user-engine/src/user_engine/web.py

"""Dependency-free WSGI transport for the user-engine portal.

Authentication is deliberately delegated to KeyCape (or another OIDC-aware
edge).  The application accepts claims only when the edge presents a shared
authentication marker configured at process start.  This keeps passwords,
MFA material, provider administration credentials, and browser sessions out
of user-engine.
"""

from __future__ import annotations

from dataclasses import asdict, is_dataclass
from enum import Enum
from html import escape
import json
import secrets
from typing import Any, Callable, Iterable, Mapping
from urllib.parse import parse_qs, urlencode

from user_engine.domain import AccountStatus
from user_engine.errors import AuthorizationDenied, ConflictError, NotFoundError, ValidationError
from user_engine.oidc import OIDCClient, cookie_value
from user_engine.ports import IdentityProvisioningPort, ProvisioningRequest
from user_engine.service import UserEngineService

StartResponse = Callable[[str, list[tuple[str, str]]], Any]


def _jsonable(value: Any) -> Any:
    if is_dataclass(value):
        return {key: _jsonable(item) for key, item in asdict(value).items()}
    if isinstance(value, Enum):
        return value.value
    if isinstance(value, Mapping):
        return {str(key): _jsonable(item) for key, item in value.items()}
    if isinstance(value, (tuple, list)):
        return [_jsonable(item) for item in value]
    if hasattr(value, "isoformat"):
        return value.isoformat()
    return value


class PortalApplication:
    """Small, auditable HTTP adapter over :class:`UserEngineService`."""

    def __init__(
        self,
        service: UserEngineService,
        *,
        trusted_proxy_secret: str,
        login_url: str,
        public_registration: bool = True,
        oidc_client: OIDCClient | None = None,
        provisioning: IdentityProvisioningPort | None = None,
    ) -> None:
        if len(trusted_proxy_secret) < 24:
            raise ValueError("trusted proxy secret must contain at least 24 characters")
        self.service = service
        self.trusted_proxy_secret = trusted_proxy_secret
        self.login_url = login_url
        self.public_registration = public_registration
        self.oidc_client = oidc_client
        self.provisioning = provisioning

    def __call__(self, environ: Mapping[str, Any], start_response: StartResponse) -> Iterable[bytes]:
        correlation_id = environ.get("HTTP_X_REQUEST_ID") or f"corr_{secrets.token_hex(12)}"
        try:
            return self._dispatch(environ, start_response, str(correlation_id))
        except (ValidationError, ConflictError, ValueError) as exc:
            return self._error(start_response, "400 Bad Request", "invalid_request", str(exc), correlation_id)
        except RuntimeError:
            return self._error(
                start_response,
                "502 Bad Gateway",
                "provisioning_unavailable",
                "Identity provisioning is temporarily unavailable.",
                correlation_id,
            )
        except AuthorizationDenied:
            return self._error(start_response, "403 Forbidden", "access_denied", "Access denied.", correlation_id)
        except NotFoundError:
            return self._error(start_response, "404 Not Found", "not_found", "Resource not found.", correlation_id)
        except (json.JSONDecodeError, UnicodeDecodeError):
            return self._error(start_response, "400 Bad Request", "invalid_json", "Malformed request body.", correlation_id)

