::FETCH_ASSOC) as $row) {
-                if (!is_array($row) || !is_string($row['cache_key'] ?? null)) {
-                    continue;
-                }
-                $payload = $row['payload'] ?? null;
-                if (is_resource($payload)) {
-                    $payload = stream_get_contents($payload);
-                }
-                if (!is_string($payload)) {
-                    continue;
-                }
-                $rows[$row['cache_key']] = [
-                    'payload' => $payload,
-                    'expires' => is_numeric($row['expires'] ?? null) ? (int) $row['expires'] : null,
-                ];
+            foreach ($this->normalizeRows($statement->fetchAll(PDO::FETCH_ASSOC)) as $key => $row) {
+                $rows[$key] = $row;
             }
         }
 
@@ -351,6 +338,30 @@ private function hydrate(string $key, array $row): ?CacheItem
         return $record === null ? null : $this->genericItemFromRecord($key, $record);
     }
 
+    /**
+     * @param array<mixed> $records
+     * @return array<string, array{payload:string, expires:int|null}>
+     */
+    private function normalizeRows(array $records): array
+    {
+        $rows = [];
+        foreach ($records as $row) {
+            if (!is_array($row) || !is_string($row['cache_key'] ?? null)) {
+                continue;
+            }
+            $payload = AdapterValueNormalizer::pdoPayload($row['payload'] ?? null);
+            if (!is_string($payload)) {
+                continue;
+            }
+            $rows[$row['cache_key']] = [
+                'payload' => $payload,
+                'expires' => is_numeric($row['expires'] ?? null) ? (int) $row['expires'] : null,
+            ];
+        }
+
+        return $rows;
+    }
+
     /** @param list<array{0:string, 1:string, 2:string, 3:int|null}> $rows */
     private function upsertChunk(array $rows): bool
     {
diff --git a/src/Cache/Adapter/PdoCacheSchema.php b/src/Cache/Adapter/PdoCacheSchema.php
index 9122ac7..90bdc21 100644
--- a/src/Cache/Adapter/PdoCacheSchema.php
+++ b/src/Cache/Adapter/PdoCacheSchema.php
@@ -41,6 +41,21 @@ public static function install(PDO $pdo, string $table = 'cachelayer_entries'):
             self::hardenMysqlIdentityColumns($pdo, $table);
         }
 
+        self::installExpiryIndex($pdo, $table, $driver);
+    }
+
+    private static function hardenMysqlIdentityColumns(PDO $pdo, string $table): void
+    {
+        $pdo->exec(
+            "ALTER TABLE {$table} "
+            . 'MODIFY namespace VARCHAR(191) CHARACTER SET ascii COLLATE ascii_bin NOT NULL, '
+            . 'MODIFY kind VARCHAR(191) CHARACTER SET ascii COLLATE ascii_bin NOT NULL, '
+            . 'MODIFY cache_key VARCHAR(191) CHARACTER SET ascii COLLATE ascii_bin NOT NULL',
+        );
+    }
+
+    private static function installExpiryIndex(PDO $pdo, string $table, string $driver): void
+    {
         $index = $table . '_expires_idx';
 
         if (in_array($driver, ['mysql', 'mariadb'], true)) {
@@ -59,16 +74,6 @@ public static function install(PDO $pdo, string $table = 'cachelayer_entries'):
         $pdo->exec("CREATE INDEX IF NOT EXISTS {$index} ON {$table}(namespace, kind, expires)");
     }
 
