feat (core): Add finishReason field to NoObjectGeneratedError

.changeset/flat-plums-bake.md

@@ -0,0 +1,5 @@
+---
+'ai': minor
+---
+
+feat (core): Add finishReason field to NoObjectGeneratedError

content/docs/07-reference/05-ai-sdk-errors/ai-no-object-generated-error.mdx

@@ -18,6 +18,7 @@ It can arise due to the following reasons:
 - `text`: The text that was generated by the model. This can be the raw text or the tool call text, depending on the object generation mode.
 - `response`: Metadata about the language model response, including response id, timestamp, and model.
 - `usage`: Request token usage.
+- `finishReason`: Request finish reason. For example 'length' if model generated maximum number of tokens, this could result in a JSON parsing error.
 - `cause`: The cause of the error (e.g. a JSON parsing error). You can use this for more detailed error handling.
 
 ## Checking for this Error
@@ -36,6 +37,7 @@ try {
     console.log('Text:', error.text);
     console.log('Response:', error.response);
     console.log('Usage:', error.usage);
+    console.log('Finish Reason:', error.finishReason);
   }
 }
 ```

packages/ai/core/generate-object/generate-object.test.ts

@@ -801,6 +801,7 @@ describe('output = "object"', () => {
           promptTokens: 10,
           totalTokens: 30,
         },
+        finishReason: 'stop',
       });
     }
 

packages/ai/core/generate-object/generate-object.ts

@@ -556,6 +556,7 @@ export async function generateObject<SCHEMA, RESULT>({
                       'No object generated: the model did not return a response.',
                     response: responseData,
                     usage: calculateLanguageModelUsage(result.usage),
+                    finishReason: result.finishReason,
                   });
                 }
 
@@ -681,6 +682,7 @@ export async function generateObject<SCHEMA, RESULT>({
                     message: 'No object generated: the tool was not called.',
                     response: responseData,
                     usage: calculateLanguageModelUsage(result.usage),
+                    finishReason: result.finishReason,
                   });
                 }
 
@@ -751,6 +753,7 @@ export async function generateObject<SCHEMA, RESULT>({
             text: result,
             response,
             usage: calculateLanguageModelUsage(usage),
+            finishReason: finishReason,
           });
         }
 
@@ -770,6 +773,7 @@ export async function generateObject<SCHEMA, RESULT>({
             text: result,
             response,
             usage: calculateLanguageModelUsage(usage),
+            finishReason: finishReason,
           });
         }
 

packages/ai/core/generate-object/output-strategy.ts

@@ -16,7 +16,11 @@ import {
   createAsyncIterableStream,
 } from '../util/async-iterable-stream';
 import { ObjectStreamPart } from './stream-object-result';
-import { LanguageModelResponseMetadata, LanguageModelUsage } from '../types';
+import {
+  FinishReason,
+  LanguageModelResponseMetadata,
+  LanguageModelUsage,
+} from '../types';
 
 export interface OutputStrategy<PARTIAL, RESULT, ELEMENT_STREAM> {
   readonly type: 'object' | 'array' | 'enum' | 'no-schema';
@@ -64,6 +68,7 @@ const noSchemaOutputStrategy: OutputStrategy<JSONValue, JSONValue, never> = {
       text: string;
       response: LanguageModelResponseMetadata;
       usage: LanguageModelUsage;
+      finishReason: FinishReason;
     },
   ): ValidationResult<JSONValue> {
     return value === undefined
@@ -74,6 +79,7 @@ const noSchemaOutputStrategy: OutputStrategy<JSONValue, JSONValue, never> = {
             text: context.text,
             response: context.response,
             usage: context.usage,
+            finishReason: context.finishReason,
           }),
         }
       : { success: true, value };

packages/ai/core/generate-object/stream-object.test.ts

@@ -1311,6 +1311,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1354,6 +1355,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1403,6 +1405,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1446,6 +1449,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1488,6 +1492,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });
@@ -1530,6 +1535,7 @@ describe('streamObject', () => {
               modelId: 'model-1',
             },
             usage: { completionTokens: 10, promptTokens: 3, totalTokens: 13 },
+            finishReason: 'stop',
           });
         }
       });

packages/ai/core/generate-object/stream-object.ts

@@ -898,6 +898,7 @@ class DefaultStreamObjectResult<PARTIAL, RESULT, ELEMENT_STREAM>
                         text: accumulatedText,
                         response,
                         usage,
+                        finishReason: finishReason,
