printedparts stage 5: the ledger - restock/adjust with badge attribution

Badge resolver copied from the USB contract (SSO digits, 0<digits>BZ
PayNo wrap) with names from the employees directory and the
unknown-badge policy setting; deliberately copied rather than
cross-imported so the contract test stays green. Restock and adjust
write the ledger row and move the cached quantity in one commit -
the single-commit invariant every write path must use. Adjust
requires a reason and refuses to drive stock below zero. Detail page
gains Restock/Adjust modals. Seven tests cover minting, the
cache==ledger invariant, badge shapes, policy toggle, and auth.

tests/test_plugins/test_printedparts_ledger.py

@@ -0,0 +1,121 @@
+"""Printedparts ledger + badge tests.
+
+The invariants that make the plugin trustworthy: itemcode minting, the
+single-commit cache==ledger rule, the below-zero guard, quantity edits
+forced through the ledger, and the badge contract (SSO digits, PayNo
+wrap, unknown-badge policy).
+"""
+
+import pytest
+
+from shopdb.api import db
+from shopdb.core.models import Setting
+from plugins.printedparts.models import PrintedItem, PrintedItemTransaction
+
+
+@pytest.fixture
+def item(app, db):
+    with app.app_context():
+        row = PrintedItem(itemcode='3DP-9001', itemname='Test clip',
+                          quantityonhand=0, lowstockthreshold=5)
+        db.session.add(row)
+        db.session.commit()
+        yield row.printeditemid
+
+
+@pytest.fixture
+def directory_employee(app):
+    with app.app_context():
+        from plugins.employees.models import DirectoryEmployee
+        if not db.session.get(DirectoryEmployee, 502000001):
+            db.session.add(DirectoryEmployee(
+                sso=502000001, firstname='Pat', lastname='Printer'))
+            db.session.commit()
+    return '502000001'
+
+
+def test_create_mints_itemcode(client, auth_headers):
+    response = client.post('/api/printedparts/items', json={'itemname': 'Bracket'},
+                           headers=auth_headers)
+    assert response.status_code == 201
+    data = response.get_json()['data']
+    assert data['itemcode'] == f"3DP-{data['printeditemid']:04d}"
+    assert data['quantityonhand'] == 0
+
+
+def test_update_refuses_quantity(client, auth_headers, item):
+    response = client.put(f'/api/printedparts/items/{item}',
+                          json={'quantityonhand': 50}, headers=auth_headers)
+    assert response.status_code == 400
+
+
+def test_restock_writes_ledger_and_cache(client, auth_headers, app, item,
+                                         directory_employee):
+    response = client.post(f'/api/printedparts/items/{item}/restock',
+                           json={'quantity': 10, 'badge': directory_employee},
+                           headers=auth_headers)
+    assert response.status_code == 200
+    assert response.get_json()['data']['quantityonhand'] == 10
+    with app.app_context():
+        rows = PrintedItemTransaction.query.filter_by(printeditemid=item).all()
+        assert len(rows) == 1
+        assert rows[0].transactiontype == 'restock'
+        assert rows[0].quantitychange == 10
+        assert rows[0].employeename == 'Pat Printer'
+        cached = db.session.get(PrintedItem, item).quantityonhand
+        assert cached == sum(r.quantitychange for r in rows)
+
+
+def test_payno_badge_shape_resolves(client, auth_headers, item,
+                                    directory_employee):
+    response = client.post(f'/api/printedparts/items/{item}/restock',
+                           json={'quantity': 1,
+                                 'badge': f'0{directory_employee}BZ'},
+                           headers=auth_headers)
+    assert response.status_code == 200
+
+
+def test_adjust_requires_reason_and_floors_at_zero(client, auth_headers, item,
+                                                   directory_employee):
+    no_reason = client.post(f'/api/printedparts/items/{item}/adjust',
+                            json={'quantitychange': -1,
+                                  'badge': directory_employee},
+                            headers=auth_headers)
+    assert no_reason.status_code == 400
+
+    below_zero = client.post(f'/api/printedparts/items/{item}/adjust',
+                             json={'quantitychange': -1, 'reason': 'test',
+                                   'badge': directory_employee},
+                             headers=auth_headers)
+    assert below_zero.status_code == 400
+
+
+def test_unknown_badge_denied_then_allowed_by_policy(client, auth_headers, app,
+                                                     item):
+    denied = client.post(f'/api/printedparts/items/{item}/restock',
+                         json={'quantity': 1, 'badge': '999999999'},
+                         headers=auth_headers)
+    assert denied.status_code == 422
+
+    with app.app_context():
+        Setting.set('printedparts_unknown_badge', 'allow',
+                    valuetype='string', category='printedparts')
+        db.session.commit()
+    try:
+        allowed = client.post(f'/api/printedparts/items/{item}/restock',
+                              json={'quantity': 1, 'badge': '999999999'},
+                              headers=auth_headers)
+        assert allowed.status_code == 200
+        assert allowed.get_json()['data']['quantityonhand'] == 1
+    finally:
+        with app.app_context():
+            Setting.set('printedparts_unknown_badge', 'deny',
+                        valuetype='string', category='printedparts')
+            db.session.commit()
+
+
+def test_anonymous_cannot_mutate(client, item):
+    assert client.post('/api/printedparts/items',
+                       json={'itemname': 'X'}).status_code == 401
+    assert client.post(f'/api/printedparts/items/{item}/restock',
+                       json={'quantity': 1, 'badge': '1'}).status_code == 401