fix: do not construct IntEnum for unknown dtype/selector_mode

_RoutingDtype(int) and _SelectorMode(int) raise ValueError for any
value not in the enum, so the .get() fallback was unreachable: a
future routing_dtype=3 in the header would crash metadata
construction before str(int) could run.

Look up names by raw int instead — IntEnum keys hash-equal their int
values, so known modes resolve to their lowercase name and unknown
ones fall back to str(int) without ever constructing the enum.
Adds a regression test exercising routing_dtype=99.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: SunnySoldier357

eval_protocol/adapters/r3_deserializer.py

@@ -179,12 +179,8 @@ def decompress_and_parse_r3(
         matrices[pos] = base64.b64encode(matrix_bytes[start:end]).decode("ascii")
 
     metadata: Dict[str, Any] = {
-        "routing_dtype": _ROUTING_DTYPE_NAMES.get(
-            _RoutingDtype(routing_dtype), str(routing_dtype)
-        ),
-        "selector_mode": _SELECTOR_MODE_NAMES.get(
-            _SelectorMode(selector_mode), str(selector_mode)
-        ),
+        "routing_dtype": _ROUTING_DTYPE_NAMES.get(routing_dtype, str(routing_dtype)),
+        "selector_mode": _SELECTOR_MODE_NAMES.get(selector_mode, str(selector_mode)),
         "total_token_count": total_token_count,
         "replayed_token_count": replayed_token_count,
         "replay_start_token": replay_start_token,

tests/adapters/test_r3_deserializer.py

@@ -266,6 +266,20 @@ def test_zero_replayed_tokens(self):
         assert all(m is None for m in matrices)
         assert metadata["replayed_token_count"] == 0
 
+    def test_unknown_routing_dtype_falls_back_to_str(self):
+        """Unknown routing_dtype ints (e.g. a future dtype=3) must not crash
+        metadata construction; the dtype is surfaced as its string repr."""
+        raw = _make_raw_r3(
+            routing_dtype=99,  # not in _RoutingDtype
+            total_token_count=2,
+            replayed_token_count=2,
+            matrix_data=b"\x00" * 8,
+        )
+        blob = _compress_and_b64(raw)
+
+        _, metadata = decompress_and_parse_r3(blob)
+        assert metadata["routing_dtype"] == "99"
+
     def test_high_compression_ratio_payload(self):
         """Highly compressible payloads (e.g. tokens routing to the same
         experts) can compress much better than 20:1; the deserializer must