VP bridges bound to a target printer (Proxy mode, Queue mode with
specific target) forwarded the printer's raw AMS push_status to the
slicer untouched. bambu_mqtt.py::_handle_ams_data applies a
tray_exist_bits-driven cleanup to Bambuddy's internal state
(promote empty slots to state=9, wipe stale tray_type / tray_color /
tray_info_idx / tag_uid / tray_uuid / remain) so the AMS card renders
empty slots as Empty, but the VP bridge cache never ran the same
cleanup. Net result on real hardware: a printer with 3 loaded
filaments and several previously-loaded-now-empty slots had Bambuddy's
AMS card render those slots correctly as Empty, but BambuStudio after
Sync painted them as phantom loaded filaments with stale color and
material from before the slot went empty.
Root cause: two consumers of the same payload, only one wired to the
cleanup. _handle_ams_data ran it on every push; mqtt_bridge.py::
_on_printer_raw merged the ams blob via _merge_ams_dict but copied
tray_exist_bits through as an opaque scalar without acting on it.
Fix: factored the bit-clear logic out of _handle_ams_data into a
module-level helper apply_tray_exist_bits(units, tray_exist_bits_str,
*, power_on_flag, log_label). Internal path replaced with a single
call. Bridge calls it after _merge_ams_dict on the merged ams dict,
before the merged state is stored as the 1 Hz cached-as-base source.
Shared shutdown guard kept on both sides: all-zero bits +
power_on_flag=False is the printer-off pattern (#765, would
propagate phantom empties on every reconnect); nonzero bits +
power-off is valid idle-printer state (#1365, X1C between prints)
and still applies. AMS-HT units (id >= 128) skipped on both sides.
Tests: new TestApplyTrayExistBitsHelper (10 cases) pins the helper
contract directly. 3 new bridge regression tests reproduce the
#1726 wire shape, the shutdown guard, and the AMS-HT skip on the
cached slicer-facing state. Existing internal-state tests for the
bit-clear logic (covers state=9 promotion, loaded-slot preserve,
genuine-removal-with-power-on) continue to pass against the
refactored path.
One pre-existing bridge fixture had an inconsistent tray_exist_bits
('3' for 2 AMS units each with slot 0 loaded — bit 4 missing). The
shared cleanup exposed it; corrected to '11' (bits 0 + 4) to match
real-printer wire shape.
Reported by @needo37 with full code-level analysis including the
suggested fix shape and the BAMBUDDY_VP_DUMP_WIRE diagnostic to
verify on a live system.
maziggy
8a63fcbf57