diff --git a/prisma/migrations/20260106112014_relax_unique_constraint_on_pairs/migration.sql b/prisma/migrations/20260106112014_relax_unique_constraint_on_pairs/migration.sql
new file mode 100644
index 0000000..c16b32f
--- /dev/null
+++ b/prisma/migrations/20260106112014_relax_unique_constraint_on_pairs/migration.sql
@@ -0,0 +1,11 @@
+/*
+  Warnings:
+
+  - A unique constraint covering the columns `[folder_id,language1,language2,text1,text2]` on the table `pairs` will be added. If there are existing duplicate values, this will fail.
+
+*/
+-- DropIndex
+DROP INDEX "pairs_folder_id_language1_language2_text1_key";
+
+-- CreateIndex
+CREATE UNIQUE INDEX "pairs_folder_id_language1_language2_text1_text2_key" ON "pairs"("folder_id", "language1", "language2", "text1", "text2");
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index a04b695..4a603c2 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -87,7 +87,7 @@ model Pair {
 
   folder Folder @relation(fields: [folderId], references: [id], onDelete: Cascade)
 
-  @@unique([folderId, language1, language2, text1])
+  @@unique([folderId, language1, language2, text1, text2])
   @@index([folderId])
   @@map("pairs")
 }
diff --git a/src/lib/server/services/types.ts b/src/lib/server/services/types.ts
index 55a345f..0094ca2 100644
--- a/src/lib/server/services/types.ts
+++ b/src/lib/server/services/types.ts
@@ -38,7 +38,7 @@ export interface UpdatePairInput {
 export interface CreateTranslationHistoryInput {
   userId?: string;
   sourceText: string;
-  sourceLanguage?: string;
+  sourceLanguage: string;
   targetLanguage: string;
   translatedText: string;
   sourceIpa?: string;