atlas-iac/services/hermes/scripts/codex_broker.py

#!/usr/bin/env python3
"""Credential-isolating Codex Responses proxy for Hermes chat tenants."""

from __future__ import annotations

import base64
import binascii
import fcntl
import hmac
import json
import os
import tempfile
import time
from datetime import datetime, timezone
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from pathlib import Path
from typing import Any, Iterable

import httpx

from routing_catalog import load_catalog, resolve_route


HOST = os.environ.get("HERMES_CODEX_BROKER_LISTEN_HOST", "0.0.0.0")
PORT = int(os.environ.get("HERMES_CODEX_BROKER_LISTEN_PORT", "9003"))


def _relay_token() -> str:
    """Read relay auth without exporting it to Codex subprocesses."""
    path = Path(
        os.environ.get(
            "HERMES_CODEX_BROKER_KEY_FILE", "/runtime-access/chat-relay-key"
        )
    )
    try:
        return path.read_text(encoding="utf-8").strip()
    except OSError:
        return ""


TOKEN = _relay_token()
UPSTREAM = os.environ.get(
    "HERMES_CODEX_BROKER_UPSTREAM",
    "https://chatgpt.com/backend-api/codex",
).rstrip("/")
MAX_BODY_BYTES = int(os.environ.get("HERMES_CODEX_BROKER_MAX_BODY", str(64 << 20)))
MAX_RESPONSE_BYTES = int(
    os.environ.get("HERMES_CODEX_BROKER_MAX_RESPONSE", str(64 << 20))
)
READ_TIMEOUT_SECONDS = float(os.environ.get("HERMES_CODEX_BROKER_READ_TIMEOUT", "900"))
FALLBACK_ALLOWED_MODELS = {
    value.strip()
    for value in os.environ.get(
        "HERMES_CODEX_BROKER_MODELS",
        "gpt-5.6-luna,gpt-5.6-sol,gpt-5.6-terra",
    ).split(",")
    if value.strip()
}
ROUTED_MODEL_PREFIX = "route/codex/"
TOKEN_REFRESH_SKEW_SECONDS = int(
    os.environ.get("HERMES_CODEX_BROKER_REFRESH_SKEW_SECONDS", "300")
)
HEALTH_PATH = Path(
    os.environ.get("HERMES_CODEX_HEALTH_PATH", "/opt/data/provider-health/codex.json")
)


def _previous_health() -> dict[str, Any]:
    """Read the previous non-secret native transport health snapshot."""
    try:
        value = json.loads(HEALTH_PATH.read_text(encoding="utf-8"))
    except (OSError, TypeError, ValueError, json.JSONDecodeError):
        return {}
    return value if isinstance(value, dict) else {}


def _record_health(state: str, **updates: Any) -> None:
    """Atomically publish current first-party Codex health without credentials."""
    value = _previous_health()
    value.update(
        {
            "transport": "codex-chatgpt-subscription",
            "state": state,
            "checked_at": datetime.now(timezone.utc).isoformat(),
            "authenticated": state != "unavailable",
            **updates,
        }
    )
    try:
        HEALTH_PATH.parent.mkdir(parents=True, exist_ok=True)
        temporary = HEALTH_PATH.with_name(f".{HEALTH_PATH.name}.{os.getpid()}.tmp")
        temporary.write_text(
            json.dumps(value, indent=2, sort_keys=True) + "\n", encoding="utf-8"
        )
        os.replace(temporary, HEALTH_PATH)
    except OSError:
        pass


def _requested_effort(payload: dict[str, Any]) -> str:
    """Return the bounded Codex reasoning effort carried by a routed request."""
    reasoning = payload.get("reasoning")
    if isinstance(reasoning, dict) and reasoning.get("effort") in {
        "low",
        "medium",
        "high",
        "xhigh",
    }:
        return str(reasoning["effort"])
    return "medium"


def _real_model(model: str) -> str:
    """Translate a Switchyard effort-qualified target into a Codex model."""
    if model.startswith(ROUTED_MODEL_PREFIX):
        model = resolve_route(model)
    return model


def _authorized(header: str | None) -> bool:
    """Authenticate a tenant without exposing the relay secret."""
    if not TOKEN or not header or not header.startswith("Bearer "):
        return False
    return hmac.compare_digest(header[7:].strip(), TOKEN)


