.htaccess silent redirection to subfolder - regex

Question

I would like to redirect silently all requests of a domain to a subfolder if the folder / file doesn't exist.
Unfortunately some scenarios doesn't work or work non-silently.
works: http://mydomain.com/index.html -- it shows the content of production/index.html
does not work: http://mydomain.com/ -- it doesn't show production/index.html
works: http://mydomain.com/test/ -- it shows the content of production/test/index.html
does not work: http://mydomain.com/test -- it redirects the url (instead of a silent redirection) to http://mydomain.com/production/test/ and shows the content of production/test/index.html
Below is the .htaccess file:
Options -Indexes +SymLinksIfOwnerMatch
DirectoryIndex index.php index.html
RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_URI} !^/production/
# Don't apply to URLs that go to existing files or folders
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# Rewrite all those to insert /production folder
RewriteRule ^(.*)$ /production/$1 [L]

Answer 1

It is because mod_dir is appending a trailing slash after mod_rewrite execution. Change your rules to this to overcome this issue:
DirectorySlash Off
Options -Indexes +SymLinksIfOwnerMatch
DirectoryIndex index.php index.html
RewriteEngine on
RewriteBase /
# add a trailing slash for directories
RewriteCond %{REQUEST_FILENAME} -d
RewriteCond %{THE_REQUEST} \s/+([^.]*?[^/])[?\s]
RewriteRule [^/]$ /%1/ [L,R=302,NE]
# take care of landing page:
RewriteRule ^/?$ production/ [L]
# Don't apply to URLs that go to existing files or folders
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# Rewrite all those to insert /production folder
RewriteRule ^((?!production).+)$ production/$1 [L,NC]