# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project

from __future__ import annotations

import asyncio
import concurrent.futures
import logging
import queue
import threading
import time
from dataclasses import dataclass
from types import SimpleNamespace
from typing import Any

import janus
import pytest
from vllm.outputs import CompletionOutput, RequestOutput
from vllm.sampling_params import SamplingParams
from vllm.v1.engine import EngineCoreOutput, EngineCoreOutputs, FinishReason
from vllm.v1.engine.exceptions import EngineDeadError
from vllm.v1.metrics.stats import IterationStats

from vllm_omni.engine import OmniEngineCoreOutput
from vllm_omni.engine.errors import NativeKVHandoffError
from vllm_omni.engine.messages import (
    AbortRequestMessage,
    AbortResultMessage,
    AddCompanionRequestMessage,
    CollectiveRPCRequestMessage,
    CollectiveRPCResultMessage,
    ErrorMessage,
    OutputMessage,
    ShutdownRequestMessage,
    StageSubmissionMessage,
)
from vllm_omni.engine.orchestrator import (
    Orchestrator,
    OrchestratorRequestState,
    StreamingSegmentState,
    _build_terminal_empty_output,
)
from vllm_omni.engine.stage_pool import StagePool
from vllm_omni.inputs.data import OmniDiffusionSamplingParams
from vllm_omni.outputs import OmniRequestOutput

pytestmark = [pytest.mark.core_model, pytest.mark.cpu]


class FakeRunningCounter:
    def __init__(self) -> None:
        self.value = 0

    def increment(self) -> None:
        self.value += 1

    def decrement(self) -> None:
        self.value -= 1


@pytest.mark.asyncio
async def test_engine_dead_broadcasts_fatal_to_rpc_waiters(monkeypatch: pytest.MonkeyPatch) -> None:
    rpc_queue: asyncio.Queue = asyncio.Queue()
    orchestrator = Orchestrator(
        request_async_queue=asyncio.Queue(),
        output_async_queue=asyncio.Queue(),
        rpc_async_queue=rpc_queue,
        stage_pools=[],
    )

    async def wait_for_requests() -> None:
        await asyncio.Event().wait()

    async def fail_outputs() -> None:
        raise EngineDeadError("stage engine died")

    monkeypatch.setattr(orchestrator, "_request_handler", wait_for_requests)
    monkeypatch.setattr(orchestrator, "_orchestration_output_handler", fail_outputs)

    await orchestrator.run()

    fatal = rpc_queue.get_nowait()
    assert isinstance(fatal, ErrorMessage)
    assert fatal.fatal is True
    assert "stage engine died" in fatal.error


@dataclass
class OrchestratorFixture:
    orchestrator: Orchestrator
    request_sync_q: Any
    output_sync_q: Any
    queues: tuple[janus.Queue, ...]
    thread: threading.Thread
    result_future: concurrent.futures.Future[None]


@dataclass
class FakePromptRequest:
    request_id: str
    prompt_token_ids: list[int]
    resumable: bool = True


class FakeStageClient:
    def __init__(
        self,
        *,
        stage_type: str = "llm",
        final_output: bool = False,
        final_output_type: str = "text",
        next_inputs: list[dict] | None = None,
        engine_input_source: list[int] | None = None,
        is_comprehension: bool = False,
        model_stage: str | None = None,
        kv_sender_info: dict[str, Any] | None = None,
    ) -> None:
        self.stage_id = 0
        self.replica_id = 0
        self.stage_type = stage_type
        self.final_output = final_output
        self.final_output_type = final_output_type
        self.default_sampling_params = SamplingParams(max_tokens=1)
        self.requires_multimodal_data = False
        self.engine_input_source = list(engine_input_source or [0])
        self.is_comprehension = is_comprehension
        self.model_stage = model_stage
        self.next_inputs = list(next_inputs or [])
        self.custom_process_input_func = None
        self._kv_sender_info = dict(kv_sender_info) if kv_sender_info is not None else None
        self.add_request_calls: list[tuple] = []
        self.abort_calls: list[list[str]] = []
        self.collective_rpc_calls: list[tuple[str, float | None, tuple[Any, ...], dict[str, Any]]] = []
        self.shutdown_calls = 0
        self._engine_core_outputs = queue.Queue()
        self._diffusion_outputs = queue.Queue()

    # Orchestrator-facing interface.
    async def add_request_async(self, *args, **kwargs) -> None:
        self.add_request_calls.append(args)

    async def get_output_async(self):
        try:
            return self._engine_core_outputs.get_nowait()
        except queue.Empty:
            return SimpleNamespace(outputs=[], scheduler_stats=None, finished_requests=None)

    def get_diffusion_output_nowait(self):
        try:
            return self._diffusion_outputs.get_nowait()
        except queue.Empty:
            return None

    def set_engine_outputs(self, outputs) -> None:
        return None

    def process_engine_inputs(self, source_outputs, prompt=None, streaming_context=None):
        return list(self.next_inputs)

    async def abort_requests_async(self, request_ids: list[str]) -> None:
        self.abort_calls.append(list(request_ids))

    async def collective_rpc_async(
        self,
        *,
        method: str,
        timeout: float | None = None,
        args: tuple[Any, ...] = (),
        kwargs: dict[str, Any] | None = None,
    ) -> Any:
        normalized_kwargs = dict(kwargs or {})
        self.collective_rpc_calls.append((method, timeout, args, normalized_kwargs))
        return {
            "supported": False,
            "todo": True,
            "reason": f"{self.__class__.__name__}.collective_rpc_async is not implemented yet",
        }

    def get_kv_sender_info(self) -> dict[str, Any] | None:
        if self._kv_sender_info is None:
            return None
        return dict(self._kv_sender_info)

    def check_health(self) -> None:
        return None

    def shutdown(self) -> None:
        self.shutdown_calls += 1

    # Test helpers for seeding fake stage outputs.
    def push_engine_core_outputs(self, outputs) -> None:
        self._engine_core_outputs.put_nowait(outputs)

    def push_diffusion_output(self, output) -> None:
        self._diffusion_outputs.put_nowait(output)


def test_terminal_empty_audio_output_uses_stage_sample_rate() -> None:
    final_stage = FakeStageClient(final_output=True, final_output_type="audio")
    final_stage.sample_rate = 44100
    final_pool = StagePool(0, [final_stage])

    terminal_output = _build_terminal_empty_output(
        "req-1",
        final_output_type="audio",
        audio_sample_rate=final_pool._infer_audio_sample_rate(),
    )

    assert terminal_output.outputs[0].multimodal_output["sr"] == 44100


class FakeCollectiveRpcStageClient(FakeStageClient):
    def __init__(self, *args, rpc_result: Any = None, **kwargs) -> None:
        super().__init__(*args, **kwargs)
        self.rpc_result = rpc_result

    async def collective_rpc_async(
        self,
        *,
        method: str,
        timeout: float | None = None,
        args: tuple[Any, ...] = (),
        kwargs: dict[str, Any] | None = None,
    ) -> Any:
        normalized_kwargs = dict(kwargs or {})
        self.collective_rpc_calls.append((method, timeout, args, normalized_kwargs))
        return self.rpc_result


class FakeOutputProcessor:
    def __init__(self, *, request_outputs: list[object] | None = None) -> None:
        self.request_outputs = list(request_outputs or [])
        self.add_request_calls: list[tuple[tuple[Any, ...], dict[str, Any]]] = []
        self.abort_calls: list[list[str]] = []

    def add_request(self, *args, **kwargs) -> None:
        self.add_request_calls.append((args, kwargs))
        return None

    def process_outputs(self, *_args, **_kwargs):
        return SimpleNamespace(
            request_outputs=list(self.request_outputs),
            reqs_to_abort=[],
        )

    def abort_requests(self, request_ids, internal: bool = False):
        aborted_ids, _outputs = self.abort_requests_collecting_outputs(request_ids, internal=internal)
        return aborted_ids

    def abort_requests_collecting_outputs(self, request_ids, *, internal: bool = False, commit_state: bool = True):
        """Mirror MultimodalOutputProcessor collecting for AR abort-prefix tests."""
        del internal, commit_state
        ids = list(request_ids)
        self.abort_calls.append(ids)
        outputs: list[RequestOutput] = []
        for rid in ids:
            seeded = next(
                (ro for ro in self.request_outputs if getattr(ro, "request_id", None) == rid),
                None,
            )
            token_ids = list(seeded.outputs[0].token_ids) if seeded is not None and seeded.outputs else [1, 2]
            # Intentionally stamp an internal-looking id on the RequestOutput so
            # StagePool must re-key by the orchestrator id it passed in.
            outputs.append(
                _build_request_output(
                    f"engine-internal-{rid}",
                    token_ids=token_ids,
                    finished=True,
                    finish_reason="abort",
                )
            )
        return ids, outputs

