diff --git a/.changeset/shiny-avocados-give.md b/.changeset/shiny-avocados-give.md
new file mode 100644
index 0000000000..50baebfb52
--- /dev/null
+++ b/.changeset/shiny-avocados-give.md
@@ -0,0 +1,8 @@
+---
+"@medusajs/core-flows": patch
+"@medusajs/medusa": patch
+"@medusajs/types": patch
+"@medusajs/utils": patch
+---
+
+feat(core-flows,medusa,types,utils): adds update cart API with promotions
diff --git a/integration-tests/plugins/__tests__/cart/store/carts.spec.ts b/integration-tests/plugins/__tests__/cart/store/carts.spec.ts
index eb56343cdd..fe077a33ff 100644
--- a/integration-tests/plugins/__tests__/cart/store/carts.spec.ts
+++ b/integration-tests/plugins/__tests__/cart/store/carts.spec.ts
@@ -4,9 +4,11 @@ import {
   ICustomerModuleService,
   IPricingModuleService,
   IProductModuleService,
+  IPromotionModuleService,
   IRegionModuleService,
   ISalesChannelModuleService,
 } from "@medusajs/types"
+import { PromotionRuleOperator, PromotionType } from "@medusajs/utils"
 import path from "path"
 import { startBootstrapApp } from "../../../../environment-helpers/bootstrap-app"
 import { useApi } from "../../../../environment-helpers/use-api"
@@ -30,6 +32,7 @@ describe("Store Carts API", () => {
   let productModule: IProductModuleService
   let pricingModule: IPricingModuleService
   let remoteLink
+  let promotionModule: IPromotionModuleService
 
   let defaultRegion
 
@@ -45,6 +48,7 @@ describe("Store Carts API", () => {
     productModule = appContainer.resolve(ModuleRegistrationName.PRODUCT)
     pricingModule = appContainer.resolve(ModuleRegistrationName.PRICING)
     remoteLink = appContainer.resolve("remoteLink")
+    promotionModule = appContainer.resolve(ModuleRegistrationName.PROMOTION)
   })
 
   afterAll(async () => {
@@ -288,6 +292,171 @@ describe("Store Carts API", () => {
     })
   })
 