-    private static function hardenMysqlIdentityColumns(PDO $pdo, string $table): void
-    {
-        $pdo->exec(
-            "ALTER TABLE {$table} "
-            . 'MODIFY namespace VARCHAR(191) CHARACTER SET ascii COLLATE ascii_bin NOT NULL, '
-            . 'MODIFY kind VARCHAR(191) CHARACTER SET ascii COLLATE ascii_bin NOT NULL, '
-            . 'MODIFY cache_key VARCHAR(191) CHARACTER SET ascii COLLATE ascii_bin NOT NULL',
-        );
-    }
-
     private static function mysqlIdentityColumnsAreBinary(PDO $pdo, string $table): bool
     {
         $statement = $pdo->prepare(
diff --git a/src/Cache/Adapter/PdoTagGenerationStore.php b/src/Cache/Adapter/PdoTagGenerationStore.php
index eda8f7b..f0f7e2e 100644
--- a/src/Cache/Adapter/PdoTagGenerationStore.php
+++ b/src/Cache/Adapter/PdoTagGenerationStore.php
@@ -83,10 +83,7 @@ private static function fetch(PDO $pdo, string $table, string $namespace, array
                 if (!is_array($row) || !is_string($row['cache_key'] ?? null)) {
                     continue;
                 }
-                $payload = $row['payload'] ?? null;
-                if (is_resource($payload)) {
-                    $payload = stream_get_contents($payload);
-                }
+                $payload = AdapterValueNormalizer::pdoPayload($row['payload'] ?? null);
                 if (is_string($payload)) {
                     $stored[$row['cache_key']] = $payload;
                 }
diff --git a/src/Cache/Adapter/RedisCacheAdapter.php b/src/Cache/Adapter/RedisCacheAdapter.php
index d452b4c..aa16235 100644
--- a/src/Cache/Adapter/RedisCacheAdapter.php
+++ b/src/Cache/Adapter/RedisCacheAdapter.php
@@ -296,21 +296,19 @@ public function multiFetch(array $keys): array
         $stale = [];
         foreach ($keys as $idx => $k) {
             $v = $rawVals[$idx] ?? null;
-            if ($v !== null && $v !== false) {
-                if (!is_string($v)) {
-                    $items[$k] = new CacheItem($this, $k);
+            if (!is_string($v)) {
+                $items[$k] = new CacheItem($this, $k);
 
-                    continue;
-                }
+                continue;
+            }
 
-                $record = $this->decodeRecordFromBlob($v, $k);
-                if ($record !== null) {
-                    $items[$k] = $this->genericItemFromRecord($k, $record);
+            $record = $this->decodeRecordFromBlob($v, $k);
+            if ($record !== null) {
+                $items[$k] = $this->genericItemFromRecord($k, $record);
 
-                    continue;
-                }
-                $stale[] = [$this->map($k), $v];
+                continue;
             }
+            $stale[] = [$this->map($k), $v];
             $items[$k] = new CacheItem($this, $k);
         }
 
diff --git a/src/Cache/Adapter/SharedMemoryCacheAdapter.php b/src/Cache/Adapter/SharedMemoryCacheAdapter.php
index 4a0d028..343c9af 100644
--- a/src/Cache/Adapter/SharedMemoryCacheAdapter.php
+++ b/src/Cache/Adapter/SharedMemoryCacheAdapter.php
@@ -89,24 +89,7 @@ public function atomicGetAndDelete(string $key): CacheItemInterface
 
         $mapped = $this->map($key);
 
-        return $this->withExclusiveLock(function () use ($key, $mapped): CacheItemInterface {
-            $store = $this->loadStore();
-            $blob = $store[$mapped] ?? null;
-            if (!is_string($blob)) {
-                return $this->genericMiss($key);
-            }
-
-            $record = $this->decodeRecordFromBlob($blob, $key);
-            unset($store[$mapped]);
-            if (!$this->store($store)) {
-                throw new RuntimeException('Unable to persist shared-memory atomic consume.');
-            }
-            if (!$record instanceof CacheRecord || !$this->recordTagsAreCurrent($record, $store)) {
-                return $this->genericMiss($key);
-            }
-
-            return $this->genericItemFromRecord($key, $record);
-        });
+        return $this->withExclusiveLock(fn(): CacheItemInterface => $this->consumeRecord($key, $mapped));
     }
 
     public function atomicSetIfAbsent(CacheItemInterface $item): bool
@@ -173,14 +156,7 @@ public function deleteItems(array $keys): bool
             $mappedKeys[] = $this->map($key);
         }
 
