diff --git a/python/setprotocol/__init__.py b/python/setprotocol/__init__.py
new file mode 100644
index 0000000..8791acc
--- /dev/null
+++ b/python/setprotocol/__init__.py
@@ -0,0 +1,3 @@
+"""Cross-platform Python facade for the canonical SETProtocol core."""
+
+from .core import *  # noqa: F401,F403
diff --git a/python/setprotocol/core.py b/python/setprotocol/core.py
new file mode 100644
index 0000000..77caa6d
--- /dev/null
+++ b/python/setprotocol/core.py
@@ -0,0 +1,671 @@
+"""Эталонная Python-реализация SET protocol v2.
+
+Источник wire-контракта находится в ``templates/c/set-protocol/PROTOCOL.md``.
+Модуль не импортирует Qt и используется SETGUI, host-тестами и утилитами.
+"""
+
+from __future__ import annotations
+
+import binascii
+import hashlib
+import struct
+from dataclasses import dataclass
+from enum import IntEnum, IntFlag
+from typing import Iterable
+
+SOF = b"\xA5\x5A"
+VERSION = 0x02
+HEADER_SIZE = 14
+CRC_SIZE = 4
+MAX_PAYLOAD_SIZE = 512
+FRAME_MAX = HEADER_SIZE + MAX_PAYLOAD_SIZE + CRC_SIZE
+
+NODE_LOCAL = 0x0000
+NODE_BROADCAST = 0xFFFF
+
+
+class SetProtocolError(ValueError):
+    """Кадр или payload нарушает обязательный контракт SETP v2."""
+
+
+class FrameFlag(IntFlag):
+    RESPONSE = 0x01
+    EVENT = 0x02
+    ERROR = 0x04
+    ACK_REQUIRED = 0x08
+    MORE = 0x10
+    PRIORITY = 0x20
+
+
+KNOWN_FLAGS = int(
+    FrameFlag.RESPONSE
+    | FrameFlag.EVENT
+    | FrameFlag.ERROR
+    | FrameFlag.ACK_REQUIRED
+    | FrameFlag.MORE
+    | FrameFlag.PRIORITY
+)
+
+
+class MessageType(IntEnum):
+    PING = 0x0001
+    DEVICE_INFO = 0x0002
+    CAPABILITIES = 0x0003
+    DIAGNOSTICS = 0x0008
+    READ = 0x0009
+    WRITE = 0x000A
+    LOG_READ = 0x0010
+    CATALOG = 0x0011
+    SUBSCRIBE = 0x0012
+    PUBLISH = 0x0013
+    UNSUBSCRIBE = 0x0014
+
+    FW_BEGIN = 0x0100
+    FW_DATA = 0x0101
+    FW_END = 0x0102
+    FW_ABORT = 0x0103
+    FW_STATUS = 0x0104
+    FW_ACTIVATE = 0x0105
+
+
+class Status(IntEnum):
+    OK = 0
+    INVALID_ARGUMENT = 1
+    INVALID_LENGTH = 2
+    NOT_FOUND = 3
+    ACCESS_DENIED = 4
+    BUSY = 5
+    NO_PROVIDER = 6
+    INTERNAL = 7
+    CRC = 8
+    SEQUENCE = 9
+    NO_SPACE = 10
+    UNSUPPORTED = 11
+    VERIFY_FAILED = 12
+    AUTH_FAILED = 13
+    TIMEOUT = 14
+    WRONG_STATE = 15
+
+
+class Interface(IntEnum):
+    NONE = 0
+    RS232 = 1
+    RS485 = 2
+    CAN = 3
+    USB_CDC = 4
+    ETHERNET_TCP = 5
+    ETHERNET_UDP = 6
+
+
+class Feature(IntFlag):
+    READ = 1 << 0
+    WRITE = 1 << 1
+    CATALOG = 1 << 2
+    SUBSCRIBE = 1 << 3
+    LOG_READ = 1 << 4
+    FIRMWARE = 1 << 5
+    DIAGNOSTICS = 1 << 6
+
+
+class ValueEncoding(IntEnum):
+    U16 = 1
+    I16 = 2
+    U32 = 3
+    I32 = 4
+    F32 = 5
+    BYTES = 6
+
+
+class FirmwareFlag(IntFlag):
+    RESUME = 0x01
+    SIGNED = 0x02
+    ERASE_SLOT = 0x04
+    ACTIVATE = 0x08
+
+
+def crc32_ieee(data: bytes | bytearray | memoryview) -> int:
+    return binascii.crc32(data) & 0xFFFFFFFF
+
+
+def _u16(value: int, name: str) -> int:
+    if not 0 <= value <= 0xFFFF:
