`bmi`, `pulse`, `general`, `weight`, `blood-pressure`, and `mood`
status helpers all built their `summarizeSeries` block with
`Math.min(...series.map(...))` and `Math.max(...series.map(...))`.
The same anti-pattern hit `summarize()` in `src/lib/analytics/trends.ts`
on 2026-05-16 and crashed `/api/analytics` with
`RangeError: Maximum call stack size exceeded` once an
Apple-Health-synced PULSE series outgrew V8's ~125 000-arg ceiling;
`61107e0c` folded that one. The six insight helpers are fed bounded
windows today so they never reached the ceiling, but the spread still
allocates a transient args array on every call and the fold is both
stack-safe and cheaper.
Replace each `Math.min(...) / Math.max(...) / average(...)` triplet
with a single walk that maintains running sum / min / max. The
now-unused `average()` helper is dropped from each file. Pinned by
the existing per-helper unit tests (326 passing in
`src/lib/insights` / `src/lib/analytics` / `src/app/api/analytics`).
Marc-André Bombeck
b5060f1422