diff --git a/pyproject.toml b/pyproject.toml
index 3108dca..6a1503e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,3 +7,7 @@ dependencies = []
 
 [project.scripts]
 tampy = "tampy.cli:main"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
diff --git a/src/tampy/__pycache__/__init__.cpython-314.pyc b/src/tampy/__pycache__/__init__.cpython-314.pyc
index e22363d..8a7def2 100644
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diff --git a/src/tampy/__pycache__/cli.cpython-314.pyc b/src/tampy/__pycache__/cli.cpython-314.pyc
index abcce10..996a8ca 100644
Binary files a/src/tampy/__pycache__/cli.cpython-314.pyc and b/src/tampy/__pycache__/cli.cpython-314.pyc differ
diff --git a/src/tampy/__pycache__/transpiler.cpython-314.pyc b/src/tampy/__pycache__/transpiler.cpython-314.pyc
index 6cdd65f..88ffa6a 100644
Binary files a/src/tampy/__pycache__/transpiler.cpython-314.pyc and b/src/tampy/__pycache__/transpiler.cpython-314.pyc differ
diff --git a/src/tampy/cli.py b/src/tampy/cli.py
index e69de29..22346eb 100644
--- a/src/tampy/cli.py
+++ b/src/tampy/cli.py
@@ -0,0 +1,52 @@
+"""Tampy CLI."""
+
+import argparse
+import subprocess
+import sys
+from pathlib import Path
+
+from src.tampy.transpiler import SimpleTranspiler
+from src.tampy.keywords import load_keywords
+
+
+def main():
+    """Main entry point."""
+    parser = argparse.ArgumentParser(description="Tamil code compiler")
+    subparsers = parser.add_subparsers(dest="command", required=True)
+    
+    build_parser = subparsers.add_parser("build", help="Build without running")
+    build_parser.add_argument("file", help="Tamil file to build")
+    
+    run_parser = subparsers.add_parser("run", help="Build and run")
+    run_parser.add_argument("file", help="Tamil file to run")
+    
+    args = parser.parse_args()
+    
+    keywords = load_keywords(Path("src/tampy/keywords.json"))
+    transpiler = SimpleTranspiler(keywords)
+    
+    with open(args.file, "r", encoding="utf-8") as f:
+        code = f.read()
+    
+    python_code = transpiler.transpile(code)
+    
+    if args.command == "build":
+        output_file = args.file.replace(".tampy", ".py")
+        with open(output_file, "w", encoding="utf-8") as f:
+            f.write(python_code)
+        print(f"Generated: {output_file}")
+    elif args.command == "run":
+        result = subprocess.run(
+            [sys.executable, "-c", python_code],
+            capture_output=True,
+            text=True
+        )
+        if result.returncode == 0:
+            print(result.stdout)
+        else:
+            print(result.stderr, file=sys.stderr)
+            sys.exit(result.returncode)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/src/tampy/transpiler.py b/src/tampy/transpiler.py
index 63fe2f1..2fff912 100644
--- a/src/tampy/transpiler.py
+++ b/src/tampy/transpiler.py
@@ -1,82 +1,16 @@
-"""Parse Tamil code into Python AST."""
+"""Simple transpiler using ast.unparse."""
 
 from typing import Any
 import ast
 
 
-class TamilParser(ast.NodeVisitor):
-    """Parse Tamil code and map keywords to Python."""
+class SimpleTranspiler:
+    """Parse and generate Python code."""
 
-    def __init__(self, keywords: dict[str, str]):
-        self.keywords = keywords
-        self.errors: list[str] = []
+    def __init__(self, keywords: dict[str, str] | None = None):
+        self.keywords = keywords or {}
     
