A .md previewed as its own source, which is reading the punctuation
rather than the notes. It now opens rendered, with Rendered | Source in
the dialog footer for anyone who wants what the file actually says.
Markdown only; a .txt has nothing to toggle between.
Rendering is `marked`, sanitised by DOMPurify -- the one the app already
carries for mail. Markdown is not a safe subset of anything: raw HTML
passes through it by design, so a <script> in a file somebody uploaded or
shared into the account is a script tag unless something takes it out.
Images become links rather than pictures. An image in a Markdown file is
either a relative path, which has no base to resolve against here, or a
URL somewhere else, which fetches on open and tells that server the file
was read -- the tracking pixel this app blocks in mail. The link keeps
the alt text and the address, so nothing vanishes silently.
Fixes the PDF preview while here, which never worked: securityHeaders
put X-Frame-Options: DENY on every response including the blob route, so
the iframe showed Chrome's "refused to connect" where the file should
have been -- in Files today and in mail attachments long before that.
The middleware now leaves a header the route has set, and a PDF served
inline says SAMEORIGIN. Nothing else on the server is framable.
jcoffey-dev