subdomain svg correction

build/Filters/Links.hs

@@ -76,18 +76,21 @@ isInternalPage url
     | "https://" `T.isPrefixOf` url = False
     | otherwise                    = True
 
--- | True if the URL points outside the site's domain.
+-- | True if the URL points outside the site's content host.
 --
---   Uses a strict hostname comparison rather than substring matching, so
---   that a hostile lookalike like @evil-levineuwirth.org.attacker.com@ is
---   correctly classified as external (and gets @rel=noopener noreferrer@
---   plus @target=_blank@ applied).
+--   Only @levineuwirth.org@ and @www.levineuwirth.org@ count as the content
+--   site itself. Sibling subdomains like @git.levineuwirth.org@ (Forgejo) are
+--   distinct services and are classified as external so they receive their
+--   brand icon, @target=_blank@, and @rel=noopener noreferrer@.
+--
+--   Uses strict hostname comparison rather than substring matching, so a
+--   hostile lookalike like @evil-levineuwirth.org.attacker.com@ is also
+--   correctly classified as external.
 isExternal :: Text -> Bool
 isExternal url =
     case extractHost url of
         Nothing   -> False
-        Just host ->
-            not (host == siteHost || ("." <> siteHost) `T.isSuffixOf` host)
+        Just host -> host /= siteHost && host /= "www." <> siteHost
   where
     siteHost = "levineuwirth.org"