    def update_scheduler_stats(self, _scheduler_stats) -> None:
        return None


class IterationStatsOutputProcessor(FakeOutputProcessor):
    def process_outputs(self, *_args, **kwargs):
        iteration_stats = kwargs.get("iteration_stats")
        if iteration_stats is None and len(_args) >= 3:
            iteration_stats = _args[2]
        assert iteration_stats is not None
        iteration_stats.num_generation_tokens += 3
        return super().process_outputs(*_args, **kwargs)


class RecordingOutputProcessor(FakeOutputProcessor):
    def __init__(self, *, request_outputs: list[object] | None = None) -> None:
        super().__init__(request_outputs=request_outputs)
        self.process_calls: list[tuple[tuple[Any, ...], dict[str, Any]]] = []

    def process_outputs(self, *args, **kwargs):
        self.process_calls.append((args, kwargs))
        return super().process_outputs(*args, **kwargs)


class RecordingStatLogger:
    def __init__(self) -> None:
        self.records: list[tuple[Any, Any, int]] = []

    def record(self, scheduler_stats, iteration_stats, *, engine_idx: int = 0) -> None:
        self.records.append((scheduler_stats, iteration_stats, engine_idx))


def _sampling_params(max_tokens: int = 4) -> SamplingParams:
    return SamplingParams(max_tokens=max_tokens)


def _engine_core_outputs(tag: str, timestamp: float) -> SimpleNamespace:
    return SimpleNamespace(outputs=[tag], timestamp=timestamp, scheduler_stats=None, finished_requests=None)


def _terminal_engine_core_outputs(request_id: str, timestamp: float = 1.0) -> EngineCoreOutputs:
    return EngineCoreOutputs(
        outputs=[
            EngineCoreOutput(
                request_id=request_id,
                new_token_ids=[],
                finish_reason=FinishReason.STOP,
            )
        ],
        timestamp=timestamp,
        finished_requests={request_id},
    )


def _build_request_output(
    request_id: str,
    *,
    token_ids: list[int] | None = None,
    prompt_token_ids: list[int] | None = None,
    finished: bool = True,
    text: str = "test",
    finish_reason: str | None = None,
) -> RequestOutput:
    completion = CompletionOutput(
        index=0,
        text=text,
        token_ids=list(token_ids or [1, 2]),
        cumulative_logprob=0.0,
        logprobs=None,
        finish_reason=(finish_reason if finish_reason is not None else ("stop" if finished else None)),
        stop_reason=None,
    )
    return RequestOutput(
        request_id=request_id,
        prompt="prompt",
        prompt_token_ids=list(prompt_token_ids or [10, 11]),
        prompt_logprobs=None,
        outputs=[completion],
        finished=finished,
        metrics=None,
        lora_request=None,
    )


def _build_stage_pools(
    stage_clients: list[list[FakeStageClient]],
    *,
    output_processors: list[FakeOutputProcessor] | None = None,
    stage_vllm_configs: list[object] | None = None,
) -> list[StagePool]:
    """Build StagePool list from per-stage replica lists.

    ``stage_clients[i]`` is the list of FakeStageClient replicas for stage i.
    """
    num_stages = len(stage_clients)
    if output_processors is None:
        output_processors = [FakeOutputProcessor() for _ in stage_clients]
    if stage_vllm_configs is None:
        stage_vllm_configs = [SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)) for _ in stage_clients]

    pools: list[StagePool] = []
    for stage_id in range(num_stages):
        clients = stage_clients[stage_id]
        if clients[0].stage_type == "diffusion":
            pools.append(StagePool(stage_id, clients[0]))
        else:
            pools.append(
                StagePool(
                    stage_id,
                    clients,
                    output_processor=output_processors[stage_id],
                    stage_vllm_config=stage_vllm_configs[stage_id],
                )
            )
    return pools


def _build_harness(
    stage_clients: list[object],
    *,
    output_processors: list[object] | None = None,
    stage_vllm_configs: list[object] | None = None,
    async_chunk: bool = False,
    log_stats: bool = False,
    stage_pools: list[StagePool] | None = None,
) -> OrchestratorFixture:
    """Build an Orchestrator test harness.

    Accepts either pre-built ``stage_pools`` or flat lists of single-replica
    clients/processors.
    """
    if stage_pools is None:
        # Wrap flat lists into per-stage single-replica lists.
        nested_clients = [[c] for c in stage_clients]
        stage_pools = _build_stage_pools(
            nested_clients,
            output_processors=output_processors,
            stage_vllm_configs=stage_vllm_configs,
        )

    ready_future: concurrent.futures.Future[tuple[Orchestrator, janus.Queue, janus.Queue, janus.Queue]] = (
        concurrent.futures.Future()
    )
    result_future: concurrent.futures.Future[None] = concurrent.futures.Future()

    def _runner() -> None:
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)

        async def _run() -> None:
            request_queue = janus.Queue()
            output_queue = janus.Queue()
            rpc_queue = janus.Queue()
            orchestrator = Orchestrator(
                request_async_queue=request_queue.async_q,
                output_async_queue=output_queue.async_q,
                rpc_async_queue=rpc_queue.async_q,
                stage_pools=stage_pools,
                async_chunk=async_chunk,
                log_stats=log_stats,
            )
            ready_future.set_result((orchestrator, request_queue, output_queue, rpc_queue))
            await orchestrator.run()

        try:
            loop.run_until_complete(_run())
            result_future.set_result(None)
        except Exception as exc:
            result_future.set_exception(exc)
        finally:
            try:
                pending = [task for task in asyncio.all_tasks(loop) if not task.done()]
                for task in pending:
                    task.cancel()
                if pending:
                    loop.run_until_complete(asyncio.gather(*pending, return_exceptions=True))
                loop.run_until_complete(loop.shutdown_asyncgens())
            finally:
                asyncio.set_event_loop(None)
                loop.close()

    thread = threading.Thread(target=_runner, daemon=True, name="test-orchestrator")
    thread.start()

    orchestrator, request_queue, output_queue, rpc_queue = ready_future.result(timeout=5)
    return OrchestratorFixture(
        orchestrator=orchestrator,
        request_sync_q=request_queue.sync_q,
        output_sync_q=output_queue.sync_q,
        queues=(request_queue, output_queue, rpc_queue),
        thread=thread,
        result_future=result_future,
    )


async def _shutdown_orchestrator(orchestrator_fixture: OrchestratorFixture) -> None:
    orchestrator_fixture.request_sync_q.put_nowait(ShutdownRequestMessage())
    await asyncio.to_thread(orchestrator_fixture.thread.join, 5)
    if orchestrator_fixture.thread.is_alive():
        raise AssertionError("Timed out waiting for orchestrator thread shutdown")
    orchestrator_fixture.result_future.result(timeout=0)


async def _wait_for(predicate, *, timeout: float = 2.0) -> None:
    deadline = time.monotonic() + timeout
    while not predicate():
        if time.monotonic() >= deadline:
            raise AssertionError("Timed out waiting for predicate")
        await asyncio.sleep(0.01)


async def _get_output_message(orchestrator_fixture: OrchestratorFixture, *, timeout: float = 2.0) -> OutputMessage:
    deadline = time.monotonic() + timeout
    while True:
        if time.monotonic() >= deadline:
            raise AssertionError("Timed out waiting for orchestrator output")
        try:
            msg = orchestrator_fixture.output_sync_q.get_nowait()
        except queue.Empty:
            await asyncio.sleep(0.01)
            continue
        if isinstance(msg, OutputMessage):
            return msg


async def _get_rpc_message(
    orchestrator_fixture: OrchestratorFixture,
    *,
    timeout: float = 2.0,
) -> CollectiveRPCResultMessage:
    deadline = time.monotonic() + timeout
    rpc_sync_q = orchestrator_fixture.queues[2].sync_q
    while True:
        if time.monotonic() >= deadline:
            raise AssertionError("Timed out waiting for orchestrator rpc output")
        try:
            return rpc_sync_q.get_nowait()
        except queue.Empty:
            await asyncio.sleep(0.01)


async def _enqueue_add_request(
    orchestrator_fixture: OrchestratorFixture,
    *,
    request_id: str,
    prompt,
    original_prompt,
    sampling_params_list,
    final_stage_id: int,
    final_output_stage_ids: list[int] | None = None,
) -> None:
    orchestrator_fixture.request_sync_q.put_nowait(
        StageSubmissionMessage(
            type="add_request",
            request_id=request_id,
            prompt=prompt,
            original_prompt=original_prompt,
            output_prompt_text=None,
            sampling_params_list=sampling_params_list,
            final_stage_id=final_stage_id,
            final_output_stage_ids=final_output_stage_ids,
            preprocess_ms=0.0,
            request_timestamp=time.time(),
            enqueue_ts=time.perf_counter(),
        )
    )


async def _enqueue_abort_request(orchestrator_fixture: OrchestratorFixture, request_ids: list[str]) -> None:
    orchestrator_fixture.request_sync_q.put_nowait(AbortRequestMessage(request_ids=request_ids))


