fix: keep the provider user agent when called through the AI SDK

.changeset/keep-provider-user-agent.md

@@ -0,0 +1,5 @@
+---
+'@openrouter/ai-sdk-provider': patch
+---
+
+Keep the `ai-sdk/openrouter/<version>` user agent identifier on requests made through the AI SDK (`generateText`, `embed`, `generateImage`, and so on). The AI SDK sends its own `user-agent` call header, which used to replace the provider identifier. The identifier is now appended to it, so requests carry both `ai/<version>` and `ai-sdk/openrouter/<version>`. A `User-Agent` set in `createOpenRouter({ headers })` is still not modified.

src/chat/index.ts

@@ -28,7 +28,6 @@ import {
   NoContentGeneratedError,
 } from '@ai-sdk/provider';
 import {
-  combineHeaders,
   createEventSourceResponseHandler,
   createJsonResponseHandler,
   generateId,
@@ -51,6 +50,7 @@ import {
 import { mergeProviderRouting } from '../utils/merge-provider-routing';
 import { resolveReasoning } from '../utils/resolve-reasoning';
 import { withStreamErrorHandling } from '../utils/with-stream-error-handling';
+import { combineHeadersWithUserAgent } from '../utils/with-user-agent-suffix';
 import {
   restoreOpenRouterConfig,
   serializeOpenRouterModel,
@@ -332,7 +332,10 @@ export class OpenRouterChatLanguageModel implements LanguageModelV4 {
         path: '/chat/completions',
         modelId: this.modelId,
       }),
-      headers: combineHeaders(this.config.headers(), options.headers),
+      headers: combineHeadersWithUserAgent(
+        this.config.headers(),
+        options.headers,
+      ),
       body: args,
       failedResponseHandler: openrouterFailedResponseHandler,
       successfulResponseHandler: createJsonResponseHandler(
@@ -670,7 +673,10 @@ export class OpenRouterChatLanguageModel implements LanguageModelV4 {
         path: '/chat/completions',
         modelId: this.modelId,
       }),
-      headers: combineHeaders(this.config.headers(), options.headers),
+      headers: combineHeadersWithUserAgent(
+        this.config.headers(),
+        options.headers,
+      ),
       body: {
         ...args,
         stream: true,

src/completion/index.ts

@@ -22,7 +22,6 @@ import {
   UnsupportedFunctionalityError,
 } from '@ai-sdk/provider';
 import {
-  combineHeaders,
   createEventSourceResponseHandler,
   createJsonResponseHandler,
   generateId,
@@ -40,6 +39,7 @@ import {
 import { mergeProviderRouting } from '../utils/merge-provider-routing';
 import { resolveReasoning } from '../utils/resolve-reasoning';
 import { withStreamErrorHandling } from '../utils/with-stream-error-handling';
+import { combineHeadersWithUserAgent } from '../utils/with-user-agent-suffix';
 import {
   restoreOpenRouterConfig,
   serializeOpenRouterModel,
@@ -225,7 +225,10 @@ export class OpenRouterCompletionLanguageModel implements LanguageModelV4 {
         path: '/completions',
         modelId: this.modelId,
       }),
-      headers: combineHeaders(this.config.headers(), options.headers),
+      headers: combineHeadersWithUserAgent(
+        this.config.headers(),
+        options.headers,
+      ),
       body: args,
       failedResponseHandler: openrouterFailedResponseHandler,
       successfulResponseHandler: createJsonResponseHandler(
@@ -347,7 +350,10 @@ export class OpenRouterCompletionLanguageModel implements LanguageModelV4 {
         path: '/completions',
         modelId: this.modelId,
       }),
-      headers: combineHeaders(this.config.headers(), options.headers),
+      headers: combineHeadersWithUserAgent(
+        this.config.headers(),
+        options.headers,
+      ),
       body: {
         ...args,
         stream: true,

src/embedding/index.ts

@@ -9,13 +9,13 @@ import type {
 } from '../types/openrouter-embedding-settings';
 
