chore(ACI): add event_id column to group open period model (#104549)

We need to link between open periods and events on the frontend. Add an
event ID column to the group open period model to accomplish this. Make
the field nullable as we do not plan to backfill existing open periods.

Author: mifu67

migrations_lockfile.txt

@@ -31,7 +31,7 @@ releases: 0004_cleanup_failed_safe_deletes
 
 replays: 0006_add_bulk_delete_job
 
-sentry: 1011_update_oc_integration_cascade_to_null
+sentry: 1012_add_event_id_to_open_period
 
 social_auth: 0003_social_auth_json_field
 

src/sentry/migrations/1012_add_event_id_to_open_period.py

@@ -0,0 +1,33 @@
+# Generated by Django 5.2.8 on 2025-12-08 22:14
+
+from django.db import migrations, models
+
+from sentry.new_migrations.migrations import CheckedMigration
+
+
+class Migration(CheckedMigration):
+    # This flag is used to mark that a migration shouldn't be automatically run in production.
+    # This should only be used for operations where it's safe to run the migration after your
+    # code has deployed. So this should not be used for most operations that alter the schema
+    # of a table.
+    # Here are some things that make sense to mark as post deployment:
+    # - Large data migrations. Typically we want these to be run manually so that they can be
+    #   monitored and not block the deploy for a long period of time while they run.
+    # - Adding indexes to large tables. Since this can take a long time, we'd generally prefer to
+    #   run this outside deployments so that we don't block them. Note that while adding an index
+    #   is a schema change, it's completely safe to run the operation after the code has deployed.
+    # Once deployed, run these manually via: https://develop.sentry.dev/database-migrations/#migration-deployment
+
+    is_post_deployment = False
+
+    dependencies = [
+        ("sentry", "1011_update_oc_integration_cascade_to_null"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="groupopenperiod",
+            name="event_id",
+            field=models.CharField(max_length=32, null=True),
+        ),
+    ]

src/sentry/models/groupopenperiod.py

@@ -58,6 +58,7 @@ class GroupOpenPeriod(DefaultFieldsModel):
     date_ended = models.DateTimeField(null=True)
 
     data = models.JSONField(default=dict)
+    event_id = models.CharField(max_length=32, null=True)
 
     class Meta:
         app_label = "sentry"