Honor optional sort_order on module create under a course.

Accept sort_order in CreateModuleInput, shift siblings when set, and default to max+1 when omitted.

Co-authored-by: Cursor <cursoragent@cursor.com>

db/query/lms_modules.sql

@@ -1,17 +1,18 @@
 -- name: CreateModule :one
 INSERT INTO modules (program_id, course_id, name, description, icon, sort_order)
 SELECT
-    $1,
+    sqlc.arg('program_id'),
-    $2,
+    sqlc.arg('course_id'),
-    $3,
+    sqlc.arg('name'),
-    $4,
+    sqlc.arg('description'),
-    $5,
+    sqlc.arg('icon'),
-    coalesce((
+    COALESCE(sqlc.narg('sort_order')::int,
+        COALESCE((
             SELECT
                 max(m.sort_order)
             FROM modules m
             WHERE
-            m.course_id = $2), 0) + 1
+                m.course_id = sqlc.arg('course_id')), 0) + 1)
 RETURNING
     *;
 

gen/db/lms_modules.sql.go

@@ -19,12 +19,13 @@ SELECT
     $3,
     $4,
     $5,
-    coalesce((
+    COALESCE($6::int,
+        COALESCE((
             SELECT
                 max(m.sort_order)
             FROM modules m
             WHERE
-            m.course_id = $2), 0) + 1
+                m.course_id = $2), 0) + 1)
 RETURNING
     id, program_id, course_id, name, description, icon, created_at, updated_at, sort_order
 `
@@ -35,6 +36,7 @@ type CreateModuleParams struct {
 	Name        string      `json:"name"`
 	Description pgtype.Text `json:"description"`
 	Icon        pgtype.Text `json:"icon"`
+	SortOrder   pgtype.Int4 `json:"sort_order"`
 }
 
 func (q *Queries) CreateModule(ctx context.Context, arg CreateModuleParams) (Module, error) {
@@ -44,6 +46,7 @@ func (q *Queries) CreateModule(ctx context.Context, arg CreateModuleParams) (Mod
 		arg.Name,
 		arg.Description,
 		arg.Icon,
+		arg.SortOrder,
 	)
 	var i Module
 	err := row.Scan(

internal/domain/module.go

@@ -21,6 +21,8 @@ type CreateModuleInput struct {
 	Name        string  `json:"name" validate:"required"`
 	Description *string `json:"description,omitempty"`
 	Icon        *string `json:"icon,omitempty"`
+	// SortOrder within the course when set; omit to append after current max within course_id (uniqueness is per-course).
+	SortOrder *int `json:"sort_order,omitempty" validate:"omitempty,min=0"`
 }
 
 type UpdateModuleInput struct {

internal/repository/lms_modules.go

@@ -30,12 +30,43 @@ func moduleToDomain(m dbgen.Module) domain.Module {
 }
 
 func (s *Store) CreateModule(ctx context.Context, programID, courseID int64, input domain.CreateModuleInput) (domain.Module, error) {
+	if input.SortOrder != nil {
+		q, tx, err := s.BeginTx(ctx)
+		if err != nil {
+			return domain.Module{}, err
+		}
+		defer func() { _ = tx.Rollback(ctx) }()
+		target := int32(*input.SortOrder)
+		if _, err := tx.Exec(ctx,
+			`UPDATE modules SET sort_order = sort_order + 1 WHERE course_id = $1 AND sort_order >= $2`,
+			courseID, target,
+		); err != nil {
+			return domain.Module{}, err
+		}
+		m, err := q.CreateModule(ctx, dbgen.CreateModuleParams{
+			ProgramID:   programID,
+			CourseID:    courseID,
+			Name:        input.Name,
+			Description: toPgText(input.Description),
+			Icon:        toPgText(input.Icon),
+			SortOrder:   pgtype.Int4{Int32: target, Valid: true},
+		})
+		if err != nil {
+			return domain.Module{}, err
+		}
+		if err := tx.Commit(ctx); err != nil {
+			return domain.Module{}, err
+		}
+		return moduleToDomain(m), nil
+	}
+
 	m, err := s.queries.CreateModule(ctx, dbgen.CreateModuleParams{
 		ProgramID:   programID,
 		CourseID:    courseID,
 		Name:        input.Name,
 		Description: toPgText(input.Description),
 		Icon:        toPgText(input.Icon),
+		SortOrder:   pgtype.Int4{Valid: false},
 	})
 	if err != nil {
 		return domain.Module{}, err