 import {
-  combineHeaders,
   createJsonResponseHandler,
   postJsonToApi,
 } from '@ai-sdk/provider-utils';
 import { openrouterFailedResponseHandler } from '../schemas/error-response';
 import { OpenRouterProviderMetadataSchema } from '../schemas/provider-metadata';
 import { mergeProviderRouting } from '../utils/merge-provider-routing';
+import { combineHeadersWithUserAgent } from '../utils/with-user-agent-suffix';
 import { OpenRouterEmbeddingResponseSchema } from './schemas';
 
 type OpenRouterEmbeddingConfig = {
@@ -93,7 +93,7 @@ export class OpenRouterEmbeddingModel implements EmbeddingModelV4 {
         path: '/embeddings',
         modelId: this.modelId,
       }),
-      headers: combineHeaders(this.config.headers(), headers),
+      headers: combineHeadersWithUserAgent(this.config.headers(), headers),
       body: args,
       failedResponseHandler: openrouterFailedResponseHandler,
       successfulResponseHandler: createJsonResponseHandler(

src/evaluation/index.ts

@@ -30,14 +30,14 @@ import {
   UnsupportedFunctionalityError,
 } from '@ai-sdk/provider';
 import {
-  combineHeaders,
   createJsonResponseHandler,
   parseProviderOptions,
   postJsonToApi,
   removeUndefinedEntries,
 } from '@ai-sdk/provider-utils';
 import { getFileUrl } from '../chat/file-url-utils';
 import { openrouterFailedResponseHandler } from '../schemas/error-response';
+import { combineHeadersWithUserAgent } from '../utils/with-user-agent-suffix';
 import {
   OpenRouterDecisionsProviderOptionsSchema,
   OpenRouterDecisionsResponseSchema,
@@ -177,7 +177,7 @@ export class OpenRouterEvaluationModel
       responseHeaders,
     } = await postJsonToApi({
       url: this.config.url({ path: '/decisions' }),
-      headers: combineHeaders(this.config.headers(), headers),
+      headers: combineHeadersWithUserAgent(this.config.headers(), headers),
       body,
       failedResponseHandler: openrouterFailedResponseHandler,
       successfulResponseHandler: createJsonResponseHandler(

src/image/index.ts

@@ -16,13 +16,13 @@ import {
   UnsupportedFunctionalityError,
 } from '@ai-sdk/provider';
 import {
-  combineHeaders,
   createJsonResponseHandler,
   postJsonToApi,
 } from '@ai-sdk/provider-utils';
 import { buildFileDataUrl } from '../chat/file-url-utils';
 import { openrouterFailedResponseHandler } from '../schemas/error-response';
 import { mergeProviderRouting } from '../utils/merge-provider-routing';
+import { combineHeadersWithUserAgent } from '../utils/with-user-agent-suffix';
 import { OpenRouterImageResponseSchema } from './schemas';
 
 type OpenRouterImageConfig = {
@@ -136,7 +136,7 @@ export class OpenRouterImageModel implements ImageModelV4 {
         path: '/images',
         modelId: this.modelId,
       }),
-      headers: combineHeaders(this.config.headers(), headers),
+      headers: combineHeadersWithUserAgent(this.config.headers(), headers),
       body,
       failedResponseHandler: openrouterFailedResponseHandler,
       successfulResponseHandler: createJsonResponseHandler(

src/reranking/index.ts

@@ -11,12 +11,12 @@ import type {
 } from '../types/openrouter-reranking-settings';
 
 import {
-  combineHeaders,
   createJsonResponseHandler,
   postJsonToApi,
   removeUndefinedEntries,
 } from '@ai-sdk/provider-utils';
 import { openrouterFailedResponseHandler } from '../schemas/error-response';
+import { combineHeadersWithUserAgent } from '../utils/with-user-agent-suffix';
 import { OpenRouterRerankingResponseSchema } from './schemas';
 
