feat(gateway): add core gateway protocol implementation

新建了完整的网关协议模块，包含版本协商、基础类型定义、信道请求模型、错误码规范、通信帧结构以及握手流程，实现了完整的客户端-服务端通信协议基础框架

backend/package/yuxi/gateway/__init__.py

@@ -0,0 +1,39 @@
+from yuxi.gateway.protocol import (
+    ChannelLogoutRequest,
+    ChannelStartRequest,
+    ChannelStatusRequest,
+    ConnectParams,
+    ErrorCode,
+    ErrorDetail,
+    EventFrame,
+    GatewayFrame,
+    HelloFeatures,
+    HelloOk,
+    NonEmptyString,
+    PositiveInt,
+    PROTOCOL_VERSION,
+    RequestFrame,
+    ResponseFrame,
+    handle_handshake,
+    negotiate_version,
+)
+
+__all__ = [
+    "RequestFrame",
+    "ResponseFrame",
+    "EventFrame",
+    "GatewayFrame",
+    "ErrorCode",
+    "ErrorDetail",
+    "PROTOCOL_VERSION",
+    "negotiate_version",
+    "ConnectParams",
+    "HelloFeatures",
+    "HelloOk",
+    "handle_handshake",
+    "NonEmptyString",
+    "PositiveInt",
+    "ChannelStatusRequest",
+    "ChannelStartRequest",
+    "ChannelLogoutRequest",
+]

backend/package/yuxi/gateway/protocol/__init__.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+from typing import Annotated
+
+from pydantic import Field
+
+from yuxi.gateway.protocol.channels import ChannelLogoutRequest, ChannelStartRequest, ChannelStatusRequest
+from yuxi.gateway.protocol.errors import ErrorCode, ErrorDetail
+from yuxi.gateway.protocol.frames import EventFrame, RequestFrame, ResponseFrame
+from yuxi.gateway.protocol.handshake import ConnectParams, HelloFeatures, HelloOk, handle_handshake
+from yuxi.gateway.protocol.primitives import NonEmptyString, PositiveInt
+from yuxi.gateway.protocol.version import PROTOCOL_VERSION, negotiate_version
+
+GatewayFrame = Annotated[
+    RequestFrame | ResponseFrame | EventFrame,
+    Field(discriminator="type"),
+]
+
+__all__ = [
+    "RequestFrame",
+    "ResponseFrame",
+    "EventFrame",
+    "GatewayFrame",
+    "ErrorCode",
+    "ErrorDetail",
+    "PROTOCOL_VERSION",
+    "negotiate_version",
+    "ConnectParams",
+    "HelloFeatures",
+    "HelloOk",
+    "handle_handshake",
+    "NonEmptyString",
+    "PositiveInt",
+    "ChannelStatusRequest",
+    "ChannelStartRequest",
+    "ChannelLogoutRequest",
+]

backend/package/yuxi/gateway/protocol/channels.py

@@ -0,0 +1,19 @@
+from __future__ import annotations
+
+from pydantic import BaseModel
+
+
+class ChannelStatusRequest(BaseModel):
+    channel_id: str | None = None
+    account_id: str | None = None
+
+
+class ChannelStartRequest(BaseModel):
+    channel_id: str
+    account_id: str | None = None
+
+
+class ChannelLogoutRequest(BaseModel):
+    channel_id: str
+    account_id: str | None = None
+    logged_out: bool = True

backend/package/yuxi/gateway/protocol/errors.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from enum import IntEnum
+
+from pydantic import BaseModel
+
+
+class ErrorCode(IntEnum):
+    INVALID_REQUEST = -32600
+    METHOD_NOT_FOUND = -32601
+    INVALID_PARAMS = -32602
+    INTERNAL_ERROR = -32603
+    RATE_LIMITED = -32000
+    AUTH_REQUIRED = -32001
+    NOT_LINKED = -32002
+    NOT_PAIRED = -32003
+    AGENT_TIMEOUT = -32004
+    APPROVAL_NOT_FOUND = -32005
+    UNAVAILABLE = -32006
+
+
+class ErrorDetail(BaseModel):
+    code: ErrorCode
+    message: str
+    details: str | None = None
+    retryable: bool = False
+    retry_after_ms: int | None = None

