test(networking): add end-to-end req/resp protocol message vectors

tests/consensus/devnet/networking/test_reqresp_codec.py

@@ -124,3 +124,73 @@ def test_response_success_all_ff(networking_codec: NetworkingCodecTestFiller) ->
         codec_name="reqresp_response",
         input={"responseCode": 0, "sszData": "0x" + "ff" * 32},
     )
+
+
+# --- End-to-end protocol messages ---
+#
+# Full stack: SSZ container → wire encode → wire decode → SSZ decode.
+# These use the actual Lean consensus message types, not arbitrary bytes.
+
+STATUS_SSZ = (
+    "0x01010101010101010101010101010101010101010101010101010101010101016400"
+    "000000000000020202020202020202020202020202020202020202020202020202020202"
+    "02020296000000000000"
+)
+"""Status(finalized=Checkpoint(0x01..01, slot=100), head=Checkpoint(0x02..02, slot=150))."""
+
+BLOCKS_BY_ROOT_SSZ = (
+    "0x04000000aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+    "aaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
+)
+"""BlocksByRootRequest with two roots (0xaa..aa, 0xbb..bb)."""
+
+BLOCKS_BY_ROOT_EMPTY_SSZ = "0x04000000"
+"""BlocksByRootRequest with empty root list (4-byte SSZ offset only)."""
+
+
+def test_request_status(networking_codec: NetworkingCodecTestFiller) -> None:
+    """Status request through the full wire pipeline. Protocol: /leanconsensus/req/status/1."""
+    networking_codec(
+        codec_name="reqresp_request",
+        input={"sszData": STATUS_SSZ},
+    )
+
+
+def test_response_status(networking_codec: NetworkingCodecTestFiller) -> None:
+    """Status SUCCESS response through the full wire pipeline."""
+    networking_codec(
+        codec_name="reqresp_response",
+        input={"responseCode": 0, "sszData": STATUS_SSZ},
+    )
+
+
+def test_request_blocks_by_root(networking_codec: NetworkingCodecTestFiller) -> None:
+    """BlocksByRoot request with two roots. Protocol: /leanconsensus/req/blocks_by_root/1."""
+    networking_codec(
+        codec_name="reqresp_request",
+        input={"sszData": BLOCKS_BY_ROOT_SSZ},
+    )
+
+
+def test_request_blocks_by_root_empty(networking_codec: NetworkingCodecTestFiller) -> None:
+    """BlocksByRoot request with empty root list. Minimal 4-byte SSZ payload."""
+    networking_codec(
+        codec_name="reqresp_request",
+        input={"sszData": BLOCKS_BY_ROOT_EMPTY_SSZ},
+    )
+
+
+def test_request_snappy_chunk_boundary(networking_codec: NetworkingCodecTestFiller) -> None:
+    """Request at Snappy chunk boundary (65536 bytes). Exercises multi-chunk framing."""
+    networking_codec(
+        codec_name="reqresp_request",
+        input={"sszData": "0x" + "ab" * 65536},
+    )
+
+
+def test_request_multi_chunk(networking_codec: NetworkingCodecTestFiller) -> None:
+    """Request spanning 2+ Snappy chunks (65537 bytes)."""
+    networking_codec(
+        codec_name="reqresp_request",
+        input={"sszData": "0x" + "cd" * 65537},
+    )