feat: add paintKit field to Sticker for sticker slab identification

Proto field 12 inside the Sticker sub-message encodes the actual sticker
slab variant ID. Previously this field was silently ignored, causing all
Sticker Slabs to decode identically (stickerId=37 for all variants).

paintKit maps to the sticker catalog ID (stickers.json) and uniquely
identifies which Sticker Slab variant an item is.

Add decode/encode support and two test vectors:
- NaVi (Holo) | Copenhagen 2024: defIndex=1355, rarity=5, paintKit=7256
- Eco Rush: defIndex=1355, rarity=3, paintKit=275

Author: vlydev

cs2_inspect/models.py

@@ -25,6 +25,7 @@ class Sticker:
     offset_z: Optional[float] = None
     pattern: int = 0
     highlight_reel: Optional[int] = None
+    paint_kit: Optional[int] = None
 
 
 @dataclass

cs2_inspect/proto.py

@@ -213,6 +213,8 @@ def encode_sticker(s: "Sticker") -> bytes:  # noqa: F821  (forward ref ok)
     w.write_uint32(10, s.pattern)
     if s.highlight_reel is not None:
         w.write_uint32(11, s.highlight_reel)
+    if s.paint_kit is not None:
+        w.write_uint32(12, s.paint_kit)
     return w.to_bytes()
 
 
@@ -243,6 +245,8 @@ def decode_sticker(data: bytes) -> "Sticker":  # noqa: F821
             s.pattern = value
         elif field_num == 11:
             s.highlight_reel = value
+        elif field_num == 12:
+            s.paint_kit = value
     return s
 
 

tests/test_inspect_link.py

@@ -408,3 +408,72 @@ def test_null_paintwear_roundtrip(self):
         data = ItemPreviewData(defindex=7, paintwear=None)
         result = deserialize(serialize(data))
         assert result.paintwear is None
+
+
+# ---------------------------------------------------------------------------
+# Sticker Slab test vectors (defIndex=1355, quality=8, slab variant via paint_kit)
+# ---------------------------------------------------------------------------
+
+# URL A — rarity=5, keychains[0].sticker_id=37, keychains[0].paint_kit=7256
+SLAB_URL_A = (
+    'steam://run/730//+csgo_econ_action_preview%20'
+    '918191895A9BB191B994A199F991E191339096999181B4F149A98D5C0889'
+)
+
+# URL B — rarity=3, keychains[0].sticker_id=37, keychains[0].paint_kit=275
+SLAB_URL_B = (
+    'steam://run/730//+csgo_econ_action_preview%20'
+    'CBDBCBD300C1EBCBE3C8FBC3A3CBBBCB69CACCC3CBDBEEAB58C9B8B67C83'
+)
+
+
+class TestStickerSlabVectors:
+    def test_slab_a_defindex(self):
+        assert deserialize(SLAB_URL_A).defindex == 1355
+
+    def test_slab_a_quality(self):
+        assert deserialize(SLAB_URL_A).quality == 8
+
+    def test_slab_a_rarity(self):
+        assert deserialize(SLAB_URL_A).rarity == 5
+
+    def test_slab_a_keychain_sticker_id(self):
+        keychains = deserialize(SLAB_URL_A).keychains
+        assert len(keychains) == 1
+        assert keychains[0].sticker_id == 37
+
+    def test_slab_a_keychain_paint_kit(self):
+        keychains = deserialize(SLAB_URL_A).keychains
+        assert len(keychains) == 1
+        assert keychains[0].paint_kit == 7256
+
+    def test_slab_b_defindex(self):
+        assert deserialize(SLAB_URL_B).defindex == 1355
+
+    def test_slab_b_quality(self):
+        assert deserialize(SLAB_URL_B).quality == 8
+
+    def test_slab_b_rarity(self):
+        assert deserialize(SLAB_URL_B).rarity == 3
+
+    def test_slab_b_keychain_sticker_id(self):
+        keychains = deserialize(SLAB_URL_B).keychains
+        assert len(keychains) == 1
+        assert keychains[0].sticker_id == 37
+
+    def test_slab_b_keychain_paint_kit(self):
+        keychains = deserialize(SLAB_URL_B).keychains
+        assert len(keychains) == 1
+        assert keychains[0].paint_kit == 275
+
+    def test_paint_kit_roundtrip(self):
+        data = ItemPreviewData(
+            defindex=1355,
+            quality=8,
+            rarity=5,
+            keychains=[Sticker(slot=0, sticker_id=37, paint_kit=7256)],
+        )
+        result = deserialize(serialize(data))
+        assert len(result.keychains) == 1
+        assert result.keychains[0].sticker_id == 37
+        assert result.keychains[0].paint_kit == 7256