You click a link and it works about half the time. It is not random. One class of link is fine, another class is malformed by default. Here is what I checked on your Mac, why the failures happen, and the fix that now carries into every chat.
default browser: Firefox3 live pages verified 200root cause: relative-path links
What this page says, in plain words: When I give you a link to a website, it works, because your computer knows to open websites in Firefox. When I give you a link to a file on your own computer, it often does nothing, because I wrote the address in a lazy short way the click cannot follow. From now on I write the full website address for things you should open, and for files on your computer I open them for you instead of giving a link that goes nowhere.
What I checked
Your default browser is Firefox. On this Mac, https, http, and .html all route to org.mozilla.firefox in LaunchServices. Both Firefox and Chrome binaries are present and healthy.
Three of your live pages return HTTP 200. The landing index, /chats, and /plans all answered green when I curled them.
Why half open and half don't
Relative-path links are the main offender. The harness default tells me to write file links as a bare relative path like [page](some/local/path.html). That has no scheme in front of it, so a click has nowhere to land. It does nothing, or it pops the in-app preview pane you dislike. This fires every turn because the base instruction pushes it.
Raw file links snap at the first space. Your real paths carry spaces and apostrophes, like IF YOU CAN'T FIND SOMETHING ITS HERE and New Desktop. An unencoded file:// link breaks at the first space and dies.
A clickable local-file link opens the preview pane, never a browser. So even a correct local link lands in the place you do not want it.
The fix I locked in
Browser content gets the absolute live URL, curl-verified 200 before I hand it over. No relative links, no local-file links for anything clickable.
Local files get a real open command that runs, with the path shown as plain copyable text instead of a clickable link that would trigger the preview.
Written into memory (feedback_force_open_links.md) with today's diagnosis, so it overrides the harness default across every future chat.