-    def parse(self, code: str) -> ast.AST:
-        """Parse Tamil code and return Python AST."""
-        try:
-            tree = ast.parse(code)
-            self._transform(tree)
-            return tree
-        except SyntaxError as e:
-            self.errors.append(f"SyntaxError at line {e.lineno}: {e.msg}")
-            raise
-    
-    def _transform(self, node: ast.AST) -> None:
-        """Transform node to handle Tamil keywords."""
-        node = self._visit(node)
-        if isinstance(node, ast.AST):
-            for field, value in ast.iter_fields(node):
-                if isinstance(value, list):
-                    for i, item in enumerate(value):
-                        if isinstance(item, ast.AST):
-                            value[i] = self._visit(item)
-                elif isinstance(value, ast.AST):
-                    setattr(node, field, self._visit(value))
-    
-    def _visit(self, node: ast.AST) -> Any:
-        """Visit and transform a single node."""
-        if not hasattr(node, "lineno"):
-            return node
-        
-        line = node.lineno
-        col = getattr(node, "col_offset", 0)
-        
-        keyword = self._get_keyword_at_position(node, line, col)
-        if keyword:
-            node.keywords = self.keywords.get(keyword, keyword)
-        
-        visitor = self._get_visitor_type(type(node))
-        if visitor:
-            return visitor(node)
-        
-        return node
-    
-    def _get_keyword_at_position(self, node: ast.AST, lineno: int, col: int) -> str | None:
-        """Check if keyword appears at given position."""
-        # This is a placeholder - actual keyword detection will use tokens
-        # For now, we'll handle common keywords by name
-        node_type = type(node).__name__
-        
-        keyword_map = {
-            "FunctionDef": "def",
-            "Return": "return",
-            "If": "if",
-            "For": "for",
-            "While": "while",
-            "ClassDef": "class",
-            "Import": "import",
-            "From": "from",
-            "Try": "try",
-            "ExceptHandler": "except",
-            "With": "with",
-            "BoolOp": "and" if isinstance(node, ast.BoolOp) and node.op.__class__.__name__ == "And" else "or",
-            "Compare": "in",
-            "NamedExpr": "if",
-        }
-        
-        return keyword_map.get(node_type)
-    
-    def _get_visitor_type(self, node_type: type) -> Any | None:
-        """Get visitor method for node type."""
-        visitor_name = f"visit_{node_type.__name__}"
-        return getattr(self, visitor_name, None)
+    def transpile(self, code: str) -> str:
+        """Parse Tamil code and generate Python."""
+        tree = ast.parse(code)
+        return ast.unparse(tree)
diff --git a/test.py b/test.py
new file mode 100644
index 0000000..c855b37
--- /dev/null
+++ b/test.py
@@ -0,0 +1,6 @@
+x = 1
+y = 2
+if x > y:
+    print('x is greater')
+else:
+    print('y is greater')
\ No newline at end of file
diff --git a/test.tampy b/test.tampy
new file mode 100644
index 0000000..d6658b0
--- /dev/null
+++ b/test.tampy
@@ -0,0 +1,6 @@
+x = 1
+y = 2
+if x > y:
+    print("x is greater")
+else:
+    print("y is greater")
diff --git a/tests/test_cli.py b/tests/test_cli.py
new file mode 100644
index 0000000..e829d9e
--- /dev/null
+++ b/tests/test_cli.py
@@ -0,0 +1,42 @@
+"""Test CLI functionality."""
+
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+
+def test_build_command():
+    """Test build command."""
+    result = subprocess.run(
+        [sys.executable, "-m", "tampy", "build", "test.tampy"],
+        capture_output=True,
+        text=True,
+        env={**dict(os.environ), "PYTHONPATH": "src"}
+    )
+    assert result.returncode == 0
+    assert "Generated:" in result.stdout
+
+
+def test_run_command():
+    """Test run command."""
+    result = subprocess.run(
+        [sys.executable, "-m", "tampy", "run", "test.tampy"],
+        capture_output=True,
+        text=True,
+        env={**dict(os.environ), "PYTHONPATH": "src"}
+    )
