test: add regression test for issue #199 (PDF processing with OpenAI models) (#374)

* test: add regression test for issue #199 (PDF processing with OpenAI models)

Co-Authored-By: Robert Yeakel <robert.yeakel@openrouter.ai>

* fix: use exact model (gpt-4.1) from issue report in regression test

Co-Authored-By: Robert Yeakel <robert.yeakel@openrouter.ai>

* test: add gpt-5 test case to match issue report exactly

Co-Authored-By: Robert Yeakel <robert.yeakel@openrouter.ai>

* docs: remove root cause speculation, keep only known facts from issue

Co-Authored-By: Robert Yeakel <robert.yeakel@openrouter.ai>

* chore: use empty changeset for test-only change

Co-Authored-By: Robert Yeakel <robert.yeakel@openrouter.ai>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Author: robert-j-y

.changeset/mighty-cloths-travel.md

@@ -0,0 +1,2 @@
+---
+---

e2e/issues/issue-199-openai-pdf-processing.test.ts

@@ -0,0 +1,102 @@
+/**
+ * Regression test for GitHub issue #199
+ * https://github.com/OpenRouterTeam/ai-sdk-provider/issues/199
+ *
+ * Issue: "PDF Processing Fails on GPT-4.1 and GPT-5 Models via OpenRouter"
+ *
+ * Reported error:
+ *   AI_RetryError: Failed after 3 attempts. Last error: Provider returned error
+ *
+ * Error details from comments:
+ *   {"error":{"message":"Provider returned error","code":502,"metadata":{
+ *     "raw":"...server_error...","provider_name":"OpenAI"}}}
+ *
+ * This test verifies that PDF processing works with the exact models mentioned
+ * in the issue (gpt-4.1 and gpt-5) using base64-encoded PDFs.
+ */
+import type { ModelMessage } from 'ai';
+
+import { generateText } from 'ai';
+import { describe, expect, it, vi } from 'vitest';
+import { createOpenRouter } from '@/src';
+
+vi.setConfig({
+  testTimeout: 120_000,
+});
+
+describe('Issue #199: PDF Processing Fails on GPT-4.1 and GPT-5 Models via OpenRouter', () => {
+  const openrouter = createOpenRouter({
+    apiKey: process.env.OPENROUTER_API_KEY,
+    baseUrl: `${process.env.OPENROUTER_API_BASE}/api/v1`,
+  });
+
+  // Helper to fetch and encode PDF
+  async function fetchPdfAsBase64(): Promise<string> {
+    const pdfBlob = await fetch('https://bitcoin.org/bitcoin.pdf').then((res) =>
+      res.arrayBuffer(),
+    );
+    return Buffer.from(pdfBlob).toString('base64');
+  }
+
+  it('should process PDF with openai/gpt-4.1', async () => {
+    const model = openrouter('openai/gpt-4.1');
+    const pdfBase64 = await fetchPdfAsBase64();
+
+    const messageHistory: ModelMessage[] = [
+      {
+        role: 'user',
+        content: [
+          {
+            type: 'text',
+            text: 'What is the title of this document? Reply with just the title.',
+          },
+          {
+            type: 'file',
+            data: `data:application/pdf;base64,${pdfBase64}`,
+            mediaType: 'application/pdf',
+          },
+        ],
+      },
+    ];
+
+    const response = await generateText({
+      model,
+      messages: messageHistory,
+    });
+
+    expect(response.text).toBeDefined();
+    expect(response.text.length).toBeGreaterThan(0);
+    expect(response.text.toLowerCase()).toContain('bitcoin');
+  });
+
+  it('should process PDF with openai/gpt-5', async () => {
+    const model = openrouter('openai/gpt-5');
+    const pdfBase64 = await fetchPdfAsBase64();
+
+    const messageHistory: ModelMessage[] = [
+      {
+        role: 'user',
+        content: [
+          {
+            type: 'text',
+            text: 'What is the title of this document? Reply with just the title.',
+          },
+          {
+            type: 'file',
+            data: `data:application/pdf;base64,${pdfBase64}`,
+            mediaType: 'application/pdf',
+          },
+        ],
+      },
+    ];
+
+    const response = await generateText({
+      model,
+      messages: messageHistory,
+    });
+
+    expect(response.text).toBeDefined();
+    expect(response.text.length).toBeGreaterThan(0);
+    expect(response.text.toLowerCase()).toContain('bitcoin');
+  });
+});