diff --git a/src/headers/common/helperFunctions/HelperFunctions.h b/src/headers/common/helperFunctions/HelperFunctions.h
index fac652d..f3133d3 100644
--- a/src/headers/common/helperFunctions/HelperFunctions.h
+++ b/src/headers/common/helperFunctions/HelperFunctions.h
@@ -3,6 +3,7 @@
 #include <iostream>
 #include <vector>
 #include <bitset>
+#include <cctype>
 
 inline std::vector<std::string> splitString(const std::string& input, const std::string& delimiter) {
     std::vector<std::string> tokens;
@@ -56,9 +57,9 @@ inline bool isHexDigit(char c) {
     return (std::isdigit(c) || (std::isxdigit(c) && std::islower(c)));
 }
 
-inline u_long binaryStringToLong(const std::string& binaryString) {
+inline unsigned long long binaryStringToLong(const std::string& binaryString) {
     std::string binaryDigits = binaryString.substr(2);  // Remove the '0b' prefix
-    u_long result = 0;
+    unsigned long long result = 0;
     for (char ch : binaryDigits) {
         result <<= 1;
         result += (ch - '0');
diff --git a/src/headers/parsing/Lexer.h b/src/headers/parsing/Lexer.h
index 59e98da..4f6fcf6 100644
--- a/src/headers/parsing/Lexer.h
+++ b/src/headers/parsing/Lexer.h
@@ -22,7 +22,7 @@ enum TokenType{
     // Increment/decrement operators
     PLUS_PLUS, MINUS_MINUS,
 
-    IDENTIFIER, STRING, NUMBER, BOOL,
+    IDENTIFIER, STRING, NUMBER, KW_BOOL,
 
     AND, OR, TRUE, FALSE, IF, ELSE, FUNCTION, FOR,
     WHILE, DO, VAR, CLASS, EXTENDS, EXTENSION, SUPER, THIS, NONE, RETURN, BREAK, CONTINUE,
@@ -53,7 +53,7 @@ inline std::string enum_mapping[] = {"OPEN_PAREN", "CLOSE_PAREN", "OPEN_BRACE",
                            
                            "PLUS_PLUS", "MINUS_MINUS",
 
-                           "IDENTIFIER", "STRING", "NUMBER", "BOOL",
+                           "IDENTIFIER", "STRING", "NUMBER", "KW_BOOL",
 
                            "AND", "OR", "TRUE", "FALSE", "IF", "ELSE", "FUNCTION", "FOR",
                            "WHILE", "DO", "VAR", "CLASS", "EXTENDS", "EXTENSION", "SUPER", "THIS", "NONE", "RETURN", "BREAK", "CONTINUE",
diff --git a/src/headers/runtime/Interpreter.h b/src/headers/runtime/Interpreter.h
index 85082f5..1bf50c3 100644
--- a/src/headers/runtime/Interpreter.h
+++ b/src/headers/runtime/Interpreter.h
@@ -74,6 +74,8 @@ private:
     std::unordered_map<std::string, std::unordered_map<std::string, std::shared_ptr<Function>>> builtinExtensions; // keys: "string","array","dict","any"
     std::unordered_map<std::string, std::string> classParents; // child -> parent
     std::unordered_map<std::string, std::unordered_map<std::string, Value>> classTemplates; // className -> template dict
+    // Field initializers per class in source order (to evaluate across inheritance chain)
+    std::unordered_map<std::string, std::vector<std::pair<std::string, std::shared_ptr<Expr>>>> classFieldInitializers; // className -> [(field, expr)]
     ErrorReporter* errorReporter;
     bool inThunkExecution = false;
     