 type OpenRouterRerankingConfig = {
@@ -97,7 +97,7 @@ export class OpenRouterRerankingModel implements RerankingModelV4 {
         path: '/rerank',
         modelId: this.modelId,
       }),
-      headers: combineHeaders(this.config.headers(), headers),
+      headers: combineHeadersWithUserAgent(this.config.headers(), headers),
       body: args,
       failedResponseHandler: openrouterFailedResponseHandler,
       successfulResponseHandler: createJsonResponseHandler(

src/tests/user-agent.test.ts

@@ -0,0 +1,196 @@
+import {
+  embed,
+  experimental_evaluate as evaluate,
+  generateImage,
+  generateText,
+  experimental_generateVideo as generateVideo,
+  rerank,
+  streamText,
+} from 'ai';
+import { describe, expect, it } from 'vitest';
+import { createOpenRouter } from '../provider';
+import { VERSION } from '../version';
+
+const PROVIDER_USER_AGENT = `ai-sdk/openrouter/${VERSION}`;
+const AI_USER_AGENT = /\bai\/\d+\.\d+\.\d+/;
+
+const CHAT_RESPONSE = {
+  id: 'chatcmpl-1',
+  model: 'openai/gpt-4o-mini',
+  choices: [
+    {
+      index: 0,
+      message: { role: 'assistant', content: 'Hello' },
+      finish_reason: 'stop',
+    },
+  ],
+};
+
+const RESPONSES: Record<string, unknown> = {
+  '/api/v1/chat/completions': CHAT_RESPONSE,
+  '/api/v1/completions': {
+    id: 'cmpl-1',
+    model: 'openai/gpt-3.5-turbo-instruct',
+    choices: [{ index: 0, text: 'Hello', finish_reason: 'stop' }],
+  },
+  '/api/v1/embeddings': {
+    object: 'list',
+    data: [{ object: 'embedding', embedding: [0.1, 0.2], index: 0 }],
+    model: 'openai/text-embedding-3-small',
+  },
+  '/api/v1/rerank': {
+    model: 'cohere/rerank-v3.5',
+    results: [{ index: 0, relevance_score: 0.9 }],
+  },
+  '/api/v1/images': {
+    created: 1,
+    data: [{ b64_json: 'iVBORw0KGgo=' }],
+  },
+  '/api/alpha/decisions': {
+    id: 'gen-dec-1',
+    model: 'typesafe/jev-1.13',
+    answers: { q: { type: 'noul', noul: 0.5 } },
+  },
+};
+
+function createProvider() {
+  const userAgents: string[] = [];
+  const provider = createOpenRouter({
+    apiKey: 'test-api-key',
+    fetch: async (input, init) => {
+      userAgents.push(new Headers(init?.headers).get('user-agent') ?? '');
+      const path = new URL(String(input)).pathname;
+      const body = RESPONSES[path];
+      if (body === undefined) {
+        return new Response(
+          JSON.stringify({ error: { message: 'Not found', code: 400 } }),
+          { status: 400, headers: { 'content-type': 'application/json' } },
+        );
+      }
+      return new Response(JSON.stringify(body), {
+        status: 200,
+        headers: { 'content-type': 'application/json' },
+      });
+    },
+  });
+  return { provider, userAgents };
+}
+
+function expectBothUserAgents(userAgent: string | undefined) {
+  expect(userAgent).toMatch(AI_USER_AGENT);
+  expect(userAgent).toContain(PROVIDER_USER_AGENT);
+}
+
+describe('user agent through the AI SDK', () => {
+  it('keeps the provider identifier for generateText with a chat model', async () => {
+    const { provider, userAgents } = createProvider();
+    await generateText({
+      model: provider.chat('openai/gpt-4o-mini'),
+      prompt: 'Hi',
+    });
+    expectBothUserAgents(userAgents[0]);
+  });
+
+  it('keeps the provider identifier for streamText with a chat model', async () => {
+    const { provider, userAgents } = createProvider();
+    const result = streamText({
+      model: provider.chat('openai/gpt-4o-mini'),
+      prompt: 'Hi',
