Fix local pricelist uniqueness and preserve config project on update

internal/localdb/migrations.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"strings"
 	"time"
 
 	"github.com/google/uuid"
@@ -47,6 +48,11 @@ var localMigrations = []localMigration{
 		name: "Attach existing configurations to latest local pricelist and recalc usage",
 		run:  backfillConfigurationPricelists,
 	},
+	{
+		id:   "2026_02_06_pricelist_index_fix",
+		name: "Use unique server_id for local pricelists and allow duplicate versions",
+		run:  fixLocalPricelistIndexes,
+	},
 }
 
 func runLocalMigrations(db *gorm.DB) error {
@@ -237,3 +243,52 @@ func chooseNonZeroTime(candidate time.Time, fallback time.Time) time.Time {
 	}
 	return candidate
 }
+
+func fixLocalPricelistIndexes(tx *gorm.DB) error {
+	type indexRow struct {
+		Name   string `gorm:"column:name"`
+		Unique int    `gorm:"column:unique"`
+	}
+	var indexes []indexRow
+	if err := tx.Raw("PRAGMA index_list('local_pricelists')").Scan(&indexes).Error; err != nil {
+		return fmt.Errorf("list local_pricelists indexes: %w", err)
+	}
+
+	for _, idx := range indexes {
+		if idx.Unique == 0 {
+			continue
+		}
+
+		type indexInfoRow struct {
+			Name string `gorm:"column:name"`
+		}
+		var info []indexInfoRow
+		if err := tx.Raw(fmt.Sprintf("PRAGMA index_info('%s')", strings.ReplaceAll(idx.Name, "'", "''"))).Scan(&info).Error; err != nil {
+			return fmt.Errorf("load index info for %s: %w", idx.Name, err)
+		}
+		if len(info) != 1 || info[0].Name != "version" {
+			continue
+		}
+
+		quoted := strings.ReplaceAll(idx.Name, `"`, `""`)
+		if err := tx.Exec(fmt.Sprintf(`DROP INDEX IF EXISTS "%s"`, quoted)).Error; err != nil {
+			return fmt.Errorf("drop unique version index %s: %w", idx.Name, err)
+		}
+	}
+
+	if err := tx.Exec(`
+		CREATE UNIQUE INDEX IF NOT EXISTS idx_local_pricelists_server_id
+		ON local_pricelists(server_id)
+	`).Error; err != nil {
+		return fmt.Errorf("ensure unique index local_pricelists(server_id): %w", err)
+	}
+
+	if err := tx.Exec(`
+		CREATE INDEX IF NOT EXISTS idx_local_pricelists_version
+		ON local_pricelists(version)
+	`).Error; err != nil {
+		return fmt.Errorf("ensure index local_pricelists(version): %w", err)
+	}
+
+	return nil
+}