fix(core): make app_name required for THP pairing

diff --git a/common/protob/messages-thp.proto b/common/protob/messages-thp.proto
index 4581e2a6e..3e366f60c 100644
--- a/common/protob/messages-thp.proto
+++ b/common/protob/messages-thp.proto
@@ -98,8 +98,8 @@ message ThpCreateNewSession {
  * @next ThpPairingRequestApproved
  */
 message ThpPairingRequest {
-    optional string host_name = 1;     // Human-readable host name (browser name for web apps)
-    optional string app_name = 2;      // Human-readable application name
+    required string host_name = 1;     // Human-readable host name (browser name for web apps)
+    required string app_name = 2;      // Human-readable application name
 }
 
 /**
diff --git a/core/src/apps/thp/pairing.py b/core/src/apps/thp/pairing.py
index 266e62e97..44213c445 100644
--- a/core/src/apps/thp/pairing.py
+++ b/core/src/apps/thp/pairing.py
@@ -111,9 +111,10 @@ async def handle_pairing_request(
     if not ThpPairingRequest.is_type_of(message):
         raise UnexpectedMessage("Unexpected message")
 
-    # TODO: make app_name required eventually
     if not message.host_name:
         raise DataError("Missing host_name.")
+    if not message.app_name:
+        raise DataError("Missing app_name.")
 
     peer_addr = ctx.channel_ctx.iface_ctx.connected_addr()
     await ui.show_pairing_dialog(message.host_name, message.app_name)
diff --git a/core/src/trezor/messages.py b/core/src/trezor/messages.py
index 907e4f3dd..cbabaa3b3 100644
--- a/core/src/trezor/messages.py
+++ b/core/src/trezor/messages.py
@@ -6377,14 +6377,14 @@ if TYPE_CHECKING:
             return isinstance(msg, cls)
 
     class ThpPairingRequest(protobuf.MessageType):
-        host_name: "str | None"
-        app_name: "str | None"
+        host_name: "str"
+        app_name: "str"
 
         def __init__(
             self,
             *,
-            host_name: "str | None" = None,
-            app_name: "str | None" = None,
+            host_name: "str",
+            app_name: "str",
         ) -> None:
             pass
 
diff --git a/python/src/trezorlib/messages.py b/python/src/trezorlib/messages.py
index 3a519e90a..da336e75a 100644
--- a/python/src/trezorlib/messages.py
+++ b/python/src/trezorlib/messages.py
@@ -8141,15 +8141,15 @@ class ThpCreateNewSession(protobuf.MessageType):
 class ThpPairingRequest(protobuf.MessageType):
     MESSAGE_WIRE_TYPE = 1008
     FIELDS = {
-        1: protobuf.Field("host_name", "string", repeated=False, required=False, default=None),
-        2: protobuf.Field("app_name", "string", repeated=False, required=False, default=None),
+        1: protobuf.Field("host_name", "string", repeated=False, required=True),
+        2: protobuf.Field("app_name", "string", repeated=False, required=True),
     }
 
     def __init__(
         self,
         *,
-        host_name: Optional["str"] = None,
-        app_name: Optional["str"] = None,
+        host_name: "str",
+        app_name: "str",
     ) -> None:
         self.host_name = host_name
         self.app_name = app_name
diff --git a/rust/trezor-client/src/protos/generated/messages_thp.rs b/rust/trezor-client/src/protos/generated/messages_thp.rs
index d9788a32a..144d4aca9 100644
--- a/rust/trezor-client/src/protos/generated/messages_thp.rs
+++ b/rust/trezor-client/src/protos/generated/messages_thp.rs
@@ -737,7 +737,7 @@ impl ThpPairingRequest {
         ::std::default::Default::default()
     }
 
-    // optional string host_name = 1;
+    // required string host_name = 1;
 
     pub fn host_name(&self) -> &str {
         match self.host_name.as_ref() {
@@ -773,7 +773,7 @@ impl ThpPairingRequest {
         self.host_name.take().unwrap_or_else(|| ::std::string::String::new())
     }
 
