feat(cfold): canonicalize custom test layout

tests/mumble/custom/test_protocol_handshake.py

@@ -0,0 +1,31 @@
+"""mumble — protocol integration parity port (Phase 2 P2 + §4.3 recipe-specific depth).
+
+SOURCE: recipe-info/mumble/tests/mumble_connect.py — "connects via TLS, authenticates, verifies
+server version, channel list, welcome text, and ServerSync handshake. Zero external dependencies."
+
+This is mumble's characteristic "is it really working" check: the voice server has no HTTP API, so
+the meaningful liveness/behaviour proof is the control-channel handshake — a TLS connection that is
+ACCEPTED (anonymous auth, no Reject), receives the server Version, sees the root channel
+(channel presence — §4.3 "channel presence beyond TCP health"), and completes with ServerSync.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(__file__))
+import _mumble_proto  # noqa: E402
+
+
+def test_handshake_completes_with_channel_presence(live_app):
+    r = _mumble_proto.retry_handshake(attempts=12, interval=5.0)
+
+    assert r["tls_connect"], f"TLS connection to 127.0.0.1:64738 failed — {r.get('error')}"
+    assert r["server_version"] is not None, "server did not send a Version message"
+    assert r["auth_accepted"], f"authentication not accepted — {r.get('error')}"
+    # Channel presence: the server must expose at least the root channel (beyond a bare TCP open).
+    assert (
+        len(r["channels"]) >= 1
+    ), f"server reported no channels (expected >=1 root channel) — {r!r}"
+    assert r["server_sync"], f"ServerSync handshake did not complete — {r.get('error')}"