app.py

"""Bedrock AgentCore base implementation.

Provides a Starlette-based web server that wraps user functions as HTTP endpoints.
"""

import asyncio
import contextvars
import functools
import inspect
import json
import logging
import queue
import threading
import time
import uuid
from collections.abc import Sequence
from typing import Any, Callable, Dict, Optional

from starlette.applications import Starlette
from starlette.concurrency import run_in_threadpool
from starlette.exceptions import HTTPException
from starlette.middleware import Middleware
from starlette.responses import JSONResponse, Response, StreamingResponse
from starlette.routing import Route, WebSocketRoute
from starlette.types import Lifespan
from starlette.websockets import WebSocket, WebSocketDisconnect

from .context import BedrockAgentCoreContext, RequestContext
from .models import (
    ACCESS_TOKEN_HEADER,
    AUTHORIZATION_HEADER,
    CUSTOM_HEADER_PREFIX,
    OAUTH2_CALLBACK_URL_HEADER,
    REQUEST_ID_HEADER,
    SESSION_HEADER,
    TASK_ACTION_CLEAR_FORCED_STATUS,
    TASK_ACTION_FORCE_BUSY,
    TASK_ACTION_FORCE_HEALTHY,
    TASK_ACTION_JOB_STATUS,
    TASK_ACTION_PING_STATUS,
    PingStatus,
)
from .utils import convert_complex_objects


def _is_async_callable(obj: Any) -> bool:
    """Check if obj is async-callable, unwrapping functools.partial."""
    while isinstance(obj, functools.partial):
        obj = obj.func
    return asyncio.iscoroutinefunction(obj) or (callable(obj) and asyncio.iscoroutinefunction(obj.__call__))


def _is_async_gen_callable(obj: Any) -> bool:
    """Check if obj is an async generator function, unwrapping functools.partial."""
    while isinstance(obj, functools.partial):
        obj = obj.func
    return inspect.isasyncgenfunction(obj) or (callable(obj) and inspect.isasyncgenfunction(obj.__call__))


def _restore_context(ctx: contextvars.Context) -> None:
    """Restore context variables from a snapshot (Django asgiref pattern)."""
    for var, value in ctx.items():
        try:
            if var.get() != value:
                var.set(value)
        except LookupError:
            var.set(value)


class RequestContextFormatter(logging.Formatter):
    """Formatter including request and session IDs."""

    def format(self, record):
        """Format log record as AWS Lambda JSON."""
        import json
        from datetime import datetime

        log_entry = {
            "timestamp": datetime.utcnow().strftime("%Y-%m-%dT%H:%M:%S.%f")[:-3] + "Z",
            "level": record.levelname,
            "message": record.getMessage(),
            "logger": record.name,
        }

        request_id = BedrockAgentCoreContext.get_request_id()
        if request_id:
            log_entry["requestId"] = request_id

        session_id = BedrockAgentCoreContext.get_session_id()
        if session_id:
            log_entry["sessionId"] = session_id

        if record.exc_info:
            import traceback

            log_entry["errorType"] = record.exc_info[0].__name__
            log_entry["errorMessage"] = str(record.exc_info[1])
            log_entry["stackTrace"] = traceback.format_exception(*record.exc_info)
            log_entry["location"] = f"{record.pathname}:{record.funcName}:{record.lineno}"

        return json.dumps(log_entry, ensure_ascii=False)


class BedrockAgentCoreApp(Starlette):
    """Bedrock AgentCore application class that extends Starlette for AI agent deployment."""

    def __init__(
        self,
        debug: bool = False,
        lifespan: Optional[Lifespan] = None,
        middleware: Sequence[Middleware] | None = None,
    ):
        """Initialize Bedrock AgentCore application.

        Args:
            debug: Enable debug actions for task management (default: False)
            lifespan: Optional lifespan context manager for startup/shutdown
            middleware: Optional sequence of Starlette Middleware objects (or Middleware(...) entries)
        """
        self.handlers: Dict[str, Callable] = {}
        self._ping_handler: Optional[Callable] = None
        self._websocket_handler: Optional[Callable] = None
        self._active_tasks: Dict[int, Dict[str, Any]] = {}
        self._task_counter_lock: threading.Lock = threading.Lock()
        self._forced_ping_status: Optional[PingStatus] = None
        self._last_status_update_time: float = time.time()
        self._worker_loop: Optional[asyncio.AbstractEventLoop] = None
        self._worker_thread: Optional[threading.Thread] = None
        self._worker_loop_lock: threading.Lock = threading.Lock()