def _token_expiry(token: str) -> float:
    """Return a JWT expiry timestamp, or zero for an opaque token."""
    try:
        encoded = token.split(".")[1]
        encoded += "=" * (-len(encoded) % 4)
        return float(json.loads(base64.urlsafe_b64decode(encoded)).get("exp", 0))
    except (IndexError, ValueError, TypeError, json.JSONDecodeError, binascii.Error):
        return 0.0


def _write_codex_auth(path: Path, payload: dict[str, Any]) -> None:
    """Atomically persist refreshed first-party credentials for every CLI lane."""
    path.parent.mkdir(parents=True, exist_ok=True)
    fd, temporary = tempfile.mkstemp(prefix=".auth.", suffix=".json", dir=path.parent)
    try:
        with os.fdopen(fd, "w", encoding="utf-8") as stream:
            json.dump(payload, stream, separators=(",", ":"))
            stream.write("\n")
            stream.flush()
            os.fsync(stream.fileno())
        os.chmod(temporary, 0o600)
        os.replace(temporary, path)
    finally:
        try:
            os.unlink(temporary)
        except FileNotFoundError:
            pass


def _access_token(*, force_refresh: bool = False) -> str:
    """Return a live ChatGPT OAuth token, refreshing the canonical CLI store."""
    codex_home = Path(
        os.environ.get("CODEX_HOME", str(Path.home() / ".codex"))
    ).expanduser()
    auth_path = codex_home / "auth.json"
    lock_path = codex_home / "hermes-codex-broker.lock"
    codex_home.mkdir(parents=True, exist_ok=True)
    try:
        with lock_path.open("a+", encoding="utf-8") as lock:
            fcntl.flock(lock.fileno(), fcntl.LOCK_EX)
            payload = json.loads(auth_path.read_text(encoding="utf-8"))
            if not isinstance(payload, dict):
                raise RuntimeError("owner Codex authentication is invalid")
            tokens = payload.get("tokens") or {}
            if not isinstance(tokens, dict):
                raise RuntimeError("owner Codex authentication is invalid")
            token = str(tokens.get("access_token") or "").strip()
            if not token:
                raise RuntimeError("owner Codex access token is unavailable")
            expires_at = _token_expiry(token)
            should_refresh = force_refresh or (
                bool(expires_at)
                and expires_at <= time.time() + TOKEN_REFRESH_SKEW_SECONDS
            )
            if should_refresh:
                refresh_token = str(tokens.get("refresh_token") or "").strip()
                if not refresh_token:
                    raise RuntimeError("owner Codex refresh token is unavailable")
                # Use the same first-party ChatGPT OAuth refresh as Codex CLI.
                # This never introduces an OpenAI API key or metered billing.
                from hermes_cli.auth import refresh_codex_oauth_pure

                refreshed = refresh_codex_oauth_pure(
                    token,
                    refresh_token,
                    timeout_seconds=30.0,
                )
                tokens["access_token"] = refreshed["access_token"]
                tokens["refresh_token"] = refreshed.get(
                    "refresh_token", refresh_token
                )
                payload["tokens"] = tokens
                payload["last_refresh"] = refreshed.get("last_refresh")
                _write_codex_auth(auth_path, payload)
                token = str(tokens["access_token"]).strip()
            return token
    except RuntimeError:
        raise
    except (OSError, ValueError) as exc:
        raise RuntimeError("owner Codex authentication is unavailable") from exc


def _upstream_headers(token: str) -> dict[str, str]:
    """Build the first-party headers expected by the Codex backend."""
    from agent.auxiliary_client import _codex_cloudflare_headers

    headers = _codex_cloudflare_headers(token)
    headers.update(
        {
            "Accept": "text/event-stream",
            "Authorization": f"Bearer {token}",
            "Content-Type": "application/json",
        }
    )
    return headers


def _normalize_input_images(response_input: list[Any]) -> None:
    """Normalize Chat-Completions image parts for the Codex Responses API."""

    def image_url_value(part: dict[str, Any]) -> tuple[str | None, str | None]:
        """Return a Responses URL from URL-object or base64-source forms."""