@pytest.fixture
def orchestrator_factory():
    fixtures: list[OrchestratorFixture] = []

    def _factory(*args, **kwargs) -> OrchestratorFixture:
        fixture = _build_harness(*args, **kwargs)
        fixtures.append(fixture)
        return fixture

    yield _factory

    for fixture in fixtures:
        if fixture.thread.is_alive():
            fixture.request_sync_q.put_nowait(ShutdownRequestMessage())
            fixture.thread.join(timeout=5)
        for q in fixture.queues:
            q.close()


# ---------------------------------------------------------------------------
# Existing single-replica tests (adapted to StagePool interface)
# ---------------------------------------------------------------------------


@pytest.mark.asyncio
async def test_run_two_stage_llm(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(
        stage_type="llm",
        final_output=True,
        next_inputs=[{"prompt_token_ids": [7, 8, 9]}],
    )
    processors = [
        FakeOutputProcessor(request_outputs=[_build_request_output("req-llm", token_ids=[3, 4], finished=True)]),
        FakeOutputProcessor(request_outputs=[_build_request_output("req-llm", token_ids=[10, 11], finished=True)]),
    ]
    orchestrator_fixture = orchestrator_factory([stage0, stage1], output_processors=processors)
    request = SimpleNamespace(request_id="req-llm", prompt_token_ids=[1, 2, 3])

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-llm",
            prompt=request,
            original_prompt={"prompt": "hello"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )

        await _wait_for(lambda: len(stage0.add_request_calls) == 1)
        stage0.push_engine_core_outputs(_engine_core_outputs("stage0-raw", 1.0))

        await _wait_for(lambda: len(stage1.add_request_calls) == 1)
        stage1_request = stage1.add_request_calls[0][0]
        assert stage1_request.request_id == "req-llm"
        assert stage1_request.prompt_token_ids == [7, 8, 9]

        stage1.push_engine_core_outputs(_engine_core_outputs("stage1-raw", 2.0))

        output_msg = await _get_output_message(orchestrator_fixture)

        assert output_msg.request_id == "req-llm"
        assert output_msg.stage_id == 1
        assert output_msg.finished is True
        assert output_msg.engine_outputs.request_id == "req-llm"
        assert "req-llm" not in orchestrator_fixture.orchestrator.request_states
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_run_single_stage_diffusion(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="diffusion", final_output=True, final_output_type="image")
    orchestrator_fixture = orchestrator_factory([stage0])
    params = OmniDiffusionSamplingParams()

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-diff",
            prompt={"prompt": "draw a cat"},
            original_prompt={"prompt": "draw a cat"},
            sampling_params_list=[params],
            final_stage_id=0,
        )

        await _wait_for(lambda: len(stage0.add_request_calls) == 1)
        stage0.push_diffusion_output(
            OmniRequestOutput.from_diffusion(
                request_id="req-diff",
                images=[],
                final_output_type="image",
            )
        )

        output_msg = await _get_output_message(orchestrator_fixture)

        assert output_msg.request_id == "req-diff"
        assert output_msg.stage_id == 0
        assert output_msg.finished is True
        assert output_msg.engine_outputs.request_id == "req-diff"
        assert "req-diff" not in orchestrator_fixture.orchestrator.request_states
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_run_single_stage_diffusion_streaming_forwards_intermediate_chunks(orchestrator_factory) -> None:
    """Intermediate diffusion chunks (finished=False) reach the frontend before the final chunk."""
    stage0 = FakeStageClient(stage_type="diffusion", final_output=True, final_output_type="image")
    orchestrator_fixture = orchestrator_factory([stage0])
    params = OmniDiffusionSamplingParams()

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-stream",
            prompt={"prompt": "draw a cat"},
            original_prompt={"prompt": "draw a cat"},
            sampling_params_list=[params],
            final_stage_id=0,
        )

        await _wait_for(lambda: len(stage0.add_request_calls) == 1)
        stage0.push_diffusion_output(
            OmniRequestOutput.from_diffusion(
                request_id="req-stream",
                images=[],
                final_output_type="image",
                custom_output={"chunk": 0},
                finished=False,
            )
        )
        stage0.push_diffusion_output(
            OmniRequestOutput.from_diffusion(
                request_id="req-stream",
                images=[],
                final_output_type="image",
                custom_output={"chunk": 1},
                finished=True,
            )
        )

        output_msgs: list[OutputMessage] = []
        deadline = time.monotonic() + 2.0
        while not output_msgs or not output_msgs[-1].finished:
            if time.monotonic() >= deadline:
                raise AssertionError(
                    f"Timed out waiting for finished orchestrator output, got {len(output_msgs)} message(s)"
                )
            try:
                msg = orchestrator_fixture.output_sync_q.get_nowait()
            except queue.Empty:
                await asyncio.sleep(0.01)
                continue
            if isinstance(msg, OutputMessage):
                output_msgs.append(msg)

        assert [msg.request_id for msg in output_msgs] == ["req-stream", "req-stream"]
        assert [msg.finished for msg in output_msgs] == [False, True]
        assert [msg.engine_outputs.finished for msg in output_msgs] == [False, True]
        assert [msg.engine_outputs.custom_output["chunk"] for msg in output_msgs] == [0, 1]
        await _wait_for(lambda: "req-stream" not in orchestrator_fixture.orchestrator.request_states)
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_run_llm_to_diffusion(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(stage_type="diffusion", final_output=True, final_output_type="image")
    processors = [
        FakeOutputProcessor(request_outputs=[_build_request_output("req-img", token_ids=[3, 4], finished=True)]),
        FakeOutputProcessor(),
    ]
    orchestrator_fixture = orchestrator_factory([stage0, stage1], output_processors=processors)
    request = SimpleNamespace(request_id="req-img", prompt_token_ids=[1, 2, 3])
    params = OmniDiffusionSamplingParams()
    original_prompt = {"prompt": "draw a fox"}

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-img",
            prompt=request,
            original_prompt=original_prompt,
            sampling_params_list=[_sampling_params(), params],
            final_stage_id=1,
        )

        await _wait_for(lambda: len(stage0.add_request_calls) == 1)
        stage0.push_engine_core_outputs(_engine_core_outputs("stage0-raw", 1.0))

        await _wait_for(lambda: len(stage1.add_request_calls) == 1)
        assert stage1.add_request_calls[0] == ("req-img", original_prompt, params)

        stage1.push_diffusion_output(
            OmniRequestOutput.from_diffusion(
                request_id="req-img",
                images=[],
                final_output_type="image",
            )
        )

        output_msg = await _get_output_message(orchestrator_fixture)

        assert output_msg.request_id == "req-img"
        assert output_msg.stage_id == 1
        assert output_msg.finished is True
        assert output_msg.engine_outputs.request_id == "req-img"
        assert "req-img" not in orchestrator_fixture.orchestrator.request_states
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_run_async_chunk(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(stage_type="llm", final_output=True)
    processors = [
        FakeOutputProcessor(request_outputs=[_build_request_output("req-async", token_ids=[1], finished=True)]),
        FakeOutputProcessor(request_outputs=[_build_request_output("req-async", token_ids=[20, 21], finished=True)]),
    ]
    orchestrator_fixture = orchestrator_factory(
        [stage0, stage1],
        output_processors=processors,
        async_chunk=True,
    )
    request = SimpleNamespace(request_id="req-async", prompt_token_ids=[1, 2, 3, 4])

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-async",
            prompt=request,
            original_prompt={"prompt": "hello async"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )

        await _wait_for(lambda: len(stage1.add_request_calls) == 1)
        prewarmed_request = stage1.add_request_calls[0][0]
        assert prewarmed_request.request_id == "req-async"
        assert prewarmed_request.prompt_token_ids
        assert all(token_id == 0 for token_id in prewarmed_request.prompt_token_ids)

        stage1.push_engine_core_outputs(_engine_core_outputs("stage1-final", 3.0))

        await _wait_for(
            lambda: orchestrator_fixture.orchestrator.request_states["req-async"].pending_final_output is not None
        )
        stage0.push_engine_core_outputs(_engine_core_outputs("stage0-final", 3.1))
        output_msg = await _get_output_message(orchestrator_fixture)

        assert output_msg.request_id == "req-async"
        assert output_msg.stage_id == 1
        assert output_msg.finished is True
        assert "req-async" not in orchestrator_fixture.orchestrator.request_states
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_async_chunk_raw_terminal_without_processed_output_finishes_request(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(stage_type="llm", final_output=True, final_output_type="audio")
    orchestrator_fixture = orchestrator_factory(
        [stage0, stage1],
        output_processors=[FakeOutputProcessor(), FakeOutputProcessor()],
        async_chunk=True,
    )
    request = FakePromptRequest(
        request_id="req-stream-terminal",
        prompt_token_ids=[1, 2, 3, 4],
    )

