feat: per-order-line material override — override materials for individual renders

- Add `material_override` nullable column on OrderLine (DB migration)
- Line override takes priority over OutputType override
- PATCH /orders/{id}/lines/{id} endpoint to update material_override
- Inline dropdown on each order line in the OrderDetail page
- Amber background when override is active
- Same output type, different material per line — no need to create a new output type

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/alembic/versions/42b686e71c47_add_material_override_to_order_lines.py

@@ -0,0 +1,30 @@
+"""add material_override to order_lines
+
+Revision ID: 42b686e71c47
+Revises: cfcc7ad1e7d5
+Create Date: 2026-03-14 13:30:03.046793
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '42b686e71c47'
+down_revision: Union[str, None] = 'cfcc7ad1e7d5'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('order_lines', sa.Column('material_override', sa.String(length=200), nullable=True))
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('order_lines', 'material_override')
+    # ### end Alembic commands ###

backend/app/api/routers/orders.py

@@ -96,6 +96,7 @@ def _build_line_out(line: OrderLine) -> OrderLineOut:
         render_log=line.render_log if hasattr(line, 'render_log') else None,
         render_started_at=line.render_started_at if hasattr(line, 'render_started_at') else None,
         render_completed_at=line.render_completed_at if hasattr(line, 'render_completed_at') else None,
+        material_override=getattr(line, 'material_override', None),
         notes=line.notes,
         created_at=line.created_at,
         updated_at=line.updated_at,
@@ -1096,6 +1097,42 @@ async def dispatch_single_line_render(
     return {"dispatched": True, "line_id": str(line.id)}
 
 
+class PatchLineBody(BaseModel):
+    material_override: str | None = None
+
+
+@router.patch("/{order_id}/lines/{line_id}")
+async def patch_order_line(
+    order_id: uuid.UUID,
+    line_id: uuid.UUID,
+    body: PatchLineBody,
+    user: User = Depends(require_admin_or_pm),
+    db: AsyncSession = Depends(get_db),
+):
+    """Update fields on an order line (admin/PM only)."""
+    result = await db.execute(select(Order).where(Order.id == order_id))
+    order = result.scalar_one_or_none()
+    if not order:
+        raise HTTPException(404, detail="Order not found")
+
+    line_result = await db.execute(
+        select(OrderLine).where(OrderLine.id == line_id, OrderLine.order_id == order_id)
+    )
+    line = line_result.scalar_one_or_none()
+    if not line:
+        raise HTTPException(404, detail="Order line not found")
+
+    data = body.model_dump(exclude_unset=True)
+    from sqlalchemy import update as sql_update
+    if data:
+        await db.execute(
+            sql_update(OrderLine).where(OrderLine.id == line.id).values(**data)
+        )
+        await db.commit()
+
+    return {"updated": True, "line_id": str(line.id)}
+
+
 class RejectLineBody(BaseModel):
     reason: str = ""
 

backend/app/domains/orders/models.py

@@ -150,6 +150,7 @@ class OrderLine(Base):
         ForeignKey("global_render_positions.id", ondelete="SET NULL"),
         nullable=True,
     )
+    material_override: Mapped[str | None] = mapped_column(String(200), nullable=True, default=None)
     notes: Mapped[str | None] = mapped_column(Text, nullable=True)
     tenant_id: Mapped[uuid.UUID | None] = mapped_column(
         UUID(as_uuid=True), ForeignKey("tenants.id"), nullable=True, index=True

backend/app/domains/orders/schemas.py

@@ -66,6 +66,7 @@ class OrderLineCreate(BaseModel):
     render_position_id: uuid.UUID | None = None
     global_render_position_id: uuid.UUID | None = None
     gewuenschte_bildnummer: str | None = None
+    material_override: str | None = None
     notes: str | None = None
 
 
@@ -91,6 +92,7 @@ class OrderLineOut(BaseModel):
     render_log: dict | None = None
     render_started_at: datetime | None = None
     render_completed_at: datetime | None = None
+    material_override: str | None = None
     notes: str | None
     created_at: datetime
     updated_at: datetime

backend/app/domains/pipeline/tasks/render_order_line.py

@@ -198,9 +198,11 @@ def render_order_line_task(self, order_line_id: str):
                 from app.services.material_service import resolve_material_map
                 material_map = resolve_material_map(material_map)
 
