Comment by dxjones

I tried that, and it gets me part way there, but the internals of the WordPress index.php come into play to prevent this being a solution.

1. WordPress wants the "Page" name to come last, so I followed your suggestion, but with "app" moved to the end. Same idea as your rule, but rearranged. See .htaccess appended below.

2. The REQUEST_URI is "alpha/beta/app", and the QUERY_STRING "p1=alpha&p2=beta", ...

but the WordPress index.php comes into play and seems to do a REDIRECT (so my app never gets a chance to run)

so that REQUEST_URI becomes "app" and QUERY_STRING is empty. My app code runs, but now it is too late; the parameters are gone.

Any further suggestions?

  # .htaccess
  
  <IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteBase /
  RewriteRule ^index\.php$ - [L]
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^([^/]+)/([^/]+)/app$ /app/?p1=$1&p2=$2 [QSA,L]
  </IfModule>
  
  # BEGIN WordPress
  <IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteBase /
  RewriteRule ^index\.php$ - [L]
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule . /index.php [L]
  </IfModule>
  
  # END WordPress