A multi-rail exception mesh, not best-effort dedupe
A duplicate payment in production is not an edge case. It is the control plane showing you what you never modeled. A retried request can land as a final success on one rail and a settlement reject on another, look clean on the dashboard, and still move two accounts twice. Best-effort dedupe is not a control.

Lead essay
The current Doric argument leads the index ahead of the chronological archive.
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