From 3f18b0faae381f901ee2cd2eb99defa51bf82cc8 Mon Sep 17 00:00:00 2001
From: alex <a.jurcenko@inproduct.de>
Date: Tue, 11 Aug 2026 23:11:24 +0200
Subject: [PATCH] worked on gui pyside6

---
 .gitignore                      |    2 +
 abacus_ide.py                   |  761 +++++++++++++++++++++
 abacus_ide_checked.py           |  774 ++++++++++++++++++++++
 abacus_ide_checked_final.py     | 1091 +++++++++++++++++++++++++++++++
 abacus_ide_fixed.py             |  761 +++++++++++++++++++++
 abacus_ide_fixed_v2.py          |  764 ++++++++++++++++++++++
 abacus_ide_json_autocomplete.py | 1057 ++++++++++++++++++++++++++++++
 abacus_pyside6.py               |  354 ++++++++++
 abacus_pyside6_v2.py            |  360 ++++++++++
 dieselfloater_edeka.json        |   30 +
 test.json                       |   46 ++
 11 files changed, 6000 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 abacus_ide.py
 create mode 100644 abacus_ide_checked.py
 create mode 100644 abacus_ide_checked_final.py
 create mode 100644 abacus_ide_fixed.py
 create mode 100644 abacus_ide_fixed_v2.py
 create mode 100644 abacus_ide_json_autocomplete.py
 create mode 100644 abacus_pyside6.py
 create mode 100644 abacus_pyside6_v2.py
 create mode 100644 dieselfloater_edeka.json
 create mode 100644 test.json

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..eb53ea0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+/.venv
+/.idea
\ No newline at end of file
diff --git a/abacus_ide.py b/abacus_ide.py
new file mode 100644
index 0000000..91ef67b
--- /dev/null
+++ b/abacus_ide.py
@@ -0,0 +1,761 @@
+import math
+import sys
+
+from PySide6.QtCore import Qt, QRect, QSize
+from PySide6.QtGui import (
+    QColor,
+    QFont,
+    QPainter,
+    QSyntaxHighlighter,
+    QTextCharFormat,
+)
+from PySide6.QtWidgets import (
+    QApplication,
+    QDockWidget,
+    QFrame,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListWidget,
+    QMainWindow,
+    QPlainTextEdit,
+    QPushButton,
+    QSplitter,
+    QStatusBar,
+    QTabWidget,
+    QTableWidget,
+    QTableWidgetItem,
+    QToolBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+from abacus_core import AbacusCore
+
+
+STYLE = """
+QMainWindow, QWidget {
+    background: #0d1117;
+    color: #e6edf3;
+    font-family: "Segoe UI";
+    font-size: 13px;
+}
+
+QToolBar {
+    background: #111820;
+    border: 0;
+    border-bottom: 1px solid #202a36;
+    spacing: 5px;
+    padding: 6px 8px;
+}
+
+QToolButton {
+    color: #c9d1d9;
+    background: transparent;
+    border-radius: 7px;
+    padding: 7px 10px;
+}
+
+QToolButton:hover {
+    background: #1b2531;
+    color: #ffffff;
+}
+
+QTabWidget::pane {
+    border: 1px solid #202a36;
+    background: #0d1117;
+}
+
+QTabBar::tab {
+    background: #111820;
+    color: #7d8b99;
+    border: 1px solid #202a36;
+    border-bottom: none;
+    padding: 9px 16px;
+    margin-right: 2px;
+}
+
+QTabBar::tab:selected {
+    background: #17212c;
+    color: #f0f6fc;
+}
+
+QDockWidget {
+    color: #aeb9c6;
+    titlebar-close-icon: none;
+    titlebar-normal-icon: none;
+}
+
+QDockWidget::title {
+    background: #111820;
+    border-bottom: 1px solid #202a36;
+    padding: 9px 11px;
+    font-weight: 700;
+}
+
+QFrame#editorCard, QFrame#bottomCard {
+    background: #111820;
+    border: 1px solid #202a36;
+    border-radius: 10px;
+}
+
+QPlainTextEdit {
+    background: #0b0f14;
+    color: #d6deea;
+    border: 1px solid #202a36;
+    border-radius: 9px;
+    selection-background-color: #244a7d;
+    padding: 8px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+    font-size: 14px;
+}
+
+QLineEdit#singleLine {
+    background: #0b0f14;
+    color: #f0f6fc;
+    border: 1px solid #303b48;
+    border-radius: 9px;
+    padding: 9px 11px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+}
+
+QLineEdit#singleLine:focus {
+    border: 1px solid #3b82f6;
+}
+
+QPushButton {
+    background: #2563eb;
+    color: white;
+    border: none;
+    border-radius: 8px;
+    padding: 8px 13px;
+    font-weight: 700;
+}
+
+QPushButton:hover {
+    background: #3475ef;
+}
+
+QPushButton#operator {
+    background: #1b2531;
+    color: #cbd5e1;
+    border: 1px solid #293543;
+    min-width: 34px;
+}
+
+QPushButton#operator:hover {
+    background: #253344;
+    color: #ffffff;
+}
+
+QPushButton#secondary {
+    background: #1b2531;
+    color: #b9c4d0;
+    border: 1px solid #293543;
+}
+
+QListWidget, QTableWidget {
+    background: #0d131a;
+    color: #cbd5e1;
+    border: 1px solid #202a36;
+    border-radius: 8px;
+    outline: none;
+}
+
+QListWidget::item {
+    padding: 7px 8px;
+    border-radius: 6px;
+}
+
+QListWidget::item:hover {
+    background: #17212c;
+}
+
+QListWidget::item:selected {
+    background: #1c3153;
+    color: #ffffff;
+}
+
+QHeaderView::section {
+    background: #161f29;
+    color: #9aa8b7;
+    border: none;
+    border-right: 1px solid #202a36;
+    border-bottom: 1px solid #202a36;
+    padding: 7px;
+}
+
+QTableWidget::item {
+    padding: 6px;
+    border-bottom: 1px solid #18212b;
+}
+
+QStatusBar {
+    background: #0b0f14;
+    color: #7d8b99;
+    border-top: 1px solid #202a36;
+}
+
+QScrollBar:vertical {
+    background: #0d131a;
+    width: 9px;
+}
+
+QScrollBar::handle:vertical {
+    background: #303c4a;
+    border-radius: 4px;
+    min-height: 25px;
+}
+
+QScrollBar::add-line:vertical,
+QScrollBar::sub-line:vertical {
+    height: 0;
+}
+"""
+
+
+class AbacusHighlighter(QSyntaxHighlighter):
+    def __init__(self, document):
+        super().__init__(document)
+
+        self.number = QTextCharFormat()
+        self.number.setForeground(QColor("#79c0ff"))
+
+        self.operator = QTextCharFormat()
+        self.operator.setForeground(QColor("#ff7b72"))
+
+        self.comment = QTextCharFormat()
+        self.comment.setForeground(QColor("#6e7681"))
+        self.comment.setFontItalic(True)
+
+        self.assignment = QTextCharFormat()
+        self.assignment.setForeground(QColor("#d2a8ff"))
+
+        self.keyword = QTextCharFormat()
+        self.keyword.setForeground(QColor("#ffa657"))
+
+    def highlightBlock(self, text):
+        # Comments
+        comment_pos = text.find("#")
+        if comment_pos >= 0:
+            self.setFormat(comment_pos, len(text) - comment_pos, self.comment)
+            code = text[:comment_pos]
+        else:
+            code = text
+
+        # Numbers
+        i = 0
+        while i < len(code):
+            if code[i].isdigit() or (
+                code[i] == "." and i + 1 < len(code) and code[i + 1].isdigit()
+            ):
+                start = i
+                i += 1
+                while i < len(code) and (code[i].isdigit() or code[i] == "."):
+                    i += 1
+                self.setFormat(start, i - start, self.number)
+            else:
+                i += 1
+
+        for char in "+-*/=():[];":
+            start = 0
+            while True:
+                pos = code.find(char, start)
+                if pos < 0:
+                    break
+                self.setFormat(pos, 1, self.operator)
+                start = pos + 1
+
+        # Function definitions: name before ':'
+        colon = code.find(":")
+        if colon > 0:
+            name = code[:colon].strip()
+            if name:
+                pos = code.find(name)
+                self.setFormat(pos, len(name), self.keyword)
+
+
+class LineNumberArea(QWidget):
+    def __init__(self, editor):
+        super().__init__(editor)
+        self.editor = editor
+
+    def sizeHint(self):
+        return QSize(self.editor.line_number_width(), 0)
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.fillRect(event.rect(), QColor("#0f151c"))
+
+        block = self.editor.firstVisibleBlock()
+        block_number = block.blockNumber()
+        top = int(
+            self.editor.blockBoundingGeometry(block).translated(
+                self.editor.contentOffset()
+            ).top()
+        )
+        bottom = top + int(self.editor.blockBoundingRect(block).height())
+
+        while block.isValid() and top <= event.rect().bottom():
+            if block.isVisible() and bottom >= event.rect().top():
+                painter.setPen(QColor("#596878"))
+                painter.drawText(
+                    0,
+                    top,
+                    self.width() - 7,
+                    self.editor.fontMetrics().height(),
+                    Qt.AlignRight,
+                    str(block_number + 1),
+                )
+
+            block = block.next()
+            top = bottom
+            bottom = top + int(self.editor.blockBoundingRect(block).height())
+            block_number += 1
+
+
+class CodeEditor(QPlainTextEdit):
+    def __init__(self):
+        super().__init__()
+
+        self.line_numbers = LineNumberArea(self)
+        self.blockCountChanged.connect(self.update_line_number_width)
+        self.updateRequest.connect(self.update_line_number_area)
+        self.cursorPositionChanged.connect(self.highlight_current_line)
+
+        self.update_line_number_width(0)
+        self.highlight_current_line()
+
+        font = QFont("JetBrains Mono", 11)
+        font.setStyleHint(QFont.Monospace)
+        self.setFont(font)
+        self.setTabStopDistance(
+            self.fontMetrics().horizontalAdvance(" ") * 4
+        )
+
+    def line_number_width(self):
+        digits = len(str(max(1, self.blockCount())))
+        return 12 + self.fontMetrics().horizontalAdvance("9") * digits
+
+    def update_line_number_width(self, _):
+        self.setViewportMargins(self.line_number_width(), 0, 0, 0)
+
+    def update_line_number_area(self, rect, dy):
+        if dy:
+            self.line_numbers.scroll(0, dy)
+        else:
+            self.line_numbers.update(0, rect.y(), self.line_numbers.width(), rect.height())
+
+        if rect.contains(self.viewport().rect()):
+            self.update_line_number_width(0)
+
+    def resizeEvent(self, event):
+        super().resizeEvent(event)
+        rect = self.contentsRect()
+        rect.setWidth(self.line_number_width())
+        self.line_numbers.setGeometry(rect)
+
+    def highlight_current_line(self):
+        extra = []
+        if not self.isReadOnly():
+            selection = QTextCharFormat()
+            selection.setBackground(QColor("#111a24"))
+            selection.setProperty(QTextCharFormat.FullWidthSelection, True)
+            extra.append((self.textCursor(), selection))
+        self.setExtraSelections(extra)
+
+
+class ResultGraph(QWidget):
+    """Small dependency-free graph of numeric results."""
+
+    def __init__(self):
+        super().__init__()
+        self.values = []
+
+    def set_values(self, values):
+        self.values = values[-50:]
+        self.update()
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.Antialiasing)
+        painter.fillRect(self.rect(), QColor("#0b0f14"))
+
+        r = self.rect().adjusted(45, 20, -20, -35)
+        painter.setPen(QColor("#273442"))
+        painter.drawRect(r)
+
+        if not self.values:
+            painter.setPen(QColor("#647383"))
+            painter.drawText(r, Qt.AlignCenter, "No numeric results yet")
+            return
+
+        numeric = [v for v in self.values if math.isfinite(v)]
+        if not numeric:
+            return
+
+        lo = min(numeric)
+        hi = max(numeric)
+        if abs(hi - lo) < 1e-12:
+            lo -= 1
+            hi += 1
+
+        painter.setPen(QColor("#344454"))
+        for frac in (0.0, 0.5, 1.0):
+            y = int(r.bottom() - frac * r.height())
+            painter.drawLine(r.left(), y, r.right(), y)
+
+        painter.setPen(QColor("#5f6f80"))
+        painter.drawText(5, r.top() + 5, 35, 20, Qt.AlignRight, f"{hi:g}")
+        painter.drawText(5, r.bottom() - 15, 35, 20, Qt.AlignRight, f"{lo:g}")
+
+        if len(numeric) == 1:
+            x = r.center().x()
+            y = r.bottom() - (numeric[0] - lo) / (hi - lo) * r.height()
+            painter.setBrush(QColor("#58a6ff"))
+            painter.drawEllipse(int(x - 4), int(y - 4), 8, 8)
+            return
+
+        points = []
+        count = len(numeric)
+        for i, value in enumerate(numeric):
+            x = r.left() + i * r.width() / max(1, count - 1)
+            y = r.bottom() - (value - lo) / (hi - lo) * r.height()
+            points.append((x, y))
+
+        painter.setPen(QColor("#58a6ff"))
+        for a, b in zip(points, points[1:]):
+            painter.drawLine(int(a[0]), int(a[1]), int(b[0]), int(b[1]))
+
+        painter.setBrush(QColor("#58a6ff"))
+        for x, y in points:
+            painter.drawEllipse(int(x - 3), int(y - 3), 6, 6)
+
+
+class AbacusIDE(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.core = AbacusCore()
+        self.step = 0
+        self.results = []
+
+        self.setWindowTitle("Abacus IDE")
+        self.resize(1400, 850)
+        self.setMinimumSize(1050, 650)
+
+        self._build_toolbar()
+        self._build_main()
+        self._build_docks()
+        self._build_statusbar()
+
+        self._refresh_sidebars()
+        self.editor.setFocus()
+
+    def _build_toolbar(self):
+        toolbar = QToolBar()
+        toolbar.setMovable(False)
+        toolbar.setToolButtonStyle(Qt.ToolButtonTextOnly)
+        self.addToolBar(toolbar)
+
+        run = toolbar.addAction("▶  Run")
+        run.triggered.connect(self.run_document)
+
+        run_line = toolbar.addAction("Run line")
+        run_line.triggered.connect(self.run_current_line)
+
+        toolbar.addSeparator()
+
+        for symbol in ("+", "-", "*", "/", "(", ")", "[", "]", "="):
+            button = QPushButton(symbol)
+            button.setObjectName("operator")
+            button.clicked.connect(
+                lambda checked=False, s=symbol: self.insert_operator(s)
+            )
+            toolbar.addWidget(button)
+
+        toolbar.addSeparator()
+
+        clear = toolbar.addAction("Clear")
+        clear.triggered.connect(self.editor.clear)
+
+        toolbar.addSeparator()
+
+        reset = toolbar.addAction("Reset")
+        reset.triggered.connect(self.reset_abacus)
+
+    def _build_main(self):
+        self.tabs = QTabWidget()
+        self.setCentralWidget(self.tabs)
+
+        # Workspace tab
+        workspace = QWidget()
+        workspace_layout = QVBoxLayout(workspace)
+        workspace_layout.setContentsMargins(10, 10, 10, 10)
+        workspace_layout.setSpacing(8)
+
+        editor_header = QHBoxLayout()
+        label = QLabel("Expression editor")
+        label.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+
+        hint = QLabel(
+            "One command per line  •  # comments  •  Enter = run line"
+        )
+        hint.setStyleSheet("color: #657585;")
+
+        editor_header.addWidget(label)
+        editor_header.addStretch()
+        editor_header.addWidget(hint)
+        workspace_layout.addLayout(editor_header)
+
+        self.editor = CodeEditor()
+        AbacusHighlighter(self.editor.document())
+        self.editor.setPlainText(
+            "# Example\n"
+            "alpha = 10\n"
+            "beta = 2\n"
+            "alpha + beta * 3\n"
+        )
+        workspace_layout.addWidget(self.editor, 1)
+
+        bottom = QFrame()
+        bottom.setObjectName("bottomCard")
+        bottom_layout = QHBoxLayout(bottom)
+        bottom_layout.setContentsMargins(10, 8, 10, 8)
+
+        bottom_layout.addWidget(QLabel("Quick input:"))
+
+        self.single_line = QLineEdit()
+        self.single_line.setObjectName("singleLine")
+        self.single_line.setPlaceholderText("Enter expression...")
+        self.single_line.returnPressed.connect(self.run_single_line)
+        bottom_layout.addWidget(self.single_line, 1)
+
+        execute = QPushButton("Execute")
+        execute.clicked.connect(self.run_single_line)
+        bottom_layout.addWidget(execute)
+
+        workspace_layout.addWidget(bottom)
+
+        self.tabs.addTab(workspace, "Workspace")
+
+        # Results tab
+        results_page = QWidget()
+        results_layout = QVBoxLayout(results_page)
+        results_layout.setContentsMargins(10, 10, 10, 10)
+
+        self.results_table = QTableWidget(0, 4)
+        self.results_table.setHorizontalHeaderLabels(
+            ["Step", "Expression", "Result", "Comment"]
+        )
+        self.results_table.horizontalHeader().setStretchLastSection(True)
+        self.results_table.setAlternatingRowColors(False)
+        results_layout.addWidget(self.results_table)
+
+        self.tabs.addTab(results_page, "Results")
+
+        # Graph tab
+        graph_page = QWidget()
+        graph_layout = QVBoxLayout(graph_page)
+        graph_layout.setContentsMargins(10, 10, 10, 10)
+
+        graph_title = QLabel("Numeric result history")
+        graph_title.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+        graph_layout.addWidget(graph_title)
+
+        self.graph = ResultGraph()
+        graph_layout.addWidget(self.graph, 1)
+
+        graph_info = QLabel(
+            "The graph uses numeric results from executed expressions."
+        )
+        graph_info.setStyleSheet("color: #657585;")
+        graph_layout.addWidget(graph_info)
+
+        self.tabs.addTab(graph_page, "Graph")
+
+    def _build_docks(self):
+        self.variables_dock = self._make_dock(
+            "Variables", self._make_list_widget()
+        )
+        self.functions_dock = self._make_dock(
+            "Functions", self._make_list_widget()
+        )
+        self.history_dock = self._make_dock(
+            "History", self._make_list_widget()
+        )
+
+        self.variables_list = self.variables_dock.widget()
+        self.functions_list = self.functions_dock.widget()
+        self.history_list = self.history_dock.widget()
+
+        self.addDockWidget(Qt.RightDockWidgetArea, self.variables_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.functions_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.history_dock)
+
+        self.tabifyDockWidget(self.variables_dock, self.functions_dock)
+        self.tabifyDockWidget(self.functions_dock, self.history_dock)
+        self.variables_dock.raise_()
+
+    def _make_list_widget(self):
+        return QListWidget()
+
+    def _make_dock(self, title, widget):
+        dock = QDockWidget(title, self)
+        dock.setAllowedAreas(
+            Qt.LeftDockWidgetArea | Qt.RightDockWidgetArea
+        )
+        dock.setFeatures(
+            QDockWidget.DockWidgetMovable
+            | QDockWidget.DockWidgetFloatable
+        )
+        dock.setWidget(widget)
+        return dock
+
+    def _build_statusbar(self):
+        self.status = QStatusBar()
+        self.setStatusBar(self.status)
+        self.status.showMessage("Ready")
+
+    def insert_operator(self, symbol):
+        self.editor.insertPlainText(symbol)
+        self.editor.setFocus()
+
+    def run_single_line(self):
+        text = self.single_line.text().strip()
+        if not text:
+            return
+
+        self._execute(text)
+        self.single_line.clear()
+
+    def run_current_line(self):
+        cursor = self.editor.textCursor()
+        cursor.select(cursor.LineUnderCursor)
+        line = cursor.selectedText().strip()
+
+        if line:
+            self._execute(line)
+
+    def run_document(self):
+        lines = self.editor.toPlainText().splitlines()
+
+        executed = 0
+        for line in lines:
+            line = line.strip()
+            if not line or line.startswith("#"):
+                continue
+
+            self._execute(line)
+            executed += 1
+
+        self.status.showMessage(f"Executed {executed} command(s)")
+
+    def _execute(self, text):
+        self.step += 1
+
+        try:
+            result = self.core.parse_input(text)
+        except Exception as exc:
+            self.step -= 1
+            self.status.showMessage(f"Error: {exc}")
+            self.history_list.addItem(f"ERROR  {text}  →  {exc}")
+            return
+
+        # Critical: assignments/functions return None, but their
+        # dictionaries are already changed. Refresh immediately.
