diff --git a/CHANGELOG.md b/CHANGELOG.md
index 845f0d4..4c90183 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,9 @@
 
 ### Fixes
 
+- Handle external event names such as `constructor` and `__proto__` without failing the
+  orchestration. Case-insensitive matching, per-name FIFO ordering, and unprocessed-event
+  carryover through continue-as-new are preserved.
 - Make the Durable Task activity execution span active while user activity code runs, so
   spans created by activities inherit the correct parent across awaits and concurrent executions.
 - Preserve received structured failure `properties` in task errors, retry callbacks, client
diff --git a/packages/durabletask-js/src/worker/runtime-orchestration-context.ts b/packages/durabletask-js/src/worker/runtime-orchestration-context.ts
index 8a89311..95ae138 100644
--- a/packages/durabletask-js/src/worker/runtime-orchestration-context.ts
+++ b/packages/durabletask-js/src/worker/runtime-orchestration-context.ts
@@ -80,8 +80,9 @@ export class RuntimeOrchestrationContext extends OrchestrationContext {
     this._version = "";
     this._parent = undefined;
     this._completionStatus = undefined;
-    this._receivedEvents = {};
-    this._pendingEvents = {};
+    // Event names must not resolve inherited object properties.
+    this._receivedEvents = Object.create(null);
+    this._pendingEvents = Object.create(null);
     this._newInput = undefined;
     this._saveEvents = false;
     this._newVersion = undefined;
diff --git a/packages/durabletask-js/test/external-event-routing.spec.ts b/packages/durabletask-js/test/external-event-routing.spec.ts
new file mode 100644
index 0000000..772322e
--- /dev/null
+++ b/packages/durabletask-js/test/external-event-routing.spec.ts
@@ -0,0 +1,181 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+import {
+  InMemoryOrchestrationBackend,
+  TestOrchestrationClient,
+  TestOrchestrationWorker,
+  OrchestrationContext,
+  OrchestrationStatus,
+  TOrchestrator,
+} from "../src";
+
+describe("External event name routing", () => {
+  let backend: InMemoryOrchestrationBackend;
+  let client: TestOrchestrationClient;
+  let worker: TestOrchestrationWorker;
+
+  beforeEach(() => {
+    backend = new InMemoryOrchestrationBackend();
+    client = new TestOrchestrationClient(backend);
+    worker = new TestOrchestrationWorker(backend);
+  });
+
+  afterEach(async () => {
+    try {
+      await worker.stop();
+    } finally {
+      await client.stop();
+      backend.reset();
+    }
+  });
+
+  async function expectRunning(instanceId: string): Promise<void> {
+    const state = await client.waitForOrchestrationStart(instanceId, true, 5);
+    expect(state?.failureDetails).toBeUndefined();
+    expect(state?.runtimeStatus).toBe(OrchestrationStatus.RUNNING);
+  }
+
+  async function raiseAndWaitForCommit(instanceId: string, name: string, payload: unknown): Promise<void> {
+    await client.raiseOrchestrationEvent(instanceId, name, payload);
+    await backend.waitForState(
+      instanceId,
+      (instance) =>
+        instance.history.some(
+          (event) =>
+            event.getEventraised()?.getName() === name &&
+            event.getEventraised()?.getInput()?.getValue() === JSON.stringify(payload),
+        ),
+      5000,
+    );
+    const state = await client.getOrchestrationState(instanceId);
+    expect(state?.failureDetails).toBeUndefined();
+  }
+
+  const eventNames = [
+    { waitName: "constructor", raiseName: "Constructor" },
+    { waitName: "Constructor", raiseName: "constructor" },
+    { waitName: "__proto__", raiseName: "__PROTO__" },
+    { waitName: "Approval", raiseName: "APPROVAL" },
+    { waitName: "toString", raiseName: "TOSTRING" },
+  ];
+
+  it.each(eventNames)("delivers $waitName when the listener is registered first", async ({ waitName, raiseName }) => {
+    const orchestrator: TOrchestrator = async function* (ctx: OrchestrationContext): any {
+      return yield ctx.waitForExternalEvent(waitName);
+    };
+    worker.addOrchestrator(orchestrator);
+    await worker.start();
+
+    const id = await client.scheduleNewOrchestration(orchestrator);
+    await expectRunning(id);
+    const payload = { event: waitName, value: 42 };
+    await raiseAndWaitForCommit(id, raiseName, payload);
+
+    const state = await client.waitForOrchestrationCompletion(id, true, 5);
+    expect(state?.runtimeStatus).toBe(OrchestrationStatus.COMPLETED);
+    expect(state?.serializedOutput).toBe(JSON.stringify(payload));
+    expect(state?.failureDetails).toBeUndefined();
+  });
+
+  it.each(eventNames)("buffers $waitName before its listener is registered", async ({ waitName, raiseName }) => {
+    const orchestrator: TOrchestrator = async function* (ctx: OrchestrationContext): any {