-        return $this->withExclusiveLock(function () use ($mappedKeys): bool {
-            $store = $this->loadStore();
-            foreach ($mappedKeys as $mapped) {
-                unset($store[$mapped]);
-            }
-
-            return $this->store($store);
-        });
+        return $this->withExclusiveLock(fn(): bool => $this->updateStore([], $mappedKeys));
     }
 
     public function getItem(string $key): CacheItem
@@ -208,26 +184,7 @@ function () use ($mapped): ?string {
     #[\Override]
     public function getTagGenerations(array $tags): array
     {
-        return $this->withExclusiveLock(function () use ($tags): array {
-            $store = $this->loadStore();
-            $generations = [];
-            $changed = false;
-            foreach ($tags as $tag) {
-                $mapped = $this->mapTag($tag);
-                $generation = self::normalizeGeneration($store[$mapped] ?? null);
-                if ($generation === null) {
-                    $generation = self::newGeneration();
-                    $store[$mapped] = $generation;
-                    $changed = true;
-                }
-                $generations[$tag] = $generation;
-            }
-            if ($changed && !$this->store($store)) {
-                throw new RuntimeException('Unable to initialize shared-memory tag generations.');
-            }
-
-            return $generations;
-        });
+        return $this->withExclusiveLock(fn(): array => $this->initializeTagGenerations($tags));
     }
 
     public function hasItem(string $key): bool
@@ -241,20 +198,7 @@ public function hasItem(string $key): bool
      */
     public function multiFetch(array $keys): array
     {
-        return $this->withSharedLock(function () use ($keys): array {
-            $store = $this->loadStore();
-            $items = [];
-            foreach ($keys as $key) {
-                $mapped = $this->map($key);
-                $blob = $store[$mapped] ?? null;
-                $record = is_string($blob) ? $this->decodeRecordFromBlob($blob, $key) : null;
-                $items[$key] = $record === null
-                    ? $this->genericMiss($key)
-                    : $this->genericItemFromRecord($key, $record);
-            }
-
-            return $items;
-        });
+        return $this->withSharedLock(fn(): array => $this->fetchStoredItems($keys));
     }
 
     /** @param list<string> $tags */
@@ -320,17 +264,7 @@ public function saveItems(array $items): bool
             $records[$this->map($item->getKey())] = $this->encodeItem($item, $expiration['expiresAt']);
         }
 
-        return $this->withExclusiveLock(function () use ($records, $expired): bool {
-            $store = $this->loadStore();
-            foreach ($expired as $key) {
-                unset($store[$key]);
-            }
-            foreach ($records as $key => $blob) {
-                $store[$key] = $blob;
-            }
-
-            return $this->store($store);
-        });
+        return $this->withExclusiveLock(fn(): bool => $this->updateStore($records, $expired));
     }
 
     /** @param array<string, string> $generations */
@@ -384,6 +318,26 @@ private function cachedRecord(array $store, string $key, string $mapped): ?Cache
             : null;
     }
 
+    private function consumeRecord(string $key, string $mapped): CacheItemInterface
+    {
+        $store = $this->loadStore();
+        $blob = $store[$mapped] ?? null;
+        if (!is_string($blob)) {
+            return $this->genericMiss($key);
+        }
+
+        $record = $this->decodeRecordFromBlob($blob, $key);
+        unset($store[$mapped]);
+        if (!$this->store($store)) {
+            throw new RuntimeException('Unable to persist shared-memory atomic consume.');
+        }
+        if (!$record instanceof CacheRecord || !$this->recordTagsAreCurrent($record, $store)) {
+            return $this->genericMiss($key);
+        }
+
+        return $this->genericItemFromRecord($key, $record);
+    }
+
     private function createTokenFile(): string
     {
         $directory = rtrim(sys_get_temp_dir(), DIRECTORY_SEPARATOR)
@@ -411,6 +365,52 @@ private function createTokenFile(): string
         return $tokenFile;
     }
 
+    /**
+     * @param list<string> $keys
+     * @return array<string, CacheItem>
+     */
+    private function fetchStoredItems(array $keys): array
+    {
+        $store = $this->loadStore();
+        $items = [];
+        foreach ($keys as $key) {
+            $mapped = $this->map($key);
+            $blob = $store[$mapped] ?? null;
+            $record = is_string($blob) ? $this->decodeRecordFromBlob($blob, $key) : null;
+            $items[$key] = $record === null
+                ? $this->genericMiss($key)
+                : $this->genericItemFromRecord($key, $record);
+        }
+
+        return $items;
+    }
+
+    /**
+     * @param list<string> $tags
+     * @return array<string, string>
+     */
+    private function initializeTagGenerations(array $tags): array
+    {
+        $store = $this->loadStore();
+        $generations = [];
+        $changed = false;
+        foreach ($tags as $tag) {
+            $mapped = $this->mapTag($tag);
+            $generation = self::normalizeGeneration($store[$mapped] ?? null);
+            if ($generation === null) {
+                $generation = self::newGeneration();
+                $store[$mapped] = $generation;
+                $changed = true;
+            }
+            $generations[$tag] = $generation;
+        }
+        if ($changed && !$this->store($store)) {
+            throw new RuntimeException('Unable to initialize shared-memory tag generations.');
+        }
+
+        return $generations;
+    }
+
     /**
      * @phpstan-return array<string, string>
      */
@@ -502,6 +502,23 @@ private function store(array $store): bool
         return shm_put_var($this->segment, self::VAR_ID, $store);
     }
 