@@ -138,6 +140,12 @@ public:
     void setClassTemplate(const std::string& className, const std::unordered_map<std::string, Value>& tmpl);
     bool getClassTemplate(const std::string& className, std::unordered_map<std::string, Value>& out) const;
     std::unordered_map<std::string, Value> buildMergedTemplate(const std::string& className) const;
+    // Field initializer APIs
+    void setClassFieldInitializers(const std::string& className, const std::vector<std::pair<std::string, std::shared_ptr<Expr>>>& inits) { classFieldInitializers[className] = inits; }
+    bool getClassFieldInitializers(const std::string& className, std::vector<std::pair<std::string, std::shared_ptr<Expr>>>& out) const {
+        auto it = classFieldInitializers.find(className);
+        if (it == classFieldInitializers.end()) return false; out = it->second; return true;
+    }
     void addStdLibFunctions();
     // Module APIs
     Value importModule(const std::string& spec, int line, int column); // returns module dict
diff --git a/src/headers/runtime/Value.h b/src/headers/runtime/Value.h
index 56f916b..f0e1449 100644
--- a/src/headers/runtime/Value.h
+++ b/src/headers/runtime/Value.h
@@ -3,6 +3,7 @@
 #include <string>
 #include <vector>
 #include <unordered_map>
+#include <memory>
 #include <utility>
 #include <cmath>
 #include <stdexcept>
diff --git a/src/sources/builtinModules/os.cpp b/src/sources/builtinModules/os.cpp
index 1c1bd69..c4c1928 100644
--- a/src/sources/builtinModules/os.cpp
+++ b/src/sources/builtinModules/os.cpp
@@ -4,9 +4,19 @@
 #include <vector>
 #include <string>
 #include <filesystem>
-#include <unistd.h>
-#include <sys/types.h>
-#include <dirent.h>
+#if defined(_WIN32)
+  #include <windows.h>
+  #include <direct.h>
+  #include <limits.h>
+  #include <io.h>
+  #ifndef PATH_MAX
+    #define PATH_MAX MAX_PATH
+  #endif
+#else
+  #include <unistd.h>
+  #include <sys/types.h>
+  #include <dirent.h>
+#endif
 
 namespace fs = std::filesystem;
 
@@ -15,19 +25,35 @@ void registerOsModule(Interpreter& interpreter) {
         // Process
         m.fn("getcwd", [](std::vector<Value>, int, int) -> Value {
             char buf[PATH_MAX];
+            #if defined(_WIN32)
+            if (_getcwd(buf, sizeof(buf))) return Value(std::string(buf));
+            #else
             if (getcwd(buf, sizeof(buf))) return Value(std::string(buf));
+            #endif
             return NONE_VALUE;
         });
         m.fn("chdir", [](std::vector<Value> a, int, int) -> Value {
             if (a.size() != 1 || !a[0].isString()) return Value(false);
+            #if defined(_WIN32)
+            int rc = ::_chdir(a[0].asString().c_str());
+            #else
             int rc = ::chdir(a[0].asString().c_str());
+            #endif
             return Value(rc == 0);
         });
         m.fn("getpid", [](std::vector<Value>, int, int) -> Value {
+            #if defined(_WIN32)
+            return Value(static_cast<double>(GetCurrentProcessId()));
+            #else
             return Value(static_cast<double>(getpid()));
+            #endif
         });
         m.fn("getppid", [](std::vector<Value>, int, int) -> Value {
+            #if defined(_WIN32)
+            return NONE_VALUE; // not directly available; could use Toolhelp32Snapshot if needed
+            #else
             return Value(static_cast<double>(getppid()));
+            #endif
         });
         m.fn("name", [](std::vector<Value>, int, int) -> Value {
 #if defined(_WIN32)
diff --git a/src/sources/builtinModules/path.cpp b/src/sources/builtinModules/path.cpp
index bdb5eb9..4315ef9 100644
--- a/src/sources/builtinModules/path.cpp
+++ b/src/sources/builtinModules/path.cpp
@@ -1,6 +1,7 @@
 #include "path_module.h"
 #include "Interpreter.h"
 #include <filesystem>
+#include <cctype>
 
 namespace fs = std::filesystem;
 
@@ -11,6 +12,17 @@ static std::string join_impl(const std::vector<Value>& parts){
     return p.generic_string();
 }
 
