fzf: export environment variables to nushell

Pure Nushell sessions do not source hm-session-vars, so feed the same FZF_* values through programs.nushell.environmentVariables before sourcing fzf integration.

modules/programs/fzf.nix

@@ -273,6 +273,8 @@ in
     # fzf preserves the previous external completer and falls back to it
     # when its own completer does not apply.
     programs.nushell = lib.mkIf cfg.enableNushellIntegration {
+      environmentVariables = lib.mapAttrs (_n: toString) fzfEnvVars;
+
       extraConfig = mkAfter ''
         source ${
           pkgs.runCommand "nushell-fzf-integration.nu" { } ''

tests/modules/programs/fzf/default.nix

@@ -6,5 +6,6 @@
   fzf-fish-integration = ./fish-integration.nix;
   fzf-history-command-version-warning = ./history-command-version-warning.nix;
   fzf-nushell-integration = ./nushell-integration.nix;
+  fzf-nushell-history-command = ./nushell-history-command.nix;
   fzf-renamed-options = ./renamed-options.nix;
 }

tests/modules/programs/fzf/nushell-history-command.nix

@@ -0,0 +1,45 @@
+{ config, pkgs, ... }:
+
+{
+  programs.fzf = {
+    enable = true;
+    enableNushellIntegration = true;
+
+    historyWidget.command = "";
+
+    package = config.lib.test.mkStubPackage {
+      name = "fzf";
+      version = "0.73.0";
+      buildScript = ''
+        mkdir -p $out/bin
+        cat > $out/bin/fzf <<'EOF'
+        #!/bin/sh
+        echo "Stub fzf"
+        EOF
+        chmod +x $out/bin/fzf
+      '';
+    };
+  };
+
+  programs.nushell.enable = true;
+
+  nmt.script =
+    let
+      nushellConfigFile =
+        if pkgs.stdenv.isDarwin && !config.xdg.enable then
+          "home-files/Library/Application Support/nushell/config.nu"
+        else
+          "home-files/.config/nushell/config.nu";
+    in
+    ''
+      assertFileExists "${nushellConfigFile}"
+      assertFileContent "$(normalizeStorePaths "${nushellConfigFile}")" ${builtins.toFile "nushell-fzf-history-command-expected.nu" ''
+        load-env {
+            "FZF_CTRL_R_COMMAND": ""
+        }
+
+        source /nix/store/00000000000000000000000000000000-nushell-fzf-integration.nu
+
+      ''}
+    '';
+}