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GrainX
GrainX - Grain Marketplace Mobile App
GrainX is a cross-platform mobile marketplace connecting Australian grain farmers, buyers, and agents for direct peer-to-peer grain trading. The app enables farmers to post grain offers, buyers to place bids, and both parties to negotiate prices through counter-bids and counter-offers — all without a middleman. It features a multi-step transaction lifecycle (from sale confirmation through platform fee payment, ownership transfer, and commodity receipt), role-based dashboards with real-time stats, a live market feed with search and filtering, urgent action alerts, agent-mediated trading with commission tracking, NGR/ABN identity verification, bank account management, push notifications via OneSignal, and Firebase-powered analytics and crash reporting. The app supports three distinct user roles (Farmer, Buyer, Agent), each with tailored navigation, home screens, and workflows.
Technologies
React NativeExpo (SDK 53)TanStack React QueryZustandNativeWind (Tailwind CSS)Firebase AnalyticsFirebase CrashlyticsOneSignalGoogle Sign-InApple AuthenticationEAS Build & Update
Features
Authentication & Onboarding
- Get Started & User Type Selection: Landing screen where users select their role — Farmer, Buyer, or Agent — to begin a tailored onboarding experience
- Onboarding Walkthrough: Role-specific swipeable onboarding slides introducing key features: posting offers/bids, negotiating, and tracking transactions
- Phone OTP Authentication: Phone-based sign-up and login via SMS or WhatsApp OTP verification for secure, passwordless access
- Google Sign-In: Social authentication via Google using Firebase Auth and @react-native-google-signin for quick account creation
- Apple Sign-In: Native Apple authentication for iOS users using expo-apple-authentication for streamlined onboarding
- Agent Registration & KYC: Dedicated agent registration flow with ABN, trading name, terms acceptance, OTP verification, and KYC review process
Dashboard & Home
- Farmer Dashboard: Home screen for farmers displaying active offers, incoming bids (with "new" badge), sales count, live market bids feed, and profile completion prompt
- Buyer Dashboard: Home screen for buyers displaying active bids, incoming offers (with "new" badge), purchases count, live market offers feed, and quick-action CTA
- Agent Dashboard: Home screen for agents displaying farmer count, offers created, active bids, earnings/commission, and KYC account review status
- Urgent Actions: Priority action items surfaced on the home screen (e.g. pending payments, ownership transfers, connection requests) with a dedicated full-list view
Grain Offer Management
- Create Grain Offer: Multi-step form for farmers to create grain offers specifying grain type, variety, grade, quantity, price per MT, session, conveyance, location, port zone, delivery timeline, and payment terms with a review step before publishing
- Edit Grain Offer: Modify existing grain offer details including price, quantity, and logistics parameters with form pre-population
- Copy Grain Offer: Duplicate an existing offer to quickly create a new one with pre-filled fields, reducing repetitive data entry
- My Offers Listing: Paginated list of farmer's grain offers with infinite scroll, search, filtering by grain type/status/conveyance, sorting, and lifecycle status tracking (Active, Paused, Draft, Expired, Completed, Cancelled)
- Offer Details & Tabs: Detailed offer view with top-tab navigation showing offer specifications, active bids received, and completed sales from that offer
Grain Bid Management
- Create Grain Bid: Multi-step form for buyers to create grain bids specifying grain type, variety, grade, quantity, price per MT, session, conveyance, delivery location, and payment terms
- Edit Grain Bid: Modify existing grain bid details with form pre-population and validation
- Copy Grain Bid: Duplicate an existing bid to quickly create a new one with pre-filled fields
- My Bids Listing: Paginated list of buyer's grain bids with infinite scroll, search, filtering, sorting, and lifecycle status tracking
- Bid Details & Tabs: Detailed bid view with top-tab navigation showing bid specifications, active offers received, and completed purchases from that bid
Negotiation
- Counter Bid: Farmers can counter a buyer's bid with adjusted price and quantity, triggering a negotiation thread with configurable max counter limits
- Counter Offer: Buyers can counter a farmer's offer with adjusted price and quantity, creating a back-and-forth negotiation workflow
- Accept / Reject Bid: Farmers can accept a bid to initiate a sale, or reject it with a reason selected from a predefined list
- Accept / Reject Offer: Buyers can accept an offer to initiate a purchase, or reject it with a reason from a predefined list
- Update Grain Quantity: Dynamic quantity update alerts during negotiation showing available, accepted, incoming, and required quantities for accurate deal-making
Live Market
- Live Market Offers: Real-time feed of all active grain offers across the marketplace with search, filtering, and infinite scroll for buyers to discover opportunities