        def search(candidate: Any, depth: int = 0) -> tuple[str | None, str | None]:
            if isinstance(candidate, str):
                if candidate.startswith(("data:image/", "https://", "http://")):
                    return candidate, None
                return None, None
            if not isinstance(candidate, dict) or depth > 4:
                return None, None
            detail = candidate.get("detail")
            url = candidate.get("url")
            if isinstance(url, str) and url.strip():
                return url, detail if isinstance(detail, str) else None
            data = candidate.get("data")
            media_type = candidate.get("media_type") or candidate.get("mime_type")
            if (
                isinstance(data, str)
                and data
                and isinstance(media_type, str)
                and media_type.startswith("image/")
                and all(character not in media_type for character in "\r\n;, ")
            ):
                return f"data:{media_type};base64,{data}", (
                    detail if isinstance(detail, str) else None
                )
            for nested in candidate.values():
                nested_url, nested_detail = search(nested, depth + 1)
                if nested_url:
                    return nested_url, (
                        detail if isinstance(detail, str) else nested_detail
                    )
            return None, None

        for candidate in (part.get("image_url"), part.get("source"), part):
            image_url, detail = search(candidate)
            if image_url:
                return image_url, detail
        return None, None

    def image_shape(part: dict[str, Any]) -> str:
        """Describe only structural types when an upstream image is malformed."""

        def describe(value: Any, depth: int = 0) -> Any:
            if depth > 3:
                return type(value).__name__
            if isinstance(value, dict):
                return {
                    str(key)[:40]: describe(nested, depth + 1)
                    for key, nested in list(value.items())[:12]
                }
            if isinstance(value, list):
                return [describe(nested, depth + 1) for nested in value[:4]]
            if isinstance(value, str):
                return f"str[{len(value)}]"
            return type(value).__name__

        return json.dumps(describe(part), sort_keys=True, separators=(",", ":"))

    for item in response_input:
        if not isinstance(item, dict):
            continue
        content = item.get("content")
        if not isinstance(content, list):
            continue
        for part in content:
            if not isinstance(part, dict) or part.get("type") not in {
                "image",
                "image_url",
                "input_image",
            }:
                continue
            image_url, detail = image_url_value(part)
            if isinstance(detail, str) and detail and "detail" not in part:
                part["detail"] = detail
            if not isinstance(image_url, str) or not image_url.strip():
                raise ValueError(
                    "non-empty Responses image URL required; shape="
                    + image_shape(part)
                )
            part["type"] = "input_image"
            part["image_url"] = image_url
            part.pop("source", None)


def _validate_payload(payload: Any) -> dict[str, Any]:
    """Allow only bounded Responses requests for the approved model catalog."""
    if not isinstance(payload, dict):
        raise ValueError("JSON object required")
    model = payload.get("model")
    if not isinstance(model, str):
        raise ValueError("unsupported Codex model")
    model = _real_model(model)
    if not model.startswith("gpt-"):
        raise ValueError("unsupported Codex model")
    payload["model"] = model
    response_input = payload.get("input")
    if isinstance(response_input, str):
        if not response_input.strip():
            raise ValueError("non-empty Responses input required")
        # Switchyard accepts OpenAI Chat Completions requests and translates
        # their final text to a scalar Responses input.  The first-party Codex
        # endpoint is stricter than the public Responses API and only accepts
        # a list of typed input items.
        payload["input"] = [
            {
                "type": "message",
                "role": "user",
                "content": [{"type": "input_text", "text": response_input}],
            }
        ]
    elif isinstance(response_input, dict):
        payload["input"] = [response_input]
    elif not isinstance(response_input, list) or not response_input:
        raise ValueError("non-empty Responses input list required")
    _normalize_input_images(payload["input"])
    # Switchyard uses ``max_output_tokens`` to bound the tiny classifier call,
    # but its Responses translation can also copy that internal option onto the
    # selected provider request.  The first-party subscription Codex endpoint
    # does not accept any of the public API token-budget aliases.  Let Codex use
    # its own response budget instead of turning a healthy fallback into a 400.
    for unsupported_key in (
        "max_output_tokens",
        "max_completion_tokens",
        "max_tokens",
        # The subscription Codex backend owns sampling.  OpenAI-compatible
        # clients may add these public API fields during a retry; forwarding
        # them turns an otherwise healthy fallback into HTTP 400.
        "temperature",
        "top_p",
        "frequency_penalty",
        "presence_penalty",
        "logprobs",
        "top_logprobs",
        "seed",
        "n",
        "stop",
    ):
        payload.pop(unsupported_key, None)
    # Tenant conversations must not enter the owner's server-side history.
    payload["store"] = False
    payload["stream"] = True
    return payload


