Markdown Preview in Helix with go-grip

I spend a fair bit of time editing Markdown files in Helix. By and large, these are GitHub Flavored Markdown, and I get sick of needing to push up my changes to see how GitHub would actually render the source code. Today I went ahead and found a solution.

go-grip is a handy little tool that launches a live-reload webserver for rendering GitHub Flavored Markdown files. Just install it and drop this in your Helix config:

[keys.normal.C-p]
g = ":sh pkill go-grip || true; go-grip --theme dark %{buffer_name} > /dev/null || true"

or in home-manager:

programs.helix = {
  settings.keys.normal = {
    C-p = {
      g = ":sh ${pkgs.procps}/bin/pkill go-grip || true; ${lib.getExe pkgs.go-grip} --theme dark %{buffer_name} > /dev/null || true";
    };
  };
};

Now if you press Ctrl+p followed by the g key, go-grip will open a tab in your browser so you can preview your Markdown file as you edit it!

Note that by preventing non-zero exit codes via || true, you avoid seeing error messages inside of Helix. This is necessary for both the pkill command and the go-grip command because:

1. pkill returns an exit code of 1 if there's no go-grip process currently running
2. go-grip returns an exit code of 1 when killed by pkill

Additionally by redirecting go-grip's stdout to /dev/null, you prevent Helix from showing a dialog box with the server URL, which seems unnecessary to me since go-grip launches a browser tab anyhow.