diff --git a/extract.py b/extract.py
index b47e15c..2f0dc63 100644
--- a/extract.py
+++ b/extract.py
@@ -1,4 +1,9 @@
 #!/usr/bin/env python3
+"""
+Analysiert __register__-Methoden in Tryton-Modulen und extrahiert alle
+Datenbank-Operationen (Spalten-/Tabellen-Änderungen, execute/insert/update/...),
+die dort ausgeführt werden. Ergebnis wird pro Modul als JSON abgelegt.
+"""
 
 import re
 import ast
@@ -6,6 +11,11 @@ import argparse
 import json
 from pathlib import Path
 
+
+# --------------------------------------------------------------------------
+# Konfiguration / Defaults
+# --------------------------------------------------------------------------
+
 DEFAULT_REPO = "/home/uha4/tmp/tryton"
 
 DEFAULT_MODULES = [
@@ -27,18 +37,84 @@ DEFAULT_MODULES = [
 
 DEFAULT_OUTPUT = "data"
 
+# Operationen, die find_tables() als "hier wird eine Tabelle referenziert"
+# erkennt (inkl. table_exist, das selbst keine Änderung ist, aber die
+# betroffene Tabelle offenlegt).
+TABLE_REFERENCE_OPS = {
+    "column_rename",
+    "drop_column",
+    "add_column",
+    "drop_constraint",
+    "add_constraint",
+    "not_null_action",
+    "index_action",
+    "alter_size",
+    "update",
+    "insert",
+    "delete",
+    "select",
+    "table_exist",
+}
+
+# Operationen, die extract_call() tatsächlich als DB-Operation aufnimmt.
+# execute/executemany kommen hier zusätzlich dazu, table_exist bewusst nicht
+# (das ist nur eine Existenzprüfung, keine Änderung).
+INTERESTING_OPS = {
+    "column_rename",
+    "drop_column",
+    "add_column",
+    "drop_constraint",
+    "add_constraint",
+    "not_null_action",
+    "index_action",
+    "alter_size",
+    "execute",
+    "executemany",
+    "update",
+    "insert",
+    "delete",
+    "select",
+}
+
+
+# --------------------------------------------------------------------------
+# AST-Visitor
+# --------------------------------------------------------------------------
+
 class RegisterExtractor(ast.NodeVisitor):
+    """
+    Läuft über eine Python-Datei und sammelt für jede __register__-Methode
+    die darin ausgeführten DB-Operationen (vor/nach dem super()-Aufruf,
+    inkl. eventueller if-Bedingung).
+    """
 
     def __init__(self, source, module, filename):
         self.module = module
         self.filename = filename
         self.source = source
+
         self.results = []
+
+        # Name der Model-Klasse -> __name__ (z. B. "MyClass" -> "ir.model.data")
         self.model_names = {}
+
+        # Innerhalb der aktuell analysierten __register__-Methode:
+        # lokale Variable -> Tabellenname
         self.table_vars = {}
+
+        # lokale Variable -> Quelltext-Ausdruck, aus dem sie stammt
+        # (für die spätere Ersetzung im "code"-Feld der Operation)
         self.alias_vars = {}
 
+        # Klasse, in der wir uns gerade befinden (für cls._table etc.)
+        self.current_class = None
+
+    # -- Modul-/Klassenebene ------------------------------------------------
+
     def visit_Module(self, node):
+        # Erst alle __name__-Zuweisungen einsammeln, damit sie beim
+        # eigentlichen Durchlauf schon bekannt sind (Reihenfolge der
+        # Klassen im File soll keine Rolle spielen).
         for item in node.body:
             if isinstance(item, ast.ClassDef):
                 model_name = self.get_model_name(item)
@@ -54,20 +130,41 @@ class RegisterExtractor(ast.NodeVisitor):
 
         self.generic_visit(node)
 
-    def extract_register(self, cls, func):
+    def get_model_name(self, node):
+        """Liest `__name__ = "some.model"` aus einem Klassenkörper."""
+        for item in node.body:
+            if not isinstance(item, ast.Assign):
+                continue
 
+            for target in item.targets:
+                if isinstance(target, ast.Name) and target.id == "__name__":
+                    try:
+                        return ast.literal_eval(item.value)
+                    except Exception:
+                        return None
+
+        return None
+
+    # -- __register__ selbst -------------------------------------------------
+
+    def extract_register(self, cls, func):
+        """Analysiert eine einzelne __register__-Methode."""
         operations = []
         self.table_vars = {}
+        self.alias_vars = {}
         self.current_class = cls
 
         model_name = self.model_names.get(cls)
         if model_name:
             self.table_vars["cls"] = model_name
 