    def _dispatch(self, environ: Mapping[str, Any], start_response: StartResponse, correlation_id: str) -> Iterable[bytes]:
        method = str(environ.get("REQUEST_METHOD", "GET")).upper()
        path = str(environ.get("PATH_INFO", "/")).rstrip("/") or "/"
        if path == "/healthz":
            return self._json(start_response, "200 OK", _jsonable(self.service.health()), correlation_id)
        if path == "/readyz":
            report = self.service.readiness()
            return self._json(start_response, "200 OK" if report.ready else "503 Service Unavailable", _jsonable(report), correlation_id)
        if path == "/metrics":
            supplied = str(environ.get("HTTP_X_USER_ENGINE_PROXY_SECRET", ""))
            if not secrets.compare_digest(supplied, self.trusted_proxy_secret):
                raise AuthorizationDenied("metrics require the trusted workload marker")
            return self._metrics(start_response, correlation_id)
        if path in {"/login", "/oidc/start"}:
            location = self.oidc_client.begin() if self.oidc_client else self.login_url
            start_response("303 See Other", [("Location", location), *self._security_headers(correlation_id)])
            return [b""]
        if path == "/oidc/callback":
            if self.oidc_client is None:
                raise NotFoundError("OIDC login is not configured")
            query = parse_qs(str(environ.get("QUERY_STRING", "")))
            if query.get("error"):
                raise AuthorizationDenied("OIDC login failed")
            session_id = self.oidc_client.complete(
                code=query.get("code", [""])[0],
                state=query.get("state", [""])[0],
            )
            headers = [
                ("Location", "/"),
                ("Set-Cookie", f"ue_session={session_id}; Path=/; HttpOnly; Secure; SameSite=Lax; Max-Age=3600"),
                *self._security_headers(correlation_id),
            ]
            start_response("303 See Other", headers)
            return [b""]
        if path == "/logout" and method == "POST":
            session_id = cookie_value(str(environ.get("HTTP_COOKIE", "")), "ue_session")
            if session_id and self.oidc_client:
                self.oidc_client.logout(session_id)
            start_response(
                "303 See Other",
                [("Location", "/"), ("Set-Cookie", "ue_session=; Path=/; HttpOnly; Secure; SameSite=Lax; Max-Age=0"), *self._security_headers(correlation_id)],
            )
            return [b""]
        if path == "/" and method == "GET":
            actor = self._optional_actor(environ)
            return self._html(start_response, self._home(actor), correlation_id)

