🤖 Merge PR DefinitelyTyped#74614 [hotwired__turbo] Fix fetchOptions.headers type by @myabc

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: myabc

types/hotwired__turbo/hotwired__turbo-tests.ts

@@ -94,6 +94,14 @@ StreamActions.log = function() {
     console.log(this.getAttribute("message"));
 };
 
+document.addEventListener("turbo:before-fetch-request", function(event) {
+    // $ExpectType FetchRequestHeaders
+    const headers = event.detail.fetchOptions.headers;
+    headers["Turbo-Referrer"] = window.location.href;
+    // $ExpectType string | undefined
+    headers.Accept;
+});
+
 document.addEventListener("turbo:before-fetch-response", function(e) {
     let { fetchResponse } = e.detail;
     fetchResponse.header("foo");

types/hotwired__turbo/index.d.ts

@@ -78,11 +78,15 @@ export class StreamMessage {
     constructor(fragment: DocumentFragment);
 }
 
+export interface FetchRequestHeaders {
+    [header: string]: string | undefined;
+}
+
 export class FetchRequest {
     body: FormData | URLSearchParams;
     enctype: "application/x-www-form-urlencoded" | "multipart/form-data" | "text/plain";
     fetchOptions: RequestInit;
-    headers: Headers | { [k: string]: any };
+    headers: FetchRequestHeaders;
     method: "get" | "post" | "put" | "patch" | "delete";
     params: URLSearchParams;
     target: HTMLFormElement | HTMLAnchorElement | FrameElement | null;
@@ -489,9 +493,9 @@ export type TurboFrameMissingEvent = CustomEvent<{
 }>;
 
 export type TurboBeforeFetchRequestEvent = CustomEvent<{
-    fetchOptions: RequestInit;
+    fetchOptions: Omit<RequestInit, "headers"> & { headers: FetchRequestHeaders };
     url: URL;
-    resume: (value: any) => void;
+    resume: (value?: unknown) => void;
 }>;
 
 export type TurboBeforeFetchResponseEvent = CustomEvent<{