+        # Tabellen-Variablen (z. B. `table = cls.__table__()`) vorab
+        # einsammeln, damit sie beim eigentlichen Walk schon aufgelöst
+        # werden können.
         for stmt in func.body:
             self.collect_table_assignment(stmt)
 
-        self.walk_statements(func.body, operations, "before_super", None)
+        self.walk_statements(func.body, operations, phase="before_super", condition=None)
 
         self.results.append({
             "module": self.module,
@@ -78,25 +175,14 @@ class RegisterExtractor(ast.NodeVisitor):
             "operations": operations,
         })
 
-
-    def get_model_name(self, node):
-        for item in node.body:
-            if not isinstance(item, ast.Assign):
-                continue
-
-            for target in item.targets:
-                if (
-                    isinstance(target, ast.Name)
-                    and target.id == "__name__"
-                ):
-                    try:
-                        return ast.literal_eval(item.value)
-                    except Exception:
-                        return None
-
-        return None
+    # -- Tabellen-Variablen auflösen -----------------------------------------
 
     def collect_table_assignment(self, stmt):
+        """
+        Sucht rekursiv nach Zuweisungen der Form `name = <table-ausdruck>`
+        und merkt sich in self.table_vars, welche Variable welche Tabelle
+        referenziert.
+        """
         for node in ast.walk(stmt):
             if not isinstance(node, ast.Assign):
                 continue
@@ -129,22 +215,19 @@ class RegisterExtractor(ast.NodeVisitor):
                 self.table_vars[target.id] = node.value.value
 
     def resolve_table_call(self, node):
+        """
+        Erkennt Aufrufe, die direkt eine Tabelle liefern:
+          - pool.get('some.model')
+          - X.__table__() / X.__table_handler__()
+        und gibt den zugehörigen (normalisierten) Tabellennamen zurück.
+        """
         if not isinstance(node, ast.Call):
             return None
 
         # ModelClass = pool.get('ir.model.data')
-        if (
-            isinstance(node.func, ast.Attribute)
-            and node.func.attr == "get"
-            and isinstance(node.func.value, ast.Name)
-            and node.func.value.id == "pool"
-            and len(node.args) == 1
-            and isinstance(node.args[0], ast.Constant)
-            and isinstance(node.args[0].value, str)
-        ):
+        if self._is_pool_get(node):
             return node.args[0].value
 
-
         if not (
             isinstance(node.func, ast.Attribute)
             and node.func.attr in ("__table__", "__table_handler__")
@@ -152,23 +235,11 @@ class RegisterExtractor(ast.NodeVisitor):
             return None
 
         receiver = node.func.value
-        # ModelClass = pool.get('ir.model.data')
-        if (
-            isinstance(receiver, ast.Name)
-            and receiver.id == "pool"
-        ):
+
+        # pool.__table__() o.ä. ergibt keinen sinnvollen Tabellennamen
+        if isinstance(receiver, ast.Name) and receiver.id == "pool":
             return None
 
-        if (
-            isinstance(node.func, ast.Attribute)
-            and node.func.attr == "get"
-            and isinstance(node.func.value, ast.Name)
-            and node.func.value.id == "pool"
-            and len(node.args) == 1
-            and isinstance(node.args[0], ast.Constant)
-            and isinstance(node.args[0].value, str)
-        ):
-            return node.args[0].value
         if isinstance(receiver, ast.Name):
             if receiver.id == "cls":
                 model_name = self.model_names.get(self.current_class)
@@ -177,16 +248,33 @@ class RegisterExtractor(ast.NodeVisitor):
                     self.model_names.get(receiver.id)
                     or self.table_vars.get(receiver.id)
                 )
-                
+
             if model_name:
                 return model_name.replace(".", "_")
 
         return None
 
+    @staticmethod
+    def _is_pool_get(node):
+        """True für Aufrufe der Form `pool.get('some.model')`."""
+        return (
+            isinstance(node.func, ast.Attribute)
+            and node.func.attr == "get"
+            and isinstance(node.func.value, ast.Name)
+            and node.func.value.id == "pool"
+            and len(node.args) == 1
+            and isinstance(node.args[0], ast.Constant)
+            and isinstance(node.args[0].value, str)
+        )
+
     def resolve_table_object(self, node):
+        """
+        Löst einen beliebigen Ausdruck (Variable, cls._table, Aufruf) zu
+        einem Tabellennamen auf, falls möglich.
+        """
         if isinstance(node, ast.Name):
             return self.table_vars.get(node.id)
-    
+
         if (
             isinstance(node, ast.Attribute)
             and node.attr == "_table"
@@ -196,10 +284,14 @@ class RegisterExtractor(ast.NodeVisitor):
             model_name = self.model_names.get(self.current_class)
             if model_name:
                 return model_name.replace(".", "_")
-    
+
         return self.resolve_table_call(node)
 
