pinwheel: Add zsh prompts when in nix shell and/or direnv

hosts/pinwheel/modules/zsh/default.nix

@@ -54,6 +54,20 @@ in
           "bindkey -v '^?' backward-delete-char"
           "bindkey '^a' beginning-of-line"
           "bindkey '^e' end-of-line"
+          ''
+            function prompt_in_nix_shell() {
+              if [[ -n "$IN_NIX_SHELL" ]]; then
+                p10k segment -f yellow -t "nix";
+              fi
+            }
+          ''
+          ''
+            function prompt_in_direnv() {
+              if [[ -n "$DIRENV_DIR" ]]; then
+                p10k segment -f yellow -t "direnv"
+              fi
+            }
+          ''
         ];
       };
     };

hosts/pinwheel/modules/zsh/p10k-config/p10k.zsh

@@ -54,6 +54,8 @@
     command_execution_time    # previous command duration
     virtualenv                # python virtual environment
     prompt_char               # prompt symbol
+	in_nix_shell
+	in_direnv
   )
 
   # Right prompt segments.