-            # Apply global material override from OutputType (e.g. x-ray mode)
+            # Apply material override: per-line override takes priority over output type override
-            if line.output_type and line.output_type.material_override:
+            _line_override = getattr(line, 'material_override', None)
-                override_mat = line.output_type.material_override
+            _ot_override = line.output_type.material_override if line.output_type else None
+            override_mat = _line_override or _ot_override
+            if override_mat:
                 # Build override map from existing material_map keys or from parsed STEP parts
                 override_keys = set()
                 if material_map:
@@ -360,7 +362,7 @@ def render_order_line_task(self, order_line_id: str):
                         usd_path=usd_render_path,
                         focal_length_mm=focal_length_mm,
                         sensor_width_mm=sensor_width_mm,
-                        material_override=line.output_type.material_override if line.output_type else None,
+                        material_override=override_mat,
                     )
                     success = True
                     render_log = {
@@ -419,7 +421,7 @@ def render_order_line_task(self, order_line_id: str):
                     rotation_z=rotation_z,
                     focal_length_mm=focal_length_mm,
                     sensor_width_mm=sensor_width_mm,
-                    material_override=line.output_type.material_override if line.output_type else None,
+                    material_override=override_mat,
                     job_id=order_line_id,
                     order_line_id=order_line_id,
                     noise_threshold=noise_threshold,

frontend/src/api/orders.ts

@@ -55,6 +55,7 @@ export interface OrderLine {
   render_log: RenderLog | null
   render_started_at: string | null
   render_completed_at: string | null
+  material_override: string | null
   notes: string | null
   created_at: string
   updated_at: string
@@ -66,6 +67,7 @@ export interface OrderLineCreate {
   render_position_id?: string | null
   global_render_position_id?: string | null
   gewuenschte_bildnummer?: string | null
+  material_override?: string | null
   notes?: string | null
 }
 
@@ -242,6 +244,14 @@ export async function dispatchLineRender(orderId: string, lineId: string) {
   return res.data
 }
 
+export async function patchOrderLine(orderId: string, lineId: string, data: { material_override?: string | null }) {
+  const res = await api.patch<{ updated: boolean; line_id: string }>(
+    `/orders/${orderId}/lines/${lineId}`,
+    data
+  )
+  return res.data
+}
+
 export async function cancelOrderRenders(orderId: string) {
   const res = await api.post<{ cancelled: number; order_status: string; errors: string[] | null }>(
     `/orders/${orderId}/cancel-renders`

frontend/src/pages/OrderDetail.tsx

@@ -12,8 +12,8 @@ import {
   XCircle, RotateCw, Info,
 } from 'lucide-react'
 import { toast } from 'sonner'
-import { getOrder, submitOrder, deleteOrder, unlinkCadFile, regenerateItemThumbnail, patchOrderItem, removeOrderLine, dispatchRenders, cancelLineRender, dispatchLineRender, cancelOrderRenders, splitMissingStep, generateLinesFromItems, downloadOrderRenders, rejectOrder, resubmitOrder, rejectOrderLine } from '../api/orders'
+import { getOrder, submitOrder, deleteOrder, unlinkCadFile, regenerateItemThumbnail, patchOrderItem, removeOrderLine, dispatchRenders, cancelLineRender, dispatchLineRender, cancelOrderRenders, splitMissingStep, generateLinesFromItems, downloadOrderRenders, rejectOrder, resubmitOrder, rejectOrderLine, patchOrderLine } from '../api/orders'
-import { checkOrderMaterials, type UnmappedMaterial } from '../api/materials'
+import { checkOrderMaterials, listMaterials, type UnmappedMaterial, type Material } from '../api/materials'
 import UnmappedMaterialsDialog from '../components/orders/UnmappedMaterialsDialog'
 import type { OrderItem, OrderLine } from '../api/orders'
 import { listOutputTypes } from '../api/outputTypes'
@@ -903,6 +903,18 @@ function OrderLineRow({
     onError: (e: any) => toast.error(e.response?.data?.detail || 'Reject failed'),
   })
 
+  const { data: allMats } = useQuery({ queryKey: ['materials'], queryFn: listMaterials })
+  const libMats = (allMats ?? []).filter((m: Material) => m.schaeffler_code !== null).sort((a: Material, b: Material) => a.name.localeCompare(b.name))
+
+  const overrideMut = useMutation({
+    mutationFn: (val: string | null) => patchOrderLine(orderId, line.id, { material_override: val }),
+    onSuccess: () => {
+      toast.success(line.material_override ? 'Material override updated' : 'Material override set')
+      qc.invalidateQueries({ queryKey: ['order', orderId] })
+    },
+    onError: (e: any) => toast.error(e.response?.data?.detail || 'Failed to update'),
+  })
+
   const canCancel = isPrivileged && (line.render_status === 'processing' || line.render_status === 'pending') && line.output_type_id
   const canRejectLine = isPrivileged && line.item_status !== 'rejected'
 
@@ -979,6 +991,20 @@ function OrderLineRow({
               {line.render_position_name}
             </span>
           )}
+          {isPrivileged && (
+            <select
+              className="text-[10px] border border-border-default rounded px-1 py-0.5 w-full mt-1"
+              style={{ backgroundColor: line.material_override ? 'rgba(245, 158, 11, 0.1)' : 'var(--color-bg-surface)' }}
+              value={line.material_override ?? ''}
+              onChange={(e) => overrideMut.mutate(e.target.value || null)}
+              title="Material override — apply a single material to all parts for this render"
+            >
+              <option value="">No material override</option>
+              {libMats.map((m: Material) => (
+                <option key={m.id} value={m.name}>{m.name.replace('SCHAEFFLER_', '').replace(/_/g, ' ')}</option>
+              ))}
+            </select>
+          )}
         </div>
       </td>