     def find_tables(self, node):
+        """
+        Sammelt alle Tabellen, die innerhalb eines Ausdrucks (typischerweise
+        eines Funktionsaufrufs) referenziert werden.
+        """
         tables = []
 
         for child in ast.walk(node):
@@ -208,46 +300,45 @@ class RegisterExtractor(ast.NodeVisitor):
 
             if not (
                 isinstance(child.func, ast.Attribute)
-                and child.func.attr in {
-                    "column_rename",
-                    "drop_column",
-                    "add_column",
-                    "drop_constraint",
-                    "add_constraint",
-                    "not_null_action",
-                    "index_action",
-                    "alter_size",
-                    "update",
-                    "insert",
-                    "delete",
-                    "select",
-                    "table_exist",
-                }
+                and child.func.attr in TABLE_REFERENCE_OPS
             ):
                 continue
-            
+
             # backend.TableHandler.table_exist(cls._table)
-            if (
-                isinstance(child.func.value, ast.Attribute)
-                and child.func.value.attr == "TableHandler"
-                and isinstance(child.func.value.value, ast.Name)
-                and child.func.value.value.id == "backend"
-                and child.func.attr == "table_exist"
-                and child.args
-            ):
+            if self._is_table_handler_call(child, attr="table_exist") and child.args:
                 table = self.resolve_table_object(child.args[0])
                 if table and table not in tables:
                     tables.append(table)
-    
                 continue
+
             table = self.resolve_table_object(child.func.value)
             if table and table not in tables:
                 tables.append(table)
 
         return tables
 
-    def walk_statements(self, statements, operations, phase, condition):
+    @staticmethod
+    def _is_table_handler_call(call, attr=None):
+        """True für Aufrufe der Form `backend.TableHandler.<attr>(...)`."""
+        is_handler = (
+            isinstance(call.func.value, ast.Attribute)
+            and call.func.value.attr == "TableHandler"
+            and isinstance(call.func.value.value, ast.Name)
+            and call.func.value.value.id == "backend"
+        )
+        if not is_handler:
+            return False
+        return attr is None or call.func.attr == attr
 
+    # -- Statements/Ausdrücke durchlaufen ------------------------------------
+
+    def walk_statements(self, statements, operations, phase, condition):
+        """
+        Läuft über eine Liste von Statements und sammelt DB-Operationen ein.
+        `phase` wechselt von "before_super" auf "after_super", sobald der
+        super().__register__(...)-Aufruf gefunden wird. `condition` trägt
+        den Text einer umschließenden if-Bedingung mit, falls vorhanden.
+        """
         for stmt in statements:
 
             if self.is_super_register(stmt):
@@ -265,7 +356,6 @@ class RegisterExtractor(ast.NodeVisitor):
                 self.walk_expression(value, operations, phase, condition)
 
     def walk_expression(self, node, operations, phase, condition):
-
         if node is None:
             return
 
@@ -281,21 +371,16 @@ class RegisterExtractor(ast.NodeVisitor):
             self.walk_expression(child, operations, phase, condition)
 
     def is_super_register(self, stmt):
-
+        """True für `super(...).__register__(...)` als eigenständiges Statement."""
         if not isinstance(stmt, ast.Expr):
             return False
 
         call = stmt.value
-
         if not isinstance(call, ast.Call):
             return False
 
         func = call.func
-
-        if not isinstance(func, ast.Attribute):
-            return False
-
-        if func.attr != "__register__":
+        if not isinstance(func, ast.Attribute) or func.attr != "__register__":
             return False
 
         if not isinstance(func.value, ast.Call):
@@ -306,99 +391,44 @@ class RegisterExtractor(ast.NodeVisitor):
 
         return func.value.func.id == "super"
 
+    # -- Einzelnen Aufruf in ein Operation-Dict übersetzen -------------------
+
     def extract_call(self, call):
-    
         if not isinstance(call.func, ast.Attribute):
             return None
-    
-        interesting = {
-            "column_rename",
-            "drop_column",
-            "add_column",
-            "drop_constraint",
-            "add_constraint",
-            "not_null_action",
-            "index_action",
-            "alter_size",
-            "execute",
-            "executemany",
-            "update",
-            "insert",
-            "delete",
-            "select",
-        }
-    
-        operation = call.func.attr
-    
-        is_table_handler = (
-            isinstance(call.func.value, ast.Attribute)
-            and call.func.value.attr == "TableHandler"
-            and isinstance(call.func.value.value, ast.Name)
-            and call.func.value.value.id == "backend"
-        )
 
