fix(core): prevent calling onStateChange recurively when changing state from within onStateChange (#1209)

Author: NathanFlurry

packages/rivetkit/fixtures/driver-test-suite/actor-onstatechange.ts

@@ -0,0 +1,44 @@
+import { actor } from "rivetkit";
+
+export const onStateChangeActor = actor({
+	onAuth: () => {},
+	state: {
+		value: 0,
+		changeCount: 0,
+	},
+	actions: {
+		// Action that modifies state - should trigger onStateChange
+		setValue: (c, newValue: number) => {
+			c.state.value = newValue;
+			return c.state.value;
+		},
+		// Action that modifies state multiple times - should trigger onStateChange for each change
+		incrementMultiple: (c, times: number) => {
+			for (let i = 0; i < times; i++) {
+				c.state.value++;
+			}
+			return c.state.value;
+		},
+		// Action that doesn't modify state - should NOT trigger onStateChange
+		getValue: (c) => {
+			return c.state.value;
+		},
+		// Action that reads and returns without modifying - should NOT trigger onStateChange
+		getDoubled: (c) => {
+			const doubled = c.state.value * 2;
+			return doubled;
+		},
+		// Get the count of how many times onStateChange was called
+		getChangeCount: (c) => {
+			return c.state.changeCount;
+		},
+		// Reset change counter for testing
+		resetChangeCount: (c) => {
+			c.state.changeCount = 0;
+		},
+	},
+	// Track onStateChange calls
+	onStateChange: (c) => {
+		c.state.changeCount++;
+	},
+});