fix: upload provider files with a lowercase extension

deno.json

@@ -1,6 +1,6 @@
 {
   "name": "@alphaxiv/agents",
-  "version": "0.7.4",
+  "version": "0.7.5",
   "license": "MIT",
   "fmt": {
     "lineWidth": 120

src/adapters/open_responses/history.ts

@@ -98,12 +98,17 @@ export interface OpenResponsesFiles extends OpenResponsesFilesConfig {
   uploaded: Set<string>;
 }
 
-/** Providers check the filename extension on upload, and the last segment of a URL often has none. */
+/**
+ * Providers check the filename extension on upload, and the last segment of a URL often has none.
+ * OpenAI compares it case-sensitively and rejects ".JPG", so the extension is always sent lowercase.
+ */
 function uploadFileName(url: string, mimeType: string): string {
   const name = getFileNameFromUrl(url) ?? "file";
   const subtype = mimeType.split("/")[1];
   const accepted = subtype === "jpeg" ? ["jpeg", "jpg"] : [subtype];
-  if (accepted.some((extension) => name.toLowerCase().endsWith(`.${extension}`))) return name;
+  const dotIndex = name.lastIndexOf(".");
+  const extension = dotIndex > 0 ? name.slice(dotIndex + 1).toLowerCase() : "";
+  if (accepted.includes(extension)) return `${name.slice(0, dotIndex)}.${extension}`;
   return `${name}.${accepted.at(-1)}`;
 }
 

tests/adapters/provider-files.test.ts

@@ -327,7 +327,7 @@ Deno.test("without a fileStore the input keeps image_url and file_data", async (
   });
 });
 
-Deno.test("an upload is named with the extension for its mime type when the URL has none", async () => {
+Deno.test("an upload is named with the lowercase extension for its mime type", async () => {
   using _fetch = stubFetch();
   const fake = createFakeClient("file");
   const adapter = openAIModel({ model: "gpt-5.6-luna", client: fake.client, fileStore: createMemoryStore() });
@@ -343,7 +343,7 @@ Deno.test("an upload is named with the extension for its mime type when the URL
   assertEquals(fake.created.map((c) => c.filename), [
     "1706.03762v7.pdf",
     "abc.jpg",
-    "Logo.PNG",
+    "Logo.png",
     "photo.jpeg",
     "photo.jpg",
   ]);