nick-doc/04 - Flows/Seller Offer Flow.md

title, tags, related_models, related_apis

title	tags	related_models	related_apis
Seller Offer Flow	flow marketplace seller offer	SellerOffer PurchaseRequest Notification	POST /api/marketplace/purchase-requests/:id/offers GET /api/marketplace/purchase-requests/:id/offers PATCH /api/marketplace/offers/:id

Last updated: 2026-05-29 — aligned with code (see Doc vs Code Audit Report)

Seller Offer Flow

A seller browses open purchase requests and submits an offer with a price, delivery time, and notes. The buyer is notified in real time and can accept (which moves the request to PRD - Request Network In-House Checkout) or reject.

Actors

• Seller — proposes an offer.
• Buyer — receives the offer in their request detail view.
• Frontend (seller) — frontend/src/sections/request/components/seller-steps/step-1-send-proposal.tsx and the seller marketplace listing under frontend/src/app/dashboard/seller/marketplace/.
• Frontend (buyer) — frontend/src/sections/request/components/buyer-steps/step-3-select-and-pay.tsx for the offer chooser.
• Backend — SellerOfferService (backend/src/services/marketplace/SellerOfferService.ts) and controller routes.
• MongoDB — selleroffers collection.
• Socket.IO — seller-offer-update and purchase-request-update events.
• Notification service — buyer notifications.

Preconditions

• Seller is authenticated, role === "seller", status === "active".
• Target purchase request exists and status is pending, received_offers, or active (SellerOfferService.ts:83-85).
• Seller does not already have an offer on this request (uniqueness enforced by SellerOfferService.createOffer).

Offer state machine

stateDiagram-v2
    [*] --> pending: createOffer()
    pending --> withdrawn: seller withdraws (only while pending)
    pending --> rejected: another offer accepted\nor buyer rejects this one
    pending --> accepted: acceptOffer()\nor payment confirmed
    accepted --> [*]
    rejected --> [*]
    withdrawn --> [*]
    pending --> expired_via_withdrawn: validUntil < now\n→ markExpiredOffersAsWithdrawn (cron)

The valid SellerOffer statuses are pending | accepted | rejected | withdrawn (SellerOfferService.ts:308). There is no active status for SellerOffer. validUntil expirations are converted to withdrawn.

Step-by-step narrative

Discovery

1. Seller opens /dashboard/seller/marketplace. The page hits GET /api/marketplace/purchase-requests?sellerId={me} and renders cards.
2. Filtering rules: only pending or received_offers requests where the seller is public-eligible or in preferredSellerIds (see visibility table in Purchase Request Flow).
3. Clicking a card navigates to /dashboard/seller/marketplace/request/{id}; the seller sees the buyer's description, attachments, address city/region (full address withheld), and existing offers if visible.

Submission

4. Seller clicks "Send proposal" — opens step-1-send-proposal.tsx. Fields:
   • Title (defaults to a derivative of the request title)
   • Description / notes
   • Price (amount + currency, default USDT)
   • Delivery time (amount + unit: hours / days / weeks)
   • Attachments (optional, via POST /api/files/upload)
   • Valid until (optional expiry)
5. Frontend POSTs POST /api/marketplace/purchase-requests/:id/offers (the purchaseRequestId is a path parameter, not a body field).
6. Backend SellerOfferService.createOffer (:51-140):
   • Uniqueness: SellerOffer.findOne({ purchaseRequestId, sellerId }) — if present, throws "شما قبلاً برای این درخواست پیشنهاد داده‌اید" (:74). Use updateOffer to amend.
   • Status guard: loads the PurchaseRequest; rejects if its status is anything other than pending, received_offers, or active.
   • Saves the offer (status: "pending" by default in the schema).
   • Re-loads with .populate('sellerId').populate('purchaseRequestId') for the response.
7. Real-time fan-out (emitOfferUpdate, :24-46): emits seller-offer-update to seller-{sellerId} so the seller's other tabs reflect the new offer instantly.
8. Status auto-progression: if this is the first offer on a pending request, the request transitions to received_offers (:107-122).
9. Buyer notification: notificationService.notifyNewOfferReceived(buyerId, requestId, requestTitle, sellerName) writes a Notification and emits to user-{buyerId}.
10. Response: 200 { offer } (populated).