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id=request.request_id,
            prompt=request,
            original_prompt={"prompt": "stream audio"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )

        await _wait_for(lambda: len(stage1.add_request_calls) == 1)
        stage1.push_engine_core_outputs(_terminal_engine_core_outputs(request.request_id))

        output_msg = await _get_output_message(orchestrator_fixture)

        assert output_msg.request_id == request.request_id
        assert output_msg.stage_id == 1
        assert output_msg.finished is True
        assert output_msg.engine_outputs.finished is True
        assert output_msg.engine_outputs.outputs[0].multimodal_output["audio"].numel() == 0
        await _wait_for(lambda: request.request_id not in orchestrator_fixture.orchestrator.request_states)
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_async_chunk_data_then_raw_terminal_finishes_once(orchestrator_factory) -> None:
    request_id = "req-stream-data-terminal"
    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(stage_type="llm", final_output=True, final_output_type="audio")
    final_data = _build_request_output(
        request_id,
        token_ids=[20, 21],
        finished=False,
        text="last audio chunk",
    )
    orchestrator_fixture = orchestrator_factory(
        [stage0, stage1],
        output_processors=[
            FakeOutputProcessor(),
            FakeOutputProcessor(request_outputs=[final_data]),
        ],
        async_chunk=True,
    )
    request = FakePromptRequest(
        request_id=request_id,
        prompt_token_ids=[1, 2, 3, 4],
    )

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id=request_id,
            prompt=request,
            original_prompt={"prompt": "stream audio"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )

        await _wait_for(lambda: len(stage1.add_request_calls) == 1)
        stage1.push_engine_core_outputs(_terminal_engine_core_outputs(request_id))

        data_msg = await _get_output_message(orchestrator_fixture)
        terminal_msg = await _get_output_message(orchestrator_fixture)

        assert data_msg.engine_outputs is final_data
        assert data_msg.finished is False
        assert terminal_msg.request_id == request_id
        assert terminal_msg.stage_id == 1
        assert terminal_msg.finished is True
        assert terminal_msg.engine_outputs.finished is True
        await _wait_for(lambda: request_id not in orchestrator_fixture.orchestrator.request_states)
        await asyncio.sleep(0.05)
        with pytest.raises(queue.Empty):
            orchestrator_fixture.output_sync_q.get_nowait()
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_async_chunk_processed_terminal_and_raw_terminal_finishes_once(orchestrator_factory) -> None:
    request_id = "req-stream-processed-terminal"
    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(stage_type="llm", final_output=True, final_output_type="audio")
    processed_terminal = _build_request_output(
        request_id,
        token_ids=[20, 21],
        finished=True,
        text="last audio chunk",
    )
    orchestrator_fixture = orchestrator_factory(
        [stage0, stage1],
        output_processors=[
            FakeOutputProcessor(),
            FakeOutputProcessor(request_outputs=[processed_terminal]),
        ],
        async_chunk=True,
    )
    request = FakePromptRequest(
        request_id=request_id,
        prompt_token_ids=[1, 2, 3, 4],
    )

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id=request_id,
            prompt=request,
            original_prompt={"prompt": "stream audio"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )

        await _wait_for(lambda: len(stage1.add_request_calls) == 1)
        stage1.push_engine_core_outputs(_terminal_engine_core_outputs(request_id))

        terminal_msg = await _get_output_message(orchestrator_fixture)

        assert terminal_msg.engine_outputs is processed_terminal
        assert terminal_msg.finished is True
        await _wait_for(lambda: request_id not in orchestrator_fixture.orchestrator.request_states)
        await asyncio.sleep(0.05)
        with pytest.raises(queue.Empty):
            orchestrator_fixture.output_sync_q.get_nowait()
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_run_shutdown(orchestrator_factory) -> None:
    stages = [
        FakeStageClient(stage_type="llm", final_output=False),
        FakeStageClient(stage_type="diffusion", final_output=True, final_output_type="image"),
    ]
    orchestrator_fixture = orchestrator_factory(stages)

    await _shutdown_orchestrator(orchestrator_fixture)

    assert not orchestrator_fixture.thread.is_alive()
    for stage in stages:
        assert stage.shutdown_calls == 1


@pytest.mark.asyncio
async def test_run_abort(orchestrator_factory) -> None:
    stages = [
        FakeStageClient(stage_type="llm", final_output=False),
        FakeStageClient(stage_type="llm", final_output=True),
    ]
    processors = [
        FakeOutputProcessor(request_outputs=[_build_request_output("req-abort", token_ids=[1], finished=True)]),
        FakeOutputProcessor(request_outputs=[_build_request_output("req-abort", token_ids=[2], finished=True)]),
    ]
    orchestrator_fixture = orchestrator_factory(stages, output_processors=processors)
    request = SimpleNamespace(request_id="req-abort", prompt_token_ids=[1, 2, 3])

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-abort",
            prompt=request,
            original_prompt={"prompt": "cancel me"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )
        await _wait_for(lambda: len(stages[0].add_request_calls) == 1)

        await _enqueue_abort_request(orchestrator_fixture, ["req-abort"])
        await _wait_for(lambda: bool(stages[0].abort_calls))

        assert stages[0].abort_calls == [["req-abort"]]
        assert stages[1].abort_calls == []
        assert "req-abort" not in orchestrator_fixture.orchestrator.request_states
        # Fire-and-forget abort must not emit an RPC result.
        assert orchestrator_fixture.queues[2].sync_q.empty()
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_run_abort_emits_result_when_rpc_id_set(orchestrator_factory) -> None:
    stages = [
        FakeStageClient(stage_type="llm", final_output=False),
        FakeStageClient(
            stage_type="llm",
            final_output=True,
            next_inputs=[{"prompt_token_ids": [7, 8, 9]}],
        ),
    ]
    processors = [
        FakeOutputProcessor(request_outputs=[_build_request_output("req-ack", token_ids=[1], finished=True)]),
        FakeOutputProcessor(request_outputs=[_build_request_output("req-ack", token_ids=[2], finished=True)]),
    ]
    orchestrator_fixture = orchestrator_factory(stages, output_processors=processors)
    request = SimpleNamespace(request_id="req-ack", prompt_token_ids=[1, 2, 3])

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-ack",
            prompt=request,
            original_prompt={"prompt": "cancel with ack"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )
        await _wait_for(lambda: len(stages[0].add_request_calls) == 1)
        # Abort outputs come from the final AR stage's output processor, and
        # StagePool.abort_requests only collects for requests with a live
        # replica binding. Forward off stage-0 first so stage-1 is bound.
        stages[0].push_engine_core_outputs(_engine_core_outputs("stage0-raw", 1.0))
        await _wait_for(lambda: len(stages[1].add_request_calls) == 1)

        orchestrator_fixture.request_sync_q.put_nowait(AbortRequestMessage(request_ids=["req-ack"], rpc_id="abort-1"))
        result = await _get_rpc_message(orchestrator_fixture)
        assert isinstance(result, AbortResultMessage)
        assert result.rpc_id == "abort-1"
        assert result.success is True
        assert result.error is None
        assert result.rpc_correlation_key == ("abort", "abort-1")
        assert stages[0].abort_calls == [["req-ack"]]
        assert stages[1].abort_calls == [["req-ack"]]
        assert "req-ack" not in orchestrator_fixture.orchestrator.request_states
        assert result.abort_outputs is not None
        assert len(result.abort_outputs) == 1
        abort_msg = result.abort_outputs[0]
        assert abort_msg.request_id == "req-ack"
        assert abort_msg.finished is True
        assert abort_msg.stage_id == 1
        assert list(abort_msg.engine_outputs.outputs[0].token_ids) == [2]
        assert abort_msg.engine_outputs.outputs[0].finish_reason == "abort"
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_abort_marks_only_last_final_stage_output_finished() -> None:
    """A request with two final AR stages must keep earlier abort outputs unfinished."""
    stages = [
        FakeStageClient(stage_type="llm", final_output=True),
        FakeStageClient(stage_type="llm", final_output=True),
    ]
    processors = [
        FakeOutputProcessor(request_outputs=[_build_request_output("req-two", token_ids=[1], finished=True)]),
        FakeOutputProcessor(request_outputs=[_build_request_output("req-two", token_ids=[2], finished=True)]),
    ]
    pools = _build_stage_pools([[stages[0]], [stages[1]]], output_processors=processors)
    pools[0]._request_bindings["req-two"] = 0
    pools[1]._request_bindings["req-two"] = 0

    orchestrator = Orchestrator(
        request_async_queue=asyncio.Queue(),
        output_async_queue=asyncio.Queue(),
        rpc_async_queue=asyncio.Queue(),
        stage_pools=pools,
    )
    orchestrator.request_states["req-two"] = OrchestratorRequestState(
        request_id="req-two",
        final_stage_id=1,
        final_output_stage_ids={0, 1},
    )

    outputs = await orchestrator._abort_request_ids(["req-two"])
    assert [(msg.stage_id, msg.finished) for msg in outputs] == [(0, False), (1, True)]
    assert list(outputs[0].engine_outputs.outputs[0].token_ids) == [1]
    assert list(outputs[1].engine_outputs.outputs[0].token_ids) == [2]


@pytest.mark.asyncio
async def test_handle_abort_emits_error_result_on_failure() -> None:
    rpc_queue: asyncio.Queue = asyncio.Queue()
    orchestrator = Orchestrator(
        request_async_queue=asyncio.Queue(),
        output_async_queue=asyncio.Queue(),
        rpc_async_queue=rpc_queue,
        stage_pools=[],
    )

    async def boom(_request_ids, *, abort=False):
        del _request_ids, abort
        raise RuntimeError("cleanup exploded")

    orchestrator._cleanup_request_ids = boom  # type: ignore[method-assign]

    await orchestrator._handle_abort(AbortRequestMessage(request_ids=["req-fail"], rpc_id="abort-err"))

    result = rpc_queue.get_nowait()
    assert isinstance(result, AbortResultMessage)
    assert result.rpc_id == "abort-err"
    assert result.success is False
    assert "cleanup exploded" in (result.error or "")


# ---------------------------------------------------------------------------
# Multi-replica tests
# ---------------------------------------------------------------------------


@pytest.mark.asyncio
async def test_multi_replica_round_robin_distribution(orchestrator_factory) -> None:
    """Two replicas at stage-0, single replica at stage-1.