+      yield ctx.waitForExternalEvent("ready");
+      return yield ctx.waitForExternalEvent(waitName);
+    };
+    worker.addOrchestrator(orchestrator);
+    await worker.start();
+
+    const id = await client.scheduleNewOrchestration(orchestrator);
+    await expectRunning(id);
+    const payload = { event: waitName, value: 42 };
+    await raiseAndWaitForCommit(id, raiseName, payload);
+    expect((await client.getOrchestrationState(id))?.runtimeStatus).toBe(OrchestrationStatus.RUNNING);
+    await client.raiseOrchestrationEvent(id, "ready");
+
+    const state = await client.waitForOrchestrationCompletion(id, true, 5);
+    expect(state?.runtimeStatus).toBe(OrchestrationStatus.COMPLETED);
+    expect(state?.serializedOutput).toBe(JSON.stringify(payload));
+    expect(state?.failureDetails).toBeUndefined();
+    const events = backend.getInstance(id)?.history.filter((event) => event.hasEventraised());
+    expect(events?.map((event) => event.getEventraised()?.getName())).toEqual([raiseName, "ready"]);
+  });
+
+  describe.each([false, true])("FIFO with buffered=%s", (buffered) => {
+    it.each(["constructor", "__proto__", "approval"])("preserves falsy payloads and ordering for %s", async (name) => {
+      const orchestrator: TOrchestrator = async function* (ctx: OrchestrationContext): any {
+        if (buffered) {
+          yield ctx.waitForExternalEvent("ready");
+        }
+        const first = yield ctx.waitForExternalEvent(name);
+        const second = yield ctx.waitForExternalEvent(name);
+        return [first, second];
+      };
+      worker.addOrchestrator(orchestrator);
+      await worker.start();
+
+      const id = await client.scheduleNewOrchestration(orchestrator);
+      await expectRunning(id);
+      await raiseAndWaitForCommit(id, name.toUpperCase(), false);
+      expect((await client.getOrchestrationState(id))?.runtimeStatus).toBe(OrchestrationStatus.RUNNING);
+      await raiseAndWaitForCommit(id, name, 0);
+      if (buffered) {
+        expect((await client.getOrchestrationState(id))?.runtimeStatus).toBe(OrchestrationStatus.RUNNING);
+        await client.raiseOrchestrationEvent(id, "ready");
+      }
+
+      const state = await client.waitForOrchestrationCompletion(id, true, 5);
+      expect(state?.runtimeStatus).toBe(OrchestrationStatus.COMPLETED);
+      expect(state?.serializedOutput).toBe("[false,0]");
+      expect(state?.failureDetails).toBeUndefined();
+    });
+  });
+
+  it.each(["constructor", "__proto__", "approval"])(
+    "carries buffered %s events through continue-as-new and consumes each once during replay",
+    async (name) => {
+      const orchestrator: TOrchestrator = async function* (
+        ctx: OrchestrationContext,
+        input: { iteration: number },
+      ): any {
+        if (input.iteration === 1) {
+          yield ctx.waitForExternalEvent("continue");
+          ctx.continueAsNew({ iteration: 2 }, true);
+          return;
+        }
+        const first = yield ctx.waitForExternalEvent(name);
+        const second = yield ctx.waitForExternalEvent(name);
+        const third = yield ctx.waitForExternalEvent(name);
+        return [first, second, third];
+      };
+      worker.addOrchestrator(orchestrator);
+      await worker.start();
+
+      const id = await client.scheduleNewOrchestration(orchestrator, { iteration: 1 });
+      await expectRunning(id);
+      const firstExecutionId = backend.getInstance(id)?.executionId;
+      await raiseAndWaitForCommit(id, name.toUpperCase(), false);
+      await raiseAndWaitForCommit(id, name, 0);
+      await client.raiseOrchestrationEvent(id, "continue");
+      await backend.waitForState(
+        id,
+        (instance) =>
+          instance.executionId !== firstExecutionId &&
+          instance.history.filter((event) => event.hasEventraised()).length === 2,
+        5000,
+      );
+
+      await expectRunning(id);
+      const carryover = backend.getInstance(id)?.history.filter((event) => event.hasEventraised());
+      expect(carryover?.map((event) => event.getEventraised()?.getName())).toEqual([name, name]);
+      expect(carryover?.map((event) => event.getEventraised()?.getInput()?.getValue())).toEqual(["false", "0"]);
+      await raiseAndWaitForCommit(id, name.toUpperCase(), "fresh");
+
+      const state = await client.waitForOrchestrationCompletion(id, true, 5);
+      expect(state?.runtimeStatus).toBe(OrchestrationStatus.COMPLETED);
+      expect(state?.serializedOutput).toBe('[false,0,"fresh"]');
+      expect(state?.failureDetails).toBeUndefined();
+      expect(backend.getInstance(id)?.history.filter((event) => event.hasEventraised())).toHaveLength(3);
+    },
+  );
+});