+        raise SetProtocolError(f"{name} вне диапазона u16")
+    return value
+
+
+def _u32(value: int, name: str) -> int:
+    if not 0 <= value <= 0xFFFFFFFF:
+        raise SetProtocolError(f"{name} вне диапазона u32")
+    return value
+
+
+@dataclass(frozen=True)
+class Frame:
+    message_type: int
+    sequence: int
+    payload: bytes = b""
+    flags: FrameFlag = FrameFlag(0)
+    source: int = NODE_LOCAL
+    destination: int = NODE_LOCAL
+
+    def __post_init__(self) -> None:
+        _u16(int(self.message_type), "message_type")
+        _u16(self.sequence, "sequence")
+        _u16(self.source, "source")
+        _u16(self.destination, "destination")
+        if int(self.flags) & ~KNOWN_FLAGS:
+            raise SetProtocolError("зарезервированные флаги должны быть нулевыми")
+        if len(self.payload) > MAX_PAYLOAD_SIZE:
+            raise SetProtocolError(f"payload превышает {MAX_PAYLOAD_SIZE} байт")
+
+
+def build_frame(frame: Frame) -> bytes:
+    protected = struct.pack(
+        "<BBHHHHH",
+        VERSION,
+        int(frame.flags),
+        int(frame.message_type),
+        frame.source,
+        frame.destination,
+        frame.sequence,
+        len(frame.payload),
+    ) + frame.payload
+    return SOF + protected + struct.pack("<I", crc32_ieee(protected))
+
+
+def decode_datagram(data: bytes | bytearray | memoryview) -> Frame:
+    """Разбирает ровно один SETP-кадр из UDP или другого datagram-носителя."""
+    packet = bytes(data)
+    if len(packet) < HEADER_SIZE + CRC_SIZE or packet[:2] != SOF:
+        raise SetProtocolError("датаграмма не содержит полный SETP-кадр")
+    if packet[2] != VERSION:
+        raise SetProtocolError(f"неподдерживаемая версия {packet[2]}")
+    if packet[3] & ~KNOWN_FLAGS:
+        raise SetProtocolError("зарезервированные флаги должны быть нулевыми")
+    payload_length = int.from_bytes(packet[12:14], "little")
+    if payload_length > MAX_PAYLOAD_SIZE:
+        raise SetProtocolError("payload датаграммы превышает лимит")
+    expected_length = HEADER_SIZE + payload_length + CRC_SIZE
+    if len(packet) != expected_length:
+        raise SetProtocolError("длина UDP-датаграммы не совпадает с SETP header")
+    if crc32_ieee(packet[2:-CRC_SIZE]) != int.from_bytes(packet[-CRC_SIZE:], "little"):
+        raise SetProtocolError("неверный CRC32 датаграммы")
+    _, flags, message_type, source, destination, sequence, _ = struct.unpack_from(
+        "<BBHHHHH", packet, 2
+    )
+    return Frame(
+        message_type=message_type,
+        sequence=sequence,
+        payload=packet[HEADER_SIZE:-CRC_SIZE],
+        flags=FrameFlag(flags),
+        source=source,
+        destination=destination,
+    )
+
+
+@dataclass
+class ParserStats:
+    frames: int = 0
+    crc_errors: int = 0
+    version_errors: int = 0
+    length_errors: int = 0
+    flag_errors: int = 0
+    stray_bytes: int = 0
+    overflows: int = 0
+
+
+class FrameParser:
+    """Потоковый parser для UART, USB CDC и Ethernet TCP."""