    Send two requests — they should land on different stage-0 replicas
    (round-robin), then both forward to the single stage-1 replica.
    """
    stage0_r0 = FakeStageClient(stage_type="llm", final_output=False)
    stage0_r1 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(
        stage_type="llm",
        final_output=True,
        next_inputs=[{"prompt_token_ids": [7, 8]}],
    )

    proc0 = FakeOutputProcessor(request_outputs=[_build_request_output("req-0", token_ids=[3], finished=True)])
    proc1 = FakeOutputProcessor(request_outputs=[_build_request_output("req-0", token_ids=[10], finished=True)])

    default_vllm_cfg = SimpleNamespace(model_config=SimpleNamespace(max_model_len=64))
    stage_pools = _build_stage_pools(
        [[stage0_r0, stage0_r1], [stage1]],
        output_processors=[proc0, proc1],
        stage_vllm_configs=[default_vllm_cfg, default_vllm_cfg],
    )

    orchestrator_fixture = orchestrator_factory([], stage_pools=stage_pools)

    try:
        # Request 0 → should land on replica 0 (RR starts at 0)
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-0",
            prompt=SimpleNamespace(request_id="req-0", prompt_token_ids=[1, 2]),
            original_prompt={"prompt": "hello 0"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )
        await _wait_for(lambda: len(stage0_r0.add_request_calls) == 1)
        assert len(stage0_r1.add_request_calls) == 0

        # Request 1 → should land on replica 1 (RR advances)
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-1",
            prompt=SimpleNamespace(request_id="req-1", prompt_token_ids=[5, 6]),
            original_prompt={"prompt": "hello 1"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )
        await _wait_for(lambda: len(stage0_r1.add_request_calls) == 1)
        assert len(stage0_r0.add_request_calls) == 1  # unchanged

        # Complete req-0 at stage-0 replica-0 → should forward to stage-1
        stage0_r0.push_engine_core_outputs(_engine_core_outputs("s0r0-raw", 1.0))
        await _wait_for(lambda: len(stage1.add_request_calls) == 1)
        assert stage1.add_request_calls[0][0].request_id == "req-0"

        # Complete req-0 at stage-1 → final output
        proc1.request_outputs = [_build_request_output("req-0", token_ids=[10], finished=True)]
        stage1.push_engine_core_outputs(_engine_core_outputs("s1-raw", 2.0))
        output_msg = await _get_output_message(orchestrator_fixture)

        assert output_msg.request_id == "req-0"
        assert output_msg.stage_id == 1
        assert output_msg.finished is True
        assert "req-0" not in orchestrator_fixture.orchestrator.request_states
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_multi_replica_abort_broadcasts_to_all_replicas(orchestrator_factory) -> None:
    """Abort must be sent to every replica across all stages."""
    stage0_r0 = FakeStageClient(stage_type="llm", final_output=False)
    stage0_r1 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(stage_type="llm", final_output=True)

    proc0 = FakeOutputProcessor()
    proc1 = FakeOutputProcessor()

    default_vllm_cfg = SimpleNamespace(model_config=SimpleNamespace(max_model_len=64))
    stage_pools = _build_stage_pools(
        [[stage0_r0, stage0_r1], [stage1]],
        output_processors=[proc0, proc1],
        stage_vllm_configs=[default_vllm_cfg, default_vllm_cfg],
    )
    orchestrator_fixture = orchestrator_factory([], stage_pools=stage_pools)

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-abort-mr",
            prompt=SimpleNamespace(request_id="req-abort-mr", prompt_token_ids=[1]),
            original_prompt={"prompt": "cancel"},
            sampling_params_list=[_sampling_params(), _sampling_params()],
            final_stage_id=1,
        )
        await _wait_for(lambda: len(stage0_r0.add_request_calls) == 1)

        await _enqueue_abort_request(orchestrator_fixture, ["req-abort-mr"])
        await _wait_for(lambda: bool(stage0_r0.abort_calls))

        assert stage0_r0.abort_calls == [["req-abort-mr"]]
        assert stage0_r1.abort_calls == []
        assert stage1.abort_calls == []
        assert "req-abort-mr" not in orchestrator_fixture.orchestrator.request_states
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_multi_replica_shutdown_all_replicas(orchestrator_factory) -> None:
    """Shutdown must shut down every replica across all stages."""
    stage0_r0 = FakeStageClient(stage_type="llm", final_output=False)
    stage0_r1 = FakeStageClient(stage_type="llm", final_output=False)
    stage1 = FakeStageClient(stage_type="llm", final_output=True)

    default_vllm_cfg = SimpleNamespace(model_config=SimpleNamespace(max_model_len=64))
    stage_pools = _build_stage_pools(
        [[stage0_r0, stage0_r1], [stage1]],
        stage_vllm_configs=[default_vllm_cfg, default_vllm_cfg],
    )
    orchestrator_fixture = orchestrator_factory([], stage_pools=stage_pools)

    await _shutdown_orchestrator(orchestrator_fixture)

    assert not orchestrator_fixture.thread.is_alive()
    for client in [stage0_r0, stage0_r1, stage1]:
        assert client.shutdown_calls == 1


@pytest.mark.asyncio
async def test_stage_pool_submit_update_reuses_existing_binding() -> None:
    """A request admitted to one replica must keep using that replica on updates."""
    stage0_r0 = FakeStageClient(stage_type="llm", final_output=False)
    stage0_r1 = FakeStageClient(stage_type="llm", final_output=False)
    pool = StagePool(
        0,
        [stage0_r0, stage0_r1],
        output_processor=FakeOutputProcessor(),
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )

    req0_state = OrchestratorRequestState(
        request_id="req-0",
        sampling_params_list=[_sampling_params()],
        final_stage_id=0,
    )
    req1_state = OrchestratorRequestState(
        request_id="req-1",
        sampling_params_list=[_sampling_params()],
        final_stage_id=0,
    )

    await pool.submit_initial("req-0", req0_state, SimpleNamespace(request_id="req-0", prompt_token_ids=[1, 2]))
    await pool.submit_update("req-0", req0_state, SimpleNamespace(request_id="req-0", prompt_token_ids=[3]))
    await pool.submit_initial("req-1", req1_state, SimpleNamespace(request_id="req-1", prompt_token_ids=[4, 5]))
    await pool.submit_update("req-1", req1_state, SimpleNamespace(request_id="req-1", prompt_token_ids=[6]))

    assert pool.get_bound_replica_id("req-0") == 0
    assert pool.get_bound_replica_id("req-1") == 1
    assert len(stage0_r0.add_request_calls) == 2
    assert len(stage0_r1.add_request_calls) == 2
    assert stage0_r0.add_request_calls[0][0].request_id == "req-0"
    assert stage0_r0.add_request_calls[1][0].request_id == "req-0"
    assert stage0_r1.add_request_calls[0][0].request_id == "req-1"
    assert stage0_r1.add_request_calls[1][0].request_id == "req-1"


@pytest.mark.asyncio
async def test_stage_pool_failed_replica_releases_distributed_affinity_and_stops_polling() -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    pool = StagePool(
        0,
        [stage0],
        output_processor=FakeOutputProcessor(),
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )
    pool._addr_to_replica_id["tcp://replica-0"] = 0
    pool.bind("distributed-request", "tcp://replica-0")
    pool._request_bindings["legacy-request"] = 0

    affected = pool.mark_replica_unavailable(0)

    assert set(affected) == {"distributed-request", "legacy-request"}
    assert pool.get_bound_replica_id("distributed-request") is None
    assert pool.get_bound_replica_id("legacy-request") is None
    assert await pool.poll_llm_raw_output(0) is None


def test_stage_pool_reattached_replica_becomes_available_again() -> None:
    failed_client = FakeStageClient(stage_type="llm", final_output=False)
    replacement_client = FakeStageClient(stage_type="llm", final_output=False)
    pool = StagePool(
        0,
        [failed_client],
        output_processor=FakeOutputProcessor(),
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )
    input_addr = "tcp://replica-0"
    pool._addr_to_replica_id[input_addr] = 0
    pool.mark_replica_unavailable(0)
    removed = pool.remove_client(input_addr)

    replica_id = pool.add_client(input_addr, replacement_client)

    assert removed is failed_client
    assert replica_id == 0
    assert len(pool.clients) == 1
    assert pool.clients[0] is replacement_client
    assert pool.available_replica_ids() == [0]