        routes = [
            Route("/invocations", self._handle_invocation, methods=["POST"]),
            Route("/ping", self._handle_ping, methods=["GET"]),
            WebSocketRoute("/ws", self._handle_websocket),
        ]
        super().__init__(routes=routes, lifespan=lifespan, middleware=middleware)
        self.debug = debug  # Set after super().__init__ to avoid override

        self.logger = logging.getLogger("bedrock_agentcore.app")
        if not self.logger.handlers:
            handler = logging.StreamHandler()
            formatter = RequestContextFormatter()
            handler.setFormatter(formatter)
            self.logger.addHandler(handler)
            self.logger.setLevel(logging.DEBUG if self.debug else logging.INFO)

    def entrypoint(self, func: Callable) -> Callable:
        """Decorator to register a function as the main entrypoint.

        Args:
            func: The function to register as entrypoint

        Returns:
            The decorated function with added serve method
        """
        self.handlers["main"] = func
        func.run = lambda port=8080, host=None: self.run(port, host)
        return func

    def ping(self, func: Callable) -> Callable:
        """Decorator to register a custom ping status handler.

        Args:
            func: The function to register as ping status handler

        Returns:
            The decorated function
        """
        self._ping_handler = func
        return func

    def websocket(self, func: Callable) -> Callable:
        """Decorator to register a WebSocket handler at /ws endpoint.

        Args:
            func: The function to register as WebSocket handler

        Returns:
            The decorated function

        Example:
            @app.websocket
            async def handler(websocket, context):
                await websocket.accept()
                # ... handle messages ...
        """
        self._websocket_handler = func
        return func

    def async_task(self, func: Callable) -> Callable:
        """Decorator to track async tasks for ping status.

        When a function is decorated with @async_task, it will:
        - Set ping status to HEALTHY_BUSY while running
        - Revert to HEALTHY when complete
        """
        if not _is_async_callable(func):
            raise ValueError("@async_task can only be applied to async functions")

        async def wrapper(*args, **kwargs):
            task_id = self.add_async_task(func.__name__)

            try:
                self.logger.debug("Starting async task: %s", func.__name__)
                start_time = time.time()
                result = await func(*args, **kwargs)
                duration = time.time() - start_time
                self.logger.info("Async task completed: %s (%.3fs)", func.__name__, duration)
                return result
            except Exception:
                duration = time.time() - start_time
                self.logger.exception("Async task failed: %s (%.3fs)", func.__name__, duration)
                raise
            finally:
                self.complete_async_task(task_id)

        wrapper.__name__ = func.__name__
        return wrapper

    def get_current_ping_status(self) -> PingStatus:
        """Get current ping status (forced > custom > automatic)."""
        current_status = None

        if self._forced_ping_status is not None:
            current_status = self._forced_ping_status
        elif self._ping_handler:
            try:
                result = self._ping_handler()
                if isinstance(result, str):
                    current_status = PingStatus(result)
                else:
                    current_status = result
            except Exception as e:
                self.logger.warning(
                    "Custom ping handler failed, falling back to automatic: %s: %s", type(e).__name__, e
                )

        if current_status is None:
            current_status = PingStatus.HEALTHY_BUSY if self._active_tasks else PingStatus.HEALTHY
        if not hasattr(self, "_last_known_status") or self._last_known_status != current_status:
            self._last_known_status = current_status
            self._last_status_update_time = time.time()

        return current_status

    def force_ping_status(self, status: PingStatus):
        """Force ping status to a specific value."""
        self._forced_ping_status = status

    def clear_forced_ping_status(self):
        """Clear forced status and resume automatic."""
        self._forced_ping_status = None

    def get_async_task_info(self) -> Dict[str, Any]:
        """Get info about running async tasks."""
        running_jobs = []
        for t in self._active_tasks.values():
            try:
                running_jobs.append(
                    {"name": t.get("name", "unknown"), "duration": time.time() - t.get("start_time", time.time())}
                )
            except Exception as e:
                self.logger.warning("Caught exception, continuing...: %s", e)
                continue

        return {"active_count": len(self._active_tasks), "running_jobs": running_jobs}

    def add_async_task(self, name: str, metadata: Optional[Dict] = None) -> int:
        """Register an async task for interactive health tracking.