def _completed_response(lines: Iterable[str]) -> dict[str, Any]:
    """Collapse a Codex SSE stream for a non-streaming Responses caller."""
    terminal_response: dict[str, Any] | None = None
    output_items: dict[int, dict[str, Any]] = {}
    function_argument_deltas: dict[str, list[str]] = {}
    completed_function_arguments: set[str] = set()
    upstream_error = ""

    def function_key(event: dict[str, Any]) -> str:
        """Identify one streamed function call without retaining its content."""
        item_id = str(event.get("item_id") or "").strip()
        if item_id:
            return item_id
        output_index = event.get("output_index")
        return f"output:{output_index}" if isinstance(output_index, int) else ""

    def validate_arguments(arguments: Any) -> None:
        """Reject an incomplete JSON object so Switchyard can fail over."""
        if not isinstance(arguments, str):
            raise RuntimeError("Codex returned malformed function arguments")
        try:
            parsed_arguments = json.loads(arguments)
        except (TypeError, ValueError, json.JSONDecodeError) as exc:
            raise RuntimeError(
                "Codex returned retryable malformed function arguments"
            ) from exc
        if not isinstance(parsed_arguments, dict):
            raise RuntimeError("Codex returned malformed function arguments")

    for line in lines:
        if not line.startswith("data:"):
            continue
        value = line[5:].strip()
        if not value or value == "[DONE]":
            continue
        try:
            event = json.loads(value)
        except (TypeError, ValueError, json.JSONDecodeError):
            continue
        if not isinstance(event, dict):
            continue
        event_type = str(event.get("type") or "")
        response = event.get("response")
        if event_type == "response.function_call_arguments.delta":
            key = function_key(event)
            delta = event.get("delta")
            if key and isinstance(delta, str):
                function_argument_deltas.setdefault(key, []).append(delta)
        elif event_type == "response.function_call_arguments.done":
            key = function_key(event)
            arguments = event.get("arguments")
            if not isinstance(arguments, str) and key:
                arguments = "".join(function_argument_deltas.get(key, []))
            validate_arguments(arguments)
            if key:
                completed_function_arguments.add(key)
        if event_type == "response.output_item.done":
            item = event.get("item")
            output_index = event.get("output_index")
            if isinstance(item, dict) and isinstance(output_index, int):
                output_items[output_index] = item
        if event_type in {
            "response.completed",
            "response.failed",
            "response.incomplete",
        } and isinstance(response, dict):
            terminal_response = response
        elif event_type == "error":
            error = event.get("error")
            if isinstance(error, dict):
                upstream_error = str(error.get("message") or error.get("type") or "")
            else:
                upstream_error = str(error or "")
    for key, deltas in function_argument_deltas.items():
        if key not in completed_function_arguments:
            validate_arguments("".join(deltas))
    if terminal_response is not None:
        status = str(terminal_response.get("status") or "").lower()
        if status != "completed":
            details = terminal_response.get("incomplete_details") or {}
            reason = (
                str(details.get("reason") or "")
                if isinstance(details, dict)
                else ""
            )
            raise RuntimeError(
                "Codex returned a retryable incomplete response"
                + (f": {reason}" if reason else "")
            )
        # The subscription Codex endpoint streams complete output items but
        # currently leaves the terminal response's output array empty.  Public
        # Responses clients, including Switchyard, expect those items there.
        if output_items and not terminal_response.get("output"):
            terminal_response["output"] = [
                output_items[index] for index in sorted(output_items)
            ]
        # A Responses stream can be marked ``completed`` even when a function
        # call was cut off at the provider's output boundary.  Passing that
        # downstream as HTTP 200 makes Hermes retry the same broken turn until
        # it emits the unhelpful "Response truncated" message.  Reject malformed
        # terminal tool calls here so Switchyard can fail over to another
        # eligible provider/model for this boundary.
        for item in terminal_response.get("output") or []:
            if not isinstance(item, dict) or item.get("type") != "function_call":
                continue
            if str(item.get("status") or "completed").lower() == "incomplete":
                raise RuntimeError("Codex returned a retryable incomplete tool call")
            arguments = item.get("arguments")
            validate_arguments(arguments)
        return terminal_response
    raise RuntimeError(upstream_error or "Codex stream ended without a terminal response")


