The accumulated data starts predicting instead of just recording:
- Time pattern (weekday x hour density grid): WHEN the site is dangerous, on
one card - shift-change, post-lunch, Thursday-afternoon hotspots become
visible. Bucketing runs in PHP on the server-local clock (site timezone)
so the SQL stays portable (the sqlite harness has no FROM_UNIXTIME).
- Precursor-spike alert: last-7-days count of precursor signals (near-miss,
zone entries, occupancy violations - signals, not injuries) vs the prior
4-week weekly baseline. Ratio >= 1.5 with at least 5 samples raises a
banner above the KPIs: an alarm on the PRECURSOR of an accident, with a
concrete suggestion (staffing/route/rest review). Below the sample floor
it never fires - a ratio over 2 events is noise, not statistics.
- Period-over-period trends on every KPI: reportSummary gained an optional
upper bound so the identical aggregation runs over the preceding window.
Worsening turns red, improving turns accent - except the near-miss count,
which stays NEUTRAL: more near-misses may mean better detection, not more
danger, and the report must not editorialize that.
Verified: PHPUnit 140 pass (2 new: window separation + pattern bucketing,
spike ratio + sample floor) + Chrome real-render (alert banner, KPI trend
lines, Thursday-afternoon hotspot readable in the grid).
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