Add trailing slash for specific directory (Slim framework)

Question

What I want to achieve:

www.mydomain/app => www.mydomain/app/ 

Only for this url.

I'm using Slim Framework and this is how I handle my route:

$app->get('/', function () use ($app){
    // Some code goes here
});

---

What I've tried:

1) Any results with these:

$app->get('/?', function () use ($app){
    // Some code goes here
});

$app->get('(/)', function () use ($app){
    // Some code goes here
});

---

2) This one works great but brokes my other routes:

RewriteCond $0 !^app(/|$)
RewriteRule ^[^\.]+[^/]$ /$0/ [R=301,L]

For example I got route

www.mydomain.com/app/panel 

after rules above it redirects me to

www.mydomain.com/panel/

---

3) This one also works but it adds slashes for every url:

# Add a trailing slash to any non-existent files
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_URI} !(.*)/$
RewriteRule ^(.*)$ %{REQUEST_URI}/ [R=301,L]

---

4) This one redirects me to www.mydomain.com/

RewriteCond %{REQUEST_URI} ^/(app|foo|bar)$
RewriteRule ^(.*)$ http://%{HTTP_HOST}/$1/ [R=301,L]

Thank you for any guidance or references that might help me.

UPDATE:

My root directory .htaccess:

AddHandler php53 .php
Action php53 /cgi-bin/php53.cgi


DirectoryIndex index.php
<ifModule mod_gzip.c>
  mod_gzip_on Yes
  mod_gzip_dechunk Yes
  mod_gzip_item_include file \.(html?|txt|css|js|php|pl)$
  mod_gzip_item_include handler ^cgi-script$
  mod_gzip_item_include mime ^text/.*
  mod_gzip_item_include mime ^application/x-javascript.*
  mod_gzip_item_exclude mime ^image/.*
  mod_gzip_item_exclude rspheader ^Content-Encoding:.*gzip.*
</ifModule>
RewriteEngine on

#RewriteCond   %{REMOTE_HOST}  !^192\..*
#RewriteRule   ^(.*)         http://www.randomurl.com/$1 [R,L]



RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?rqp=$1 [L,QSA]
php_flag last_modified 1
php_flag register_globals 0
php_flag display_errors 1
php_flag magic_quotes_gpc 1

php_flag error_reporting E_ALL

AddDefaultCharset utf-8

#AddType  text/html .d

AddHandler application/x-httpd-php .dll

My app directory .htaccess:

RewriteEngine On

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^ index.php [QSA,L]

Answer 1

If all you want is this www.mydomain/app => www.mydomain/app/

Then you can just add this line in your DOCUMENT_ROOT/.htacces:

DirectorySlash On

as the first line in your root .htaccess