deer-flow/backend/app/gateway/auth_middleware.py

"""Global authentication middleware — fail-closed safety net.

Rejects unauthenticated requests to non-public paths with 401. When a
request passes the cookie check, resolves the JWT payload to a real
``User`` object and stamps it into both ``request.state.user`` and the
``deerflow.runtime.user_context`` contextvar so that repository-layer
owner filtering works automatically via the sentinel pattern.

Fine-grained permission checks remain in authz.py decorators.
"""

from collections.abc import Callable

from fastapi import Request, Response
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.responses import JSONResponse
from starlette.types import ASGIApp

from app.gateway.auth.errors import AuthErrorCode
from deerflow.runtime.user_context import reset_current_user, set_current_user

# Paths that never require authentication.
_PUBLIC_PATH_PREFIXES: tuple[str, ...] = (
    "/health",
    "/docs",
    "/redoc",
    "/openapi.json",
)

# Exact auth paths that are public (login/register/status check).
# /api/v1/auth/me, /api/v1/auth/change-password etc. are NOT public.
_PUBLIC_EXACT_PATHS: frozenset[str] = frozenset(
    {
        "/api/v1/auth/login/local",
        "/api/v1/auth/register",
        "/api/v1/auth/logout",
        "/api/v1/auth/setup-status",
    }
)


def _is_public(path: str) -> bool:
    stripped = path.rstrip("/")
    if stripped in _PUBLIC_EXACT_PATHS:
        return True
    return any(path.startswith(prefix) for prefix in _PUBLIC_PATH_PREFIXES)


class AuthMiddleware(BaseHTTPMiddleware):
    """Coarse-grained auth gate: reject requests without a valid session cookie.

    This does NOT verify JWT signature or user existence — that is the job of
    ``get_current_user_from_request`` in deps.py (called by ``@require_auth``).
    The middleware only checks *presence* of the cookie so that new endpoints
    that forget ``@require_auth`` are not completely exposed.
    """

    def __init__(self, app: ASGIApp) -> None:
        super().__init__(app)

    async def dispatch(self, request: Request, call_next: Callable) -> Response:
        if _is_public(request.url.path):
            return await call_next(request)

        # Non-public path: require session cookie
        if not request.cookies.get("access_token"):
            return JSONResponse(
                status_code=401,
                content={
                    "detail": {
                        "code": AuthErrorCode.NOT_AUTHENTICATED,
                        "message": "Authentication required",
                    }
                },
            )

        # Resolve the full user now so repository-layer owner filters
        # can read from the contextvar. We use the "optional" flavour so
        # middleware never raises on bad tokens — the cookie-presence
        # check above plus the @require_auth decorator provide the
        # strict gates. A stale/invalid token yields user=None here;
        # the request continues without a contextvar, and any protected
        # endpoint will still be rejected by @require_auth.
        from app.gateway.deps import get_optional_user_from_request

        user = await get_optional_user_from_request(request)
        if user is None:
            return await call_next(request)

        request.state.user = user
        token = set_current_user(user)
        try:
            return await call_next(request)
        finally:
            reset_current_user(token)