unsloth/studio/backend/tests/test_active_generations.py

# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0

"""Parallel chats: the active-generation registry and the model-swap gate.

A load/unload has to know which streaming chats it would interrupt. Everything
under test is a dict + threading.Lock, so this passes on every platform.
"""

import os
import sys
import threading

import pytest

_backend = os.path.join(os.path.dirname(__file__), "..")
sys.path.insert(0, _backend)

from state import active_generations


@pytest.fixture(autouse = True)
def _clean_registry():
    active_generations.reset_for_tests()
    yield
    active_generations.reset_for_tests()


# ── registry ──────────────────────────────────────────────────────────


def test_registry_starts_empty():
    assert active_generations.count() == 0
    assert active_generations.snapshot() == []
    assert active_generations.active_thread_ids() == []


def test_entry_lives_only_for_the_block():
    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1", model = "m"):
        assert active_generations.count() == 1
        assert active_generations.active_thread_ids() == ["t1"]
    assert active_generations.count() == 0
    assert active_generations.active_thread_ids() == []


def test_entry_is_removed_even_when_the_block_raises():
    ev = threading.Event()
    with pytest.raises(RuntimeError):
        with active_generations.ActiveGeneration(ev, thread_id = "t1"):
            raise RuntimeError("stream blew up")
    assert active_generations.count() == 0


def test_overlapping_runs_on_one_thread_both_register():
    # A tool continuation registers its next leg before the previous unwinds.
    a, b = threading.Event(), threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "t1"):
        with active_generations.ActiveGeneration(b, thread_id = "t1"):
            assert active_generations.count() == 2
            assert active_generations.active_thread_ids() == ["t1"]
        assert active_generations.count() == 1
    assert active_generations.count() == 0


def test_snapshot_is_json_safe_and_ordered_by_start():
    a, b = threading.Event(), threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "first", model = "m1"):
        with active_generations.ActiveGeneration(b, thread_id = "second", model = "m2"):
            snap = active_generations.snapshot()
    assert [e["thread_id"] for e in snap] == ["first", "second"]
    # The threading.Event must not leak into an HTTP response body.
    assert all("event" not in e for e in snap)
    assert {"handle", "thread_id", "model", "kind", "started_at"} == set(snap[0])


def test_thread_ids_are_deduped_and_skip_unnamed_runs():
    a, b, c = threading.Event(), threading.Event(), threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "t1"):
        with active_generations.ActiveGeneration(b, thread_id = "t1"):
            # A brand-new chat whose first turn races persistence has no id yet.
            with active_generations.ActiveGeneration(c, thread_id = None):
                assert active_generations.active_thread_ids() == ["t1"]
                assert active_generations.count() == 3


# ── cancellation ──────────────────────────────────────────────────────


def test_cancel_all_sets_every_event():
    a, b = threading.Event(), threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "t1"):
        with active_generations.ActiveGeneration(b, thread_id = "t2"):
            assert active_generations.cancel_all() == 2
            assert a.is_set() and b.is_set()


def test_cancel_all_on_an_empty_registry_is_a_no_op():
    assert active_generations.cancel_all() == 0


def test_cancel_thread_leaves_siblings_alone():
    # Per-thread Stop: the rest keep generating, llama-server is untouched.
    a, b = threading.Event(), threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "t1"):
        with active_generations.ActiveGeneration(b, thread_id = "t2"):
            assert active_generations.cancel_thread("t1") == 1
            assert a.is_set()
            assert not b.is_set()


def test_cancel_thread_with_no_match_is_a_no_op():
    a = threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "t1"):
        assert active_generations.cancel_thread("nope") == 0
        assert active_generations.cancel_thread("") == 0
        assert not a.is_set()


def test_cancel_does_not_unregister_entries():
    # __exit__ owns removal, so a generation mid-cleanup is not lost.
    a = threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "t1"):
        active_generations.cancel_all()
        assert active_generations.count() == 1


# ── concurrency ───────────────────────────────────────────────────────


def test_registry_survives_concurrent_register_unregister():
    errors: list[BaseException] = []
    barrier = threading.Barrier(8)

    def worker(i: int) -> None:
        try:
            barrier.wait(timeout = 10)
            for _ in range(50):
                with active_generations.ActiveGeneration(threading.Event(), thread_id = f"t{i}"):
                    active_generations.snapshot()
        except BaseException as exc:  # noqa: BLE001 - surfaced via assert below
            errors.append(exc)

    threads = [threading.Thread(target = worker, args = (i,)) for i in range(8)]
    for t in threads:
        t.start()
    for t in threads:
        t.join(timeout = 30)

    assert errors == []
    assert active_generations.count() == 0


# ── the model-swap gate ───────────────────────────────────────────────


# The gate lives in routes.inference, which pulls the whole inference stack.
def _route_gate():
    pytest.importorskip("fastapi", reason = "inference stack not installed")
    routes_inference = pytest.importorskip(
        "routes.inference", reason = "inference stack not installed"
    )
    return routes_inference._raise_or_cancel_active_generations


@pytest.fixture
def gate():
    return _route_gate()


def test_gate_allows_a_swap_when_nothing_is_generating(gate):
    assert gate(force = False, action = "Loading a model") == 0


def test_gate_refuses_with_409_and_names_the_chats(gate):
    from fastapi import HTTPException

    a, b = threading.Event(), threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "t1"):
        with active_generations.ActiveGeneration(b, thread_id = "t2"):
            with pytest.raises(HTTPException) as exc:
                gate(force = False, action = "Loading a model")
    assert exc.value.status_code == 409
    detail = exc.value.detail
    assert detail["error"] == "active_generations"
    assert detail["running"] == 2
    assert detail["thread_ids"] == ["t1", "t2"]
    # Refusing must not cancel anything.
    assert not a.is_set() and not b.is_set()


def test_gate_message_is_singular_for_one_chat(gate):
    from fastapi import HTTPException

    with active_generations.ActiveGeneration(threading.Event(), thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            gate(force = False, action = "Unloading the model")
    message = exc.value.detail["message"]
    assert "1 chat that is still generating" in message
    assert "Unloading the model" in message


def test_gate_force_cancels_and_returns_the_count(gate):
    a, b = threading.Event(), threading.Event()
    with active_generations.ActiveGeneration(a, thread_id = "t1"):
        with active_generations.ActiveGeneration(b, thread_id = "t2"):
            assert gate(force = True, action = "Loading a model") == 2
            assert a.is_set() and b.is_set()


def test_gate_force_with_nothing_running_is_a_no_op(gate):
    assert gate(force = True, action = "Loading a model") == 0