+  describe("POST /store/carts/:id", () => {
+    it("should update a cart with promo codes with a replace action", async () => {
+      const targetRules = [
+        {
+          attribute: "product_id",
+          operator: PromotionRuleOperator.IN,
+          values: ["prod_tshirt"],
+        },
+      ]
+
+      const appliedPromotion = await promotionModule.create({
+        code: "PROMOTION_APPLIED",
+        type: PromotionType.STANDARD,
+        application_method: {
+          type: "fixed",
+          target_type: "items",
+          allocation: "each",
+          value: "300",
+          apply_to_quantity: 1,
+          max_quantity: 1,
+          target_rules: targetRules,
+        },
+      })
+
+      const createdPromotion = await promotionModule.create({
+        code: "PROMOTION_TEST",
+        type: PromotionType.STANDARD,
+        application_method: {
+          type: "fixed",
+          target_type: "items",
+          allocation: "across",
+          value: "1000",
+          apply_to_quantity: 1,
+          target_rules: targetRules,
+        },
+      })
+
+      const cart = await cartModuleService.create({
+        currency_code: "usd",
+        email: "tony@stark.com",
+        items: [
+          {
+            id: "item-1",
+            unit_price: 2000,
+            quantity: 1,
+            title: "Test item",
+            product_id: "prod_tshirt",
+          } as any,
+        ],
+      })
+
+      const [adjustment] = await cartModuleService.addLineItemAdjustments([
+        {
+          code: appliedPromotion.code!,
+          amount: 300,
+          item_id: "item-1",
+          promotion_id: appliedPromotion.id,
+        },
+      ])
+
+      const api = useApi() as any
+
+      // Should remove earlier adjustments from other promocodes
+      let updated = await api.post(`/store/carts/${cart.id}`, {
+        promo_codes: [createdPromotion.code],
+      })
+
+      expect(updated.status).toEqual(200)
+      expect(updated.data.cart).toEqual(
+        expect.objectContaining({
+          id: cart.id,
+          items: [
+            expect.objectContaining({
+              id: "item-1",
+              adjustments: [
+                expect.objectContaining({
+                  id: expect.not.stringContaining(adjustment.id),
+                  code: createdPromotion.code,
+                }),
+              ],
+            }),
+          ],
+        })
+      )
+
+      // Should remove all adjustments from other promo codes
+      updated = await api.post(`/store/carts/${cart.id}`, {
+        promo_codes: [],
+      })
+
+      expect(updated.status).toEqual(200)
+      expect(updated.data.cart).toEqual(
+        expect.objectContaining({
+          id: cart.id,
+          items: [
+            expect.objectContaining({
+              id: "item-1",
+              adjustments: [],
+            }),
+          ],
+        })
+      )
+    })
+
+    it("should update a cart's region, sales channel and customer data", async () => {
+      const region = await regionModuleService.create({
+        name: "US",
+        currency_code: "usd",
+      })
+
+      const salesChannel = await scModuleService.create({
+        name: "Webshop",
+      })
+
+      const cart = await cartModuleService.create({
+        currency_code: "eur",
+      })
+
+      const api = useApi() as any
+
+      let updated = await api.post(`/store/carts/${cart.id}`, {
+        region_id: region.id,
+        email: "tony@stark.com",
+        sales_channel_id: salesChannel.id,
+      })
+
+      expect(updated.status).toEqual(200)
+      expect(updated.data.cart).toEqual(
+        expect.objectContaining({
+          id: cart.id,
+          currency_code: "usd",
+          region: expect.objectContaining({
+            id: region.id,
+            currency_code: "usd",
+          }),
+          email: "tony@stark.com",
+          customer: expect.objectContaining({
+            email: "tony@stark.com",
+          }),
+          sales_channel_id: salesChannel.id,
+        })
+      )
+
+      updated = await api.post(`/store/carts/${cart.id}`, {
+        email: null,
+        sales_channel_id: null,
+      })
+
+      expect(updated.status).toEqual(200)
+      expect(updated.data.cart).toEqual(
+        expect.objectContaining({
+          id: cart.id,
+          currency_code: "usd",
+          email: null,
+          customer_id: null,
+          region: expect.objectContaining({
+            id: region.id,
+            currency_code: "usd",
+          }),
+          sales_channel_id: null,
+        })
+      )
+    })
+  })
+
   describe("GET /store/carts/:id", () => {
     it("should create and update a cart", async () => {
       const region = await regionModuleService.create({
diff --git a/packages/cart/src/types/cart.ts b/packages/cart/src/types/cart.ts
index 46ffcf8358..0e1721f3a6 100644
--- a/packages/cart/src/types/cart.ts
+++ b/packages/cart/src/types/cart.ts
@@ -14,11 +14,11 @@ export interface CreateCartDTO {
 
 export interface UpdateCartDTO {
   id: string
-  region_id?: string | null
+  region_id?: string
   customer_id?: string | null
   sales_channel_id?: string | null
   email?: string | null
-  currency_code?: string | null
+  currency_code?: string
   metadata?: Record<string, unknown> | null
 
   adjustments?: (CreateLineItemAdjustmentDTO | UpdateLineItemAdjustmentDTO)[]
diff --git a/packages/core-flows/src/definition/cart/steps/find-or-create-customer.ts b/packages/core-flows/src/definition/cart/steps/find-or-create-customer.ts
index 3ccc4ebbde..40db236869 100644
--- a/packages/core-flows/src/definition/cart/steps/find-or-create-customer.ts
+++ b/packages/core-flows/src/definition/cart/steps/find-or-create-customer.ts
@@ -4,13 +4,13 @@ import { validateEmail } from "@medusajs/utils"
 import { StepResponse, createStep } from "@medusajs/workflows-sdk"
 
 interface StepInput {
-  customerId?: string
-  email?: string
+  customerId?: string | null
+  email?: string | null
 }
 
 interface StepOutput {
-  customer?: CustomerDTO
-  email?: string
+  customer?: CustomerDTO | null
+  email?: string | null
 }
 
 interface StepCompensateInput {
@@ -22,11 +22,27 @@ export const findOrCreateCustomerStepId = "find-or-create-customer"
 export const findOrCreateCustomerStep = createStep(
   findOrCreateCustomerStepId,
   async (data: StepInput, { container }) => {
+    if (
+      typeof data.customerId === undefined &&
+      typeof data.email === undefined
+    ) {
+      return new StepResponse(
+        {
+          customer: undefined,
+          email: undefined,
+        },
+        { customerWasCreated: false }
+      )
+    }
+
     const service = container.resolve<ICustomerModuleService>(
       ModuleRegistrationName.CUSTOMER
     )
 