-    // optional string app_name = 2;
+    // required string app_name = 2;
 
     pub fn app_name(&self) -> &str {
         match self.app_name.as_ref() {
@@ -834,6 +834,12 @@ impl ::protobuf::Message for ThpPairingRequest {
     const NAME: &'static str = "ThpPairingRequest";
 
     fn is_initialized(&self) -> bool {
+        if self.host_name.is_none() {
+            return false;
+        }
+        if self.app_name.is_none() {
+            return false;
+        }
         true
     }
 
@@ -4699,8 +4705,8 @@ static file_descriptor_proto_data: &'static [u8] = b"\
     ateNewSession\x12\x1e\n\npassphrase\x18\x01\x20\x01(\tR\npassphrase\x12\
     \"\n\ton_device\x18\x02\x20\x01(\x08:\x05falseR\x08onDevice\x12,\n\x0ede\
     rive_cardano\x18\x03\x20\x01(\x08:\x05falseR\rderiveCardano\"K\n\x11ThpP\
-    airingRequest\x12\x1b\n\thost_name\x18\x01\x20\x01(\tR\x08hostName\x12\
-    \x19\n\x08app_name\x18\x02\x20\x01(\tR\x07appName\"\x1b\n\x19ThpPairingR\
+    airingRequest\x12\x1b\n\thost_name\x18\x01\x20\x02(\tR\x08hostName\x12\
+    \x19\n\x08app_name\x18\x02\x20\x02(\tR\x07appName\"\x1b\n\x19ThpPairingR\
     equestApproved\"s\n\x0fThpSelectMethod\x12`\n\x17selected_pairing_method\
     \x18\x01\x20\x02(\x0e2(.hw.trezor.messages.thp.ThpPairingMethodR\x15sele\
     ctedPairingMethod\"\x20\n\x1eThpPairingPreparationsFinished\"8\n\x16ThpC\
diff --git a/tests/device_tests/thp/connect.py b/tests/device_tests/thp/connect.py
index 85b45e847..9d0dff687 100644
--- a/tests/device_tests/thp/connect.py
+++ b/tests/device_tests/thp/connect.py
@@ -42,9 +42,9 @@ def get_encrypted_transport_protocol(
 
 
 def handle_pairing_request(
-    client: Client, protocol: ProtocolV2Channel, host_name: str | None = None
+    client: Client, protocol: ProtocolV2Channel, app_name: str | None = None
 ) -> None:
-    protocol._send_message(ThpPairingRequest(host_name=host_name))
+    protocol._send_message(ThpPairingRequest(host_name="localhost", app_name=app_name))
     button_req = protocol._read_message(ButtonRequest)
     assert button_req.name == "thp_pairing_request"
 
diff --git a/tests/device_tests/thp/test_pairing.py b/tests/device_tests/thp/test_pairing.py
index 12b35eec1..d83e46485 100644
--- a/tests/device_tests/thp/test_pairing.py
+++ b/tests/device_tests/thp/test_pairing.py
@@ -209,7 +209,9 @@ def test_pairing_code_entry_cancel(
 def test_pairing_cancel_1(client: Client) -> None:
     protocol = prepare_protocol_for_pairing(client)
 
-    protocol._send_message(ThpPairingRequest(host_name="TestTrezor Cancel 1"))
+    protocol._send_message(
+        ThpPairingRequest(host_name="localhost", app_name="TestTrezor Cancel 1")
+    )
     button_req = protocol._read_message(ButtonRequest)
     assert button_req.name == "thp_pairing_request"
 
@@ -224,7 +226,9 @@ def test_pairing_cancel_1(client: Client) -> None:
 def test_pairing_cancel_2(client: Client) -> None:
     protocol = prepare_protocol_for_pairing(client)
 
-    protocol._send_message(ThpPairingRequest(host_name="TestTrezor Cancel 2"))
+    protocol._send_message(
+        ThpPairingRequest(host_name="localhost", app_name="TestTrezor Cancel 2")
+    )
     button_req = protocol._read_message(ButtonRequest)
     assert button_req.name == "thp_pairing_request"