@pytest.mark.asyncio
async def test_stage_pool_submit_update_refreshes_output_processor_state() -> None:
    output_processor = FakeOutputProcessor()

    class AssertingStageClient(FakeStageClient):
        async def add_request_async(self, *args, **kwargs) -> None:
            if len(self.add_request_calls) == 1:
                prompts = [call_kwargs["prompt"] for _, call_kwargs in output_processor.add_request_calls]
                assert prompts == ["seg-1", "seg-2"]
            await super().add_request_async(*args, **kwargs)

    stage0 = AssertingStageClient(stage_type="llm", final_output=False)
    pool = StagePool(
        0,
        [stage0],
        output_processor=output_processor,
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )
    req_state = OrchestratorRequestState(
        request_id="req-0",
        sampling_params_list=[_sampling_params()],
        final_stage_id=0,
    )

    await pool.submit_initial(
        "req-0",
        req_state,
        SimpleNamespace(request_id="req-0", prompt_token_ids=[1, 2]),
        prompt_text="seg-1",
    )
    await pool.submit_update(
        "req-0",
        req_state,
        SimpleNamespace(request_id="req-0", prompt_token_ids=[3], resumable=True),
        prompt_text="seg-2",
    )

    assert len(output_processor.add_request_calls) == 2
    assert output_processor.add_request_calls[1][1]["prompt"] == "seg-2"


@pytest.mark.asyncio
async def test_handle_streaming_update_unknown_request_is_dropped() -> None:
    """A streaming update for an untracked request must not resurrect it.

    Updates always follow the first-chunk add_request through the same
    ordered submission queue, so an unknown id can only mean the request
    already finished or was aborted (e.g. the client disconnected).
    Falling back to add_request created headless sessions that kept
    cycling through the stages (issue #4271).
    """

    class RecordingPool:
        def __init__(self) -> None:
            self.calls: list[tuple[str, Any]] = []

        async def submit_update(self, request_id, req_state, request, *, prompt_text=None) -> int:
            self.calls.append((request_id, prompt_text))
            return 0

    pool = RecordingPool()
    orchestrator = object.__new__(Orchestrator)
    orchestrator.async_chunk = False
    orchestrator.request_states = {}
    orchestrator.stage_pools = [pool]
    add_request_calls: list[str] = []

    async def record_add_request(msg) -> None:
        add_request_calls.append(msg.request_id)

    orchestrator._handle_add_request = record_add_request

    await orchestrator._handle_streaming_update(
        StageSubmissionMessage(
            type="streaming_update",
            request_id="req-unknown",
            prompt=SimpleNamespace(request_id="req-unknown", prompt_token_ids=[1], resumable=True),
            original_prompt={"prompt": "segment-2"},
            output_prompt_text="segment-2",
            sampling_params_list=[_sampling_params()],
            final_stage_id=0,
            preprocess_ms=0.0,
            request_timestamp=time.time(),
            enqueue_ts=time.perf_counter(),
        )
    )

    assert pool.calls == []
    assert add_request_calls == []
    assert "req-unknown" not in orchestrator.request_states


@pytest.mark.asyncio
@pytest.mark.parametrize("native_kv", [False, True])
async def test_add_request_attaches_native_kv_ticket_before_dispatch(mocker, native_kv) -> None:
    sampling = SamplingParams(extra_args={"keep": "sampling"})
    prompt = SimpleNamespace(sampling_params=SamplingParams(extra_args={"keep": "prompt"}))
    source = StagePool(
        0,
        FakeStageClient(),
        stage_vllm_config=SimpleNamespace(
            kv_transfer_config=SimpleNamespace(kv_role="kv_producer") if native_kv else None
        ),
    )
    target = StagePool(1, FakeStageClient(stage_type="diffusion", final_output=True))
    orchestrator = Orchestrator(
        request_async_queue=asyncio.Queue(),
        output_async_queue=asyncio.Queue(),
        rpc_async_queue=asyncio.Queue(),
        stage_pools=[source, target],
    )

    async def check_dispatch(request_id, req_state, request, **kwargs):
        assert req_state.native_kv_transfer_id == ("xfer-req" if native_kv else None)
        for params, preserved in ((sampling, "sampling"), (request.sampling_params, "prompt")):
            assert params.extra_args["keep"] == preserved
            if native_kv:
                assert params.extra_args["kv_transfer_params"] == {
                    "transfer_id": "xfer-req",
                    "do_remote_decode": True,
                    "do_remote_prefill": False,
                }
            else:
                assert "kv_transfer_params" not in params.extra_args
        return 0

    dispatch = mocker.patch.object(source, "submit_initial", side_effect=check_dispatch)
    await orchestrator._handle_add_request(
        StageSubmissionMessage(
            type="add_request",
            request_id="req",
            prompt=prompt,
            original_prompt={},
            output_prompt_text=None,
            sampling_params_list=[sampling, OmniDiffusionSamplingParams()],
            final_stage_id=1,
            preprocess_ms=0,
            request_timestamp=0,
            enqueue_ts=0,
        )
    )
    dispatch.assert_awaited_once()


def test_native_handoff_uses_bound_replica_and_reports_missing_binding(mocker) -> None:
    orchestrator = object.__new__(Orchestrator)
    orchestrator.stage_pools = [mocker.Mock()]
    orchestrator.stage_pools[0].get_bound_client.return_value = None
    req_state = SimpleNamespace(native_kv_transfer_id="xfer-req")
    output = SimpleNamespace(kv_transfer_params={"num_transfer_tokens": 4})

    with pytest.raises(NativeKVHandoffError, match="bound AR replica"):
        orchestrator._diffusion_submit_kwargs("req", 0, SimpleNamespace(engine_input_source=[0]), req_state, output)
    orchestrator.stage_pools[0].get_bound_client.assert_called_once_with("req")
    # The pool default points at replica 0; this request actually used replica 1.
    orchestrator.stage_pools[0].stage_vllm_config = SimpleNamespace(
        kv_transfer_config=SimpleNamespace(engine_id="ar-0")
    )
    config = SimpleNamespace(engine_id="ar-1", kv_connector_extra_config={"bootstrap_addr": "http://host:8999"})
    orchestrator.stage_pools[0].get_bound_client.return_value = SimpleNamespace(
        vllm_config=SimpleNamespace(kv_transfer_config=config)
    )
    params = orchestrator._diffusion_submit_kwargs(
        "req", 0, SimpleNamespace(engine_input_source=[0]), req_state, output
    )
    assert params["kv_transfer_params"]["remote_engine_id"] == "ar-1"
    assert params["kv_transfer_params"]["remote_bootstrap_addr"] == "http://host:8999"
    assert "remote_engine_id" not in output.kv_transfer_params


@pytest.mark.asyncio
async def test_native_handoff_failure_is_request_scoped(mocker):
    orchestrator = object.__new__(Orchestrator)
    fail = mocker.patch.object(orchestrator, "_fail_request_client_error", new_callable=mocker.AsyncMock)

    def lost_binding():
        raise NativeKVHandoffError("bound AR replica is unavailable")

    assert not await orchestrator._dispatch_or_fail_request(
        lost_binding, req_id="req", stage_id=1, operation="inter-stage forward"
    )
    fail.assert_awaited_once_with(
        "req",
        1,
        "bound AR replica is unavailable",
        status_code=502,
        error_type="NativeKVHandoffError",
        release_owners=True,
    )


async def test_handle_streaming_update_passes_prompt_text_to_stage_pool() -> None:
    class RecordingPool:
        def __init__(self) -> None:
            self.calls: list[tuple[str, Any]] = []

        async def submit_update(self, request_id, req_state, request, *, prompt_text=None) -> int:
            self.calls.append((request_id, prompt_text))
            return 0

    pool = RecordingPool()
    orchestrator = object.__new__(Orchestrator)
    orchestrator.async_chunk = False
    orchestrator.request_states = {
        "req-stream": OrchestratorRequestState(
            request_id="req-stream",
            sampling_params_list=[_sampling_params()],
            final_stage_id=0,
        )
    }
    orchestrator.stage_pools = [pool]

    await orchestrator._handle_streaming_update(
        StageSubmissionMessage(
            type="streaming_update",
            request_id="req-stream",
            prompt=SimpleNamespace(request_id="req-stream", prompt_token_ids=[1], resumable=True),
            original_prompt={"prompt": "segment-2"},
            output_prompt_text="segment-2",
            sampling_params_list=[_sampling_params()],
            final_stage_id=0,
            preprocess_ms=0.0,
            request_timestamp=time.time(),
            enqueue_ts=time.perf_counter(),
        )
    )

    assert pool.calls == [("req-stream", "segment-2")]
    assert orchestrator.request_states["req-stream"].streaming.enabled is True