# ── the route wiring ──────────────────────────────────────────────────


def test_tracked_cancel_registers_the_thread_for_its_block():
    # The single place a generation is recorded, so every streaming path gets it.
    _route_gate()
    from routes.inference import _TrackedCancel

    ev = threading.Event()
    tracker = _TrackedCancel(ev, "cancel-1", thread_id = "t1", model = "m")
    tracker.__enter__()
    try:
        assert active_generations.active_thread_ids() == ["t1"]
        assert active_generations.snapshot()[0]["model"] == "m"
    finally:
        tracker.__exit__(None, None, None)
    assert active_generations.count() == 0


def test_tracked_cancel_shares_its_event_with_the_registry():
    # Reusing the per-run event is what keeps a forced reload off llama-server.
    _route_gate()
    from routes.inference import _TrackedCancel

    ev = threading.Event()
    tracker = _TrackedCancel(ev, "cancel-1", thread_id = "t1")
    tracker.__enter__()
    try:
        active_generations.cancel_all()
        assert ev.is_set()
    finally:
        tracker.__exit__(None, None, None)


def _stub_load_route(monkeypatch, *, active_model_name):
    """Point POST /load at an in-memory safetensors backend.

    active_model_name == the requested path makes the request idempotent, so
    _load_model_impl takes its already_loaded fast return.
    """
    from types import SimpleNamespace

    import routes.inference as inf_mod

    monkeypatch.setattr(inf_mod, "_raise_if_sidecar_swap_in_progress", lambda: None)
    monkeypatch.setattr(inf_mod, "validate_extra_args", lambda args: [])
    monkeypatch.setattr(
        inf_mod,
        "resolve_effective_chat_template_override",
        lambda model_identifier = None, user_override = None: None,
    )
    monkeypatch.setattr(inf_mod, "load_inference_config", lambda name: {})
    monkeypatch.setattr(
        inf_mod,
        "_detect_safetensors_features",
        lambda backend, template, tools = None: {
            "supports_reasoning": False,
            "reasoning_style": "enable_thinking",
            "reasoning_effort_levels": [],
            "reasoning_always_on": False,
            "supports_preserve_thinking": False,
            "supports_tools": False,
        },
    )
    monkeypatch.setattr(inf_mod, "_resolve_loaded_trust_remote_code", lambda *a, **k: False)
    monkeypatch.setattr(
        inf_mod,
        "get_inference_backend",
        lambda: SimpleNamespace(active_model_name = active_model_name, models = {}),
    )
    monkeypatch.setattr(
        inf_mod,
        "get_llama_cpp_backend",
        lambda: SimpleNamespace(is_loaded = False, hf_variant = None, model_identifier = None),
    )
    return inf_mod


def test_idempotent_load_neither_refuses_nor_cancels_running_chats(monkeypatch):
    # Re-applying the resident model hits already_loaded: no llama-server touch, no 409, no stopped chats.
    _route_gate()
    import asyncio

    from models.inference import LoadRequest

    inf_mod = _stub_load_route(monkeypatch, active_model_name = "org/A")

    for force in (False, True):
        ev = threading.Event()
        with active_generations.ActiveGeneration(ev, thread_id = "t1"):
            response = asyncio.run(
                inf_mod.load_model(
                    LoadRequest(model_path = "org/A", force_cancel_active = force),
                    object(),
                    "tester",
                )
            )
        assert response.status == "already_loaded"
        assert not ev.is_set()


def test_a_real_reload_still_refuses_while_chats_stream(monkeypatch):
    # A load that would really replace the model still 409s and names the chats.
    _route_gate()
    import asyncio

    from fastapi import HTTPException

    from models.inference import LoadRequest

    inf_mod = _stub_load_route(monkeypatch, active_model_name = "org/OTHER")

    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            asyncio.run(inf_mod.load_model(LoadRequest(model_path = "org/A"), object(), "tester"))
    assert exc.value.status_code == 409
    assert exc.value.detail["thread_ids"] == ["t1"]
    assert not ev.is_set()


def test_a_forced_load_that_fails_preflight_leaves_the_chats_alone(monkeypatch):
    # Preflight can still reject after the user confirms, so cancelling first ends chats for nothing.
    _route_gate()
    import asyncio
    import contextlib

    from fastapi import HTTPException

    from models.inference import LoadRequest

    inf_mod = _stub_load_route(monkeypatch, active_model_name = "org/OTHER")
    monkeypatch.setattr(inf_mod, "_hf_offline_if_dns_dead", contextlib.nullcontext)
    # Stands in for any preflight refusal; a None here is the route's own 400.
    monkeypatch.setattr(inf_mod.ModelConfig, "from_identifier", staticmethod(lambda **kwargs: None))

    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            asyncio.run(
                inf_mod.load_model(
                    LoadRequest(model_path = "org/A", force_cancel_active = True),
                    object(),
                    "tester",
                )
            )
        # The load was rejected, so the chat must still be streaming.
        assert not ev.is_set()
        assert active_generations.count() == 1
    assert exc.value.status_code == 400


def _stub_standard_load_route(monkeypatch):
    """Drive _load_model_impl down the Unsloth path as far as the pre-teardown drain."""
    import contextlib
    from types import SimpleNamespace

    import routes.inference as inf_mod

    real_sidecar_check = inf_mod._raise_if_sidecar_swap_in_progress
    _stub_load_route(monkeypatch, active_model_name = "org/OTHER")
    # _stub_load_route neutralises the sidecar guard; this test is about it.
    monkeypatch.setattr(inf_mod, "_raise_if_sidecar_swap_in_progress", real_sidecar_check)
    monkeypatch.setattr(inf_mod, "_hf_offline_if_dns_dead", contextlib.nullcontext)
    monkeypatch.setattr(inf_mod, "_mlx_distributed_launch_detected", lambda: False)
    monkeypatch.setattr(
        inf_mod.ModelConfig,
        "from_identifier",
        staticmethod(
            lambda **kwargs: SimpleNamespace(
                is_gguf = False,
                identifier = "org/A",
                display_name = "A",
                is_vision = False,
                gguf_hf_repo = None,
                gguf_variant = None,
            )
        ),
    )
    monkeypatch.setattr(inf_mod, "_effective_load_in_4bit", lambda config, requested: False)
    monkeypatch.setattr(inf_mod, "_resolve_inherited_extra_args", lambda *a, **k: None)
    monkeypatch.setattr(inf_mod, "_guard_chat_load_against_training", lambda *a, **k: None)
    return inf_mod


def test_a_sidecar_swap_reserved_during_the_drain_never_strands_cancelled_chats(monkeypatch):
    # A sidecar install can reserve the swap window during the pre-teardown drain, so the recheck
    # after it is the last rejection point and must precede the cancel, else chats die for nothing.
    _route_gate()
    import asyncio
    import time
    from types import SimpleNamespace

    from fastapi import HTTPException

    from core.inference import llama_keepwarm as kw
    from models.inference import LoadRequest

    import utils.transformers_version as tv

    inf_mod = _stub_standard_load_route(monkeypatch)
    reserved = {"v": False}
    monkeypatch.setattr(tv, "sidecar_swap_in_progress", lambda: reserved["v"])