- Live Market Bids: Real-time feed of all active grain bids across the marketplace with search, filtering, and infinite scroll for farmers to discover buyer demand
- Live Market Sales / Purchases: View of completed and in-progress trades on the live market, with detailed sale/purchase information and transaction status
- Place Bid on Live Offer: Buyers can directly place a bid on any live market offer, initiating a new negotiation thread from the marketplace feed
- Place Offer on Live Bid: Farmers can directly place an offer on any live market bid, sourcing demand from buyer requests across the platform
Transaction Management
- Sale / Purchase Initialization: After negotiation acceptance, initialize the sale with bank account selection and confirmation info review before proceeding to transaction steps
- Multi-Step Transaction Tracking: Visual progress tracker guiding both parties through the complete transaction lifecycle: Confirm Sale → Sign Agreement → Reveal Counterparty → Platform Fee → Transfer Ownership / Complete Payment → Receive Payment / Receive Commodity
- Platform Fee & Transaction ID Submission: Guided platform fee payment step displaying GrainX bank account details (BSB, account number, ABN) with transaction ID submission for verification
- Sale Cancellation: Request sale cancellation with reason selection from predefined options, with status tracking for cancellation requests
- Transaction Issue Reporting: Submit issues during any transaction step with free-text description for customer support resolution
- Invoice & RCTI Download: Download invoice and RCTI (Recipient Created Tax Invoice) documents as PDFs for completed transactions
Agent System
- Agent Onboarding: Full agent registration with personal details, ABN number, trading name, terms acceptance, and OTP-verified submission with KYC review
- Farmer Onboarding by Agent: Multi-step farmer onboarding flow: select method (new or existing), enter farmer details (name, NGR, bank info, commission rate), with draft saving and review submission
- Farmer Search & Attach: Search for existing farmers by phone or email, then attach them with a per-MT commission rate to create an agent-farmer trading relationship
- Farmer Detach: Disconnect from a farmer, terminating the trading relationship and removing agent permissions
- Farmer Management: List, search, filter, and sort connected farmers with status indicators (Active, In Review, Draft, Pending), detailed farmer profiles with summary stats, offers, and trades
- Agent Grain Offer on Behalf of Farmer: Agents can create grain offers on behalf of their connected farmers, with farmer selection and commission tracking per trade
- Agent Trades & Commission Tracking: Dedicated trades tab for agents showing all farmer trades with commission per MT, total commission, and trade status
- Farmer Profile Edit Request: Agents can request edits to farmer profiles; farmers review, approve, or reject changes with a comparison view of current vs. requested data
- Agent-Farmer Connection Consent: Farmers receive connection requests from agents and can review details, approve or reject the trading authorization with acknowledgement acceptance
- Agent Connections (Farmer View): Farmers can view all connected agents, see agent details (name, ABN, trading name, contact), summary stats (offers created, trades, commission paid), and agent offers/trades
Account & Profile
- Profile Management: View and edit personal profile including avatar upload, name, email, phone, trading name, and address with profile completion percentage tracking
- Profile Edit with OTP Verification: Sensitive profile changes require OTP re-verification sent via SMS or WhatsApp for security
- Bank Account Management: Full CRUD for bank accounts: add, edit, view, delete, and set default accounts with BSB, account number, holder name, and bank details
- Social Auth Connections: Manage linked social accounts (Google, Apple) from the account settings screen
- Phone Number Addition: Add or update phone number for social-auth users who signed up without a phone, required before creating offers
- NGR Verification: Multi-step National Grower Register number verification flow (confirm identity → check information → verification code) required for grain trading compliance
- ABN Verification: Multi-step Australian Business Number verification flow for business identity confirmation, configurable via system config feature flags
Notifications & Communication
- Push Notifications (OneSignal): Real-time push notifications for bids, offers, sales, counter-negotiations, payment reminders, and transaction updates via OneSignal with deep-link navigation
- In-App Notification Center: Paginated notification list with icon-coded types (bids, sales, offers, cancellations), seen/unseen status tracking, and mark-as-seen functionality
- Notification Deep Linking: Tapping notifications navigates directly to relevant screens (offer details, bid details, sale transaction status, etc.) via a comprehensive navigation link map