@pytest.mark.asyncio
async def test_resumable_segment_boundary_builds_stage_metrics() -> None:
    built_metrics = SimpleNamespace(pipeline_timings={})

    class RecordingPool:
        def __init__(self) -> None:
            self.calls: list[list[Any]] = []

        def build_stage_metrics(self, outputs, **_kwargs):
            self.calls.append(outputs)
            return built_metrics

    pool = RecordingPool()
    orchestrator = object.__new__(Orchestrator)
    req_state = OrchestratorRequestState(
        request_id="req-stream",
        sampling_params_list=[_sampling_params()],
        final_stage_id=0,
    )
    req_state.streaming.enabled = True
    req_state.streaming.segments[0] = StreamingSegmentState(finished=True)
    req_state.stage_submit_ts[0] = time.time()
    orchestrator.request_states = {"req-stream": req_state}
    orchestrator.stage_pools = [pool]
    routed: list[Any] = []

    async def record_route(_stage_id, _replica_id, _output, _req_state, stage_metrics):
        routed.append(stage_metrics)

    orchestrator._route_output = record_route
    output = SimpleNamespace(request_id="req-stream", error=None, finished=False)

    await orchestrator._handle_processed_outputs(0, 0, [output])

    assert pool.calls == [[output]]
    assert routed == [built_metrics]


def test_stage_pool_metrics_use_resumable_segment_token_count() -> None:
    class SegmentMetricsOutputProcessor(FakeOutputProcessor):
        def pop_native_text_metrics(self, request_id: str) -> dict[str, Any]:
            assert request_id == "req-stream"
            return {"num_generation_tokens": 3}

    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    pool = StagePool(
        0,
        [stage0],
        output_processor=SegmentMetricsOutputProcessor(),
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )
    output = SimpleNamespace(
        request_id="req-stream",
        outputs=[
            SimpleNamespace(
                cumulative_token_ids=list(range(11)),
                finish_reason=FinishReason.LENGTH,
            )
        ],
    )

    metrics = pool.build_stage_metrics(
        [output],
        submit_ts=time.time(),
        request_timestamp=time.time(),
        replica_id=0,
    )

    assert metrics.num_tokens_out == 3
    assert metrics.output_unit_count == 3
    assert metrics.finish_reason == "length"


def test_image_ttfo_preserves_request_time_and_tracks_stage_time() -> None:
    stage = FakeStageClient(stage_type="diffusion", final_output=True, final_output_type="image")
    pool = StagePool(
        1,
        [stage],
        output_processor=FakeOutputProcessor(),
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )
    output = SimpleNamespace(request_id="req-image", _custom_output={"image": "non-empty"})
    pool.record_output_timestamps([output], output_ts=132.0)

    metrics = pool.build_stage_metrics(
        [output],
        submit_ts=130.0,
        request_timestamp=120.0,
        replica_id=0,
    )

    assert metrics.serving_time_to_first_output_ms == pytest.approx(12000.0)
    assert metrics.image_time_to_first_output_ms == pytest.approx(2000.0)


@pytest.mark.asyncio
async def test_stage_pool_submit_initial_rolls_back_output_processor_when_client_submit_fails() -> None:
    class FailingStageClient(FakeStageClient):
        async def add_request_async(self, *args, **kwargs) -> None:
            raise RuntimeError("submit failed")

    class TrackingOutputProcessor(FakeOutputProcessor):
        def __init__(self) -> None:
            super().__init__()
            self.added_request_ids: list[str] = []
            self.removed_request_ids: list[str] = []

        def add_request(self, request, *_args, **_kwargs) -> None:
            self.added_request_ids.append(request.request_id)

        def remove_request(self, request_id: str) -> None:
            self.removed_request_ids.append(request_id)

    client = FailingStageClient(stage_type="llm", final_output=False)
    output_processor = TrackingOutputProcessor()
    pool = StagePool(
        0,
        [client],
        output_processor=output_processor,
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )
    req_state = OrchestratorRequestState(
        request_id="req-0",
        sampling_params_list=[_sampling_params()],
        final_stage_id=0,
    )

    with pytest.raises(RuntimeError, match="submit failed"):
        await pool.submit_initial("req-0", req_state, SimpleNamespace(request_id="req-0", prompt_token_ids=[1, 2]))

    assert output_processor.added_request_ids == ["req-0"]
    assert output_processor.removed_request_ids == ["req-0"]
    assert pool.get_bound_replica_id("req-0") is None


@pytest.mark.asyncio
async def test_stage_pool_abort_requests_logs_when_binding_is_missing(caplog) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=False)
    pool = StagePool(
        0,
        [stage0],
        output_processor=FakeOutputProcessor(),
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )

    target_logger = logging.getLogger("vllm_omni.engine.stage_pool")
    target_logger.addHandler(caplog.handler)
    prev_level = target_logger.level
    target_logger.setLevel(logging.DEBUG)
    try:
        await pool.abort_requests(["missing-req"])
    finally:
        target_logger.removeHandler(caplog.handler)
        target_logger.setLevel(prev_level)

    assert not stage0.abort_calls
    assert "abort: no live binding for req=missing-req in stage-0" in caplog.text


@pytest.mark.asyncio
async def test_collective_rpc_ignores_invalid_stage_ids(orchestrator_factory, caplog) -> None:
    stage0 = FakeCollectiveRpcStageClient(stage_type="llm", final_output=True, rpc_result={"stage": 0})
    stage1 = FakeCollectiveRpcStageClient(stage_type="llm", final_output=True, rpc_result={"stage": 1})
    stage_pools = _build_stage_pools(
        [[stage0], [stage1]],
        output_processors=[FakeOutputProcessor(), FakeOutputProcessor()],
        stage_vllm_configs=[
            SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
            SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
        ],
    )
    orchestrator_fixture = orchestrator_factory([], stage_pools=stage_pools)

    try:
        target_logger = logging.getLogger("vllm_omni.engine.orchestrator")
        target_logger.addHandler(caplog.handler)
        prev_level = target_logger.level
        target_logger.setLevel(logging.WARNING)
        try:
            orchestrator_fixture.request_sync_q.put_nowait(
                CollectiveRPCRequestMessage(
                    rpc_id="rpc-1",
                    method="list_loras",
                    timeout=None,
                    args=(),
                    kwargs={},
                    stage_ids=[99, 1],
                )
            )

            msg = await _get_rpc_message(orchestrator_fixture)
        finally:
            target_logger.removeHandler(caplog.handler)
            target_logger.setLevel(prev_level)

        assert msg.type == "collective_rpc_result"
        assert msg.rpc_id == "rpc-1"
        assert msg.stage_ids == [1]
        assert msg.results == [{"stage": 1}]
        assert not stage0.collective_rpc_calls
        assert len(stage1.collective_rpc_calls) == 1
        assert "collective_rpc: ignoring invalid stage_id 99" in caplog.text
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_multi_replica_cfg_companion_inherits_parent_affinity(orchestrator_factory) -> None:
    """CFG companions should be routed to the same stage-0 replica as their parent."""
    stage0_r0 = FakeStageClient(stage_type="llm", final_output=False)
    stage0_r1 = FakeStageClient(stage_type="llm", final_output=False)
    default_vllm_cfg = SimpleNamespace(model_config=SimpleNamespace(max_model_len=64))
    stage_pools = _build_stage_pools(
        [[stage0_r0, stage0_r1]],
        output_processors=[FakeOutputProcessor()],
        stage_vllm_configs=[default_vllm_cfg],
    )
    orchestrator_fixture = orchestrator_factory([], stage_pools=stage_pools)

    try:
        # Consume replica-0 first so the parent request binds to replica-1.
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="warmup",
            prompt=SimpleNamespace(request_id="warmup", prompt_token_ids=[0]),
            original_prompt={"prompt": "warmup"},
            sampling_params_list=[_sampling_params()],
            final_stage_id=0,
        )
        await _wait_for(lambda: len(stage0_r0.add_request_calls) == 1)

