Phase 7: shop Inventory window + stats

- gui/inventory_window.py: read-only management view over the event ledger —
  On-hand / Offcut bin / Build history / Stats tabs (shop-wide), with Refresh.
- Wired into the main window: new Shop ▸ Inventory… menu.
- Plan doc marked complete (all 7 phases; offcut reuse opt-in toggle, purchase
  price-book update opt-in).
- tests: window renders a populated ledger and an empty one.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

MATERIALS_INVENTORY_PLAN.md

@@ -1,7 +1,9 @@
 # Materials, Finish, Batch Builds & Shop Inventory — Plan (v2, reconciled)
 
 Design plan for four related features, reconciled after a Codex review.
-Nothing built yet. v2 changes vs v1 are marked **[v2]**.
+**STATUS: all 7 phases implemented (193 tests).** v2 changes vs v1 are marked **[v2]**.
+Settled the two trailing questions: offcut reuse is **opt-in** (a toggle), and
+recording a purchase **opt-in** saves prices to the price book.
 
 ## What changed in v2 (after Codex review)
 - **[v2] Sanding never shrinks the design model.** Part dims = final/intended.

src/woodshop/gui/inventory_window.py

@@ -0,0 +1,95 @@
+"""The shop Inventory window — a read-only management view over the event
+ledger (on-hand stock, offcut bin, build history, stats). The day-to-day
+workflows (mark purchased / record build / use offcuts) live on the BOM window;
+this is where you review and audit. Shop-wide across all projects."""
+from __future__ import annotations
+
+from PySide6.QtGui import QFont
+from PySide6.QtWidgets import (QDialog, QHBoxLayout, QPushButton, QTabWidget,
+                               QTextEdit, QVBoxLayout, QWidget)
+
+from .. import inventory as inventory_mod
+
+
+class InventoryWindow(QDialog):
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self.setWindowTitle("Shop Inventory")
+        self.resize(640, 520)
+        self._ledger = inventory_mod.Ledger.load()
+
+        self._tabs = {}
+        tabw = QTabWidget()
+        for name in ("On-hand", "Offcut bin", "Build history", "Stats"):
+            te = QTextEdit(readOnly=True)
+            te.setFont(QFont("monospace"))
+            self._tabs[name] = te
+            tabw.addTab(te, name)
+
+        root = QVBoxLayout(self)
+        root.addWidget(tabw)
+        row = QHBoxLayout()
+        refresh = QPushButton("Refresh")
+        refresh.clicked.connect(self.reload)
+        row.addStretch(); row.addWidget(refresh)
+        root.addLayout(row)
+        self.reload()
+
+    def reload(self) -> None:
+        self._ledger = inventory_mod.Ledger.load()
+        self._tabs["On-hand"].setPlainText(self._on_hand_text())
+        self._tabs["Offcut bin"].setPlainText(self._offcuts_text())
+        self._tabs["Build history"].setPlainText(self._builds_text())
+        self._tabs["Stats"].setPlainText(self._stats_text())
+
+    def _on_hand_text(self) -> str:
+        oh = self._ledger.on_hand()
+        if not oh:
+            return "ON-HAND STOCK\n\n  (empty — Mark purchased on the BOM window to add)"
+        lines = ["ON-HAND STOCK", ""]
+        for stock, qty in oh.items():
+            unit = "sheet" if stock.startswith("ply-") else "stick"
+            lines.append(f"  {qty:>3} × {stock:<10} ({unit}s)")
+        return "\n".join(lines)
+
+    def _offcuts_text(self) -> str:
+        bin_ = self._ledger.offcut_bin()
+        if not bin_:
+            return "OFFCUT BIN\n\n  (empty — kept offcuts from recorded builds land here)"
+        lines = ["OFFCUT BIN", ""]
+        for p in sorted(bin_, key=lambda p: (p.stock, -p.length_in)):
+            if p.is_sheet:
+                size = f"{p.length_in:g}\" × {p.width_in:g}\""
+            else:
+                size = f"{p.length_in:g}\""
+            src = f"  from {p.source_project}" if p.source_project else ""
+            lines.append(f"  {p.stock:<10} {size:<14} [{p.id}]{src}")
+        return "\n".join(lines)
+
+    def _builds_text(self) -> str:
+        builds = self._ledger.builds()
+        if not builds:
+            return "BUILD HISTORY\n\n  (no builds recorded yet)"
+        lines = ["BUILD HISTORY", ""]
+        for e in builds:
+            cost = f"  ${e['cost']:,.2f}" if e.get("cost") is not None else ""
+            date = f"  {e['date']}" if e.get("date") else ""
+            lines.append(f"  {e['build_id']:<5} {e['project']:<16} ×{e['units']}{cost}{date}")
+        return "\n".join(lines)
+
+    def _stats_text(self) -> str:
+        s = self._ledger.stats()
+        lines = ["SHOP STATS", "",
+                 f"  Total spent           ${s['spent']:,.2f}",
+                 f"  Builds recorded       {s['builds']}",
+                 f"  Units built           {s['units_built']}",
+                 f"  Offcuts kept          {s['offcuts_kept']}",
+                 f"  Offcuts burned        {s['offcuts_burned']}",
+                 f"  Offcuts trashed       {s['offcuts_trashed']}",
+                 "", "  Units built by project:"]
+        if s["by_project"]:
+            for proj, n in sorted(s["by_project"].items()):
+                lines.append(f"    {proj:<18} {n}")
+        else:
+            lines.append("    (none)")
+        return "\n".join(lines)