+    /**
+     * @param array<string, string> $records
+     * @param list<string> $expired
+     */
+    private function updateStore(array $records, array $expired): bool
+    {
+        $store = $this->loadStore();
+        foreach ($expired as $key) {
+            unset($store[$key]);
+        }
+        foreach ($records as $key => $blob) {
+            $store[$key] = $blob;
+        }
+
+        return $this->store($store);
+    }
+
     /**
      * @template T
      * @param callable $operation The operation to run while locked.
diff --git a/src/Cache/Adapter/WeakMapCacheAdapter.php b/src/Cache/Adapter/WeakMapCacheAdapter.php
index cedbcfb..35a6b61 100644
--- a/src/Cache/Adapter/WeakMapCacheAdapter.php
+++ b/src/Cache/Adapter/WeakMapCacheAdapter.php
@@ -177,8 +177,7 @@ public function multiFetch(array $keys): array
         $staleScalar = [];
         foreach ($keys as $key) {
             $mapped = $this->map($key);
-            $reference = $this->weakRefs[$mapped] ?? null;
-            $object = $reference instanceof WeakReference ? $reference->get() : null;
+            $object = ($this->weakRefs[$mapped] ?? null)?->get();
             $expiresAt = $this->weakExpires[$mapped] ?? null;
             if (is_object($object) && !CachePayloadCodec::isExpired($expiresAt)) {
                 $items[$key] = new CacheItem(
diff --git a/src/Cache/Cache.php b/src/Cache/Cache.php
index 047c095..b95f8c4 100644
--- a/src/Cache/Cache.php
+++ b/src/Cache/Cache.php
@@ -544,11 +544,7 @@ public function remember(
             $generations = $this->captureTagGenerations($tags);
             $this->metric('remember_unlocked_compute');
             $value = $resolver();
-            if ($generations !== null && $this->tagGenerationsUnchanged($generations)) {
-                $this->storeResolved($key, $value, $ttl, $generations);
-            } elseif ($tags !== []) {
-                $this->metric('remember_discarded_after_tag_change');
-            }
+            $this->storeRemembered($key, $value, $ttl, $generations, $tags !== []);
 
             return $value;
         }
@@ -573,14 +569,7 @@ public function remember(
 
                 return $value;
             }
-            if ($generations === null || !$this->tagGenerationsUnchanged($generations)) {
-                if ($tags !== []) {
-                    $this->metric('remember_discarded_after_tag_change');
-                }
-
-                return $value;
-            }
-            $this->storeResolved($key, $value, $ttl, $generations);
+            $this->storeRemembered($key, $value, $ttl, $generations, $tags !== []);
 
             return $value;
         } finally {
@@ -858,6 +847,24 @@ private function stampedeLockKey(string $key): string
         return 'cachelayer:remember:' . hash('xxh128', $this->namespace . "\0" . $key);
     }
 
+    /** @param array<string, string>|null $generations */
+    private function storeRemembered(
+        string $key,
+        mixed $value,
+        ?int $ttl,
+        ?array $generations,
+        bool $tagged,
+    ): void {
+        if ($generations !== null && $this->tagGenerationsUnchanged($generations)) {
+            $this->storeResolved($key, $value, $ttl, $generations);
+
+            return;
+        }
+        if ($tagged) {
+            $this->metric('remember_discarded_after_tag_change');
+        }
+    }
+
     /** @param array<string, string> $generations */
     private function storeResolved(string $key, mixed $value, ?int $ttl, array $generations): void
     {
diff --git a/src/Integration/Runwire/RunwireIntegration.php b/src/Integration/Runwire/RunwireIntegration.php
index cfa12f8..959ac73 100644
--- a/src/Integration/Runwire/RunwireIntegration.php
+++ b/src/Integration/Runwire/RunwireIntegration.php
@@ -85,7 +85,8 @@ public static function flushMemoizers(): void
 
     public static function memoizer(): ?Memoizer
     {
-        $request = self::current()?->request;
+        $context = self::current();
+        $request = $context?->request;
         if ($request !== null) {
             $memoizer = $request->attribute(self::MEMOIZER_ATTRIBUTE);
             if ($memoizer instanceof Memoizer) {
@@ -98,7 +99,8 @@ public static function memoizer(): ?Memoizer
             return $memoizer;
         }
 
