Cabal doesn't see happy on PATH about cabal HOT 3 OPEN

$ rm -rf ~/.cabal ~/.local/state/cabal ~/.cache/cabal
$ git clone https://github.com/haskell/happy.git 
# commit 78dcc03336d74822d58b8474e9639c6281c1a422
$ cd happy
cat<<EOF > ./default.nix
{ pkgs ? import <nixpkgs> {} }:
let
  inherit (pkgs) lib;
  hp = pkgs.haskell.packages.ghcHEAD;
  sourceRegexes = [
    "^src.*"
    "^exe.*"
    "^package.yaml"
    "^.*\\.cabal"
    "^LICENSE"
  ];

  shell = hp.shellFor {
    packages = p: [];
    shellHook = ''echo ok'';
    nativeBuildInputs = [ pkgs.cabal-install pkgs.happy ];
  };
in
{ inherit shell; }

EOF
$ nix-shell
$ type happy
happy is /nix/store/4z00pcvs075ghpnyhsvg6xg54kzncv5m-happy-1.20.1.1/bin/happy
$ cd packages/frontend # important step
$ cabal build
Warning: Unknown/unsupported 'ghc' version detected (Cabal 3.10.3.0 supports
'ghc' version < 9.10):
/nix/store/z3d4vkisfchw9ydyalax4q32pp5ry0dr-ghc-9.11.20240323/bin/ghc is
version 9.11.20240323
Build profile: -w ghc-9.11.20240323 -O1
In order, the following will be built (use -v for more details):
 - happy-frontend-2.0 (lib) (first run)
 - happy-3.0 (exe:happy) (first run)
Preprocessing library for happy-frontend-2.0..
Error: .cabal-wrapped: The program 'happy' is required but it could not be
found

Error: cabal: Failed to build happy-frontend-2.0 (which is required by
exe:happy from happy-3.0).