feat: 支持取消指派打手，可重新指派他人

- 后台可取消进行中订单的指派：订单回未分配，冻结押金全额退还，记录事件与审计
- 工单列表新增「取消指派」按钮（带确认弹窗），客服/管理员/运营可用
- 取消后可重新指派给其他打手

apps/backend/src/repositories/worker-platform/work-order-repo.ts

@@ -1063,6 +1063,96 @@ export async function cancelWorkerWorkOrder(input: {
   })
 }
 
+export async function unassignWorkOrder(input: {
+  workOrderId: number
+  now: string
+}): Promise<{
+  order: WorkOrderRow | null
+  failureReason: 'work_order_not_in_progress' | 'work_order_no_worker' | null
+}> {
+  return withTransaction(async (client) => {
+    const currentResult = await client.query<WorkOrderRow>(
+      `
+        SELECT *
+        FROM work_orders
+        WHERE id = $1
+        FOR UPDATE
+      `,
+      [input.workOrderId],
+    )
+    const workOrder = currentResult.rows[0] || null
+    if (!workOrder || workOrder.status !== 'in_progress') {
+      return { order: null, failureReason: 'work_order_not_in_progress' }
+    }
+    const workerId = Number(workOrder.assigned_worker_id || 0)
+    if (!workerId) {
+      return { order: null, failureReason: 'work_order_no_worker' }
+    }
+
+    await ensureWorkerWalletWithClient(client, workerId, input.now)
+    const wallet = await getWorkerWalletWithClient(client, workerId)
+    const releaseAmount = Math.min(
+      await getOutstandingDepositAmountWithClient(client, workerId, input.workOrderId),
+      Number(wallet?.frozen_deposit_amount || 0),
+    )
+
+    await client.query(
+      `
+        UPDATE work_orders
+        SET
+          status = 'unassigned',
+          assigned_worker_id = NULL,
+          assigned_at = NULL,
+          deadline_at = NULL,
+          updated_at = $1
+        WHERE id = $2
+      `,
+      [input.now, input.workOrderId],
+    )
+
+    if (releaseAmount > 0) {
+      const nextAvailable = Number(wallet?.available_amount || 0) + releaseAmount
+      const nextFrozen = Math.max(
+        0,
+        Number(wallet?.frozen_deposit_amount || 0) - releaseAmount,
+      )
+      await client.query(
+        `
+          UPDATE worker_wallets
+          SET available_amount = $1, frozen_deposit_amount = $2, updated_at = $3
+          WHERE worker_id = $4
+        `,
+        [nextAvailable, nextFrozen, input.now, workerId],
+      )
+      await client.query(
+        `
+          INSERT INTO worker_wallet_ledgers (
+            worker_id, ledger_type, amount, balance_after, frozen_after,
+            related_work_order_id, note, payload_json, created_at
+          ) VALUES ($1, 'deposit_release', $2, $3, $4, $5, '后台取消指派退还押金', '{}'::jsonb, $6)
+        `,
+        [workerId, releaseAmount, nextAvailable, nextFrozen, input.workOrderId, input.now],
+      )
+    }
+
+    await createWorkOrderEventWithClient(client, {
+      workOrderId: input.workOrderId,
+      actorType: 'admin',
+      actorId: '',
+      eventType: 'unassigned_by_admin',
+      fromStatus: 'in_progress',
+      toStatus: 'unassigned',
+      payloadJson: JSON.stringify({ workerId, releaseAmount }),
+      now: input.now,
+    })
+
+    return {
+      order: await getWorkOrderByIdWithClient(client, input.workOrderId),
+      failureReason: null,
+    }
+  })
+}
+
 export async function countWorkerCancellationsSince(
   workerId: number | string,
   sinceIso: string,

apps/backend/src/routes/admin/worker-platform.ts

@@ -3,6 +3,7 @@ import { Router } from 'express'
 import {
   acceptAdminWorkOrder,
   assignAdminWorkOrderToWorker,
+  unassignAdminWorkOrder,
   creditAdminWorkerWallet,
   createAdminMockWorkOrder,
   deductAdminWorkOrderPendingDeposit,
@@ -361,6 +362,22 @@ router.post(
   ),
 )
 
+router.post(
+  '/worker-platform/orders/:workOrderId/unassign',
+  requireAdminRoles(['admin', 'operator', 'support']),
+  createJsonHandler((req) => unassignAdminWorkOrder(String(req.params.workOrderId || '')), {
+    successMessage: '已取消指派',
+    errorMessage: '取消指派失败',
+    scope: '[admin/worker-platform/orders/:workOrderId/unassign]',
+    audit: (req, data) => ({
+      action: 'work_order_worker_unassigned',
+      targetType: 'work_order',
+      targetId: String(req.params.workOrderId || ''),
+      data: data && typeof data === 'object' ? (data as Record<string, unknown>) : {},
+    }),
+  }),
+)
+
 router.delete(
   '/worker-platform/orders/:workOrderId',
   requireAdminRoles(['admin', 'operator']),

apps/backend/src/services/worker-platform/admin-service.ts

@@ -6,6 +6,7 @@ import {
   acceptWorkOrderAndSettle,
   addWorkerWalletCredit,
   assignWorkOrderToWorker,
+  unassignWorkOrder,
   countWorkerAcceptedOrders,
   countWorkerActiveOrders,
   countWorkCategoryUsages,
@@ -1146,6 +1147,43 @@ export async function acceptAdminWorkOrder(workOrderId: number | string) {
   return { order: mapWorkOrderAdmin(updated || workOrder) }
 }
 
+export async function unassignAdminWorkOrder(workOrderId: number | string) {
+  const workOrder = await getRequiredWorkOrder(workOrderId)
+  if (
+    workOrder.status !== WORK_ORDER_STATUS.IN_PROGRESS ||
+    !workOrder.assigned_worker_id
+  ) {
+    throw createHttpError('只有进行中且已指派打手的订单可以取消指派', {
+      statusCode: 409,
+      errorCode: 'work_order_unassign_status_invalid',
+    })
+  }
+  const now = nowIso()
+  const { order: updated, failureReason } = await unassignWorkOrder({
+    workOrderId: workOrder.id,
+    now,
+  })
+  if (failureReason === 'work_order_not_in_progress') {
+    throw createHttpError('订单状态已变化，无法取消指派', {
+      statusCode: 409,
+      errorCode: 'work_order_unassign_status_invalid',
+    })
+  }
+  if (failureReason === 'work_order_no_worker') {
+    throw createHttpError('该订单未指派打手', {
+      statusCode: 409,
+      errorCode: 'work_order_unassign_no_worker',
+    })
+  }
+  if (!updated) {
+    throw createHttpError('取消指派失败，订单状态可能已变化', {
+      statusCode: 409,
+      errorCode: 'work_order_unassign_conflict',
+    })
+  }
+  return { order: mapWorkOrderAdmin(updated) }
+}
+
 export async function getAdminWorkerPlatformSummary() {
   const [pendingWorkers, pendingMaterial, openOrders, inProgressOrders] = await Promise.all([
     listWorkerUsers({ page: 1, pageSize: 1, status: 'pending_review' }),