-        if (self::$runtime?->persistent === true && self::$runtime->concurrent) {
+        $runtime = $context->runtime ?? self::$runtime;
+        if ($runtime?->persistent === true && $runtime->concurrent) {
             return null;
         }
 
@@ -107,7 +109,8 @@ public static function memoizer(): ?Memoizer
 
     public static function onceMemoizer(): ?OnceMemoizer
     {
-        $request = self::current()?->request;
+        $context = self::current();
+        $request = $context?->request;
         if ($request !== null) {
             $memoizer = $request->attribute(self::ONCE_MEMOIZER_ATTRIBUTE);
             if ($memoizer instanceof OnceMemoizer) {
@@ -120,7 +123,8 @@ public static function onceMemoizer(): ?OnceMemoizer
             return $memoizer;
         }
 
-        if (self::$runtime?->persistent === true && self::$runtime->concurrent) {
+        $runtime = $context->runtime ?? self::$runtime;
+        if ($runtime?->persistent === true && $runtime->concurrent) {
             return null;
         }
 
@@ -140,15 +144,17 @@ public static function release(?RuntimeContext $runtime = null): void
 
     public static function runtime(): ?RuntimeContext
     {
-        return self::$runtime;
+        return self::current()->runtime ?? self::$runtime;
     }
 
+    /** Borrow an explicit host runtime for this callback without global lifecycle ownership. */
     public static function share(
         ?RequestContext $request,
         ?CoroutineScope $scope,
         callable $callback,
+        ?RuntimeContext $runtime = null,
     ): mixed {
-        $runtime = self::$runtime;
+        $runtime ??= self::runtime();
         if ($runtime === null) {
             return $callback();
         }
@@ -207,7 +213,7 @@ public static function sleep(float $seconds): void
 
     public static function supports(RuntimeCapability $capability): bool
     {
-        return self::$runtime?->supports($capability) ?? false;
+        return self::runtime()?->supports($capability) ?? false;
     }
 
     private static function flushGlobalMemoizers(): void
diff --git a/src/Node/Adapter/NodeCacheAdapter.php b/src/Node/Adapter/NodeCacheAdapter.php
index bc0e859..6f340a8 100644
--- a/src/Node/Adapter/NodeCacheAdapter.php
+++ b/src/Node/Adapter/NodeCacheAdapter.php
@@ -323,6 +323,19 @@ private function attempt(callable $operation, mixed $fallback, string $failureMe
         }
     }
 
+    private function copyItemTo(InternalCachePoolInterface $pool, CacheItemInterface $item): CacheItemInterface
+    {
+        $target = $pool->createItem($item->getKey())->set($item->get());
+        if ($item instanceof CacheItem) {
+            $target->expiresAfter($item->ttlSeconds());
+            if ($target instanceof CacheItem) {
+                $target->setTagGenerations($item->getTagGenerations());
+            }
+        }
+
+        return $target;
+    }
+
     private function disableL1(): void
     {
         if (!$this->l1Readable) {
@@ -383,9 +396,10 @@ private function readL1(array $keys): array
             $item = $l1Items[$key] ?? null;
             if ($item instanceof CacheItemInterface && $item->isHit()) {
                 $results[$key] = $this->nodeItem($item);
-            } else {
-                $misses[] = $key;
+
+                continue;
             }
+            $misses[] = $key;
         }
         $this->metric('l1_batch_hit', count($keys) - count($misses));
         $this->metric('l1_batch_miss', count($misses));
@@ -437,14 +451,7 @@ private function saveInto(
         $targets = [];
         foreach ($items as $item) {
             $key = $item->getKey();
-            $target = $pool->createItem($key)->set($item->get());
-            if ($item instanceof CacheItem) {
-                $target->expiresAfter($item->ttlSeconds());
-                if ($target instanceof CacheItem) {
-                    $target->setTagGenerations($item->getTagGenerations());
-                }
-            }
-            $targets[$key] = $target;
+            $targets[$key] = $this->copyItemTo($pool, $item);
         }
 
