Forward to named route or rewrite?

Hello,

How can I forward requests that did not match any cached entry to a named route?

I have something like:

location / {
    try_files $uri $uri/ @backend;
}

location @backend {
    rewrite / /index.php;
}

location ~ \.php$ {
    # catch 404s
    if (!-e $request_filename) { rewrite / /index.php last; }

    expires off;
    fastcgi_pass 127.0.0.1:9000;
    fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    include fastcgi_params;
}

Should I place srcache_fetch and srcache_store in location / or @backend? Are there any issues if the fallback is try_files or rewrite?

Thank you in advance!

The issue names no repository file or test; start with the shown location /, @backend, and PHP locations and trace how srcache_fetch and srcache_store interact with try_files and rewrite. Done means documenting a clear recommendation for directive placement and fallback behavior, supported by a reproducible configuration test.