First pass at semaphore

util/Migrator/DbScripts/2025-12-30_02_PopulateDefaultCollectionSemaphore.sql

@@ -0,0 +1,29 @@
+-- Populate DefaultCollectionSemaphore from existing Type=1 (DefaultUserCollection) collections
+-- This migration is idempotent and can be run multiple times safely
+INSERT INTO [dbo].[DefaultCollectionSemaphore]
+(
+    [OrganizationId],
+    [OrganizationUserId],
+    [CreationDate]
+)
+SELECT DISTINCT
+    c.[OrganizationId],
+    cu.[OrganizationUserId],
+    c.[CreationDate]
+FROM
+    [dbo].[Collection] c
+INNER JOIN
+    [dbo].[CollectionUser] cu ON c.[Id] = cu.[CollectionId]
+WHERE
+    c.[Type] = 1 -- CollectionType.DefaultUserCollection
+    AND NOT EXISTS
+    (
+        SELECT
+            1
+        FROM
+            [dbo].[DefaultCollectionSemaphore] dcs
+        WHERE
+            dcs.[OrganizationId] = c.[OrganizationId]
+            AND dcs.[OrganizationUserId] = cu.[OrganizationUserId]
+    );
+GO