fix: history may duplicate on concurrency (#14487)

#### PR Dependency Tree


* **PR #14487** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Bug Fixes**
* Enhanced history record creation to prevent duplicate entries in
concurrent scenarios.

* **Tests**
  * Added validation for idempotent history record creation.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/models/__tests__/history.spec.ts

@@ -74,6 +74,27 @@ test('should create a history record', async t => {
   });
 });
 
+test('should not fail on duplicated history record', async t => {
+  const snapshot = {
+    spaceId: workspace.id,
+    docId: randomUUID(),
+    blob: Uint8Array.from([1, 2, 3]),
+    timestamp: Date.now(),
+    editorId: user.id,
+  };
+
+  const created1 = await t.context.history.create(snapshot, 1000);
+  const created2 = await t.context.history.create(snapshot, 1000);
+  t.deepEqual(created1.timestamp, snapshot.timestamp);
+  t.deepEqual(created2.timestamp, snapshot.timestamp);
+
+  const histories = await t.context.history.findMany(
+    snapshot.spaceId,
+    snapshot.docId
+  );
+  t.is(histories.length, 1);
+});
+
 test('should return null when history timestamp not match', async t => {
   const snapshot = {
     spaceId: workspace.id,