The live Nextcloud 31→34 climb left 4.4 GB of images behind — one per
rung, each ~1.5 GB, all still present after it finished. On a small VPS
that is the difference between working and full.
`system reclaim` cannot help: it collects DANGLING images, and every rung
is a real tag, so all of them stay tagged and stay on disk. (Rolling apps
never hit this — moving a floating tag orphans the old image, which
reclaim then collects. It is specific to laddering.)
After a SUCCESSFUL climb only, remove the images stepped through, keeping
the immediately-previous version so a roll-back needs no download.
CFG_UPDATER_UPGRADE_PRUNE=false keeps everything. Never runs on failure,
where the older images are exactly what recovery may need.
Tested: a 3-rung climb removes 31 and 32 and keeps 33; a single-step
climb removes nothing (its previous version IS the rollback target); the
config switch disables it.
Found by looking at the box after the first real ladder run — the feature
worked, and then quietly cost 4.4 GB.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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