vignette/apps/api/app/engine_client.py

"""엔진 게이트웨이 HTTP 클라이언트.

⚠️ 게이트웨이 자체(apps/api/engine_gateway/)는 람다가 직접 만든다. 여기는 *호출부*만.
게이트웨이가 provider 라우팅(claude_cli/claude_api/codex_cli/agy_cli/openai/solar)·
모델 탐색·캐싱·상주 claude -p 풀을 흡수한다(마스터플랜 §0, R1).
이 백엔드는 ENGINE_URL로 HTTP 호출만 한다.

계약 (람다와 합의할 게이트웨이 API):
  POST {ENGINE_URL}/v1/generate         — 단발 생성 (평가 deep-loop 등)
  POST {ENGINE_URL}/v1/stream           — SSE 토큰 스트림 (내담자 AI 응답)
  GET  {ENGINE_URL}/v1/capabilities     — provider별 사용 가능 모델·추론 강도
  GET  {ENGINE_URL}/health

요청 바디는 3-AI 역할별 system 레이어(L0~L6, 설계서 §1.2)를 게이트웨이에 넘기되,
text 는 *PII 마스킹 후(text_masked)* 만 보낸다 (R7/F-03, 마스킹은 호출 전 가드레일이 완료).
"""

from __future__ import annotations

import asyncio
from typing import Any, AsyncIterator, Optional

import httpx

from .config import settings
from .contracts.engine_gateway import (
    AIRole as AIRole,
    EngineCapabilitiesResponse,
    EngineMessage as EngineMessage,
    EngineGatewaySseLineDecoder,
    EngineGatewaySsePacket,
    EngineProvider,
    GenerateRequest,
    GenerateResponse,
    ReasoningEffort,
    StreamRequest,
    normalize_engine_gateway_model,
)


class EngineError(RuntimeError):
    """게이트웨이 호출 실패. 라우트가 503/502 로 변환."""


class EngineClient:
    """ENGINE_URL 게이트웨이 비동기 클라이언트. 앱 수명주기 동안 1 인스턴스 재사용."""

    def __init__(
        self,
        base_url: Optional[str] = None,
        *,
        shared_secret: Optional[str] = None,
    ) -> None:
        self.base_url = (base_url or settings.engine_url).rstrip("/")
        configured_secret = settings.engine_gateway_shared_secret.get_secret_value()
        self._shared_secret = (
            configured_secret if shared_secret is None else shared_secret
        ).strip()
        self.engine_mode = settings.engine_mode
        self.live_client_provider: Optional[EngineProvider] = settings.live_client_provider
        self.default_model: Optional[str] = None
        self.default_reasoning_effort: Optional[ReasoningEffort] = None
        self._client: Optional[httpx.AsyncClient] = None
        self._lock = asyncio.Lock()

    async def startup(self) -> None:
        async with self._lock:
            if self._client is None:
                self._client = self._new_client()

    def _new_client(self) -> httpx.AsyncClient:
        return httpx.AsyncClient(
            base_url=self.base_url,
            headers=self._auth_headers(),
            timeout=httpx.Timeout(
                settings.engine_timeout,
                connect=settings.engine_connect_timeout,
            ),
        )

    def _auth_headers(self) -> dict[str, str]:
        if not self._shared_secret:
            return {}
        return {"X-Vignette-Engine-Token": self._shared_secret}

    async def shutdown(self) -> None:
        async with self._lock:
            if self._client is not None:
                await self._client.aclose()
                self._client = None

    async def configure(
        self,
        *,
        base_url: str,
        engine_mode: EngineProvider,
        default_model: Optional[str] = None,
        default_reasoning_effort: Optional[ReasoningEffort] = None,
    ) -> None:
        next_url = base_url.rstrip("/")
        next_model = normalize_engine_gateway_model(default_model)
        async with self._lock:
            url_changed = next_url != self.base_url
            self.base_url = next_url
            self.engine_mode = engine_mode
            self.default_model = next_model
            self.default_reasoning_effort = default_reasoning_effort
            if self._client is not None and url_changed:
                old_client = self._client
                self._client = self._new_client()
                await old_client.aclose()

    def _payload(self, req: GenerateRequest) -> dict[str, Any]:
        payload = req.model_dump(exclude_none=True)
        provider = self.engine_mode
        if req.ai_role == "client" and req.session_id and self.live_client_provider:
            provider = self.live_client_provider
        if "provider" not in payload:
            payload["provider"] = provider
        # 관리자 기본 모델/추론 강도는 그 provider에 속한 값이다. 실시간 lane이
        # 다른 provider면 잘못된 모델 slug를 넘기지 않고 해당 provider 기본값을 쓴다.
        same_provider = payload["provider"] == self.engine_mode
        if same_provider and self.default_model and "model" not in payload:
            payload["model"] = self.default_model
        if (
            same_provider
            and self.default_reasoning_effort
            and "reasoning_effort" not in payload
        ):
            payload["reasoning_effort"] = self.default_reasoning_effort
        return payload

