Reverse proxy & rewriting

Sorry for my typo on {~ AppSession} , i actually abbreviated it to post here.
The /wi_studio/foo/bar did not work, however I tried another workaround based on the post Proxy/Rewrite Priority. It allowed the /wistudio proxy to work.

my caddy file looks like this now: -

Blockquote

0.0.0.0:{$CADDY_PROXY_PORT} {
    gzip
    root {$DATA_DIR}/proxy
    log   / stdout  "{combined}  UPSTREAM: {upstream} REWRITE: {rewrite_uri} TOKEN: {>X-App-Token} COOKIE:{~AppSession}"


    # CORS allow all
    # cors /

    # Re-write / to /login if X-App-Token does not exist
    rewrite {
        if {>X-App-Token} is  ""
        if {path} is /
        to /login{uri}
    }

    rewrite {
        regexp ^/wistudio/.*$
        to /wi_studio{uri}
    }

    # Re-write / to /web_server
    rewrite {
        #regexp ^/.*$
        to  /web_server{uri}
    }

    
    proxy /login {$LOGIN_SERVICE} {
        # Set downstream header cookie
        header_downstream X-App-Token {~AppSession}
        header_upstream X-App-Token {~AppSession}
        without /login
    }

    

    # Proxy /web_server and remove proxy prefix since 
    # it is the / 
    proxy /web_server {$WEB_SERVICE} {
        #transparent
        without /web_server
        except /wistudio 
        # Set upstream+downstream header cookie
        header_upstream X-App-Token {~AppSession}
        header_downstream X-App-Token {~AppSession}
    }
  
}

# Proxy /wistudio
0.0.0.0:{$CADDY_PROXY_PORT}/wistudio {
    proxy / {$WISTUDIO_SERVICE} {
        transparent
        # without /wi_studio
        # Set upstream header cookie
        header_upstream X-App-Token {~AppSession}
        header_downstream X-App-Token {~AppSession}
    }
}