        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="parent",
            prompt=SimpleNamespace(request_id="parent", prompt_token_ids=[1, 2]),
            original_prompt={"prompt": "parent"},
            sampling_params_list=[_sampling_params()],
            final_stage_id=0,
        )
        await _wait_for(lambda: len(stage0_r1.add_request_calls) == 1)

        orchestrator_fixture.request_sync_q.put_nowait(
            AddCompanionRequestMessage(
                companion_id="parent-neg",
                parent_id="parent",
                role="negative",
                prompt=SimpleNamespace(request_id="parent-neg", prompt_token_ids=[9]),
                companion_prompt_text={"prompt": "negative"},
                sampling_params_list=[_sampling_params()],
            )
        )
        await _wait_for(lambda: len(stage0_r1.add_request_calls) == 2)

        assert stage_pools[0].get_bound_replica_id("parent") == 1
        assert stage_pools[0].get_bound_replica_id("parent-neg") == 1
        assert len(stage0_r0.add_request_calls) == 1
        assert stage0_r1.add_request_calls[0][0].request_id == "parent"
        assert stage0_r1.add_request_calls[1][0].request_id == "parent-neg"
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_orchestrator_records_iteration_stats_without_scheduler_stats(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=True)
    processor = IterationStatsOutputProcessor(
        request_outputs=[_build_request_output("req-stats", token_ids=[1], finished=True)]
    )
    orchestrator_fixture = orchestrator_factory([stage0], output_processors=[processor], log_stats=True)
    stat_logger = RecordingStatLogger()
    orchestrator_fixture.orchestrator._stat_logger = stat_logger
    request = SimpleNamespace(request_id="req-stats", prompt_token_ids=[1, 2])

    try:
        await _enqueue_add_request(
            orchestrator_fixture,
            request_id="req-stats",
            prompt=request,
            original_prompt={"prompt": "hello"},
            sampling_params_list=[_sampling_params()],
            final_stage_id=0,
        )
        await _wait_for(lambda: len(stage0.add_request_calls) == 1)

        stage0.push_engine_core_outputs(_engine_core_outputs("raw-without-scheduler-stats", 1.0))

        await _wait_for(lambda: len(stat_logger.records) == 1)
        scheduler_stats, iteration_stats, engine_idx = stat_logger.records[0]
        assert scheduler_stats is None
        assert iteration_stats is not None
        assert iteration_stats.num_generation_tokens == 3
        assert engine_idx == 0
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_orchestrator_records_scheduler_stats_without_outputs(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=True)
    processor = RecordingOutputProcessor()
    orchestrator_fixture = orchestrator_factory([stage0], output_processors=[processor], log_stats=True)
    stat_logger = RecordingStatLogger()
    orchestrator_fixture.orchestrator._stat_logger = stat_logger
    scheduler_stats = SimpleNamespace(num_running_reqs=0, kv_cache_usage=0.5)

    try:
        stage0.push_engine_core_outputs(
            SimpleNamespace(
                outputs=[],
                timestamp=1.0,
                scheduler_stats=scheduler_stats,
                finished_requests=None,
            )
        )

        await _wait_for(lambda: len(stat_logger.records) == 1)
        recorded_scheduler_stats, iteration_stats, engine_idx = stat_logger.records[0]
        assert recorded_scheduler_stats is scheduler_stats
        assert iteration_stats is None
        assert engine_idx == 0
        assert processor.process_calls[0][0][2] is None
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_orchestrator_does_not_build_iteration_stats_for_finished_only_batch(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=True)
    processor = RecordingOutputProcessor()
    orchestrator_fixture = orchestrator_factory([stage0], output_processors=[processor], log_stats=True)
    stat_logger = RecordingStatLogger()
    orchestrator_fixture.orchestrator._stat_logger = stat_logger

    try:
        stage0.push_engine_core_outputs(
            SimpleNamespace(
                outputs=[],
                timestamp=1.0,
                scheduler_stats=None,
                finished_requests={"req-finished"},
            )
        )

        await _wait_for(lambda: bool(processor.process_calls))
        assert processor.process_calls[0][0][2] is None
        assert stat_logger.records == []
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_orchestrator_does_not_build_iteration_stats_without_stat_logger(orchestrator_factory) -> None:
    stage0 = FakeStageClient(stage_type="llm", final_output=True)
    processor = RecordingOutputProcessor()
    orchestrator_fixture = orchestrator_factory([stage0], output_processors=[processor], log_stats=True)
    orchestrator_fixture.orchestrator._stat_logger = None

    try:
        stage0.push_engine_core_outputs(_engine_core_outputs("raw-output", 1.0))

        await _wait_for(lambda: bool(processor.process_calls))
        assert processor.process_calls[0][0][2] is None
    finally:
        await _shutdown_orchestrator(orchestrator_fixture)


@pytest.mark.asyncio
async def test_stage_pool_preserves_none_iteration_stats() -> None:
    client = FakeStageClient(stage_type="llm", final_output=True)
    processor = RecordingOutputProcessor()
    pool = StagePool(
        0,
        [client],
        output_processor=processor,
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )
    raw_outputs = SimpleNamespace(outputs=["raw"], timestamp=1.0, scheduler_stats=None)

    await pool.process_llm_raw_outputs(0, raw_outputs, iteration_stats=None)

    assert processor.process_calls[0][0][2] is None


@pytest.mark.asyncio
async def test_stage_pool_process_llm_raw_outputs_mutates_iteration_stats() -> None:
    client = FakeStageClient(stage_type="llm", final_output=True)
    processor = IterationStatsOutputProcessor()
    pool = StagePool(
        0,
        [client],
        output_processor=processor,
        stage_vllm_config=SimpleNamespace(model_config=SimpleNamespace(max_model_len=64)),
    )
    raw_outputs = SimpleNamespace(outputs=["raw"], timestamp=1.0, scheduler_stats=None)
    iteration_stats = IterationStats()

    await pool.process_llm_raw_outputs(0, raw_outputs, iteration_stats=iteration_stats)

    assert iteration_stats.num_generation_tokens == 3


@pytest.mark.asyncio
async def test_abort_retry_does_not_repeat_successful_stage_abort():
    class _Pool:
        def __init__(self, *, fail_once: bool = False) -> None:
            self.bound = {"req-a"}
            self.fail_once = fail_once
            self.physical_abort_calls = 0

        async def abort_requests(self, request_ids: list[str]) -> None:
            active = self.bound.intersection(request_ids)
            if not active:
                return
            self.physical_abort_calls += 1
            if self.fail_once:
                self.fail_once = False
                raise RuntimeError("stage abort failed")

        def release_bindings(self, request_ids: list[str]) -> None:
            self.bound.difference_update(request_ids)

    first = _Pool()
    second = _Pool(fail_once=True)
    orchestrator = object.__new__(Orchestrator)
    orchestrator.stage_pools = [first, second]

    with pytest.raises(RuntimeError, match="stage abort failed"):
        await orchestrator._abort_request_ids(["req-a"])

    assert first.bound == set()
    assert first.physical_abort_calls == 1
    assert second.bound == {"req-a"}

    await orchestrator._abort_request_ids(["req-a"])

    assert first.physical_abort_calls == 1
    assert second.physical_abort_calls == 2
    assert second.bound == set()


@pytest.mark.asyncio
async def test_duplex_session_request_error_finish_is_delivered_as_request_error() -> None:
    """A session-owned request the scheduler finished with FinishReason.ERROR
    (e.g. its prompt could not grow past max_model_len) must reach the
    session's consumer as a request-scoped error, not vanish: its terminal
    outputs are not processed like other requests, and the output processor
    may already have dropped the request state."""
    output_queue: asyncio.Queue = asyncio.Queue()
    orchestrator = Orchestrator(
        request_async_queue=asyncio.Queue(),
        output_async_queue=output_queue,
        rpc_async_queue=asyncio.Queue(),
        stage_pools=[],
    )
    duplex_state = OrchestratorRequestState(request_id="duplex-req", session_owned=True)
    plain_state = OrchestratorRequestState(request_id="plain-req")
    reason = "context_length_exceeded: streaming session prompt would grow to 8220 tokens, above max_model_len 8192"

    await orchestrator._report_duplex_session_request_error(
        0,
        0,
        OmniEngineCoreOutput(
            request_id="duplex-req", new_token_ids=[], finish_reason=FinishReason.ERROR, stop_reason=reason
        ),
        duplex_state,
    )
    error = output_queue.get_nowait()
    assert isinstance(error, ErrorMessage)
    assert error.request_id == "duplex-req"
    assert error.stage_id == 0
    assert error.fatal is False
    assert error.error == reason

    # An ordinary segment stop, a segment-finished error and a request that is
    # not session-owned produce nothing.
    await orchestrator._report_duplex_session_request_error(
        0,
        0,
        OmniEngineCoreOutput(request_id="duplex-req", new_token_ids=[], finish_reason=FinishReason.STOP),
        duplex_state,
    )
    await orchestrator._report_duplex_session_request_error(
        0,
        0,
        OmniEngineCoreOutput(
            request_id="duplex-req", new_token_ids=[], finish_reason=FinishReason.ERROR, is_segment_finished=True
        ),
        duplex_state,
    )
    await orchestrator._report_duplex_session_request_error(
        0,
        0,
        OmniEngineCoreOutput(request_id="plain-req", new_token_ids=[], finish_reason=FinishReason.ERROR),
        plain_state,
    )
    assert output_queue.empty()