        actor = self._actor(environ)
        if path == "/api/v1/me" and method == "GET":
            return self._json(start_response, "200 OK", _jsonable(self.service.me(self._claims(environ), correlation_id=correlation_id)), correlation_id)
        if path == "/api/v1/registrations" and method == "POST":
            if not self.public_registration:
                raise AuthorizationDenied("public registration disabled")
            body = self._body(environ)
            session = self.service.start_registration(
                actor,
                tenant=body.get("tenant"),
                correlation_id=correlation_id,
            )
            return self._json(start_response, "201 Created", _jsonable(session), correlation_id)
        if path.startswith("/api/v1/registrations/") and path.endswith("/complete") and method == "POST":
            registration_id = path.split("/")[4]
            body = self._body(environ)
            result = self.service.complete_registration(
                actor,
                registration_id,
                display_name=body.get("display_name"),
                primary_email=body.get("primary_email"),
                correlation_id=correlation_id,
            )
            return self._json(start_response, "200 OK", _jsonable(result), correlation_id)
        if path.startswith("/api/v1/tenants/") and path.endswith("/users") and method == "GET":
            tenant = path.split("/")[4]
            self.service.resolve_tenant_context(actor, tenant)
            memberships = self.service.store.memberships_for_tenant(tenant)
            offset, limit = self._page(environ)
            items = memberships[offset : offset + limit]
            payload = {"items": _jsonable(items), "offset": offset, "limit": limit, "total": len(memberships)}
            return self._json(start_response, "200 OK", payload, correlation_id)
        if path.startswith("/api/v1/tenants/") and path.endswith("/users") and method == "POST":
            tenant = path.split("/")[4]
            self.service.resolve_tenant_context(actor, tenant)
            body = self._body(environ)
            user = self.service.create_user(
                actor,
                display_name=body.get("display_name"),
                primary_email=body.get("primary_email"),
                correlation_id=correlation_id,
            )
            # Platform operators may create an identity for a tenant other than
            # their own.  Ensure the lifecycle record follows the requested
            # tenant instead of only retaining the actor tenant created by the
            # generic domain operation.
            tenant_account = self.service.set_tenant_account_status(
                actor,
                user.user_id,
                AccountStatus.ACTIVE,
                tenant=tenant,
                correlation_id=correlation_id,
            )
            membership = self.service.add_membership(
                actor,
                user.user_id,
                tenant=tenant,
                scope_type="tenant",
                scope_id=tenant,
                kind=str(body.get("role", "user")),
                correlation_id=correlation_id,
            )
            return self._json(start_response, "201 Created", {
                "user": _jsonable(user),
                "tenant_account": _jsonable(tenant_account),
                "membership": _jsonable(membership),
                "provisioning_status": "pending",
            }, correlation_id)
        if path.startswith("/api/v1/tenants/") and path.endswith("/provision") and method == "POST":
            if self.provisioning is None:
                raise ValidationError("identity provisioning is unavailable")
            parts = path.split("/")
            tenant, user_id = parts[4], parts[6]
            self.service.resolve_tenant_context(actor, tenant)
            user = self.service.store.user(user_id)
            if user is None:
                raise NotFoundError("user not found")
            idempotency_key = str(environ.get("HTTP_IDEMPOTENCY_KEY", ""))
            if len(idempotency_key) < 16:
                raise ValidationError("Idempotency-Key must contain at least 16 characters")
            result = self.provisioning.provision(ProvisioningRequest(
                user_id=user.user_id,
                tenant=tenant,
                primary_email=user.primary_email,
                display_name=user.display_name,
                idempotency_key=idempotency_key,
                correlation_id=correlation_id,
                roles=tuple(
                    membership.kind
                    for membership in self.service.store.memberships_for_user(
                        user.user_id, tenant=tenant
                    )
                ),
            ))
            identity = self.service.link_identity(
                actor,
                user.user_id,
                issuer="urn:netkingdom:directory",
                subject=result.external_subject,
                provider=result.provider,
                correlation_id=correlation_id,
            )
            return self._json(start_response, "200 OK", {
                "provisioning": _jsonable(result),
                "identity": _jsonable(identity),
            }, correlation_id)
        if path.startswith("/api/v1/tenants/") and "/users/" in path and method == "PATCH":
            parts = path.split("/")
            tenant, user_id = parts[4], parts[6]
            body = self._body(environ)
            status = AccountStatus(str(body["status"]))
            idempotency_key = str(environ.get("HTTP_IDEMPOTENCY_KEY", ""))
            if len(idempotency_key) < 16:
                raise ValidationError("Idempotency-Key must contain at least 16 characters")
            result = self._change_status(
                actor, tenant, user_id, status,
                idempotency_key=idempotency_key,
                correlation_id=correlation_id,
            )
            return self._json(start_response, "200 OK", _jsonable(result), correlation_id)
        if path.startswith("/admin/") and method == "GET":
            tenant = path.split("/")[2]
            self.service.resolve_tenant_context(actor, tenant)
            memberships = self.service.store.memberships_for_tenant(tenant)
            return self._html(
                start_response,
                self._admin(tenant, memberships, self._csrf_token(environ)),
                correlation_id,
            )
        if path.startswith("/admin/") and method == "POST":
            parts = path.split("/")
            tenant = parts[2]
            self.service.resolve_tenant_context(actor, tenant)
            body = self._form_body(environ)
            self._require_csrf(environ, str(body.get("csrf_token", "")))
            if len(parts) == 4 and parts[3] == "users":
                user = self.service.create_user(
                    actor,
                    display_name=body.get("display_name"),
                    primary_email=body.get("primary_email"),
                    correlation_id=correlation_id,
                )
                self.service.set_tenant_account_status(
                    actor, user.user_id, AccountStatus.ACTIVE,
                    tenant=tenant, correlation_id=correlation_id,
                )
                self.service.add_membership(
                    actor, user.user_id, tenant=tenant, scope_type="tenant",
                    scope_id=tenant, kind=str(body.get("role", "user")),
                    correlation_id=correlation_id,
                )
                return self._redirect(start_response, f"/admin/{tenant}", correlation_id)
            if len(parts) == 6 and parts[3] == "users" and parts[5] == "provision":
                if self.provisioning is None:
                    raise ValidationError("identity provisioning is unavailable")
                user_id = parts[4]
                user = self.service.store.user(user_id)
                if user is None:
                    raise NotFoundError("user not found")
                result = self.provisioning.provision(ProvisioningRequest(
                    user_id=user.user_id,
                    tenant=tenant,
                    primary_email=user.primary_email,
                    display_name=user.display_name,
                    idempotency_key=f"portal-{user.user_id}-{tenant}",
                    correlation_id=correlation_id,
                    roles=tuple(
                        item.kind for item in self.service.store.memberships_for_user(
                            user.user_id, tenant=tenant
                        )
                    ),
                ))
                self.service.link_identity(
                    actor, user.user_id, issuer="urn:netkingdom:directory",
                    subject=result.external_subject, provider=result.provider,
                    correlation_id=correlation_id,
                )
                if result.password_setup_url:
                    return self._html(
                        start_response,
                        self._password_setup_handoff(
                            result.password_setup_url, tenant
                        ),
                        correlation_id,
                    )
                query = urlencode({"provisioned": user.user_id, "status": result.status})
                return self._redirect(start_response, f"/admin/{tenant}?{query}", correlation_id)
            if len(parts) == 6 and parts[3] == "users" and parts[5] == "status":
                status = AccountStatus(str(body.get("status", "")))
                if status not in {AccountStatus.ACTIVE, AccountStatus.SUSPENDED}:
                    raise ValidationError("browser lifecycle supports active or suspended")
                self._change_status(
                    actor, tenant, parts[4], status,
                    idempotency_key=f"portal-status-{parts[4]}-{status.value}",
                    correlation_id=correlation_id,
                )
                return self._redirect(start_response, f"/admin/{tenant}", correlation_id)
        return self._error(start_response, "404 Not Found", "not_found", "Resource not found.", correlation_id)

