Use WorkflowReplayer for proper replay determinism tests

Previously the tests just ran workflows forward. Now they capture
the event history after execution and replay it with
WorkflowReplayer.replayWorkflowExecution(), which will throw
NonDeterministicException if the workflow code generates different
commands on replay.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: donald-pinckney

temporal-spring-ai/src/test/java/io/temporal/springai/WorkflowDeterminismTest.java

@@ -4,12 +4,15 @@
 
 import io.temporal.client.WorkflowClient;
 import io.temporal.client.WorkflowOptions;
+import io.temporal.client.WorkflowStub;
+import io.temporal.common.WorkflowExecutionHistory;
 import io.temporal.springai.activity.ChatModelActivityImpl;
 import io.temporal.springai.chat.TemporalChatClient;
 import io.temporal.springai.model.ActivityChatModel;
 import io.temporal.springai.tool.DeterministicTool;
 import io.temporal.springai.tool.SideEffectTool;
 import io.temporal.testing.TestWorkflowEnvironment;
+import io.temporal.testing.WorkflowReplayer;
 import io.temporal.worker.Worker;
 import io.temporal.workflow.WorkflowInterface;
 import io.temporal.workflow.WorkflowMethod;
@@ -26,8 +29,8 @@
 import org.springframework.ai.tool.annotation.Tool;
 
 /**
- * Verifies that workflows using ActivityChatModel with tools execute without non-determinism
- * errors.
+ * Verifies that workflows using ActivityChatModel with tools are deterministic by running them to
+ * completion and then replaying from the captured history.
  */
 class WorkflowDeterminismTest {
 
@@ -48,13 +51,11 @@ void tearDown() {
   }
 
   @Test
-  void workflowWithChatModel_completesSuccessfully() {
+  void workflowWithChatModel_replaysDeterministically() throws Exception {
     Worker worker = testEnv.newWorker(TASK_QUEUE);
     worker.registerWorkflowImplementationTypes(ChatWorkflowImpl.class);
-
-    // Register a ChatModelActivityImpl backed by a mock model that returns a canned response
-    ChatModel mockModel = new StubChatModel("Hello from the model!");
-    worker.registerActivitiesImplementations(new ChatModelActivityImpl(mockModel));
+    worker.registerActivitiesImplementations(
+        new ChatModelActivityImpl(new StubChatModel("Hello from the model!")));
 
     testEnv.start();
 
@@ -64,16 +65,19 @@ void workflowWithChatModel_completesSuccessfully() {
 
     String result = workflow.chat("Hi");
     assertEquals("Hello from the model!", result);
+
+    // Capture history and replay — any non-determinism throws here
+    WorkflowExecutionHistory history =
+        client.fetchHistory(WorkflowStub.fromTyped(workflow).getExecution().getWorkflowId());
+    WorkflowReplayer.replayWorkflowExecution(history, ChatWorkflowImpl.class);
   }
 
   @Test
-  void workflowWithDeterministicTool_completesSuccessfully() {
+  void workflowWithTools_replaysDeterministically() throws Exception {
     Worker worker = testEnv.newWorker(TASK_QUEUE);
     worker.registerWorkflowImplementationTypes(ChatWithToolsWorkflowImpl.class);
-
-    // Model returns a simple response (no tool calls)
-    ChatModel mockModel = new StubChatModel("I used the tools!");
-    worker.registerActivitiesImplementations(new ChatModelActivityImpl(mockModel));
+    worker.registerActivitiesImplementations(
+        new ChatModelActivityImpl(new StubChatModel("I used the tools!")));
 
     testEnv.start();
 
@@ -83,6 +87,11 @@ void workflowWithDeterministicTool_completesSuccessfully() {
 
     String result = workflow.chat("Use tools");
     assertEquals("I used the tools!", result);
+
+    // Capture history and replay
+    WorkflowExecutionHistory history =
+        client.fetchHistory(WorkflowStub.fromTyped(workflow).getExecution().getWorkflowId());
+    WorkflowReplayer.replayWorkflowExecution(history, ChatWithToolsWorkflowImpl.class);
   }
 
   // --- Workflow interfaces and implementations ---