+        self._refresh_sidebars()
+
+        if not result:
+            self.status.showMessage(f"Updated: {text}")
+            return
+
+        original, _, value, comment = result
+        value_text = str(value)
+        comment_text = comment or ""
+
+        self.results.append(
+            {
+                "step": self.step,
+                "expression": original,
+                "result": value_text,
+                "comment": comment_text,
+            }
+        )
+
+        self.history_list.addItem(
+            f"{self.step}.  {original}  =  {value_text}"
+        )
+        self.history_list.scrollToBottom()
+
+        self._add_result_row(
+            self.step, original, value_text, comment_text
+        )
+
+        try:
+            numeric = float(value)
+        except (TypeError, ValueError):
+            numeric = None
+
+        if numeric is not None and math.isfinite(numeric):
+            self.graph.values.append(numeric)
+            self.graph.set_values(self.graph.values)
+
+        self.status.showMessage(f"Result: {value_text}")
+
+    def _add_result_row(self, step, expression, result, comment):
+        row = self.results_table.rowCount()
+        self.results_table.insertRow(row)
+
+        values = [str(step), expression, result, comment]
+
+        for col, value in enumerate(values):
+            self.results_table.setItem(
+                row, col, QTableWidgetItem(value)
+            )
+
+        self.results_table.resizeColumnsToContents()
+        self.results_table.scrollToBottom()
+
+    def _refresh_sidebars(self):
+        self.variables_list.clear()
+
+        for key, value in self.core.get_vars().items():
+            self.variables_list.addItem(f"{key}    =    {value}")
+
+        self.functions_list.clear()
+
+        for key, value in self.core.get_funcs().items():
+            self.functions_list.addItem(f"{key}    =    {value}")
+
+    def reset_abacus(self):
+        self.core = AbacusCore()
+        self.step = 0
+        self.results.clear()
+
+        self.variables_list.clear()
+        self.functions_list.clear()
+        self.history_list.clear()
+        self.results_table.setRowCount(0)
+
+        self.graph.set_values([])
+        self.status.showMessage("Abacus state reset")
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+    app.setStyleSheet(STYLE)
+
+    window = AbacusIDE()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/abacus_ide_checked.py b/abacus_ide_checked.py
new file mode 100644
index 0000000..08be22e
--- /dev/null
+++ b/abacus_ide_checked.py
@@ -0,0 +1,774 @@
+import math
+import sys
+
+from PySide6.QtCore import Qt, QSize
+from PySide6.QtGui import (
+    QColor,
+    QFont,
+    QPainter,
+    QSyntaxHighlighter,
+    QTextCharFormat,
+)
+from PySide6.QtWidgets import (
+    QApplication,
+    QDockWidget,
+    QFrame,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListWidget,
+    QMainWindow,
+    QPlainTextEdit,
+    QTextEdit,
+    QPushButton,
+    QStatusBar,
+    QTabWidget,
+    QTableWidget,
+    QTableWidgetItem,
+    QToolBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+from abacus_core import AbacusCore
+
+
+STYLE = """
+QMainWindow, QWidget {
+    background: #0d1117;
+    color: #e6edf3;
+    font-family: "Segoe UI";
+    font-size: 13px;
+}
+
+QToolBar {
+    background: #111820;
+    border: 0;
+    border-bottom: 1px solid #202a36;
+    spacing: 5px;
+    padding: 6px 8px;
+}
+
+QToolButton {
+    color: #c9d1d9;
+    background: transparent;
+    border-radius: 7px;
+    padding: 7px 10px;
+}
+
+QToolButton:hover {
+    background: #1b2531;
+    color: #ffffff;
+}
+
+QTabWidget::pane {
+    border: 1px solid #202a36;
+    background: #0d1117;
+}
+
+QTabBar::tab {
+    background: #111820;
+    color: #7d8b99;
+    border: 1px solid #202a36;
+    border-bottom: none;
+    padding: 9px 16px;
+    margin-right: 2px;
+}
+
+QTabBar::tab:selected {
+    background: #17212c;
+    color: #f0f6fc;
+}
+
+QDockWidget {
+    color: #aeb9c6;
+    titlebar-close-icon: none;
+    titlebar-normal-icon: none;
+}
+
+QDockWidget::title {
+    background: #111820;
+    border-bottom: 1px solid #202a36;
+    padding: 9px 11px;
+    font-weight: 700;
+}
+
+QFrame#editorCard, QFrame#bottomCard {
+    background: #111820;
+    border: 1px solid #202a36;
+    border-radius: 10px;
+}
+
+QPlainTextEdit {
+    background: #0b0f14;
+    color: #d6deea;
+    border: 1px solid #202a36;
+    border-radius: 9px;
+    selection-background-color: #244a7d;
+    padding: 8px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+    font-size: 14px;
+}
+
+QLineEdit#singleLine {
+    background: #0b0f14;
+    color: #f0f6fc;
+    border: 1px solid #303b48;
+    border-radius: 9px;
+    padding: 9px 11px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+}
+
+QLineEdit#singleLine:focus {
+    border: 1px solid #3b82f6;
+}
+
+QPushButton {
+    background: #2563eb;
+    color: white;
+    border: none;
+    border-radius: 8px;
+    padding: 8px 13px;
+    font-weight: 700;
+}
+
+QPushButton:hover {
+    background: #3475ef;
+}
+
+QPushButton#operator {
+    background: #1b2531;
+    color: #cbd5e1;
+    border: 1px solid #293543;
+    min-width: 34px;
+}
+
+QPushButton#operator:hover {
+    background: #253344;
+    color: #ffffff;
+}
+
+QPushButton#secondary {
+    background: #1b2531;
+    color: #b9c4d0;
+    border: 1px solid #293543;
+}
+
+QListWidget, QTableWidget {
+    background: #0d131a;
+    color: #cbd5e1;
+    border: 1px solid #202a36;
+    border-radius: 8px;
+    outline: none;
+}
+
+QListWidget::item {
+    padding: 7px 8px;
+    border-radius: 6px;
+}
+
+QListWidget::item:hover {
+    background: #17212c;
+}
+
+QListWidget::item:selected {
+    background: #1c3153;
+    color: #ffffff;
+}
+
+QHeaderView::section {
+    background: #161f29;
+    color: #9aa8b7;
+    border: none;
+    border-right: 1px solid #202a36;
+    border-bottom: 1px solid #202a36;
+    padding: 7px;
+}
+
+QTableWidget::item {
+    padding: 6px;
+    border-bottom: 1px solid #18212b;
+}
+
+QStatusBar {
+    background: #0b0f14;
+    color: #7d8b99;
+    border-top: 1px solid #202a36;
+}
+
+QScrollBar:vertical {
+    background: #0d131a;
+    width: 9px;
+}
+
+QScrollBar::handle:vertical {
+    background: #303c4a;
+    border-radius: 4px;
+    min-height: 25px;
+}
+
+QScrollBar::add-line:vertical,
+QScrollBar::sub-line:vertical {
+    height: 0;
+}
+"""
+
+
+class AbacusHighlighter(QSyntaxHighlighter):
+    def __init__(self, document):
+        super().__init__(document)
+
+        self.number = QTextCharFormat()
+        self.number.setForeground(QColor("#79c0ff"))
+
+        self.operator = QTextCharFormat()
+        self.operator.setForeground(QColor("#ff7b72"))
+
+        self.comment = QTextCharFormat()
+        self.comment.setForeground(QColor("#6e7681"))
+        self.comment.setFontItalic(True)
+
+        self.assignment = QTextCharFormat()
+        self.assignment.setForeground(QColor("#d2a8ff"))
+
+        self.keyword = QTextCharFormat()
+        self.keyword.setForeground(QColor("#ffa657"))
+
+    def highlightBlock(self, text):
+        # Comments
+        comment_pos = text.find("#")
+        if comment_pos >= 0:
+            self.setFormat(comment_pos, len(text) - comment_pos, self.comment)
+            code = text[:comment_pos]
+        else:
+            code = text
+
+        # Numbers
+        i = 0
+        while i < len(code):
+            if code[i].isdigit() or (
+                code[i] == "." and i + 1 < len(code) and code[i + 1].isdigit()
+            ):
+                start = i
+                i += 1
+                while i < len(code) and (code[i].isdigit() or code[i] == "."):
+                    i += 1
+                self.setFormat(start, i - start, self.number)
+            else:
+                i += 1
+
+        for char in "+-*/=():[];":
+            start = 0
+            while True:
+                pos = code.find(char, start)
+                if pos < 0:
+                    break
+                self.setFormat(pos, 1, self.operator)
+                start = pos + 1
+
+        # Function definitions: name before ':'
+        colon = code.find(":")
+        if colon > 0:
+            name = code[:colon].strip()
+            if name:
+                pos = code.find(name)
+                self.setFormat(pos, len(name), self.keyword)
+
+
+class LineNumberArea(QWidget):
+    def __init__(self, editor):
+        super().__init__(editor)
+        self.editor = editor
+
+    def sizeHint(self):
+        return QSize(self.editor.line_number_width(), 0)
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.fillRect(event.rect(), QColor("#0f151c"))
+
+        block = self.editor.firstVisibleBlock()
+        block_number = block.blockNumber()
+        top = int(
+            self.editor.blockBoundingGeometry(block).translated(
+                self.editor.contentOffset()
+            ).top()
+        )
+        bottom = top + int(self.editor.blockBoundingRect(block).height())
+
+        while block.isValid() and top <= event.rect().bottom():
+            if block.isVisible() and bottom >= event.rect().top():
+                painter.setPen(QColor("#596878"))
+                painter.drawText(
+                    0,
+                    top,
+                    self.width() - 7,
+                    self.editor.fontMetrics().height(),
+                    Qt.AlignRight,
+                    str(block_number + 1),
+                )
+
+            block = block.next()
+            top = bottom
+            bottom = top + int(self.editor.blockBoundingRect(block).height())
+            block_number += 1
+
+
+class CodeEditor(QPlainTextEdit):
+    def __init__(self):
+        super().__init__()
+
+        self.line_numbers = LineNumberArea(self)
+        self.blockCountChanged.connect(self.update_line_number_width)
+        self.updateRequest.connect(self.update_line_number_area)
+        self.cursorPositionChanged.connect(self.highlight_current_line)
+
+        self.update_line_number_width(0)
+        self.highlight_current_line()
+
+        font = QFont("JetBrains Mono", 11)
+        font.setStyleHint(QFont.Monospace)
+        self.setFont(font)
+        self.setTabStopDistance(
+            self.fontMetrics().horizontalAdvance(" ") * 4
+        )
+
+    def line_number_width(self):
+        digits = len(str(max(1, self.blockCount())))
+        return 12 + self.fontMetrics().horizontalAdvance("9") * digits
+
+    def update_line_number_width(self, _):
+        self.setViewportMargins(self.line_number_width(), 0, 0, 0)
+
+    def update_line_number_area(self, rect, dy):
+        if dy:
+            self.line_numbers.scroll(0, dy)
+        else:
+            self.line_numbers.update(0, rect.y(), self.line_numbers.width(), rect.height())
+
+        if rect.contains(self.viewport().rect()):
+            self.update_line_number_width(0)
+
+    def resizeEvent(self, event):
+        super().resizeEvent(event)
+        rect = self.contentsRect()
+        rect.setWidth(self.line_number_width())
+        self.line_numbers.setGeometry(rect)
+
+    def highlight_current_line(self):
+        extra = []
+        if not self.isReadOnly():
+            selection = QTextCharFormat()
+            selection.setBackground(QColor("#111a24"))
+            selection.setProperty(QTextCharFormat.FullWidthSelection, True)
+            extra_selection = QTextEdit.ExtraSelection()
+            extra_selection.cursor = self.textCursor()
+            extra_selection.format = selection
+            extra.append(extra_selection)
+        self.setExtraSelections(extra)
+
+
+class ResultGraph(QWidget):
+    """Small dependency-free graph of numeric results."""
+
+    def __init__(self):
+        super().__init__()
+        self.values = []
+
+    def set_values(self, values):
+        self.values = values[-50:]
+        self.update()
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.Antialiasing)
+        painter.fillRect(self.rect(), QColor("#0b0f14"))
+
+        r = self.rect().adjusted(45, 20, -20, -35)
+        painter.setPen(QColor("#273442"))
+        painter.drawRect(r)
+
+        if not self.values:
+            painter.setPen(QColor("#647383"))
+            painter.drawText(r, Qt.AlignCenter, "No numeric results yet")
+            return
+
+        numeric = [v for v in self.values if math.isfinite(v)]
+        if not numeric:
+            return
+
+        lo = min(numeric)
+        hi = max(numeric)
+        if abs(hi - lo) < 1e-12:
+            lo -= 1
+            hi += 1
+
+        painter.setPen(QColor("#344454"))
+        for frac in (0.0, 0.5, 1.0):
+            y = int(r.bottom() - frac * r.height())
+            painter.drawLine(r.left(), y, r.right(), y)
+
+        painter.setPen(QColor("#5f6f80"))
+        painter.drawText(5, r.top() + 5, 35, 20, Qt.AlignRight, f"{hi:g}")
+        painter.drawText(5, r.bottom() - 15, 35, 20, Qt.AlignRight, f"{lo:g}")
+
+        if len(numeric) == 1:
+            x = r.center().x()
+            y = r.bottom() - (numeric[0] - lo) / (hi - lo) * r.height()
+            painter.setBrush(QColor("#58a6ff"))
+            painter.drawEllipse(int(x - 4), int(y - 4), 8, 8)
+            return
+
+        points = []
+        count = len(numeric)
+        for i, value in enumerate(numeric):
+            x = r.left() + i * r.width() / max(1, count - 1)
+            y = r.bottom() - (value - lo) / (hi - lo) * r.height()
+            points.append((x, y))
+
+        painter.setPen(QColor("#58a6ff"))
+        for a, b in zip(points, points[1:]):
+            painter.drawLine(int(a[0]), int(a[1]), int(b[0]), int(b[1]))
+
+        painter.setBrush(QColor("#58a6ff"))
+        for x, y in points:
+            painter.drawEllipse(int(x - 3), int(y - 3), 6, 6)
+
+
+class AbacusIDE(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.core = AbacusCore()
+        self.step = 0
+        self.results = []
+
+        self.setWindowTitle("Abacus IDE")
+        self.resize(1400, 850)
+        self.setMinimumSize(1050, 650)
+
+        self._build_main()
+        self._build_toolbar()
+        self._build_docks()
+        self._build_statusbar()
+
+        self._refresh_sidebars()
+        self.editor.setFocus()
+
+    def _build_toolbar(self):
+        toolbar = QToolBar()
+        toolbar.setMovable(False)
+        toolbar.setToolButtonStyle(Qt.ToolButtonTextOnly)
+        self.addToolBar(toolbar)
+
+        run = toolbar.addAction("▶  Run")
+        run.triggered.connect(self.run_document)
+
+        run_line = toolbar.addAction("Run line")
+        run_line.triggered.connect(self.run_current_line)
+
+        toolbar.addSeparator()
+
+        for symbol in ("+", "-", "*", "/", "(", ")", "[", "]", "="):
+            button = QPushButton(symbol)
+            button.setObjectName("operator")
+            button.clicked.connect(
+                lambda checked=False, s=symbol: self.insert_operator(s)
+            )
+            toolbar.addWidget(button)
+
+        toolbar.addSeparator()
+
+        clear = toolbar.addAction("Clear")
+        clear.triggered.connect(self.editor.clear)
+
+        toolbar.addSeparator()
+
+        reset = toolbar.addAction("Reset")
+        reset.triggered.connect(self.reset_abacus)
+
+    def _build_main(self):
+        self.tabs = QTabWidget()
+        self.setCentralWidget(self.tabs)
+
+        # Workspace tab
+        workspace = QWidget()
+        workspace_layout = QVBoxLayout(workspace)
+        workspace_layout.setContentsMargins(10, 10, 10, 10)
+        workspace_layout.setSpacing(8)
+
+        editor_header = QHBoxLayout()
+        label = QLabel("Expression editor")
+        label.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+
+        hint = QLabel(
+            "One command per line  •  # comments  •  Enter = run line"
+        )
+        hint.setStyleSheet("color: #657585;")
+
+        editor_header.addWidget(label)
+        editor_header.addStretch()
+        editor_header.addWidget(hint)
+        workspace_layout.addLayout(editor_header)
+
+        self.editor = CodeEditor()
+        self.highlighter = AbacusHighlighter(self.editor.document())
+        self.editor.setPlainText(
+            "# Example\n"
+            "alpha = 10\n"
+            "beta = 2\n"
+            "alpha + beta * 3\n"
+        )
+        workspace_layout.addWidget(self.editor, 1)
+
+        bottom = QFrame()
+        bottom.setObjectName("bottomCard")
+        bottom_layout = QHBoxLayout(bottom)
+        bottom_layout.setContentsMargins(10, 8, 10, 8)
+
+        bottom_layout.addWidget(QLabel("Quick input:"))
+
+        self.single_line = QLineEdit()
+        self.single_line.setObjectName("singleLine")
+        self.single_line.setPlaceholderText("Enter expression...")
+        self.single_line.returnPressed.connect(self.run_single_line)
+        bottom_layout.addWidget(self.single_line, 1)
+
+        execute = QPushButton("Execute")
+        execute.clicked.connect(self.run_single_line)
+        bottom_layout.addWidget(execute)
+
+        workspace_layout.addWidget(bottom)
+
+        self.tabs.addTab(workspace, "Workspace")
+
+        # Results tab
+        results_page = QWidget()
+        results_layout = QVBoxLayout(results_page)
+        results_layout.setContentsMargins(10, 10, 10, 10)
+
+        self.results_table = QTableWidget(0, 4)
+        self.results_table.setHorizontalHeaderLabels(
+            ["Step", "Expression", "Result", "Comment"]
+        )
+        self.results_table.horizontalHeader().setStretchLastSection(True)
+        self.results_table.setAlternatingRowColors(False)
+        results_layout.addWidget(self.results_table)
+
+        self.tabs.addTab(results_page, "Results")
+
+        # Graph tab
+        graph_page = QWidget()
+        graph_layout = QVBoxLayout(graph_page)
+        graph_layout.setContentsMargins(10, 10, 10, 10)
+
+        graph_title = QLabel("Numeric result history")
+        graph_title.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+        graph_layout.addWidget(graph_title)
+
+        self.graph = ResultGraph()
+        graph_layout.addWidget(self.graph, 1)
+
+        graph_info = QLabel(
+            "The graph uses numeric results from executed expressions."
+        )
+        graph_info.setStyleSheet("color: #657585;")
+        graph_layout.addWidget(graph_info)
+
+        self.tabs.addTab(graph_page, "Graph")
+
+    def _build_docks(self):
+        self.variables_dock = self._make_dock(
+            "Variables", self._make_list_widget()
+        )
+        self.functions_dock = self._make_dock(
+            "Functions", self._make_list_widget()
+        )
+        self.history_dock = self._make_dock(
+            "History", self._make_list_widget()
+        )
+
+        self.variables_list = self.variables_dock.widget()
+        self.functions_list = self.functions_dock.widget()
+        self.history_list = self.history_dock.widget()
+
+        self.addDockWidget(Qt.RightDockWidgetArea, self.variables_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.functions_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.history_dock)
+
+        self.tabifyDockWidget(self.variables_dock, self.functions_dock)
+        self.tabifyDockWidget(self.functions_dock, self.history_dock)
+        self.variables_dock.raise_()
+
+    def _make_list_widget(self):
+        return QListWidget()
+
+    def _make_dock(self, title, widget):
+        dock = QDockWidget(title, self)
+        dock.setAllowedAreas(
+            Qt.LeftDockWidgetArea | Qt.RightDockWidgetArea
+        )
+        dock.setFeatures(
+            QDockWidget.DockWidgetMovable
+            | QDockWidget.DockWidgetFloatable
+        )
+        dock.setWidget(widget)
+        return dock
+
+    def _build_statusbar(self):
+        self.status = QStatusBar()
+        self.setStatusBar(self.status)
+        self.status.showMessage("Ready")
+
+    def insert_operator(self, symbol):
+        self.editor.insertPlainText(symbol)
+        self.editor.setFocus()
+
+    def run_single_line(self):
+        text = self.single_line.text().strip()
+        if not text:
+            return
+
+        self._execute(text)
+        self.single_line.clear()
+
+    def run_current_line(self):
+        cursor = self.editor.textCursor()
+        cursor.select(cursor.LineUnderCursor)
+        line = cursor.selectedText().strip()
+
+        if line:
+            self._execute(line)
+
+    def run_document(self):
+        lines = self.editor.toPlainText().splitlines()
+
+        executed = 0
+        failed = 0
+
+        for line in lines:
+            line = line.strip()
+            if not line or line.startswith("#"):
+                continue
+
+            if self._execute(line):
+                executed += 1
+            else:
+                failed += 1
+
+        if failed:
+            self.status.showMessage(
+                f"Executed {executed} command(s), {failed} error(s)"
+            )
+        else:
+            self.status.showMessage(f"Executed {executed} command(s)")
+
+    def _execute(self, text):
+        self.step += 1
+
+        try:
+            result = self.core.parse_input(text)
+        except Exception as exc:
+            self.step -= 1
+            self.status.showMessage(f"Error: {exc}")
+            self.history_list.addItem(f"ERROR  {text}  →  {exc}")
+            return False
+
+        # Critical: assignments/functions return None, but their
+        # dictionaries are already changed. Refresh immediately.
