diff --git a/CHANGELOG.md b/CHANGELOG.md
index f723d8d..8b5f140 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,11 +2,15 @@
 
 ## v1.2.x
 
-- Add Batch IP from
-    - https://speakerdeck.com/alli83/symfony-messenger-et-ses-messages-a-la-queleuleu-dot-dot-dot-et-sil-etait-temps-de-grouper
-    - https://wolfgang-klinger.medium.com/how-to-handle-messages-in-batches-with-symfony-messenger-c91b5aa1c8b1
-    - https://github.com/wazum/symfony-messenger-batch
-- YFlow rework
+- Add new Interface Flow\AsyncHandlerInterface to control the Event::SYNC step when processing an IP
+    - Add Flow\AsyncHandler\AsyncHandler the default handler when Event::SYNC is dispatched
+    - Add Batch IP with Flow\AsyncHandler\BatchAsyncHandler from
+        - https://speakerdeck.com/alli83/symfony-messenger-et-ses-messages-a-la-queleuleu-dot-dot-dot-et-sil-etait-temps-de-grouper
+        - https://wolfgang-klinger.medium.com/how-to-handle-messages-in-batches-with-symfony-messenger-c91b5aa1c8b1
+        - https://github.com/wazum/symfony-messenger-batch
+    - Add Flow\AsyncHandler\DeferAsyncHandler to gain granular control on the async Event::SYNC step event
+- Flow\Flow\YFlow rework
+- Add more exemples in `examples/yflow.php` to play with Y-Combinators
 - Update DX for Flow\DriverInterface : add `defer` to gain much granular control on asynchronous callbacks
 
 ## v1.2.0
diff --git a/docs/src/content/en/docs/getting-started/async-handler.md b/docs/src/content/en/docs/getting-started/async-handler.md
index 3db793b..56ffd18 100644
--- a/docs/src/content/en/docs/getting-started/async-handler.md
+++ b/docs/src/content/en/docs/getting-started/async-handler.md
@@ -25,6 +25,12 @@ This is the default one. Ip is async processed immediately.
 
 This async process Ip as batch capability : the handler will wait for a certain amount of async messages ($batchSize) to be processed before pushing them.
 
+## DeferAsyncHandler
+
+This async process Ip to offer defer capability : the handler will pass [$data, $defer] as entry for the job. In that case, the job can fine control the async process. $defer is a callable that embark two callbacks
+- an complete callback to store result
+- an async callback to go to the next async call.
+
 ## Make your Async Handler
 
 You can make your custom Ip strategy by implementing `Flow\AsyncHandlerInterface`
diff --git a/examples/flow.php b/examples/flow.php
index e697db3..26edddd 100644
--- a/examples/flow.php
+++ b/examples/flow.php
@@ -18,7 +18,7 @@
 use Flow\Ip;
 use Flow\IpStrategy\MaxIpStrategy;
 
-$driver = match (random_int(1, 4)) {
+$driver = match (random_int(4, 4)) {
     1 => new AmpDriver(),
     2 => new FiberDriver(),
     3 => new ReactDriver(),
diff --git a/src/Driver/SpatieDriver.php b/src/Driver/SpatieDriver.php
index 88612a4..fafcef3 100644
--- a/src/Driver/SpatieDriver.php
+++ b/src/Driver/SpatieDriver.php
@@ -60,16 +60,32 @@ public function async(Closure $callback): Closure
         };
     }
 
+    public function defer(Closure $callback): mixed
+    {
+        return null;
+    }
+
     public function await(array &$stream): void
     {
-        $async = function ($ip, $fnFlows, $index, $onResolve) {
-            $async = $this->async($fnFlows[$index]['job']);
+        $async = function (Closure $job) {
+            return function (mixed $data) use ($job) {
+                $async = $this->async($job);
+
+                $next = fn($value) => $value;
+                if ($data === null) {
+                    $async($next)();
+                } else {
+                    $async($next)($data);
+                }
 
-            if ($ip->data === null) {
-                return $async($onResolve)();
-            }
+                return static function($onResolve) use ($next) {
+                    $next($onResolve);
+                };
+            };
+        };
 
-            return $async($onResolve)($ip->data);
+        $defer = function (Closure $job) use ($async) {
+            return $async($job);
         };
 
         $nextIp = null;
@@ -78,7 +94,7 @@ public function await(array &$stream): void
                 foreach ($stream['dispatchers'] as $index => $dispatcher) {
                     $nextIp = $dispatcher->dispatch(new PullEvent(), Event::PULL)->getIp();
                     if ($nextIp !== null) {
-                        $stream['dispatchers'][$index]->dispatch(new AsyncEvent($async, $nextIp, $stream['fnFlows'], $index, static function ($data) use (&$stream, $index, $nextIp) {
+                        $stream['dispatchers'][$index]->dispatch(new AsyncEvent($async, $defer, $stream['fnFlows'][$index]['job'], $nextIp, static function ($data) use (&$stream, $index, $nextIp) {
                             if ($data instanceof RuntimeException and array_key_exists($index, $stream['fnFlows']) && $stream['fnFlows'][$index]['errorJob'] !== null) {
                                 $stream['fnFlows'][$index]['errorJob']($data);
                             } elseif (array_key_exists($index + 1, $stream['fnFlows'])) {
diff --git a/src/Driver/SwooleDriver.php b/src/Driver/SwooleDriver.php
index ee2e846..30846bd 100644
--- a/src/Driver/SwooleDriver.php
+++ b/src/Driver/SwooleDriver.php
@@ -54,6 +54,11 @@ public function async(Closure $callback): Closure
         };
     }
 
+    public function defer(Closure $callback): mixed
+    {
+        return null;
+    }
+
     public function await(array &$stream): void
     {
         $async = function ($ip, $fnFlows, $index, $onResolve) {