    # Two tracked requests; the install reserves the window mid-drain when the uncancellable one ends.
    monkeypatch.setattr(kw, "_inflight", 2)

    def _installer():
        time.sleep(0.10)
        kw._inflight = 1  # the non-cancellable request finished ...
        reserved["v"] = True  # ... and an install reserved the swap window
        time.sleep(0.35)
        kw._inflight = 0  # the chat's own request drains last

    thread = threading.Thread(target = _installer, daemon = True)
    ev = threading.Event()
    try:
        with active_generations.ActiveGeneration(ev, thread_id = "t1"):
            thread.start()
            with pytest.raises(HTTPException) as exc:
                asyncio.run(
                    inf_mod.load_model(
                        LoadRequest(model_path = "org/A", force_cancel_active = True),
                        SimpleNamespace(
                            app = SimpleNamespace(state = SimpleNamespace(llama_parallel_slots = 1))
                        ),
                        "tester",
                    )
                )
            # Rejected, so the chat traded for a model it never got must still stream.
            assert not ev.is_set()
            assert active_generations.count() == 1
        assert exc.value.status_code == 409
        assert "transformers installation" in str(exc.value.detail)
    finally:
        thread.join(timeout = 5)
        kw._inflight = 0


def _stub_unload_backends(monkeypatch, *, llama, backend):
    """Point the /unload route at in-memory backends."""
    import routes.inference as inf_mod
    from core.inference import llama_keepwarm as kw

    monkeypatch.setattr(inf_mod, "get_llama_cpp_backend", lambda: llama)
    monkeypatch.setattr(inf_mod, "get_inference_backend", lambda: backend)
    monkeypatch.setattr(inf_mod, "is_registered_native_path_label", lambda *a: False)
    monkeypatch.setattr(kw, "note_model_unloaded", lambda: None)
    return inf_mod, kw


def test_unload_rechecks_active_generations_under_the_lifecycle_gate(monkeypatch):
    # Without the recheck, a chat that starts while this queues on the gate is torn down mid-stream.
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    from fastapi import HTTPException

    from models.inference import UnloadRequest

    torn_down: list[str] = []
    inf_mod, kw = _stub_unload_backends(
        monkeypatch,
        llama = SimpleNamespace(
            is_active = True,
            is_loaded = True,
            model_identifier = "org/A-GGUF",
            unload_model = lambda: torn_down.append("gguf"),
        ),
        backend = SimpleNamespace(
            get_loading_model = lambda: None,
            unload_model = lambda path: torn_down.append("unsloth"),
        ),
    )

    ev = threading.Event()
    started = active_generations.ActiveGeneration(ev, thread_id = "t1")

    async def drive():
        # A load holds the lifecycle gate, so the unload queues behind it.
        kw._lifecycle_lock.acquire()
        task = asyncio.create_task(
            inf_mod.unload_model(UnloadRequest(model_path = "org/A-GGUF"), "tester")
        )
        entered = False
        try:
            await asyncio.sleep(0.1)  # the route is polling the gate
            started.__enter__()  # a chat starts in the meantime
            entered = True
        finally:
            kw._lifecycle_lock.release()
        try:
            return await asyncio.wait_for(task, timeout = 5)
        finally:
            if entered:
                started.__exit__(None, None, None)

    with pytest.raises(HTTPException) as exc:
        asyncio.run(drive())

    # 409, not the catch-all 500 the route wraps unexpected failures in.
    assert exc.value.status_code == 409
    assert exc.value.detail["error"] == "active_generations"
    assert torn_down == []
    assert not ev.is_set()


def _run_unload(
    inf_mod,
    monkeypatch,
    *,
    loaded_gguf,
    requested,
    force,
    torn_down,
    unload_model = None,
):
    """Drive POST /unload against a backend pair with ``loaded_gguf`` resident.

    ``unload_model`` overrides the GGUF teardown so a caller can observe what the
    world looked like at the moment of teardown, not just afterwards.
    """
    import asyncio
    from types import SimpleNamespace

    from models.inference import UnloadRequest

    _stub_unload_backends(
        monkeypatch,
        llama = SimpleNamespace(
            is_active = True,
            is_loaded = True,
            model_identifier = loaded_gguf,
            unload_model = unload_model or (lambda: torn_down.append("gguf")),
        ),
        # Nothing on the standard backend: the GGUF above is what is resident.
        backend = SimpleNamespace(
            get_loading_model = lambda: None,
            active_model_name = None,
            models = {},
            unload_model = lambda path: torn_down.append("unsloth"),
        ),
    )
    return asyncio.run(
        inf_mod.unload_model(
            UnloadRequest(model_path = requested, force_cancel_active = force), "tester"
        )
    )


def test_forced_unload_of_a_stale_model_path_leaves_the_chats_alone(monkeypatch):
    # Eject naming a model another tab swapped out: a no-op success; cancelling first loses runs.
    _route_gate()
    import routes.inference as inf_mod

    torn_down: list[str] = []
    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        response = _run_unload(
            inf_mod,
            monkeypatch,
            loaded_gguf = "org/B-GGUF",  # what the other tab actually loaded
            requested = "org/A-GGUF",  # this tab's stale idea of it
            force = True,
            torn_down = torn_down,
        )
        assert not ev.is_set()
        assert active_generations.count() == 1
    # The resident GGUF was never touched, so nothing was worth cancelling.
    assert "gguf" not in torn_down
    assert response.status == "unloaded"


def test_forced_unload_of_the_loaded_model_still_stops_its_chats(monkeypatch):
    # A real unload must still cancel, or llama-server goes down mid-stream.
    _route_gate()
    import routes.inference as inf_mod

    torn_down: list[str] = []
    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        response = _run_unload(
            inf_mod,
            monkeypatch,
            loaded_gguf = "org/A-GGUF",
            requested = "org/A-GGUF",
            force = True,
            torn_down = torn_down,
        )
        assert ev.is_set()
    assert torn_down == ["gguf"]
    assert response.status == "unloaded"


def test_forced_unload_lets_the_cancelled_chats_unwind_before_teardown(monkeypatch):
    # /unload used to tear down right after the cancel, so a stream told to stop but not yet
    # finished lost its server. Assert the count hits zero BEFORE unload_model runs.
    _route_gate()
    import core.inference.llama_keepwarm as keepwarm
    import routes.inference as inf_mod

    inflight = {"n": 1}
    seen = {}

    def _count(current_request_counted = True, *, include_pending = True):
        # Unwinds one poll after the cancel, like a stream noticing its event.
        if inflight["n"] > 0:
            inflight["n"] -= 1
        return inflight["n"]

    monkeypatch.setattr(keepwarm, "other_inference_request_count", _count)
    monkeypatch.setattr(inf_mod, "_switch_waiter_count", lambda: 0)

    torn_down: list[str] = []
    ev = threading.Event()

    def _record_teardown():
        seen["inflight_at_teardown"] = inflight["n"]
        torn_down.append("gguf")

