Two tightly-coupled deliverables in one drop -- a new AMS Filament Backup
status/control surface, and the #1766 fix that depends on it.
Added -- AMS Filament Backup status + control
- Parse bit 18 of top-level print.cfg into PrinterState.ams_filament_backup
on every push_status. Verified against OrcaSlicer source
(DeviceManager.cpp:4961) and a live H2D ON/OFF capture. Tri-state
(None = A1 family / pre-cfg push) preserves today's behaviour.
- Hold-timer guard (3 s) prevents stale frames from flickering the badge
back to the printer's old cfg after a user-initiated toggle.
- POST /printers/{id}/ams-backup toggle, set_ams_filament_backup() client
method calling _set_print_option("auto_switch_filament", enabled).
- GET /printers/{id}/inventory-remain endpoint exposes the same map the
dispatcher uses (internal and Spoolman modes both work uniformly).
- Small icon badge in the printer card's "Filaments" section header
(placement reads as printer-wide because the cfg bit is printer-wide,
not per-AMS). Click to toggle, success toast.
- 5 i18n keys x 11 locales for the badge UI.
Fixed -- #1766: prefer_lowest didn't pick lowest, ignored backup state
- Backend gate in _compute_ams_mapping_for_printer: coerce prefer_lowest
to False when status.ams_filament_backup is False; log the skip.
- New effectivePreferLowest(setting, backup) helper applied at every
frontend sort entry point: single-printer PrintModal, multi-printer
hook per-printer, PrinterSelector InlineMappingEditor, FilamentMapping
standalone editor (the last had NO preferLowest awareness at all
before this change).
- New preferLowestSortKey(f, inventoryByTrayId) mirrors backend's two-tier
key exactly, including the banding tie-break (regular AMS < AMS-HT <
external) so the client-side pre-compute matches the dispatch-time pick.
An earlier draft used a flat `amsId * 4 + trayId` priority which gave
external slots (ams_id = -1) a NEGATIVE priority -- caught in code
review before commit.
- Settings -> Filament -> "Prefer lowest remaining filament" gets an
explanatory note about the printer-side AMS Backup dependency, with
i18n key in all 11 locales.
