unexpected results of as.duration() with negative periods

[unDocUMeantIt]

i was trying to sum up some positive and negative durations made from character strings via hm() and noticed odd results. i assume this is not supposed to happen, or am i getting something wrong:

> library(lubridate)

Attaching package: ‘lubridate’

The following objects are masked from ‘package:base’:

    date, intersect, setdiff, union

> x <- hm("-01:30")
> x
[1] "-1H 30M 0S"
> as.duration(x)
[1] "-1800s (~-30 minutes)"
> x <- hm("-02:30")
> x
[1] "-2H 30M 0S"
> as.duration(x)
[1] "-5400s (~-1.5 hours)"

i'm missing an hour here. this is not happening with positive periods:

> x <- hm("01:30")
> x
[1] "1H 30M 0S"
> as.duration(x)
[1] "5400s (~1.5 hours)"

i'm using lubridate version 1.9.3 with R version 4.4.3 on kubuntu 24.04.

[unDocUMeantIt]

i think this is caused by period_to_seconds() in R/periods.r:

  x@.Data +
    60 * x@minute +
    60 * 60 * x@hour +
    60 * 60 * 24 * x@day +
    60 * 60 * 24 * 365.25 / 12 * x@month +
    60 * 60 * 24 * 365.25 * x@year

in a Period object, the negativity is only defined by the hour slot. this currently makes it impossible to get a negative ten minutes by parsing hm("-00:10"), as well as correct results from period_to_seconds(), because hm("-01:15") results in -60 + 15 = -45 instead of -60 - 15 = -75.