    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        response = _run_unload(
            inf_mod,
            monkeypatch,
            loaded_gguf = "org/A-GGUF",
            requested = "org/A-GGUF",
            force = True,
            torn_down = torn_down,
            unload_model = _record_teardown,
        )
        assert ev.is_set()

    assert torn_down == ["gguf"]
    assert seen["inflight_at_teardown"] == 0
    assert response.status == "unloaded"


def test_unload_drains_on_the_middleware_count_not_just_the_registry(monkeypatch):
    # A request past the middleware but not yet at its _TrackedCancel is counted but unregistered, so
    # the drain reads the middleware count, not "did we cancel anything": one poll on a quiet server.
    _route_gate()
    import core.inference.llama_keepwarm as keepwarm
    import routes.inference as inf_mod

    polls = {"n": 0}

    def _count(current_request_counted = True, *, include_pending = True):
        polls["n"] += 1
        return 0

    monkeypatch.setattr(keepwarm, "other_inference_request_count", _count)

    torn_down: list[str] = []
    response = _run_unload(
        inf_mod,
        monkeypatch,
        loaded_gguf = "org/A-GGUF",
        requested = "org/A-GGUF",
        force = True,
        torn_down = torn_down,
    )
    assert torn_down == ["gguf"]
    # Polled, but returned on the first read rather than waiting anything out.
    assert polls["n"] == 1
    assert response.status == "unloaded"


def test_unforced_unload_of_a_stale_model_path_is_still_a_no_op(monkeypatch):
    # Same stale Eject unforced: it reaches no teardown, so refusing strands the stale tab's selection.
    _route_gate()
    import routes.inference as inf_mod

    torn_down: list[str] = []
    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        response = _run_unload(
            inf_mod,
            monkeypatch,
            loaded_gguf = "org/B-GGUF",  # what the other tab actually loaded
            requested = "org/A-GGUF",  # this tab's stale idea of it
            force = False,
            torn_down = torn_down,
        )
        assert not ev.is_set()
        assert active_generations.count() == 1
    # The resident GGUF was untouched; only the standard backend's stale-path no-op ran.
    assert torn_down == ["unsloth"]
    assert response.status == "unloaded"


def test_unforced_unload_of_the_loaded_model_still_refuses_while_chats_stream(monkeypatch):
    # The stale skip above must not disarm the gate for a real replacement.
    _route_gate()
    import routes.inference as inf_mod

    from fastapi import HTTPException

    torn_down: list[str] = []
    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            _run_unload(
                inf_mod,
                monkeypatch,
                loaded_gguf = "org/A-GGUF",
                requested = "org/A-GGUF",
                force = False,
                torn_down = torn_down,
            )
    assert exc.value.status_code == 409
    assert exc.value.detail["thread_ids"] == ["t1"]
    assert torn_down == []
    assert not ev.is_set()


def test_unforced_unload_still_refuses_while_a_gguf_load_is_in_flight(monkeypatch):
    # A stale tab's Eject naming the PREVIOUS model while a different one loads. The GGUF branch
    # evicts a live llama-server, so a chat on the previous model must get the 409, not be killed.
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    from fastapi import HTTPException

    from models.inference import UnloadRequest

    torn_down: list[str] = []
    inf_mod, _kw = _stub_unload_backends(
        monkeypatch,
        llama = SimpleNamespace(
            is_active = True,
            is_loaded = False,  # spawned, health check not passed: mid-load
            model_identifier = "org/B-GGUF",
            unload_model = lambda: torn_down.append("gguf"),
        ),
        backend = SimpleNamespace(
            get_loading_model = lambda: None,
            active_model_name = None,
            models = {},
            unload_model = lambda path: torn_down.append("unsloth"),
        ),
    )

    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            asyncio.run(
                inf_mod.unload_model(
                    UnloadRequest(model_path = "org/A-GGUF", force_cancel_active = False),
                    "tester",
                )
            )
    assert exc.value.status_code == 409
    assert torn_down == []
    assert not ev.is_set()


def test_cancelling_an_in_flight_standard_load_is_not_refused_by_the_chat_gate(monkeypatch):
    # The real cancelLoading shape: unforced /unload naming the still-LOADING model. It replaces
    # nothing, so it cannot interrupt a chat and must not 409 (the frontend would drop the error).
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    from models.inference import UnloadRequest

    cancelled: list[str] = []
    torn_down: list[str] = []
    inf_mod, _kw = _stub_unload_backends(
        monkeypatch,
        # Nothing on llama-server: the load in flight is a safetensors one.
        llama = SimpleNamespace(
            is_active = False,
            is_loaded = False,
            model_identifier = None,
            unload_model = lambda: torn_down.append("gguf"),
        ),
        backend = SimpleNamespace(
            get_loading_model = lambda: "org/B",
            cancel_load = lambda path: bool(cancelled.append(path)) or True,
            active_model_name = None,
            models = {},
            unload_model = lambda path: torn_down.append("unsloth"),
        ),
    )

    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        response = asyncio.run(
            inf_mod.unload_model(
                UnloadRequest(model_path = "org/B", force_cancel_active = False), "tester"
            )
        )
        # The chat on the previous model is untouched: the load never reached it.
        assert not ev.is_set()
        assert active_generations.count() == 1
    assert response.status == "unloaded"
    assert cancelled == ["org/B"]
    assert torn_down == []


def test_cancelling_an_in_flight_gguf_load_is_not_refused_by_the_chat_gate(monkeypatch):
    # Same cancelLoading shape on the GGUF fast path: killing that child ends a load, not a chat.
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    from models.inference import UnloadRequest

    torn_down: list[str] = []
    inf_mod, _kw = _stub_unload_backends(
        monkeypatch,
        llama = SimpleNamespace(
            is_active = True,
            is_loaded = False,  # spawned, health check not passed: mid-load
            model_identifier = "org/B-GGUF",
            unload_model = lambda: torn_down.append("gguf"),
        ),
        backend = SimpleNamespace(
            get_loading_model = lambda: None,
            active_model_name = None,
            models = {},
            unload_model = lambda path: torn_down.append("unsloth"),
        ),
    )

