feat: add AssetItem.purchaseOrderId (nullable FK)

src/app/api/assets/route.ts

@@ -22,12 +22,14 @@ export async function POST(request: Request): Promise<NextResponse> {
     return NextResponse.json({ error: "Request body must be a JSON object" }, { status: 400 });
   }
 
-  const { serialNumber, model, purchaseDate, warrantyEndDate } = body as Record<string, unknown>;
+  const { serialNumber, model, purchaseDate, warrantyEndDate, purchaseOrderId } =
+    body as Record<string, unknown>;
   const validation = validateCreateAssetItemInput({
     serialNumber,
     model,
     purchaseDate,
     warrantyEndDate,
+    purchaseOrderId,
   });
 
   if (!validation.ok) {

src/lib/assets.ts

@@ -11,6 +11,7 @@ export interface AssetItemRecord {
   purchase_date: string;
   warranty_end_date: string | null;
   status: AssetItemStatus;
+  purchase_order_id: string | null;
   created_at: string;
 }
 
@@ -19,6 +20,7 @@ export interface CreateAssetItemInput {
   model: string;
   purchaseDate: Date;
   warrantyEndDate?: Date;
+  purchaseOrderId?: string | null;
 }
 
 export type ValidationResult =
@@ -48,12 +50,24 @@ const createAssetItemSchema = z.object({
   model: nonEmptyString("model is required and must be a non-empty string"),
   purchaseDate: dateString("purchaseDate is required and must be a valid date string"),
   warrantyEndDate: dateString("warrantyEndDate must be a valid date string").optional(),
+  // FK to PurchaseOrder — nullable/optional, supply-side traceability (not
+  // every AssetItem goes through a formal PO). Only a UUID *format* check
+  // here, whether it references a real PurchaseOrder is left to Prisma's
+  // own FK constraint at insert time (see createAssetItem()'s P2003
+  // handling below). Mirrors src/lib/purchase-orders.ts's receivedById
+  // optional().nullable() pattern.
+  purchaseOrderId: z
+    .string({ invalid_type_error: "purchaseOrderId must be a valid UUID string" })
+    .uuid("purchaseOrderId must be a valid UUID string")
+    .optional()
+    .nullable(),
 });
 
 /**
  * Validates raw (untyped) asset-item-creation input. serialNumber/model
  * must be non-empty strings, purchaseDate must be a valid date string,
  * warrantyEndDate is optional but must be a valid date string if present.
+ * purchaseOrderId is optional/nullable but must be a valid UUID if present.
  * status is not accepted here — new assets always start "in_stock" (same
  * pattern as Request always starting "Draft"), later states are set via
  * other operations, not at creation.
@@ -63,6 +77,7 @@ export function validateCreateAssetItemInput(input: {
   model?: unknown;
   purchaseDate?: unknown;
   warrantyEndDate?: unknown;
+  purchaseOrderId?: unknown;
 }): ValidationResult {
   const result = createAssetItemSchema.safeParse(input);
   if (!result.success) {
@@ -79,6 +94,7 @@ function toRecord(row: {
   purchaseDate: Date;
   warrantyEndDate: Date | null;
   status: AssetItemStatus;
+  purchaseOrderId: string | null;
   createdAt: Date;
 }): AssetItemRecord {
   return {
@@ -88,6 +104,7 @@ function toRecord(row: {
     purchase_date: row.purchaseDate.toISOString(),
     warranty_end_date: row.warrantyEndDate ? row.warrantyEndDate.toISOString() : null,
     status: row.status,
+    purchase_order_id: row.purchaseOrderId,
     created_at: row.createdAt.toISOString(),
   };
 }
@@ -102,7 +119,10 @@ export type CreateAssetItemResult =
  * caught here and translated into the same `{ok:false,error}` shape as
  * input validation failures, rather than letting a raw Prisma error leak
  * to the API layer. Mirrors createEmployee()/createRequest()'s P2003
- * handling for FK violations.
+ * handling for FK violations. If purchaseOrderId doesn't reference an
+ * existing PurchaseOrder, Prisma raises P2003 (FK constraint violation) —
+ * caught the same way, mirrors src/lib/purchase-orders.ts's
+ * createPurchaseOrder() P2003 handling.
  */
 export async function createAssetItem(
   input: CreateAssetItemInput
@@ -114,6 +134,7 @@ export async function createAssetItem(
         model: input.model,
         purchaseDate: input.purchaseDate,
         warrantyEndDate: input.warrantyEndDate ?? null,
+        purchaseOrderId: input.purchaseOrderId ?? null,
       },
     });
     return { ok: true, value: toRecord(created) };
@@ -121,6 +142,9 @@ export async function createAssetItem(
     if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === "P2002") {
       return { ok: false, error: "serialNumber already exists" };
     }
+    if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === "P2003") {
+      return { ok: false, error: "purchaseOrderId does not reference an existing purchase order" };
+    }
     throw error;
   }
 }