Buyer review

11. Buyer's request detail page (/dashboard/buyer/requests/{id}) joins GET /api/marketplace/purchase-requests/:id/offers — SellerOfferService.getOffersByPurchaseRequest returns all offers sorted by createdAt: -1.
12. Each offer card shows seller name, avatar, rating (from Rating Flow), price, ETA, notes.
13. Buyer either negotiates (opens chat → Negotiation Flow) or accepts the offer by triggering payment.

Accept / Select Offer → Payment

14. The buyer selects an offer via POST /api/marketplace/purchase-requests/:id/select-offer. Important: this endpoint fires only a generic purchase-request-update event to the request-{requestId} room. No per-seller socket events or notifications are sent to the winning or losing sellers at this stage.
15. The buyer's "Pay this offer" button kicks off PRD - Request Network In-House Checkout with purchaseRequestId and sellerOfferId. The offer is not immediately marked accepted; payment confirmation does that atomically when the on-chain payment is confirmed.
16. On Request Network payment confirmation:
    • The selected offer's status → accepted.
    • All other offers on the same request → rejected via SellerOffer.updateMany.
    • The purchase request: status = "payment", selectedOfferId = sellerOfferId.
    • A direct chat is created (see Chat Flow).
    • Notifications: notifyOfferAccepted to the winning seller, generic rejection notifications to the others (SellerOfferService.acceptOffer does the same in the manual path).
    • Socket events notify the winner and reject/close competing offers.

Withdrawal

17. ⚠️ POST /api/marketplace/offers/:id/withdraw does NOT exist as an HTTP route. The SellerOfferService.withdrawOffer() service method exists but is dead code — it is not wired to any controller endpoint.

    The only supported HTTP way to withdraw an offer is:

    PUT /api/marketplace/offers/:id
    Body: { status: 'withdrawn' }
    

    Note also that the frontend page /dashboard/seller/marketplace/offers (a "My Offers" listing) does not exist. Withdrawal must be triggered from the individual request detail page.

    The DB filter { status: 'pending' } inside withdrawOffer means withdrawal is impossible once accepted or rejected.

Offer update — method mismatch

⚠️ Known mismatch: The frontend sends PUT /marketplace/offers/:id to update an offer, but the backend route is registered as PATCH /api/marketplace/offers/:id (marketplaceControllerRoutes.ts). Depending on whether a proxy or middleware normalises the method, one of these may fail. Verify end-to-end and align to a single method.

Sequence diagram

sequenceDiagram
    autonumber
    actor S as Seller
    actor B as Buyer
    participant FE_S as Seller frontend
    participant FE_B as Buyer frontend
    participant BE as Backend
    participant DB as MongoDB
    participant N as NotificationService
    participant IO as SocketIO

    S->>FE_S: Browse marketplace
    FE_S->>BE: GET /api/marketplace/purchase-requests
    BE-->>FE_S: filtered request list
    S->>FE_S: Open request and send offer
    FE_S->>BE: POST /api/marketplace/purchase-requests/:id/offers
    BE->>DB: Validate offer not duplicate
    BE->>DB: Validate request status
    BE->>DB: Create offer with status pending
    opt request has no offers yet
        BE->>DB: Set request status to received_offers
    end
    BE->>N: notifyNewOfferReceived
    N->>IO: emit notification to buyer
    BE->>IO: emit seller new-offer
    BE-->>FE_S: 200 { offer }
    IO-->>FE_B: notify buyer bell icon
    B->>FE_B: Open request detail
    FE_B->>BE: GET /api/marketplace/purchase-requests/:id/offers
    BE-->>FE_B: offers
    alt
        B->>FE_B: Click pay to finish selected offer
        B->>FE_B: Request Network payment confirms
    else
        B->>FE_B: Open chat to negotiate
    end

