Beating 250,000 Mental Comparisons: A Cross-Domain Engineer's Entity Resolution Case Study

An operations engineer used Claude Code to build a deterministic entity-resolution tool for two overlapping business systems.

He replayed it against eight weeks of history and found it caught about 99.2% of human-detected reconciliation errors.

The tool handled a weekly 250,000-comparison task without sending source records to an LLM, keeping the process private and repeatable.

The result turned a veteran-dependent workflow into a team process with lower cognitive load and less single-person risk.