fix: ensure alerts table columns exist

- Add idempotent migration to ensure severity, notification_sent, etc. columns exist
- Fixes production issue where migration was marked as run but columns weren't created
- Uses IF NOT EXISTS to safely add missing columns without errors
- Includes all columns and indexes from ExtendAlertsForChecks migration

priv/repo/migrations/20260305184122_ensure_alerts_columns_exist.exs

@@ -0,0 +1,70 @@
+defmodule Towerops.Repo.Migrations.EnsureAlertsColumnsExist do
+  use Ecto.Migration
+
+  def up do
+    # Ensure columns from ExtendAlertsForChecks migration exist
+    # This fixes cases where the migration was marked as run but columns weren't created
+    execute """
+    ALTER TABLE alerts
+    ADD COLUMN IF NOT EXISTS severity INTEGER DEFAULT 2
+    """
+
+    execute """
+    ALTER TABLE alerts
+    ADD COLUMN IF NOT EXISTS notification_sent BOOLEAN DEFAULT false
+    """
+
+    execute """
+    ALTER TABLE alerts
+    ADD COLUMN IF NOT EXISTS notification_sent_at TIMESTAMP
+    """
+
+    execute """
+    ALTER TABLE alerts
+    ADD COLUMN IF NOT EXISTS output TEXT
+    """
+
+    execute """
+    ALTER TABLE alerts
+    ADD COLUMN IF NOT EXISTS check_id UUID
+    """
+
+    # Create indexes if they don't exist
+    execute """
+    CREATE INDEX IF NOT EXISTS alerts_check_id_index ON alerts (check_id)
+    """
+
+    execute """
+    CREATE INDEX IF NOT EXISTS alerts_severity_index ON alerts (severity)
+    """
+
+    execute """
+    CREATE INDEX IF NOT EXISTS alerts_notification_sent_index ON alerts (notification_sent)
+    """
+
+    # Add foreign key constraint if it doesn't exist
+    execute """
+    DO $$
+    BEGIN
+      IF NOT EXISTS (
+        SELECT 1 FROM pg_constraint WHERE conname = 'alerts_check_id_fkey'
+      ) THEN
+        ALTER TABLE alerts
+        ADD CONSTRAINT alerts_check_id_fkey
+        FOREIGN KEY (check_id) REFERENCES checks(id) ON DELETE CASCADE;
+      END IF;
+    END $$;
+    """
+
+    # Make device_id nullable if it isn't already
+    execute """
+    ALTER TABLE alerts
+    ALTER COLUMN device_id DROP NOT NULL
+    """
+  end
+
+  def down do
+    # Don't remove columns on rollback - data safety
+    :ok
+  end
+end