+        self._refresh_sidebars()
+
+        if not result:
+            self.status.showMessage(f"Updated: {text}")
+            return True
+
+        original, _, value, comment = result
+        value_text = str(value)
+        comment_text = comment or ""
+
+        self.results.append(
+            {
+                "step": self.step,
+                "expression": original,
+                "result": value_text,
+                "comment": comment_text,
+            }
+        )
+
+        self.history_list.addItem(
+            f"{self.step}.  {original}  =  {value_text}"
+        )
+        self.history_list.scrollToBottom()
+
+        self._add_result_row(
+            self.step, original, value_text, comment_text
+        )
+
+        try:
+            numeric = float(value)
+        except (TypeError, ValueError):
+            numeric = None
+
+        if numeric is not None and math.isfinite(numeric):
+            self.graph.values.append(numeric)
+            self.graph.set_values(self.graph.values)
+
+        self.status.showMessage(f"Result: {value_text}")
+        return True
+
+    def _add_result_row(self, step, expression, result, comment):
+        row = self.results_table.rowCount()
+        self.results_table.insertRow(row)
+
+        values = [str(step), expression, result, comment]
+
+        for col, value in enumerate(values):
+            self.results_table.setItem(
+                row, col, QTableWidgetItem(value)
+            )
+
+        self.results_table.resizeColumnsToContents()
+        self.results_table.scrollToBottom()
+
+    def _refresh_sidebars(self):
+        self.variables_list.clear()
+
+        for key, value in self.core.get_vars().items():
+            self.variables_list.addItem(f"{key}    =    {value}")
+
+        self.functions_list.clear()
+
+        for key, value in self.core.get_funcs().items():
+            self.functions_list.addItem(f"{key}    =    {value}")
+
+    def reset_abacus(self):
+        self.core = AbacusCore()
+        self.step = 0
+        self.results.clear()
+
+        self.variables_list.clear()
+        self.functions_list.clear()
+        self.history_list.clear()
+        self.results_table.setRowCount(0)
+
+        self.graph.set_values([])
+        self.status.showMessage("Abacus state reset")
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+    app.setStyleSheet(STYLE)
+
+    window = AbacusIDE()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/abacus_ide_checked_final.py b/abacus_ide_checked_final.py
new file mode 100644
index 0000000..5427fcf
--- /dev/null
+++ b/abacus_ide_checked_final.py
@@ -0,0 +1,1091 @@
+import json
+import math
+import sys
+
+from PySide6.QtCore import Qt, QSize, QStringListModel
+from PySide6.QtGui import (
+    QColor,
+    QFont,
+    QPainter,
+    QSyntaxHighlighter,
+    QTextCharFormat,
+    QTextCursor,
+)
+from PySide6.QtWidgets import (
+    QApplication,
+    QDockWidget,
+    QFrame,
+    QCompleter,
+    QFileDialog,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListWidget,
+    QMainWindow,
+    QPlainTextEdit,
+    QTextEdit,
+    QPushButton,
+    QStatusBar,
+    QTabWidget,
+    QTableWidget,
+    QTableWidgetItem,
+    QToolBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+from abacus_core import AbacusCore
+
+
+STYLE = """
+QMainWindow, QWidget {
+    background: #0d1117;
+    color: #e6edf3;
+    font-family: "Segoe UI";
+    font-size: 13px;
+}
+
+QToolBar {
+    background: #111820;
+    border: 0;
+    border-bottom: 1px solid #202a36;
+    spacing: 5px;
+    padding: 6px 8px;
+}
+
+QToolButton {
+    color: #c9d1d9;
+    background: transparent;
+    border-radius: 7px;
+    padding: 7px 10px;
+}
+
+QToolButton:hover {
+    background: #1b2531;
+    color: #ffffff;
+}
+
+QTabWidget::pane {
+    border: 1px solid #202a36;
+    background: #0d1117;
+}
+
+QTabBar::tab {
+    background: #111820;
+    color: #7d8b99;
+    border: 1px solid #202a36;
+    border-bottom: none;
+    padding: 9px 16px;
+    margin-right: 2px;
+}
+
+QTabBar::tab:selected {
+    background: #17212c;
+    color: #f0f6fc;
+}
+
+QDockWidget {
+    color: #aeb9c6;
+    titlebar-close-icon: none;
+    titlebar-normal-icon: none;
+}
+
+QDockWidget::title {
+    background: #111820;
+    border-bottom: 1px solid #202a36;
+    padding: 9px 11px;
+    font-weight: 700;
+}
+
+QFrame#editorCard, QFrame#bottomCard {
+    background: #111820;
+    border: 1px solid #202a36;
+    border-radius: 10px;
+}
+
+QPlainTextEdit {
+    background: #0b0f14;
+    color: #d6deea;
+    border: 1px solid #202a36;
+    border-radius: 9px;
+    selection-background-color: #244a7d;
+    padding: 8px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+    font-size: 14px;
+}
+
+QLineEdit#singleLine {
+    background: #0b0f14;
+    color: #f0f6fc;
+    border: 1px solid #303b48;
+    border-radius: 9px;
+    padding: 9px 11px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+}
+
+QLineEdit#singleLine:focus {
+    border: 1px solid #3b82f6;
+}
+
+QPushButton {
+    background: #2563eb;
+    color: white;
+    border: none;
+    border-radius: 8px;
+    padding: 8px 13px;
+    font-weight: 700;
+}
+
+QPushButton:hover {
+    background: #3475ef;
+}
+
+QPushButton#operator {
+    background: #1b2531;
+    color: #cbd5e1;
+    border: 1px solid #293543;
+    min-width: 34px;
+}
+
+QPushButton#operator:hover {
+    background: #253344;
+    color: #ffffff;
+}
+
+QPushButton#secondary {
+    background: #1b2531;
+    color: #b9c4d0;
+    border: 1px solid #293543;
+}
+
+QListWidget, QTableWidget {
+    background: #0d131a;
+    color: #cbd5e1;
+    border: 1px solid #202a36;
+    border-radius: 8px;
+    outline: none;
+}
+
+QListWidget::item {
+    padding: 7px 8px;
+    border-radius: 6px;
+}
+
+QListWidget::item:hover {
+    background: #17212c;
+}
+
+QListWidget::item:selected {
+    background: #1c3153;
+    color: #ffffff;
+}
+
+QHeaderView::section {
+    background: #161f29;
+    color: #9aa8b7;
+    border: none;
+    border-right: 1px solid #202a36;
+    border-bottom: 1px solid #202a36;
+    padding: 7px;
+}
+
+QTableWidget::item {
+    padding: 6px;
+    border-bottom: 1px solid #18212b;
+}
+
+QStatusBar {
+    background: #0b0f14;
+    color: #7d8b99;
+    border-top: 1px solid #202a36;
+}
+
+QScrollBar:vertical {
+    background: #0d131a;
+    width: 9px;
+}
+
+QScrollBar::handle:vertical {
+    background: #303c4a;
+    border-radius: 4px;
+    min-height: 25px;
+}
+
+QScrollBar::add-line:vertical,
+QScrollBar::sub-line:vertical {
+    height: 0;
+}
+"""
+
+
+class AbacusHighlighter(QSyntaxHighlighter):
+    def __init__(self, document):
+        super().__init__(document)
+
+        self.number = QTextCharFormat()
+        self.number.setForeground(QColor("#79c0ff"))
+
+        self.operator = QTextCharFormat()
+        self.operator.setForeground(QColor("#ff7b72"))
+
+        self.comment = QTextCharFormat()
+        self.comment.setForeground(QColor("#6e7681"))
+        self.comment.setFontItalic(True)
+
+        self.assignment = QTextCharFormat()
+        self.assignment.setForeground(QColor("#d2a8ff"))
+
+        self.keyword = QTextCharFormat()
+        self.keyword.setForeground(QColor("#ffa657"))
+
+    def highlightBlock(self, text):
+        # Comments
+        comment_pos = text.find("#")
+        if comment_pos >= 0:
+            self.setFormat(comment_pos, len(text) - comment_pos, self.comment)
+            code = text[:comment_pos]
+        else:
+            code = text
+
+        # Numbers
+        i = 0
+        while i < len(code):
+            if code[i].isdigit() or (
+                code[i] == "." and i + 1 < len(code) and code[i + 1].isdigit()
+            ):
+                start = i
+                i += 1
+                while i < len(code) and (code[i].isdigit() or code[i] == "."):
+                    i += 1
+                self.setFormat(start, i - start, self.number)
+            else:
+                i += 1
+
+        for char in "+-*/=():[];":
+            start = 0
+            while True:
+                pos = code.find(char, start)
+                if pos < 0:
+                    break
+                self.setFormat(pos, 1, self.operator)
+                start = pos + 1
+
+        # Function definitions: name before ':'
+        colon = code.find(":")
+        if colon > 0:
+            name = code[:colon].strip()
+            if name:
+                pos = code.find(name)
+                self.setFormat(pos, len(name), self.keyword)
+
+
+class LineNumberArea(QWidget):
+    def __init__(self, editor):
+        super().__init__(editor)
+        self.editor = editor
+
+    def sizeHint(self):
+        return QSize(self.editor.line_number_width(), 0)
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.fillRect(event.rect(), QColor("#0f151c"))
+
+        block = self.editor.firstVisibleBlock()
+        block_number = block.blockNumber()
+        top = int(
+            self.editor.blockBoundingGeometry(block).translated(
+                self.editor.contentOffset()
+            ).top()
+        )
+        bottom = top + int(self.editor.blockBoundingRect(block).height())
+
+        while block.isValid() and top <= event.rect().bottom():
+            if block.isVisible() and bottom >= event.rect().top():
+                painter.setPen(QColor("#596878"))
+                painter.drawText(
+                    0,
+                    top,
+                    self.width() - 7,
+                    self.editor.fontMetrics().height(),
+                    Qt.AlignRight,
+                    str(block_number + 1),
+                )
+
+            block = block.next()
+            top = bottom
+            bottom = top + int(self.editor.blockBoundingRect(block).height())
+            block_number += 1
+
+
+class CodeEditor(QPlainTextEdit):
+    def __init__(self):
+        super().__init__()
+
+        self.line_numbers = LineNumberArea(self)
+        self.error_lines = {}
+        self.completer = None
+
+        self.blockCountChanged.connect(self.update_line_number_width)
+        self.updateRequest.connect(self.update_line_number_area)
+        self.cursorPositionChanged.connect(self.highlight_current_line)
+
+        self.update_line_number_width(0)
+        self.highlight_current_line()
+
+        font = QFont("JetBrains Mono", 11)
+        font.setStyleHint(QFont.Monospace)
+        self.setFont(font)
+        self.setTabStopDistance(
+            self.fontMetrics().horizontalAdvance(" ") * 4
+        )
+
+    def line_number_width(self):
+        digits = len(str(max(1, self.blockCount())))
+        return 12 + self.fontMetrics().horizontalAdvance("9") * digits
+
+    def update_line_number_width(self, _):
+        self.setViewportMargins(self.line_number_width(), 0, 0, 0)
+
+    def update_line_number_area(self, rect, dy):
+        if dy:
+            self.line_numbers.scroll(0, dy)
+        else:
+            self.line_numbers.update(
+                0,
+                rect.y(),
+                self.line_numbers.width(),
+                rect.height(),
+            )
+
+        if rect.contains(self.viewport().rect()):
+            self.update_line_number_width(0)
+
+    def resizeEvent(self, event):
+        super().resizeEvent(event)
+        rect = self.contentsRect()
+        rect.setWidth(self.line_number_width())
+        self.line_numbers.setGeometry(rect)
+
+    def highlight_current_line(self):
+        extra = []
+
+        if not self.isReadOnly():
+            selection = QTextCharFormat()
+            selection.setBackground(QColor("#111a24"))
+            selection.setProperty(
+                QTextCharFormat.FullWidthSelection,
+                True,
+            )
+
+            extra_selection = QTextEdit.ExtraSelection()
+            extra_selection.cursor = self.textCursor()
+            extra_selection.format = selection
+            extra.append(extra_selection)
+
+        # Error lines always get a stronger red background.
+        for line_number, message in self.error_lines.items():
+            block = self.document().findBlockByNumber(line_number - 1)
+            if not block.isValid():
+                continue
+
+            cursor = self.textCursor()
+            cursor.setPosition(block.position())
+            cursor.setPosition(
+                block.position() + max(1, block.length() - 1),
+                QTextCursor.KeepAnchor,
+            )
+
+            selection = QTextCharFormat()
+            selection.setBackground(QColor("#4a1f25"))
+            selection.setForeground(QColor("#ffb4b4"))
+            selection.setProperty(
+                QTextCharFormat.FullWidthSelection,
+                True,
+            )
+
+            extra_selection = QTextEdit.ExtraSelection()
+            extra_selection.cursor = cursor
+            extra_selection.format = selection
+            extra.append(extra_selection)
+
+        self.setExtraSelections(extra)
+
+        self.line_numbers.update()
+
+    def set_error_lines(self, errors):
+        self.error_lines = dict(errors)
+        self.highlight_current_line()
+
+    def clear_error_lines(self):
+        self.error_lines.clear()
+        self.highlight_current_line()
+
+    def set_completer(self, completer):
+        self.completer = completer
+        completer.setWidget(self)
+        completer.setCompletionMode(QCompleter.PopupCompletion)
+        completer.setCaseSensitivity(Qt.CaseInsensitive)
+        completer.activated.connect(self.insert_completion)
+
+    def insert_completion(self, completion):
+        prefix = self.completion_prefix()
+        cursor = self.textCursor()
+
+        if prefix:
+            cursor.movePosition(
+                QTextCursor.Left,
+                QTextCursor.KeepAnchor,
+                len(prefix),
+            )
+            cursor.insertText(completion)
+        else:
+            cursor.insertText(completion)
+
+        self.setTextCursor(cursor)
+
+    def completion_prefix(self):
+        cursor = self.textCursor()
+        text = cursor.block().text()
+        pos = cursor.positionInBlock()
+
+        start = pos
+        while start > 0:
+            char = text[start - 1]
+            if not (char.isalnum() or char == "_"):
+                break
+            start -= 1
+
+        return text[start:pos]
+
+    def show_completion(self, show_all=False):
+        if not self.completer:
+            return
+
+        prefix = self.completion_prefix()
+        if not prefix and not show_all:
+            self.completer.popup().hide()
+            return
+
+        self.completer.setCompletionPrefix(prefix)
+
+        if show_all:
+            self.completer.setCompletionPrefix("")
+
+        if self.completer.completionCount() == 0:
+            self.completer.popup().hide()
+            return
+
+        rect = self.cursorRect()
+        rect.setWidth(
+            self.completer.popup().sizeHintForColumn(0)
+            + self.completer.popup().verticalScrollBar().sizeHint().width()
+        )
+        self.completer.complete(rect)
+
+    def keyPressEvent(self, event):
+        if self.completer and self.completer.popup().isVisible():
+            if event.key() in (
+                Qt.Key_Enter,
+                Qt.Key_Return,
+                Qt.Key_Tab,
+                Qt.Key_Backtab,
+            ):
+                event.ignore()
+                return
+
+            if event.key() == Qt.Key_Escape:
+                self.completer.popup().hide()
+                return
+
+        if (
+            event.key() == Qt.Key_Space
+            and event.modifiers() & Qt.ControlModifier
+        ):
+            self.show_completion(show_all=True)
+            return
+
+        super().keyPressEvent(event)
+
+        if self.completer:
+            self.show_completion()
+
+class ResultGraph(QWidget):
+    """Small dependency-free graph of numeric results."""
+
+    def __init__(self):
+        super().__init__()
+        self.values = []
+
+    def set_values(self, values):
+        self.values = values[-50:]
+        self.update()
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.Antialiasing)
+        painter.fillRect(self.rect(), QColor("#0b0f14"))
+
+        r = self.rect().adjusted(45, 20, -20, -35)
+        painter.setPen(QColor("#273442"))
+        painter.drawRect(r)
+
+        if not self.values:
+            painter.setPen(QColor("#647383"))
+            painter.drawText(r, Qt.AlignCenter, "No numeric results yet")
+            return
+
+        numeric = [v for v in self.values if math.isfinite(v)]
+        if not numeric:
+            return
+
+        lo = min(numeric)
+        hi = max(numeric)
+        if abs(hi - lo) < 1e-12:
+            lo -= 1
+            hi += 1
+
+        painter.setPen(QColor("#344454"))
+        for frac in (0.0, 0.5, 1.0):
+            y = int(r.bottom() - frac * r.height())
+            painter.drawLine(r.left(), y, r.right(), y)
+
+        painter.setPen(QColor("#5f6f80"))
+        painter.drawText(5, r.top() + 5, 35, 20, Qt.AlignRight, f"{hi:g}")
+        painter.drawText(5, r.bottom() - 15, 35, 20, Qt.AlignRight, f"{lo:g}")
+
+        if len(numeric) == 1:
+            x = r.center().x()
+            y = r.bottom() - (numeric[0] - lo) / (hi - lo) * r.height()
+            painter.setBrush(QColor("#58a6ff"))
+            painter.drawEllipse(int(x - 4), int(y - 4), 8, 8)
+            return
+
+        points = []
+        count = len(numeric)
+        for i, value in enumerate(numeric):
+            x = r.left() + i * r.width() / max(1, count - 1)
+            y = r.bottom() - (value - lo) / (hi - lo) * r.height()
+            points.append((x, y))
+
+        painter.setPen(QColor("#58a6ff"))
+        for a, b in zip(points, points[1:]):
+            painter.drawLine(int(a[0]), int(a[1]), int(b[0]), int(b[1]))
+
+        painter.setBrush(QColor("#58a6ff"))
+        for x, y in points:
+            painter.drawEllipse(int(x - 3), int(y - 3), 6, 6)
+
+
+class AbacusIDE(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.core = AbacusCore()
+        self.step = 0
+        self.results = []
+
+        self.setWindowTitle("Abacus IDE")
+        self.resize(1400, 850)
+        self.setMinimumSize(1050, 650)
+
+        self._build_main()
+        self._build_menu()
+        self._build_toolbar()
+        self._build_docks()
+        self._build_statusbar()
+
+        self._refresh_sidebars()
+        self.editor.setFocus()
+
+    def _build_menu(self):
+        menu = self.menuBar()
+
+        file_menu = menu.addMenu("File")
+
+        export_action = file_menu.addAction("Export history to JSON...")
+        export_action.triggered.connect(self.export_history)
+
+        import_action = file_menu.addAction("Import history from JSON...")
+        import_action.triggered.connect(self.import_history)
+
+        file_menu.addSeparator()
+
+        reset_action = file_menu.addAction("Reset Abacus")
+        reset_action.triggered.connect(self.reset_abacus)
+
+        file_menu.addSeparator()
+
+        exit_action = file_menu.addAction("Exit")
+        exit_action.triggered.connect(self.close)
+
+        edit_menu = menu.addMenu("Edit")
+        clear_errors = edit_menu.addAction("Clear error highlighting")
+        clear_errors.triggered.connect(self.editor.clear_error_lines)
+
+    def _build_toolbar(self):
+        toolbar = QToolBar()
+        toolbar.setMovable(False)
+        toolbar.setToolButtonStyle(Qt.ToolButtonTextOnly)
+        self.addToolBar(toolbar)
+
+        run = toolbar.addAction("▶  Run")
+        run.triggered.connect(self.run_document)
+
+        run_line = toolbar.addAction("Run line")
+        run_line.triggered.connect(self.run_current_line)
+
+        toolbar.addSeparator()
+
+        for symbol in ("+", "-", "*", "/", "(", ")", "[", "]", "="):
+            button = QPushButton(symbol)
+            button.setObjectName("operator")
+            button.clicked.connect(
+                lambda checked=False, s=symbol: self.insert_operator(s)
+            )
+            toolbar.addWidget(button)
+
+        toolbar.addSeparator()
+
+        clear = toolbar.addAction("Clear")
+        clear.triggered.connect(self.editor.clear)
+
+        toolbar.addSeparator()
+
+        reset = toolbar.addAction("Reset")
+        reset.triggered.connect(self.reset_abacus)
+
+    def _build_main(self):
+        self.tabs = QTabWidget()
+        self.setCentralWidget(self.tabs)
+
+        # Workspace tab
+        workspace = QWidget()
+        workspace_layout = QVBoxLayout(workspace)
+        workspace_layout.setContentsMargins(10, 10, 10, 10)
+        workspace_layout.setSpacing(8)
+
+        editor_header = QHBoxLayout()
+        label = QLabel("Expression editor")
+        label.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+
+        hint = QLabel(
+            "One command per line  •  # comments  •  Enter = run line"
+        )
+        hint.setStyleSheet("color: #657585;")
+
+        editor_header.addWidget(label)
+        editor_header.addStretch()
+        editor_header.addWidget(hint)
+        workspace_layout.addLayout(editor_header)
+
+        self.editor = CodeEditor()
+        self.highlighter = AbacusHighlighter(self.editor.document())
+
+        self.completion_model = QStringListModel()
+        self.completer = QCompleter(self.completion_model, self)
+        self.editor.set_completer(self.completer)
+
+        self.editor.setPlainText(
+            "# Example\n"
+            "alpha = 10\n"
+            "beta = 2\n"
+            "alpha + beta * 3\n"
+        )
+        workspace_layout.addWidget(self.editor, 1)
+
+        bottom = QFrame()
+        bottom.setObjectName("bottomCard")
+        bottom_layout = QHBoxLayout(bottom)
+        bottom_layout.setContentsMargins(10, 8, 10, 8)
+
+        bottom_layout.addWidget(QLabel("Quick input:"))
+
+        self.single_line = QLineEdit()
+        self.single_line.setObjectName("singleLine")
+        self.single_line.setPlaceholderText("Enter expression...")
