I encounter this issue both with Lagrange and Asuka browsers: requesting gemini://hannuhartikainen.fi/twinwiki/Applications and services returns right page; but requesting gemini://hannuhartikainen.fi/twinwiki/Applications and services/ (note the last character) returns the front page.
P.S.: Thank you for twinwiki, great idea!
This is somewhat intentional. The URL with and without a trailing slash are two different URLs even if some people on the modern web think otherwise. For now, the version with trailing slash does not have any defined behavior (but it could) and so it's redirected to the root page by the default URL handler.
It's trivial to "fix", but I don't like URL redirects where they're not needed. Ie. I'm not planning to change it.
On the other hand if you care enough to fix it and set up your own instance, I'll accept the patch. I'd even be happy to let you (or someone else) maintain the codebase. I'm not really planning to work on it myself.
Ok, noted. Not sure if I can maintain codebase, even though it's clean and nice - I just don't have much time.