def _normalized_stream(body: bytes, completed: dict[str, Any]) -> bytes:
    """Return Responses SSE with the reconstructed terminal response attached."""
    normalized: list[str] = []
    replaced_terminal = False
    pending_event_line = ""
    for line in body.decode("utf-8", errors="replace").splitlines():
        if line.startswith("event:"):
            pending_event_line = line
            continue
        if line.startswith("data:"):
            value = line[5:].strip()
            try:
                event = json.loads(value)
            except (TypeError, ValueError, json.JSONDecodeError):
                event = None
            event_type = event.get("type") if isinstance(event, dict) else ""
            item = event.get("item") if isinstance(event, dict) else None
            if event_type == "response.function_call_arguments.done" or (
                event_type == "response.output_item.done"
                and isinstance(item, dict)
                and item.get("type") == "function_call"
            ):
                # Switchyard translates each terminal function-call snapshot
                # into another Chat Completions argument delta.  Retain the
                # already-validated delta sequence, not its duplicate copies.
                pending_event_line = ""
                continue
            if isinstance(event, dict) and event_type == "response.completed":
                stream_completed = dict(completed)
                stream_completed["output"] = [
                    output_item
                    for output_item in stream_completed.get("output") or []
                    if not isinstance(output_item, dict)
                    or output_item.get("type") != "function_call"
                ]
                event["response"] = stream_completed
                line = "data: " + json.dumps(event, separators=(",", ":"))
                replaced_terminal = True
            if pending_event_line:
                normalized.append(pending_event_line)
                pending_event_line = ""
        elif pending_event_line and line:
            normalized.append(pending_event_line)
            pending_event_line = ""
        normalized.append(line)
    if pending_event_line:
        normalized.append(pending_event_line)
    if not replaced_terminal:
        raise RuntimeError("Codex stream ended without a completed event")
    # Preserve the blank event terminator required by SSE clients.  Responses
    # streams end at response.completed; they do not require a Chat
    # Completions-style [DONE] sentinel.
    return ("\n".join(normalized).rstrip("\n") + "\n\n").encode("utf-8")


class Handler(BaseHTTPRequestHandler):
    """Authenticated streaming proxy; request bodies and tokens are never logged."""

    server_version = "HermesCodexBroker/1"

    def _json(self, status: int, value: dict[str, Any]) -> None:
        body = json.dumps(value, separators=(",", ":")).encode("utf-8")
        self.send_response(status)
        self.send_header("Content-Type", "application/json")
        self.send_header("Content-Length", str(len(body)))
        self.send_header("Cache-Control", "no-store")
        self.end_headers()
        self.wfile.write(body)

    def _check_auth(self) -> bool:
        if _authorized(self.headers.get("Authorization")):
            return True
        self._json(401, {"error": {"message": "unauthorized", "type": "auth_error"}})
        return False

    def do_GET(self) -> None:  # noqa: N802 - BaseHTTPRequestHandler API
        if not self._check_auth():
            return
        if self.path == "/health":
            try:
                token = _access_token()
            except RuntimeError as exc:
                _record_health(
                    "unavailable",
                    authenticated=False,
                    last_error_at=datetime.now(timezone.utc).isoformat(),
                    error_type=type(exc).__name__,
                )
                self._json(503, {"ok": False, "error": str(exc)})
                return
            _record_health(
                "available",
                authenticated=True,
                token_expires_at=_token_expiry(token) or None,
            )
            self._json(200, {"ok": True, "provider": "openai-codex"})
            return
        if self.path in {"/models", "/v1/models"}:
            catalog = load_catalog()
            providers = catalog.get("providers", {}) if isinstance(catalog, dict) else {}
            codex = providers.get("codex", {}) if isinstance(providers, dict) else {}
            discovered = codex.get("models", []) if isinstance(codex, dict) else []
            models = {
                model for model in discovered if isinstance(model, str) and model.startswith("gpt-")
            } or FALLBACK_ALLOWED_MODELS
            self._json(
                200,
                {
                    "object": "list",
                    "data": [
                        {"id": model, "object": "model", "owned_by": "openai-codex"}
                        for model in sorted(models)
                    ],
                },
            )
            return
        self._json(404, {"error": {"message": "not found", "type": "not_found"}})

    def do_POST(self) -> None:  # noqa: N802 - BaseHTTPRequestHandler API
        if self.path not in {"/responses", "/v1/responses"}:
            self._json(404, {"error": {"message": "not found", "type": "not_found"}})
            return
        if not self._check_auth():
            return
        response_started = False
        try:
            length = int(self.headers.get("Content-Length", "0"))
        except ValueError:
            length = 0
        if length <= 0 or length > MAX_BODY_BYTES:
            self._json(413, {"error": {"message": "invalid request size", "type": "invalid_request_error"}})
            return