-    const customerData: StepOutput = {}
+    const customerData: StepOutput = {
+      customer: null,
+      email: null,
+    }
     let customerWasCreated = false
 
     if (data.customerId) {
diff --git a/packages/core-flows/src/definition/cart/steps/find-sales-channel.ts b/packages/core-flows/src/definition/cart/steps/find-sales-channel.ts
index 5dcc9f60b2..bc78528b62 100644
--- a/packages/core-flows/src/definition/cart/steps/find-sales-channel.ts
+++ b/packages/core-flows/src/definition/cart/steps/find-sales-channel.ts
@@ -4,7 +4,7 @@ import { MedusaError } from "@medusajs/utils"
 import { StepResponse, createStep } from "@medusajs/workflows-sdk"
 
 interface StepInput {
-  salesChannelId?: string
+  salesChannelId?: string | null
 }
 
 export const findSalesChannelStepId = "find-sales-channel"
@@ -15,6 +15,10 @@ export const findSalesChannelStep = createStep(
       ModuleRegistrationName.SALES_CHANNEL
     )
 
+    if (data.salesChannelId === null) {
+      return new StepResponse(null)
+    }
+
     let salesChannel: SalesChannelDTO | undefined
     if (data.salesChannelId) {
       salesChannel = await salesChannelService.retrieve(data.salesChannelId)
diff --git a/packages/core-flows/src/definition/cart/steps/get-actions-to-compute-from-promotions.ts b/packages/core-flows/src/definition/cart/steps/get-actions-to-compute-from-promotions.ts
index 3e16e27f23..1efbd492f8 100644
--- a/packages/core-flows/src/definition/cart/steps/get-actions-to-compute-from-promotions.ts
+++ b/packages/core-flows/src/definition/cart/steps/get-actions-to-compute-from-promotions.ts
@@ -1,12 +1,15 @@
 import { ModuleRegistrationName } from "@medusajs/modules-sdk"
 import { CartDTO, IPromotionModuleService } from "@medusajs/types"
-import { deduplicate, isString } from "@medusajs/utils"
+import { PromotionActions, deduplicate, isString } from "@medusajs/utils"
 import { StepResponse, createStep } from "@medusajs/workflows-sdk"
 
 interface StepInput {
   cart: CartDTO
-  promoCodes: string[]
-  removePromotions: boolean
+  promoCodes?: string[]
+  action:
+    | PromotionActions.ADD
+    | PromotionActions.REMOVE
+    | PromotionActions.REPLACE
 }
 
 export const getActionsToComputeFromPromotionsStepId =
@@ -18,7 +21,11 @@ export const getActionsToComputeFromPromotionsStep = createStep(
       ModuleRegistrationName.PROMOTION
     )
 
-    const { removePromotions = false, promoCodes = [], cart } = data
+    const { action = PromotionActions.ADD, promoCodes, cart } = data
+
+    if (!Array.isArray(promoCodes)) {
+      return new StepResponse([])
+    }
 
     const appliedItemPromoCodes = cart.items
       ?.map((item) => item.adjustments?.map((adjustment) => adjustment.code))
@@ -38,12 +45,16 @@ export const getActionsToComputeFromPromotionsStep = createStep(
       ...appliedShippingMethodPromoCodes,
     ])
 
-    if (removePromotions) {
+    if (action === PromotionActions.REMOVE) {
       promotionCodesToApply = promotionCodesToApply.filter(
         (code) => !promoCodes.includes(code)
       )
     }
 