-        if operation not in interesting and not is_table_handler:
+        operation = call.func.attr
+
+        is_table_handler = self._is_table_handler_call(call)
+
+        if operation not in INTERESTING_OPS and not is_table_handler:
             return None
 
         tables = self.find_tables(call)
-        
-        if (
-            isinstance(call.func, ast.Attribute)
-            and call.func.attr == "table_rename"
-            and isinstance(call.func.value, ast.Attribute)
-            and isinstance(call.func.value.value, ast.Name)
-            and call.func.value.value.id == "backend"
-            and isinstance(call.args, list)
-        ):
-            for arg in call.args[:2]:
-                if isinstance(arg, ast.Constant) and isinstance(arg.value, str):
-                    table = arg.value
-                elif isinstance(arg, ast.Name):
-                    table = self.table_vars.get(arg.id)
-                elif (
-                    isinstance(arg, ast.Attribute)
-                    and isinstance(arg.value, ast.Name)
-                    and arg.value.id == "cls"
-                    and arg.attr == "_table"
-                ):
-                    table = self.model_names.get(self.current_class)
-                    if table:
-                        table = table.replace(".", "_")
-                else:
-                    table = None
+        tables += self._extra_tables_from_table_rename(call, tables)
 
-                if table and table not in tables:
-                    tables.append(table)    
-                    
         # Wer wird aufgerufen?
         if isinstance(call.func.value, ast.Name):
             obj = call.func.value.id
         else:
             obj = ast.unparse(call.func.value)
-    
+
         args = []
-    
         for arg in call.args:
             try:
                 args.append(ast.unparse(arg))
             except Exception:
                 args.append("<unknown>")
-    
+
         kwargs = {}
-    
         for kw in call.keywords:
             try:
                 kwargs[kw.arg] = ast.unparse(kw.value)
             except Exception:
                 kwargs[kw.arg] = "<unknown>"
-        code = ast.get_source_segment(self.source, call)
 
-        for name, value in self.alias_vars.items():
-            code = re.sub(
-                rf"\b{re.escape(name)}\b",
-                f"({value})",
-                code,
-            )
+        code = self._render_code(call)
+
         return {
             "object": obj,
             "operation": operation,
@@ -409,8 +439,69 @@ class RegisterExtractor(ast.NodeVisitor):
             "code": code,
         }
 
-def analyse_file(module, modulepath, filename):
+    def _extra_tables_from_table_rename(self, call, existing_tables):
+        """
+        Sonderfall `backend.TableHandler.table_rename(old, new)`: die ersten
+        beiden Argumente können selbst Tabellen(-namen) sein und werden hier
+        zusätzlich zu den bereits gefundenen Tabellen ergänzt.
+        """
+        is_table_rename = (
+            call.func.attr == "table_rename"
+            and isinstance(call.func.value, ast.Attribute)
+            and isinstance(call.func.value.value, ast.Name)
+            and call.func.value.value.id == "backend"
+            and isinstance(call.args, list)
+        )
+        if not is_table_rename:
+            return []
 
+        extra = []
+        for arg in call.args[:2]:
+            if isinstance(arg, ast.Constant) and isinstance(arg.value, str):
+                table = arg.value
+            elif isinstance(arg, ast.Name):
+                table = self.table_vars.get(arg.id)
+            elif (
+                isinstance(arg, ast.Attribute)
+                and isinstance(arg.value, ast.Name)
+                and arg.value.id == "cls"
+                and arg.attr == "_table"
+            ):
+                table = self.model_names.get(self.current_class)
+                if table:
+                    table = table.replace(".", "_")
+            else:
+                table = None
+
+            if table and table not in existing_tables and table not in extra:
+                extra.append(table)
+
+        return extra
+
+    def _render_code(self, call):
+        """
+        Quelltext des Aufrufs, wobei zuvor gemerkte Alias-Variablen
+        (siehe alias_vars) durch ihren ursprünglichen Ausdruck ersetzt
+        werden, damit der Code auch ohne Kontext lesbar ist.
+        """
+        code = ast.get_source_segment(self.source, call)
+
+        for name, value in self.alias_vars.items():
+            code = re.sub(
+                rf"\b{re.escape(name)}\b",
+                f"({value})",
+                code,
+            )
+
+        return code
+
+
+# --------------------------------------------------------------------------
+# Datei-/Repo-Ebene
+# --------------------------------------------------------------------------
+
+def analyse_file(module, modulepath, filename):
+    """Parst eine einzelne Datei und liefert alle __register__-Ergebnisse mit Operationen."""
     path = modulepath / filename
     try:
         source = path.read_text(encoding="utf-8")
@@ -422,11 +513,11 @@ def analyse_file(module, modulepath, filename):
     visitor = RegisterExtractor(source, module, filename)
     visitor.visit(tree)
 