+        self.single_line.returnPressed.connect(self.run_single_line)
+        bottom_layout.addWidget(self.single_line, 1)
+
+        execute = QPushButton("Execute")
+        execute.clicked.connect(self.run_single_line)
+        bottom_layout.addWidget(execute)
+
+        workspace_layout.addWidget(bottom)
+
+        self.tabs.addTab(workspace, "Workspace")
+
+        # Results tab
+        results_page = QWidget()
+        results_layout = QVBoxLayout(results_page)
+        results_layout.setContentsMargins(10, 10, 10, 10)
+
+        self.results_table = QTableWidget(0, 4)
+        self.results_table.setHorizontalHeaderLabels(
+            ["Step", "Expression", "Result", "Comment"]
+        )
+        self.results_table.horizontalHeader().setStretchLastSection(True)
+        self.results_table.setAlternatingRowColors(False)
+        results_layout.addWidget(self.results_table)
+
+        self.tabs.addTab(results_page, "Results")
+
+        # Graph tab
+        graph_page = QWidget()
+        graph_layout = QVBoxLayout(graph_page)
+        graph_layout.setContentsMargins(10, 10, 10, 10)
+
+        graph_title = QLabel("Numeric result history")
+        graph_title.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+        graph_layout.addWidget(graph_title)
+
+        self.graph = ResultGraph()
+        graph_layout.addWidget(self.graph, 1)
+
+        graph_info = QLabel(
+            "The graph uses numeric results from executed expressions."
+        )
+        graph_info.setStyleSheet("color: #657585;")
+        graph_layout.addWidget(graph_info)
+
+        self.tabs.addTab(graph_page, "Graph")
+
+    def _build_docks(self):
+        self.variables_dock = self._make_dock(
+            "Variables", self._make_list_widget()
+        )
+        self.functions_dock = self._make_dock(
+            "Functions", self._make_list_widget()
+        )
+        self.history_dock = self._make_dock(
+            "History", self._make_list_widget()
+        )
+
+        self.variables_list = self.variables_dock.widget()
+        self.functions_list = self.functions_dock.widget()
+        self.history_list = self.history_dock.widget()
+
+        self.addDockWidget(Qt.RightDockWidgetArea, self.variables_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.functions_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.history_dock)
+
+        self.tabifyDockWidget(self.variables_dock, self.functions_dock)
+        self.tabifyDockWidget(self.functions_dock, self.history_dock)
+        self.variables_dock.raise_()
+
+    def _make_list_widget(self):
+        return QListWidget()
+
+    def _make_dock(self, title, widget):
+        dock = QDockWidget(title, self)
+        dock.setAllowedAreas(
+            Qt.LeftDockWidgetArea | Qt.RightDockWidgetArea
+        )
+        dock.setFeatures(
+            QDockWidget.DockWidgetMovable
+            | QDockWidget.DockWidgetFloatable
+        )
+        dock.setWidget(widget)
+        return dock
+
+    def _build_statusbar(self):
+        self.status = QStatusBar()
+        self.setStatusBar(self.status)
+        self.status.showMessage("Ready")
+
+    def insert_operator(self, symbol):
+        self.editor.insertPlainText(symbol)
+        self.editor.setFocus()
+
+    def run_single_line(self):
+        text = self.single_line.text().strip()
+        if not text:
+            return
+
+        self._execute(text)
+        self.single_line.clear()
+
+    def run_current_line(self):
+        cursor = self.editor.textCursor()
+        cursor.select(cursor.LineUnderCursor)
+        line = cursor.selectedText().strip()
+
+        if line:
+            self.editor.clear_error_lines()
+            line_number = cursor.blockNumber() + 1
+            self._execute(line, line_number)
+
+    def run_document(self):
+        self.editor.clear_error_lines()
+        lines = self.editor.toPlainText().splitlines()
+
+        executed = 0
+        failed = 0
+
+        for line_index, line in enumerate(lines, start=1):
+            stripped = line.strip()
+            if not stripped or stripped.startswith("#"):
+                continue
+
+            if self._execute(stripped, line_index):
+                executed += 1
+            else:
+                failed += 1
+
+        if failed:
+            self.status.showMessage(
+                f"Executed {executed} command(s), {failed} error(s)"
+            )
+        else:
+            self.status.showMessage(f"Executed {executed} command(s)")
+
+    def _execute(self, text, line_number=None):
+        self.step += 1
+
+        try:
+            result = self.core.parse_input(text)
+        except Exception as exc:
+            self.step -= 1
+            self.status.showMessage(f"Error: {exc}")
+
+            if line_number is not None:
+                self.editor.set_error_lines({
+                    line_number: str(exc),
+                })
+
+            self.history_list.addItem(
+                f"ERROR  line {line_number or '?'}  {text}  →  {exc}"
+            )
+            return False
+
+        # Critical: assignments/functions return None, but their
+        # dictionaries are already changed. Refresh immediately.
+        self._refresh_sidebars()
+
+        if not result:
+            self.status.showMessage(f"Updated: {text}")
+            return True
+
+        original, _, value, comment = result
+        value_text = str(value)
+        comment_text = comment or ""
+
+        self.results.append(
+            {
+                "step": self.step,
+                "expression": original,
+                "result": value_text,
+                "comment": comment_text,
+            }
+        )
+
+        self.history_list.addItem(
+            f"{self.step}.  {original}  =  {value_text}"
+        )
+        self.history_list.scrollToBottom()
+
+        self._add_result_row(
+            self.step, original, value_text, comment_text
+        )
+
+        try:
+            numeric = float(value)
+        except (TypeError, ValueError):
+            numeric = None
+
+        if numeric is not None and math.isfinite(numeric):
+            self.graph.values.append(numeric)
+            self.graph.set_values(self.graph.values)
+
+        self.status.showMessage(f"Result: {value_text}")
+        return True
+
+    def _add_result_row(self, step, expression, result, comment):
+        row = self.results_table.rowCount()
+        self.results_table.insertRow(row)
+
+        values = [str(step), expression, result, comment]
+
+        for col, value in enumerate(values):
+            self.results_table.setItem(
+                row, col, QTableWidgetItem(value)
+            )
+
+        self.results_table.resizeColumnsToContents()
+        self.results_table.scrollToBottom()
+
+    def _refresh_sidebars(self):
+        self.variables_list.clear()
+
+        for key, value in self.core.get_vars().items():
+            self.variables_list.addItem(f"{key}    =    {value}")
+
+        self.functions_list.clear()
+
+        functions = self.core.get_funcs()
+
+        for key, value in functions.items():
+            self.functions_list.addItem(f"{key}    =    {value}")
+
+        names = list(self.core.get_vars().keys()) + list(functions.keys())
+        self.completion_model.setStringList(sorted(set(names)))
+
+    def export_history(self):
+        path, _ = QFileDialog.getSaveFileName(
+            self,
+            "Export history",
+            "abacus_history.json",
+            "JSON files (*.json)",
+        )
+        if not path:
+            return
+
+        data = {
+            "format": "abacus-history",
+            "version": 1,
+            "step": self.step,
+            "document": self.editor.toPlainText(),
+            "variables": self.core.get_vars(),
+            "functions": self.core.get_funcs(),
+            "history": [
+                self.history_list.item(i).text()
+                for i in range(self.history_list.count())
+            ],
+            "results": self.results,
+            "graph_values": self.graph.values,
+        }
+
+        try:
+            with open(path, "w", encoding="utf-8") as file:
+                json.dump(
+                    data,
+                    file,
+                    ensure_ascii=False,
+                    indent=2,
+                )
+        except OSError as exc:
+            self.status.showMessage(f"Export error: {exc}")
+            return
+
+        self.status.showMessage(f"History exported: {path}")
+
+    def import_history(self):
+        path, _ = QFileDialog.getOpenFileName(
+            self,
+            "Import history",
+            "",
+            "JSON files (*.json)",
+        )
+        if not path:
+            return
+
+        try:
+            with open(path, "r", encoding="utf-8") as file:
+                data = json.load(file)
+
+            if data.get("format") != "abacus-history":
+                raise ValueError("Not an Abacus history file")
+
+            if data.get("version") != 1:
+                raise ValueError(
+                    f"Unsupported history version: {data.get('version')}"
+                )
+
+            history = data.get("history", [])
+            results = data.get("results", [])
+            graph_values = data.get("graph_values", [])
+            variables = data.get("variables", {})
+            functions = data.get("functions", {})
+            document = data.get("document", "")
+            step = int(data.get("step", len(results)))
+
+            if not isinstance(history, list):
+                raise ValueError("Invalid history data")
+            if not isinstance(results, list):
+                raise ValueError("Invalid results data")
+            if not all(isinstance(item, dict) for item in results):
+                raise ValueError("Invalid result item")
+            if not isinstance(graph_values, list):
+                raise ValueError("Invalid graph data")
+            if not isinstance(variables, dict):
+                raise ValueError("Invalid variables data")
+            if not isinstance(functions, dict):
+                raise ValueError("Invalid functions data")
+            if not isinstance(document, str):
+                raise ValueError("Invalid document data")
+
+            imported_graph_values = []
+            for value in graph_values:
+                number = float(value)
+                if not math.isfinite(number):
+                    raise ValueError("Graph contains a non-finite value")
+                imported_graph_values.append(number)
+
+        except (OSError, ValueError, TypeError, json.JSONDecodeError) as exc:
+            self.status.showMessage(f"Import error: {exc}")
+            return
+
+        self.step = step
+        self.results = results
+
+        self.core = AbacusCore()
+        self.core.get_vars().clear()
+        self.core.get_vars().update(variables)
+        self.core.get_funcs().clear()
+        self.core.get_funcs().update(functions)
+
+        self.history_list.clear()
+        self.history_list.addItems(
+            str(item) for item in history
+        )
+
+        self.results_table.setRowCount(0)
+        for item in self.results:
+            self._add_result_row(
+                item.get("step", ""),
+                item.get("expression", ""),
+                item.get("result", ""),
+                item.get("comment", ""),
+            )
+
+        self.graph.set_values(imported_graph_values)
+
+        self.editor.setPlainText(document)
+        self.editor.clear_error_lines()
+        self._refresh_sidebars()
+
+        self.status.showMessage(f"History imported: {path}")
+
+    def reset_abacus(self):
+        self.core = AbacusCore()
+        self.step = 0
+        self.results.clear()
+
+        self.variables_list.clear()
+        self.functions_list.clear()
+        self.history_list.clear()
+        self.results_table.setRowCount(0)
+
+        self.graph.set_values([])
+        self.editor.clear_error_lines()
+        self._refresh_sidebars()
+        self.status.showMessage("Abacus state reset")
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+    app.setStyleSheet(STYLE)
+
+    window = AbacusIDE()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/abacus_ide_fixed.py b/abacus_ide_fixed.py
new file mode 100644
index 0000000..a9c089e
--- /dev/null
+++ b/abacus_ide_fixed.py
@@ -0,0 +1,761 @@
+import math
+import sys
+
+from PySide6.QtCore import Qt, QRect, QSize
+from PySide6.QtGui import (
+    QColor,
+    QFont,
+    QPainter,
+    QSyntaxHighlighter,
+    QTextCharFormat,
+)
+from PySide6.QtWidgets import (
+    QApplication,
+    QDockWidget,
+    QFrame,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListWidget,
+    QMainWindow,
+    QPlainTextEdit,
+    QPushButton,
+    QSplitter,
+    QStatusBar,
+    QTabWidget,
+    QTableWidget,
+    QTableWidgetItem,
+    QToolBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+from abacus_core import AbacusCore
+
+
+STYLE = """
+QMainWindow, QWidget {
+    background: #0d1117;
+    color: #e6edf3;
+    font-family: "Segoe UI";
+    font-size: 13px;
+}
+
+QToolBar {
+    background: #111820;
+    border: 0;
+    border-bottom: 1px solid #202a36;
+    spacing: 5px;
+    padding: 6px 8px;
+}
+
+QToolButton {
+    color: #c9d1d9;
+    background: transparent;
+    border-radius: 7px;
+    padding: 7px 10px;
+}
+
+QToolButton:hover {
+    background: #1b2531;
+    color: #ffffff;
+}
+
+QTabWidget::pane {
+    border: 1px solid #202a36;
+    background: #0d1117;
+}
+
+QTabBar::tab {
+    background: #111820;
+    color: #7d8b99;
+    border: 1px solid #202a36;
+    border-bottom: none;
+    padding: 9px 16px;
+    margin-right: 2px;
+}
+
+QTabBar::tab:selected {
+    background: #17212c;
+    color: #f0f6fc;
+}
+
+QDockWidget {
+    color: #aeb9c6;
+    titlebar-close-icon: none;
+    titlebar-normal-icon: none;
+}
+
+QDockWidget::title {
+    background: #111820;
+    border-bottom: 1px solid #202a36;
+    padding: 9px 11px;
+    font-weight: 700;
+}
+
+QFrame#editorCard, QFrame#bottomCard {
+    background: #111820;
+    border: 1px solid #202a36;
+    border-radius: 10px;
+}
+
+QPlainTextEdit {
+    background: #0b0f14;
+    color: #d6deea;
+    border: 1px solid #202a36;
+    border-radius: 9px;
+    selection-background-color: #244a7d;
+    padding: 8px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+    font-size: 14px;
+}
+
+QLineEdit#singleLine {
+    background: #0b0f14;
+    color: #f0f6fc;
+    border: 1px solid #303b48;
+    border-radius: 9px;
+    padding: 9px 11px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+}
+
+QLineEdit#singleLine:focus {
+    border: 1px solid #3b82f6;
+}
+
+QPushButton {
+    background: #2563eb;
+    color: white;
+    border: none;
+    border-radius: 8px;
+    padding: 8px 13px;
+    font-weight: 700;
+}
+
+QPushButton:hover {
+    background: #3475ef;
+}
+
+QPushButton#operator {
+    background: #1b2531;
+    color: #cbd5e1;
+    border: 1px solid #293543;
+    min-width: 34px;
+}
+
+QPushButton#operator:hover {
+    background: #253344;
+    color: #ffffff;
+}
+
+QPushButton#secondary {
+    background: #1b2531;
+    color: #b9c4d0;
+    border: 1px solid #293543;
+}
+
+QListWidget, QTableWidget {
+    background: #0d131a;
+    color: #cbd5e1;
+    border: 1px solid #202a36;
+    border-radius: 8px;
+    outline: none;
+}
+
+QListWidget::item {
+    padding: 7px 8px;
+    border-radius: 6px;
+}
+
+QListWidget::item:hover {
+    background: #17212c;
+}
+
+QListWidget::item:selected {
+    background: #1c3153;
+    color: #ffffff;
+}
+
+QHeaderView::section {
+    background: #161f29;
+    color: #9aa8b7;
+    border: none;
+    border-right: 1px solid #202a36;
+    border-bottom: 1px solid #202a36;
+    padding: 7px;
+}
+
+QTableWidget::item {
+    padding: 6px;
+    border-bottom: 1px solid #18212b;
+}
+
+QStatusBar {
+    background: #0b0f14;
+    color: #7d8b99;
+    border-top: 1px solid #202a36;
+}
+
+QScrollBar:vertical {
+    background: #0d131a;
+    width: 9px;
+}
+
+QScrollBar::handle:vertical {
+    background: #303c4a;
+    border-radius: 4px;
+    min-height: 25px;
+}
+
+QScrollBar::add-line:vertical,
+QScrollBar::sub-line:vertical {
+    height: 0;
+}
+"""
+
+
+class AbacusHighlighter(QSyntaxHighlighter):
+    def __init__(self, document):
+        super().__init__(document)
+
+        self.number = QTextCharFormat()
+        self.number.setForeground(QColor("#79c0ff"))
+
+        self.operator = QTextCharFormat()
+        self.operator.setForeground(QColor("#ff7b72"))
+
+        self.comment = QTextCharFormat()
+        self.comment.setForeground(QColor("#6e7681"))
+        self.comment.setFontItalic(True)
+
+        self.assignment = QTextCharFormat()
+        self.assignment.setForeground(QColor("#d2a8ff"))
+
+        self.keyword = QTextCharFormat()
+        self.keyword.setForeground(QColor("#ffa657"))
+
+    def highlightBlock(self, text):
+        # Comments
+        comment_pos = text.find("#")
+        if comment_pos >= 0:
+            self.setFormat(comment_pos, len(text) - comment_pos, self.comment)
+            code = text[:comment_pos]
+        else:
+            code = text
+
+        # Numbers
+        i = 0
+        while i < len(code):
+            if code[i].isdigit() or (
+                code[i] == "." and i + 1 < len(code) and code[i + 1].isdigit()
+            ):
+                start = i
+                i += 1
+                while i < len(code) and (code[i].isdigit() or code[i] == "."):
+                    i += 1
+                self.setFormat(start, i - start, self.number)
+            else:
+                i += 1
+
+        for char in "+-*/=():[];":
+            start = 0
+            while True:
+                pos = code.find(char, start)
+                if pos < 0:
+                    break
+                self.setFormat(pos, 1, self.operator)
+                start = pos + 1
+
+        # Function definitions: name before ':'
+        colon = code.find(":")
+        if colon > 0:
+            name = code[:colon].strip()
+            if name:
+                pos = code.find(name)
+                self.setFormat(pos, len(name), self.keyword)
+
+
+class LineNumberArea(QWidget):
+    def __init__(self, editor):
+        super().__init__(editor)
+        self.editor = editor
+
+    def sizeHint(self):
+        return QSize(self.editor.line_number_width(), 0)
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.fillRect(event.rect(), QColor("#0f151c"))
+
+        block = self.editor.firstVisibleBlock()
+        block_number = block.blockNumber()
+        top = int(
+            self.editor.blockBoundingGeometry(block).translated(
+                self.editor.contentOffset()
+            ).top()
+        )
+        bottom = top + int(self.editor.blockBoundingRect(block).height())
+
+        while block.isValid() and top <= event.rect().bottom():
+            if block.isVisible() and bottom >= event.rect().top():
+                painter.setPen(QColor("#596878"))
+                painter.drawText(
+                    0,
+                    top,
+                    self.width() - 7,
+                    self.editor.fontMetrics().height(),
+                    Qt.AlignRight,
+                    str(block_number + 1),
+                )
+
+            block = block.next()
+            top = bottom
+            bottom = top + int(self.editor.blockBoundingRect(block).height())
+            block_number += 1
+
+
+class CodeEditor(QPlainTextEdit):
+    def __init__(self):
+        super().__init__()
+
+        self.line_numbers = LineNumberArea(self)
+        self.blockCountChanged.connect(self.update_line_number_width)
+        self.updateRequest.connect(self.update_line_number_area)
+        self.cursorPositionChanged.connect(self.highlight_current_line)
+
+        self.update_line_number_width(0)
+        self.highlight_current_line()
+
+        font = QFont("JetBrains Mono", 11)
+        font.setStyleHint(QFont.Monospace)
+        self.setFont(font)
+        self.setTabStopDistance(
+            self.fontMetrics().horizontalAdvance(" ") * 4
+        )
+
+    def line_number_width(self):
+        digits = len(str(max(1, self.blockCount())))
+        return 12 + self.fontMetrics().horizontalAdvance("9") * digits
+
+    def update_line_number_width(self, _):
+        self.setViewportMargins(self.line_number_width(), 0, 0, 0)
+
+    def update_line_number_area(self, rect, dy):
+        if dy:
+            self.line_numbers.scroll(0, dy)
+        else:
+            self.line_numbers.update(0, rect.y(), self.line_numbers.width(), rect.height())
+
+        if rect.contains(self.viewport().rect()):
+            self.update_line_number_width(0)
+
+    def resizeEvent(self, event):
+        super().resizeEvent(event)
+        rect = self.contentsRect()
+        rect.setWidth(self.line_number_width())
+        self.line_numbers.setGeometry(rect)
+
+    def highlight_current_line(self):
+        extra = []
+        if not self.isReadOnly():
+            selection = QTextCharFormat()
+            selection.setBackground(QColor("#111a24"))
+            selection.setProperty(QTextCharFormat.FullWidthSelection, True)
+            extra.append((self.textCursor(), selection))
+        self.setExtraSelections(extra)
+
+
+class ResultGraph(QWidget):
+    """Small dependency-free graph of numeric results."""