+    if (action === PromotionActions.REPLACE) {
+      promotionCodesToApply = promoCodes
+    }
+
     const actionsToCompute = await promotionModuleService.computeActions(
       promotionCodesToApply,
       cart as any
diff --git a/packages/core-flows/src/definition/cart/steps/retrieve-cart.ts b/packages/core-flows/src/definition/cart/steps/retrieve-cart.ts
index fc70c4ba09..9ce4f9b368 100644
--- a/packages/core-flows/src/definition/cart/steps/retrieve-cart.ts
+++ b/packages/core-flows/src/definition/cart/steps/retrieve-cart.ts
@@ -3,7 +3,7 @@ import { CartDTO, FindConfig, ICartModuleService } from "@medusajs/types"
 import { StepResponse, createStep } from "@medusajs/workflows-sdk"
 
 interface StepInput {
-  cartId: string
+  id: string
   config: FindConfig<CartDTO>
 }
 
@@ -15,7 +15,7 @@ export const retrieveCartStep = createStep(
       ModuleRegistrationName.CART
     )
 
-    const cart = await cartModuleService.retrieve(data.cartId, data.config)
+    const cart = await cartModuleService.retrieve(data.id, data.config)
 
     // TODO: remove this when cart handles totals calculation
     cart.items = cart.items?.map((item) => {
diff --git a/packages/core-flows/src/definition/cart/steps/update-carts.ts b/packages/core-flows/src/definition/cart/steps/update-carts.ts
index 978e6d94a6..f152e62da1 100644
--- a/packages/core-flows/src/definition/cart/steps/update-carts.ts
+++ b/packages/core-flows/src/definition/cart/steps/update-carts.ts
@@ -1,61 +1,53 @@
 import { ModuleRegistrationName } from "@medusajs/modules-sdk"
 import {
-  CartDTO,
-  FilterableCartProps,
   ICartModuleService,
-  UpdateCartDataDTO,
+  UpdateCartDTO,
+  UpdateCartWorkflowInputDTO,
 } from "@medusajs/types"
 import { getSelectsAndRelationsFromObjectArray } from "@medusajs/utils"
 import { StepResponse, createStep } from "@medusajs/workflows-sdk"
 
-type UpdateCartsStepInput = {
-  selector: FilterableCartProps
-  update: UpdateCartDataDTO
-}
-
 export const updateCartsStepId = "update-carts"
 export const updateCartsStep = createStep(
   updateCartsStepId,
-  async (data: UpdateCartsStepInput, { container }) => {
-    const service = container.resolve<ICartModuleService>(
+  async (data: UpdateCartWorkflowInputDTO[], { container }) => {
+    const cartModule = container.resolve<ICartModuleService>(
       ModuleRegistrationName.CART
     )
 
-    const { selects, relations } = getSelectsAndRelationsFromObjectArray([
-      data.update,
-    ])
-
-    const prevCarts = await service.list(data.selector, {
-      select: selects,
-      relations,
-    })
-
-    const updatedCarts = await service.update(
-      data.selector as Partial<CartDTO>,
-      data.update
+    const { selects, relations } = getSelectsAndRelationsFromObjectArray(data)
+    const cartsBeforeUpdate = await cartModule.list(
+      { id: data.map((d) => d.id) },
+      { select: selects, relations }
     )
 
-    return new StepResponse(updatedCarts, prevCarts)
+    const updatedCart = await cartModule.update(data)
+
+    return new StepResponse(updatedCart, cartsBeforeUpdate)
   },
-  async (previousCarts, { container }) => {
-    if (!previousCarts?.length) {
+  async (cartsBeforeUpdate, { container }) => {
+    if (!cartsBeforeUpdate) {
       return
     }
 
-    const service = container.resolve<ICartModuleService>(
+    const cartModule = container.resolve<ICartModuleService>(
       ModuleRegistrationName.CART
     )
 
-    const toRestore = previousCarts.map((c) => ({
-      id: c.id,
-      region_id: c.region_id,
-      customer_id: c.customer_id,
-      sales_channel_id: c.sales_channel_id,
-      email: c.email,
-      currency_code: c.currency_code,
-      metadata: c.metadata,
-    }))
+    const dataToUpdate: UpdateCartDTO[] = []
 
