+PublicInbox::WWW (PSGI interface) design notes
+
+URL and anchor naming
+---------------------
+
+### Unstable endpoints
+/$INBOX/?r=$GIT_COMMIT -> HTML only
+/$INBOX/new.atom -> Atom feed
+
+#### Optional, relies on Search::Xapian (or Xapian SWIG binding)
+/$INBOX/$MESSAGE_ID/t/ -> HTML content of thread (nested)
+/$INBOX/$MESSAGE_ID/T/ -> HTML content of thread (flat)
+ anchors:
+ #u location of $MESSAGE_ID in URL
+ #m<SHA-1> per-message links, where <SHA-1> is of the Message-ID
+ of each message (stable)
+ #s<NUM> relative numeric position of message in thread (unstable)
+ #i<...> diffstat location for patch emails
+ #Z?<...> per-file diff header location for patch emails
+
+/$INBOX/$MESSAGE_ID/t.atom -> Atom feed for thread
+/$INBOX/$MESSAGE_ID/t.mbox.gz -> gzipped mbox of thread
+
+/$INBOX/$GIT_OID/s/ -> "git show" (via "git apply")
+ This endpoint requires "coderepo" entries configured for
+ a given inbox. It can recreate ("solve") blobs from
+ patch emails using Xapian and git-apply(1). It can also
+ display non-blob content, but that remains a
+ work-in-progress.
+
+/$INBOX/$GIT_OID/s/$FILENAME -> "git show", raw output
+ As above, but shows the raw (usually text/plain) output.
+
+### Stable endpoints
+/$INBOX/$MESSAGE_ID/ -> HTML content
+ anchors:
+ #r location of the current message in thread skeleton
+ (requires Xapian search)
+ #b start of the message body (linked from thread skeleton)
+
+/$INBOX/$MESSAGE_ID -> 301 to /$INBOX/$MESSAGE_ID/
+/$INBOX/$MESSAGE_ID/raw -> raw mbox
+/$INBOX/$MESSAGE_ID/#R -> HTML reply instructions
+
+# Covering up a pre-1.0 design mistake:
+/$INBOX/$MESSAGE_ID/f/ -> 301 to /$INBOX/$MESSAGE_ID/
+
+### Legacy endpoints (may be ambiguous given Message-IDs with similar suffixes)
+/$INBOX/m/$MESSAGE_ID/ -> 301 to /$INBOX/$MESSAGE_ID/
+/$INBOX/m/$MESSAGE_ID.html -> 301 to /$INBOX/$MESSAGE_ID/
+/$INBOX/m/$MESSAGE_ID.txt -> 301 to /$INBOX/$MESSAGE_ID/raw
+/$INBOX/f/$MESSAGE_ID.html -> 301 to /$INBOX/$MESSAGE_ID/
+/$INBOX/f/$MESSAGE_ID.txt [1] -> 301 to /$INBOX/$MESSAGE_ID/raw
+
+/$INBOX/atom.xml [2] -> identical to /$INBOX/new.atom
+
+Additionally, we support git clone/fetch over HTTP (dumb and smart):
+
+ git clone --mirror http://$HOSTNAME/$INBOX
+
+FIXME: we must refactor/cleanup/add tests for most of our CGI before
+adding more endpoints and features.
+
+[1] These URLs were never linked, but only exist as a convenience to folks
+ who edit existing URLs
+
+[2] Do not make this into a 301 since feed readers may not follow them as well
+ as normal browsers do.
+
+Encoding notes
+--------------
+
+Raw HTML and XML should only contain us-ascii characters which render
+to UTF-8. We must not rely on users having the necessary fonts
+installed to render uncommon characters.
+
+Plain text (raw message) endpoints display in the original encoding(s)
+of the original email.
+
+Offline friendly
+----------------
+
+The "/t/", "/T/", "t.mbox.gz" endpoints are designed to be
+useful for reading long threads for users with intermittent
+connections or saved for offline viewing.
+
+Date displays are always absolute, not the "X hours ago"
+pattern commonly seen because readers may be reading a
+previously-saved or cached copy.
+
+HTML URLs end with '/' or "$FILENAME.html". The reason many
+URLs end with the '/' character is so it can trivially be saved
+to a directory via wget or similar tools as "index.html", making
+it easy to mirror all files ending in ".html" using any static
+web server.
+
+Guidelines for using limited HTML
+---------------------------------
+
+We mainly use HTML for linking pages together with <a>.
+We also set <title> to make window management easier.
+
+We favor <pre>-formatted text since public-inbox is intended as a place
+to share and discuss patches and code. Unfortunately, long paragraphs
+tends to be less readable with fixed-width serif fonts which GUI
+browsers default to.
+
+* No graphics, images, or icons at all. We tolerate, but do not
+ encourage the use of GUIs.
+
+* No setting font sizes, power to users to decide those.
+ We will include and document <span class=?> to support colors
+ for user-supplied CSS.
+
+* Only one font type: fixed. This is for accessibility, we must
+ not blow certain elements out-of-proportion with different
+ fonts on the page when a reader increases font size.
+
+* Bold and underline elements are OK since they should render fine
+ regardless of chosen font and gracefully degrade if a display does
+ not support them. Italics and strike-through elements must be
+ avoided as they do not render well with some displays or user-chosen
+ fonts.
+
+* No JavaScript. JS is historically too buggy and insecure, and we will
+ never expect our readers to do either of the following:
+ a) read and audit all our code for on every single page load
+ b) trust us and and run code without reading it
+
+* We only use CSS for one reason: wrapping pre-formatted text
+ This is necessary because unfortunate GUI browsers tend to be
+ prone to layout widening from unwrapped mailers.
+ Do not expect CSS to be enabled, especially with scary things like:
+
+ https://thejh.net/misc/website-terminal-copy-paste
+
+ However, we will try to make it easy for users to supply their
+ own colors via user-side CSS.
+
+CSS classes (for user-supplied CSS)
+-----------------------------------
+
+See examples in contrib/css/ and lib/PublicInbox/WwwText.pm
+(or https://public-inbox.org/meta/_/text/color/ soon)