    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        response = asyncio.run(
            inf_mod.unload_model(
                UnloadRequest(model_path = "org/B-GGUF", force_cancel_active = False), "tester"
            )
        )
        assert not ev.is_set()
        assert active_generations.count() == 1
    assert response.status == "unloaded"
    assert torn_down == ["gguf"]


def _install_responses_stream_mock(monkeypatch, chunks):
    """Point the direct /v1/responses GGUF pass-through at an in-process
    llama-server. Mirrors the harness in test_responses_tool_passthrough.py."""
    import json
    from types import SimpleNamespace

    import httpx

    import routes.inference as inf_mod

    def handler(request):
        content = "".join(f"data: {json.dumps(chunk)}\n\n" for chunk in chunks)
        content += "data: [DONE]\n\n"
        return httpx.Response(
            200,
            content = content.encode(),
            headers = {"content-type": "text/event-stream"},
        )

    transport = httpx.MockTransport(handler)
    real_async_client = httpx.AsyncClient
    monkeypatch.setattr(
        inf_mod.httpx,
        "AsyncClient",
        lambda *a, **kw: real_async_client(transport = transport, timeout = kw.get("timeout", 600)),
    )
    monkeypatch.setattr(
        inf_mod,
        "get_llama_cpp_backend",
        lambda: SimpleNamespace(
            is_loaded = True,
            is_vision = False,
            context_length = 4096,
            base_url = "http://llama.test",
            supports_reasoning = True,
            reasoning_always_on = False,
            _request_reasoning_kwargs = (
                lambda enable_thinking = None, reasoning_effort = None, preserve_thinking = None: None
            ),
        ),
    )
    return inf_mod


class _NeverDisconnectedRequest:
    async def is_disconnected(self):
        return False


def test_direct_responses_stream_is_visible_to_the_swap_gate(monkeypatch):
    # /v1/responses streams straight to llama-server; unregistered, a non-forced /unload tore it down.
    _route_gate()
    import asyncio

    from models.inference import ChatMessage, ResponsesRequest

    inf_mod = _install_responses_stream_mock(
        monkeypatch, [{"choices": [{"delta": {"content": "33"}}]}]
    )
    payload = ResponsesRequest(input = "hi", stream = True, model = "org/M-GGUF")
    messages = [ChatMessage(role = "user", content = "hi")]
    seen = {}

    async def run():
        response = await inf_mod._responses_stream(payload, messages, _NeverDisconnectedRequest())
        iterator = response.body_iterator
        await iterator.__anext__()
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        async for _ in iterator:
            pass

    asyncio.run(run())

    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M-GGUF"
    # And it unregisters, or one Codex call would 409 every later reload.
    assert active_generations.count() == 0


def test_forced_reload_stops_a_direct_responses_stream(monkeypatch):
    # The registered event must be the one the stream watches, or a forced reload kills a live decode.
    _route_gate()
    import asyncio

    from models.inference import ChatMessage, ResponsesRequest

    inf_mod = _install_responses_stream_mock(
        monkeypatch,
        [
            {"choices": [{"delta": {"content": "3"}}]},
            {"choices": [{"delta": {"content": "3"}}]},
        ],
    )
    payload = ResponsesRequest(input = "hi", stream = True, model = "org/M-GGUF")
    messages = [ChatMessage(role = "user", content = "hi")]

    async def run():
        response = await inf_mod._responses_stream(payload, messages, _NeverDisconnectedRequest())
        iterator = response.body_iterator
        chunks = [await iterator.__anext__()]
        assert active_generations.cancel_all() == 1
        async for chunk in iterator:
            chunks.append(chunk)
        return "".join(c.decode() if isinstance(c, bytes) else c for c in chunks)

    body = asyncio.run(run())

    # Cancelled mid-stream: the run ends without a completed envelope.
    assert "response.completed" not in body
    assert active_generations.count() == 0


def test_forced_reload_stops_a_responses_stream_still_queued_for_a_slot(monkeypatch):
    # The run registers before it holds a decode slot, so cancel_all() must reach it while queued in
    # admission; watching only the client socket lets it open a generation the swap already revoked.
    _route_gate()
    import asyncio

    from core.inference import llama_admission
    from models.inference import ChatMessage, ResponsesRequest

    for name in (
        llama_admission.ADMISSION_CONTROL_ENV,
        llama_admission.ADMISSION_QUEUE_TIMEOUT_ENV,
        llama_admission.ADMISSION_KEEPALIVE_INTERVAL_ENV,
        llama_admission.ADMISSION_MAX_QUEUE_ENV,
    ):
        monkeypatch.delenv(name, raising = False)

    inf_mod = _install_responses_stream_mock(
        monkeypatch, [{"choices": [{"delta": {"content": "33"}}]}]
    )
    payload = ResponsesRequest(input = "hi", stream = True, model = "org/M-GGUF")
    messages = [ChatMessage(role = "user", content = "hi")]

    llama_admission.reset_llama_admission_queues()
    try:

        async def run():
            # Hold the backend's only decode slot so the run below has to queue.
            queue = llama_admission.get_llama_admission_queue("http://llama.test")
            holder = queue.reserve(capacity = 1, config = llama_admission.LlamaAdmissionConfig())
            assert holder.lease_nowait() is not None
            response = await inf_mod._responses_stream(
                payload, messages, _NeverDisconnectedRequest()
            )
            chunks = []

            async def drain():
                async for chunk in response.body_iterator:
                    chunks.append(chunk)

            task = asyncio.create_task(drain())
            for _ in range(500):
                if active_generations.count() == 1:
                    break
                await asyncio.sleep(0.01)
            assert active_generations.count() == 1, "the queued run never registered"
            assert active_generations.cancel_all() == 1
            # Unbounded queue by default: without the tracked event this never returns while the slot is held.
            await asyncio.wait_for(task, timeout = 5)
            return chunks

        chunks = asyncio.run(run())
    finally:
        llama_admission.reset_llama_admission_queues()

    body = "".join(c.decode() if isinstance(c, bytes) else c for c in chunks)
    # It gave up its place instead of taking the slot: no upstream call, no envelope.
    assert "response.created" not in body
    assert active_generations.count() == 0


def _install_completions_stream_mock(monkeypatch, events):
    """Point the /v1/completions proxy at an in-process llama-server."""
    import json
    from types import SimpleNamespace

    import httpx

    import routes.inference as inf_mod

    def handler(request):
        # One network chunk per SSE event: the relay polls its cancel flag between upstream chunks.
        async def _chunks():
            for event in events:
                yield f"data: {json.dumps(event)}\n\n".encode()
            yield b"data: [DONE]\n\n"