+static bool isabs_impl(const std::string& s) {
+#if defined(_WIN32)
+    if (s.size() >= 2 && (s[0] == '/' || s[0] == '\\')) return true; // root-relative on current drive
+    if (s.rfind("\\\\", 0) == 0) return true; // UNC path
+    if (s.size() >= 3 && std::isalpha(static_cast<unsigned char>(s[0])) && s[1] == ':' && (s[2] == '/' || s[2] == '\\')) return true; // C:\ or C:/
+    return false;
+#else
+    return !s.empty() && s[0] == '/';
+#endif
+}
+
 void registerPathModule(Interpreter& interpreter) {
     interpreter.registerModule("path", [](Interpreter::ModuleBuilder& m) {
         m.fn("join", [](std::vector<Value> a, int, int) -> Value {
@@ -37,7 +49,7 @@ void registerPathModule(Interpreter& interpreter) {
         });
         m.fn("isabs", [](std::vector<Value> a, int, int) -> Value {
             if (a.size()!=1 || !a[0].isString()) return Value(false);
-            return Value(fs::path(a[0].asString()).is_absolute());
+            return Value(isabs_impl(a[0].asString()));
         });
         m.fn("relpath", [](std::vector<Value> a, int, int) -> Value {
             if (a.size()<1 || a.size()>2 || !a[0].isString() || (a.size()==2 && !a[1].isString())) return NONE_VALUE;
diff --git a/src/sources/builtinModules/sys.cpp b/src/sources/builtinModules/sys.cpp
index a546ead..6d3651b 100644
--- a/src/sources/builtinModules/sys.cpp
+++ b/src/sources/builtinModules/sys.cpp
@@ -2,7 +2,11 @@
 #include "Interpreter.h"
 #include "Environment.h"
 #include "Lexer.h" // for Token and IDENTIFIER
-#include <unistd.h>
+#if defined(_WIN32)
+  #include <windows.h>
+#else
+  #include <unistd.h>
+#endif
 #include <limits.h>
 #include <cstdlib>
 #include <cstring>
diff --git a/src/sources/runtime/Evaluator.cpp b/src/sources/runtime/Evaluator.cpp
index 738d8ce..4c563ab 100644
--- a/src/sources/runtime/Evaluator.cpp
+++ b/src/sources/runtime/Evaluator.cpp
@@ -111,8 +111,23 @@ Value Evaluator::visitBinaryExpr(const std::shared_ptr<BinaryExpr>& expression)
             case PLUS: return left + right;
             case MINUS: return left - right;
             case STAR: return left * right;
-            case SLASH: return left / right;
-            case PERCENT: return left % right;
+            case SLASH: {
+                if (right.isNumber() && right.asNumber() == 0.0) {
+                    // Report precise site for division by zero
+                    interpreter->reportError(expression->oper.line, expression->oper.column,
+                                             "Runtime Error", "Division by zero", "/");
+                    throw std::runtime_error("Division by zero");
+                }
+                return left / right;
+            }
+            case PERCENT: {
+                if (right.isNumber() && right.asNumber() == 0.0) {
+                    interpreter->reportError(expression->oper.line, expression->oper.column,
+                                             "Runtime Error", "Modulo by zero", "%");
+                    throw std::runtime_error("Modulo by zero");
+                }
+                return left % right;
+            }
             case BIN_AND: return left & right;
             case BIN_OR: return left | right;
             case BIN_XOR: return left ^ right;
diff --git a/src/sources/runtime/Executor.cpp b/src/sources/runtime/Executor.cpp
index 9143587..ae497a7 100644
--- a/src/sources/runtime/Executor.cpp
+++ b/src/sources/runtime/Executor.cpp
@@ -391,11 +391,11 @@ void Executor::visitClassStmt(const std::shared_ptr<ClassStmt>& statement, Execu
     } else {
         interpreter->registerClass(statement->name.lexeme, "");
     }
-    // Predefine fields as none, keep initializers mapped
-    std::unordered_map<std::string, std::shared_ptr<Expr>> fieldInitializers;
+    // Predefine fields as none, capture this class's field initializers, and register them for inheritance evaluation
+    std::vector<std::pair<std::string, std::shared_ptr<Expr>>> fieldInitializers;
     for (const auto& f : statement->fields) {
         classDict[f.name.lexeme] = NONE_VALUE;
-        fieldInitializers[f.name.lexeme] = f.initializer;
+        fieldInitializers.emplace_back(f.name.lexeme, f.initializer);
     }
 