+
+    def __init__(self) -> None:
+        self._buffer = bytearray()
+        self.stats = ParserStats()
+
+    def reset(self) -> None:
+        self._buffer.clear()
+
+    @property
+    def buffered_bytes(self) -> int:
+        return len(self._buffer)
+
+    def feed(self, data: bytes | bytearray | memoryview) -> list[Frame]:
+        if not data:
+            return []
+        self._buffer.extend(data)
+
+        frames: list[Frame] = []
+        while True:
+            sof_index = self._buffer.find(SOF)
+            if sof_index < 0:
+                keep = 1 if self._buffer[-1:] == SOF[:1] else 0
+                self.stats.stray_bytes += len(self._buffer) - keep
+                self._buffer[:] = self._buffer[-1:] if keep else b""
+                break
+            if sof_index:
+                self.stats.stray_bytes += sof_index
+                del self._buffer[:sof_index]
+            if len(self._buffer) < HEADER_SIZE:
+                break
+            if self._buffer[2] != VERSION:
+                self.stats.version_errors += 1
+                del self._buffer[0]
+                continue
+            flags = self._buffer[3]
+            if flags & ~KNOWN_FLAGS:
+                self.stats.flag_errors += 1
+                del self._buffer[0]
+                continue
+            payload_length = int.from_bytes(self._buffer[12:14], "little")
+            if payload_length > MAX_PAYLOAD_SIZE:
+                self.stats.length_errors += 1
+                del self._buffer[0]
+                continue
+            total = HEADER_SIZE + payload_length + CRC_SIZE
+            if len(self._buffer) < total:
+                break
+            packet = bytes(self._buffer[:total])
+            protected = packet[2:-CRC_SIZE]
+            received_crc = int.from_bytes(packet[-CRC_SIZE:], "little")
+            if crc32_ieee(protected) != received_crc:
+                self.stats.crc_errors += 1
+                del self._buffer[0]
+                continue
+            (
+                _version,
+                _flags,
+                message_type,
+                source,
+                destination,
+                sequence,
+                _payload_length,
+            ) = struct.unpack_from("<BBHHHHH", packet, 2)
+            frames.append(
+                Frame(
+                    message_type=message_type,
+                    sequence=sequence,
+                    payload=packet[HEADER_SIZE : HEADER_SIZE + payload_length],
+                    flags=FrameFlag(flags),
+                    source=source,
+                    destination=destination,
+                )
+            )
+            self.stats.frames += 1
+            del self._buffer[:total]
+        return frames
+
+
+def encode_response(status: int | Status, body: bytes = b"") -> bytes:
+    return struct.pack("<H", _u16(int(status), "status")) + body
+
+
+def decode_response(frame: Frame) -> tuple[int, bytes]:
+    if not frame.flags & FrameFlag.RESPONSE:
+        raise SetProtocolError("кадр не является ответом")
+    if len(frame.payload) < 2:
+        raise SetProtocolError("ответ не содержит status")
+    return int.from_bytes(frame.payload[:2], "little"), frame.payload[2:]
+
+
+DEVICE_INFO_SCHEMA_VERSION = 1
+DEVICE_INFO_FIXED_SIZE = 25
+DEVICE_MODEL_MAX = 63
+CAPABILITIES_SCHEMA_VERSION = 1
+CAPABILITIES_SIZE = 20
+
+
+@dataclass(frozen=True)
+class DeviceInfo:
+    """Канонический body ответа DEVICE_INFO, без двухбайтового status."""