        This method provides granular control over async task lifecycle,
        allowing developers to interactively start tracking tasks for health monitoring.
        Use this when you need precise control over when tasks begin and end.

        Args:
            name: Human-readable task name for monitoring
            metadata: Optional additional task metadata

        Returns:
            Task ID for tracking and completion

        Example:
            task_id = app.add_async_task("file_processing", {"file": "data.csv"})
            # ... do background work ...
            app.complete_async_task(task_id)
        """
        with self._task_counter_lock:
            task_id = hash(str(uuid.uuid4()))  # Generate truly unique hash-based ID

            # Register task start with same structure as @async_task decorator
            task_info = {"name": name, "start_time": time.time()}
            if metadata:
                task_info["metadata"] = metadata

            self._active_tasks[task_id] = task_info

        self.logger.info("Async task started: %s (ID: %s)", name, task_id)
        return task_id

    def complete_async_task(self, task_id: int) -> bool:
        """Mark an async task as complete for interactive health tracking.

        This method provides granular control over async task lifecycle,
        allowing developers to interactively complete tasks for health monitoring.
        Call this when your background work finishes.

        Args:
            task_id: Task ID returned from add_async_task

        Returns:
            True if task was found and completed, False otherwise

        Example:
            task_id = app.add_async_task("file_processing")
            # ... do background work ...
            completed = app.complete_async_task(task_id)
        """
        with self._task_counter_lock:
            task_info = self._active_tasks.pop(task_id, None)
            if task_info:
                task_name = task_info.get("name", "unknown")
                duration = time.time() - task_info.get("start_time", time.time())

                self.logger.info("Async task completed: %s (ID: %s, Duration: %.2fs)", task_name, task_id, duration)
                return True
            else:
                self.logger.warning("Attempted to complete unknown task ID: %s", task_id)
                return False

    def _build_request_context(self, request) -> RequestContext:
        """Build request context and setup all context variables."""
        try:
            headers = request.headers
            request_id = headers.get(REQUEST_ID_HEADER)
            if not request_id:
                request_id = str(uuid.uuid4())

            session_id = headers.get(SESSION_HEADER)
            BedrockAgentCoreContext.set_request_context(request_id, session_id)

            agent_identity_token = headers.get(ACCESS_TOKEN_HEADER)
            if agent_identity_token:
                BedrockAgentCoreContext.set_workload_access_token(agent_identity_token)

            oauth2_callback_url = headers.get(OAUTH2_CALLBACK_URL_HEADER)
            if oauth2_callback_url:
                BedrockAgentCoreContext.set_oauth2_callback_url(oauth2_callback_url)

            # Collect relevant request headers (Authorization + Custom headers)
            request_headers = {}

            # Add Authorization header if present
            authorization_header = headers.get(AUTHORIZATION_HEADER)
            if authorization_header is not None:
                request_headers[AUTHORIZATION_HEADER] = authorization_header

            # Add custom headers with the specified prefix
            for header_name, header_value in headers.items():
                if header_name.lower().startswith(CUSTOM_HEADER_PREFIX.lower()):
                    request_headers[header_name] = header_value

            # Set in context if any headers were found
            if request_headers:
                BedrockAgentCoreContext.set_request_headers(request_headers)

            # Get the headers from context to pass to RequestContext
            req_headers = BedrockAgentCoreContext.get_request_headers()

            return RequestContext(
                session_id=session_id,
                request_headers=req_headers,
                request=request,  # Pass through the Starlette request object
            )
        except Exception as e:
            self.logger.warning("Failed to build request context: %s: %s", type(e).__name__, e)
            request_id = str(uuid.uuid4())
            BedrockAgentCoreContext.set_request_context(request_id, None)
            return RequestContext(session_id=None, request=None)

    def _takes_context(self, handler: Callable) -> bool:
        try:
            params = list(inspect.signature(handler).parameters.keys())
            return len(params) >= 2 and params[1] == "context"
        except Exception:
            return False

    async def _handle_invocation(self, request):
        request_context = self._build_request_context(request)

        start_time = time.time()

        try:
            payload = await request.json()
            self.logger.debug("Processing invocation request")

            if self.debug:
                task_response = self._handle_task_action(payload)
                if task_response:
                    duration = time.time() - start_time
                    self.logger.info("Debug action completed (%.3fs)", duration)
                    return task_response

