@Rekoo-PS reported that gallery URLs sent via the WhatsApp Business
API render an unbranded "PicPeak - Photo Sharing Platform" preview
even though manual link sends from the WhatsApp app pick up the
per-event rich preview correctly. Two root causes, two fixes:
1. WhatsApp Business and 3rd-party preview services (Twilio,
LinkPreview.net, etc.) don't always crawl with the recognisable
"WhatsApp/X.Y.Z" UA we matched in nginx + galleryOgService.
Extend the regex (both copies) to also catch WhatsAppBot, wa-bot,
LinkPreview, and Slack-ImgProxy.
2. Even with broader UA coverage, some senders cache metadata with
no UA at all and fetch the static SPA shell. That shell's
<title> was hard-coded to "PicPeak - Photo Sharing Platform" —
embarrassingly generic for any self-hosted brand. Switch to
Vite's %VITE_DEFAULT_TITLE% / %VITE_DEFAULT_DESCRIPTION% HTML
substitution so self-hosters can bake their brand into the
fallback at build time. Defaults stay "PicPeak" so the upstream
image doesn't change behaviour for anyone.
The per-event rich preview path (handleGalleryOgRequest, fired on
matched crawler UAs) is unchanged — this only improves the fallback
for unrecognised UAs and for the SPA-shell title that humans see in
their browser tab.
Adds a vite.config plugin to provide the defaults when env vars
aren't set, so unsubstituted "%VITE_..." literals never reach the
built HTML. Adds .env.example entries explaining the override.
Tests: extend galleryOgService.shareImage.test.js with an
isSocialCrawler suite that pins every documented UA (incl. the new
ones) plus three browser UAs (negative) and null/empty edge cases.
Verified locally: `vite build` with VITE_DEFAULT_TITLE="MyBrand"
produces <title>MyBrand</title> + og:title="MyBrand"; without the
env var falls back to "PicPeak".
Refs: #521
Paul Nothaft
b960639035