computeBpInTargetPct's same-calendar-day pairing fallback (for readings
whose sys/dia timestamps drift past the 5-minute session window) keyed
on toBerlinDayKey regardless of the caller's actual user. A non-Berlin
user's two same-local-evening readings straddling Berlin midnight (but
not their own midnight) were rejected as a pair, running the in-target
percentage on fewer readings than it should have — precisely the
population the cross-tz runtime guard in bp-in-target-fast-path.ts
force-routes to this same pairing fallback to protect.
Threads an optional tz through computeBpInTargetPct / collectBpPairs /
computeBpInTargetWindows (default Berlin for untouched legacy
callers), wires it through the fast-path's live fallback and the
comprehensive-insights route's own computeBpInTargetPct call — the
other caller with the user's tz already in scope.
Investigated but left the comprehensive route's resting-pulse-proxy
day-key and BP-medication-continuity day-key on their current UTC
convention: both are joined by an exact YYYY-MM-DD key against a
UTC-anchored partner (the mood rollup's bucketStart, and the
aggregator's date_trunc'd BLOOD_PRESSURE_SYS daily series). Switching
only one side to the user's tz would trade "evening readings shift a
day" for "evening readings mismatch their pairing partner" — a
different bug, not a fix. Documented in place; a real fix needs the
mood-rollup / aggregate tiers themselves to bucket per-user-tz.
Marc-André Bombeck
56a32c528e