There appears to be something messed up in nup-headless's volume setting code that results in songs getting preloaded with the incorrect volume, which then gets adjusted as soon as the song becomes current.
In this case, 0.821 was the correct volume for 5970635633197056, but it initially used 6134788746379264's volume of 0.346:
13:31:18 Switching to /var/cache/nup/6134788746379264.mp3 (4m17.426666666s)
13:31:18 Setting volume to 0.346
...
13:33:27 Reporting play of 6134788746379264 at 2025年12月24日T13:31:18.395-07:00
...
13:35:18 Loading next song 5970635633197056 (...)
13:35:18 Set next to /var/cache/nup/5970635633197056.mp3 (4m30.863673469s)
13:35:18 Setting next volume to 0.346
13:35:35 Switching to /var/cache/nup/5970635633197056.mp3 (4m30.863673469s)
13:35:35 Setting volume to 0.821
I probably just broke this in c36d374b5f.
There appears to be something messed up in `nup-headless`'s volume setting code that results in songs getting preloaded with the incorrect volume, which then gets adjusted as soon as the song becomes current.
In this case, 0.821 was the correct volume for 5970635633197056, but it initially used 6134788746379264's volume of 0.346:
```
13:31:18 Switching to /var/cache/nup/6134788746379264.mp3 (4m17.426666666s)
13:31:18 Setting volume to 0.346
...
13:33:27 Reporting play of 6134788746379264 at 2025年12月24日T13:31:18.395-07:00
...
13:35:18 Loading next song 5970635633197056 (...)
13:35:18 Set next to /var/cache/nup/5970635633197056.mp3 (4m30.863673469s)
13:35:18 Setting next volume to 0.346
13:35:35 Switching to /var/cache/nup/5970635633197056.mp3 (4m30.863673469s)
13:35:35 Setting volume to 0.821
```
I probably just broke this in c36d374b5f95cc411ac03dfff6431579f7427abc.