     // Attach methods as functions closed over a prototype env
@@ -411,6 +411,8 @@ void Executor::visitClassStmt(const std::shared_ptr<ClassStmt>& statement, Execu
 
     // Save template to interpreter so instances can include inherited fields/methods
     interpreter->setClassTemplate(statement->name.lexeme, classDict);
+    // Register field initializers for this class
+    interpreter->setClassFieldInitializers(statement->name.lexeme, fieldInitializers);
 
     // Define a constructor function Name(...) that builds an instance dict
     auto ctorName = statement->name.lexeme;
@@ -422,17 +424,31 @@ void Executor::visitClassStmt(const std::shared_ptr<ClassStmt>& statement, Execu
         for (const auto& kv : tmpl) dictRef[kv.first] = kv.second;
         // Tag instance with class name for extension lookup
         dictRef["__class"] = Value(className);
-        // Evaluate field initializers with this bound
-        if (!fieldInitializers.empty()) {
+        // Evaluate field initializers across inheritance chain (parent-to-child order)
+        {
+            // Build chain from base to current
+            std::vector<std::string> chain;
+            std::string cur = className;
+            while (!cur.empty()) { chain.push_back(cur); cur = runtime->getParentClass(cur); }
+            std::reverse(chain.begin(), chain.end());
             auto saved = runtime->getEnvironment();
             auto env = std::make_shared<Environment>(saved);
             env->setErrorReporter(nullptr);
             env->define("this", instance);
             runtime->setEnvironment(env);
-            for (const auto& kv : fieldInitializers) {
-                if (kv.second) {
-                    Value v = runtime->evaluate(kv.second);
-                    dictRef[kv.first] = v;
+            for (const auto& cls : chain) {
+                std::vector<std::pair<std::string, std::shared_ptr<Expr>>> inits;
+                if (runtime->getClassFieldInitializers(cls, inits)) {
+                    for (const auto& kv : inits) {
+                        const std::string& fieldName = kv.first;
+                        const auto& expr = kv.second;
+                        if (expr) {
+                            Value v = runtime->evaluate(expr);
+                            dictRef[fieldName] = v;
+                            // Expose field names as locals for subsequent initializers
+                            env->define(fieldName, v);
+                        }
+                    }
                 }
             }
             runtime->setEnvironment(saved);
@@ -445,6 +461,10 @@ void Executor::visitClassStmt(const std::shared_ptr<ClassStmt>& statement, Execu
             std::shared_ptr<Environment> newEnv = std::make_shared<Environment>(fn->closure);
             newEnv->setErrorReporter(nullptr);
             newEnv->define("this", instance);
+            // Seed current class for proper super resolution within init
+            if (fn && !fn->ownerClass.empty()) {
+                newEnv->define("__currentClass", Value(fn->ownerClass));
+            }
             // Bind params
             size_t n = std::min(fn->params.size(), args.size());
             for (size_t i = 0; i < n; ++i) {
diff --git a/src/sources/runtime/Interpreter.cpp b/src/sources/runtime/Interpreter.cpp
index 2fc44fe..e0a2a1f 100644
--- a/src/sources/runtime/Interpreter.cpp
+++ b/src/sources/runtime/Interpreter.cpp
@@ -8,7 +8,11 @@
 #include "Expression.h"
 #include "Parser.h"
 #include <filesystem>
-#include <unistd.h>
+#if defined(_WIN32)
+  #include <direct.h>
+#else
+  #include <unistd.h>
+#endif
 #include <fstream>
 #include <iostream>