+
+    def __init__(self):
+        super().__init__()
+        self.values = []
+
+    def set_values(self, values):
+        self.values = values[-50:]
+        self.update()
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.Antialiasing)
+        painter.fillRect(self.rect(), QColor("#0b0f14"))
+
+        r = self.rect().adjusted(45, 20, -20, -35)
+        painter.setPen(QColor("#273442"))
+        painter.drawRect(r)
+
+        if not self.values:
+            painter.setPen(QColor("#647383"))
+            painter.drawText(r, Qt.AlignCenter, "No numeric results yet")
+            return
+
+        numeric = [v for v in self.values if math.isfinite(v)]
+        if not numeric:
+            return
+
+        lo = min(numeric)
+        hi = max(numeric)
+        if abs(hi - lo) < 1e-12:
+            lo -= 1
+            hi += 1
+
+        painter.setPen(QColor("#344454"))
+        for frac in (0.0, 0.5, 1.0):
+            y = int(r.bottom() - frac * r.height())
+            painter.drawLine(r.left(), y, r.right(), y)
+
+        painter.setPen(QColor("#5f6f80"))
+        painter.drawText(5, r.top() + 5, 35, 20, Qt.AlignRight, f"{hi:g}")
+        painter.drawText(5, r.bottom() - 15, 35, 20, Qt.AlignRight, f"{lo:g}")
+
+        if len(numeric) == 1:
+            x = r.center().x()
+            y = r.bottom() - (numeric[0] - lo) / (hi - lo) * r.height()
+            painter.setBrush(QColor("#58a6ff"))
+            painter.drawEllipse(int(x - 4), int(y - 4), 8, 8)
+            return
+
+        points = []
+        count = len(numeric)
+        for i, value in enumerate(numeric):
+            x = r.left() + i * r.width() / max(1, count - 1)
+            y = r.bottom() - (value - lo) / (hi - lo) * r.height()
+            points.append((x, y))
+
+        painter.setPen(QColor("#58a6ff"))
+        for a, b in zip(points, points[1:]):
+            painter.drawLine(int(a[0]), int(a[1]), int(b[0]), int(b[1]))
+
+        painter.setBrush(QColor("#58a6ff"))
+        for x, y in points:
+            painter.drawEllipse(int(x - 3), int(y - 3), 6, 6)
+
+
+class AbacusIDE(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.core = AbacusCore()
+        self.step = 0
+        self.results = []
+
+        self.setWindowTitle("Abacus IDE")
+        self.resize(1400, 850)
+        self.setMinimumSize(1050, 650)
+
+        self._build_main()
+        self._build_toolbar()
+        self._build_docks()
+        self._build_statusbar()
+
+        self._refresh_sidebars()
+        self.editor.setFocus()
+
+    def _build_toolbar(self):
+        toolbar = QToolBar()
+        toolbar.setMovable(False)
+        toolbar.setToolButtonStyle(Qt.ToolButtonTextOnly)
+        self.addToolBar(toolbar)
+
+        run = toolbar.addAction("▶  Run")
+        run.triggered.connect(self.run_document)
+
+        run_line = toolbar.addAction("Run line")
+        run_line.triggered.connect(self.run_current_line)
+
+        toolbar.addSeparator()
+
+        for symbol in ("+", "-", "*", "/", "(", ")", "[", "]", "="):
+            button = QPushButton(symbol)
+            button.setObjectName("operator")
+            button.clicked.connect(
+                lambda checked=False, s=symbol: self.insert_operator(s)
+            )
+            toolbar.addWidget(button)
+
+        toolbar.addSeparator()
+
+        clear = toolbar.addAction("Clear")
+        clear.triggered.connect(self.editor.clear)
+
+        toolbar.addSeparator()
+
+        reset = toolbar.addAction("Reset")
+        reset.triggered.connect(self.reset_abacus)
+
+    def _build_main(self):
+        self.tabs = QTabWidget()
+        self.setCentralWidget(self.tabs)
+
+        # Workspace tab
+        workspace = QWidget()
+        workspace_layout = QVBoxLayout(workspace)
+        workspace_layout.setContentsMargins(10, 10, 10, 10)
+        workspace_layout.setSpacing(8)
+
+        editor_header = QHBoxLayout()
+        label = QLabel("Expression editor")
+        label.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+
+        hint = QLabel(
+            "One command per line  •  # comments  •  Enter = run line"
+        )
+        hint.setStyleSheet("color: #657585;")
+
+        editor_header.addWidget(label)
+        editor_header.addStretch()
+        editor_header.addWidget(hint)
+        workspace_layout.addLayout(editor_header)
+
+        self.editor = CodeEditor()
+        AbacusHighlighter(self.editor.document())
+        self.editor.setPlainText(
+            "# Example\n"
+            "alpha = 10\n"
+            "beta = 2\n"
+            "alpha + beta * 3\n"
+        )
+        workspace_layout.addWidget(self.editor, 1)
+
+        bottom = QFrame()
+        bottom.setObjectName("bottomCard")
+        bottom_layout = QHBoxLayout(bottom)
+        bottom_layout.setContentsMargins(10, 8, 10, 8)
+
+        bottom_layout.addWidget(QLabel("Quick input:"))
+
+        self.single_line = QLineEdit()
+        self.single_line.setObjectName("singleLine")
+        self.single_line.setPlaceholderText("Enter expression...")
+        self.single_line.returnPressed.connect(self.run_single_line)
+        bottom_layout.addWidget(self.single_line, 1)
+
+        execute = QPushButton("Execute")
+        execute.clicked.connect(self.run_single_line)
+        bottom_layout.addWidget(execute)
+
+        workspace_layout.addWidget(bottom)
+
+        self.tabs.addTab(workspace, "Workspace")
+
+        # Results tab
+        results_page = QWidget()
+        results_layout = QVBoxLayout(results_page)
+        results_layout.setContentsMargins(10, 10, 10, 10)
+
+        self.results_table = QTableWidget(0, 4)
+        self.results_table.setHorizontalHeaderLabels(
+            ["Step", "Expression", "Result", "Comment"]
+        )
+        self.results_table.horizontalHeader().setStretchLastSection(True)
+        self.results_table.setAlternatingRowColors(False)
+        results_layout.addWidget(self.results_table)
+
+        self.tabs.addTab(results_page, "Results")
+
+        # Graph tab
+        graph_page = QWidget()
+        graph_layout = QVBoxLayout(graph_page)
+        graph_layout.setContentsMargins(10, 10, 10, 10)
+
+        graph_title = QLabel("Numeric result history")
+        graph_title.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+        graph_layout.addWidget(graph_title)
+
+        self.graph = ResultGraph()
+        graph_layout.addWidget(self.graph, 1)
+
+        graph_info = QLabel(
+            "The graph uses numeric results from executed expressions."
+        )
+        graph_info.setStyleSheet("color: #657585;")
+        graph_layout.addWidget(graph_info)
+
+        self.tabs.addTab(graph_page, "Graph")
+
+    def _build_docks(self):
+        self.variables_dock = self._make_dock(
+            "Variables", self._make_list_widget()
+        )
+        self.functions_dock = self._make_dock(
+            "Functions", self._make_list_widget()
+        )
+        self.history_dock = self._make_dock(
+            "History", self._make_list_widget()
+        )
+
+        self.variables_list = self.variables_dock.widget()
+        self.functions_list = self.functions_dock.widget()
+        self.history_list = self.history_dock.widget()
+
+        self.addDockWidget(Qt.RightDockWidgetArea, self.variables_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.functions_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.history_dock)
+
+        self.tabifyDockWidget(self.variables_dock, self.functions_dock)
+        self.tabifyDockWidget(self.functions_dock, self.history_dock)
+        self.variables_dock.raise_()
+
+    def _make_list_widget(self):
+        return QListWidget()
+
+    def _make_dock(self, title, widget):
+        dock = QDockWidget(title, self)
+        dock.setAllowedAreas(
+            Qt.LeftDockWidgetArea | Qt.RightDockWidgetArea
+        )
+        dock.setFeatures(
+            QDockWidget.DockWidgetMovable
+            | QDockWidget.DockWidgetFloatable
+        )
+        dock.setWidget(widget)
+        return dock
+
+    def _build_statusbar(self):
+        self.status = QStatusBar()
+        self.setStatusBar(self.status)
+        self.status.showMessage("Ready")
+
+    def insert_operator(self, symbol):
+        self.editor.insertPlainText(symbol)
+        self.editor.setFocus()
+
+    def run_single_line(self):
+        text = self.single_line.text().strip()
+        if not text:
+            return
+
+        self._execute(text)
+        self.single_line.clear()
+
+    def run_current_line(self):
+        cursor = self.editor.textCursor()
+        cursor.select(cursor.LineUnderCursor)
+        line = cursor.selectedText().strip()
+
+        if line:
+            self._execute(line)
+
+    def run_document(self):
+        lines = self.editor.toPlainText().splitlines()
+
+        executed = 0
+        for line in lines:
+            line = line.strip()
+            if not line or line.startswith("#"):
+                continue
+
+            self._execute(line)
+            executed += 1
+
+        self.status.showMessage(f"Executed {executed} command(s)")
+
+    def _execute(self, text):
+        self.step += 1
+
+        try:
+            result = self.core.parse_input(text)
+        except Exception as exc:
+            self.step -= 1
+            self.status.showMessage(f"Error: {exc}")
+            self.history_list.addItem(f"ERROR  {text}  →  {exc}")
+            return
+
+        # Critical: assignments/functions return None, but their
+        # dictionaries are already changed. Refresh immediately.
+        self._refresh_sidebars()
+
+        if not result:
+            self.status.showMessage(f"Updated: {text}")
+            return
+
+        original, _, value, comment = result
+        value_text = str(value)
+        comment_text = comment or ""
+
+        self.results.append(
+            {
+                "step": self.step,
+                "expression": original,
+                "result": value_text,
+                "comment": comment_text,
+            }
+        )
+
+        self.history_list.addItem(
+            f"{self.step}.  {original}  =  {value_text}"
+        )
+        self.history_list.scrollToBottom()
+
+        self._add_result_row(
+            self.step, original, value_text, comment_text
+        )
+
+        try:
+            numeric = float(value)
+        except (TypeError, ValueError):
+            numeric = None
+
+        if numeric is not None and math.isfinite(numeric):
+            self.graph.values.append(numeric)
+            self.graph.set_values(self.graph.values)
+
+        self.status.showMessage(f"Result: {value_text}")
+
+    def _add_result_row(self, step, expression, result, comment):
+        row = self.results_table.rowCount()
+        self.results_table.insertRow(row)
+
+        values = [str(step), expression, result, comment]
+
+        for col, value in enumerate(values):
+            self.results_table.setItem(
+                row, col, QTableWidgetItem(value)
+            )
+
+        self.results_table.resizeColumnsToContents()
+        self.results_table.scrollToBottom()
+
+    def _refresh_sidebars(self):
+        self.variables_list.clear()
+
+        for key, value in self.core.get_vars().items():
+            self.variables_list.addItem(f"{key}    =    {value}")
+
+        self.functions_list.clear()
+
+        for key, value in self.core.get_funcs().items():
+            self.functions_list.addItem(f"{key}    =    {value}")
+
+    def reset_abacus(self):
+        self.core = AbacusCore()
+        self.step = 0
+        self.results.clear()
+
+        self.variables_list.clear()
+        self.functions_list.clear()
+        self.history_list.clear()
+        self.results_table.setRowCount(0)
+
+        self.graph.set_values([])
+        self.status.showMessage("Abacus state reset")
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+    app.setStyleSheet(STYLE)
+
+    window = AbacusIDE()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/abacus_ide_fixed_v2.py b/abacus_ide_fixed_v2.py
new file mode 100644
index 0000000..8a29f68
--- /dev/null
+++ b/abacus_ide_fixed_v2.py
@@ -0,0 +1,764 @@
+import math
+import sys
+
+from PySide6.QtCore import Qt, QRect, QSize
+from PySide6.QtGui import (
+    QColor,
+    QFont,
+    QPainter,
+    QSyntaxHighlighter,
+    QTextCharFormat,
+)
+from PySide6.QtWidgets import (
+    QApplication,
+    QDockWidget,
+    QFrame,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListWidget,
+    QMainWindow,
+    QPlainTextEdit,
+    QPushButton,
+    QSplitter,
+    QStatusBar,
+    QTabWidget,
+    QTableWidget,
+    QTableWidgetItem,
+    QToolBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+from abacus_core import AbacusCore
+
+
+STYLE = """
+QMainWindow, QWidget {
+    background: #0d1117;
+    color: #e6edf3;
+    font-family: "Segoe UI";
+    font-size: 13px;
+}
+
+QToolBar {
+    background: #111820;
+    border: 0;
+    border-bottom: 1px solid #202a36;
+    spacing: 5px;
+    padding: 6px 8px;
+}
+
+QToolButton {
+    color: #c9d1d9;
+    background: transparent;
+    border-radius: 7px;
+    padding: 7px 10px;
+}
+
+QToolButton:hover {
+    background: #1b2531;
+    color: #ffffff;
+}
+
+QTabWidget::pane {
+    border: 1px solid #202a36;
+    background: #0d1117;
+}
+
+QTabBar::tab {
+    background: #111820;
+    color: #7d8b99;
+    border: 1px solid #202a36;
+    border-bottom: none;
+    padding: 9px 16px;
+    margin-right: 2px;
+}
+
+QTabBar::tab:selected {
+    background: #17212c;
+    color: #f0f6fc;
+}
+
+QDockWidget {
+    color: #aeb9c6;
+    titlebar-close-icon: none;
+    titlebar-normal-icon: none;
+}
+
+QDockWidget::title {
+    background: #111820;
+    border-bottom: 1px solid #202a36;
+    padding: 9px 11px;
+    font-weight: 700;
+}
+
+QFrame#editorCard, QFrame#bottomCard {
+    background: #111820;
+    border: 1px solid #202a36;
+    border-radius: 10px;
+}
+
+QPlainTextEdit {
+    background: #0b0f14;
+    color: #d6deea;
+    border: 1px solid #202a36;
+    border-radius: 9px;
+    selection-background-color: #244a7d;
+    padding: 8px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+    font-size: 14px;
+}
+
+QLineEdit#singleLine {
+    background: #0b0f14;
+    color: #f0f6fc;
+    border: 1px solid #303b48;
+    border-radius: 9px;
+    padding: 9px 11px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+}
+
+QLineEdit#singleLine:focus {
+    border: 1px solid #3b82f6;
+}
+
+QPushButton {
+    background: #2563eb;
+    color: white;
+    border: none;
+    border-radius: 8px;
+    padding: 8px 13px;
+    font-weight: 700;
+}
+
+QPushButton:hover {
+    background: #3475ef;
+}
+
+QPushButton#operator {
+    background: #1b2531;
+    color: #cbd5e1;
+    border: 1px solid #293543;
+    min-width: 34px;
+}
+
+QPushButton#operator:hover {
+    background: #253344;
+    color: #ffffff;
+}
+
+QPushButton#secondary {
+    background: #1b2531;
+    color: #b9c4d0;
+    border: 1px solid #293543;
+}
+
+QListWidget, QTableWidget {
+    background: #0d131a;
+    color: #cbd5e1;
+    border: 1px solid #202a36;
+    border-radius: 8px;
+    outline: none;
+}
+
+QListWidget::item {
+    padding: 7px 8px;
+    border-radius: 6px;
+}
+
+QListWidget::item:hover {
+    background: #17212c;
+}
+
+QListWidget::item:selected {
+    background: #1c3153;
+    color: #ffffff;
+}
+
+QHeaderView::section {
+    background: #161f29;
+    color: #9aa8b7;
+    border: none;
+    border-right: 1px solid #202a36;
+    border-bottom: 1px solid #202a36;
+    padding: 7px;
+}
+
+QTableWidget::item {
+    padding: 6px;
+    border-bottom: 1px solid #18212b;
+}
+
+QStatusBar {
+    background: #0b0f14;
+    color: #7d8b99;
+    border-top: 1px solid #202a36;
+}
+
+QScrollBar:vertical {
+    background: #0d131a;
+    width: 9px;
+}
+
+QScrollBar::handle:vertical {
+    background: #303c4a;
+    border-radius: 4px;
+    min-height: 25px;
+}
+
+QScrollBar::add-line:vertical,
+QScrollBar::sub-line:vertical {
+    height: 0;
+}
+"""
+
+
+class AbacusHighlighter(QSyntaxHighlighter):
+    def __init__(self, document):
+        super().__init__(document)
+
+        self.number = QTextCharFormat()
+        self.number.setForeground(QColor("#79c0ff"))
+
+        self.operator = QTextCharFormat()
+        self.operator.setForeground(QColor("#ff7b72"))
+
+        self.comment = QTextCharFormat()
+        self.comment.setForeground(QColor("#6e7681"))
+        self.comment.setFontItalic(True)
+
+        self.assignment = QTextCharFormat()
+        self.assignment.setForeground(QColor("#d2a8ff"))
+
+        self.keyword = QTextCharFormat()
+        self.keyword.setForeground(QColor("#ffa657"))
+
+    def highlightBlock(self, text):
+        # Comments
+        comment_pos = text.find("#")
+        if comment_pos >= 0:
+            self.setFormat(comment_pos, len(text) - comment_pos, self.comment)
+            code = text[:comment_pos]
+        else:
+            code = text
+
+        # Numbers
+        i = 0
+        while i < len(code):
+            if code[i].isdigit() or (
+                code[i] == "." and i + 1 < len(code) and code[i + 1].isdigit()
+            ):
+                start = i
+                i += 1
+                while i < len(code) and (code[i].isdigit() or code[i] == "."):
+                    i += 1
+                self.setFormat(start, i - start, self.number)
+            else:
+                i += 1
+
+        for char in "+-*/=():[];":
+            start = 0
+            while True:
+                pos = code.find(char, start)
+                if pos < 0:
+                    break
+                self.setFormat(pos, 1, self.operator)
+                start = pos + 1
+
+        # Function definitions: name before ':'
+        colon = code.find(":")
+        if colon > 0:
+            name = code[:colon].strip()
+            if name:
+                pos = code.find(name)
+                self.setFormat(pos, len(name), self.keyword)
+
+
+class LineNumberArea(QWidget):
+    def __init__(self, editor):
+        super().__init__(editor)
+        self.editor = editor
+
+    def sizeHint(self):
+        return QSize(self.editor.line_number_width(), 0)
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.fillRect(event.rect(), QColor("#0f151c"))
+
+        block = self.editor.firstVisibleBlock()
+        block_number = block.blockNumber()
+        top = int(
+            self.editor.blockBoundingGeometry(block).translated(
+                self.editor.contentOffset()
+            ).top()
+        )
+        bottom = top + int(self.editor.blockBoundingRect(block).height())
+
+        while block.isValid() and top <= event.rect().bottom():
+            if block.isVisible() and bottom >= event.rect().top():
+                painter.setPen(QColor("#596878"))
+                painter.drawText(
+                    0,
+                    top,
+                    self.width() - 7,
+                    self.editor.fontMetrics().height(),
+                    Qt.AlignRight,
+                    str(block_number + 1),
+                )
+
+            block = block.next()
+            top = bottom
+            bottom = top + int(self.editor.blockBoundingRect(block).height())
+            block_number += 1
+
+
+class CodeEditor(QPlainTextEdit):
+    def __init__(self):
+        super().__init__()
+
+        self.line_numbers = LineNumberArea(self)
+        self.blockCountChanged.connect(self.update_line_number_width)
+        self.updateRequest.connect(self.update_line_number_area)
+        self.cursorPositionChanged.connect(self.highlight_current_line)
+
+        self.update_line_number_width(0)
+        self.highlight_current_line()
+
+        font = QFont("JetBrains Mono", 11)
+        font.setStyleHint(QFont.Monospace)
+        self.setFont(font)
+        self.setTabStopDistance(
+            self.fontMetrics().horizontalAdvance(" ") * 4
+        )
+
+    def line_number_width(self):
+        digits = len(str(max(1, self.blockCount())))
+        return 12 + self.fontMetrics().horizontalAdvance("9") * digits
+
+    def update_line_number_width(self, _):
+        self.setViewportMargins(self.line_number_width(), 0, 0, 0)
+
+    def update_line_number_area(self, rect, dy):
+        if dy:
+            self.line_numbers.scroll(0, dy)
+        else:
+            self.line_numbers.update(0, rect.y(), self.line_numbers.width(), rect.height())
+
+        if rect.contains(self.viewport().rect()):
+            self.update_line_number_width(0)
+
+    def resizeEvent(self, event):
+        super().resizeEvent(event)
+        rect = self.contentsRect()
+        rect.setWidth(self.line_number_width())
+        self.line_numbers.setGeometry(rect)
+
+    def highlight_current_line(self):
+        extra = []
+        if not self.isReadOnly():
+            selection = QTextCharFormat()
+            selection.setBackground(QColor("#111a24"))
+            selection.setProperty(QTextCharFormat.FullWidthSelection, True)
+            extra_selection = self.ExtraSelection()
+            extra_selection.cursor = self.textCursor()
+            extra_selection.format = selection
+            extra.append(extra_selection)
+        self.setExtraSelections(extra)
+
+
+class ResultGraph(QWidget):
+    """Small dependency-free graph of numeric results."""