                       });
                       self.objectPromise.reject(error);
                     }

packages/ai/core/generate-text/generate-text.ts

@@ -576,7 +576,11 @@ A function that attempts to repair a tool call that failed to parse.
 
           return output.parseOutput(
             { text },
-            { response: currentModelResponse.response, usage },
+            {
+              response: currentModelResponse.response,
+              usage,
+              finishReason: currentModelResponse.finishReason,
+            },
           );
         },
         toolCalls: currentToolCalls,

packages/ai/core/generate-text/output.test.ts

@@ -2,6 +2,7 @@ import { fail } from 'assert';
 import { z } from 'zod';
 import { verifyNoObjectGeneratedError } from '../../errors/no-object-generated-error';
 import { object } from './output';
+import { FinishReason } from '../types';
 
 const context = {
   response: {
@@ -14,6 +15,7 @@ const context = {
     completionTokens: 2,
     totalTokens: 3,
   },
+  finishReason: 'length' as FinishReason,
 };
 
 describe('Output.object', () => {
@@ -37,6 +39,7 @@ describe('Output.object', () => {
         message: 'No object generated: could not parse the response.',
         response: context.response,
         usage: context.usage,
+        finishReason: context.finishReason,
       });
     }
   });
@@ -50,6 +53,7 @@ describe('Output.object', () => {
         message: 'No object generated: response did not match schema.',
         response: context.response,
         usage: context.usage,
+        finishReason: context.finishReason,
       });
     }
   });

packages/ai/core/generate-text/output.ts

@@ -9,6 +9,7 @@ import { z } from 'zod';
 import { NoObjectGeneratedError } from '../../errors';
 import { injectJsonInstruction } from '../generate-object/inject-json-instruction';
 import {
+  FinishReason,
   LanguageModel,
   LanguageModelV1CallOptions,
 } from '../types/language-model';
@@ -33,6 +34,7 @@ export interface Output<OUTPUT, PARTIAL> {
     context: {
       response: LanguageModelResponseMetadata;
       usage: LanguageModelUsage;
+      finishReason: FinishReason;
     },
   ): OUTPUT;
 }
@@ -108,6 +110,7 @@ export const object = <OUTPUT>({
       context: {
         response: LanguageModelResponseMetadata;
         usage: LanguageModelUsage;
+        finishReason: FinishReason;
       },
     ) {
       const parseResult = safeParseJSON({ text });
@@ -119,6 +122,7 @@ export const object = <OUTPUT>({
           text,
           response: context.response,
           usage: context.usage,
+          finishReason: context.finishReason,
         });
       }
 
@@ -134,6 +138,7 @@ export const object = <OUTPUT>({
           text,
           response: context.response,
           usage: context.usage,
+          finishReason: context.finishReason,
         });
       }
 

packages/ai/errors/no-object-generated-error.ts

@@ -1,6 +1,7 @@
 import { AISDKError } from '@ai-sdk/provider';
 import { LanguageModelResponseMetadata } from '../core/types/language-model-response-metadata';
 import { LanguageModelUsage } from '../core/types/usage';
+import { FinishReason } from '../core';
 
 const name = 'AI_NoObjectGeneratedError';
 const marker = `vercel.ai.error.${name}`;
@@ -35,24 +36,32 @@ export class NoObjectGeneratedError extends AISDKError {
    */
   readonly usage: LanguageModelUsage | undefined;
 
+  /**
+  Reason why the model finished generating a response.
+   */
+  readonly finishReason: FinishReason | undefined;
+
   constructor({
     message = 'No object generated.',
     cause,
     text,
     response,
     usage,
+    finishReason,
   }: {
     message?: string;
     cause?: Error;
     text?: string;
     response: LanguageModelResponseMetadata;
     usage: LanguageModelUsage;
+    finishReason: FinishReason;
   }) {
     super({ name, message, cause });
 
     this.text = text;
     this.response = response;
     this.usage = usage;
+    this.finishReason = finishReason;
   }
 
   static isInstance(error: unknown): error is NoObjectGeneratedError {
@@ -66,11 +75,15 @@ export function verifyNoObjectGeneratedError(
     message: string;
     response: LanguageModelResponseMetadata;
     usage: LanguageModelUsage;
+    finishReason: FinishReason;
   },
 ) {
   expect(NoObjectGeneratedError.isInstance(error)).toBeTruthy();
   const noObjectGeneratedError = error as NoObjectGeneratedError;
   expect(noObjectGeneratedError.message).toStrictEqual(expected.message);
   expect(noObjectGeneratedError.response).toStrictEqual(expected.response);
   expect(noObjectGeneratedError.usage).toStrictEqual(expected.usage);
+  expect(noObjectGeneratedError.finishReason).toStrictEqual(
+    expected.finishReason,
+  );
 }