diff --git a/app/models/part_label.py b/app/models/part_label.py
new file mode 100644
index 0000000..680fa31
--- /dev/null
+++ b/app/models/part_label.py
@@ -0,0 +1,201 @@
+"""
+Parts drawer labelling: the category tree and the labels themselves.
+
+Two tables:
+
+  * part_categories - a self-referencing tree, two levels deep in the seed
+    data but the model imposes no depth limit. Seeded from
+    app/data/part_taxonomy.json, then yours to edit.
+  * part_labels - one physical label. A label belongs to a category and
+    describes what lives in one drawer or bag.
+
+A label deliberately has no quantity or inventory field. This is a labelling
+system, not a parts inventory - the drawer tells you how many you have.
+
+Created by: Jess Rogerson (yelling commands at Claude.AI)
+"""
+
+from datetime import datetime
+import re
+
+from app import db
+
+
+def slugify(value):
+    """Lowercase, hyphenated, ASCII-ish. Used as the stable category key."""
+    value = (value or '').strip().lower()
+    value = re.sub(r'[^a-z0-9]+', '-', value)
+    return value.strip('-') or 'category'
+
+
+class PartCategory(db.Model):
+    """A node in the parts taxonomy."""
+
+    __tablename__ = 'part_categories'
+
+    id = db.Column(db.Integer, primary_key=True)
+    # Display code, e.g. "08.02". Free text: renumber however you like.
+    code = db.Column(db.String(16), nullable=True, index=True)
+    name = db.Column(db.String(120), nullable=False)
+    # Stable key used by the seeder so re-seeding never duplicates a row.
+    slug = db.Column(db.String(140), unique=True, nullable=False, index=True)
+    parent_id = db.Column(db.Integer, db.ForeignKey('part_categories.id'),
+                          nullable=True, index=True)
+    # Hex colour used as the accent stripe on printed labels.
+    colour = db.Column(db.String(7), nullable=True)
+    sort_order = db.Column(db.Integer, nullable=False, default=0)
+    created_at = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
+
+    children = db.relationship(
+        'PartCategory',
+        backref=db.backref('parent', remote_side=[id]),
+        lazy='select',
+        order_by='PartCategory.sort_order, PartCategory.code, PartCategory.name',
+        cascade='all, delete-orphan',
+    )
+    labels = db.relationship('PartLabel', backref='category', lazy='dynamic')
+
+    def __repr__(self):
+        return f'<PartCategory {self.code} {self.name}>'
+
+    @property
+    def full_name(self):
+        """'Technic > Pins' - one level of parent is enough on a label."""
+        if self.parent:
+            return f'{self.parent.name} > {self.name}'
+        return self.name
+
+    @property
+    def display_code(self):
+        return self.code or ''
+
+    def accent_colour(self):
+        """Own colour, else the parent's, else the LIM red."""
+        if self.colour:
+            return self.colour
+        if self.parent and self.parent.colour:
+            return self.parent.colour
+        return '#d11013'
+
+    def label_count(self, recursive=True):
+        total = self.labels.count()
+        if recursive:
+            for child in self.children:
+                total += child.label_count(recursive=True)
+        return total
+
+    @staticmethod
+    def roots():
+        return (PartCategory.query
+                .filter(PartCategory.parent_id.is_(None))
+                .order_by(PartCategory.sort_order, PartCategory.code,
+                          PartCategory.name)
+                .all())
+
+    @staticmethod
+    def choices():
+        """Flat (id, indented label) list for <select> menus."""
+        out = []
+
+        def walk(node, depth):
+            prefix = '\u00a0\u00a0' * depth + ('\u21b3 ' if depth else '')
+            code = f'{node.code} ' if node.code else ''
+            out.append((node.id, f'{prefix}{code}{node.name}'))
+            for child in node.children:
+                walk(child, depth + 1)
+
+        for root in PartCategory.roots():
+            walk(root, 0)
+        return out
+
+    def descendant_ids(self):
+        """This category plus everything beneath it."""
+        ids = [self.id]
+        for child in self.children:
+            ids.extend(child.descendant_ids())
+        return ids
+
+
+class PartLabel(db.Model):
+    """One printable label for a drawer or bag."""
+
+    __tablename__ = 'part_labels'
+
+    id = db.Column(db.Integer, primary_key=True)
+
+    # What the part is
+    part_number = db.Column(db.String(32), nullable=True, index=True)
+    # Comma-separated alternates/moulds that live in the same drawer.
+    alt_part_numbers = db.Column(db.String(255), nullable=True)
+    name = db.Column(db.String(160), nullable=False)
+    # "2 x 4", "1 x 2 x 3" - kept as text because LEGO geometry is not tidy.
+    dimensions = db.Column(db.String(40), nullable=True)
+    colour_name = db.Column(db.String(60), nullable=True)
+
+    category_id = db.Column(db.Integer, db.ForeignKey('part_categories.id'),
+                            nullable=True, index=True)
+
+    # Where it lives
+    location = db.Column(db.String(80), nullable=True, index=True)
+
+    # Artwork: a local file under UPLOAD_FOLDER/parts, or a remote URL
+    # (Rebrickable CDN). Local wins when both are set.
+    image = db.Column(db.String(255), nullable=True)
+    image_url = db.Column(db.String(500), nullable=True)
+
+    notes = db.Column(db.Text, nullable=True)
+    # 'manual' or 'rebrickable'
+    source = db.Column(db.String(20), nullable=False, default='manual')
+
+    created_by_id = db.Column(db.Integer, db.ForeignKey('users.id'),
+                              nullable=True)
+    created_at = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
+    updated_at = db.Column(db.DateTime, nullable=False, default=datetime.utcnow,
+                           onupdate=datetime.utcnow)
+
+    created_by = db.relationship('User', foreign_keys=[created_by_id])
+
+    def __repr__(self):
+        return f'<PartLabel {self.part_number or "?"} {self.name}>'
+
+    def get_image(self):
+        """URL for the label artwork, or None."""
+        if self.image:
+            path = self.image.replace('\\', '/').lstrip('/')
+            return f'/static/uploads/{path}'
+        return self.image_url or None
+
+    @property
+    def all_part_numbers(self):
+        numbers = [self.part_number] if self.part_number else []
+        if self.alt_part_numbers:
+            numbers += [n.strip() for n in self.alt_part_numbers.split(',')
+                        if n.strip()]
+        return numbers
+
+    @property
+    def part_numbers_text(self):
+        return ', '.join(self.all_part_numbers)
+
+    @property
+    def display_title(self):
+        """Name with dimensions folded in, for the big line on the label."""
+        if self.dimensions and self.dimensions.lower() not in (self.name or '').lower():
+            return f'{self.name} {self.dimensions}'
+        return self.name
+
+    def to_dict(self):
+        return {
+            'id': self.id,
+            'part_number': self.part_number,
+            'alt_part_numbers': self.alt_part_numbers,
+            'name': self.name,
+            'dimensions': self.dimensions,
+            'colour_name': self.colour_name,
+            'category_id': self.category_id,
+            'category': self.category.full_name if self.category else None,
+            'location': self.location,
+            'image': self.get_image(),
+            'notes': self.notes,
+            'source': self.source,
+        }