feat: implement DGR-006 tensor bundle boundary

packages/node/meshnet_node/native_protocol/codec.py

@@ -328,6 +328,8 @@ def decode_tensor(
 def encode_bundle(
     tensors: Iterable[pb.NamedTensor],
     *,
+    architecture: int = pb.ARCHITECTURE_TYPE_UNSPECIFIED,
+    boundary_point: str = "",
     max_chunk_bytes: int = DEFAULT_MAX_CHUNK_BYTES,
     max_tensors: int = DEFAULT_MAX_TENSORS_PER_BUNDLE,
 ) -> pb.TensorBundle:
@@ -338,7 +340,12 @@ def encode_bundle(
         raise ProtocolError(
             f"bundle carries {len(tensor_list)} tensors, exceeding limit {max_tensors}"
         )
-    bundle = pb.TensorBundle(bundle_version=BUNDLE_VERSION, tensors=tensor_list)
+    bundle = pb.TensorBundle(
+        bundle_version=BUNDLE_VERSION,
+        tensors=tensor_list,
+        architecture=architecture,
+        boundary_point=boundary_point,
+    )
     if bundle.ByteSize() > max_chunk_bytes:
         raise ProtocolError(
             f"serialized tensor bundle exceeds the {max_chunk_bytes}-byte "
@@ -392,6 +399,80 @@ def decode_bundle(
     return payloads
 
 
+def encode_decode_step(
+    bundle: pb.TensorBundle,
+    *,
+    idempotency_step: int,
+    position: int,
+    expected_past_len: int,
+    work_id: str,
+    deadline_unix_nanos: int = 0,
+    prefer_compact_one_tensor: bool = True,
+) -> pb.DecodeStep:
+    """Encode a decode boundary, retaining the deliberate compact fallback."""
+    step = pb.DecodeStep(
+        idempotency_step=idempotency_step,
+        position=position,
+        expected_past_len=expected_past_len,
+        work_id=work_id,
+        deadline_unix_nanos=deadline_unix_nanos,
+    )
+    if prefer_compact_one_tensor and len(bundle.tensors) == 1:
+        step.tensor.CopyFrom(bundle.tensors[0])
+    else:
+        step.bundle.CopyFrom(bundle)
+    return step
+
+
+def validate_tail_result(result: pb.TailResult) -> None:
+    """Fail closed unless a tail completion is bound to its exact recipe."""
+    identity = result.identity
+    required = (
+        identity.request_id,
+        identity.runtime_recipe_digest,
+        identity.chat_template_id,
+        identity.chat_template_version,
+        identity.reasoning_mode,
+    )
+    if not all(required) or identity.architecture == pb.ARCHITECTURE_TYPE_UNSPECIFIED:
+        raise ProtocolError("tail result lacks exact request/recipe/template identity")
+    if result.WhichOneof("output") not in {"logits", "sampled_token_id"}:
+        raise ProtocolError("tail result lacks logits or sampled token output")
+
+
+def decode_step_bundle(
+    step: pb.DecodeStep,
+    *,
+    max_chunk_bytes: int = DEFAULT_MAX_CHUNK_BYTES,
+    max_fragment_bytes: int = DEFAULT_MAX_FRAGMENT_BYTES,
+    max_fragments: int = DEFAULT_MAX_FRAGMENTS_PER_TENSOR,
+    max_tensors: int = DEFAULT_MAX_TENSORS_PER_BUNDLE,
+) -> dict[str, bytes]:
+    """Decode a fast-path boundary with the DGR-006 compatibility rule.
+
+    `bundle` is authoritative because it can carry architecture sidebands. The
+    old `tensor` field remains the compact representation for a certified
+    one-tensor boundary and is accepted by new readers during rollout.
+    """
+    if step.HasField("bundle"):
+        return decode_bundle(
+            step.bundle,
+            max_chunk_bytes=max_chunk_bytes,
+            max_fragment_bytes=max_fragment_bytes,
+            max_fragments=max_fragments,
+            max_tensors=max_tensors,
+        )
+    if step.HasField("tensor"):
+        return decode_bundle(
+            encode_bundle([step.tensor], max_chunk_bytes=max_chunk_bytes),
+            max_chunk_bytes=max_chunk_bytes,
+            max_fragment_bytes=max_fragment_bytes,
+            max_fragments=max_fragments,
+            max_tensors=max_tensors,
+        )
+    raise ProtocolError("decode step carries neither TensorBundle nor legacy tensor")
+
+
 def validate_session_message_size(
     message: pb.SessionRequest | pb.SessionResponse,
     *,