When I finished Phase 6 of my event-driven microservices platform, I updated the architecture decision record.

ADR-016 described a resilience layer: circuit breakers on outbound dependencies, rate limiting at the perimeter, and — the part that felt particularly clean — a self-healing DLT pipeline . Dead-lettered events wouldn't sit in a table waiting for manual triage. A scheduled reprocessor would replay them with exponential backoff. A poison-message cap would prevent one bad event from blocking the rest. Dead letters would become an automatically draining queue.

The ADR status: Accepted .

The README described it. The runbook referenced it. I committed both and moved on.

Three months later, I was writing Phase 7 SLOs and noticed a Prometheus gauge I'd added: dlt_unreprocessed . It was reading 32 .

I went to check what the scheduled reprocessor would do with those 32 events. There was no scheduled reprocessor. The table had been growing since Phase 5 failure tests. Nothing had ever drained it.…