        return httpx.Response(
            200,
            content = _chunks(),
            headers = {"content-type": "text/event-stream"},
        )

    transport = httpx.MockTransport(handler)
    real_async_client = httpx.AsyncClient
    monkeypatch.setattr(
        inf_mod.httpx,
        "AsyncClient",
        lambda *a, **kw: real_async_client(transport = transport, timeout = kw.get("timeout", 600)),
    )
    monkeypatch.setattr(
        inf_mod,
        "get_llama_cpp_backend",
        lambda: SimpleNamespace(
            is_loaded = True,
            context_length = 4096,
            base_url = "http://llama.test",
            model_identifier = "org/M-GGUF",
        ),
    )
    monkeypatch.setattr(inf_mod, "_automatic_model_load_may_run", lambda: False)

    async def _no_auto_switch(request, current_subject):
        return await request.json()

    monkeypatch.setattr(inf_mod, "_auto_switch_from_request_body", _no_auto_switch)
    return inf_mod


class _CompletionsRequest(_NeverDisconnectedRequest):
    """Minimal stand-in for the Starlette Request /v1/completions reads."""

    def __init__(self, body):
        from types import SimpleNamespace

        self._body = body
        self.method = "POST"
        self.url = SimpleNamespace(path = "/v1/completions")

    async def json(self):
        return self._body


def test_completions_proxy_stream_is_visible_to_the_swap_gate(monkeypatch):
    # /v1/completions relays from llama-server with no idle drain; unregistered, /unload tore it down.
    _route_gate()
    import asyncio

    inf_mod = _install_completions_stream_mock(monkeypatch, [{"choices": [{"text": "33"}]}])
    request = _CompletionsRequest(
        {"prompt": "hi", "stream": True, "model": "org/M-GGUF", "max_tokens": 8}
    )
    seen = {}

    async def run():
        response = await inf_mod.openai_completions(request, "tester")
        iterator = response.body_iterator
        await iterator.__anext__()
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        async for _ in iterator:
            pass

    asyncio.run(run())

    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M-GGUF"
    # And it unregisters, or one completion would 409 every later reload.
    assert active_generations.count() == 0


def test_forced_reload_stops_a_completions_proxy_stream(monkeypatch):
    # The registered event must be the one the relay watches, or a forced reload kills a live decode.
    _route_gate()
    import asyncio

    inf_mod = _install_completions_stream_mock(
        monkeypatch,
        [{"choices": [{"text": "3"}]}, {"choices": [{"text": "3"}]}],
    )
    request = _CompletionsRequest(
        {"prompt": "hi", "stream": True, "model": "org/M-GGUF", "max_tokens": 8}
    )

    async def run():
        response = await inf_mod.openai_completions(request, "tester")
        iterator = response.body_iterator
        chunks = [await iterator.__anext__()]
        assert active_generations.cancel_all() == 1
        async for chunk in iterator:
            chunks.append(chunk)
        return b"".join(c if isinstance(c, bytes) else c.encode() for c in chunks)

    body = asyncio.run(run())

    # Stopped after the first event instead of relaying the rest.
    assert body.count(b'"text"') == 1
    assert active_generations.count() == 0


def test_completions_proxy_non_stream_is_visible_to_the_swap_gate(monkeypatch):
    # ``stream`` defaults to false, so the non-streaming branch is the common shape and holds
    # llama-server throughout: unregistered, /unload counts zero and force_cancel_active has no event.
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    import httpx

    import routes.inference as inf_mod

    seen = {}

    def handler(request):
        # Sampled mid-flight: exactly the window a concurrent /unload would tear down in.
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        # And the gate must reach this run, not just see it.
        seen["cancelled"] = active_generations.cancel_all()
        return httpx.Response(200, json = {"id": "cmpl-x", "choices": [{"text": "33"}]})

    transport = httpx.MockTransport(handler)
    real_async_client = httpx.AsyncClient
    monkeypatch.setattr(
        inf_mod.httpx,
        "AsyncClient",
        lambda *a, **kw: real_async_client(transport = transport, timeout = kw.get("timeout", 600)),
    )
    # The pooled client too, so a route that took no per-request one still reaches this transport.
    monkeypatch.setattr(
        inf_mod, "nonstreaming_client", lambda: real_async_client(transport = transport)
    )
    monkeypatch.setattr(
        inf_mod,
        "get_llama_cpp_backend",
        lambda: SimpleNamespace(
            is_loaded = True,
            context_length = 4096,
            base_url = "http://llama.test",
            model_identifier = "org/M-GGUF",
        ),
    )
    monkeypatch.setattr(inf_mod, "_automatic_model_load_may_run", lambda: False)

    async def _no_auto_switch(request, current_subject):
        return await request.json()

    monkeypatch.setattr(inf_mod, "_auto_switch_from_request_body", _no_auto_switch)

    request = _CompletionsRequest({"prompt": "hi", "model": "org/M-GGUF", "max_tokens": 8})

    with pytest.raises(asyncio.CancelledError):
        asyncio.run(inf_mod.openai_completions(request, "tester"))

    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M-GGUF"
    assert seen["cancelled"] == 1
    # And it unregisters, or one completion would 409 every later reload.
    assert active_generations.count() == 0


class _EmbeddingsRequest(_NeverDisconnectedRequest):
    """Minimal stand-in for the Starlette Request /v1/embeddings reads."""

    def __init__(self, body):
        from types import SimpleNamespace

        self._body = body
        self.method = "POST"
        self.url = SimpleNamespace(path = "/v1/embeddings")
        self.state = SimpleNamespace(skip_api_monitor = True)

    async def json(self):
        return self._body


def test_embeddings_proxy_is_visible_to_the_swap_gate(monkeypatch):
    # /v1/embeddings holds llama-server for its whole HTTP call: unregistered, a non-forced /unload
    # counts zero and kills the server mid-request (only /load waits on the middleware count).
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    import httpx

    import routes.inference as inf_mod

    seen = {}

    def handler(request):
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        seen["cancelled"] = active_generations.cancel_all()
        return httpx.Response(200, json = {"data": [{"embedding": [0.1, 0.2]}]})

    transport = httpx.MockTransport(handler)
    real_async_client = httpx.AsyncClient
    monkeypatch.setattr(
        inf_mod.httpx,
        "AsyncClient",
        lambda *a, **kw: real_async_client(transport = transport, timeout = kw.get("timeout", 600)),
    )
    monkeypatch.setattr(
        inf_mod, "nonstreaming_client", lambda: real_async_client(transport = transport)
    )
    monkeypatch.setattr(
        inf_mod,
        "get_llama_cpp_backend",
        lambda: SimpleNamespace(
            is_loaded = True,
            context_length = 4096,
            base_url = "http://llama.test",
            model_identifier = "org/M-GGUF",
        ),
    )
    monkeypatch.setattr(inf_mod, "_automatic_model_load_may_run", lambda: False)

    async def _no_auto_switch(request, current_subject):
        return await request.json()

    monkeypatch.setattr(inf_mod, "_auto_switch_from_request_body", _no_auto_switch)

    request = _EmbeddingsRequest({"input": "hi", "model": "org/M-GGUF"})

    with pytest.raises(asyncio.CancelledError):
        asyncio.run(inf_mod.openai_embeddings(request, "tester"))

