Add new delta interface

CLAUDE.md

@@ -72,7 +72,7 @@ Only consider your changes complete when `make check` passes with all green chec
 
 StateFlow uses a **two-step execution model** that separates setup from execution:
 
-1. **Setup Phase**: `StateFlow::transition(State, array $delta)` returns a `StateWorker`
+1. **Setup Phase**: `StateFlow::transition(State, Delta $delta)` returns a `StateWorker`
 2. **Execution Phase**: `StateWorker::execute()` runs the transition
 
 This separation enables:
@@ -131,15 +131,15 @@ interface State {
 }
 ```
 
-Users define their own merge strategy in `with()`. The `$changes` array is the delta passed to `transition()`.
+Users define their own merge strategy in `with()`. The `$changes` array is converted from the Delta object passed to `transition()`.
 
 ### Configuration Provider
 
 Lazy-loaded configuration based on current state and desired delta:
 
 ```php
-$configProvider = function(State $currentState, array $delta): Configuration {
-    return match ($delta['status'] ?? null) {
+$configProvider = function(State $currentState, Delta $delta): Configuration {
+    return match ($delta->get('status')) {
         'processing' => new Configuration(
             transitionGates: [new HasInventoryGate()],
             actions: [new ChargePaymentAction(), new ReserveInventoryAction()],

README.md

@@ -73,7 +73,7 @@ $stateFlow = new StateFlow(
 
 // Execute transition with automatic locking
 $order = new Order('pending');
-$worker = $stateFlow->transition($order, ['status' => 'processing']);
+$worker = $stateFlow->transition($order, new ArrayDelta(['status' => 'processing']));
 $context = $worker->execute();
 
 
@@ -98,12 +98,12 @@ Specify only what changes:
 
 ```php
 // Just this
-$worker = $stateFlow->transition($state, ['status' => 'published']);
+$worker = $stateFlow->transition($state, new ArrayDelta(['status' => 'published']));
 $context = $worker->execute();
 
 
 // Not this
-$worker = $stateFlow->transition($state, ['status' => 'published', 'author' => 'same', 'created' => 'same', ...]);
+$worker = $stateFlow->transition($state, new ArrayDelta(['status' => 'published', 'author' => 'same', 'created' => 'same', ...]));
 $context = $worker->execute();
 ```
 
@@ -112,7 +112,7 @@ $context = $worker->execute();
 The `StateWorker` gives you full control over the workflow execution:
 
 ```php
-$worker = $stateFlow->transition($state, ['status' => 'published']);
+$worker = $stateFlow->transition($state, new ArrayDelta(['status' => 'published']));
 
 // 1. Run gates first
 $gateResult = $worker->runGates();
@@ -149,7 +149,7 @@ $stateFlow = new StateFlow(
 );
 
 // This transition will be automatically locked
-$worker = $stateFlow->transition($state, ['status' => 'published']);
+$worker = $stateFlow->transition($state, new ArrayDelta(['status' => 'published']));
 $context = $worker->execute();
 ```
 
@@ -249,8 +249,8 @@ class OrderState implements State {
 }
 
 // 2. Configure workflow based on transition type
-$configProvider = function(State $state, array $delta): Configuration {
-    return match ($delta['status'] ?? null) {
+$configProvider = function(State $state, Delta $delta): Configuration {
+    return match ($delta->get('status')) {
         'processing' => new Configuration(
             transitionGates: [new HasInventoryGate($inventory)],
             actions: [
@@ -273,7 +273,7 @@ $stateFlow = new StateFlow(
     eventDispatcher: new MetricsDispatcher(),
     lockProvider: new RedisLockProvider($redis),
     lockKeyProvider: new class implements LockKeyProvider {
-        public function getLockKey(State $state, array $delta): string {
+        public function getLockKey(State $state, Delta $delta): string {
             return "order:" . $state->toArray()['id'];
         }
     },
@@ -282,7 +282,7 @@ $stateFlow = new StateFlow(
 // 4. Execute with race protection
 try {
     $order = new OrderState('ORD-123', 'pending', 99.99);
-    $worker = $stateFlow->transition($order, ['status' => 'processing']);
+    $worker = $stateFlow->transition($order, new ArrayDelta(['status' => 'processing']));
     $context = $worker->execute();
 
     if ($context->isCompleted()) {

docs/architecture.md

@@ -18,11 +18,11 @@ Users specify only what should change, not the entire final state:
 
 ```php
 // Good: Delta approach
-$worker = $stateFlow->transition($orderState, ['status' => 'published']);
+$worker = $stateFlow->transition($orderState, new ArrayDelta(['status' => 'published']));
 $context = $worker->execute();
 
 // Avoided: Full state (verbose and error-prone)
-$stateFlow->transition($orderState, ['status' => 'published', 'author' => 'same', 'created' => 'same', ...]);
+$stateFlow->transition($orderState, new ArrayDelta(['status' => 'published', 'author' => 'same', 'created' => 'same', ...]));
 ```
 
 **Rationale:** With rich state objects, deltas are more ergonomic and show clear intent.
@@ -48,14 +48,14 @@ The `StateWorker` allows for fine-grained control over the execution flow.
 **One-Shot Execution:**
 
 ```php
-$worker = $stateFlow->transition($state, ['status' => 'published']);
+$worker = $stateFlow->transition($state, new ArrayDelta(['status' => 'published']));
 $context = $worker->execute(); // Runs gates and actions
 ```
 
 **Step-Through Execution:**
 
 ```php
-$worker = $stateFlow->transition($state, ['status' => 'published']);
+$worker = $stateFlow->transition($state, new ArrayDelta(['status' => 'published']));
 $gateResult = $worker->runGates();
 if ($gateResult->shouldStopTransition()) {
     // Handle failed transition
@@ -75,7 +75,7 @@ class GenerateThumbnailsAction implements Action {
 }
 
 // Serialize and wait
-$worker = $stateFlow->transition($state, ['status' => 'published']);
+$worker = $stateFlow->transition($state, new ArrayDelta(['status' => 'published']));
 $context = $worker->execute();
 if ($context->isPaused()) {
     saveToDatabase($context->serialize());
@@ -120,7 +120,7 @@ $stateFlow = new StateFlow(
 );
 
 // The worker will use the flows's lock provider
-$worker = $stateFlow->transition($state, ['status' => 'published']);
+$worker = $stateFlow->transition($state, new ArrayDelta(['status' => 'published']));
 $context = $worker->execute();
 ```
 
@@ -210,7 +210,7 @@ Users implement their own merge logic in `with()`.
 **Why:** Allows dynamic gate/action selection based on what's changing.
 
 ```php
-$configProvider = function(State $currentState, array $desiredDelta): Configuration {
+$configProvider = function(State $currentState, Delta $desiredDelta): Configuration {
     // ... return Configuration based on state and delta
 };
 ```