archives stop reporting near-zero cost (#1344)
Reporter @nicktags hit $0.01 on a 110.3g multi-color print with the
global default filament cost set to $10/kg. archive.py initial cost
calc was correct (~$1.10), then usage_tracker.on_print_complete
overwrote archive.cost with sum(r.cost for r in results) -- where
results only includes AMS trays mapped to a spool in Bambuddy's
inventory. On a multi-color print where 3 of 4 used trays had no
inventory spool, only the one tracked slot's tiny share (~1g) survived
and the archive recorded $0.01.
The overwrite logic dates to #505 (Feb 2026) and is correct for
fully-tracked single-color prints, but the multi-color slicer feature
in 0.2.4 (988c0055) made the partial-inventory state common -- users
slice + print multi-color from Bambuddy without first setting up an
inventory entry for every tray.
Cover the gap: any filament weight not represented in results gets
charged at the global default rate. For a fully-tracked print,
untracked grams = 0 and the top-up adds nothing, so the single-color
behavior is preserved. For a partial print, the missing slots are
priced at the user's documented default rate so the archive cost
reflects the whole print.
Three call sites updated to share the same logic:
- usage_tracker.py: live cost-update on print complete
- archives.py rescan_archive: per-archive manual recalc
- archives.py recalculate_all_costs: bulk recalc button
maziggy