refactor(python): simplify THP pairing state handling

diff --git a/python/src/trezorlib/client.py b/python/src/trezorlib/client.py
index 85158da9..d45d1679 100644
--- a/python/src/trezorlib/client.py
+++ b/python/src/trezorlib/client.py
@@ -29,7 +29,7 @@ from .transport import Transport, get_transport
 from .transport.thp.channel import Channel
 from .transport.thp.cpace import Cpace
 from .transport.thp.protocol_v1 import ProtocolV1Channel, UnexpectedMagicError
-from .transport.thp.protocol_v2 import ProtocolV2Channel, TrezorState
+from .transport.thp.protocol_v2 import ProtocolV2Channel
 
 if t.TYPE_CHECKING:
     from .transport.session import Session, SessionV1, SessionV2
@@ -120,6 +120,7 @@ class TrezorClient:
                 raise RuntimeError(
                     "Connected Trezor does not support any trezorlib-compatible pairing method."
                 )
+        LOG.debug("Starting pairing: %r", pairing_method)
         session = SessionV2.seedless(self)
         session.call(
             messages.ThpPairingRequest(host_name="Trezorlib"),
@@ -142,7 +143,7 @@ class TrezorClient:
             skip_firmware_version_check=True,
         )
         assert isinstance(self.protocol, ProtocolV2Channel)
-        self.protocol._has_valid_channel = True
+        self.protocol._is_paired = True
 
     def _handle_code_entry(self, session: SessionV2) -> None:
         from .cli import get_code_entry_code
@@ -209,7 +210,7 @@ class TrezorClient:
         )
 
         assert isinstance(self.protocol, ProtocolV2Channel)
-        self.protocol._has_valid_channel = True
+        self.protocol._is_paired = True
 
     def get_session(
         self,
@@ -240,7 +241,7 @@ class TrezorClient:
         if isinstance(self.protocol, ProtocolV2Channel):
             from .transport.session import SessionV2
 
-            if self.protocol.trezor_state is TrezorState.UNPAIRED:
+            if not self.protocol._is_paired:
                 self.do_pairing()
 
             if passphrase is SEEDLESS:
@@ -273,10 +274,7 @@ class TrezorClient:
 
     def _get_features(self) -> messages.Features:
         if isinstance(self.protocol, ProtocolV2Channel):
-            if (
-                self.protocol.trezor_state is TrezorState.UNPAIRED
-                or not self.protocol._has_valid_channel
-            ):
+            if not self.protocol._is_paired:
                 self.do_pairing()
         return self.protocol.get_features()
 
diff --git a/python/src/trezorlib/transport/thp/protocol_v2.py b/python/src/trezorlib/transport/thp/protocol_v2.py
index 7a56a578..2d85b6c6 100644
--- a/python/src/trezorlib/transport/thp/protocol_v2.py
+++ b/python/src/trezorlib/transport/thp/protocol_v2.py
@@ -20,7 +20,6 @@ import logging
 import os
 import typing as t
 from binascii import hexlify
-from enum import IntEnum
 
 from noise.connection import Keypair, NoiseConnection
 
@@ -44,11 +43,6 @@ if t.TYPE_CHECKING:
 MT = t.TypeVar("MT", bound=protobuf.MessageType)
 
 
-class TrezorState(IntEnum):
-    UNPAIRED = 0x00
-    PAIRED = 0x01
-
-
 class ProtocolV2Channel(Channel):
     channel_id: int
     sync_bit_send: int
@@ -56,9 +50,8 @@ class ProtocolV2Channel(Channel):
     handshake_hash: bytes
     device_properties: bytes
 