Search & Discovery
- Global Search with Suggestions: Dedicated search screen with real-time autocomplete suggestions for offers, bids, and sales, plus persistent search history per section
- Advanced List Filtering: Multi-parameter filter dialogs across all listing screens supporting grain type, variety, conveyance, state, price range, quantity range, session dates, and lifecycle status
- List Sorting: Configurable sort menus on all listing screens with options like newest first, price high-to-low, quantity, and more
System & Infrastructure
- Remote System Configuration: Server-driven feature flags controlling agent system, SMS/WhatsApp delivery, social login providers, NGR/ABN verification, force updates, max counter bids/offers, platform fee, and price limits
- App Update Management: Detects new app versions via system config and prompts users with a force-update alert linking to App Store / Play Store, plus OTA updates via EAS Update
- Offline Detection & Alerts: Network connectivity monitoring using @react-native-community/netinfo with an offline alert banner and disabled actions when offline
- Firebase Analytics & Screen Tracking: Automatic screen tracking and user analytics via @react-native-firebase/analytics with user properties set on login
- Firebase Crashlytics: Crash reporting with user identification via @react-native-firebase/crashlytics for production error monitoring
- Device Registration: Registers device metadata (app version, device type, OS, model, timezone, language, ad tracking token) on login for analytics and security
- Dark & Light Theme: Automatic and manual theme switching with persistent preference storage and Android navigation bar color matching
- Pull-to-Refresh & Smart Invalidation: Pull-to-refresh on all data screens with automatic query re-invalidation when returning to a screen after a configurable idle period
- First-Time Offer Identity Flow: First-time offer creation requires identity confirmation, information check, and verification code before allowing market participation
Challenges and Decisions
1
Challenge
Three distinct user roles (Farmer, Buyer, Agent) required completely different navigation structures, home screens, tab bars, and workflows within a single app.
Decision
Implemented role-based conditional rendering using Expo Router's Tabs.Protected guards, role-specific home screens (home-farmer, home-buyer, home-agent), and a Zustand auth store that drives UI branching throughout the entire app.
Impact
Each user role gets a fully tailored experience without code duplication, while maintaining a single codebase and deployment pipeline.
2
Challenge
The multi-step transaction lifecycle (8 distinct steps from confirmation to commodity receipt) required complex state tracking and real-time updates for both buyer and seller simultaneously.
Decision
Built a visual ProgressTracker component rendering dynamic step cards based on server-driven confirmation steps, with TanStack React Query for cache invalidation and optimistic updates on each step completion.
Impact
Both parties have a clear, guided transaction flow with real-time status sync, reducing confusion and support tickets during the settlement process.
3
Challenge
The negotiation system (counter-bids/counter-offers) needed to handle complex threading, quantity validation, configurable limits, and multiple concurrent negotiations per offer/bid.
Decision
Implemented a threaded negotiation model with server-enforced max counter limits, modal-based counter forms with Zod validation and React Hook Form, and alert dialogs for accept/reject with predefined rejection reasons.
Impact
Smooth, transparent negotiation experience that prevents abuse while keeping the deal-making process flexible and fair.
4
Challenge
The agent system required a complex consent-based authorization model where agents trade on behalf of farmers, with commission tracking, profile edit requests, and connection management.
Decision
Built a full agent-farmer relationship lifecycle: registration with KYC, farmer onboarding (new + existing), consent review flows, profile edit request/approval system, and per-trade commission calculation visible to all parties.
Impact
Agents can efficiently manage multiple farmers while farmers retain full control over their accounts and authorization, building trust in the platform.
5
Challenge
Managing data freshness across 50+ API endpoints with infinite scroll pagination, search, filtering, and cross-screen invalidation was complex and error-prone.
Decision
Adopted TanStack React Query with a structured query key factory pattern, infinite query options for all paginated lists, smart stale time configuration for dropdowns, and cross-cutting invalidation on mutations using query key hierarchies.
Impact
Consistent data freshness across all screens, reduced redundant API calls, and simplified developer experience for adding new data-fetching features.
Success Metrics
Role-Based User Experiences
3 Tailored Dashboards
Transaction Lifecycle Steps
8-Step Guided Flow
API Endpoints Managed
50+ via TanStack Query
Cross-Platform Support
iOS + Android + Web