Fix AMS auto-matching to use tray_info_idx from 3MF files

When multiple AMS trays have the same filament type and color, Bambuddy
now uses the tray_info_idx attribute from the 3MF file to identify the
exact spool selected during slicing. This ensures the correct tray is
used rather than just picking the first match.

Matching priority: tray_info_idx > exact color > similar color > type-only

Closes #245

backend/tests/unit/test_scheduler_ams_mapping.py

@@ -265,3 +265,166 @@ class TestMatchFilamentsToSlots:
 
         result = scheduler._match_filaments_to_slots(required, loaded)
         assert result == [254]
+
+    def test_match_by_tray_info_idx_priority(self, scheduler):
+        """tray_info_idx match should have highest priority over color match."""
+        required = [{"slot_id": 1, "type": "PLA", "color": "#000000", "tray_info_idx": "GFA00"}]
+        loaded = [
+            {
+                "type": "PLA",
+                "color": "#000000",
+                "global_tray_id": 0,
+                "tray_info_idx": "GFB00",
+            },  # Same color, different spool
+            {
+                "type": "PLA",
+                "color": "#000000",
+                "global_tray_id": 1,
+                "tray_info_idx": "GFA00",
+            },  # Same color, exact spool
+            {
+                "type": "PLA",
+                "color": "#000000",
+                "global_tray_id": 2,
+                "tray_info_idx": "GFC00",
+            },  # Same color, different spool
+        ]
+
+        result = scheduler._match_filaments_to_slots(required, loaded)
+        assert result == [1]  # Should pick tray 1 (exact tray_info_idx match)
+
+    def test_match_by_tray_info_idx_with_different_colors(self, scheduler):
+        """tray_info_idx match should work even if colors differ slightly."""
+        required = [{"slot_id": 1, "type": "PLA", "color": "#000000", "tray_info_idx": "P4d64437"}]
+        loaded = [
+            {"type": "PLA", "color": "#000000", "global_tray_id": 0, "tray_info_idx": ""},  # No idx
+            {
+                "type": "PLA",
+                "color": "#000010",
+                "global_tray_id": 3,
+                "tray_info_idx": "P4d64437",
+            },  # Exact spool (slightly different color reported)
+        ]
+
+        result = scheduler._match_filaments_to_slots(required, loaded)
+        assert result == [3]  # Should pick tray 3 (exact tray_info_idx match)
+
+    def test_match_fallback_to_color_when_no_tray_info_idx(self, scheduler):
+        """Should fall back to color matching when tray_info_idx is empty."""
+        required = [{"slot_id": 1, "type": "PLA", "color": "#FF0000", "tray_info_idx": ""}]
+        loaded = [
+            {"type": "PLA", "color": "#00FF00", "global_tray_id": 0, "tray_info_idx": "GFA00"},
+            {"type": "PLA", "color": "#FF0000", "global_tray_id": 1, "tray_info_idx": "GFB00"},  # Color match
+        ]
+
+        result = scheduler._match_filaments_to_slots(required, loaded)
+        assert result == [1]  # Should pick tray 1 (color match)
+
+    def test_match_fallback_to_color_when_no_matching_tray_info_idx(self, scheduler):
+        """Should fall back to color when tray_info_idx doesn't match any loaded spool."""
+        required = [{"slot_id": 1, "type": "PLA", "color": "#FF0000", "tray_info_idx": "OLD_SPOOL"}]
+        loaded = [
+            {
+                "type": "PLA",
+                "color": "#FF0000",
+                "global_tray_id": 0,
+                "tray_info_idx": "NEW_SPOOL",
+            },  # Different idx but same color
+        ]
+
+        result = scheduler._match_filaments_to_slots(required, loaded)
+        assert result == [0]  # Should fall back to color match
+
+    def test_match_multiple_same_color_with_tray_info_idx(self, scheduler):
