Restrict every data API to ops and admin

Batch writes were closed in 88eede5, but every other app's viewset still used
IsAuthenticated, which in this platform means any buyer. A buyer could rewrite a
document record, create a QC result (which moves the batch status and raises a
CAPA), and reach the write endpoints for CAPAs, certificates, ESG reports and
shipments.

- Use the one IsOpsOrAdmin from apps.compliance.permissions; drop the duplicate
  copy in apps/qc/views.py.
- Apply it to the whole viewset on shipments, qc, capa, esg, documents,
  certificates-of-analysis and regulatory-certs. The buyer portal is
  server-rendered through the ORM, so it needs none of these APIs.
- Keep the buyer chat working: AI interactions stay authenticated and scoped,
  and agent reads stay open while agent writes become ops/admin.
- Close a buyer-to-admin escalation in the users API: writes are admin-only and
  role/is_active are read-only, so a buyer can no longer PATCH their own row to
  role=admin and then pass every IsOpsOrAdmin check.

apps/ai/views.py

@@ -5,6 +5,8 @@ from rest_framework import viewsets, permissions, status
 from rest_framework.decorators import action
 from rest_framework.response import Response
 
+from apps.compliance.permissions import IsOpsOrAdmin
+
 from .models import AIInteraction, AgentConfig
 from .serializers import (
     AIInteractionSerializer, ChatRequestSerializer,
@@ -100,8 +102,17 @@ class AIInteractionViewSet(viewsets.ReadOnlyModelViewSet):
 
 class AgentConfigViewSet(viewsets.ModelViewSet):
     queryset = AgentConfig.objects.all()
+    # The buyer chat reads the agent it talks to — templates/portal/chat_embed.html
+    # fetches /api/agents/<id>/ — so reads stay open to an authenticated user,
+    # scoped by get_queryset to their own or the shared agents. Only ops/admin
+    # may create or change one.
     permission_classes = [permissions.IsAuthenticated]
 
+    def get_permissions(self):
+        if self.action in ("create", "update", "partial_update", "destroy"):
+            return [IsOpsOrAdmin()]
+        return super().get_permissions()
+
     def get_serializer_class(self):
         if self.request.user.role in ("admin", "ops") or self.request.user.is_superuser:
             return AgentConfigWriteSerializer

apps/capa/views.py

@@ -1,4 +1,7 @@
-from rest_framework import viewsets, permissions
+from rest_framework import viewsets
+
+from apps.compliance.permissions import IsOpsOrAdmin
+
 from .models import CAPARecord
 from .serializers import CAPARecordSerializer
 
@@ -6,4 +9,7 @@ from .serializers import CAPARecordSerializer
 class CAPARecordViewSet(viewsets.ModelViewSet):
     queryset = CAPARecord.objects.all()
     serializer_class = CAPARecordSerializer
-    permission_classes = [permissions.IsAuthenticated]
+    # Corrective actions are an internal ops record — the buyer portal does not
+    # read them at all, through the ORM or this API — so both read and write are
+    # closed to a buyer.
+    permission_classes = [IsOpsOrAdmin]

apps/documents/views.py

@@ -1,10 +1,13 @@
 import os
 import uuid
 from django.conf import settings
-from rest_framework import viewsets, permissions, status
+from rest_framework import viewsets, status
 from rest_framework.decorators import action
 from rest_framework.parsers import MultiPartParser, FormParser
 from rest_framework.response import Response
+
+from apps.compliance.permissions import IsOpsOrAdmin
+
 from .models import Document, CertificateOfAnalysis, RegulatoryCert
 from .serializers import DocumentSerializer, DocumentUploadSerializer, CertificateOfAnalysisSerializer, RegulatoryCertSerializer
 
@@ -12,14 +15,10 @@ from .serializers import DocumentSerializer, DocumentUploadSerializer, Certifica
 class DocumentViewSet(viewsets.ModelViewSet):
     queryset = Document.objects.all()
     serializer_class = DocumentSerializer
-    permission_classes = [permissions.IsAuthenticated]
+    # Documents and certificates are the evidence a buyer's auditor relies on.
-
+    # The buyer portal serves the buyer-visible rows through the ORM
-    def get_queryset(self):
+    # (apps/buyer/views.py), so this API needs no buyer access — read or write.
-        user = self.request.user
+    permission_classes = [IsOpsOrAdmin]
-        qs = Document.objects.all()
-        if user.role == "buyer":
-            return qs.filter(visibility__in=["buyer"])
-        return qs
 