    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M-GGUF"
    assert seen["cancelled"] == 1
    # And it unregisters, or one embedding would 409 every later reload.
    assert active_generations.count() == 0


def test_active_generations_redacts_native_model_paths(monkeypatch):
    # The legacy stream records active_model_name verbatim (an absolute path locally) and is the only
    # place that serialises it: redact like the error paths so a remote client cannot learn host paths.
    _route_gate()
    import asyncio
    import threading
    from types import SimpleNamespace

    import routes.inference as inf_mod
    from utils.native_path_leases import _remember_native_path_for_redaction

    secret_path = "/home/somebody/models/private-model.gguf"
    _remember_native_path_for_redaction(secret_path, "private-model.gguf")

    request = SimpleNamespace(app = SimpleNamespace(state = SimpleNamespace(llama_parallel_slots = 4)))
    monkeypatch.setattr(inf_mod, "get_llama_cpp_backend", lambda: SimpleNamespace())

    with active_generations.ActiveGeneration(threading.Event(), thread_id = "t1", model = secret_path):
        body = asyncio.run(inf_mod.get_active_generations(request, "tester"))

    assert body["count"] == 1
    assert secret_path not in str(body)
    assert body["active"][0]["model"] == "<native_path>"


def test_legacy_generate_stream_is_visible_to_the_swap_gate(monkeypatch):
    # The legacy /generate/stream decodes on the standard backend throughout: unregistered it passed
    # the advertised 409 gate then blocked on the generation lock, and a forced swap had no event.
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    import routes.inference as inf_mod
    from models.inference import GenerateRequest

    seen = {}

    def _fake_generate_chat_response(**kwargs):
        # Sampled mid-generation: exactly the window an /unload would land in.
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        seen["cancelled"] = active_generations.cancel_all()
        yield "hello"
        yield "world"

    backend = SimpleNamespace(
        active_model_name = "org/M",
        models = {"org/M": {}},
        generate_chat_response = lambda **kw: _fake_generate_chat_response(**kw),
        reset_generation_state = lambda *a: None,
        resize_image = lambda img: img,
    )
    monkeypatch.setattr(inf_mod, "get_inference_backend", lambda: backend)

    async def _drain():
        response = await inf_mod.generate_stream(
            GenerateRequest(messages = [{"role": "user", "content": "hi"}]),
            _NeverDisconnectedRequest(),
            current_subject = "tester",
        )
        async for _ in response.body_iterator:
            pass

    asyncio.run(_drain())

    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M"
    assert seen["cancelled"] == 1
    # And it unregisters, or one legacy stream would 409 every later reload.
    assert active_generations.count() == 0


def _anthropic_stream_args(chunks):
    """(request, cancel_event, run_gen) for the local Anthropic stream helpers."""
    cancel_event = threading.Event()

    def run_gen():
        def _gen():
            for chunk in chunks:
                if cancel_event.is_set():
                    return
                yield chunk

        return _gen()

    return _NeverDisconnectedRequest(), cancel_event, run_gen


def test_local_anthropic_plain_stream_is_visible_to_the_swap_gate(monkeypatch):
    # Only the client-tool pass-through registered, so the no-tool /v1/messages path died mid-response.
    _route_gate()
    import asyncio

    import routes.inference as inf_mod

    request, cancel_event, run_gen = _anthropic_stream_args(["3", "33"])
    seen = {}

    async def run():
        response = await inf_mod._anthropic_plain_stream(
            request, cancel_event, run_gen, "msg_1", "org/M-GGUF"
        )
        iterator = response.body_iterator
        await iterator.__anext__()
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        async for _ in iterator:
            pass

    asyncio.run(run())

    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M-GGUF"
    assert active_generations.count() == 0


def test_forced_reload_stops_a_local_anthropic_plain_stream(monkeypatch):
    # The event registered has to be the one the decode loop watches.
    _route_gate()
    import asyncio

    import routes.inference as inf_mod

    request, cancel_event, run_gen = _anthropic_stream_args(["3", "33", "333"])

    async def run():
        response = await inf_mod._anthropic_plain_stream(
            request, cancel_event, run_gen, "msg_1", "org/M-GGUF"
        )
        iterator = response.body_iterator
        chunks = [await iterator.__anext__()]
        assert active_generations.cancel_all() == 1
        async for chunk in iterator:
            chunks.append(chunk)
        return "".join(c.decode() if isinstance(c, bytes) else c for c in chunks)

    body = asyncio.run(run())

    assert cancel_event.is_set()
    # Cancelled mid-stream: no clean message_stop envelope.
    assert "message_stop" not in body
    assert active_generations.count() == 0


def test_local_anthropic_tool_stream_is_visible_to_the_swap_gate(monkeypatch):
    # Same gap on the server-tool path (enable_tools / Anthropic server tools).
    _route_gate()
    import asyncio

    import routes.inference as inf_mod

    request, cancel_event, run_gen = _anthropic_stream_args(
        [{"type": "content", "text": "3"}, {"type": "content", "text": "33"}]
    )
    seen = {}

    async def run():
        response = await inf_mod._anthropic_tool_stream(
            request, cancel_event, run_gen, "msg_1", "org/M-GGUF"
        )
        iterator = response.body_iterator
        await iterator.__anext__()
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        async for _ in iterator:
            pass

    asyncio.run(run())

    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M-GGUF"
    assert active_generations.count() == 0


def test_load_and_unload_requests_default_to_not_cancelling():
    pytest.importorskip("pydantic", reason = "pydantic not installed")
    from models.inference import LoadRequest, UnloadRequest

    assert LoadRequest(model_path = "m").force_cancel_active is False
    assert UnloadRequest(model_path = "m").force_cancel_active is False
    assert LoadRequest(model_path = "m", force_cancel_active = True).force_cancel_active is True


def _parallel_constants(path: str) -> dict:
    """Read the _PARALLEL_* constants from a file's source.