-    await service.update(toRestore)
+    for (const cart of cartsBeforeUpdate) {
+      dataToUpdate.push({
+        id: cart.id,
+        region_id: cart.region_id,
+        customer_id: cart.customer_id,
+        sales_channel_id: cart.sales_channel_id,
+        email: cart.email,
+        currency_code: cart.currency_code,
+        metadata: cart.metadata,
+      })
+    }
+
+    await cartModule.update(dataToUpdate)
   }
 )
diff --git a/packages/core-flows/src/definition/cart/workflows/index.ts b/packages/core-flows/src/definition/cart/workflows/index.ts
index d5a918fb5d..f39530663d 100644
--- a/packages/core-flows/src/definition/cart/workflows/index.ts
+++ b/packages/core-flows/src/definition/cart/workflows/index.ts
@@ -1,4 +1,4 @@
 export * from "./add-to-cart"
 export * from "./create-carts"
+export * from "./update-cart"
 export * from "./update-cart-promotions"
-export * from "./update-carts"
diff --git a/packages/core-flows/src/definition/cart/workflows/update-cart-promotions.ts b/packages/core-flows/src/definition/cart/workflows/update-cart-promotions.ts
index c86469f5c7..dd4550e5ca 100644
--- a/packages/core-flows/src/definition/cart/workflows/update-cart-promotions.ts
+++ b/packages/core-flows/src/definition/cart/workflows/update-cart-promotions.ts
@@ -1,4 +1,5 @@
 import { CartDTO } from "@medusajs/types"
+import { PromotionActions } from "@medusajs/utils"
 import {
   WorkflowData,
   createWorkflow,
@@ -17,7 +18,10 @@ import {
 type WorkflowInput = {
   promoCodes: string[]
   cartId: string
-  removePromotions?: boolean
+  action?:
+    | PromotionActions.ADD
+    | PromotionActions.REMOVE
+    | PromotionActions.REPLACE
 }
 
 export const updateCartPromotionsWorkflowId = "update-cart-promotions"
@@ -25,7 +29,7 @@ export const updateCartPromotionsWorkflow = createWorkflow(
   updateCartPromotionsWorkflowId,
   (input: WorkflowData<WorkflowInput>): WorkflowData<CartDTO> => {
     const retrieveCartInput = {
-      cartId: input.cartId,
+      id: input.cartId,
       config: {
         relations: [
           "items",
@@ -40,7 +44,7 @@ export const updateCartPromotionsWorkflow = createWorkflow(
     const actions = getActionsToComputeFromPromotionsStep({
       cart,
       promoCodes: input.promoCodes,
-      removePromotions: input.removePromotions || false,
+      action: input.action || PromotionActions.ADD,
     })
 