     @action(detail=False, methods=["post"], parser_classes=[MultiPartParser, FormParser])
     def upload(self, request):
@@ -64,23 +63,16 @@ class DocumentViewSet(viewsets.ModelViewSet):
 class CertificateOfAnalysisViewSet(viewsets.ModelViewSet):
     queryset = CertificateOfAnalysis.objects.select_related("batch", "qc_result").all()
     serializer_class = CertificateOfAnalysisSerializer
-    permission_classes = [permissions.IsAuthenticated]
+    # A certificate is released to buyers through the ORM (apps/buyer/views.py),
-
+    # not this API, so the API needs no buyer access. Only a published
-    def get_queryset(self):
+    # certificate is buyer-visible at all, and only ops/admin may publish one.
-        user = self.request.user
+    permission_classes = [IsOpsOrAdmin]
-        qs = CertificateOfAnalysis.objects.select_related("batch", "qc_result").all()
-        if user.role == "buyer":
-            return qs.filter(status=CertificateOfAnalysis.Status.PUBLISHED)
-        return qs
 
     @action(detail=True, methods=["post"])
     def approve(self, request, pk=None):
         """Commercial release approval: publishes the CoA and exposes it to buyers."""
         from apps.compliance.services import publish_coa
-        from apps.compliance.permissions import IsOpsOrAdmin
 
-        if not IsOpsOrAdmin().has_permission(request, self):
-            return Response({"detail": "Not permitted"}, status=status.HTTP_403_FORBIDDEN)
         coa = self.get_object()
         if coa.status != CertificateOfAnalysis.Status.PENDING_APPROVAL:
             return Response({"detail": "CoA is not pending approval"}, status=status.HTTP_400_BAD_REQUEST)
@@ -89,11 +81,8 @@ class CertificateOfAnalysisViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=["post"])
     def supersede(self, request, pk=None):
-        from apps.compliance.permissions import IsOpsOrAdmin
         from django.utils import timezone
 
-        if not IsOpsOrAdmin().has_permission(request, self):
-            return Response({"detail": "Not permitted"}, status=status.HTTP_403_FORBIDDEN)
         coa = self.get_object()
         replacement_id = request.data.get("replacement_id")
         if not replacement_id:
@@ -111,4 +100,6 @@ class CertificateOfAnalysisViewSet(viewsets.ModelViewSet):
 class RegulatoryCertViewSet(viewsets.ModelViewSet):
     queryset = RegulatoryCert.objects.all()
     serializer_class = RegulatoryCertSerializer
-    permission_classes = [permissions.IsAuthenticated]
+    # Regulatory certificates are an internal compliance record; the buyer portal
+    # does not read them, so the API is ops/admin only.
+    permission_classes = [IsOpsOrAdmin]

apps/esg/views.py

@@ -1,4 +1,7 @@
-from rest_framework import viewsets, permissions
+from rest_framework import viewsets
+
+from apps.compliance.permissions import IsOpsOrAdmin
+
 from .models import ESGFieldReport
 from .serializers import ESGFieldReportSerializer
 
@@ -6,4 +9,7 @@ from .serializers import ESGFieldReportSerializer
 class ESGFieldReportViewSet(viewsets.ModelViewSet):
     queryset = ESGFieldReport.objects.all()
     serializer_class = ESGFieldReportSerializer
-    permission_classes = [permissions.IsAuthenticated]
+    # The buyer portal reads ESG reports through the ORM
+    # (apps/buyer/views.py::BatchDetailView), not this API, so the API needs no
+    # buyer read and is closed to one.
+    permission_classes = [IsOpsOrAdmin]

apps/qc/views.py

@@ -1,22 +1,22 @@
 from django.utils import timezone
-from rest_framework import viewsets, permissions, status
+from rest_framework import viewsets, status
 from rest_framework.decorators import action
 from rest_framework.response import Response
 
