fix(ai): Fix responseSchema bug (#9791)

hsubox76 · web-flow · commit f87c15e97af9 · 2026-03-31T10:33:43.000-07:00
diff --git a/.changeset/shiny-papayas-begin.md b/.changeset/shiny-papayas-begin.md
@@ -0,0 +1,5 @@
+---
+'@firebase/ai': patch
+---
+
+Fixed a bug that causes the model to error if the user specifies `responseSchema` or `responseJsonSchema`.
diff --git a/packages/ai/src/models/generative-model.test.ts b/packages/ai/src/models/generative-model.test.ts
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 import { use, expect } from 'chai';
-import { GenerativeModel } from './generative-model';
+import { GenerativeModel, validateGenerationConfig } from './generative-model';
 import {
   FunctionCallingMode,
   AI,
@@ -956,3 +956,73 @@ describe('GenerativeModel dispatch logic', () => {
     });
   });
 });
+
+describe('validateGenerationConfig', () => {
+  it('does not allow setting both thinkingBudget and thinkingLevel', () => {
+    expect(() => {
+      validateGenerationConfig({
+        thinkingConfig: {
+          thinkingBudget: 200
+        }
+      });
+    }).to.not.throw();
+    expect(() => {
+      validateGenerationConfig({
+        thinkingConfig: {
+          thinkingLevel: ThinkingLevel.LOW
+        }
+      });
+    }).to.not.throw();
+    expect(() => {
+      validateGenerationConfig({
+        thinkingConfig: {
+          thinkingBudget: 200,
+          thinkingLevel: ThinkingLevel.LOW
+        }
+      });
+    }).to.throw();
+  });
+  it('does not allow setting both responseSchema and responseJsonSchema', () => {
+    expect(() => {
+      validateGenerationConfig({
+        responseSchema: {},
+        responseMimeType: 'application/json'
+      });
+    }).to.not.throw();
+    expect(() => {
+      validateGenerationConfig({
+        responseJsonSchema: {},
+        responseMimeType: 'application/json'
+      });
+    }).to.not.throw();
+    expect(() => {
+      validateGenerationConfig({
+        responseSchema: {},
+        responseJsonSchema: {},
+        responseMimeType: 'application/json'
+      });
+    }).to.throw();
+  });
+  it(
+    'throws if responseSchema or responseJsonSchema are set' +
+      ' and responseMimeType is not "application/json"',
+    () => {
+      expect(() => {
+        validateGenerationConfig({
+          responseSchema: {}
+        });
+      }).to.throw();
+      expect(() => {
+        validateGenerationConfig({
+          responseJsonSchema: {}
+        });
+      }).to.throw();
+      expect(() => {
+        validateGenerationConfig({
+          responseJsonSchema: {},
+          responseMimeType: 'text/plain'
+        });
+      }).to.throw();
+    }
+  );
+});
diff --git a/packages/ai/src/models/generative-model.ts b/packages/ai/src/models/generative-model.ts
@@ -190,7 +190,9 @@ export class GenerativeModel extends AIModel {
  * Client-side validation of some common `GenerationConfig` pitfalls, in order
  * to save the developer a wasted request.
  */
-function validateGenerationConfig(generationConfig: GenerationConfig): void {
+export function validateGenerationConfig(
+  generationConfig: GenerationConfig
+): void {
   if (
     // != allows for null and undefined. 0 is considered "set" by the model
     generationConfig.thinkingConfig?.thinkingBudget != null &&
@@ -214,11 +216,12 @@ function validateGenerationConfig(generationConfig: GenerationConfig): void {
   if (
     (generationConfig.responseSchema != null ||
       generationConfig.responseJsonSchema != null) &&
-    generationConfig.responseMimeType
+    generationConfig.responseMimeType !== 'application/json'
   ) {
     throw new AIError(
       AIErrorCode.UNSUPPORTED,
-      `responseMimeType must be set if responseSchema or responseJsonSchema are set.`
+      `responseMimeType must be set to "application/json" if` +
+        ` responseSchema or responseJsonSchema are set.`
     );
   }
 }

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +'@firebase/ai': patch
 +---
++
 +Fixed a bug that causes the model to error if the user specifies `responseSchema` or `responseJsonSchema`.