Proof Pack · All families
Devon Park × Ledger · API
Ledger Sync, Made Realtime
A flaky nightly job that broke reconciliations became a typed, tested realtime sync the finance team trusts.
Ledger reconciled accounts on a nightly batch that failed silently and often. Finance found out at month end. I rebuilt it as a realtime sync with types, tests, and alerts.
Client
Ledger, fintech startup
Engagement
Backend rebuild, three weeks
Stack
TypeScript, a typed queue, and alerts
Overview
What three weeks documented
The old job was a single untyped script that failed without telling anyone. I rebuilt it as a typed, idempotent sync that processes events as they land, retries safely, and pages a human when something is actually wrong, not at 3am for nothing.
3
Week Engagement
1
Sync Rebuilt
28
Tests Written
1
Alert Runbook Delivered
The Evidence
The rebuilt sync
The new realtime sync: typed events, safe retries, and alerts that only fire when a human is actually needed.
The Build
A typed, idempotent realtime sync with retries and meaningful alerts. Correct by construction, not by hope.
What I Did Not Measure
Close-time savings sit in Ledger's own numbers, not mine. I document the build; the results stay with them.
“The nightly job that ruined month-end is gone. Reconciliations are realtime now, and we trust them.”
Finance lead, Ledger
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