    def _change_status(
        self,
        actor: Any,
        tenant: str,
        user_id: str,
        status: AccountStatus,
        *,
        idempotency_key: str,
        correlation_id: str,
    ) -> Any:
        if self.provisioning is None:
            raise ValidationError("identity provisioning is unavailable")
        self.service.resolve_tenant_context(actor, tenant)
        identity = next(
            (
                item for item in self.service.store.identities_for_user(user_id)
                if item.provider == "netkingdom-lldap"
            ),
            None,
        )
        if identity is None:
            raise ValidationError("user has no managed login identity")
        if status == AccountStatus.SUSPENDED:
            self.provisioning.suspend(
                external_subject=identity.subject,
                idempotency_key=idempotency_key,
                correlation_id=correlation_id,
            )
        elif status == AccountStatus.ACTIVE:
            self.provisioning.reactivate(
                external_subject=identity.subject,
                idempotency_key=idempotency_key,
                correlation_id=correlation_id,
            )
        else:
            raise ValidationError("provider lifecycle supports active or suspended")
        return self.service.set_tenant_account_status(
            actor, user_id, status, tenant=tenant, correlation_id=correlation_id
        )

    def _claims(self, environ: Mapping[str, Any]) -> Mapping[str, Any]:
        if self.oidc_client is not None:
            session_id = cookie_value(str(environ.get("HTTP_COOKIE", "")), "ue_session")
            if session_id:
                claims = self.oidc_client.claims(session_id)
                if claims is not None:
                    return claims
        marker = str(environ.get("HTTP_X_USER_ENGINE_PROXY_SECRET", ""))
        if not secrets.compare_digest(marker, self.trusted_proxy_secret):
            raise AuthorizationDenied("untrusted identity source")
        raw = environ.get("HTTP_X_VERIFIED_OIDC_CLAIMS")
        if not raw:
            raise AuthorizationDenied("verified claims required")
        claims = json.loads(str(raw))
        if not isinstance(claims, dict):
            raise AuthorizationDenied("verified claims must be an object")
        return claims

    def _actor(self, environ: Mapping[str, Any]) -> Any:
        return self.service.identity_adapter.normalize(self._claims(environ))

    def _optional_actor(self, environ: Mapping[str, Any]) -> Any | None:
        try:
            return self._actor(environ)
        except (AuthorizationDenied, json.JSONDecodeError, ValidationError):
            return None

    @staticmethod
    def _body(environ: Mapping[str, Any]) -> Mapping[str, Any]:
        length = min(int(environ.get("CONTENT_LENGTH") or 0), 65536)
        payload = environ["wsgi.input"].read(length) if length else b"{}"
        value = json.loads(payload.decode("utf-8"))
        if not isinstance(value, dict):
            raise ValidationError("request body must be an object")
        return value

    @staticmethod
    def _form_body(environ: Mapping[str, Any]) -> Mapping[str, str]:
        content_type = str(environ.get("CONTENT_TYPE", "")).partition(";")[0]
        if content_type != "application/x-www-form-urlencoded":
            raise ValidationError("form content type is required")
        length = min(int(environ.get("CONTENT_LENGTH") or 0), 65536)
        payload = environ["wsgi.input"].read(length).decode("utf-8")
        return {key: values[0] for key, values in parse_qs(payload).items()}

    def _csrf_token(self, environ: Mapping[str, Any]) -> str:
        if self.oidc_client is None:
            raise AuthorizationDenied("browser session required")
        session_id = cookie_value(str(environ.get("HTTP_COOKIE", "")), "ue_session")
        token = self.oidc_client.csrf_token(session_id or "")
        if token is None:
            raise AuthorizationDenied("browser session required")
        return token

    def _require_csrf(self, environ: Mapping[str, Any], supplied: str) -> None:
        expected = self._csrf_token(environ)
        if not supplied or not secrets.compare_digest(supplied, expected):
            raise AuthorizationDenied("invalid CSRF token")

