zsh: fix lib function for env var path parsing

Allow env variables to be used and avoid mangling path.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

modules/programs/zsh/history.nix

@@ -9,7 +9,7 @@ let
 
   inherit (lib) literalExpression mkOption types;
 
-  inherit (import ./lib.nix { inherit config lib; }) dotDirAbs mkAbsPathStr;
+  inherit (import ./lib.nix { inherit config lib; }) dotDirAbs mkShellVarPathStr;
 in
 {
   options =
@@ -180,7 +180,7 @@ in
         ${lib.optionalString (
           cfg.history.ignorePatterns != [ ]
         ) "HISTORY_IGNORE=${lib.escapeShellArg "(${lib.concatStringsSep "|" cfg.history.ignorePatterns})"}"}
-        HISTFILE="${mkAbsPathStr cfg.history.path}"
+        HISTFILE="${mkShellVarPathStr cfg.history.path}"
         mkdir -p "$(dirname "$HISTFILE")"
 
         setopt HIST_FCNTL_LOCK

modules/programs/zsh/lib.nix

@@ -33,6 +33,20 @@ rec {
   mkAbsPathStr =
     pathStr: cleanPathStr ((lib.optionalString (!lib.hasPrefix "/" pathStr) "${homeDir}/") + pathStr);
 
+  # For shell variable paths like history.path that get expanded at runtime
+  mkShellVarPathStr =
+    pathStr:
+    let
+      cleanPath = lib.removeSuffix "/" pathStr;
+      hasShellVars = lib.hasInfix "$" cleanPath;
+    in
+    if hasShellVars then
+      # Does not escape shell variables, allowing them to be expanded at runtime
+      cleanPath
+    else
+      # For literal paths, make them absolute if needed and escape them
+      cleanPathStr ((lib.optionalString (!lib.hasPrefix "/" cleanPath) "${homeDir}/") + cleanPath);
+
   dotDirAbs = mkAbsPathStr cfg.dotDir;
   dotDirRel = mkRelPathStr cfg.dotDir;