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Case StudyFeaturedLast updated: September 6, 2026

SellerVai

Conversational commerce platform for online merchants in Bangladesh. A per-conversation message debouncer, hybrid product search, and a DeepSeek-powered sales agent handle customer chat across Messenger, Instagram, WhatsApp, and Telegram, backed by a merchant analytics dashboard and automated follow-up nudges.

FastAPI (Python, Async)Next.js (App Router)PostgreSQL + PGVector (RAG fallback search)FastEmbed (multilingual-e5-small)Gemini Vision API (merchant marketing-post generation)DeepSeek via LangChain (hand-rolled tool-calling agent)Meta Graph API (Messenger, Instagram, WhatsApp)Telegram Bot API
Client
SellerVai
Role
Lead Full-Stack & AI Engineer
Timeline
2025 – 2026
Stack
10 technologies
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SellerVai AI Social Commerce Salesperson & Multichannel Platform
01 / 03SellerVai AI Social Commerce Salesperson & Multichannel Platform
Omnichannel Support across WhatsApp, Messenger, Instagram & Telegram
02 / 03Omnichannel Support across WhatsApp, Messenger, Instagram & Telegram
SellerVai Merchant Subscription & Automation Packages
03 / 03SellerVai Merchant Subscription & Automation Packages
Stack
FastAPI (Python, Async)Next.js (App Router)PostgreSQL + PGVector (RAG fallback search)FastEmbed (multilingual-e5-small)Gemini Vision API (merchant marketing-post generation)DeepSeek via LangChain (hand-rolled tool-calling agent)Meta Graph API (Messenger, Instagram, WhatsApp)Telegram Bot APISQLAlchemy (Async)APScheduler (offline analysis & follow-up dispatch)
Key Features
  • Per-conversation message debouncer: an in-memory 7-second quiet-window buffer merges rapid-fire multi-message bursts into one prompt — single-process by design, with the Redis migration path already scoped in code comments for when it needs to scale past one worker
  • Gemini Vision-powered marketing content: merchants upload product photos and Gemini Vision extracts attributes to auto-draft social posts — a merchant tool, not customer-facing recognition
  • Hybrid product search: SQL ILIKE match first, with PGVector semantic search as a fallback over merchant-uploaded catalogs and documents for Banglish queries ILIKE misses
  • Deterministic intent-qualification scoring: the LLM reports only observed signals (unprompted contact info, prior delivered orders, price-only questions, hard haggling) — it never assigns the score itself — and a low score nudges the agent toward requesting advance bKash payment instead of blind COD
  • Merchant analytics suite fed by a scheduled offline conversation analyzer: conversion funnel, lost-reason analysis with estimated taka lost, demand-gap detection, and stockout cost estimation — WON outcomes are read directly from the order record, the LLM only classifies the ambiguous LOST/NO_RESPONSE cases
  • Staged follow-up nudges (1h/24h/72h) after a buying-intent signal goes quiet, with platform-aware compliance — only the first-stage nudge is allowed on Messenger under its 24-hour messaging-window policy, later stages are cancelled there automatically
  • Omnichannel webhook ingestion across Messenger, Instagram, WhatsApp, and Telegram, processed asynchronously per request
  • Order creation with per-store daily follow-up caps and instant cancellation on any customer reply, order, or opt-out
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01Problem

In Bangladeshi social commerce, customers don't use search bars or SKU codes — they send screenshots and rapid-fire Banglish texts ("ei design ta ache? dam koto?") straight to a seller's Facebook page or WhatsApp. Naive bots fire a completion per message, producing chaotic duplicate replies.

Separately, merchants had no visibility into why conversations weren't converting — a customer who asked about price and vanished looked identical, from the merchant's side, to one who was never going to buy.

02Approach

Inbound webhooks from all four channels are debounced per-conversation — a 7-second in-memory quiet window merges rapid-fire messages into one prompt before the agent sees them. Product lookups run SQL ILIKE first, falling back to PGVector semantic search over merchant-uploaded catalogs and documents when a Banglish query doesn't match literally. A hand-rolled DeepSeek tool-calling loop handles the conversation, and every order it creates carries a deterministic intent score built from signals the LLM reports but never scores itself — low-intent orders get nudged toward advance payment instead of blind COD.

Underneath the live conversation, a scheduled analyzer classifies each idle conversation for the merchant dashboard — but only the ambiguous outcomes go through an LLM; whether an order actually converted is read straight from the database, not inferred. That feeds a real insights dashboard (funnel, lost-reasons, demand gaps, stockout cost) and a staged follow-up system that nudges quiet-but-interested customers back, respecting each platform's own messaging-window rules.

03Solution

SellerVai runs as a single AI salesperson across a merchant's Messenger, Instagram, WhatsApp, and Telegram, replying with price, stock, and delivery info from an evolving product catalog and knowledge base. Merchants get a dashboard that explains why conversations are being lost, not just how many closed, and a follow-up system that re-engages the ones that went quiet without crossing platform messaging policies.

04Results

Rapid-fire message bursts get one coherent reply instead of several duplicate ones, by construction — the debouncer makes duplicate bot replies structurally impossible, not just less frequent. Merchants get lost-reason, demand-gap, and stockout-cost visibility they didn't have before, computed from real order and conversation data rather than guesswork. The follow-up system re-engages buying-intent conversations that went quiet, without violating Messenger's 24-hour messaging window.