-from .models import QCResult
+from apps.compliance.permissions import IsOpsOrAdmin
-from .serializers import QCResultSerializer, QCResultCreateSerializer
 from apps.compliance.services import create_coa_for_qc
 
-
+from .models import QCResult
-class IsOpsOrAdmin(permissions.BasePermission):
+from .serializers import QCResultSerializer, QCResultCreateSerializer
-    def has_permission(self, request, view):
-        user = request.user
-        return bool(user and user.is_authenticated and (user.role in ("ops", "admin") or user.is_superuser))
 
 
 class QCResultViewSet(viewsets.ModelViewSet):
     queryset = QCResult.objects.all()
-    permission_classes = [permissions.IsAuthenticated]
+    # Recording a QC result moves the batch's status, quarantines a failure and
+    # can raise a CAPA, so the whole viewset — read and write — is ops/admin
+    # only. The buyer portal reads QC results through the ORM
+    # (apps/buyer/views.py), not this API.
+    permission_classes = [IsOpsOrAdmin]
 
     def get_serializer_class(self):
         if self.action == "create":
@@ -26,7 +26,7 @@ class QCResultViewSet(viewsets.ModelViewSet):
     def perform_create(self, serializer):
         serializer.save()
 
-    @action(detail=True, methods=["post"], permission_classes=[IsOpsOrAdmin])
+    @action(detail=True, methods=["post"])
     def verify(self, request, pk=None):
         """Four-eyes quality approval. A separate authorised user validates the
         entered result. The submitter cannot approve their own result."""

apps/shipments/views.py

@@ -1,4 +1,7 @@
-from rest_framework import viewsets, permissions
+from rest_framework import viewsets
+
+from apps.compliance.permissions import IsOpsOrAdmin
+
 from .models import Shipment
 from .serializers import ShipmentSerializer
 
@@ -6,4 +9,8 @@ from .serializers import ShipmentSerializer
 class ShipmentViewSet(viewsets.ModelViewSet):
     queryset = Shipment.objects.all()
     serializer_class = ShipmentSerializer
-    permission_classes = [permissions.IsAuthenticated]
+    # The buyer portal reads shipments through the ORM (apps/buyer/views.py), not
+    # this API, so nothing outside ops/admin needs it — including for reads. A
+    # buyer must not be able to create a shipment or rewrite the status its own
+    # page displays.
+    permission_classes = [IsOpsOrAdmin]

apps/users/serializers.py

@@ -6,7 +6,10 @@ class UserSerializer(serializers.ModelSerializer):
     class Meta:
         model = User
         fields = ["id", "email", "full_name", "company_name", "role", "is_active", "created_at"]
-        read_only_fields = ["id", "created_at"]
+        # Role and is_active are never set through this API: a writable role is
+        # how a buyer could promote themselves to admin. They are changed in the
+        # administration area instead.
+        read_only_fields = ["id", "created_at", "role", "is_active"]
 
 
 class UserDetailSerializer(serializers.ModelSerializer):

apps/users/views.py

@@ -1,4 +1,7 @@
 from rest_framework import viewsets, mixins, permissions
+
+from apps.compliance.permissions import IsAdmin
+
 from .models import User
 from .serializers import UserSerializer, UserDetailSerializer, UserCreateSerializer
 
@@ -9,8 +12,18 @@ class UserViewSet(mixins.ListModelMixin,
                   viewsets.GenericViewSet):
     queryset = User.objects.all()
     serializer_class = UserSerializer
+    # A signed-in user may read their own record (get_queryset scopes a
+    # non-admin to it) but must not be able to write one. Without this, a buyer
+    # could PATCH their own row and set role to "admin", which would then pass
+    # every IsOpsOrAdmin check on the platform. Role and is_active are read-only
+    # in the serializer as well, so no API caller can change them.
     permission_classes = [permissions.IsAuthenticated]
 
+    def get_permissions(self):
+        if self.action in ("create", "update", "partial_update", "destroy"):
+            return [IsAdmin()]
+        return super().get_permissions()
+
     def get_serializer_class(self):
         if self.action == "retrieve":
             return UserDetailSerializer