    @staticmethod
    def _page(environ: Mapping[str, Any]) -> tuple[int, int]:
        query = parse_qs(str(environ.get("QUERY_STRING", "")))
        offset = max(0, int(query.get("offset", ["0"])[0]))
        limit = max(1, min(100, int(query.get("limit", ["25"])[0])))
        return offset, limit

    def _home(self, actor: Any | None) -> str:
        identity = (
            f"<p>Signed in as <strong>{escape(actor.preferred_username)}</strong>.</p>"
            if actor is not None
            else f'<p><a class="button" href="/login">Sign in with KeyCape</a></p>'
        )
        return self._page_html(
            "Identity & access",
            "<h1>Your account, on your terms.</h1>"
            "<p>Join a tenant, complete onboarding, and manage access without exposing credentials to applications.</p>"
            + identity,
        )

    def _admin(self, tenant: str, memberships: tuple[Any, ...], csrf_token: str) -> str:
        rows = "".join(
            self._admin_row(tenant, item, csrf_token)
            for item in memberships
        ) or '<tr><td colspan="6">No members yet.</td></tr>'
        return self._page_html(
            f"{tenant} users",
            f"""<h1>{escape(tenant)} users</h1>
<section><h2>Add a user</h2>
<form method="post" action="/admin/{escape(tenant)}/users">
<input type="hidden" name="csrf_token" value="{escape(csrf_token)}">
<label>Display name <input name="display_name" required autocomplete="name"></label>
<label>Email <input name="primary_email" type="email" required autocomplete="email"></label>
<label>Role <select name="role"><option value="user">User</option><option value="tenant-admin">Tenant administrator</option></select></label>
<button type="submit">Add user</button></form></section>
<section><h2>Members</h2><table><thead><tr><th>User</th><th>Email</th><th>Role</th><th>Status</th><th>Directory</th><th>Action</th></tr></thead><tbody>{rows}</tbody></table></section>""",
        )

    def _admin_row(self, tenant: str, membership: Any, csrf_token: str) -> str:
        user = self.service.store.user(membership.user_id)
        identities = self.service.store.identities_for_user(membership.user_id)
        directory = next(
            (item for item in identities if item.provider == "netkingdom-lldap"),
            None,
        )
        tenant_account = self.service.store.tenant_account(tenant, membership.user_id)
        status = tenant_account.status if tenant_account else AccountStatus.INVITED
        action = (
            f"""<span>Linked as {escape(directory.subject)}</span>
<form method="post" action="/admin/{escape(tenant)}/users/{escape(membership.user_id)}/provision">
<input type="hidden" name="csrf_token" value="{escape(csrf_token)}">
<button type="submit">Create password setup link</button></form>
<form method="post" action="/admin/{escape(tenant)}/users/{escape(membership.user_id)}/status">
<input type="hidden" name="csrf_token" value="{escape(csrf_token)}">
<input type="hidden" name="status" value="{'active' if status == AccountStatus.SUSPENDED else 'suspended'}">
<button type="submit">{'Reactivate' if status == AccountStatus.SUSPENDED else 'Suspend'}</button></form>"""
            if directory
            else f"""<form method="post" action="/admin/{escape(tenant)}/users/{escape(membership.user_id)}/provision">
<input type="hidden" name="csrf_token" value="{escape(csrf_token)}">
<button type="submit">Create login</button></form>"""
        )
        return (
            f"<tr><td>{escape(user.display_name or membership.user_id) if user else escape(membership.user_id)}</td>"
            f"<td>{escape(user.primary_email or '') if user else ''}</td>"
            f"<td>{escape(membership.kind)}</td>"
            f"<td>{escape(status.value)}</td>"
            f"<td>{'linked' if directory else 'pending'}</td><td>{action}</td></tr>"
        )

    def _password_setup_handoff(self, setup_url: str, tenant: str) -> str:
        if not setup_url.startswith("https://"):
            raise ValidationError("password setup handoff must use HTTPS")
        return self._page_html(
            "Password setup",
            "<h1>Login identity created</h1>"
            "<p>The password is handled only by the NetKingdom identity "
            "surface. This short-lived link is single use.</p>"
            f'<p><a class="button" rel="noreferrer" href="{escape(setup_url)}">'
            "Continue to password setup</a></p>"
            f'<p><a href="/admin/{escape(tenant)}">'
            "Return to tenant administration</a></p>",
        )

    def _redirect(self, start_response: StartResponse, location: str, correlation_id: str) -> list[bytes]:
        start_response("303 See Other", [("Location", location), *self._security_headers(correlation_id)])
        return [b""]

