I'm not sure how the "right" script is chosen in the first place.

I have this now:

[tool.poetry.scripts]
remarks = 'remarks.main:main'
remarks-server = "server:main"

And if I build with

poetryConfig = {
          projectDir = ./.;
          python = pkgs.python310;
          preferWheels = true;
          overrides = defaultPoetryOverrides.extend (final: prev: {
            click = prev.click.overridePythonAttrs (old: {
              buildInputs = (old.buildInputs or [ ]) ++ [ prev.flit-scm ];
            });
          });
          # Optional overrides if needed:
          # overrides = poetry2nix.overrides.withDefaults (final: prev: { });
        };

        remarksBin = mkPoetryApplication poetryConfig;
        remarksServer = mkPoetryApplication (poetryConfig // {
          extras = [ "server" ];
        });