backend/package/yuxi/gateway/protocol/frames.py

@@ -0,0 +1,36 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any, Literal
+
+from pydantic import BaseModel, Field
+
+if TYPE_CHECKING:
+    from yuxi.gateway.protocol.errors import ErrorDetail
+
+
+class RequestFrame(BaseModel):
+    type: Literal["req"] = "req"
+    id: str
+    method: str
+    params: dict[str, Any] = Field(default_factory=dict)
+
+
+class ResponseFrame(BaseModel):
+    type: Literal["res"] = "res"
+    id: str
+    ok: bool
+    payload: Any = None
+    error: ErrorDetail | None = None
+
+
+class EventFrame(BaseModel):
+    type: Literal["event"] = "event"
+    event: str
+    payload: Any = None
+    seq: int = 0
+    state_version: int = 0
+
+
+from yuxi.gateway.protocol.errors import ErrorDetail  # noqa: E402
+
+ResponseFrame.model_rebuild()

backend/package/yuxi/gateway/protocol/handshake.py

@@ -0,0 +1,75 @@
+from __future__ import annotations
+
+import uuid
+from typing import Literal
+
+from pydantic import BaseModel, Field
+
+from yuxi.gateway.protocol.version import negotiate_version
+
+
+class ConnectParams(BaseModel):
+    min_protocol: int = 1
+    max_protocol: int = 1
+    client_id: str = ""
+    client_version: str = ""
+    client_platform: str = ""
+    auth_token: str | None = None
+    caps: list[str] = Field(default_factory=list)
+
+    client_display_name: str = ""
+    client_device_family: str = ""
+    client_model_identifier: str = ""
+    client_mode: str = "default"
+    client_instance_id: str = ""
+
+    commands: list[str] = Field(default_factory=list)
+    permissions: dict[str, bool] = Field(default_factory=dict)
+
+    path_env: str = ""
+    role: str = ""
+    scopes: list[str] = Field(default_factory=list)
+
+    locale: str = ""
+    user_agent: str = ""
+
+
+class HelloFeatures(BaseModel):
+    methods: list[str] = Field(default_factory=list)
+    events: list[str] = Field(default_factory=list)
+
+
+class HelloOk(BaseModel):
+    type: Literal["hello-ok"] = "hello-ok"
+    protocol: int
+    server_version: str
+    server_id: str
+    session_id: str
+    features: HelloFeatures = Field(default_factory=HelloFeatures)
+    snapshot: dict | None = None
+    dm_policy: str = "pairing"
+    group_policy: str = "allowlist"
+    conn_id: str = ""
+    max_payload: int = 1048576
+    max_buffered_bytes: int = 10485760
+    tick_interval_ms: int = 5000
+
+
+async def handle_handshake(params: ConnectParams) -> HelloOk:
+    protocol = negotiate_version(params.min_protocol, params.max_protocol)
+    if protocol is None:
+        raise ValueError("Protocol version negotiation failed")
+
+    session_id = str(uuid.uuid4())
+    conn_id = f"conn-{session_id[:8]}"
+    return HelloOk(
+        protocol=protocol,
+        server_version="1.0.0",
+        server_id="forcepilot-gateway",
+        session_id=session_id,
+        conn_id=conn_id,
+        features=HelloFeatures(
+            methods=["channel.status", "channel.start", "channel.stop", "chat.send", "chat.abort"],
+            events=["channel.status_change", "tick", "chat", "channel.logout", "config.reload"],
+        ),
+    )

backend/package/yuxi/gateway/protocol/primitives.py

@@ -0,0 +1,14 @@
+from __future__ import annotations
+
+from typing import Annotated
+
+from pydantic import AfterValidator, StringConstraints
+
+NonEmptyString = Annotated[str, StringConstraints(min_length=1)]
+
+
+def _ensure_positive(v: int) -> int:
+    return v if v >= 1 else 1
+
+
+PositiveInt = Annotated[int, AfterValidator(_ensure_positive)]

backend/package/yuxi/gateway/protocol/version.py

@@ -0,0 +1,13 @@
+from __future__ import annotations
+
+PROTOCOL_VERSION: int = 1
+
+
+def negotiate_version(client_min: int, client_max: int) -> int | None:
+    server_max = PROTOCOL_VERSION
+    server_min = 1
+
+    negotiated = min(client_max, server_max)
+    if negotiated >= max(client_min, server_min):
+        return negotiated
+    return None