Sentinel Dev Diary: How Four Dedicated Registers Replaced Scattered Dev Notes

The Sentinel project began with a fully written ten-document specification before any code was authored, but an unexpected documentation problem emerged almost immediately after coding started. Early attempts to track decisions and deferrals — first in pull request bodies, then in a single shared markdown file — proved unreliable, with information quietly falling out of view rather than being lost dramatically. The single-file approach also duplicated itself across two repositories, meaning the same organizational flaw was being repeated in parallel for one shared specification. The team's solution was a unified set of structured registers spanning both repositories, with each entry numbered immutably and never duplicated elsewhere. These registers are divided by type — requirements, components, decisions, roadmap checkpoints, assumptions, risks, open questions, and deferred work — ensuring every category has clear rules for what belongs in it.