            handler = self.handlers.get("main")
            if not handler:
                self.logger.error("No entrypoint defined")
                return JSONResponse({"error": "No entrypoint defined"}, status_code=500)

            takes_context = self._takes_context(handler)

            handler_name = handler.__name__ if hasattr(handler, "__name__") else "unknown"
            self.logger.debug("Invoking handler: %s", handler_name)
            result = await self._invoke_handler(handler, request_context, takes_context, payload)

            duration = time.time() - start_time
            if inspect.isgenerator(result):
                self.logger.info("Returning streaming response (generator) (%.3fs)", duration)
                return StreamingResponse(self._sync_stream_with_error_handling(result), media_type="text/event-stream")
            elif inspect.isasyncgen(result):
                self.logger.info("Returning streaming response (async generator) (%.3fs)", duration)
                return StreamingResponse(self._stream_with_error_handling(result), media_type="text/event-stream")

            # If handler returned a Starlette Response directly, pass it through.
            # This lets handlers control status codes (e.g. JSONResponse(data, status_code=404)).
            if isinstance(result, Response):
                status = getattr(result, "status_code", 200)
                # Log at warning level for error responses so operators can distinguish
                # intentional error responses from successful invocations in logs.
                if status >= 400:
                    self.logger.warning("Invocation returned HTTP %d (%.3fs)", status, duration)
                else:
                    self.logger.info("Invocation completed successfully (%.3fs)", duration)
                return result

            self.logger.info("Invocation completed successfully (%.3fs)", duration)
            # Use safe serialization for consistency with streaming paths
            safe_json_string = self._safe_serialize_to_json_string(result)
            return Response(safe_json_string, media_type="application/json")

        except json.JSONDecodeError as e:
            duration = time.time() - start_time
            self.logger.warning("Invalid JSON in request (%.3fs): %s", duration, e)
            return JSONResponse({"error": "Invalid JSON", "details": str(e)}, status_code=400)
        except UnicodeDecodeError as e:
            duration = time.time() - start_time
            self.logger.warning("Invalid encoding in request (%.3fs): %s", duration, e)
            return JSONResponse({"error": "Invalid encoding", "details": str(e)}, status_code=400)
        except HTTPException as e:
            duration = time.time() - start_time
            # Use error level for 5xx to match the generic Exception handler's severity,
            # since server errors warrant the same urgency regardless of how they're raised.
            # Use warning for 4xx since those are intentional client-error responses.
            if e.status_code >= 500:
                self.logger.error("HTTP %d (%.3fs): %s", e.status_code, duration, e.detail)
            else:
                self.logger.warning("HTTP %d (%.3fs): %s", e.status_code, duration, e.detail)
            return JSONResponse({"error": e.detail}, status_code=e.status_code)
        except Exception as e:
            duration = time.time() - start_time
            self.logger.exception("Invocation failed (%.3fs)", duration)
            return JSONResponse({"error": str(e)}, status_code=500)

    def _handle_ping(self, request):
        try:
            status = self.get_current_ping_status()
            self.logger.debug("Ping request - status: %s", status.value)
            return JSONResponse({"status": status.value, "time_of_last_update": int(self._last_status_update_time)})
        except Exception:
            self.logger.exception("Ping endpoint failed")
            return JSONResponse({"status": PingStatus.HEALTHY.value, "time_of_last_update": int(time.time())})

    async def _handle_websocket(self, websocket: WebSocket):
        """Handle WebSocket connections."""
        request_context = self._build_request_context(websocket)

        try:
            handler = self._websocket_handler
            if not handler:
                self.logger.error("No WebSocket handler defined")
                await websocket.close(code=1011)
                return

            self.logger.debug("WebSocket connection established")
            await handler(websocket, request_context)

        except WebSocketDisconnect:
            self.logger.debug("WebSocket disconnected")
        except Exception:
            self.logger.exception("WebSocket handler failed")
            try:
                await websocket.close(code=1011)
            except Exception:
                pass

    def run(self, port: int = 8080, host: Optional[str] = None, **kwargs):
        """Start the Bedrock AgentCore server.