+        """Multiple identical filaments should be matched by tray_info_idx (H2D Pro scenario)."""
+        # This is the exact scenario from issue #245 - 3 black PLA spools
+        required = [
+            {"slot_id": 1, "type": "PLA", "color": "#000000", "tray_info_idx": "GFA03"},  # Wants tray 3
+        ]
+        loaded = [
+            {"type": "PLA", "color": "#000000", "global_tray_id": 0, "tray_info_idx": "GFA00"},  # Tray 0
+            {"type": "PLA", "color": "#000000", "global_tray_id": 1, "tray_info_idx": "GFA01"},  # Tray 1
+            {"type": "PLA", "color": "#000000", "global_tray_id": 2, "tray_info_idx": "GFA02"},  # Tray 2
+            {
+                "type": "PLA",
+                "color": "#000000",
+                "global_tray_id": 3,
+                "tray_info_idx": "GFA03",
+            },  # Tray 3 - the one we want
+        ]
+
+        result = scheduler._match_filaments_to_slots(required, loaded)
+        assert result == [3]  # Should pick tray 3, not tray 0
+
+    def test_match_tray_info_idx_not_reused(self, scheduler):
+        """tray_info_idx matched trays should not be reused for other slots."""
+        required = [
+            {"slot_id": 1, "type": "PLA", "color": "#000000", "tray_info_idx": "GFA00"},
+            {"slot_id": 2, "type": "PLA", "color": "#000000", "tray_info_idx": "GFA01"},
+        ]
+        loaded = [
+            {"type": "PLA", "color": "#000000", "global_tray_id": 0, "tray_info_idx": "GFA00"},
+            {"type": "PLA", "color": "#000000", "global_tray_id": 1, "tray_info_idx": "GFA01"},
+        ]
+
+        result = scheduler._match_filaments_to_slots(required, loaded)
+        assert result == [0, 1]  # Each slot gets its specific tray
+
+
+class TestBuildLoadedFilamentsTrayInfoIdx:
+    """Test tray_info_idx extraction in _build_loaded_filaments."""
+
+    @pytest.fixture
+    def scheduler(self):
+        return PrintScheduler()
+
+    def test_build_loaded_filaments_includes_tray_info_idx(self, scheduler):
+        """Should extract tray_info_idx from AMS trays."""
+
+        class MockStatus:
+            raw_data = {
+                "ams": [
+                    {
+                        "id": 0,
+                        "tray": [
+                            {"id": 0, "tray_type": "PLA", "tray_color": "000000", "tray_info_idx": "GFA00"},
+                            {"id": 1, "tray_type": "PLA", "tray_color": "000000", "tray_info_idx": "GFA01"},
+                        ],
+                    }
+                ]
+            }
+
+        result = scheduler._build_loaded_filaments(MockStatus())
+        assert len(result) == 2
+        assert result[0]["tray_info_idx"] == "GFA00"
+        assert result[1]["tray_info_idx"] == "GFA01"
+
+    def test_build_loaded_filaments_empty_tray_info_idx(self, scheduler):
+        """Missing tray_info_idx should default to empty string."""
+
+        class MockStatus:
+            raw_data = {
+                "ams": [
+                    {
+                        "id": 0,
+                        "tray": [
+                            {"id": 0, "tray_type": "PLA", "tray_color": "FF0000"},  # No tray_info_idx
+                        ],
+                    }
+                ]
+            }
+
+        result = scheduler._build_loaded_filaments(MockStatus())
+        assert len(result) == 1
+        assert result[0]["tray_info_idx"] == ""
+
+    def test_build_loaded_filaments_external_spool_tray_info_idx(self, scheduler):
+        """Should extract tray_info_idx from external spool."""
+
+        class MockStatus:
+            raw_data = {"vt_tray": {"tray_type": "TPU", "tray_color": "0000FF", "tray_info_idx": "P4d64437"}}
+
+        result = scheduler._build_loaded_filaments(MockStatus())
+        assert len(result) == 1
+        assert result[0]["tray_info_idx"] == "P4d64437"
+        assert result[0]["is_external"] is True