    @staticmethod
    def _page_html(title: str, body: str) -> str:
        return f"""<!doctype html><html lang="en"><head><meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>{escape(title)} · Railiance</title><style>
:root{{--ink:#17201c;--paper:#f5f1e8;--accent:#195b47;--line:#c8c1b3}}
*{{box-sizing:border-box}}body{{margin:0;background:var(--paper);color:var(--ink);font:18px/1.55 system-ui,sans-serif}}
header,main{{max-width:68rem;margin:auto;padding:1.25rem}}header{{border-bottom:1px solid var(--line)}}
h1{{font:clamp(2.2rem,7vw,5.5rem)/.98 Georgia,serif;max-width:13ch}}a{{color:var(--accent)}}
.button{{display:inline-block;background:var(--accent);color:white;padding:.8rem 1.15rem;border-radius:.3rem;text-decoration:none}}
table{{width:100%;border-collapse:collapse;background:#fff}}th,td{{padding:.75rem;text-align:left;border-bottom:1px solid var(--line)}}
section{{margin:2rem 0}}form{{display:grid;gap:.8rem;max-width:42rem}}label{{display:grid;gap:.25rem}}
input,select,button{{font:inherit;padding:.65rem}}button{{background:var(--accent);color:white;border:0;border-radius:.3rem;cursor:pointer}}
a:focus-visible,input:focus-visible,select:focus-visible,button:focus-visible{{outline:3px solid #e59f24;outline-offset:3px}}@media(max-width:640px){{body{{font-size:16px}}table{{display:block;overflow-x:auto}}}}
</style></head><body><header><strong>Railiance identity</strong></header><main>{body}</main></body></html>"""

    def _html(self, start_response: StartResponse, body: str, correlation_id: str) -> list[bytes]:
        data = body.encode()
        start_response("200 OK", [("Content-Type", "text/html; charset=utf-8"), ("Content-Length", str(len(data))), *self._security_headers(correlation_id)])
        return [data]

    def _json(self, start_response: StartResponse, status: str, payload: Any, correlation_id: str) -> list[bytes]:
        data = json.dumps(payload, separators=(",", ":"), default=str).encode()
        start_response(status, [("Content-Type", "application/json"), ("Content-Length", str(len(data))), *self._security_headers(correlation_id)])
        return [data]

    def _metrics(
        self, start_response: StartResponse, correlation_id: str
    ) -> list[bytes]:
        report = self.service.readiness()
        counts = self.service.operability_snapshot().metrics
        lines = [
            "# HELP user_engine_ready Whether runtime dependencies are ready.",
            "# TYPE user_engine_ready gauge",
            f"user_engine_ready {1 if report.ready else 0}",
            "# HELP user_engine_records Durable logical record counts by kind.",
            "# TYPE user_engine_records gauge",
        ]
        for kind, count in sorted(counts.items()):
            safe_kind = "".join(
                character for character in str(kind)
                if character.isalnum() or character in "_-"
            )
            lines.append(f'user_engine_records{{kind="{safe_kind}"}} {int(count)}')
        data = ("\n".join(lines) + "\n").encode()
        start_response(
            "200 OK",
            [
                ("Content-Type", "text/plain; version=0.0.4; charset=utf-8"),
                ("Content-Length", str(len(data))),
                *self._security_headers(correlation_id),
            ],
        )
        return [data]

    def _error(self, start_response: StartResponse, status: str, code: str, message: str, correlation_id: str) -> list[bytes]:
        return self._json(start_response, status, {"error": {"code": code, "message": message, "correlation_id": correlation_id}}, correlation_id)

    @staticmethod
    def _security_headers(correlation_id: str) -> list[tuple[str, str]]:
        return [
            ("X-Request-ID", correlation_id),
            ("Cache-Control", "no-store"),
            ("X-Content-Type-Options", "nosniff"),
            ("Referrer-Policy", "no-referrer"),
            ("Content-Security-Policy", "default-src 'none'; style-src 'unsafe-inline'; form-action 'self'; frame-ancestors 'none'; base-uri 'none'"),
        ]