-    results = [r for r in visitor.results if r["operations"]]
-    
-    return results
+    return [r for r in visitor.results if r["operations"]]
+
 
 def detect_version(repo: Path) -> str:
+    """Liest die aktuelle Version aus trytond/CHANGELOG."""
     changelog = repo / "trytond" / "CHANGELOG"
 
     if not changelog.exists():
@@ -435,49 +526,78 @@ def detect_version(repo: Path) -> str:
     with changelog.open("r", encoding="utf-8") as f:
         for line in f:
             if line.startswith("Version "):
-                return line.split()[1].rsplit('.', 1)[0]
+                return line.split()[1].rsplit(".", 1)[0]
 
     return "unknown"
 
-def find_module(repo: Path, module: str) -> Path | None:
 
+def find_module(repo: Path, module: str) -> Path | None:
+    """Sucht ein Modul entweder unter modules/ oder trytond/trytond/."""
     candidates = [
         repo / "modules" / module,
         repo / "trytond" / "trytond" / module,
     ]
 
-    for c in candidates:
-        if c.exists():
-            return c
+    for candidate in candidates:
+        if candidate.exists():
+            return candidate
 
     return None
 
-def main():
 
+def analyse_module(repo: Path, module: str) -> list | None:
+    """Analysiert alle .py-Dateien eines Moduls. None, falls Modul nicht gefunden."""
+    module_path = find_module(repo, module)
+    if not module_path:
+        return None
+
+    results = []
+    for py in sorted(module_path.rglob("*.py")):
+        filename = str(py.relative_to(module_path))
+        results.extend(analyse_file(module, module_path, filename))
+
+    return results
+
+
+def write_results(output: Path, version: str, module: str, results: list) -> Path:
+    """Schreibt die Ergebnisse eines Moduls als JSON und gibt den Pfad zurück."""
+    outdir = output / version
+    outdir.mkdir(parents=True, exist_ok=True)
+
+    outfile = outdir / f"{module}.json"
+    with outfile.open("w", encoding="utf-8") as f:
+        json.dump(
+            {
+                "version": version,
+                "module": module,
+                "files": results,
+            },
+            f,
+            indent=2,
+        )
+
+    return outfile
+
+
+# --------------------------------------------------------------------------
+# CLI
+# --------------------------------------------------------------------------
+
+def parse_args():
     parser = argparse.ArgumentParser()
 
-    parser.add_argument(
-        "--repo",
-        help="Path to Tryton repository",
-    )
+    parser.add_argument("--repo", help="Path to Tryton repository")
+    parser.add_argument("--modules", nargs="+", help="Module names")
+    parser.add_argument("--output", help="Output directory")
 
-    parser.add_argument(
-        "--modules",
-        nargs="+",
-        help="Module names",
-    )
+    return parser.parse_args()
 
-    parser.add_argument(
-        "--output",
-        help="Output directory",
-    )
 
-    args = parser.parse_args()
+def main():
+    args = parse_args()
 
     repo = Path(args.repo or DEFAULT_REPO)
-
     modules = args.modules or DEFAULT_MODULES
-
     output = Path(args.output or DEFAULT_OUTPUT)
 
     version = detect_version(repo)
@@ -488,35 +608,13 @@ def main():
     print()
 
     for module in modules:
+        results = analyse_module(repo, module)
 
-        module_path = find_module(repo, module)
-
-        if not module_path:
+        if results is None:
             print(f"Module not found: {module}")
             continue
 
-        results = []
-
-        for py in sorted(module_path.rglob("*.py")):
-            filename = str(py.relative_to(module_path))
-            results.extend(analyse_file(module, module_path, filename))
-
-        outdir = output / version
-        outdir.mkdir(parents=True, exist_ok=True)
-
-        outfile = outdir / f"{module}.json"
-
-        with outfile.open("w", encoding="utf-8") as f:
-            json.dump(
-                {
-                    "version": version,
-                    "module": module,
-                    "files": results,
-                },
-                f,
-                indent=2,
-            )
-
+        outfile = write_results(output, version, module, results)
         print(f"{module:25} -> {outfile}")