    @property
    def client(self) -> httpx.AsyncClient:
        if self._client is None:
            raise EngineError("EngineClient not started — call startup() in lifespan")
        return self._client

    async def health(self) -> bool:
        return bool((await self.health_detail()).get("ok"))

    async def health_detail(self) -> dict[str, Any]:
        try:
            params: dict[str, str] = {"provider": self.engine_mode}
            if self.default_model:
                params["model"] = self.default_model
            if self.default_reasoning_effort:
                params["reasoning_effort"] = self.default_reasoning_effort
            r = await self.client.get("/ready", params=params)
            if r.status_code == 404:
                live = await self.client.get("/health")
                return {
                    "ok": live.status_code == 200,
                    "detail": "gateway liveness only; readiness endpoint unavailable",
                    "status_code": live.status_code,
                }
            payload: dict[str, Any] = {}
            try:
                payload = r.json()
            except ValueError:
                payload = {}
            return {
                "ok": r.status_code == 200 and bool(payload.get("ok", False)),
                "detail": str(payload.get("detail") or r.text or "engine readiness failed"),
                "status_code": r.status_code,
                "cached": bool(payload.get("cached", False)),
            }
        except httpx.HTTPError as exc:
            return {
                "ok": False,
                "detail": f"engine readiness transport error: {exc}",
                "status_code": None,
            }

    async def capabilities(
        self,
        *,
        provider: EngineProvider,
        base_url: str | None = None,
        force: bool = False,
    ) -> EngineCapabilitiesResponse:
        target_url = (base_url or self.base_url).rstrip("/")
        params = {"provider": provider, "force": str(force).lower()}
        try:
            if target_url == self.base_url:
                response = await self.client.get("/v1/capabilities", params=params)
            else:
                async with httpx.AsyncClient(
                    base_url=target_url,
                    headers=self._auth_headers(),
                    timeout=httpx.Timeout(30, connect=settings.engine_connect_timeout),
                ) as client:
                    response = await client.get("/v1/capabilities", params=params)
            response.raise_for_status()
            return EngineCapabilitiesResponse.model_validate(response.json())
        except httpx.HTTPStatusError as exc:
            raise EngineError(
                f"engine capabilities {exc.response.status_code}: {exc.response.text}"
            ) from exc
        except (httpx.HTTPError, ValueError) as exc:
            raise EngineError(f"engine capabilities unavailable: {exc}") from exc

    async def generate(
        self,
        req: GenerateRequest,
        *,
        timeout: float | None = None,
    ) -> GenerateResponse:
        """단발 생성."""
        try:
            kwargs: dict[str, Any] = {}
            if timeout is not None:
                kwargs["timeout"] = timeout
            r = await self.client.post(
                "/v1/generate",
                json=self._payload(req),
                **kwargs,
            )
            r.raise_for_status()
        except httpx.HTTPStatusError as e:
            raise EngineError(f"engine generate {e.response.status_code}: {e.response.text}") from e
        except httpx.HTTPError as e:
            raise EngineError(f"engine generate transport error: {e}") from e
        return GenerateResponse.model_validate(r.json())

    async def stream(self, req: StreamRequest) -> AsyncIterator[str]:
        """SSE 토큰 스트림 프록시.

        게이트웨이 SSE(`text/event-stream`) 의 원시 non-empty line을 yield한다.
        새 호출부는 raw line 대신 `stream_packets()`를 사용한다.
        """
        try:
            async with self.client.stream(
                "POST", "/v1/stream", json=self._payload(req)
            ) as r:
                r.raise_for_status()
                async for line in r.aiter_lines():
                    if line:
                        yield line
        except httpx.HTTPStatusError as e:
            raise EngineError(f"engine stream {e.response.status_code}") from e
        except httpx.HTTPError as e:
            raise EngineError(f"engine stream transport error: {e}") from e

    async def stream_packets(self, req: StreamRequest) -> AsyncIterator[EngineGatewaySsePacket]:
        """Decode gateway SSE into the shared token/done/error contract.

        Keep wire-format parsing at the gateway client boundary so app services
        do not depend on raw SSE line structure. A future Node.js gateway should
        only need to preserve `app.contracts.engine_gateway`.
        """
        decoder = EngineGatewaySseLineDecoder()
        async for raw in self.stream(req):
            packet = decoder.feed_line(raw)
            if packet is not None:
                yield packet

    async def close_session(self, session_id: str) -> bool:
        """회기 종료 시 게이트웨이의 상주 페르소나 프로세스를 회수한다."""
        if not session_id:
            return False
        try:
            response = await self.client.delete(f"/session/{session_id}")
            response.raise_for_status()
            return bool(response.json().get("closed"))
        except (httpx.HTTPError, ValueError):
            # DB 회기 종료 성공을 게이트웨이 정리 실패 때문에 되돌리지는 않는다.
            return False


# 앱 전역 싱글톤 (main lifespan 에서 startup/shutdown)
engine_client = EngineClient()