+
+    def __init__(self):
+        super().__init__()
+        self.values = []
+
+    def set_values(self, values):
+        self.values = values[-50:]
+        self.update()
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.Antialiasing)
+        painter.fillRect(self.rect(), QColor("#0b0f14"))
+
+        r = self.rect().adjusted(45, 20, -20, -35)
+        painter.setPen(QColor("#273442"))
+        painter.drawRect(r)
+
+        if not self.values:
+            painter.setPen(QColor("#647383"))
+            painter.drawText(r, Qt.AlignCenter, "No numeric results yet")
+            return
+
+        numeric = [v for v in self.values if math.isfinite(v)]
+        if not numeric:
+            return
+
+        lo = min(numeric)
+        hi = max(numeric)
+        if abs(hi - lo) < 1e-12:
+            lo -= 1
+            hi += 1
+
+        painter.setPen(QColor("#344454"))
+        for frac in (0.0, 0.5, 1.0):
+            y = int(r.bottom() - frac * r.height())
+            painter.drawLine(r.left(), y, r.right(), y)
+
+        painter.setPen(QColor("#5f6f80"))
+        painter.drawText(5, r.top() + 5, 35, 20, Qt.AlignRight, f"{hi:g}")
+        painter.drawText(5, r.bottom() - 15, 35, 20, Qt.AlignRight, f"{lo:g}")
+
+        if len(numeric) == 1:
+            x = r.center().x()
+            y = r.bottom() - (numeric[0] - lo) / (hi - lo) * r.height()
+            painter.setBrush(QColor("#58a6ff"))
+            painter.drawEllipse(int(x - 4), int(y - 4), 8, 8)
+            return
+
+        points = []
+        count = len(numeric)
+        for i, value in enumerate(numeric):
+            x = r.left() + i * r.width() / max(1, count - 1)
+            y = r.bottom() - (value - lo) / (hi - lo) * r.height()
+            points.append((x, y))
+
+        painter.setPen(QColor("#58a6ff"))
+        for a, b in zip(points, points[1:]):
+            painter.drawLine(int(a[0]), int(a[1]), int(b[0]), int(b[1]))
+
+        painter.setBrush(QColor("#58a6ff"))
+        for x, y in points:
+            painter.drawEllipse(int(x - 3), int(y - 3), 6, 6)
+
+
+class AbacusIDE(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.core = AbacusCore()
+        self.step = 0
+        self.results = []
+
+        self.setWindowTitle("Abacus IDE")
+        self.resize(1400, 850)
+        self.setMinimumSize(1050, 650)
+
+        self._build_main()
+        self._build_toolbar()
+        self._build_docks()
+        self._build_statusbar()
+
+        self._refresh_sidebars()
+        self.editor.setFocus()
+
+    def _build_toolbar(self):
+        toolbar = QToolBar()
+        toolbar.setMovable(False)
+        toolbar.setToolButtonStyle(Qt.ToolButtonTextOnly)
+        self.addToolBar(toolbar)
+
+        run = toolbar.addAction("▶  Run")
+        run.triggered.connect(self.run_document)
+
+        run_line = toolbar.addAction("Run line")
+        run_line.triggered.connect(self.run_current_line)
+
+        toolbar.addSeparator()
+
+        for symbol in ("+", "-", "*", "/", "(", ")", "[", "]", "="):
+            button = QPushButton(symbol)
+            button.setObjectName("operator")
+            button.clicked.connect(
+                lambda checked=False, s=symbol: self.insert_operator(s)
+            )
+            toolbar.addWidget(button)
+
+        toolbar.addSeparator()
+
+        clear = toolbar.addAction("Clear")
+        clear.triggered.connect(self.editor.clear)
+
+        toolbar.addSeparator()
+
+        reset = toolbar.addAction("Reset")
+        reset.triggered.connect(self.reset_abacus)
+
+    def _build_main(self):
+        self.tabs = QTabWidget()
+        self.setCentralWidget(self.tabs)
+
+        # Workspace tab
+        workspace = QWidget()
+        workspace_layout = QVBoxLayout(workspace)
+        workspace_layout.setContentsMargins(10, 10, 10, 10)
+        workspace_layout.setSpacing(8)
+
+        editor_header = QHBoxLayout()
+        label = QLabel("Expression editor")
+        label.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+
+        hint = QLabel(
+            "One command per line  •  # comments  •  Enter = run line"
+        )
+        hint.setStyleSheet("color: #657585;")
+
+        editor_header.addWidget(label)
+        editor_header.addStretch()
+        editor_header.addWidget(hint)
+        workspace_layout.addLayout(editor_header)
+
+        self.editor = CodeEditor()
+        AbacusHighlighter(self.editor.document())
+        self.editor.setPlainText(
+            "# Example\n"
+            "alpha = 10\n"
+            "beta = 2\n"
+            "alpha + beta * 3\n"
+        )
+        workspace_layout.addWidget(self.editor, 1)
+
+        bottom = QFrame()
+        bottom.setObjectName("bottomCard")
+        bottom_layout = QHBoxLayout(bottom)
+        bottom_layout.setContentsMargins(10, 8, 10, 8)
+
+        bottom_layout.addWidget(QLabel("Quick input:"))
+
+        self.single_line = QLineEdit()
+        self.single_line.setObjectName("singleLine")
+        self.single_line.setPlaceholderText("Enter expression...")
+        self.single_line.returnPressed.connect(self.run_single_line)
+        bottom_layout.addWidget(self.single_line, 1)
+
+        execute = QPushButton("Execute")
+        execute.clicked.connect(self.run_single_line)
+        bottom_layout.addWidget(execute)
+
+        workspace_layout.addWidget(bottom)
+
+        self.tabs.addTab(workspace, "Workspace")
+
+        # Results tab
+        results_page = QWidget()
+        results_layout = QVBoxLayout(results_page)
+        results_layout.setContentsMargins(10, 10, 10, 10)
+
+        self.results_table = QTableWidget(0, 4)
+        self.results_table.setHorizontalHeaderLabels(
+            ["Step", "Expression", "Result", "Comment"]
+        )
+        self.results_table.horizontalHeader().setStretchLastSection(True)
+        self.results_table.setAlternatingRowColors(False)
+        results_layout.addWidget(self.results_table)
+
+        self.tabs.addTab(results_page, "Results")
+
+        # Graph tab
+        graph_page = QWidget()
+        graph_layout = QVBoxLayout(graph_page)
+        graph_layout.setContentsMargins(10, 10, 10, 10)
+
+        graph_title = QLabel("Numeric result history")
+        graph_title.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+        graph_layout.addWidget(graph_title)
+
+        self.graph = ResultGraph()
+        graph_layout.addWidget(self.graph, 1)
+
+        graph_info = QLabel(
+            "The graph uses numeric results from executed expressions."
+        )
+        graph_info.setStyleSheet("color: #657585;")
+        graph_layout.addWidget(graph_info)
+
+        self.tabs.addTab(graph_page, "Graph")
+
+    def _build_docks(self):
+        self.variables_dock = self._make_dock(
+            "Variables", self._make_list_widget()
+        )
+        self.functions_dock = self._make_dock(
+            "Functions", self._make_list_widget()
+        )
+        self.history_dock = self._make_dock(
+            "History", self._make_list_widget()
+        )
+
+        self.variables_list = self.variables_dock.widget()
+        self.functions_list = self.functions_dock.widget()
+        self.history_list = self.history_dock.widget()
+
+        self.addDockWidget(Qt.RightDockWidgetArea, self.variables_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.functions_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.history_dock)
+
+        self.tabifyDockWidget(self.variables_dock, self.functions_dock)
+        self.tabifyDockWidget(self.functions_dock, self.history_dock)
+        self.variables_dock.raise_()
+
+    def _make_list_widget(self):
+        return QListWidget()
+
+    def _make_dock(self, title, widget):
+        dock = QDockWidget(title, self)
+        dock.setAllowedAreas(
+            Qt.LeftDockWidgetArea | Qt.RightDockWidgetArea
+        )
+        dock.setFeatures(
+            QDockWidget.DockWidgetMovable
+            | QDockWidget.DockWidgetFloatable
+        )
+        dock.setWidget(widget)
+        return dock
+
+    def _build_statusbar(self):
+        self.status = QStatusBar()
+        self.setStatusBar(self.status)
+        self.status.showMessage("Ready")
+
+    def insert_operator(self, symbol):
+        self.editor.insertPlainText(symbol)
+        self.editor.setFocus()
+
+    def run_single_line(self):
+        text = self.single_line.text().strip()
+        if not text:
+            return
+
+        self._execute(text)
+        self.single_line.clear()
+
+    def run_current_line(self):
+        cursor = self.editor.textCursor()
+        cursor.select(cursor.LineUnderCursor)
+        line = cursor.selectedText().strip()
+
+        if line:
+            self._execute(line)
+
+    def run_document(self):
+        lines = self.editor.toPlainText().splitlines()
+
+        executed = 0
+        for line in lines:
+            line = line.strip()
+            if not line or line.startswith("#"):
+                continue
+
+            self._execute(line)
+            executed += 1
+
+        self.status.showMessage(f"Executed {executed} command(s)")
+
+    def _execute(self, text):
+        self.step += 1
+
+        try:
+            result = self.core.parse_input(text)
+        except Exception as exc:
+            self.step -= 1
+            self.status.showMessage(f"Error: {exc}")
+            self.history_list.addItem(f"ERROR  {text}  →  {exc}")
+            return
+
+        # Critical: assignments/functions return None, but their
+        # dictionaries are already changed. Refresh immediately.
+        self._refresh_sidebars()
+
+        if not result:
+            self.status.showMessage(f"Updated: {text}")
+            return
+
+        original, _, value, comment = result
+        value_text = str(value)
+        comment_text = comment or ""
+
+        self.results.append(
+            {
+                "step": self.step,
+                "expression": original,
+                "result": value_text,
+                "comment": comment_text,
+            }
+        )
+
+        self.history_list.addItem(
+            f"{self.step}.  {original}  =  {value_text}"
+        )
+        self.history_list.scrollToBottom()
+
+        self._add_result_row(
+            self.step, original, value_text, comment_text
+        )
+
+        try:
+            numeric = float(value)
+        except (TypeError, ValueError):
+            numeric = None
+
+        if numeric is not None and math.isfinite(numeric):
+            self.graph.values.append(numeric)
+            self.graph.set_values(self.graph.values)
+
+        self.status.showMessage(f"Result: {value_text}")
+
+    def _add_result_row(self, step, expression, result, comment):
+        row = self.results_table.rowCount()
+        self.results_table.insertRow(row)
+
+        values = [str(step), expression, result, comment]
+
+        for col, value in enumerate(values):
+            self.results_table.setItem(
+                row, col, QTableWidgetItem(value)
+            )
+
+        self.results_table.resizeColumnsToContents()
+        self.results_table.scrollToBottom()
+
+    def _refresh_sidebars(self):
+        self.variables_list.clear()
+
+        for key, value in self.core.get_vars().items():
+            self.variables_list.addItem(f"{key}    =    {value}")
+
+        self.functions_list.clear()
+
+        for key, value in self.core.get_funcs().items():
+            self.functions_list.addItem(f"{key}    =    {value}")
+
+    def reset_abacus(self):
+        self.core = AbacusCore()
+        self.step = 0
+        self.results.clear()
+
+        self.variables_list.clear()
+        self.functions_list.clear()
+        self.history_list.clear()
+        self.results_table.setRowCount(0)
+
+        self.graph.set_values([])
+        self.status.showMessage("Abacus state reset")
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+    app.setStyleSheet(STYLE)
+
+    window = AbacusIDE()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/abacus_ide_json_autocomplete.py b/abacus_ide_json_autocomplete.py
new file mode 100644
index 0000000..9b2311e
--- /dev/null
+++ b/abacus_ide_json_autocomplete.py
@@ -0,0 +1,1057 @@
+import json
+import math
+import sys
+
+from PySide6.QtCore import Qt, QSize, QStringListModel
+from PySide6.QtGui import (
+    QColor,
+    QFont,
+    QPainter,
+    QSyntaxHighlighter,
+    QTextCharFormat,
+)
+from PySide6.QtWidgets import (
+    QApplication,
+    QDockWidget,
+    QFrame,
+    QCompleter,
+    QFileDialog,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListWidget,
+    QMainWindow,
+    QPlainTextEdit,
+    QTextEdit,
+    QTextCursor,
+    QPushButton,
+    QStatusBar,
+    QTabWidget,
+    QTableWidget,
+    QTableWidgetItem,
+    QToolBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+from abacus_core import AbacusCore
+
+
+STYLE = """
+QMainWindow, QWidget {
+    background: #0d1117;
+    color: #e6edf3;
+    font-family: "Segoe UI";
+    font-size: 13px;
+}
+
+QToolBar {
+    background: #111820;
+    border: 0;
+    border-bottom: 1px solid #202a36;
+    spacing: 5px;
+    padding: 6px 8px;
+}
+
+QToolButton {
+    color: #c9d1d9;
+    background: transparent;
+    border-radius: 7px;
+    padding: 7px 10px;
+}
+
+QToolButton:hover {
+    background: #1b2531;
+    color: #ffffff;
+}
+
+QTabWidget::pane {
+    border: 1px solid #202a36;
+    background: #0d1117;
+}
+
+QTabBar::tab {
+    background: #111820;
+    color: #7d8b99;
+    border: 1px solid #202a36;
+    border-bottom: none;
+    padding: 9px 16px;
+    margin-right: 2px;
+}
+
+QTabBar::tab:selected {
+    background: #17212c;
+    color: #f0f6fc;
+}
+
+QDockWidget {
+    color: #aeb9c6;
+    titlebar-close-icon: none;
+    titlebar-normal-icon: none;
+}
+
+QDockWidget::title {
+    background: #111820;
+    border-bottom: 1px solid #202a36;
+    padding: 9px 11px;
+    font-weight: 700;
+}
+
+QFrame#editorCard, QFrame#bottomCard {
+    background: #111820;
+    border: 1px solid #202a36;
+    border-radius: 10px;
+}
+
+QPlainTextEdit {
+    background: #0b0f14;
+    color: #d6deea;
+    border: 1px solid #202a36;
+    border-radius: 9px;
+    selection-background-color: #244a7d;
+    padding: 8px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+    font-size: 14px;
+}
+
+QLineEdit#singleLine {
+    background: #0b0f14;
+    color: #f0f6fc;
+    border: 1px solid #303b48;
+    border-radius: 9px;
+    padding: 9px 11px;
+    font-family: "JetBrains Mono", "Consolas", monospace;
+}
+
+QLineEdit#singleLine:focus {
+    border: 1px solid #3b82f6;
+}
+
+QPushButton {
+    background: #2563eb;
+    color: white;
+    border: none;
+    border-radius: 8px;
+    padding: 8px 13px;
+    font-weight: 700;
+}
+
+QPushButton:hover {
+    background: #3475ef;
+}
+
+QPushButton#operator {
+    background: #1b2531;
+    color: #cbd5e1;
+    border: 1px solid #293543;
+    min-width: 34px;
+}
+
+QPushButton#operator:hover {
+    background: #253344;
+    color: #ffffff;
+}
+
+QPushButton#secondary {
+    background: #1b2531;
+    color: #b9c4d0;
+    border: 1px solid #293543;
+}
+
+QListWidget, QTableWidget {
+    background: #0d131a;
+    color: #cbd5e1;
+    border: 1px solid #202a36;
+    border-radius: 8px;
+    outline: none;
+}
+
+QListWidget::item {
+    padding: 7px 8px;
+    border-radius: 6px;
+}
+
+QListWidget::item:hover {
+    background: #17212c;
+}
+
+QListWidget::item:selected {
+    background: #1c3153;
+    color: #ffffff;
+}
+
+QHeaderView::section {
+    background: #161f29;
+    color: #9aa8b7;
+    border: none;
+    border-right: 1px solid #202a36;
+    border-bottom: 1px solid #202a36;
+    padding: 7px;
+}
+
+QTableWidget::item {
+    padding: 6px;
+    border-bottom: 1px solid #18212b;
+}
+
+QStatusBar {
+    background: #0b0f14;
+    color: #7d8b99;
+    border-top: 1px solid #202a36;
+}
+
+QScrollBar:vertical {
+    background: #0d131a;
+    width: 9px;
+}
+
+QScrollBar::handle:vertical {
+    background: #303c4a;
+    border-radius: 4px;
+    min-height: 25px;
+}
+
+QScrollBar::add-line:vertical,
+QScrollBar::sub-line:vertical {
+    height: 0;
+}
+"""
+
+
+class AbacusHighlighter(QSyntaxHighlighter):
+    def __init__(self, document):
+        super().__init__(document)
+
+        self.number = QTextCharFormat()
+        self.number.setForeground(QColor("#79c0ff"))
+
+        self.operator = QTextCharFormat()
+        self.operator.setForeground(QColor("#ff7b72"))
+
+        self.comment = QTextCharFormat()
+        self.comment.setForeground(QColor("#6e7681"))
+        self.comment.setFontItalic(True)
+
+        self.assignment = QTextCharFormat()
+        self.assignment.setForeground(QColor("#d2a8ff"))
+
+        self.keyword = QTextCharFormat()
+        self.keyword.setForeground(QColor("#ffa657"))
+
+    def highlightBlock(self, text):
+        # Comments
+        comment_pos = text.find("#")
+        if comment_pos >= 0:
+            self.setFormat(comment_pos, len(text) - comment_pos, self.comment)
+            code = text[:comment_pos]
+        else:
+            code = text
+
+        # Numbers
+        i = 0
+        while i < len(code):
+            if code[i].isdigit() or (
+                code[i] == "." and i + 1 < len(code) and code[i + 1].isdigit()
+            ):
+                start = i
+                i += 1
+                while i < len(code) and (code[i].isdigit() or code[i] == "."):
+                    i += 1
+                self.setFormat(start, i - start, self.number)
+            else:
+                i += 1
+
+        for char in "+-*/=():[];":
+            start = 0
+            while True:
+                pos = code.find(char, start)
+                if pos < 0:
+                    break
+                self.setFormat(pos, 1, self.operator)
+                start = pos + 1
+
+        # Function definitions: name before ':'
+        colon = code.find(":")
+        if colon > 0:
+            name = code[:colon].strip()
+            if name:
+                pos = code.find(name)
+                self.setFormat(pos, len(name), self.keyword)
+
+
+class LineNumberArea(QWidget):
+    def __init__(self, editor):
+        super().__init__(editor)
+        self.editor = editor
+
+    def sizeHint(self):
+        return QSize(self.editor.line_number_width(), 0)
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.fillRect(event.rect(), QColor("#0f151c"))
+
+        block = self.editor.firstVisibleBlock()
+        block_number = block.blockNumber()
+        top = int(
+            self.editor.blockBoundingGeometry(block).translated(
+                self.editor.contentOffset()
+            ).top()
+        )
+        bottom = top + int(self.editor.blockBoundingRect(block).height())
+
+        while block.isValid() and top <= event.rect().bottom():
+            if block.isVisible() and bottom >= event.rect().top():
+                painter.setPen(QColor("#596878"))
+                painter.drawText(
+                    0,
+                    top,
+                    self.width() - 7,
+                    self.editor.fontMetrics().height(),
+                    Qt.AlignRight,
+                    str(block_number + 1),
+                )
+
+            block = block.next()
+            top = bottom
+            bottom = top + int(self.editor.blockBoundingRect(block).height())
+            block_number += 1
+
+
+class CodeEditor(QPlainTextEdit):
+    def __init__(self):
+        super().__init__()
+
+        self.line_numbers = LineNumberArea(self)
+        self.error_lines = {}
+        self.completer = None
+
+        self.blockCountChanged.connect(self.update_line_number_width)
+        self.updateRequest.connect(self.update_line_number_area)
+        self.cursorPositionChanged.connect(self.highlight_current_line)
+
+        self.update_line_number_width(0)
+        self.highlight_current_line()
+
+        font = QFont("JetBrains Mono", 11)
+        font.setStyleHint(QFont.Monospace)
+        self.setFont(font)
+        self.setTabStopDistance(
+            self.fontMetrics().horizontalAdvance(" ") * 4
+        )
+
+    def line_number_width(self):
+        digits = len(str(max(1, self.blockCount())))
+        return 12 + self.fontMetrics().horizontalAdvance("9") * digits
+
+    def update_line_number_width(self, _):
+        self.setViewportMargins(self.line_number_width(), 0, 0, 0)
+
+    def update_line_number_area(self, rect, dy):
+        if dy:
+            self.line_numbers.scroll(0, dy)
+        else:
+            self.line_numbers.update(
+                0,
+                rect.y(),
+                self.line_numbers.width(),
+                rect.height(),
+            )
+
+        if rect.contains(self.viewport().rect()):
+            self.update_line_number_width(0)
+
+    def resizeEvent(self, event):
+        super().resizeEvent(event)
+        rect = self.contentsRect()
+        rect.setWidth(self.line_number_width())
+        self.line_numbers.setGeometry(rect)
+
+    def highlight_current_line(self):
+        extra = []
+
+        if not self.isReadOnly():
+            selection = QTextCharFormat()
+            selection.setBackground(QColor("#111a24"))
+            selection.setProperty(
+                QTextCharFormat.FullWidthSelection,
+                True,
+            )
+
+            extra_selection = QTextEdit.ExtraSelection()
+            extra_selection.cursor = self.textCursor()
+            extra_selection.format = selection
+            extra.append(extra_selection)
+
+        # Error lines always get a stronger red background.
