diff --git a/src/autoscript/ASEngine.py b/src/autoscript/ASEngine.py
index f73657b..352f4a8 100644
--- a/src/autoscript/ASEngine.py
+++ b/src/autoscript/ASEngine.py
@@ -33,7 +33,7 @@ from .ASTokenizer import (
 )
 
 
-__all__ = ["execute", "addTargetVar"]
+__all__ = ["execute", "addTargetVar", "splitTopLevel"]
 
 
 # Engine state
@@ -69,7 +69,7 @@ _RE_CUR_DATE_OFFSET = re.compile(r"^CURRENT_DATE\s*\+\s*(\d+)$", re.IGNORECASE)
 _RE_CUR_TIME_OFFSET = re.compile(r"^CURRENT_TIME\s*\+\s*(\d+)$", re.IGNORECASE)
 
 
-def _splitTopLevel(
+def splitTopLevel(
     text: str,
     delimiter: str
 ) -> list:
@@ -281,13 +281,13 @@ def _evaluateCondition(
     s = condition_str.strip()
     if not s:
         return False
-    or_parts = _splitTopLevel(s, ".OR.")
+    or_parts = splitTopLevel(s, ".OR.")
     if len(or_parts) > 1:
         return any(
             _evaluateCondition(p.strip(), target_data, line)
             for p in or_parts
         )
-    and_parts = _splitTopLevel(s, ".AND.")
+    and_parts = splitTopLevel(s, ".AND.")
     if len(and_parts) > 1:
         return all(
             _evaluateCondition(p.strip(), target_data, line)
@@ -466,12 +466,14 @@ class _EngineExecutor(NodeVisitor):
 
         return self._cur_line
 
+
     def _incLine(
         self
     ):
 
         self._cur_line += 1
 
+
     def visitScript(
         self,
         _node: Script
@@ -480,6 +482,7 @@ class _EngineExecutor(NodeVisitor):
         for child in _node.body:
             child.accept(self)
 
+
     def visitIf(
         self,
         _node: IfNode
@@ -506,6 +509,7 @@ class _EngineExecutor(NodeVisitor):
                 for child in _node.else_body:
                     child.accept(self)
 
+
     def visitSet(
         self,
         _node: SetNode
@@ -515,6 +519,7 @@ class _EngineExecutor(NodeVisitor):
         full_line = f"SET {_node.target} = {_node.value}"
         _executeSet(full_line, self._target_data, self._line)
 
+
     def visitOp(
         self,
         _node: OpNode
@@ -525,6 +530,7 @@ class _EngineExecutor(NodeVisitor):
         full_line = f"{_node.target} .{op_upper}. {_node.value}"
         _executeOperation(full_line, self._target_data, self._line)
 
+
     def visitPass(
         self,
         _node: PassNode
@@ -532,6 +538,7 @@ class _EngineExecutor(NodeVisitor):
 
         self._incLine()
 
+
     def visitUnrecog(
         self,
         _node: UnrecogNode
diff --git a/src/autoscript/ASOperator.py b/src/autoscript/ASOperator.py
index 49facd7..60d6195 100644
--- a/src/autoscript/ASOperator.py
+++ b/src/autoscript/ASOperator.py
@@ -17,7 +17,7 @@ from datetime import (
 from .ASObject import ASObject
 
 
-__all__ = ["ASOperator"]
+__all__ = ["ASOperator", "ARITH_TYPES", "COMPARISON_OPERATORS"]
 
 
 class ASOperator:
@@ -96,12 +96,11 @@ class ASOperator:
         target_val = target.getValue(target_data)
         if target_val is None:
             raise ValueError(f"'{target.name}' 的值为空，无法进行运算")
-        if op == ".ADD.":
-            cls._arithAdd(target, target_val, operand, target_data)
-        elif op == ".SUB.":
-            cls._arithSub(target, target_val, operand, target_data)
-        else:
+        op_name = "ADD" if op == ".ADD." else "SUB" if op == ".SUB." else None
+        if op_name is None:
             raise ValueError(f"不支持的操作 '{op}'")
+        sign = 1 if op == ".ADD." else -1
+        cls._arithBinary(target, target_val, operand, target_data, sign, op_name)
 
     @classmethod
     def _arithBinary(
@@ -110,13 +109,13 @@ class ASOperator:
         target_val,
         operand: ASObject,
         target_data: dict,
-        sign: int
+        sign: int,
+        op_name: str = ""
     ):
-        """Apply ADD (sign=1) or SUB (sign=-1) per type."""
+        """Apply arithmetic per type."""
 
