fix(ams): don't crash on rejected multiColorBox setInfo (Issue #100)

The printer replies with state="failed" and data as a 2-element list
(["multi_color_box", [...]]) instead of the usual dict when it rejects
a manual ACE slot filament assignment (e.g. custom-RFID/third-party
material). _on_multicolor_box called data.get(...) unconditionally,
crashing with AttributeError and silently dropping the report -
including the regular slot-state update that would otherwise follow.

Add a state="failed" guard plus a defensive isinstance check, and
surface the rejection via _state["last_ams_set_error"] so the caller
of handle_api_ams_set_slot's optimistic cache update isn't left
showing a false success.

Note: this fixes the crash, not necessarily the underlying rejection
itself - the printer/ACE may still refuse assignments for material
types it doesn't recognize.

NIGHTLY_CHANGELOG.md

@@ -3,3 +3,4 @@
 - Fix: on printers with multiple daisy-chained ACE units and no toolhead buffer (e.g. Kobra S1 with 2 ACE Pro), only the first unit's 4 slots were ever shown on the dashboard or synced to OrcaSlicer — the bridge silently discarded every ACE unit after the first. All units now show up correctly (Issue #95, thanks @hoovercl for the detailed report and logs)
 - Feat: the GCode browser now supports multi-select and bulk delete — click any file's checkbox to enter select mode, use "Select All" to grab everything currently visible (respecting your active search/filter), then delete the selection with one confirmation instead of one-by-one (Issue #94, thanks @Blaim)
 - Fix: **printing via OrcaSlicer "Upload and print" failed (or fed the wrong spool) when a slot below the used filament was empty** — e.g. printing with Filament 4 while slot 3 was empty. The generated AMS slot mapping inserted a placeholder pointing at the physically empty tray, which the printer rejects. Placeholders now point at a loaded tray instead. Printing with all slots full already worked and is unchanged.
+- Fix: manually assigning a filament profile to an ACE slot could crash the MQTT callback (`'list' object has no attribute 'get'`) when the printer rejected the assignment, e.g. for custom-RFID/third-party filament. The bridge now handles the printer's failure response cleanly instead of crashing (Issue #100, thanks @Blaim)

kobrax_moonraker_bridge.py

@@ -1879,10 +1879,18 @@ class KobraXBridge:
         return activity
 
     def _on_multicolor_box(self, payload: dict):
+        if payload.get("state") == "failed":
+            log.warning(f"multiColorBox/report failed: {payload.get('data')}")
+            self._state["last_ams_set_error"] = True
+            return
         data = payload.get("data") or {}
+        if not isinstance(data, dict):
+            log.warning(f"multiColorBox/report: unexpected data shape: {data!r}")
+            return
         boxes = data.get("multi_color_box") or []
         if not boxes:
             return
+        self._state["last_ams_set_error"] = False
         self._head_tools_model = int(data.get("head_tools_model", self._head_tools_model))
         self._filament_mode = self._detect_filament_mode(boxes, self._head_tools_model)
         self._state["filament_mode"] = self._filament_mode
@@ -4037,6 +4045,7 @@ class KobraXBridge:
             return web.json_response({"error": "color must be [r,g,b]"}, status=400)
         box_id, local_slot = self._global_to_box_slot(index)
         loop = asyncio.get_event_loop()
+        self._state["last_ams_set_error"] = False
         # setInfo goes via the web/printer topic (like tempature/set). Verified via
         # Workbench-Vue mqtt_setInfo verifiziert — via slicer/printer/ wurden
         # slot changes are ignored by the printer and overwritten with the old

tests/test_multicolor_box_failed_state.py

@@ -0,0 +1,69 @@
+"""AttributeError crash on multiColorBox/report failure (Issue #100).
+
+Real KX2-Pro bug: manually assigning a filament profile to an ACE slot
+(custom-RFID / third-party filament) gets rejected by the printer. Instead of
+echoing the normal success shape, the printer replies with `state: "failed"`
+and `data` as a 2-element LIST (`["multi_color_box", [...]]`) instead of the
+usual dict (`{"multi_color_box": [...]}`). `_on_multicolor_box` called
+`data.get(...)` unconditionally, crashing with
+`AttributeError: 'list' object has no attribute 'get'` and silently dropping
+the report (including the slot-state update it would otherwise have done).
+"""
+import argparse
+import tempfile
+from unittest.mock import MagicMock
+
+from kobrax_moonraker_bridge import KobraXBridge
+
+# Exact failure payload from the Issue #100 log.
+FAILED_PAYLOAD = {
+    "state": "failed",
+    "data": ["multi_color_box", [{"filaments": {"id": 2}, "id": 0}]],
+}
+
+SUCCESS_PAYLOAD = {
+    "state": "success",
+    "data": {
+        "head_tools_model": 1,
+        "multi_color_box": [
+            {"id": -1, "slots": []},
+            {
+                "id": 0,
+                "slots": [
+                    {"index": 0, "type": "PLA", "color": [0, 156, 189], "status": 5},
+                ],
+            },
+        ],
+    },
+}
+
+
+def _bridge():
+    c = MagicMock(); c.callbacks = {}; c.connected = False
+    args = argparse.Namespace(
+        printer_ip="", mqtt_port=9883, username="", password="",
+        mode_id="20030", device_id="", host="127.0.0.1", port=7125,
+        data_dir=tempfile.mkdtemp(prefix="kxmcb-"),
+    )
+    return KobraXBridge(c, args=args)
+
+
+def test_failed_state_does_not_crash():
+    b = _bridge()
+    b._on_multicolor_box(FAILED_PAYLOAD)  # must not raise
+    assert b._state["last_ams_set_error"] is True
+
+
+def test_success_after_failure_clears_error_flag():
+    b = _bridge()
+    b._on_multicolor_box(FAILED_PAYLOAD)
+    assert b._state["last_ams_set_error"] is True
+    b._on_multicolor_box(SUCCESS_PAYLOAD)
+    assert b._state["last_ams_set_error"] is False
+
+
+def test_non_dict_data_without_failed_state_does_not_crash():
+    """Defensive guard: any future non-dict `data` shape must not crash,
+    even if the printer doesn't set state="failed" for it."""
+    b = _bridge()
+    b._on_multicolor_box({"state": "success", "data": ["multi_color_box", []]})