Add mark_prompt_start function for fish

It is for something foot uses, see
https://codeberg.org/dnkl/foot/wiki#user-content-jumping-between-prompts for
more info

home-manager/modules/fish/default.nix

@@ -14,7 +14,7 @@ in
   config = mkIf cfg.enable {
     programs.fish = {
       enable = true;
-      functions = import ./functions.nix { inherit (pkgs) git; };
+      functions = import ./functions.nix { inherit (pkgs) git coreutils; };
 
       plugins = [
         {

home-manager/modules/fish/functions.nix

@@ -1,4 +1,10 @@
-{ git }: {
+{ git, coreutils }: {
+  mark_prompt_start = {
+    onEvent = "fish_prompt";
+    body = ''
+      ${coreutils}/bin/echo -en "\e]133;A\e\\"
+    '';
+  };
   reload = {
     body = ''
       history --save
@@ -22,19 +28,19 @@
       set files (${git}/bin/git diff --diff-filter=ACMR --name-only $argv[1])
       set repo_path (realpath --relative-to=$PWD (${git}/bin/git rev-parse --show-toplevel))
       set clangformat (${git}/bin/git config --get clangFormat.binary)
-      echo "Formatting files in $repo_path with $clangformat"
+      ${coreutils}/bin/echo "Formatting files in $repo_path with $clangformat"
 
       for f in $files
         set file (realpath $repo_path/$f)
-        echo "Processing $file"
+        ${coreutils}/bin/echo "Processing $file"
 
         set ext (string match -r ".*\.([^\.]+)\$" $file)[2]
 
         if contains $ext $source_exts
-          echo "Formatting $file"
+          ${coreutils}/bin/echo "Formatting $file"
           $clangformat -i -style=file $file
         else
-          echo "Extension $ext not found in $source_exts"
+          ${coreutils}/bin/echo "Extension $ext not found in $source_exts"
         end
       end
     '';
@@ -47,19 +53,19 @@
         set libcomponents (string split "." "$lib")
         set libname $libcomponents[1].$libcomponents[2]
         set libmajor $libname.$libcomponents[3]
-  
+
         if test -f $libname -o -L $libname
-          echo "$libname already exists"
+          ${coreutils}/bin/echo "$libname already exists"
           return 1
         end
 
         if test -f $libmajor -o -L $libmajor
-          echo "$libmajor already exists"
+          ${coreutils}/bin/echo "$libmajor already exists"
           return 2
         end
 
-        ln -s $lib $libmajor
-        ln -s $libmajor $libname
+        ${coreutils}/bin/ln -s $lib $libmajor
+        ${coreutils}/bin/ln -s $libmajor $libname
       end
     '';
   };