API calls

Method	Endpoint	Purpose	Notes
POST	/api/marketplace/purchase-requests/:id/offers	Create offer	purchaseRequestId is a path param
GET	/api/marketplace/purchase-requests/:id/offers	Buyer view of offers on a request
GET	/api/marketplace/offers/:id	Single offer details
PATCH	/api/marketplace/offers/:id	Update price / ETA / notes (seller, while pending)	⚠️ Frontend sends PUT; backend registers PATCH — method mismatch
POST	/api/marketplace/offers/:id/accept	Manual acceptance (when not via webhook)
GET /api/marketplace/offers/seller/:sellerId	—	Seller's own offer history	⚠️ NOT IMPLEMENTED — getOffersBySeller() service method exists but has no HTTP route
POST /api/marketplace/offers/:id/withdraw	—	Seller withdraws	⚠️ NOT IMPLEMENTED — use PATCH /api/marketplace/offers/:id with { status: 'withdrawn' } instead

Database writes

• selleroffers: insert on create; update on accept/reject/withdraw; updateMany to bulk-reject other offers when one is accepted (SellerOfferService.acceptOffer:376-388).
• purchaserequests: status moves to received_offers on first offer, then payment on successful payment, and selectedOfferId is set.
• notifications: at least one per state change.

Socket events emitted

• seller-offer-update with eventType: 'new-offer' → seller-{sellerId} (creator's other tabs).
• purchase-request-update with eventType: 'offer-updated' → request-{requestId} on edits (SellerOfferService.ts:284-288).
• purchase-request-update → request-{requestId} when buyer calls select-offer (generic room event only — no per-seller notifications or events are sent to winning or losing sellers).
• seller-offer-update with eventType: 'payment-completed' to winning seller, 'offer-rejected' to losers (emitted by the webhook handler after payment confirmation).
• new-notification → user-{buyerId} for each new offer.

Side effects

• Triggers chat creation only after payment (not on offer creation) — minimises noise from speculative offers.
• The rejectionReason field is set to "Another offer was accepted by buyer" for losers (SellerOfferService.ts:387).
• Seller statistics aggregate (getOfferStatistics, :446-475) is computed on demand for dashboards; no denormalised counter on the user document.

Error / edge cases

• Duplicate offer by same seller → 400 with localized error. Use updateOffer instead.
• Request status not open → 400 "این درخواست دیگر برای پیشنهاد باز نیست" (:84).
• Price = 0 or negative → Mongoose validator on SellerOffer.price.amount rejects (SellerOfferService.ts:55-60 logs the validation state).
• Seller withdraws an accepted offer → blocked by the { status: 'pending' } filter; returns null.
• validUntil in the past at creation → schema-level validator should reject; otherwise the next markExpiredOffersAsWithdrawn cron run flips it to withdrawn.
• Race condition: two payments to two different offers → unlikely (frontend disables payment buttons once one is chosen); even if both arrive, PaymentCoordinator and provider idempotency decide which confirmed payment wins.
• Offer for a deleted request → orphan; the webhook handler logs "Purchase request not found" and continues. Periodic cleanup should remove orphans.

[!tip] Real-time UX Sellers should socket.emit('join-seller-room', myUserId) on dashboard mount so they see seller-offer-update events instantly when the buyer accepts/rejects.

Linked flows

• Purchase Request Flow — produces the requests sellers offer on.
• Negotiation Flow — counter-offer in in_negotiation.
• PRD - Request Network In-House Checkout — locks in the accepted offer.
• Chat Flow — direct chat opened after payment.
• Notification Flow — channels for offer events.
• Rating Flow — seller's average rating displayed in the offer card.

Source files

• Backend: backend/src/services/marketplace/SellerOfferService.ts
• Backend: backend/src/services/marketplace/marketplaceController.ts
• Backend: backend/src/models/SellerOffer.ts
• Backend: backend/src/services/payment/paymentCoordinator.ts (payment-state cascade)
• Frontend: frontend/src/sections/request/components/seller-steps/step-1-send-proposal.tsx
• Frontend: frontend/src/sections/request/components/buyer-steps/step-3-select-and-pay.tsx
• Frontend: frontend/src/app/dashboard/seller/marketplace/