fix(seer): Deduplicate night shift cron runs

migrations_lockfile.txt

@@ -31,7 +31,7 @@ releases: 0004_cleanup_failed_safe_deletes
 
 replays: 0001_squashed_0007_organizationmember_replay_access
 
-seer: 0029_add_agent_write_grant
+seer: 0030_add_night_shift_run_schedule_id
 
 sentry: 1146_add_gcp_service_account
 

src/sentry/seer/migrations/0030_add_night_shift_run_schedule_id.py

@@ -0,0 +1,47 @@
+# Generated by Django 5.2.14 on 2026-07-24 22:38
+
+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 = [
+        ("seer", "0029_add_agent_write_grant"),
+        ("sentry", "1146_add_gcp_service_account"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="seernightshiftrun",
+            name="schedule_id",
+            field=models.CharField(max_length=256, null=True),
+        ),
+        migrations.AddField(
+            model_name="seernightshiftrun",
+            name="date_completed",
+            field=models.DateTimeField(null=True),
+        ),
+        migrations.AddConstraint(
+            model_name="seernightshiftrun",
+            constraint=models.UniqueConstraint(
+                condition=models.Q(("schedule_id__isnull", False)),
+                fields=("organization", "workflow_config", "schedule_id"),
+                name="seer_nightshiftrun_unique_org_config_schedule",
+            ),
+        ),
+    ]

src/sentry/seer/models/night_shift.py

@@ -10,9 +10,10 @@
 
 @cell_silo_model
 class SeerNightShiftRun(DefaultFieldsModel):
-    """
-    Records each night shift invocation for an organization.
-    One row is created per org each time run_night_shift_for_org executes.
+    """Records each night shift invocation for an organization.
+
+    Cron invocations create one row per organization, workflow config, and
+    schedule window. Manual invocations create one row per execution.
     """
 
     __relocation_scope__ = RelocationScope.Excluded
@@ -21,6 +22,10 @@ class SeerNightShiftRun(DefaultFieldsModel):
     workflow_config = FlexibleForeignKey(
         "seer.SeerWorkflowConfig", on_delete=models.SET_NULL, null=True
     )
+    # Cron-derived schedule window (currently YYYY-MM-DDTHH:MM); nullable for
+    # manual and historical runs, with standard capacity for future formats.
+    schedule_id = models.CharField(max_length=256, null=True)
+    date_completed = models.DateTimeField(null=True)
     extras = models.JSONField(db_default={}, default=dict)
 
     class Meta:
@@ -31,6 +36,13 @@ class Meta:
             models.Index(fields=["date_added"]),
             models.Index(fields=["workflow_config", "date_added"]),
         ]
+        constraints = [
+            models.UniqueConstraint(
+                fields=["organization", "workflow_config", "schedule_id"],
+                condition=models.Q(schedule_id__isnull=False),
+                name="seer_nightshiftrun_unique_org_config_schedule",
+            )
+        ]
 
     __repr__ = sane_repr("organization_id", "workflow_config_id", "date_added")