fix(server): session updated at (#13099)

fix AI-325

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

## Summary by CodeRabbit

* **Chores**
* Improved database handling for session update times to ensure more
accurate tracking of session activity.
* Enhanced migration process to better manage and update session
metadata.

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

packages/backend/server/migrations/20250625070609_ai_session_updated_at/migration.sql

@@ -1,5 +1,9 @@
 -- AlterTable
-ALTER TABLE "ai_sessions_metadata" ADD COLUMN     "updated_at" TIMESTAMPTZ(3) NOT NULL DEFAULT CURRENT_TIMESTAMP;
+ALTER TABLE ai_sessions_metadata ADD COLUMN updated_at TIMESTAMPTZ(3);
+
+UPDATE ai_sessions_metadata SET updated_at = created_at;
+
+ALTER TABLE ai_sessions_metadata ALTER COLUMN updated_at SET NOT NULL, ALTER COLUMN updated_at SET DEFAULT CURRENT_TIMESTAMP;
 
 -- DropIndex
 DROP INDEX IF EXISTS "ai_session_unique_doc_session_idx";

packages/backend/server/src/data/migrations/1751966744168-correct-session-update-time.ts

@@ -0,0 +1,34 @@
+import { PrismaClient } from '@prisma/client';
+
+type SessionTime = {
+  sessionId: string;
+  _max: {
+    createdAt: Date;
+  };
+};
+
+export class CorrectSessionUpdateTime1751966744168 {
+  // do the migration
+  static async up(db: PrismaClient) {
+    const sessionTime = await db.aiSessionMessage.groupBy({
+      by: ['sessionId'],
+      _max: {
+        createdAt: true,
+      },
+    });
+
+    await Promise.all(
+      sessionTime
+        .filter((s): s is SessionTime => !!s._max.createdAt)
+        .map(s =>
+          db.aiSession.update({
+            where: { id: s.sessionId },
+            data: { updatedAt: s._max.createdAt },
+          })
+        )
+    );
+  }
+
+  // revert the migration
+  static async down(_db: PrismaClient) {}
+}

packages/backend/server/src/data/migrations/index.ts

@@ -6,3 +6,4 @@ export * from './1732861452428-migrate-invite-status';
 export * from './1733125339942-universal-subscription';
 export * from './1738590347632-feature-redundant';
 export * from './1745211351719-create-indexer-tables';
+export * from './1751966744168-correct-session-update-time';