First pass at semaphore

util/Migrator/DbScripts/2025-12-30_00_DefaultCollectionSemaphore.sql

@@ -0,0 +1,23 @@
+-- Create DefaultCollectionSemaphore table
+-- Cascade behavior: Organization -> OrganizationUser (CASCADE) -> DefaultCollectionSemaphore (CASCADE)
+-- OrganizationId FK has NO ACTION to avoid competing cascade paths
+IF OBJECT_ID('[dbo].[DefaultCollectionSemaphore]') IS NULL
+BEGIN
+    CREATE TABLE [dbo].[DefaultCollectionSemaphore]
+    (
+        [OrganizationId] UNIQUEIDENTIFIER NOT NULL,
+        [OrganizationUserId] UNIQUEIDENTIFIER NOT NULL,
+        [CreationDate] DATETIME2(7) NOT NULL,
+        CONSTRAINT [PK_DefaultCollectionSemaphore] PRIMARY KEY CLUSTERED
+        (
+            [OrganizationId] ASC,
+            [OrganizationUserId] ASC
+        ),
+        CONSTRAINT [FK_DefaultCollectionSemaphore_Organization] FOREIGN KEY ([OrganizationId])
+            REFERENCES [dbo].[Organization] ([Id]), -- NO ACTION to avoid competing cascades
+        CONSTRAINT [FK_DefaultCollectionSemaphore_OrganizationUser] FOREIGN KEY ([OrganizationUserId])
+            REFERENCES [dbo].[OrganizationUser] ([Id])
+            ON DELETE CASCADE -- Cascades from OrganizationUser deletion
+    );
+END
+GO

util/Migrator/DbScripts/2025-12-30_01_Collection_UpsertDefaultCollections.sql

@@ -0,0 +1,83 @@
+CREATE OR ALTER PROCEDURE [dbo].[Collection_UpsertDefaultCollections]
+    @OrganizationId UNIQUEIDENTIFIER,
+    @DefaultCollectionName VARCHAR(MAX),
+    @OrganizationUserIdsJson NVARCHAR(MAX)
+AS
+BEGIN
+    SET NOCOUNT ON
+
+    -- Parse JSON once into table variable with pre-generated collection IDs
+    DECLARE @OrganizationUserIds TABLE
+    (
+        [OrganizationUserId] UNIQUEIDENTIFIER,
+        [CollectionId] UNIQUEIDENTIFIER
+    );
+
+    INSERT INTO @OrganizationUserIds
+    (
+        [OrganizationUserId],
+        [CollectionId]
+    )
+    SELECT
+        CAST([value] AS UNIQUEIDENTIFIER),
+        NEWID()
+    FROM
+        OPENJSON(@OrganizationUserIdsJson);
+
+    -- Insert semaphore entries first to obtain the "lock"
+    INSERT INTO [dbo].[DefaultCollectionSemaphore]
+    (
+        [OrganizationId],
+        [OrganizationUserId],
+        [CreationDate]
+    )
+    SELECT
+        @OrganizationId,
+        ou.[OrganizationUserId],
+        GETUTCDATE()
+    FROM
+        @OrganizationUserIds ou;
+
+    -- Insert collections for users who obtained semaphore entries
+    INSERT INTO [dbo].[Collection]
+    (
+        [Id],
+        [OrganizationId],
+        [Name],
+        [CreationDate],
+        [RevisionDate],
+        [Type],
+        [ExternalId],
+        [DefaultUserCollectionEmail]
+    )
+    SELECT
+        ou.[CollectionId],
+        @OrganizationId,
+        @DefaultCollectionName,
+        GETUTCDATE(),
+        GETUTCDATE(),
+        1, -- CollectionType.DefaultUserCollection
+        NULL,
+        NULL
+    FROM
+        @OrganizationUserIds ou;
+
+    -- Insert collection user mappings
+    INSERT INTO [dbo].[CollectionUser]
+    (
+        [CollectionId],
+        [OrganizationUserId],
+        [ReadOnly],
+        [HidePasswords],
+        [Manage]
+    )
+    SELECT
+        ou.[CollectionId],
+        ou.[OrganizationUserId],
+        0, -- ReadOnly = false
+        0, -- HidePasswords = false
+        1  -- Manage = true
+    FROM
+        @OrganizationUserIds ou;
+END
+GO

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