BleFieldCore and MagFieldCore had converged on the same class: same
time-aware EMA, same warm-up gate, same "deviation past a threshold is an
event" shape, differing only in constants and field names. Three copies of
the alpha derivation existed across the sensor libs.
lib/baseline.ts now owns it. Both wrappers keep their own public types
(`.rssi`, `.magnitude`) so nothing downstream changed — which is what let
all 26 existing tests pass completely unmodified against the refactor.
That was the point of doing it this way: if the tests had needed editing,
the refactor would have been changing behaviour rather than removing
duplication.
coldSpot.ts deliberately does NOT adopt this. It threads immutable state
through pure functions so a whole session's narrative can be replayed in a
test without a clock — a different and equally valid shape. Collapsing the
two would force one into a style that doesn't fit it, which is how
deduplication turns into damage.
355 frontend tests pass unchanged; i18n parity gate passes.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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