fix: clone history events to prevent mutation

apps/tests/aws-runtime/test/test-service.ts

@@ -1566,3 +1566,37 @@ export const getPresigned = command("getPresigned", {}, async () => {
 
   return { key, putUrl, getUrl, headUrl, deleteUrl };
 });
+
+const mutateEntity = entity("mutate", {
+  partition: ["pk"],
+  attributes: {
+    pk: z.string(),
+    obj: z.object({
+      key: z.string(),
+    }),
+  },
+});
+
+// see: https://github.com/functionless/eventual/pull/479
+export const mutateEvents = workflow("mutateEvents", async () => {
+  await mutateEntity.put({
+    pk: "pk",
+    obj: {
+      key: "v1",
+    },
+  });
+
+  let e = await mutateEntity.get({
+    pk: "pk",
+  });
+
+  e!.obj.key = "v2";
+
+  await mutateEntity.put(e!);
+
+  e = await mutateEntity.get({
+    pk: "pk",
+  });
+
+  return e!.obj.key;
+});

apps/tests/aws-runtime/test/tester.test.ts

@@ -21,6 +21,7 @@ import {
   eventDrivenWorkflow,
   failedWorkflow,
   heartbeatWorkflow,
+  mutateEvents,
   parentWorkflow,
   queueWorkflow,
   SocketMessage,
@@ -53,6 +54,8 @@ eventualRuntimeTestHarness(
 
     testCompletion("sleep", workflow3, "done!");
 
+    testCompletion("mutate events", mutateEvents, "v2");
+
     testCompletion("parallel", workflow4, [
       { status: "fulfilled", value: ["hello sam", "hello chris", "hello sam"] },
       { status: "fulfilled", value: ["HELLO SAM", "HELLO CHRIS", "HELLO SAM"] },

packages/@eventual/core-runtime/src/deep-clone.ts

@@ -0,0 +1,4 @@
+export function deepClone<T>(item: T): T {
+  // TODO: more efficient deep clone
+  return item === undefined ? item : JSON.parse(JSON.stringify(item));
+}

packages/@eventual/core-runtime/src/providers/executor-provider.ts

@@ -54,7 +54,7 @@ export class RemoteExecutorProvider<Context = undefined>
     executor: WorkflowExecutor<any, any, any>
   ): Promise<{ storedBytes: number }> {
     // provides a shallow copy of the history events.
-    const historyEvents = executor.history.slice(0);
+    const historyEvents = executor.historyCloned.slice(0);
     historyEvents.push(...newHistoryEvents);
     const { bytes } = await this.props.executionHistoryStateStore.updateHistory(
       {

packages/@eventual/core-runtime/src/workflow/workflow-executor.ts

@@ -50,6 +50,7 @@ import {
   type UnresolvedEventualDefinition,
 } from "./eventual-definition.js";
 import { formatExecutionId } from "./execution.js";
+import { deepClone } from "../deep-clone.js";
 
 /**
  * Put the resolve method on the promise, but don't expose it.
@@ -206,13 +207,17 @@ export class WorkflowExecutor<Input, Output, Context = undefined> {
     ) => void;
   } = {};
 
+  // clone the history so it cannot be modified by the user
+  public historyCloned: HistoryStateEvent[];
+
   constructor(
     private workflow: Workflow<any, Input, Output>,
     public history: HistoryStateEvent[],
     // TODO: properties used in the workflow should be encoded in the history to keep them constant between runs
     private propertyRetriever: PropertyRetriever,
     private eventualFactory: EventualFactory = createDefaultEventualFactory()
   ) {
+    this.historyCloned = deepClone(history);
     this.nextSeq = 0;
     this.expected = iterator(history, isCallEvent);
     this.events = iterator(history, isCompletionEvent);