case/projects/stone-followup
02/04
Stone·Fullstack·2021 - 2022In production

Stone Follow-up

A follow-up tool that drove +20% in Stone sales built 100% TDD, 10k+ req/s at peak.

+20%
in sales
10k+
req/s at peak
250k+
interactions/month
5 devs + PO + Scrum Master
team

Field reps were losing leads from blind spots in availability and follow-up. I built the engine that orchestrated 10k+ clients and 250k+ interactions per month with competitive reassignment under the hood.

01

Problem

Coordinating leads across a field sales force in real time. Reps were losing leads from blind spots who needed callback, when, on which channel. Everything in each person's head; nothing shared, nothing timed.

02

Design

Competitive reassignment as the core mechanic: every lead carries a SLA timer; if a rep doesn't respond, the next eligible rep picks it up. Visibility everywhere who's working what, since when, on which channel.

+20%
in sales
03

Engineering

100% TDD + Clean Architecture from day one. Use-case classes read like requirements documents the squad of 5 devs onboarded fast and shipped without a QA bottleneck.

04

Operation

Backend sustaining 10k+ req/s at peak with zero downtime through high-traffic periods. 250k+ interactions per month flowing through the system. Pattern survived years after I left.

decisions & tradeoffs
  • Why a SLA timer + competitive pickup?
    Self-policing fairnessRound-robin punishes nobody; SLA + pickup punishes slowness. The timer makes responsiveness the currency fairness becomes self-policing without a manager intervening.
  • Why Node.js + TypeScript?
    Node + TSSquad was already TypeScript-fluent. Mature ecosystem for the realtime workload (event loop fits coordination work). TypeScript caught domain bugs at compile time on a system handling money.

+20% measured revenue. Became Stone's #1 engagement tool and the team's internal quality benchmark.