diff --git a/src/api_validation.test.ts b/src/api_validation.test.ts
index d0120de..6af7811 100644
--- a/src/api_validation.test.ts
+++ b/src/api_validation.test.ts
@@ -391,6 +391,19 @@ describe('Input Validation', () => {
       expect(response.statusCode).toBe(400);
     });
 
+    test('rejects lineId exceeding 200 characters', async () => {
+      const response = await server.inject({
+        method: 'POST',
+        url: '/api/v1/session',
+        body: {
+          productionId: '1',
+          lineId: 'x'.repeat(201),
+          username: 'user'
+        }
+      });
+      expect(response.statusCode).toBe(400);
+    });
+
     test('rejects username exceeding 200 characters', async () => {
       const response = await server.inject({
         method: 'POST',
diff --git a/src/models.ts b/src/models.ts
index b38f1ea..062f6e4 100644
--- a/src/models.ts
+++ b/src/models.ts
@@ -306,7 +306,7 @@ export const DetailedProductionResponse = Type.Object({
 
 export const NewSession = Type.Object({
   productionId: Type.String({ minLength: 1, pattern: '^[0-9]+$' }),
-  lineId: Type.String({ minLength: 1 }),
+  lineId: Type.String({ minLength: 1, maxLength: 200 }),
   username: Type.String({ minLength: 1, maxLength: 200 })
 });
 
@@ -316,7 +316,7 @@ export const SessionResponse = Type.Object({
 });
 
 export const SdpAnswer = Type.Object({
-  sdpAnswer: Type.String()
+  sdpAnswer: Type.String({ maxLength: 65536 })
 });
 
 export const ErrorResponse = Type.Object({