diff --git a/formula/src/main/java/com/instacart/formula/Inspector.kt b/formula/src/main/java/com/instacart/formula/Inspector.kt
index dcf20e43..5027a7aa 100644
--- a/formula/src/main/java/com/instacart/formula/Inspector.kt
+++ b/formula/src/main/java/com/instacart/formula/Inspector.kt
@@ -65,10 +65,11 @@ interface Inspector {
      * Called when a state change happens
      *
      * @param formulaType Formula type used to filter for specific events.
+     * @param event Event that triggered this state change
      * @param old Previous state value
      * @param new New state value
      */
-    fun onStateChanged(formulaType: KClass<*>, old: Any?, new: Any?) = Unit
+    fun onStateChanged(formulaType: KClass<*>, event: Any?, old: Any?, new: Any?) = Unit
 
     /**
      * Called when [FormulaRuntime.run] is called. This method in combination with [onRunFinished]
diff --git a/formula/src/main/java/com/instacart/formula/internal/FormulaManagerImpl.kt b/formula/src/main/java/com/instacart/formula/internal/FormulaManagerImpl.kt
index c880738b..f53433a3 100644
--- a/formula/src/main/java/com/instacart/formula/internal/FormulaManagerImpl.kt
+++ b/formula/src/main/java/com/instacart/formula/internal/FormulaManagerImpl.kt
@@ -78,7 +78,7 @@ internal class FormulaManagerImpl<Input, State, Output>(
         return terminated
     }
 
-    fun handleTransitionResult(result: Transition.Result<State>) {
+    fun handleTransitionResult(event: Any?, result: Transition.Result<State>) {
         val effects = result.effects
         if (terminated) {
             // State transitions are ignored, let's just execute side-effects.
@@ -93,7 +93,12 @@ internal class FormulaManagerImpl<Input, State, Output>(
 
                 globalEvaluationId += 1
 
-                inspector?.onStateChanged(loggingType, old, result.state)
+                inspector?.onStateChanged(
+                    formulaType = loggingType,
+                    event = event,
+                    old = old,
+                    new = result.state,
+                )
             }
         }
 
@@ -180,7 +185,13 @@ internal class FormulaManagerImpl<Input, State, Output>(
             }
         }
 
-        val snapshot = SnapshotImpl(input, state, evaluationId, listeners, this)
+        val snapshot = SnapshotImpl(
+            input = input,
+            state = state,
+            associatedEvaluationId = evaluationId,
+            listeners = listeners,
+            delegate = this,
+        )
         val result = formula.evaluate(snapshot)
 
         if (isValidationEnabled) {
diff --git a/formula/src/main/java/com/instacart/formula/internal/ListInspector.kt b/formula/src/main/java/com/instacart/formula/internal/ListInspector.kt
index cedc9ae6..b72370e2 100644
--- a/formula/src/main/java/com/instacart/formula/internal/ListInspector.kt
+++ b/formula/src/main/java/com/instacart/formula/internal/ListInspector.kt
@@ -35,8 +35,8 @@ internal class ListInspector(
         forEachInspector { onActionFinished(formulaType, action) }
     }
 
-    override fun onStateChanged(formulaType: KClass<*>, old: Any?, new: Any?) {
-        forEachInspector { onStateChanged(formulaType, old, new) }
+    override fun onStateChanged(formulaType: KClass<*>, event: Any?, old: Any?, new: Any?) {
+        forEachInspector { onStateChanged(formulaType, event, old, new) }
     }
 
     override fun onRunStarted(evaluate: Boolean) {
diff --git a/formula/src/main/java/com/instacart/formula/internal/SnapshotImpl.kt b/formula/src/main/java/com/instacart/formula/internal/SnapshotImpl.kt
index 01cefbd4..a8fa7985 100644
--- a/formula/src/main/java/com/instacart/formula/internal/SnapshotImpl.kt
+++ b/formula/src/main/java/com/instacart/formula/internal/SnapshotImpl.kt
@@ -102,7 +102,7 @@ internal class SnapshotImpl<out Input, State> internal constructor(
             return
         }
 
-        delegate.handleTransitionResult(result)
+        delegate.handleTransitionResult(event, result)
     }
 
     private fun ensureNotRunning() {
diff --git a/formula/src/test/java/com/instacart/formula/internal/TestInspector.kt b/formula/src/test/java/com/instacart/formula/internal/TestInspector.kt
index 4d2cfffc..2af104ec 100644
--- a/formula/src/test/java/com/instacart/formula/internal/TestInspector.kt
+++ b/formula/src/test/java/com/instacart/formula/internal/TestInspector.kt
@@ -36,7 +36,7 @@ class TestInspector : Inspector {
         events.add("action-finished: ${formulaType.qualifiedName}")
     }
 
-    override fun onStateChanged(formulaType: KClass<*>, old: Any?, new: Any?) {
+    override fun onStateChanged(formulaType: KClass<*>, event: Any?, old: Any?, new: Any?) {
         events.add("state-changed: ${formulaType.qualifiedName}")
     }