fix(sqlite): tag per-migration database backups with version and prevent collisions

server/lib/backupFileName.ts

@@ -26,3 +26,26 @@ export function formatBackupTimestamp(date: Date = new Date()): string {
 
     return `${datePart}_${timePart}`;
 }
+
+/**
+ * Builds the full database backup file name, including timestamp and optional version tag.
+ *
+ * When a migration version is provided, the filename includes `_v<version>`,
+ * preventing collisions between multiple migrations running in the same second and making it easy
+ * to identify the migration state contained in the backup.
+ *
+ * @param version Optional migration version being run.
+ * @param date The moment the backup is being taken. Defaults to now.
+ * @returns A filename of the form `db_YYYY-MM-DD_HH-MM-SS_v<version>.sqlite` or `db_YYYY-MM-DD_HH-MM-SS.sqlite`.
+ */
+export function formatBackupFileName(
+    version?: string,
+    date: Date = new Date()
+): string {
+    const timestamp = formatBackupTimestamp(date);
+    if (version) {
+        const versionTag = version.startsWith("v") ? version : `v${version}`;
+        return `db_${timestamp}_${versionTag}.sqlite`;
+    }
+    return `db_${timestamp}.sqlite`;
+}