Event-driven settlement ledger & exception console for DACH payments desk
Replaced a brittle batch-and-spreadsheet pipeline with an append-only event ledger in Temporal.io, cutting daily multi-currency reconciliation from T+2 days to < 38 minutes.
Key Production Metric & Outcome
Daily settlement reconciliation cycle reduced by 96.2%; 100% audit reconstructability across €420M+ monthly transactional volume.
A regulated payments desk in the DACH region processed high-volume cross-border corporate settlements using legacy batch scripts and shared spreadsheets. Reconciling failed SEPA payments required manual investigator intervention.
Problem
Operators had no single system view indicating which inbound MT940 / CAMT.053 settlement files had posted, which had thrown schema validation exceptions, and which were awaiting treasury authorization. Engineering was frequently paged to reconstruct ledger states from raw log files.
Architecture & Engineering Approach
We modeled financial settlement as a strictly ordered, append-only event stream:
- Temporal Workflow Orchestration: Ingestion, validation, posting, and multi-leg compensation executed as deterministic Temporal workflows with automated exponential retries.
- Strict PostgreSQL Isolation: Read-committed write paths with advisory locks preventing double-spend and concurrent reconciliation race conditions.
- Audit-Compliant Operator Console: React-based operator desk allowing treasury staff to review, annotate, and trigger compensating ledger entries with full cryptographic audit logging.
Idempotency Contracts & Byzantine Failure Invariants
Every monetary state mutation enforces cryptographic idempotency keys hashed with upstream message nonces. During simulated dual-leader database failovers and network split-brain chaos injection tests, the settlement engine proved zero unhedged accounting deltas and self-healed pending transaction trees within 1.2 seconds.