diff --git a/docs/architecture/README.md b/docs/architecture/README.md
index b08672fdac..ce266dcb63 100644
--- a/docs/architecture/README.md
+++ b/docs/architecture/README.md
@@ -329,6 +329,13 @@ If `curiosity.ts` ever appears next to `attention.ts` next to
 `creativity.ts`, the thread is lost. One engine — **accumulate, decay,
 cross, consolidate** — instantiated by configuration into each aspect.
 
+**Tolerance note:** carry a **±1 tolerance** on essentially any
+calculation over these values. The space is [-1, +1] and fuzzy by
+nature — no exact-equality checks on floats, no hard cliff-edge
+thresholds where a hair's difference flips a decision, no false
+precision. Grade boundaries softly. If two readings differ by less
+than the noise floor of living, they're the same reading.
+
 ### 9.2 Dimensions — uniform signed distances
 
 Every dimension is `{value, at}` in [-1, +1] plus a **driver** (a function