     const {
diff --git a/packages/core-flows/src/definition/cart/workflows/update-cart.ts b/packages/core-flows/src/definition/cart/workflows/update-cart.ts
new file mode 100644
index 0000000000..b5ac88d851
--- /dev/null
+++ b/packages/core-flows/src/definition/cart/workflows/update-cart.ts
@@ -0,0 +1,112 @@
+import { CartDTO, UpdateCartWorkflowInputDTO } from "@medusajs/types"
+import { PromotionActions, isPresent } from "@medusajs/utils"
+import {
+  WorkflowData,
+  createWorkflow,
+  parallelize,
+  transform,
+} from "@medusajs/workflows-sdk"
+import {
+  createLineItemAdjustmentsStep,
+  createShippingMethodAdjustmentsStep,
+  findOneOrAnyRegionStep,
+  findOrCreateCustomerStep,
+  findSalesChannelStep,
+  getActionsToComputeFromPromotionsStep,
+  prepareAdjustmentsFromPromotionActionsStep,
+  removeLineItemAdjustmentsStep,
+  removeShippingMethodAdjustmentsStep,
+  retrieveCartStep,
+  updateCartsStep,
+} from "../steps"
+
+export const updateCartWorkflowId = "update-cart"
+export const updateCartWorkflow = createWorkflow(
+  updateCartWorkflowId,
+  (input: WorkflowData<UpdateCartWorkflowInputDTO>): WorkflowData<CartDTO> => {
+    const retrieveCartInput = {
+      id: input.id,
+      config: {
+        relations: [
+          "items",
+          "items.adjustments",
+          "shipping_methods",
+          "shipping_methods.adjustments",
+        ],
+      },
+    }
+
+    const [salesChannel, region, customerData] = parallelize(
+      findSalesChannelStep({
+        salesChannelId: input.sales_channel_id,
+      }),
+      findOneOrAnyRegionStep({
+        regionId: input.region_id,
+      }),
+      findOrCreateCustomerStep({
+        customerId: input.customer_id,
+        email: input.email,
+      })
+    )
+
+    const cartInput = transform(
+      { input, region, customerData, salesChannel },
+      (data) => {
+        const { promo_codes, ...updateCartData } = data.input
+        const data_ = { ...updateCartData }
+
+        if (isPresent(updateCartData.region_id)) {
+          data_.currency_code = data.region.currency_code
+          data_.region_id = data.region.id
+        }
+
+        if (
+          updateCartData.customer_id !== undefined ||
+          updateCartData.email !== undefined
+        ) {
+          data_.customer_id = data.customerData.customer?.id || null
+          data_.email =
+            data.input?.email ?? (data.customerData.customer?.email || null)
+        }
+
+        if (updateCartData.sales_channel_id !== undefined) {
+          data_.sales_channel_id = data.salesChannel?.id || null
+        }
+
+        return data_
+      }
+    )
+
+    updateCartsStep([cartInput])
+
+    const cart = retrieveCartStep(retrieveCartInput)
+    const actions = getActionsToComputeFromPromotionsStep({
+      cart,
+      promoCodes: input.promo_codes,
+      action: PromotionActions.REPLACE,
+    })
+
+    const {
+      lineItemAdjustmentsToCreate,
+      lineItemAdjustmentIdsToRemove,
+      shippingMethodAdjustmentsToCreate,
+      shippingMethodAdjustmentIdsToRemove,
+    } = prepareAdjustmentsFromPromotionActionsStep({ actions })
+
+    parallelize(
+      removeLineItemAdjustmentsStep({ lineItemAdjustmentIdsToRemove }),
+      removeShippingMethodAdjustmentsStep({
+        shippingMethodAdjustmentIdsToRemove,
+      })
+    )
+
+    parallelize(
+      createLineItemAdjustmentsStep({ lineItemAdjustmentsToCreate }),
+      createShippingMethodAdjustmentsStep({ shippingMethodAdjustmentsToCreate })
+    )
+
+    return retrieveCartStep(retrieveCartInput).config({
+      name: "retrieve-cart-result-step",
+    })
+  }
+)
diff --git a/packages/core-flows/src/definition/cart/workflows/update-carts.ts b/packages/core-flows/src/definition/cart/workflows/update-carts.ts
deleted file mode 100644
index b7f5b07a36..0000000000
--- a/packages/core-flows/src/definition/cart/workflows/update-carts.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-import {
-  CartDTO,
-  FilterableCartProps,
-  UpdateCartDataDTO,
-} from "@medusajs/types"
-import { WorkflowData, createWorkflow } from "@medusajs/workflows-sdk"
-import { updateCartsStep } from "../steps/update-carts"
-
-type WorkflowInput = {
-  selector: FilterableCartProps
-  update: UpdateCartDataDTO
-}
-
-export const updateCartsWorkflowId = "update-carts"
-export const updateCartsWorkflow = createWorkflow(
-  updateCartsWorkflowId,
-  (input: WorkflowData<WorkflowInput>): WorkflowData<CartDTO[]> => {
-    return updateCartsStep(input)
-  }
-)
diff --git a/packages/medusa/src/api-v2/store/carts/[id]/promotions/route.ts b/packages/medusa/src/api-v2/store/carts/[id]/promotions/route.ts
index 7bb51a6955..fd334b975b 100644
--- a/packages/medusa/src/api-v2/store/carts/[id]/promotions/route.ts
+++ b/packages/medusa/src/api-v2/store/carts/[id]/promotions/route.ts
@@ -1,4 +1,5 @@
 import { updateCartPromotionsWorkflow } from "@medusajs/core-flows"
+import { PromotionActions } from "@medusajs/utils"
 import { MedusaRequest, MedusaResponse } from "../../../../../types/routing"
 import { StorePostCartsCartPromotionsReq } from "../../validators"
 