        Args:
            port: Port to serve on, defaults to 8080
            host: Host to bind to, auto-detected if None
            **kwargs: Additional arguments passed to uvicorn.run()
        """
        import os

        import uvicorn

        if host is None:
            if os.path.exists("/.dockerenv") or os.environ.get("DOCKER_CONTAINER"):
                host = "0.0.0.0"  # nosec B104 - Docker needs this to expose the port
            else:
                host = "127.0.0.1"

        # Set default uvicorn parameters, allow kwargs to override
        uvicorn_params = {
            "host": host,
            "port": port,
            "access_log": self.debug,
            "log_level": "info" if self.debug else "warning",
        }
        uvicorn_params.update(kwargs)

        uvicorn.run(self, **uvicorn_params)

    def _ensure_worker_loop(self) -> asyncio.AbstractEventLoop:
        """Lazily create and start a dedicated worker event loop in a background thread.

        The worker loop isolates async handler execution from the main event loop,
        ensuring that blocking async handlers do not prevent /ping from responding.
        """
        if self._worker_loop is not None and self._worker_loop.is_running():
            return self._worker_loop
        with self._worker_loop_lock:
            if self._worker_loop is None or not self._worker_loop.is_running():
                ready = threading.Event()
                self._worker_thread = threading.Thread(
                    target=self._run_worker_loop,
                    args=(ready,),
                    daemon=True,
                    name="agentcore-worker-loop",
                )
                self._worker_thread.start()
                if not ready.wait(timeout=10):
                    raise RuntimeError("agentcore-worker-loop failed to start")
        return self._worker_loop

    def _run_worker_loop(self, ready: threading.Event) -> None:
        """Entry point for the worker loop background thread.

        The event loop is created here (inside the worker thread) rather than in
        the parent thread to avoid conflicts with OpenTelemetry's threading
        instrumentation, which propagates context from the parent thread and can
        cause ``RuntimeError: Cannot run the event loop while another loop is
        running``.
        """
        # Clear any running-loop state that leaked from the parent thread
        # (e.g. via OpenTelemetry's threading instrumentation context propagation).
        # Without this, run_forever() raises RuntimeError because
        # asyncio._get_running_loop() still returns the parent's loop.
        asyncio._set_running_loop(None)
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        self._worker_loop = loop
        loop.call_soon(ready.set)
        loop.run_forever()

    @staticmethod
    async def _run_with_context(coro: Any, ctx: contextvars.Context) -> Any:
        """Run a coroutine after restoring context variables from a snapshot."""
        _restore_context(ctx)
        return await coro

    def _async_gen_to_sync_gen(self, async_gen: Any, ctx: contextvars.Context) -> Any:
        """Bridge an async generator through the worker loop as a sync generator.

        The async generator is iterated on the worker loop. Chunks are sent to
        a thread-safe queue and yielded synchronously. Starlette's StreamingResponse
        iterates this sync generator via iterate_in_threadpool, so the main event
        loop is never blocked.
        """
        worker_loop = self._ensure_worker_loop()
        q: queue.Queue = queue.Queue(maxsize=100)
        _DONE = object()

        async def _produce() -> None:
            _restore_context(ctx)
            try:
                async for chunk in async_gen:
                    q.put((True, chunk))
                q.put((True, _DONE))
            except BaseException as e:
                q.put((False, e))

        worker_loop.call_soon_threadsafe(lambda: worker_loop.create_task(_produce()))

        while True:
            ok, value = q.get()
            if not ok:
                raise value
            if value is _DONE:
                break
            yield value

    async def _invoke_handler(self, handler: Callable, request_context: Any, takes_context: bool, payload: Any) -> Any:
        """Dispatch handler execution based on handler type.

        - Async generator functions: bridged through the worker loop as a sync generator
        - Regular async functions: run on the dedicated worker event loop
        - Sync functions (including sync generators): run in the thread pool

        This ensures the main event loop stays responsive for /ping health checks
        regardless of whether handlers contain blocking operations.
        """
        try:
            args = (payload, request_context) if takes_context else (payload,)
            ctx = contextvars.copy_context()

            if _is_async_gen_callable(handler):
                return self._async_gen_to_sync_gen(handler(*args), ctx)
            elif _is_async_callable(handler):
                worker_loop = self._ensure_worker_loop()
                future = asyncio.run_coroutine_threadsafe(self._run_with_context(handler(*args), ctx), worker_loop)
                result = await asyncio.wrap_future(future)
                if inspect.isasyncgen(result):
                    return self._async_gen_to_sync_gen(result, ctx)
                return result
            else:
                return await run_in_threadpool(ctx.run, handler, *args)
        except Exception:
            handler_name = getattr(handler, "__name__", "unknown")
            self.logger.debug("Handler '%s' execution failed", handler_name)
            raise

