Technical Specification Example: Engineering Walkthrough

Overview

This engineering walkthrough shows how a concise technical spec keeps teams aligned from discovery to delivery. Use it as a companion to the technical specification template when you want to see a filled-in artifact instead of a blank outline.

• Project: Unified billing reconciliation service for subscriptions
• Author: Staff Engineer
• Reviewers: Product lead, security engineer, data engineer
• Status: Draft ready for review

Context & Goals

The billing team currently reconciles Stripe, Chargebee, and internal ledger events manually. Refund edge cases and asynchronous failures create mismatched balances each week. This spec proposes an event-driven reconciliation service that:

1. Normalizes incoming billing webhooks into a canonical schema
2. Reconciles transaction state between providers and the internal ledger every hour
3. Surfaces discrepancies with remediation playbooks and dashboards

Architecture Snapshot

[Provider Webhooks] -> [Normalizer Workers] -> [Reconciliation Engine]
                                        \-> [Ledger Writer]

• Normalizer Workers translate provider payloads, validate signatures, and publish sanitized events to Kafka.
• Reconciliation Engine consumes normalized events, compares them to ledger records, and logs anomalies with severity tags.
• Ledger Writer applies accepted state transitions through idempotent APIs to keep finance data consistent.

Security reviews confirmed provider secrets live in an isolated vault namespace. Metrics ship to Grafana with P95 latency and failure rate alerts.

Key Requirements

Area	Requirement
Performance	Process 10k transactions/hour with <2 minute reconciliation lag
Reliability	Automatic retries with exponential backoff; all operations idempotent
Data	Encrypt discrepancies at rest, redact PCI data before logging
Rollout	Shadow production traffic for one week before flipping write switches

Document open questions alongside mitigation ideas, then sync with the technical requirements template if you need to dive deeper into interfaces and constraints.

Implementation Plan

1. Spike integrations with sandbox credentials to validate webhook parity across providers.
2. Build normalization layer and schema validation harness.
3. Implement reconciliation engine with deterministic diffing rules.
4. Roll out shadow mode behind feature flag, monitoring latency and error ratios.
5. Enable ledger writes once alerting stays under thresholds for seven consecutive days.

This example keeps the narrative tight, highlights irreversible decisions, and leaves room for implementation detail. Pair it with Rock-n-Roll’s AI workflows to convert your notes into a developer-ready technical specification within minutes.