-    _has_valid_channel: bool = False
     _features: messages.Features | None = None
-    trezor_state: int = TrezorState.UNPAIRED
+    _is_paired: bool = False
 
     def __init__(
         self,
@@ -72,11 +65,13 @@ class ProtocolV2Channel(Channel):
         if prepare_channel_without_pairing:
             # allow skipping unrelated response packets (e.g. in case of retransmissions)
             self._do_channel_allocation(retries=MAX_RETRANSMISSION_COUNT)
-            self.trezor_state = self._do_handshake(credential=credential)
+            LOG.debug("THP channel allocated: %04x", self.channel_id)
+            self._do_handshake(credential=credential)
+            LOG.debug("THP handshake done: is_paired=%s", self._is_paired)
 
     def get_channel(self) -> ProtocolV2Channel:
-        if not self._has_valid_channel:
-            raise RuntimeError("Channel is invalidated")
+        if not self._is_paired:
+            raise RuntimeError("Channel is not paired")
         return self
 
     def read(self, session_id: int, timeout: float | None = None) -> t.Any:
@@ -92,8 +87,8 @@ class ProtocolV2Channel(Channel):
         self._encrypt_and_write(session_id, msg_type, msg_data)
 
     def get_features(self) -> messages.Features:
-        if not self._has_valid_channel:
-            raise RuntimeError("Channel is invalidated")
+        if not self._is_paired:
+            raise RuntimeError("Channel is not paired")
         if self._features is None:
             self.update_features()
         assert self._features is not None
@@ -205,7 +200,7 @@ class ProtocolV2Channel(Channel):
         credential: bytes | None = None,
         host_static_randomness: bytes | None = None,
         host_ephemeral_randomness: bytes | None = None,
-    ) -> int:
+    ) -> None:
 
         randomness_static = host_static_randomness or os.urandom(32)
         if host_ephemeral_randomness is not None:
@@ -268,15 +263,15 @@ class ProtocolV2Channel(Channel):
         )
         self.handshake_hash = self._noise.get_handshake_hash()
 
-    def _read_handshake_completion_response(self) -> int:
-        # Read handshake completion response, ignore payload as we do not care about the state
+    def _read_handshake_completion_response(self) -> None:
+        # Read handshake completion response
         header, data = self._read_until_valid_crc_check()
         if not header.is_handshake_comp_response():
             LOG.error("Received message is not a valid handshake completion response")
         trezor_state = self._noise.decrypt(bytes(data))
         assert trezor_state == b"\x00" or trezor_state == b"\x01"
         self._send_ack_bit(bit=1)
-        return int.from_bytes(trezor_state, "big")
+        self._is_paired = bool(int.from_bytes(trezor_state, "big"))
 
     def _read_ack(self):
         header, payload = self._read_until_valid_crc_check()
diff --git a/tests/device_tests/thp/test_pairing.py b/tests/device_tests/thp/test_pairing.py
index 63186abc..12b35eec 100644
--- a/tests/device_tests/thp/test_pairing.py
+++ b/tests/device_tests/thp/test_pairing.py
@@ -101,7 +101,7 @@ def test_pairing_qr_code(client: Client) -> None:
     protocol._send_message(ThpEndRequest())
     protocol._read_message(ThpEndResponse)
 
-    protocol._has_valid_channel = True
+    protocol._is_paired = True
 
 
 @pytest.mark.filterwarnings(
@@ -172,7 +172,7 @@ def test_pairing_code_entry(
     protocol._send_message(ThpEndRequest())
     protocol._read_message(ThpEndResponse)
 
-    protocol._has_valid_channel = True
+    protocol._is_paired = True
 
 
 @pytest.mark.filterwarnings(
@@ -241,7 +241,7 @@ def test_pairing_nfc(client: Client) -> None:
 
     protocol._send_message(ThpEndRequest())
     protocol._read_message(ThpEndResponse)
-    protocol._has_valid_channel = True
+    protocol._is_paired = True
 
 
 def _nfc_pairing(client: Client, protocol: ProtocolV2Channel) -> None:
@@ -486,9 +486,9 @@ def test_credential_request_in_encrypted_transport_phase(client: Client) -> None
     credential = credential_response.credential
     protocol._send_message(ThpEndRequest())
     protocol._read_message(ThpEndResponse)
+    protocol._is_paired = True  # pairing has been done above
 
     session = client.get_seedless_session()
-
     session.call(
         ThpCredentialRequest(
             host_static_public_key=host_static_public_key,