    def _handle_task_action(self, payload: dict) -> Optional[JSONResponse]:
        """Handle task management actions if present in payload."""
        action = payload.get("_agent_core_app_action")
        if not action:
            return None

        self.logger.debug("Processing debug action: %s", action)

        try:
            actions = {
                TASK_ACTION_PING_STATUS: lambda: JSONResponse(
                    {
                        "status": self.get_current_ping_status().value,
                        "time_of_last_update": int(self._last_status_update_time),
                    }
                ),
                TASK_ACTION_JOB_STATUS: lambda: JSONResponse(self.get_async_task_info()),
                TASK_ACTION_FORCE_HEALTHY: lambda: (
                    self.force_ping_status(PingStatus.HEALTHY),
                    self.logger.info("Ping status forced to Healthy"),
                    JSONResponse({"forced_status": "Healthy"}),
                )[2],
                TASK_ACTION_FORCE_BUSY: lambda: (
                    self.force_ping_status(PingStatus.HEALTHY_BUSY),
                    self.logger.info("Ping status forced to HealthyBusy"),
                    JSONResponse({"forced_status": "HealthyBusy"}),
                )[2],
                TASK_ACTION_CLEAR_FORCED_STATUS: lambda: (
                    self.clear_forced_ping_status(),
                    self.logger.info("Forced ping status cleared"),
                    JSONResponse({"forced_status": "Cleared"}),
                )[2],
            }

            if action in actions:
                response = actions[action]()
                self.logger.debug("Debug action '%s' completed successfully", action)
                return response

            self.logger.warning("Unknown debug action requested: %s", action)
            return JSONResponse({"error": f"Unknown action: {action}"}, status_code=400)

        except Exception as e:
            self.logger.exception("Debug action '%s' failed", action)
            return JSONResponse({"error": "Debug action failed", "details": str(e)}, status_code=500)

    async def _stream_with_error_handling(self, generator):
        """Wrap async generator to handle errors and convert to SSE format."""
        try:
            async for value in generator:
                yield self._convert_to_sse(value)
        except Exception as e:
            self.logger.exception("Error in async streaming")
            error_event = {
                "error": str(e),
                "error_type": type(e).__name__,
                "message": "An error occurred during streaming",
            }
            yield self._convert_to_sse(error_event)

    def _safe_serialize_to_json_string(self, obj):
        """Safely serialize object directly to JSON string with progressive fallback handling.

        This method eliminates double JSON encoding by returning the JSON string directly,
        avoiding the test-then-encode pattern that leads to redundant json.dumps() calls.
        Used by both streaming and non-streaming responses for consistent behavior.

        Returns:
            str: JSON string representation of the object
        """
        try:
            # First attempt: direct JSON serialization with Unicode support
            return json.dumps(obj, ensure_ascii=False)
        except (TypeError, ValueError, UnicodeEncodeError):
            try:
                # Second attempt: convert to serializable dictionaries, then JSON encode the dictionaries
                converted_obj = convert_complex_objects(obj)
                return json.dumps(converted_obj, ensure_ascii=False)
            except Exception:
                try:
                    # Third attempt: convert to string, then JSON encode the string
                    return json.dumps(str(obj), ensure_ascii=False)
                except Exception as e:
                    # Final fallback: JSON encode error object with ASCII fallback for problematic Unicode
                    self.logger.warning("Failed to serialize object: %s: %s", type(e).__name__, e)
                    error_obj = {"error": "Serialization failed", "original_type": type(obj).__name__}
                    return json.dumps(error_obj, ensure_ascii=False)

    def _convert_to_sse(self, obj) -> bytes:
        """Convert object to Server-Sent Events format using safe serialization.

        Args:
            obj: Object to convert to SSE format

        Returns:
            bytes: SSE-formatted data ready for streaming
        """
        json_string = self._safe_serialize_to_json_string(obj)
        sse_data = f"data: {json_string}\n\n"
        return sse_data.encode("utf-8")

    def _sync_stream_with_error_handling(self, generator):
        """Wrap sync generator to handle errors and convert to SSE format."""
        try:
            for value in generator:
                yield self._convert_to_sse(value)
        except Exception as e:
            self.logger.exception("Error in sync streaming")
            error_event = {
                "error": str(e),
                "error_type": type(e).__name__,
                "message": "An error occurred during streaming",
            }
            yield self._convert_to_sse(error_event)