+
+    device_class: int
+    hardware_version: int
+    firmware_version: int
+    dictionary_version: int
+    serial_number: int
+    model: str
+    schema_version: int = DEVICE_INFO_SCHEMA_VERSION
+
+    def encode(self) -> bytes:
+        _u16(self.schema_version, "schema_version")
+        if self.schema_version != DEVICE_INFO_SCHEMA_VERSION:
+            raise SetProtocolError("неподдерживаемая схема DEVICE_INFO")
+        _u16(self.device_class, "device_class")
+        _u32(self.hardware_version, "hardware_version")
+        _u32(self.firmware_version, "firmware_version")
+        _u32(self.dictionary_version, "dictionary_version")
+        if not 0 <= self.serial_number <= 0xFFFFFFFFFFFFFFFF:
+            raise SetProtocolError("serial_number вне диапазона u64")
+        model = self.model.encode("utf-8")
+        if len(model) > DEVICE_MODEL_MAX:
+            raise SetProtocolError("model длиннее 63 байт UTF-8")
+        return struct.pack(
+            "<HHIIIQB",
+            self.schema_version,
+            self.device_class,
+            self.hardware_version,
+            self.firmware_version,
+            self.dictionary_version,
+            self.serial_number,
+            len(model),
+        ) + model
+
+    @classmethod
+    def decode(cls, payload: bytes) -> "DeviceInfo":
+        if len(payload) < DEVICE_INFO_FIXED_SIZE:
+            raise SetProtocolError("DEVICE_INFO короче фиксированного заголовка")
+        values = struct.unpack_from("<HHIIIQB", payload)
+        model_length = values[-1]
+        if values[0] != DEVICE_INFO_SCHEMA_VERSION:
+            raise SetProtocolError(f"неподдерживаемая схема DEVICE_INFO {values[0]}")
+        if model_length > DEVICE_MODEL_MAX or len(payload) != DEVICE_INFO_FIXED_SIZE + model_length:
+            raise SetProtocolError("DEVICE_INFO содержит неверную длину model")
+        try:
+            model = payload[DEVICE_INFO_FIXED_SIZE:].decode("utf-8")
+        except UnicodeDecodeError as error:
+            raise SetProtocolError("DEVICE_INFO model не является UTF-8") from error
+        return cls(
+            device_class=values[1],
+            hardware_version=values[2],
+            firmware_version=values[3],
+            dictionary_version=values[4],
+            serial_number=values[5],
+            model=model,
+            schema_version=values[0],
+        )
+
+
+@dataclass(frozen=True)
+class Capabilities:
+    """Канонический body ответа CAPABILITIES, без status."""
+
+    max_payload: int
+    interface_mask: int
+    feature_flags: int
+    max_read_items: int
+    max_write_items: int
+    max_subscriptions: int
+    max_publish_items: int
+    schema_version: int = CAPABILITIES_SCHEMA_VERSION
+
+    def encode(self) -> bytes:
+        if self.schema_version != CAPABILITIES_SCHEMA_VERSION:
+            raise SetProtocolError("неподдерживаемая схема CAPABILITIES")
+        if not 1 <= self.max_payload <= MAX_PAYLOAD_SIZE:
+            raise SetProtocolError("max_payload вне базового профиля")
+        _u32(self.interface_mask, "interface_mask")
+        _u32(self.feature_flags, "feature_flags")
+        for name in (
+            "max_read_items", "max_write_items", "max_subscriptions",
+            "max_publish_items",
+        ):
+            _u16(getattr(self, name), name)
+        return struct.pack(
+            "<HHIIHHHH",
+            self.schema_version,
+            self.max_payload,
+            self.interface_mask,
+            self.feature_flags,
+            self.max_read_items,
+            self.max_write_items,
+            self.max_subscriptions,
+            self.max_publish_items,
+        )
+
+    @classmethod
+    def decode(cls, payload: bytes) -> "Capabilities":
+        if len(payload) != CAPABILITIES_SIZE:
+            raise SetProtocolError("CAPABILITIES должен содержать ровно 20 байт")
+        values = struct.unpack("<HHIIHHHH", payload)
+        result = cls(
+            max_payload=values[1],
+            interface_mask=values[2],
+            feature_flags=values[3],
+            max_read_items=values[4],
+            max_write_items=values[5],
+            max_subscriptions=values[6],
+            max_publish_items=values[7],
+            schema_version=values[0],
+        )
+        # Каноническая повторная кодировка выполняет все проверки диапазонов.