         return $this->attempt(fn(): bool => $pool->saveItems($targets), false, $failureMetric);
@@ -455,13 +462,7 @@ private function saveOneInto(
         CacheItemInterface $item,
         string $failureMetric,
     ): bool {
-        $target = $pool->createItem($item->getKey())->set($item->get());
-        if ($item instanceof CacheItem) {
-            $target->expiresAfter($item->ttlSeconds());
-            if ($target instanceof CacheItem) {
-                $target->setTagGenerations($item->getTagGenerations());
-            }
-        }
+        $target = $this->copyItemTo($pool, $item);
 
         return $this->attempt(fn(): bool => $pool->save($target), false, $failureMetric);
     }
diff --git a/src/Node/Adapter/NodeSqliteCacheAdapter.php b/src/Node/Adapter/NodeSqliteCacheAdapter.php
index 9b6863f..3531956 100644
--- a/src/Node/Adapter/NodeSqliteCacheAdapter.php
+++ b/src/Node/Adapter/NodeSqliteCacheAdapter.php
@@ -340,12 +340,12 @@ public function saveMany(array $items): bool
         try {
             $this->connection->beginTransaction();
             $this->ownsTransaction = true;
-            if ($expired !== [] && !$this->deleteItems($expired)) {
+            if (!$this->deleteItems($expired)) {
                 $this->rollBack();
 
                 return false;
             }
-            if ($rows !== [] && !$this->upsertRows($rows)) {
+            if (!$this->upsertRows($rows)) {
                 $this->rollBack();
 
                 return false;
diff --git a/src/functions.php b/src/functions.php
index 40d626d..7393470 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -56,9 +56,11 @@ function once(callable $callback): mixed
     {
         $memoizer = RunwireIntegration::onceMemoizer();
 
-        return $memoizer === null
-            ? $callback()
-            : $memoizer->once($callback, 1);
+        if ($memoizer === null) {
+            return $callback();
+        }
+
+        return $memoizer->once($callback, 1);
     }
 }
 
diff --git a/tests/Cache/CachePayloadCodecSecurityTest.php b/tests/Cache/CachePayloadCodecSecurityTest.php
index 4e0c990..7200660 100644
--- a/tests/Cache/CachePayloadCodecSecurityTest.php
+++ b/tests/Cache/CachePayloadCodecSecurityTest.php
@@ -217,3 +217,39 @@
     expect(fn() => $codec->encode($value, null))->toThrow(InvalidArgumentException::class, 'nesting depth')
         ->and(fn() => $cache->set('nested', $value))->toThrow(\Infocyph\CacheLayer\Exceptions\CacheBackendException::class);
 })->with([false, true])->with([false, true])->with([127, 128, 129])->with(['scalar leaf' => ['leaf'], 'empty array leaf' => [[]]]);
+
+
+test('payload codec rejects malformed namespace and tag generations', function (mixed $invalid) {
+    $codec = new CachePayloadCodec();
+    $record = [
+        'format' => 2,
+        'encoding' => 'native',
+        'value' => null,
+        'expires' => null,
+        'tags' => [],
+        'namespace' => null,
+    ];
+
+    expect($codec->decode('cl2:' . serialize(array_replace($record, ['namespace' => $invalid]))))
+        ->toBeNull()
+        ->and($codec->decode('cl2:' . serialize(array_replace($record, ['tags' => ['group' => $invalid]]))))
+        ->toBeNull();
+})->with([
+    'empty' => [''],
+    'short hex' => [str_repeat('a', 31)],
+    'long hex' => [str_repeat('a', 33)],
+    'non-hex' => [str_repeat('z', 32)],
+    'integer' => [123],
+    'array' => [[]],
+]);
+
+test('payload codec preserves valid uppercase generations and null values', function () {
+    $codec = new CachePayloadCodec();
+    $generation = str_repeat('AB', 16);
+    $record = $codec->decode($codec->encode(null, null, ['group' => $generation], $generation));
+
+    expect($record)->not->toBeNull()
+        ->and($record->value)->toBeNull()
+        ->and($record->namespaceGeneration)->toBe($generation)
+        ->and($record->tags)->toBe(['group' => $generation]);
+});
diff --git a/tests/Integration/RunwireIntegrationTest.php b/tests/Integration/RunwireIntegrationTest.php
index 28078c5..b0786e2 100644
--- a/tests/Integration/RunwireIntegrationTest.php
+++ b/tests/Integration/RunwireIntegrationTest.php
@@ -267,3 +267,64 @@ static function (): void {
 