+        for line_number, message in self.error_lines.items():
+            block = self.document().findBlockByNumber(line_number - 1)
+            if not block.isValid():
+                continue
+
+            cursor = self.textCursor()
+            cursor.setPosition(block.position())
+            cursor.setPosition(
+                block.position() + max(1, block.length() - 1),
+                QTextCursor.KeepAnchor,
+            )
+
+            selection = QTextCharFormat()
+            selection.setBackground(QColor("#4a1f25"))
+            selection.setForeground(QColor("#ffb4b4"))
+            selection.setProperty(
+                QTextCharFormat.FullWidthSelection,
+                True,
+            )
+
+            extra_selection = QTextEdit.ExtraSelection()
+            extra_selection.cursor = cursor
+            extra_selection.format = selection
+            extra.append(extra_selection)
+
+        self.setExtraSelections(extra)
+
+        self.line_numbers.update()
+
+    def set_error_lines(self, errors):
+        self.error_lines = dict(errors)
+        self.highlight_current_line()
+
+    def clear_error_lines(self):
+        self.error_lines.clear()
+        self.highlight_current_line()
+
+    def set_completer(self, completer):
+        self.completer = completer
+        completer.setWidget(self)
+        completer.setCompletionMode(QCompleter.PopupCompletion)
+        completer.setCaseSensitivity(Qt.CaseInsensitive)
+        completer.activated.connect(self.insert_completion)
+
+    def insert_completion(self, completion):
+        cursor = self.textCursor()
+        extra = len(completion) - len(self.completion_prefix())
+        if extra > 0:
+            cursor.insertText(completion[-extra:])
+        self.setTextCursor(cursor)
+
+    def completion_prefix(self):
+        cursor = self.textCursor()
+        text = cursor.block().text()
+        pos = cursor.positionInBlock()
+
+        start = pos
+        while start > 0:
+            char = text[start - 1]
+            if not (char.isalnum() or char == "_"):
+                break
+            start -= 1
+
+        return text[start:pos]
+
+    def show_completion(self):
+        if not self.completer:
+            return
+
+        prefix = self.completion_prefix()
+        if not prefix:
+            self.completer.popup().hide()
+            return
+
+        self.completer.setCompletionPrefix(prefix)
+
+        if self.completer.completionCount() == 0:
+            self.completer.popup().hide()
+            return
+
+        rect = self.cursorRect()
+        rect.setWidth(
+            self.completer.popup().sizeHintForColumn(0)
+            + self.completer.popup().verticalScrollBar().sizeHint().width()
+        )
+        self.completer.complete(rect)
+
+    def keyPressEvent(self, event):
+        if self.completer and self.completer.popup().isVisible():
+            if event.key() in (
+                Qt.Key_Enter,
+                Qt.Key_Return,
+                Qt.Key_Tab,
+                Qt.Key_Backtab,
+            ):
+                event.ignore()
+                return
+
+            if event.key() == Qt.Key_Escape:
+                self.completer.popup().hide()
+                return
+
+        if (
+            event.key() == Qt.Key_Space
+            and event.modifiers() & Qt.ControlModifier
+        ):
+            self.show_completion()
+            return
+
+        super().keyPressEvent(event)
+
+        if self.completer:
+            self.show_completion()
+
+class ResultGraph(QWidget):
+    """Small dependency-free graph of numeric results."""
+
+    def __init__(self):
+        super().__init__()
+        self.values = []
+
+    def set_values(self, values):
+        self.values = values[-50:]
+        self.update()
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.Antialiasing)
+        painter.fillRect(self.rect(), QColor("#0b0f14"))
+
+        r = self.rect().adjusted(45, 20, -20, -35)
+        painter.setPen(QColor("#273442"))
+        painter.drawRect(r)
+
+        if not self.values:
+            painter.setPen(QColor("#647383"))
+            painter.drawText(r, Qt.AlignCenter, "No numeric results yet")
+            return
+
+        numeric = [v for v in self.values if math.isfinite(v)]
+        if not numeric:
+            return
+
+        lo = min(numeric)
+        hi = max(numeric)
+        if abs(hi - lo) < 1e-12:
+            lo -= 1
+            hi += 1
+
+        painter.setPen(QColor("#344454"))
+        for frac in (0.0, 0.5, 1.0):
+            y = int(r.bottom() - frac * r.height())
+            painter.drawLine(r.left(), y, r.right(), y)
+
+        painter.setPen(QColor("#5f6f80"))
+        painter.drawText(5, r.top() + 5, 35, 20, Qt.AlignRight, f"{hi:g}")
+        painter.drawText(5, r.bottom() - 15, 35, 20, Qt.AlignRight, f"{lo:g}")
+
+        if len(numeric) == 1:
+            x = r.center().x()
+            y = r.bottom() - (numeric[0] - lo) / (hi - lo) * r.height()
+            painter.setBrush(QColor("#58a6ff"))
+            painter.drawEllipse(int(x - 4), int(y - 4), 8, 8)
+            return
+
+        points = []
+        count = len(numeric)
+        for i, value in enumerate(numeric):
+            x = r.left() + i * r.width() / max(1, count - 1)
+            y = r.bottom() - (value - lo) / (hi - lo) * r.height()
+            points.append((x, y))
+
+        painter.setPen(QColor("#58a6ff"))
+        for a, b in zip(points, points[1:]):
+            painter.drawLine(int(a[0]), int(a[1]), int(b[0]), int(b[1]))
+
+        painter.setBrush(QColor("#58a6ff"))
+        for x, y in points:
+            painter.drawEllipse(int(x - 3), int(y - 3), 6, 6)
+
+
+class AbacusIDE(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.core = AbacusCore()
+        self.step = 0
+        self.results = []
+
+        self.setWindowTitle("Abacus IDE")
+        self.resize(1400, 850)
+        self.setMinimumSize(1050, 650)
+
+        self._build_main()
+        self._build_menu()
+        self._build_toolbar()
+        self._build_docks()
+        self._build_statusbar()
+
+        self._refresh_sidebars()
+        self.editor.setFocus()
+
+    def _build_menu(self):
+        menu = self.menuBar()
+
+        file_menu = menu.addMenu("File")
+
+        export_action = file_menu.addAction("Export history to JSON...")
+        export_action.triggered.connect(self.export_history)
+
+        import_action = file_menu.addAction("Import history from JSON...")
+        import_action.triggered.connect(self.import_history)
+
+        file_menu.addSeparator()
+
+        reset_action = file_menu.addAction("Reset Abacus")
+        reset_action.triggered.connect(self.reset_abacus)
+
+        file_menu.addSeparator()
+
+        exit_action = file_menu.addAction("Exit")
+        exit_action.triggered.connect(self.close)
+
+        edit_menu = menu.addMenu("Edit")
+        clear_errors = edit_menu.addAction("Clear error highlighting")
+        clear_errors.triggered.connect(self.editor.clear_error_lines)
+
+    def _build_toolbar(self):
+        toolbar = QToolBar()
+        toolbar.setMovable(False)
+        toolbar.setToolButtonStyle(Qt.ToolButtonTextOnly)
+        self.addToolBar(toolbar)
+
+        run = toolbar.addAction("▶  Run")
+        run.triggered.connect(self.run_document)
+
+        run_line = toolbar.addAction("Run line")
+        run_line.triggered.connect(self.run_current_line)
+
+        toolbar.addSeparator()
+
+        for symbol in ("+", "-", "*", "/", "(", ")", "[", "]", "="):
+            button = QPushButton(symbol)
+            button.setObjectName("operator")
+            button.clicked.connect(
+                lambda checked=False, s=symbol: self.insert_operator(s)
+            )
+            toolbar.addWidget(button)
+
+        toolbar.addSeparator()
+
+        clear = toolbar.addAction("Clear")
+        clear.triggered.connect(self.editor.clear)
+
+        toolbar.addSeparator()
+
+        reset = toolbar.addAction("Reset")
+        reset.triggered.connect(self.reset_abacus)
+
+    def _build_main(self):
+        self.tabs = QTabWidget()
+        self.setCentralWidget(self.tabs)
+
+        # Workspace tab
+        workspace = QWidget()
+        workspace_layout = QVBoxLayout(workspace)
+        workspace_layout.setContentsMargins(10, 10, 10, 10)
+        workspace_layout.setSpacing(8)
+
+        editor_header = QHBoxLayout()
+        label = QLabel("Expression editor")
+        label.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+
+        hint = QLabel(
+            "One command per line  •  # comments  •  Enter = run line"
+        )
+        hint.setStyleSheet("color: #657585;")
+
+        editor_header.addWidget(label)
+        editor_header.addStretch()
+        editor_header.addWidget(hint)
+        workspace_layout.addLayout(editor_header)
+
+        self.editor = CodeEditor()
+        self.highlighter = AbacusHighlighter(self.editor.document())
+
+        self.completion_model = QStringListModel()
+        self.completer = QCompleter(self.completion_model, self)
+        self.editor.set_completer(self.completer)
+
+        self.editor.setPlainText(
+            "# Example\n"
+            "alpha = 10\n"
+            "beta = 2\n"
+            "alpha + beta * 3\n"
+        )
+        workspace_layout.addWidget(self.editor, 1)
+
+        bottom = QFrame()
+        bottom.setObjectName("bottomCard")
+        bottom_layout = QHBoxLayout(bottom)
+        bottom_layout.setContentsMargins(10, 8, 10, 8)
+
+        bottom_layout.addWidget(QLabel("Quick input:"))
+
+        self.single_line = QLineEdit()
+        self.single_line.setObjectName("singleLine")
+        self.single_line.setPlaceholderText("Enter expression...")
+        self.single_line.returnPressed.connect(self.run_single_line)
+        bottom_layout.addWidget(self.single_line, 1)
+
+        execute = QPushButton("Execute")
+        execute.clicked.connect(self.run_single_line)
+        bottom_layout.addWidget(execute)
+
+        workspace_layout.addWidget(bottom)
+
+        self.tabs.addTab(workspace, "Workspace")
+
+        # Results tab
+        results_page = QWidget()
+        results_layout = QVBoxLayout(results_page)
+        results_layout.setContentsMargins(10, 10, 10, 10)
+
+        self.results_table = QTableWidget(0, 4)
+        self.results_table.setHorizontalHeaderLabels(
+            ["Step", "Expression", "Result", "Comment"]
+        )
+        self.results_table.horizontalHeader().setStretchLastSection(True)
+        self.results_table.setAlternatingRowColors(False)
+        results_layout.addWidget(self.results_table)
+
+        self.tabs.addTab(results_page, "Results")
+
+        # Graph tab
+        graph_page = QWidget()
+        graph_layout = QVBoxLayout(graph_page)
+        graph_layout.setContentsMargins(10, 10, 10, 10)
+
+        graph_title = QLabel("Numeric result history")
+        graph_title.setStyleSheet(
+            "font-size: 13px; font-weight: 700; color: #c9d1d9;"
+        )
+        graph_layout.addWidget(graph_title)
+
+        self.graph = ResultGraph()
+        graph_layout.addWidget(self.graph, 1)
+
+        graph_info = QLabel(
+            "The graph uses numeric results from executed expressions."
+        )
+        graph_info.setStyleSheet("color: #657585;")
+        graph_layout.addWidget(graph_info)
+
+        self.tabs.addTab(graph_page, "Graph")
+
+    def _build_docks(self):
+        self.variables_dock = self._make_dock(
+            "Variables", self._make_list_widget()
+        )
+        self.functions_dock = self._make_dock(
+            "Functions", self._make_list_widget()
+        )
+        self.history_dock = self._make_dock(
+            "History", self._make_list_widget()
+        )
+
+        self.variables_list = self.variables_dock.widget()
+        self.functions_list = self.functions_dock.widget()
+        self.history_list = self.history_dock.widget()
+
+        self.addDockWidget(Qt.RightDockWidgetArea, self.variables_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.functions_dock)
+        self.addDockWidget(Qt.RightDockWidgetArea, self.history_dock)
+
+        self.tabifyDockWidget(self.variables_dock, self.functions_dock)
+        self.tabifyDockWidget(self.functions_dock, self.history_dock)
+        self.variables_dock.raise_()
+
+    def _make_list_widget(self):
+        return QListWidget()
+
+    def _make_dock(self, title, widget):
+        dock = QDockWidget(title, self)
+        dock.setAllowedAreas(
+            Qt.LeftDockWidgetArea | Qt.RightDockWidgetArea
+        )
+        dock.setFeatures(
+            QDockWidget.DockWidgetMovable
+            | QDockWidget.DockWidgetFloatable
+        )
+        dock.setWidget(widget)
+        return dock
+
+    def _build_statusbar(self):
+        self.status = QStatusBar()
+        self.setStatusBar(self.status)
+        self.status.showMessage("Ready")
+
+    def insert_operator(self, symbol):
+        self.editor.insertPlainText(symbol)
+        self.editor.setFocus()
+
+    def run_single_line(self):
+        text = self.single_line.text().strip()
+        if not text:
+            return
+
+        self._execute(text)
+        self.single_line.clear()
+
+    def run_current_line(self):
+        cursor = self.editor.textCursor()
+        cursor.select(cursor.LineUnderCursor)
+        line = cursor.selectedText().strip()
+
+        if line:
+            self.editor.clear_error_lines()
+            line_number = cursor.blockNumber() + 1
+            self._execute(line, line_number)
+
+    def run_document(self):
+        self.editor.clear_error_lines()
+        lines = self.editor.toPlainText().splitlines()
+
+        executed = 0
+        failed = 0
+
+        for line_index, line in enumerate(lines, start=1):
+            stripped = line.strip()
+            if not stripped or stripped.startswith("#"):
+                continue
+
+            if self._execute(stripped, line_index):
+                executed += 1
+            else:
+                failed += 1
+
+        if failed:
+            self.status.showMessage(
+                f"Executed {executed} command(s), {failed} error(s)"
+            )
+        else:
+            self.status.showMessage(f"Executed {executed} command(s)")
+
+    def _execute(self, text, line_number=None):
+        self.step += 1
+
+        try:
+            result = self.core.parse_input(text)
+        except Exception as exc:
+            self.step -= 1
+            self.status.showMessage(f"Error: {exc}")
+
+            if line_number is not None:
+                self.editor.set_error_lines({
+                    line_number: str(exc),
+                })
+
+            self.history_list.addItem(
+                f"ERROR  line {line_number or '?'}  {text}  →  {exc}"
+            )
+            return False
+
+        # Critical: assignments/functions return None, but their
+        # dictionaries are already changed. Refresh immediately.
