Fix iOS share doing nothing: share directly from the tap

On iPhone, tapping a single-version Download chained two fetches off one
tap (versions list, then the file). iOS only permits navigator.share()
while the tap's transient activation is alive, so the second fetch killed
it and the share rejected with AbortError — which we swallowed as a user
cancel, hence nothing happened.

Mobile now shares the default version straight from the tap via a single
fetch in saveFile(), preserving activation; the version menu stays on
desktop. When Web Share can't take the file, navigate to it so the
browser's save UI shows instead of silently doing nothing.

Author: willuhmjs

src/lib/components/download/DownloadVersionPicker.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
 	import { addToast } from '$lib/stores/toast.svelte';
 	import { formatBytes } from '$lib/utils/format';
-	import { saveFile } from '$lib/utils/download';
+	import { saveFile, isMobileDevice } from '$lib/utils/download';
 	import DownloadIcon from '$lib/components/icons/DownloadIcon.svelte';
 
 	type Version = {
@@ -76,6 +76,15 @@
 	}
 
 	function handleClick() {
+		// On mobile, share the file directly from this tap. A single fetch (inside
+		// saveFile) keeps iOS transient activation alive so navigator.share() is
+		// allowed; opening the version menu first would need a second fetch and the
+		// share would silently fail. Mobile users get the default version — version
+		// selection stays on desktop.
+		if (isMobileDevice()) {
+			void saveFile(downloadId);
+			return;
+		}
 		if (open) {
 			open = false;
 			return;

src/lib/utils/download.ts

@@ -24,26 +24,25 @@ function filenameFromContentDisposition(header: string | null): string | null {
 	return plain?.[1]?.trim() ?? null;
 }
 
-function downloadViaAnchor(blob: Blob, name: string) {
-	const objUrl = URL.createObjectURL(blob);
-	const a = document.createElement('a');
-	a.href = objUrl;
-	a.download = name;
-	document.body.appendChild(a);
-	a.click();
-	a.remove();
-	setTimeout(() => URL.revokeObjectURL(objUrl), 10_000);
-}
-
 /**
  * Save a downloaded file to the user's device.
  *
  * Desktop: opens the file in a new tab (the browser handles the download).
  * Mobile: fetches the real file and opens the native share sheet so users can
  * "Save to Photos" or send it to a contact. `canShare` is tested against the
  * *real* file (which carries a proper MIME type from the endpoint) — an empty,
- * type-less probe returns false on iOS WebKit. Falls back to a plain download
- * when the Web Share API is unavailable (e.g. Firefox on iOS).
+ * type-less probe returns false on iOS WebKit.
+ *
+ * IMPORTANT (iOS): `navigator.share()` is only allowed while the tap's transient
+ * user activation is alive. Callers MUST invoke this directly from the tap with
+ * no awaits in between — the single `await fetch()` here is the only delay the
+ * activation can survive. Chaining another fetch before this (e.g. loading a
+ * version list first) loses activation and iOS rejects the share, usually with
+ * AbortError, which is indistinguishable from the user dismissing the sheet.
+ *
+ * When the Web Share API can't take the file (older iOS, Firefox, unsupported
+ * type), we navigate straight to the file so the browser's own save UI appears —
+ * we never silently do nothing.
  */
 export async function saveFile(id: string, opts?: { filename?: string }): Promise<void> {
 	if (!isMobileDevice()) {
@@ -66,8 +65,8 @@ export async function saveFile(id: string, opts?: { filename?: string }): Promis
 			return;
 		}
 
-		// Share API (with files) unavailable → fall back to a real download.
-		downloadViaAnchor(blob, name);
+		// Web Share (with files) unsupported here → let the browser handle it.
+		window.location.href = fileUrl(id);
 	} catch (e: unknown) {
 		// User dismissed the share sheet — not an error.
 		if (e instanceof DOMException && e.name === 'AbortError') return;