feat(dashboards): loosen unique title db constraint on dashboards (#104046)

This updates the unique title constraint to only apply for non-prebuilt
dashboards. This allows us to built prebuilt ones with the same title as
an existing user created on. The UI will distinguish the two by the
author field

Author: DominikB2014

migrations_lockfile.txt

@@ -31,7 +31,7 @@ releases: 0004_cleanup_failed_safe_deletes
 
 replays: 0006_add_bulk_delete_job
 
-sentry: 1007_cleanup_failed_safe_deletes
+sentry: 1008_loosen_unique_title_contraint
 
 social_auth: 0003_social_auth_json_field
 

src/sentry/migrations/1008_loosen_unique_title_contraint.py

@@ -0,0 +1,40 @@
+# Generated by Django 5.2.8 on 2025-11-26 15:37
+
+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", "1007_cleanup_failed_safe_deletes"),
+    ]
+
+    operations = [
+        migrations.AlterUniqueTogether(
+            name="dashboard",
+            unique_together=set(),
+        ),
+        migrations.AddConstraint(
+            model_name="dashboard",
+            constraint=models.UniqueConstraint(
+                condition=models.Q(("prebuilt_id__isnull", True)),
+                fields=("organization", "title"),
+                name="sentry_dashboard_organization_title_uniq",
+            ),
+        ),
+    ]

src/sentry/models/dashboard.py

@@ -237,8 +237,13 @@ class Dashboard(Model):
     class Meta:
         app_label = "sentry"
         db_table = "sentry_dashboard"
-        unique_together = (("organization", "title"),)
         constraints = [
+            # User-created dashboards must have unique titles within an organization, but a prebuilt one can exist with the same title
+            UniqueConstraint(
+                fields=["organization", "title"],
+                condition=Q(prebuilt_id__isnull=True),
+                name="sentry_dashboard_organization_title_uniq",
+            ),
             UniqueConstraint(
                 fields=["organization", "prebuilt_id"],
                 condition=Q(prebuilt_id__isnull=False),