@@ -10,6 +11,7 @@ export const POST = async (req: MedusaRequest, res: MedusaResponse) => {
     input: {
       promoCodes: payload.promo_codes,
       cartId: req.params.id,
+      action: PromotionActions.ADD,
     },
     throwOnError: false,
   })
@@ -29,7 +31,7 @@ export const DELETE = async (req: MedusaRequest, res: MedusaResponse) => {
     input: {
       promoCodes: payload.promo_codes,
       cartId: req.params.id,
-      removePromotions: true,
+      action: PromotionActions.REMOVE,
     },
     throwOnError: false,
   })
diff --git a/packages/medusa/src/api-v2/store/carts/[id]/route.ts b/packages/medusa/src/api-v2/store/carts/[id]/route.ts
index e392616790..dda5cf38af 100644
--- a/packages/medusa/src/api-v2/store/carts/[id]/route.ts
+++ b/packages/medusa/src/api-v2/store/carts/[id]/route.ts
@@ -1,9 +1,9 @@
-import { MedusaRequest, MedusaResponse } from "../../../../types/routing"
-
+import { updateCartWorkflow } from "@medusajs/core-flows"
 import { UpdateCartDataDTO } from "@medusajs/types"
-import { defaultStoreCartFields } from "../query-config"
 import { remoteQueryObjectFromString } from "@medusajs/utils"
-import { updateCartsWorkflow } from "@medusajs/core-flows"
+
+import { MedusaRequest, MedusaResponse } from "../../../../types/routing"
+import { defaultStoreCartFields } from "../query-config"
 
 export const GET = async (req: MedusaRequest, res: MedusaResponse) => {
   const remoteQuery = req.scope.resolve("remoteQuery")
@@ -24,15 +24,13 @@ export const POST = async (
   req: MedusaRequest<UpdateCartDataDTO>,
   res: MedusaResponse
 ) => {
-  const updateCartWorkflow = updateCartsWorkflow(req.scope)
+  const workflow = updateCartWorkflow(req.scope)
 
-  const workflowInput = {
-    selector: { id: req.params.id },
-    update: req.validatedBody,
-  }
-
-  const { result, errors } = await updateCartWorkflow.run({
-    input: workflowInput,
+  const { errors } = await workflow.run({
+    input: {
+      ...(req.validatedBody as UpdateCartDataDTO),
+      id: req.params.id,
+    },
     throwOnError: false,
   })
 
@@ -40,5 +38,16 @@ export const POST = async (
     throw errors[0].error
   }
 
-  res.status(200).json({ cart: result[0] })
+  const remoteQuery = req.scope.resolve("remoteQuery")
+
+  const query = remoteQueryObjectFromString({
+    entryPoint: "cart",
+    fields: defaultStoreCartFields,
+  })
+
+  const [updatedCart] = await remoteQuery(query, {
+    cart: { id: req.params.id },
+  })
+
+  res.status(200).json({ cart: updatedCart })
 }
diff --git a/packages/medusa/src/api-v2/store/carts/query-config.ts b/packages/medusa/src/api-v2/store/carts/query-config.ts
index 4139bcee31..3d5fb30aa6 100644
--- a/packages/medusa/src/api-v2/store/carts/query-config.ts
+++ b/packages/medusa/src/api-v2/store/carts/query-config.ts
@@ -10,8 +10,14 @@ export const defaultStoreCartFields = [
   "items.title",
   "items.quantity",
   "items.unit_price",
+  "items.adjustments.id",
+  "items.adjustments.code",
+  "items.adjustments.amount",
   "customer.id",
   "customer.email",
+  "shipping_methods.adjustments.id",
+  "shipping_methods.adjustments.code",
+  "shipping_methods.adjustments.amount",
   "shipping_address.id",
   "shipping_address.first_name",
   "shipping_address.last_name",
@@ -40,20 +46,24 @@ export const defaultStoreCartFields = [
 
 export const defaultStoreCartRelations = [
   "items",
+  "items.adjustments",
   "region",
   "customer",
   "shipping_address",
   "billing_address",
   "shipping_methods",
+  "shipping_methods.adjustments",
 ]
 
 export const allowedRelations = [
   "items",
+  "items.adjustments",
   "region",
   "customer",
   "shipping_address",
   "billing_address",
   "shipping_methods",
+  "shipping_methods.adjustments",
   "sales_channel",
 ]
 
diff --git a/packages/medusa/src/api-v2/store/carts/validators.ts b/packages/medusa/src/api-v2/store/carts/validators.ts
index 90c6e26495..041ed2f5e4 100644
--- a/packages/medusa/src/api-v2/store/carts/validators.ts
+++ b/packages/medusa/src/api-v2/store/carts/validators.ts
@@ -81,14 +81,19 @@ export class StorePostCartsCartReq {
   @IsType([AddressPayload, String])
   shipping_address?: AddressPayload | string
 