        try:
            payload = json.loads(self.rfile.read(length))
            requested_stream = payload.get("stream") is True
            payload = _validate_payload(payload)
            model = str(payload["model"])
            effort = _requested_effort(payload)
            started = time.monotonic()
            token = _access_token()
            timeout = httpx.Timeout(
                READ_TIMEOUT_SECONDS,
                connect=30.0,
                read=READ_TIMEOUT_SECONDS,
                write=60.0,
                pool=30.0,
            )
            with httpx.Client(timeout=timeout, headers=_upstream_headers(token)) as client:
                with client.stream("POST", f"{UPSTREAM}/responses", json=payload) as response:
                    if response.status_code >= 400:
                        body = response.read()
                        state = (
                            "capacity-limited"
                            if response.status_code == 429
                            else "unavailable"
                            if response.status_code in {401, 403}
                            else "degraded"
                        )
                        _record_health(
                            state,
                            last_error_at=datetime.now(timezone.utc).isoformat(),
                            status_code=response.status_code,
                            model=model,
                            effort=effort,
                        )
                        self.send_response(response.status_code)
                        self.send_header("Content-Type", response.headers.get("Content-Type", "application/json"))
                        self.send_header("Content-Length", str(len(body)))
                        self.send_header("Cache-Control", "no-store")
                        self.end_headers()
                        self.wfile.write(body)
                        return

                    # Validate the terminal Responses event before committing
                    # HTTP 200 downstream.  The Codex subscription endpoint can
                    # end a tool call with ``response.incomplete`` while still
                    # returning HTTP 200.  If that is streamed through, Hermes
                    # sees malformed JSON and eventually exposes "Response
                    # truncated" to the user.  Buffering one model boundary
                    # lets Switchyard receive a retryable 502 and choose another
                    # provider/model instead.  Tool execution remains streamed
                    # by Hermes after this short model boundary completes.
                    body = response.read()
                    if len(body) > MAX_RESPONSE_BYTES:
                        raise RuntimeError("Codex response exceeded broker limit")
                    completed = _completed_response(
                        body.decode("utf-8", errors="replace").splitlines()
                    )
                    _record_health(
                        "available",
                        last_success_at=datetime.now(timezone.utc).isoformat(),
                        latency_ms=int((time.monotonic() - started) * 1000),
                        model=model,
                        effort=effort,
                        token_expires_at=_token_expiry(token) or None,
                    )
                    if not requested_stream:
                        self._json(200, completed)
                        return

                    body = _normalized_stream(body, completed)

                    self.send_response(200)
                    self.send_header("Content-Type", "text/event-stream")
                    self.send_header("Content-Length", str(len(body)))
                    self.send_header("Cache-Control", "no-store")
                    self.send_header("X-Accel-Buffering", "no")
                    self.end_headers()
                    response_started = True
                    self.wfile.write(body)
                    self.wfile.flush()
        except ValueError as exc:
            self._json(400, {"error": {"message": str(exc), "type": "invalid_request_error"}})
        except (BrokenPipeError, ConnectionResetError):
            return
        except Exception as exc:
            if response_started:
                return
            _record_health(
                "degraded",
                last_error_at=datetime.now(timezone.utc).isoformat(),
                error_type=type(exc).__name__,
            )
            self._json(
                502,
                {
                    "error": {
                        "message": f"Codex broker failed: {type(exc).__name__}: {exc}",
                        "type": "upstream_error",
                    }
                },
            )

    def log_message(self, format: str, *args: Any) -> None:
        """Log only method/path/status metadata, never bodies or headers."""
        print(f"codex-broker {self.address_string()} {format % args}", flush=True)


def main() -> None:
    """Serve until Kubernetes terminates the sidecar."""
    if not TOKEN:
        raise SystemExit("runtime relay key is unavailable")
    try:
        token = _access_token()
    except RuntimeError as exc:
        _record_health(
            "unavailable",
            authenticated=False,
            last_error_at=datetime.now(timezone.utc).isoformat(),
            error_type=type(exc).__name__,
        )
    else:
        _record_health(
            "available",
            authenticated=True,
            token_expires_at=_token_expiry(token) or None,
        )
    ThreadingHTTPServer((HOST, PORT), Handler).serve_forever()


if __name__ == "__main__":
    main()