If you have set a Multiplier other than 1 on any zone, this release changes how much that zone waters when it has rained. A dry spell waters exactly as before. Nothing else needs your attention, and no setting has to be changed.
Changed: the multiplier is the crop factor, and it now behaves like one
The zone Multiplier is documented as the crop factor Kc, and it was applied at the very end, to the calculated duration. That scaled the whole water balance rather than the crop's water use, with two consequences.
It scaled the rain along with it. A duration derived from the bucket carries the precipitation that filled it, so multiplying the duration credited only Kc times the millimetres that actually fell. With Kc below 1 that under-credits rain and over-waters. Four millimetres a day of ET0 over three days at Kc 0.5 with 6 mm of rain owes nothing, since the crop used 6 mm and 6 mm fell, but the old order asked for 3 mm.
It left the bucket draining at the full reference rate, so any threshold to irrigate at was reached about 1/Kc times too early. No factor applied afterwards can undo a decision about when to water, which is why this could not be left as a documentation fix.
ETc = ET0 * Kc is now formed before the bucket is depleted, and the duration no longer carries the factor. The reassuring part: without rain the two orders give the same answer, (ET0 * days) * Kc against (ET0 * Kc) * days. Only a period with rain changes, and the day irrigation becomes necessary.
Reported and reasoned out by @Megalos in #779, who also worked out the second effect.
Added
An irrigation threshold per zone (#815). Irrigation used to start the moment the bucket went below 0: refill the instant anything is missing. That suits a lawn and not a tree or a hedge, which want the soil to dry down and then a deep soak. Set a threshold in the Zones panel and that zone stays dry until that much water is owed, then delivers all of it in one run. It changes when a zone waters, not how much, so a longer dry spell still gets a longer run. It follows that a zone never waters below its threshold, which also rules out very short runs. The default of 0 keeps every existing zone exactly as it is. Thanks to @murphy85.
A start trigger on a fixed clock time (#807). Alongside sunrise, sunset and solar azimuth, a trigger can now be a time of day, for irrigation that has to be done by a certain hour whatever the season. With "account for duration" on it works back from that time so the run finishes then, and it handles working back across midnight: a two-hour run finishing at 00:30 starts at 22:30 the evening before. Thanks to @Megalos.
Build
The @humanfs/node advisory in the build toolchain is resolved. Build-time only; nothing reaches users and the bundle is unchanged by it.
Full Changelog: v2026.8.4...v2026.9.0