+        self._refresh_sidebars()
+
+        if not result:
+            self.status.showMessage(f"Updated: {text}")
+            return True
+
+        original, _, value, comment = result
+        value_text = str(value)
+        comment_text = comment or ""
+
+        self.results.append(
+            {
+                "step": self.step,
+                "expression": original,
+                "result": value_text,
+                "comment": comment_text,
+            }
+        )
+
+        self.history_list.addItem(
+            f"{self.step}.  {original}  =  {value_text}"
+        )
+        self.history_list.scrollToBottom()
+
+        self._add_result_row(
+            self.step, original, value_text, comment_text
+        )
+
+        try:
+            numeric = float(value)
+        except (TypeError, ValueError):
+            numeric = None
+
+        if numeric is not None and math.isfinite(numeric):
+            self.graph.values.append(numeric)
+            self.graph.set_values(self.graph.values)
+
+        self.status.showMessage(f"Result: {value_text}")
+        return True
+
+    def _add_result_row(self, step, expression, result, comment):
+        row = self.results_table.rowCount()
+        self.results_table.insertRow(row)
+
+        values = [str(step), expression, result, comment]
+
+        for col, value in enumerate(values):
+            self.results_table.setItem(
+                row, col, QTableWidgetItem(value)
+            )
+
+        self.results_table.resizeColumnsToContents()
+        self.results_table.scrollToBottom()
+
+    def _refresh_sidebars(self):
+        self.variables_list.clear()
+
+        for key, value in self.core.get_vars().items():
+            self.variables_list.addItem(f"{key}    =    {value}")
+
+        self.functions_list.clear()
+
+        functions = self.core.get_funcs()
+
+        for key, value in functions.items():
+            self.functions_list.addItem(f"{key}    =    {value}")
+
+        names = list(self.core.get_vars().keys()) + list(functions.keys())
+        self.completion_model.setStringList(sorted(set(names)))
+
+    def export_history(self):
+        path, _ = QFileDialog.getSaveFileName(
+            self,
+            "Export history",
+            "abacus_history.json",
+            "JSON files (*.json)",
+        )
+        if not path:
+            return
+
+        data = {
+            "format": "abacus-history",
+            "version": 1,
+            "step": self.step,
+            "document": self.editor.toPlainText(),
+            "history": [
+                self.history_list.item(i).text()
+                for i in range(self.history_list.count())
+            ],
+            "results": self.results,
+            "graph_values": self.graph.values,
+        }
+
+        try:
+            with open(path, "w", encoding="utf-8") as file:
+                json.dump(
+                    data,
+                    file,
+                    ensure_ascii=False,
+                    indent=2,
+                )
+        except OSError as exc:
+            self.status.showMessage(f"Export error: {exc}")
+            return
+
+        self.status.showMessage(f"History exported: {path}")
+
+    def import_history(self):
+        path, _ = QFileDialog.getOpenFileName(
+            self,
+            "Import history",
+            "",
+            "JSON files (*.json)",
+        )
+        if not path:
+            return
+
+        try:
+            with open(path, "r", encoding="utf-8") as file:
+                data = json.load(file)
+
+            if data.get("format") != "abacus-history":
+                raise ValueError("Not an Abacus history file")
+
+            if data.get("version") != 1:
+                raise ValueError(
+                    f"Unsupported history version: {data.get('version')}"
+                )
+
+            history = data.get("history", [])
+            results = data.get("results", [])
+            graph_values = data.get("graph_values", [])
+            document = data.get("document", "")
+            step = int(data.get("step", len(results)))
+
+            if not isinstance(history, list):
+                raise ValueError("Invalid history data")
+            if not isinstance(results, list):
+                raise ValueError("Invalid results data")
+            if not isinstance(graph_values, list):
+                raise ValueError("Invalid graph data")
+
+        except (OSError, ValueError, TypeError, json.JSONDecodeError) as exc:
+            self.status.showMessage(f"Import error: {exc}")
+            return
+
+        self.step = step
+        self.results = results
+
+        self.history_list.clear()
+        self.history_list.addItems(
+            str(item) for item in history
+        )
+
+        self.results_table.setRowCount(0)
+        for item in self.results:
+            self._add_result_row(
+                item.get("step", ""),
+                item.get("expression", ""),
+                item.get("result", ""),
+                item.get("comment", ""),
+            )
+
+        self.graph.set_values(
+            [float(value) for value in graph_values]
+            if graph_values
+            else []
+        )
+
+        if document:
+            self.editor.setPlainText(document)
+
+        self.status.showMessage(f"History imported: {path}")
+
+    def reset_abacus(self):
+        self.core = AbacusCore()
+        self.step = 0
+        self.results.clear()
+
+        self.variables_list.clear()
+        self.functions_list.clear()
+        self.history_list.clear()
+        self.results_table.setRowCount(0)
+
+        self.graph.set_values([])
+        self.editor.clear_error_lines()
+        self._refresh_sidebars()
+        self.status.showMessage("Abacus state reset")
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+    app.setStyleSheet(STYLE)
+
+    window = AbacusIDE()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/abacus_pyside6.py b/abacus_pyside6.py
new file mode 100644
index 0000000..2ee36b6
--- /dev/null
+++ b/abacus_pyside6.py
@@ -0,0 +1,354 @@
+import sys
+
+from PySide6.QtCore import Qt
+from PySide6.QtGui import QFont
+from PySide6.QtWidgets import (
+    QApplication,
+    QFrame,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListWidget,
+    QMainWindow,
+    QPushButton,
+    QSplitter,
+    QVBoxLayout,
+    QWidget,
+)
+
+from abacus_core import AbacusCore
+
+
+STYLE = """
+QMainWindow, QWidget {
+    background: #111318;
+    color: #e7e9ee;
+    font-family: "Segoe UI";
+    font-size: 13px;
+}
+
+QFrame#topbar {
+    background: #171a21;
+    border-bottom: 1px solid #292e38;
+}
+
+QLabel#title {
+    font-size: 20px;
+    font-weight: 700;
+    color: #f5f7fb;
+}
+
+QLabel#subtitle {
+    color: #858c99;
+}
+
+QFrame#panel {
+    background: #171a21;
+    border: 1px solid #292e38;
+    border-radius: 12px;
+}
+
+QLabel#panelTitle {
+    color: #9da5b3;
+    font-size: 12px;
+    font-weight: 700;
+}
+
+QLineEdit#input {
+    background: #0d0f13;
+    border: 1px solid #343a46;
+    border-radius: 10px;
+    padding: 12px 14px;
+    color: #ffffff;
+    font-size: 16px;
+    selection-background-color: #3b82f6;
+}
+
+QLineEdit#input:focus {
+    border: 1px solid #4b8cff;
+}
+
+QPushButton {
+    background: #2864d7;
+    border: none;
+    border-radius: 9px;
+    padding: 11px 18px;
+    color: white;
+    font-weight: 700;
+}
+
+QPushButton:hover {
+    background: #3475ef;
+}
+
+QPushButton:pressed {
+    background: #1f55ba;
+}
+
+QPushButton#secondary {
+    background: #242933;
+    color: #cbd1db;
+}
+
+QPushButton#secondary:hover {
+    background: #2d333f;
+}
+
+QListWidget {
+    background: transparent;
+    border: none;
+    outline: none;
+    padding: 4px;
+}
+
+QListWidget::item {
+    padding: 8px 7px;
+    border-radius: 7px;
+}
+
+QListWidget::item:hover {
+    background: #20242d;
+}
+
+QListWidget::item:selected {
+    background: #202a3d;
+    color: #ffffff;
+}
+
+QLabel#result {
+    color: #66d9a8;
+    font-size: 28px;
+    font-weight: 700;
+}
+
+QLabel#status {
+    color: #7e8795;
+}
+
+QSplitter::handle {
+    background: #111318;
+    width: 8px;
+}
+"""
+
+
+class AbacusWindow(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.abacus = AbacusCore()
+        self.step = 0
+
+        self.setWindowTitle("Abacus")
+        self.resize(1100, 720)
+        self.setMinimumSize(850, 560)
+
+        self._build_ui()
+        self._update_lists()
+
+    def _build_ui(self):
+        root = QWidget()
+        root_layout = QVBoxLayout(root)
+        root_layout.setContentsMargins(18, 14, 18, 18)
+        root_layout.setSpacing(14)
+
+        # Header
+        topbar = QFrame()
+        topbar.setObjectName("topbar")
+        top_layout = QHBoxLayout(topbar)
+        top_layout.setContentsMargins(4, 4, 4, 12)
+
+        title_box = QVBoxLayout()
+        title_box.setSpacing(1)
+
+        title = QLabel("Abacus")
+        title.setObjectName("title")
+
+        subtitle = QLabel("Expression calculator")
+        subtitle.setObjectName("subtitle")
+
+        title_box.addWidget(title)
+        title_box.addWidget(subtitle)
+        top_layout.addLayout(title_box)
+        top_layout.addStretch()
+
+        self.status = QLabel("Ready")
+        self.status.setObjectName("status")
+        top_layout.addWidget(self.status)
+
+        root_layout.addWidget(topbar)
+
+        splitter = QSplitter(Qt.Horizontal)
+        splitter.setChildrenCollapsible(False)
+
+        # Left: history
+        history_panel = self._make_panel("History")
+        history_layout = history_panel.layout()
+
+        self.history = QListWidget()
+        self.history.setAlternatingRowColors(False)
+        history_layout.addWidget(self.history)
+
+        clear_btn = QPushButton("Clear history")
+        clear_btn.setObjectName("secondary")
+        clear_btn.clicked.connect(self.history.clear)
+        history_layout.addWidget(clear_btn)
+
+        splitter.addWidget(history_panel)
+
+        # Center
+        center = QWidget()
+        center_layout = QVBoxLayout(center)
+        center_layout.setContentsMargins(0, 0, 0, 0)
+        center_layout.setSpacing(14)
+
+        calc_panel = self._make_panel("Calculator")
+        calc_layout = calc_panel.layout()
+
+        self.result = QLabel("0")
+        self.result.setObjectName("result")
+        self.result.setAlignment(Qt.AlignRight | Qt.AlignVCenter)
+        calc_layout.addWidget(self.result)
+
+        self.input = QLineEdit()
+        self.input.setObjectName("input")
+        self.input.setPlaceholderText("Enter expression, e.g. 2 + 3 * alpha")
+        self.input.returnPressed.connect(self.calculate)
+        calc_layout.addWidget(self.input)
+
+        buttons = QHBoxLayout()
+        buttons.setSpacing(8)
+
+        enter = QPushButton("Calculate")
+        enter.clicked.connect(self.calculate)
+
+        clear = QPushButton("Clear")
+        clear.setObjectName("secondary")
+        clear.clicked.connect(self._clear_input)
+
+        buttons.addWidget(enter)
+        buttons.addWidget(clear)
+        calc_layout.addLayout(buttons)
+
+        center_layout.addWidget(calc_panel)
+
+        help_panel = self._make_panel("Quick reference")
+        help_layout = help_panel.layout()
+
+        help_text = QLabel(
+            "Variable:  alpha = 10\n"
+            "Function:  double: alpha * 2\n"
+            "Comment:   2 + 3 # test\n"
+            "Commands from the original console are available through the UI."
+        )
+        help_text.setStyleSheet("color: #9da5b3; line-height: 1.5;")
+        help_text.setWordWrap(True)
+        help_layout.addWidget(help_text)
+        center_layout.addWidget(help_panel)
+        center_layout.addStretch()
+
+        splitter.addWidget(center)
+
+        # Right: variables/functions
+        right = QWidget()
+        right_layout = QVBoxLayout(right)
+        right_layout.setContentsMargins(0, 0, 0, 0)
+        right_layout.setSpacing(14)
+
+        var_panel = self._make_panel("Variables")
+        var_panel.layout().addWidget(QLabel("Stored values"))
+        self.variables = QListWidget()
+        var_panel.layout().addWidget(self.variables)
+        right_layout.addWidget(var_panel, 1)
+
+        func_panel = self._make_panel("Functions")
+        func_panel.layout().addWidget(QLabel("Definitions"))
+        self.functions = QListWidget()
+        func_panel.layout().addWidget(self.functions)
+        right_layout.addWidget(func_panel, 1)
+
+        splitter.addWidget(right)
+
+        splitter.setSizes([260, 500, 280])
+        root_layout.addWidget(splitter, 1)
+
+        self.setCentralWidget(root)
+
+    def _make_panel(self, title):
+        panel = QFrame()
+        panel.setObjectName("panel")
+
+        layout = QVBoxLayout(panel)
+        layout.setContentsMargins(14, 13, 14, 14)
+        layout.setSpacing(9)
+
+        label = QLabel(title)
+        label.setObjectName("panelTitle")
+        layout.addWidget(label)
+
+        return panel
+
+    def calculate(self):
+        text = self.input.text().strip()
+        if not text:
+            return
+
+        self.step += 1
+
+        try:
+            result = self.abacus.parse_input(text)
+        except Exception as exc:
+            self.status.setText(f"Error: {exc}")
+            self.result.setText("Error")
+            return
+
+        if not result:
+            self.input.clear()
+            self.status.setText("Comment / empty input")
+            return
+
+        original, _, value, comment = result
+        value_text = str(value)
+
+        line = f"{self.step}.  {original}  =  {value_text}"
+        if comment:
+            line += f"   #{comment}"
+
+        self.history.addItem(line)
+        self.history.scrollToBottom()
+
+        self.result.setText(value_text)
+        self.input.setText(value_text)
+        self.status.setText("Calculated")
+        self._update_lists()
+
+    def _clear_input(self):
+        self.input.clear()
+        self.result.setText("0")
+        self.status.setText("Ready")
+        self.input.setFocus()
+
+    def _update_lists(self):
+        self.variables.clear()
+        for key, value in self.abacus.get_vars().items():
+            self.variables.addItem(f"{key}  =  {value}")
+
+        self.functions.clear()
+        for key, value in self.abacus.get_funcs().items():
+            self.functions.addItem(f"{key}  =  {value}")
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+    app.setFont(QFont("Segoe UI", 10))
+    app.setStyleSheet(STYLE)
+
+    window = AbacusWindow()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/abacus_pyside6_v2.py b/abacus_pyside6_v2.py
new file mode 100644
index 0000000..1cac1a7
--- /dev/null
+++ b/abacus_pyside6_v2.py
@@ -0,0 +1,360 @@
+import sys
+
+from PySide6.QtCore import Qt
+from PySide6.QtGui import QFont
+from PySide6.QtWidgets import (
+    QApplication,
+    QFrame,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListWidget,
+    QMainWindow,
+    QPushButton,
+    QSplitter,
+    QVBoxLayout,
+    QWidget,
+)
+
+from abacus_core import AbacusCore
+
+
+STYLE = """
+QMainWindow, QWidget {
+    background: #111318;
+    color: #e7e9ee;
+    font-family: "Segoe UI";
+    font-size: 13px;
+}
+
+QFrame#topbar {
+    background: #111820;
+    border-bottom: 1px solid #292e38;
+}
+
+QLabel#title {
+    font-size: 22px;
+    font-weight: 700;
+    color: #f5f7fb;
+}
+
+QLabel#subtitle {
+    color: #858c99;
+}
+
+QFrame#panel {
+    background: #111820;
+    border: 1px solid #202a36;
+    border-radius: 12px;
+}
+
+QLabel#panelTitle {
+    color: #9da5b3;
+    font-size: 12px;
+    font-weight: 700;
+}
+
+QLineEdit#input {
+    background: #0d0f13;
+    border: 1px solid #343a46;
+    border-radius: 10px;
+    padding: 12px 14px;
+    color: #ffffff;
+    font-size: 16px;
+    selection-background-color: #3b82f6;
+}
+
+QLineEdit#input:focus {
+    border: 1px solid #4b8cff;
+}
+
+QPushButton {
+    background: #2864d7;
+    border: none;
+    border-radius: 9px;
+    padding: 11px 18px;
+    color: white;
+    font-weight: 700;
+}
+
+QPushButton:hover {
+    background: #3475ef;
+}
+
+QPushButton:pressed {
+    background: #1f55ba;
+}
+
+QPushButton#secondary {
+    background: #242933;
+    color: #cbd1db;
+}
+
+QPushButton#secondary:hover {
+    background: #2d333f;
+}
+
+QListWidget {
+    background: #0d131a;
+    border: 1px solid #202a36;
+    border-radius: 10px;
+    outline: none;
+    padding: 5px;
+}
+
+QListWidget::item {
+    padding: 8px 7px;
+    border-radius: 7px;
+}
+
+QListWidget::item:hover {
+    background: #20242d;
+}
+
+QListWidget::item:selected {
+    background: #202a3d;
+    color: #ffffff;
+}
+
+QLabel#result {
+    color: #66d9a8;
+    font-size: 28px;
+    font-weight: 700;
+}
+
+QLabel#status {
+    color: #7e8795;
+}
+
+QSplitter::handle {
+    background: #111318;
+    width: 8px;
+}
+"""
+
+
+class AbacusWindow(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.abacus = AbacusCore()
+        self.step = 0
+
+        self.setWindowTitle("Abacus")
+        self.resize(1180, 760)
+        self.setMinimumSize(850, 560)
+
+        self._build_ui()
+        self._update_lists()
+
+    def _build_ui(self):
+        root = QWidget()
+        root_layout = QVBoxLayout(root)
+        root_layout.setContentsMargins(18, 14, 18, 18)
+        root_layout.setSpacing(14)
+
+        # Header
+        topbar = QFrame()
+        topbar.setObjectName("topbar")
+        top_layout = QHBoxLayout(topbar)
+        top_layout.setContentsMargins(4, 4, 4, 12)
+
+        title_box = QVBoxLayout()
+        title_box.setSpacing(1)
+
+        title = QLabel("Abacus")
+        title.setObjectName("title")
+
+        subtitle = QLabel("Expression calculator")
+        subtitle.setObjectName("subtitle")
+
+        title_box.addWidget(title)
+        title_box.addWidget(subtitle)
+        top_layout.addLayout(title_box)
+        top_layout.addStretch()
+
+        self.status = QLabel("Ready")
+        self.status.setObjectName("status")
+        top_layout.addWidget(self.status)
+
+        root_layout.addWidget(topbar)
+
+        splitter = QSplitter(Qt.Horizontal)
+        splitter.setChildrenCollapsible(False)
+
+        # Left: history
+        history_panel = self._make_panel("History")
+        history_layout = history_panel.layout()
+
+        self.history = QListWidget()
+        self.history.setAlternatingRowColors(False)
+        history_layout.addWidget(self.history)
+
+        clear_btn = QPushButton("Clear history")
+        clear_btn.setObjectName("secondary")
+        clear_btn.clicked.connect(self.history.clear)
+        history_layout.addWidget(clear_btn)
+
+        splitter.addWidget(history_panel)
+
+        # Center
+        center = QWidget()
+        center_layout = QVBoxLayout(center)
+        center_layout.setContentsMargins(0, 0, 0, 0)
+        center_layout.setSpacing(14)
+
+        calc_panel = self._make_panel("Calculator")
+        calc_layout = calc_panel.layout()
+
+        self.result = QLabel("0")
+        self.result.setObjectName("result")
+        self.result.setAlignment(Qt.AlignRight | Qt.AlignVCenter)
+        calc_layout.addWidget(self.result)
+
+        self.input = QLineEdit()
+        self.input.setObjectName("input")
+        self.input.setPlaceholderText("Enter expression, e.g. 2 + 3 * alpha")
+        self.input.returnPressed.connect(self.calculate)
+        calc_layout.addWidget(self.input)
+
+        buttons = QHBoxLayout()
+        buttons.setSpacing(8)
+
+        enter = QPushButton("Calculate")
+        enter.clicked.connect(self.calculate)
+
+        clear = QPushButton("Clear")
+        clear.setObjectName("secondary")
+        clear.clicked.connect(self._clear_input)
+
+        buttons.addWidget(enter)
+        buttons.addWidget(clear)
+        calc_layout.addLayout(buttons)
+
+        center_layout.addWidget(calc_panel)
+
+        help_panel = self._make_panel("Quick reference")
+        help_layout = help_panel.layout()
+
+        help_text = QLabel(
+            "Variable:  alpha = 10\n"
+            "Function:  double: alpha * 2\n"
+            "Comment:   2 + 3 # test\n"
+            "Commands from the original console are available through the UI."
+        )
+        help_text.setStyleSheet("color: #9da5b3; line-height: 1.5;")
+        help_text.setWordWrap(True)
+        help_layout.addWidget(help_text)
+        center_layout.addWidget(help_panel)
+        center_layout.addStretch()
+
+        splitter.addWidget(center)
+
+        # Right: variables/functions
+        right = QWidget()
+        right_layout = QVBoxLayout(right)
+        right_layout.setContentsMargins(0, 0, 0, 0)
+        right_layout.setSpacing(14)
+
+        var_panel = self._make_panel("Variables")
+        var_panel.layout().addWidget(QLabel("Stored values"))
+        self.variables = QListWidget()
+        var_panel.layout().addWidget(self.variables)
+        right_layout.addWidget(var_panel, 1)
+
+        func_panel = self._make_panel("Functions")
+        func_panel.layout().addWidget(QLabel("Definitions"))
+        self.functions = QListWidget()
+        func_panel.layout().addWidget(self.functions)
+        right_layout.addWidget(func_panel, 1)
+
+        splitter.addWidget(right)
+
+        splitter.setSizes([260, 500, 280])
+        root_layout.addWidget(splitter, 1)
+
+        self.setCentralWidget(root)
+
+    def _make_panel(self, title):
+        panel = QFrame()
+        panel.setObjectName("panel")
+
+        layout = QVBoxLayout(panel)
+        layout.setContentsMargins(14, 13, 14, 14)
+        layout.setSpacing(9)
+
+        label = QLabel(title)
+        label.setObjectName("panelTitle")
+        layout.addWidget(label)
+
+        return panel
+
+    def calculate(self):
+        text = self.input.text().strip()
+        if not text:
+            return
+
+        self.step += 1
+
+        try:
+            result = self.abacus.parse_input(text)
+        except Exception as exc:
+            self.step -= 1
+            self.status.setText(f"Error: {exc}")
+            self.result.setText("Error")
+            return
+
+        # Assignments return None from AbacusCore.parse_input().
+        # Refresh the side panels BEFORE handling the result.
+        self._update_lists()
+
+        if not result:
+            self.input.clear()
+            self.status.setText("Updated")
+            return
+
+        original, _, value, comment = result
+        value_text = str(value)
+
+        line = f"{self.step}.  {original}  =  {value_text}"
+        if comment:
+            line += f"   #{comment}"
+
+        self.history.addItem(line)
+        self.history.scrollToBottom()
+
+        self.result.setText(value_text)
+        self.input.setText(value_text)
+        self.status.setText("Calculated")
+        self._update_lists()
+
+    def _clear_input(self):
+        self.input.clear()
+        self.result.setText("0")
+        self.status.setText("Ready")
+        self.input.setFocus()
+
+    def _update_lists(self):
+        self.variables.clear()
+        for key, value in self.abacus.get_vars().items():
+            self.variables.addItem(f"{key}  =  {value}")
+
+        self.functions.clear()
+        for key, value in self.abacus.get_funcs().items():
+            self.functions.addItem(f"{key}  =  {value}")
+
+
+def main():
+    app = QApplication(sys.argv)
+    app.setStyle("Fusion")
+    app.setFont(QFont("Segoe UI", 10))
+    app.setStyleSheet(STYLE)
+
+    window = AbacusWindow()
+    window.show()
+
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":
+    main()
diff --git a/dieselfloater_edeka.json b/dieselfloater_edeka.json
new file mode 100644
index 0000000..0bb910a
--- /dev/null
+++ b/dieselfloater_edeka.json
@@ -0,0 +1,30 @@
+{
+  "format": "abacus-history",
+  "version": 1,
+  "step": 4,
+  "document": "dieselpreis=1,99\nbasisfracht=200\npercent=20\nbasisfracht*(percent/100)*dieselpreis",
+  "variables": {
+    "result": 79.6,
+    "alphabet": 28,
+    "alpha": 1,
+    "beta": 2,
+    "dieselpreis": 1.99,
+    "basisfracht": 200,
+    "percent": 20
+  },
+  "functions": {},
+  "history": [
+    "4.  basisfracht*(percent/100)*dieselpreis  =  79.6"
+  ],
+  "results": [
+    {
+      "step": 4,
+      "expression": "basisfracht*(percent/100)*dieselpreis",
+      "result": "79.6",
+      "comment": ""
+    }
+  ],
+  "graph_values": [
+    79.6
+  ]
+}
\ No newline at end of file
diff --git a/test.json b/test.json
new file mode 100644
index 0000000..7135bea
--- /dev/null
+++ b/test.json
@@ -0,0 +1,46 @@
+{
+  "format": "abacus-history",
+  "version": 1,
+  "step": 7,
+  "document": "alpha=35\nbeta=22\nalpha+beta\ndouble:result*2\ndouble\ntriple:result*3\ntriple+double+22",
+  "variables": {
+    "result": 592,
+    "alphabet": 28,
+    "alpha": 35,
+    "beta": 22
+  },
+  "functions": {
+    "double": "result*2",
+    "triple": "result*3"
+  },
+  "history": [
+    "3.  alpha+beta  =  57",
+    "5.  double  =  114",
+    "7.  triple+double+22  =  592"
+  ],
+  "results": [
+    {
+      "step": 3,
+      "expression": "alpha+beta",
+      "result": "57",
+      "comment": ""
+    },
+    {
+      "step": 5,
+      "expression": "double",
+      "result": "114",
+      "comment": ""
+    },
+    {
+      "step": 7,
+      "expression": "triple+double+22",
+      "result": "592",
+      "comment": ""
+    }
+  ],
+  "graph_values": [
+    57.0,
+    114.0,
+    592.0
+  ]
+}
\ No newline at end of file