         tp = target.var_type
         raw_op = operand._value
-        op_name = "ADD" if sign == 1 else "SUB"
 
         if tp == "Date":
             if not isinstance(target_val, date):
@@ -129,35 +128,13 @@ class ASOperator:
             dt = datetime.combine(datetime.today(), target_val) + delta
             new_val = dt.time()
         elif tp == "Int":
-            new_val = int(target_val) + int(raw_op) * sign
+            new_val = int(target_val) + int(raw_op)*sign
         elif tp == "Float":
-            new_val = float(target_val) + float(raw_op) * sign
+            new_val = float(target_val) + float(raw_op)*sign
         else:
             raise ValueError(f"'{tp}' 类型不支持 {op_name} 操作")
         target.setValue(new_val, target_data)
 
-    @classmethod
-    def _arithAdd(
-        cls,
-        target: ASObject,
-        target_val,
-        operand: ASObject,
-        target_data: dict
-    ):
-        """Dispatch ADD per type."""
-        cls._arithBinary(target, target_val, operand, target_data, 1)
-
-    @classmethod
-    def _arithSub(
-        cls,
-        target: ASObject,
-        target_val,
-        operand: ASObject,
-        target_data: dict
-    ):
-        """Dispatch SUB per type."""
-        cls._arithBinary(target, target_val, operand, target_data, -1)
-
     @classmethod
     def compare(
         cls,
@@ -206,3 +183,9 @@ class ASOperator:
                 f"无法比较 '{left.name}' ({left.var_type}) "
                 f"与 '{right.name}' ({right.var_type})"
             )
+
+
+# Public constants
+# may be used by the GUI orchestration dialog.
+ARITH_TYPES = ASOperator._ARITH_TYPES
+COMPARISON_OPERATORS = set(ASOperator._COMPARE.keys())
diff --git a/src/autoscript/__init__.py b/src/autoscript/__init__.py
index c761e6d..c570fe5 100644
--- a/src/autoscript/__init__.py
+++ b/src/autoscript/__init__.py
@@ -14,13 +14,16 @@ from autoscript.ASTokenizer import (
 from autoscript.ASEngine import (
     execute,
     addTargetVar,
+    splitTopLevel,
 )
 from autoscript.ASObject import _META_VARS as META_VARS
 from autoscript.ASObserver import ParsingObserver
 
+
 __all__ = [
     "execute",
     "addTargetVar",
+    "splitTopLevel",
     "registerDefaultTargetVars",
     "buildMockTargetData",
     "META_VARS",
@@ -35,18 +38,6 @@ __all__ = [
     "ParsingObserver",
 ]
 
-# All variables available to scripts (display_name -> (name, type)).
-# This mirrors the old AutoScriptEngine.VARIABLE_META for backward
-# compatibility in the UI orchestration dialog.
-ALL_VARIABLES: dict = {
-    "用户名": ("USERNAME", "String"),
-    "用户启用": ("USER_ENABLE", "Boolean"),
-    "预约日期": ("RESERVE_DATE", "Date"),
-    "预约开始时间": ("RESERVE_BEGIN_TIME", "Time"),
-    "预约结束时间": ("RESERVE_END_TIME", "Time"),
-    "当前时间": ("CURRENT_TIME", "Time"),
-    "当前日期": ("CURRENT_DATE", "Date"),
-}
 
 # Key paths into target_data dict for each target variable.
 # (name, type, key_path, display_name)
@@ -57,6 +48,15 @@ _TARGET_VAR_DEFS = [
     ("RESERVE_BEGIN_TIME", "Time",  ["reserve_info", "begin_time", "time"], "预约开始时间"),
     ("RESERVE_END_TIME",   "Time",  ["reserve_info", "end_time",   "time"], "预约结束时间"),
 ]
+
+# All variables (display_name -> (name, type)), derived from target vars + meta vars.
+ALL_VARIABLES = {
+    display_name: (name, var_type)
+    for name, var_type, _, display_name in _TARGET_VAR_DEFS
+} | {
+    obj.display_name: (obj.name, obj.var_type)
+    for obj in META_VARS.values()
+}
 _MOCK_TYPE_VALUES = {
     "String": "__mock__",
     "Boolean": True,