+        result.encode()
+        return result
+
+    @property
+    def interfaces(self) -> tuple[Interface, ...]:
+        return tuple(
+            interface for interface in Interface
+            if interface is not Interface.NONE and self.interface_mask & (1 << interface)
+        )
+
+    @property
+    def features(self) -> Feature:
+        return Feature(self.feature_flags)
+
+
+FW_BEGIN_FIXED_SIZE = 58
+FW_DATA_HEADER_SIZE = 12
+FW_END_SIZE = 40
+
+
+@dataclass(frozen=True)
+class FirmwareBegin:
+    image_size: int
+    image_crc32: int
+    image_version: int
+    base_address: int
+    slot: int
+    block_size: int
+    sha256: bytes
+    flags: FirmwareFlag = FirmwareFlag(0)
+    signing_key_id: int = 0
+    signature: bytes = b""
+
+    def encode(self) -> bytes:
+        _u32(self.image_size, "image_size")
+        _u32(self.image_crc32, "image_crc32")
+        _u32(self.image_version, "image_version")
+        _u32(self.base_address, "base_address")
+        _u32(self.signing_key_id, "signing_key_id")
+        if not 0 <= self.slot <= 0xFF:
+            raise SetProtocolError("slot вне диапазона u8")
+        if not 1 <= self.block_size <= MAX_PAYLOAD_SIZE - FW_DATA_HEADER_SIZE:
+            raise SetProtocolError("block_size не помещается в FW_DATA")
+        if len(self.sha256) != 32:
+            raise SetProtocolError("SHA-256 должен содержать 32 байта")
+        if self.flags & FirmwareFlag.SIGNED and not self.signature:
+            raise SetProtocolError("SIGNED требует подпись")
+        _u16(len(self.signature), "signature_length")
+        payload = struct.pack(
+            "<IIIIBBH32sIH",
+            self.image_size,
+            self.image_crc32,
+            self.image_version,
+            self.base_address,
+            self.slot,
+            int(self.flags),
+            self.block_size,
+            self.sha256,
+            self.signing_key_id,
+            len(self.signature),
+        ) + self.signature
+        if len(payload) > MAX_PAYLOAD_SIZE:
+            raise SetProtocolError("FW_BEGIN не помещается в payload")
+        return payload
+
+    @classmethod
+    def decode(cls, payload: bytes) -> "FirmwareBegin":
+        if len(payload) < FW_BEGIN_FIXED_SIZE:
+            raise SetProtocolError("FW_BEGIN короче фиксированного заголовка")
+        values = struct.unpack_from("<IIIIBBH32sIH", payload)
+        signature_length = values[-1]
+        if len(payload) != FW_BEGIN_FIXED_SIZE + signature_length:
+            raise SetProtocolError("FW_BEGIN содержит неверную длину подписи")
+        result = cls(
+            image_size=values[0],
+            image_crc32=values[1],
+            image_version=values[2],
+            base_address=values[3],
+            slot=values[4],
+            flags=FirmwareFlag(values[5]),
+            block_size=values[6],
+            sha256=values[7],
+            signing_key_id=values[8],
+            signature=payload[FW_BEGIN_FIXED_SIZE:],
+        )
+        # Повторная кодировка выполняет все семантические проверки.
+        result.encode()
+        return result
+
+
+def firmware_manifest(begin: FirmwareBegin) -> bytes:
+    """Канонические байты, которые подписывает поставщик прошивки."""
+    return b"SETPFW2\0" + struct.pack(
+        "<IIIIB32s",
+        begin.image_size,
+        begin.image_crc32,
+        begin.image_version,
+        begin.base_address,
+        begin.slot,
+        begin.sha256,
+    )
+
+
+def firmware_begin_for_image(
+    image: bytes,
+    *,
+    image_version: int,
+    base_address: int,
+    slot: int,
+    block_size: int = 480,
+) -> FirmwareBegin:
+    return FirmwareBegin(
+        image_size=len(image),
+        image_crc32=crc32_ieee(image),
+        image_version=image_version,
+        base_address=base_address,
+        slot=slot,
+        block_size=block_size,
+        sha256=hashlib.sha256(image).digest(),
+        flags=FirmwareFlag.RESUME,
+    )
+
+
+def encode_firmware_data(offset: int, data: bytes, flags: int = 0) -> bytes:
+    _u32(offset, "offset")
+    _u16(flags, "flags")
+    if not data or len(data) > MAX_PAYLOAD_SIZE - FW_DATA_HEADER_SIZE:
+        raise SetProtocolError("неверный размер блока FW_DATA")
+    return struct.pack("<IHHI", offset, len(data), flags, crc32_ieee(data)) + data
+
+
+def decode_firmware_data(payload: bytes) -> tuple[int, int, bytes]:
+    if len(payload) < FW_DATA_HEADER_SIZE:
+        raise SetProtocolError("FW_DATA короче заголовка")
+    offset, length, flags, expected_crc = struct.unpack_from("<IHHI", payload)
+    data = payload[FW_DATA_HEADER_SIZE:]
+    if not data or len(data) != length:
+        raise SetProtocolError("FW_DATA содержит неверную длину блока")
+    if crc32_ieee(data) != expected_crc:
+        raise SetProtocolError("FW_DATA содержит неверный CRC блока")
+    return offset, flags, data
+
+
+def encode_subscribe(subscription_id: int, period_ms: int, addresses: Iterable[int]) -> bytes:
+    items = tuple(addresses)
+    _u16(subscription_id, "subscription_id")
+    _u32(period_ms, "period_ms")
+    _u16(len(items), "address_count")
+    for address in items:
+        _u32(address, "address")
+    payload = struct.pack("<HIH", subscription_id, period_ms, len(items))
+    payload += b"".join(struct.pack("<I", address) for address in items)
+    if len(payload) > MAX_PAYLOAD_SIZE:
+        raise SetProtocolError("SUBSCRIBE не помещается в payload")
+    return payload
+
+
+def decode_subscribe(payload: bytes) -> tuple[int, int, tuple[int, ...]]:
+    if len(payload) < 8:
+        raise SetProtocolError("SUBSCRIBE короче заголовка")
+    subscription_id, period_ms, count = struct.unpack_from("<HIH", payload)
+    if len(payload) != 8 + count * 4:
+        raise SetProtocolError("SUBSCRIBE содержит неверное число адресов")
+    addresses = struct.unpack_from(f"<{count}I", payload, 8) if count else ()
+    return subscription_id, period_ms, tuple(addresses)
+
+
+@dataclass(frozen=True)
+class PublishItem:
+    address: int
+    encoding: ValueEncoding
+    element_count: int
+    data: bytes
+
+
+def encode_publish(
+    subscription_id: int,
+    sample_sequence: int,
+    timestamp_ms: int,
+    items: Iterable[PublishItem],
+) -> bytes:
+    values = tuple(items)
+    _u16(subscription_id, "subscription_id")
+    _u16(sample_sequence, "sample_sequence")
+    _u32(timestamp_ms, "timestamp_ms")
+    _u16(len(values), "item_count")
+    chunks = [struct.pack("<HHIH", subscription_id, sample_sequence, timestamp_ms, len(values))]
+    for item in values:
+        _u32(item.address, "address")
+        if not 1 <= item.element_count <= 0xFF:
+            raise SetProtocolError("element_count вне диапазона 1..255")
+        if not item.data or len(item.data) > 0xFFFF:
+            raise SetProtocolError("элемент PUBLISH не содержит данные")
+        chunks.append(
+            struct.pack(
+                "<IBBH",
+                item.address,
+                int(item.encoding),
+                item.element_count,
+                len(item.data),
+            )
+            + item.data
+        )
+    payload = b"".join(chunks)
+    if len(payload) > MAX_PAYLOAD_SIZE:
+        raise SetProtocolError("PUBLISH не помещается в один payload")
+    return payload
+
+
+def decode_publish(payload: bytes) -> tuple[int, int, int, tuple[PublishItem, ...]]:
+    if len(payload) < 10:
+        raise SetProtocolError("PUBLISH короче заголовка")
+    subscription_id, sample_sequence, timestamp_ms, count = struct.unpack_from(
+        "<HHIH", payload
+    )
+    offset = 10
+    items: list[PublishItem] = []
+    for _ in range(count):
+        if offset + 8 > len(payload):
+            raise SetProtocolError("PUBLISH обрывается в заголовке элемента")
+        address, encoding, element_count, data_length = struct.unpack_from(
+            "<IBBH", payload, offset
+        )
+        offset += 8
+        if not element_count or not data_length or offset + data_length > len(payload):
+            raise SetProtocolError("PUBLISH содержит повреждённый элемент")
+        try:
+            value_encoding = ValueEncoding(encoding)
+        except ValueError as error:
+            raise SetProtocolError(f"неизвестный encoding {encoding}") from error
+        items.append(
+            PublishItem(
+                address=address,
+                encoding=value_encoding,
+                element_count=element_count,
+                data=payload[offset : offset + data_length],
+            )
+        )
+        offset += data_length
+    if offset != len(payload):
+        raise SetProtocolError("PUBLISH содержит хвост после элементов")
+    return subscription_id, sample_sequence, timestamp_ms, tuple(items)