-  @IsEmail()
   @IsOptional()
+  @IsString()
   sales_channel_id?: string
 
   @IsObject()
   @IsOptional()
   metadata?: Record<string, unknown>
 
+  @IsOptional()
+  @IsArray()
+  @Type(() => String)
+  promo_codes?: string[]
+
   // @IsOptional()
   // @IsArray()
   // @ValidateNested({ each: true })
diff --git a/packages/types/src/cart/mutations.ts b/packages/types/src/cart/mutations.ts
index 0a20438f1e..6c0d00fbcb 100644
--- a/packages/types/src/cart/mutations.ts
+++ b/packages/types/src/cart/mutations.ts
@@ -41,12 +41,12 @@ export interface CreateCartDTO {
 }
 
 export interface UpdateCartDataDTO {
-  region_id?: string | null
+  region_id?: string
   customer_id?: string | null
   sales_channel_id?: string | null
 
   email?: string | null
-  currency_code?: string | null
+  currency_code?: string
 
   shipping_address_id?: string | null
   billing_address_id?: string | null
@@ -58,7 +58,7 @@ export interface UpdateCartDataDTO {
 }
 
 export interface UpdateCartDTO extends UpdateCartDataDTO {
-  id?: string
+  id: string
 }
 
 /** CART END */
@@ -176,7 +176,7 @@ export interface UpdateLineItemWithSelectorDTO {
 
 export interface UpdateCartWithSelectorDTO {
   selector: Partial<CartDTO>
-  data: UpdateCartDTO
+  data: UpdateCartDataDTO
 }
 
 export interface UpdateLineItemDTO
diff --git a/packages/types/src/cart/workflows.ts b/packages/types/src/cart/workflows.ts
index d7a808e216..174525aae6 100644
--- a/packages/types/src/cart/workflows.ts
+++ b/packages/types/src/cart/workflows.ts
@@ -65,3 +65,14 @@ export interface AddToCartWorkflowInputDTO {
   items: CreateCartCreateLineItemDTO[]
   cart: CartDTO
 }
+
+export interface UpdateCartWorkflowInputDTO {
+  id: string
+  promo_codes?: string[]
+  region_id?: string
+  customer_id?: string | null
+  sales_channel_id?: string | null
+  email?: string | null
+  currency_code?: string
+  metadata?: Record<string, unknown> | null
+}
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 3958e296eb..59efe99812 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -1,4 +1,5 @@
 export * from "./address"
+export * from "./api-key"
 export * from "./auth"
 export * from "./bundles"
 export * from "./cache"
@@ -27,10 +28,9 @@ export * from "./sales-channel"
 export * from "./search"
 export * from "./shared-context"
 export * from "./stock-location"
+export * from "./store"
 export * from "./tax"
 export * from "./totals"
 export * from "./transaction-base"
 export * from "./user"
 export * from "./workflow"
-export * from "./api-key"
-export * from "./store"
diff --git a/packages/utils/src/promotion/index.ts b/packages/utils/src/promotion/index.ts
index f3dc9d2409..453558124f 100644
--- a/packages/utils/src/promotion/index.ts
+++ b/packages/utils/src/promotion/index.ts
@@ -41,3 +41,9 @@ export enum ComputedActions {
   REMOVE_SHIPPING_METHOD_ADJUSTMENT = "removeShippingMethodAdjustment",
   CAMPAIGN_BUDGET_EXCEEDED = "campaignBudgetExceeded",
 }
+
+export enum PromotionActions {
+  ADD = "add",
+  REMOVE = "remove",
+  REPLACE = "replace",
+}