src/woodshop/gui/main_window.py

@@ -119,6 +119,9 @@ class MainWindow(QMainWindow):
             "build a bookshelf side: two {H} 2x4 uprights {W} apart with {N} shelves of 1x8 between them",
             [("Height", "48 in"), ("Width", "12 in"), ("Shelves", "3")]))
 
+        s = mb.addMenu("&Shop")
+        self._act(s, "Inventory…", self._show_inventory)
+
         h = mb.addMenu("&Help")
         self._act(h, "Commands…", self._show_help)
 
@@ -184,6 +187,11 @@ class MainWindow(QMainWindow):
         self._bom = BomWindow(self.controller, self)   # keep a ref so it isn't GC'd
         self._bom.show()
 
+    def _show_inventory(self):
+        from .inventory_window import InventoryWindow
+        self._inventory = InventoryWindow(self)   # keep a ref so it isn't GC'd
+        self._inventory.show()
+
     def _show_help(self):
         QMessageBox.information(self, "Commands", _HELP)
 

tests/test_inventory_window.py

@@ -0,0 +1,37 @@
+"""Offscreen tests for the Inventory window (read-only management view)."""
+import os
+
+import pytest
+
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+pytest.importorskip("PySide6")
+
+from PySide6.QtWidgets import QApplication  # noqa: E402
+
+from woodshop import inventory as I  # noqa: E402
+from woodshop.gui.inventory_window import InventoryWindow  # noqa: E402
+
+_app = QApplication.instance() or QApplication([])
+
+
+def test_window_renders_ledger(tmp_path, monkeypatch):
+    monkeypatch.setenv("XDG_DATA_HOME", str(tmp_path / "data"))
+    led = I.Ledger()
+    led.purchase("2x4", 5, price=3.98)
+    led.record_build("table", 2, consumed={"2x4": 2}, offcuts=[
+        {"stock": "2x4", "length_in": 30, "width_in": 3.5, "is_sheet": False}],
+        dispositions=["keep"])
+    led.save()
+    w = InventoryWindow()
+    assert "2x4" in w._tabs["On-hand"].toPlainText()
+    assert "OFFCUT" in w._tabs["Offcut bin"].toPlainText()
+    assert "table" in w._tabs["Build history"].toPlainText()
+    stats = w._tabs["Stats"].toPlainText()
+    assert "Units built" in stats and "2" in stats
+
+
+def test_empty_ledger_renders(tmp_path, monkeypatch):
+    monkeypatch.setenv("XDG_DATA_HOME", str(tmp_path / "data"))
+    w = InventoryWindow()
+    assert "empty" in w._tabs["On-hand"].toPlainText().lower()
+    assert "no builds" in w._tabs["Build history"].toPlainText().lower()