The v1.4.39 schema scaffolding added `measurement_rollups.sum_value`
for the cumulative-metric daily totals (steps, flights, distance,
daylight, active-energy). Extends the rollup aggregator to also `SUM`
each bucket and persist the column for every (user, type,
granularity, bucket) row regardless of metric kind — spot metrics
carry the column for free because the SUM rides on the same
$queryRaw aggregate as AVG / MIN / MAX / STDDEV_POP / REGR_*.
Boot-time backfill discovery now unions in users whose existing DAY
rollup rows carry `sum_value IS NULL`. Re-folding converges those
rows because `persistRollupRows` always writes the new column on
upsert, and the union runs as one indexed pass alongside the per-
type missing-coverage discovery.
Adds `src/lib/measurements/rollup-read-cumulative.ts` with the new
`readCumulativeDaySums` / `readCumulativeDaySumsBatch` helpers
consumers use to swap off the per-type chunked findMany loop.
Helpers fall back to `mean * count` when the legacy NULL surfaces so
the chart never paints a hole during the boot-backfill convergence
window.
Audit anchor: .planning/round-v1438-perf-analysis.md §3 (cumulative
daily sums) + §5 P3.
Marc-André Bombeck
b2a5f2c410