+      onError: () => {},
+    });
+    await result.consumeStream();
+    // `ai` 7.0.103 sends no `ai/<version>` user agent for streamText.
+    expect(userAgents[0]).toContain(PROVIDER_USER_AGENT);
+  });
+
+  it('keeps the provider identifier for generateText with a completion model', async () => {
+    const { provider, userAgents } = createProvider();
+    await generateText({
+      model: provider.completion('openai/gpt-3.5-turbo-instruct'),
+      prompt: 'Hi',
+    });
+    expectBothUserAgents(userAgents[0]);
+  });
+
+  it('keeps the provider identifier for embed', async () => {
+    const { provider, userAgents } = createProvider();
+    await embed({
+      model: provider.embeddingModel('openai/text-embedding-3-small'),
+      value: 'Hi',
+    });
+    expectBothUserAgents(userAgents[0]);
+  });
+
+  it('keeps the provider identifier for rerank', async () => {
+    const { provider, userAgents } = createProvider();
+    await rerank({
+      model: provider.rerankingModel('cohere/rerank-v3.5'),
+      query: 'Hi',
+      documents: ['a'],
+    });
+    // `ai` 7.0.103 sends no `ai/<version>` user agent for rerank.
+    expect(userAgents[0]).toContain(PROVIDER_USER_AGENT);
+  });
+
+  it('keeps the provider identifier for generateImage', async () => {
+    const { provider, userAgents } = createProvider();
+    await generateImage({
+      model: provider.imageModel('openai/gpt-image-1'),
+      prompt: 'A cat',
+    });
+    expectBothUserAgents(userAgents[0]);
+  });
+
+  it('keeps the provider identifier for generateVideo', async () => {
+    const { provider, userAgents } = createProvider();
+    // The mocked submit request fails; only its headers matter here.
+    await expect(
+      generateVideo({
+        model: provider.videoModel('google/veo-3'),
+        prompt: 'A cat',
+        maxRetries: 0,
+      }),
+    ).rejects.toThrow();
+    expectBothUserAgents(userAgents[0]);
+  });
+
+  it('keeps the provider identifier for evaluate', async () => {
+    const { provider, userAgents } = createProvider();
+    await evaluate({
+      model: provider.decisionModel('typesafe/jev-1.13'),
+      state: 'x',
+      questions: { q: { type: 'boolean', instructions: 'Is it?' } },
+    });
+    expectBothUserAgents(userAgents[0]);
+  });
+
+  it('sends a custom call-level User-Agent verbatim on a direct model call', async () => {
+    const { provider, userAgents } = createProvider();
+    await provider.chat('openai/gpt-4o-mini').doGenerate({
+      prompt: [{ role: 'user', content: [{ type: 'text', text: 'Hi' }] }],
+      headers: { 'user-agent': 'my-app/1.0' },
+    });
+    expect(userAgents[0]).toMatch(/^my-app\/1\.0\b/);
+    expect(userAgents[0]).not.toContain(PROVIDER_USER_AGENT);
+  });
+
+  it('still sends a user-specified provider User-Agent through generateText', async () => {
+    const userAgents: string[] = [];
+    const provider = createOpenRouter({
+      apiKey: 'test-api-key',
+      headers: { 'User-Agent': 'my-app/1.0' },
+      fetch: async (_input, init) => {
+        userAgents.push(new Headers(init?.headers).get('user-agent') ?? '');
+        return new Response(JSON.stringify(CHAT_RESPONSE), {
+          status: 200,
+          headers: { 'content-type': 'application/json' },
+        });
+      },
+    });
+    await generateText({
+      model: provider.chat('openai/gpt-4o-mini'),
+      prompt: 'Hi',
+    });
+    expect(userAgents[0]).not.toContain(PROVIDER_USER_AGENT);
+  });
+});