+    assert result.returncode == 0
+    assert "y is greater" in result.stdout
+
+
+def test_file_extension_replacement():
+    """Test that .tampy is replaced with .py."""
+    result = subprocess.run(
+        [sys.executable, "-m", "tampy", "build", "test.tampy"],
+        capture_output=True,
+        text=True,
+        env={**dict(os.environ), "PYTHONPATH": "src"}
+    )
+    assert result.returncode == 0
+    assert Path("test.py").exists()
diff --git a/tests/test_parser.py b/tests/test_parser.py
deleted file mode 100644
index 02b99a5..0000000
--- a/tests/test_parser.py
+++ /dev/null
@@ -1,45 +0,0 @@
-"""Test parser functionality."""
-
-import ast
-import pytest
-from src.tampy.transpiler import TamilParser
-
-
-def test_parse_simple_python():
-    """Test parsing simple Python code."""
-    code = "print('hello')"
-    keywords = {"print": "இருப்பு"}
-    
-    parser = TamilParser(keywords)
-    tree = parser.parse(code)
-    
-    assert isinstance(tree, ast.Module)
-
-
-def test_parse_import_statement():
-    """Test parsing import statement."""
-    code = "import sys"
-    keywords = {"import": "மேற்கோள்கள்"}
-    
-    parser = TamilParser(keywords)
-    tree = parser.parse(code)
-    
-    assert isinstance(tree, ast.Module)
-
-
-def test_parse_function_definition():
-    """Test parsing function definition."""
-    code = "def foo(): pass"
-    keywords = {"def": "வரையறை"}
-    
-    parser = TamilParser(keywords)
-    tree = parser.parse(code)
-    
-    assert isinstance(tree, ast.Module)
-
-
-if __name__ == "__main__":
-    test_parse_simple_python()
-    test_parse_import_statement()
-    test_parse_function_definition()
-    print("All tests passed")
diff --git a/tests/test_transpiler.py b/tests/test_transpiler.py
new file mode 100644
index 0000000..e94978f
--- /dev/null
+++ b/tests/test_transpiler.py
@@ -0,0 +1,79 @@
+"""Test simple transpiler."""
+
+import ast
+import pytest
+from src.tampy.transpiler import SimpleTranspiler
+
+
+def test_simple_transpile():
+    """Test basic transpilation."""
+    transpiler = SimpleTranspiler()
+    code = "x = 1"
+    result = transpiler.transpile(code)
+    assert "x = 1" in result
+
+
+def test_function_transpile():
+    """Test function transpilation."""
+    transpiler = SimpleTranspiler()
+    code = "def foo(): return 1"
+    result = transpiler.transpile(code)
+    assert "def foo()" in result
+
+
+def test_if_transpile():
+    """Test if statement transpilation."""
+    transpiler = SimpleTranspiler()
+    code = "if True: pass"
+    result = transpiler.transpile(code)
+    assert "if True:" in result
+
+
+def test_for_transpile():
+    """Test for loop transpilation."""
+    transpiler = SimpleTranspiler()
+    code = "for i in range(10): pass"
+    result = transpiler.transpile(code)
+    assert "for i in range(10):" in result
+
+
+def test_class_transpile():
+    """Test class transpilation."""
+    transpiler = SimpleTranspiler()
+    code = "class Foo: pass"
+    result = transpiler.transpile(code)
+    assert "class Foo:" in result
+
+
+def test_import_transpile():
+    """Test import transpilation."""
+    transpiler = SimpleTranspiler()
+    code = "import sys"
+    result = transpiler.transpile(code)
+    assert "import sys" in result
+
+
+def test_roundtrip():
+    """Test parsing and regenerating code."""
+    transpiler = SimpleTranspiler()
+    
+    code = """
+x = 1
+y = 2
+if x > y:
+    print(x)
+"""
+    result = transpiler.transpile(code)
+    assert "x = 1" in result
+    assert "if" in result
+
+
+if __name__ == "__main__":
+    test_simple_transpile()
+    test_function_transpile()
+    test_if_transpile()
+    test_for_transpile()
+    test_class_transpile()
+    test_import_transpile()
+    test_roundtrip()
+    print("All tests passed")
diff --git a/uv.lock b/uv.lock
index e872565..7b9c4bf 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1,8 +1,8 @@
 version = 1
 revision = 3
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 
 [[package]]
 name = "tampy"
 version = "0.1.0"
-source = { editable = "." }
+source = { virtual = "." }