feat(ST-1112): wire story-promotion into saveTask and PATCH /api/tasks/:id

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

actions/tasks.ts

@@ -9,6 +9,7 @@ import { SessionData, sessionOptions } from '@/lib/session'
 import { productAccessFilter } from '@/lib/product-access'
 import { requireProductWriter } from '@/lib/auth'
 import { taskSchema as sharedTaskSchema, type TaskInput } from '@/lib/schemas/task'
+import { updateTaskStatusWithStoryPromotion } from '@/lib/tasks-status-update'
 
 async function getSession() {
   return getIronSession<SessionData>(await cookies(), sessionOptions)
@@ -53,19 +54,30 @@ export async function saveTask(
     if (context.taskId) {
       const existing = await prisma.task.findFirst({
         where: { id: context.taskId, story: { product: scope } },
+        select: { id: true, status: true },
       })
       if (!existing) return { ok: false, code: 403, error: 'forbidden' }
 
-      const task = await prisma.task.update({
-        where: { id: context.taskId },
-        data: {
-          title,
-          description: description ?? null,
-          implementation_plan: implementation_plan ?? null,
-          priority,
-          ...(status !== undefined ? { status } : {}),
-        },
-        select: { id: true, title: true, status: true },
+      const taskId = context.taskId
+      const statusChanged = status !== undefined && status !== existing.status
+
+      const task = await prisma.$transaction(async (tx) => {
+        const updated = await tx.task.update({
+          where: { id: taskId },
+          data: {
+            title,
+            description: description ?? null,
+            implementation_plan: implementation_plan ?? null,
+            priority,
+          },
+          select: { id: true, title: true, status: true },
+        })
+
+        if (statusChanged) {
+          const result = await updateTaskStatusWithStoryPromotion(taskId, status, tx)
+          return { id: result.task.id, title: result.task.title, status: result.task.status }
+        }
+        return updated
       })
 
       revalidatePath(`/products/${context.productId}/sprint`)
@@ -222,7 +234,7 @@ export async function updateTaskStatusAction(id: string, status: 'TO_DO' | 'IN_P
   })
   if (!task) return { error: 'Taak niet gevonden' }
 
-  await prisma.task.update({ where: { id }, data: { status } })
+  await updateTaskStatusWithStoryPromotion(id, status)
 
   // /solo bewust niet revalideren: dat zou de page soft-navigaten en de
   // open SSE-stream sluiten. De Solo Paneel-flow leunt op optimistic