     expect($result)->toBe([1, 1, 1]);
 });
+
+it('borrows an explicit runtime without global binding and restores nested task contexts', function (): void {
+    $runtime = \Infocyph\Runwire\RuntimeContext::standalone();
+    $request = \Infocyph\Runwire\RequestContext::create($runtime);
+    $nested = \Infocyph\Runwire\RequestContext::create($runtime);
+    $before = \Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::runtime();
+    try {
+        \Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::share($request, null, static function () use ($runtime, $request, $nested): void {
+            expect(\Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::runtime())->toBe($runtime)
+                ->and(\Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::current()?->request)->toBe($request);
+            expect(fn() => \Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::share($nested, null, static function (): void {
+                throw new RuntimeException('nested failure');
+            }))->toThrow(RuntimeException::class, 'nested failure');
+            expect(\Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::current()?->request)->toBe($request);
+        }, $runtime);
+        expect(\Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::runtime())->toBe($before)
+            ->and(\Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::current())->toBeNull();
+    } finally {
+        $request->complete();
+        $nested->complete();
+    }
+});
+
+it('keeps explicitly passed request scopes separate across overlapping Fibers', function (): void {
+    $runtime = \Infocyph\Runwire\RuntimeContext::standalone();
+    $one = \Infocyph\Runwire\RequestContext::create($runtime);
+    $two = \Infocyph\Runwire\RequestContext::create($runtime);
+    $work = static fn($request) => \Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::share($request, null, static function () use ($request): object {
+        $memoizer = \Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::memoizer();
+        Fiber::suspend($memoizer);
+        expect(\Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::current()?->request)->toBe($request);
+
+        return $request;
+    }, $runtime);
+    $first = new Fiber(static fn() => $work($one));
+    $second = new Fiber(static fn() => $work($two));
+    try {
+        $firstMemoizer = $first->start();
+        $secondMemoizer = $second->start();
+        expect($firstMemoizer)->not->toBe($secondMemoizer);
+        $second->resume();
+        $first->resume();
+        expect($first->getReturn())->toBe($one)
+            ->and($second->getReturn())->toBe($two)
+            ->and(\Infocyph\CacheLayer\Integration\Runwire\RunwireIntegration::current())->toBeNull();
+    } finally {
+        $one->complete();
+        $two->complete();
+    }
+});
+
+it('bypasses global memoizers for an explicitly passed concurrent runtime without a request', function (): void {
+    $runtime = cacheLayerRunwireContext(true, true);
+    RunwireIntegration::share(null, null, static function () use ($runtime): void {
+        expect(RunwireIntegration::runtime())->toBe($runtime)
+            ->and(RunwireIntegration::supports(RuntimeCapability::RUNWIRE_COROUTINES))->toBeTrue()
+            ->and(RunwireIntegration::memoizer())->toBeNull()
+            ->and(RunwireIntegration::onceMemoizer())->toBeNull();
+    }, $runtime);
+    expect(RunwireIntegration::runtime())->toBeNull();
+});
diff --git a/tests/Memoize/MemoizeTest.php b/tests/Memoize/MemoizeTest.php
index 8b77588..77f52db 100644
--- a/tests/Memoize/MemoizeTest.php
+++ b/tests/Memoize/MemoizeTest.php
@@ -242,3 +242,19 @@ public function next(): int
     expect($first->get($callback))->toBe(1)
         ->and($runs)->toBe(1);
 });
+
+
+it('once() caches null results without repeating callback side effects', function () {
+    $runs = 0;
+    $callback = static function () use (&$runs): mixed {
+        $runs++;
+
+        return null;
+    };
+
+    for ($attempt = 0; $attempt < 3; $attempt++) {
+        expect(once($callback))->toBeNull();
+    }
+
+    expect($runs)->toBe(1);
+});