    Importing run.py would drag in the whole server to read three integers.
    """
    import ast

    with open(path, encoding = "utf-8") as f:
        tree = ast.parse(f.read())
    found = {}
    for node in tree.body:
        if not isinstance(node, ast.Assign):
            continue
        for target in node.targets:
            name = getattr(target, "id", "")
            if name.startswith("_PARALLEL_") and isinstance(node.value, ast.Constant):
                found[name] = node.value.value
    return found


def test_studio_defaults_to_more_than_one_decode_slot():
    # With one slot the admission queue serialises every chat.
    consts = _parallel_constants(os.path.join(_backend, "run.py"))

    assert consts["_PARALLEL_DEFAULT_PLAIN"] > 1
    assert consts["_PARALLEL_MIN"] <= consts["_PARALLEL_DEFAULT_PLAIN"] <= consts["_PARALLEL_MAX"]


def test_cli_and_backend_parallel_defaults_agree():
    # argparse and the typer CLI are separate entry points into the same server.
    backend = _parallel_constants(os.path.join(_backend, "run.py"))
    cli_path = os.path.join(
        os.path.dirname(os.path.dirname(os.path.abspath(_backend))),
        "unsloth_cli",
        "commands",
        "studio.py",
    )
    cli = _parallel_constants(cli_path)

    assert cli["_PARALLEL_DEFAULT_PLAIN"] == backend["_PARALLEL_DEFAULT_PLAIN"]


def _run_server_parallel_default(path: str, consts: dict):
    """Resolve run_server()'s llama_parallel_slots default from run.py's source."""
    import ast

    with open(path, encoding = "utf-8") as f:
        tree = ast.parse(f.read())
    for node in tree.body:
        if not isinstance(node, ast.FunctionDef) or node.name != "run_server":
            continue
        args = node.args.args
        defaults = node.args.defaults
        # defaults align with the tail of the positional arg list.
        for arg, default in zip(args[len(args) - len(defaults) :], defaults):
            if arg.arg != "llama_parallel_slots":
                continue
            if isinstance(default, ast.Constant):
                return default.value
            if isinstance(default, ast.Name):
                return consts.get(default.id)
            return None
    return None


def test_run_server_default_matches_the_cli_parallel_default():
    # colab.py omits llama_parallel_slots, so the signature default is what Colab runs with.
    run_path = os.path.join(_backend, "run.py")
    consts = _parallel_constants(run_path)

    default = _run_server_parallel_default(run_path, consts)

    assert default is not None, "run_server() must keep a llama_parallel_slots default"
    assert default == consts["_PARALLEL_DEFAULT_PLAIN"]
    assert default > 1


def test_colab_launcher_inherits_the_parallel_default():
    # Guard the inheritance itself: an explicit 1 here would resurrect the bug.
    import ast

    colab_path = os.path.join(_backend, "colab.py")
    with open(colab_path, encoding = "utf-8") as f:
        tree = ast.parse(f.read())
    consts = _parallel_constants(os.path.join(_backend, "run.py"))

    calls = [
        node
        for node in ast.walk(tree)
        if isinstance(node, ast.Call) and getattr(node.func, "id", "") == "run_server"
    ]
    assert calls, "colab.py must still launch the backend through run_server()"
    for call in calls:
        for kw in call.keywords:
            if kw.arg != "llama_parallel_slots":
                continue
            value = kw.value.value if isinstance(kw.value, ast.Constant) else None
            assert (
                value is None or value > 1
            ), "colab.py pins llama_parallel_slots to 1; Colab chats would serialise"
    # Whether pinned or inherited, Colab must end up with more than one slot.
    assert consts["_PARALLEL_DEFAULT_PLAIN"] > 1


# ── the point of no return ────────────────────────────────────────────


def test_a_forced_load_that_loses_to_a_sidecar_install_leaves_the_chats_alone(monkeypatch):
    # The destructive cancel is the point of no return: nothing after it may reject the load. A sidecar
    # install can reserve the window during preflight, so its recheck must run before, not after.
    _route_gate()
    import asyncio
    import contextlib
    from types import SimpleNamespace

    from fastapi import HTTPException

    from models.inference import LoadRequest

    inf_mod = _stub_load_route(monkeypatch, active_model_name = "org/OTHER")
    monkeypatch.setattr(inf_mod, "_hf_offline_if_dns_dead", contextlib.nullcontext)
    monkeypatch.setattr(
        inf_mod.ModelConfig,
        "from_identifier",
        staticmethod(
            lambda **kwargs: SimpleNamespace(
                is_gguf = False,
                identifier = "org/A",
                display_name = "A",
                is_vision = False,
                is_lora = False,
                path = None,
            )
        ),
    )
    monkeypatch.setattr(inf_mod, "_mlx_distributed_launch_detected", lambda: False)
    monkeypatch.setattr(inf_mod, "_guard_chat_load_against_training", lambda *a, **k: None)
    monkeypatch.setattr(inf_mod, "_resolve_inherited_extra_args", lambda *a, **k: None)

    # The two route-level checks pass, every check after them 409s.
    seen = {"calls": 0}

    def _sidecar_reserved_during_preflight():
        seen["calls"] += 1
        if seen["calls"] > 2:
            raise HTTPException(
                status_code = 409,
                detail = "A transformers installation is in progress. Retry when it completes.",
            )

    monkeypatch.setattr(
        inf_mod, "_raise_if_sidecar_swap_in_progress", _sidecar_reserved_during_preflight
    )

    fastapi_request = SimpleNamespace(
        app = SimpleNamespace(state = SimpleNamespace(llama_parallel_slots = 1))
    )

    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            asyncio.run(
                inf_mod.load_model(
                    LoadRequest(
                        model_path = "org/A",
                        load_in_4bit = False,
                        force_cancel_active = True,
                    ),
                    fastapi_request,
                    "tester",
                )
            )
        # The load was rejected, so the chat must still be streaming.
        assert not ev.is_set()
        assert active_generations.count() == 1
    assert exc.value.status_code == 409


def test_anthropic_passthrough_registers_nothing_until_its_body_starts():
    # A pass-through response whose body never starts must leave both registries clean: a never-started
    # async generator runs no body code (PEP 342), so an eagerly entered tracker never unregisters.
    _route_gate()
    import asyncio
    import inspect
    from types import SimpleNamespace

    from starlette.requests import ClientDisconnect

    import routes.inference as inf_mod

    llama_backend = SimpleNamespace(
        base_url = "http://127.0.0.1:8080",
        context_length = 4096,
        count_chat_tokens = lambda messages, _unused, tools: 7,
    )

    async def _build():
        return await inf_mod._anthropic_passthrough_stream(
            SimpleNamespace(),
            threading.Event(),
            llama_backend,
            [{"role": "user", "content": "hi"}],
            [],
            0.7,
            0.9,
            40,
            128,
            "msg_1",
            "org/A",
            session_id = "s1",
            cancel_id = "c1",
        )

    # Built and abandoned, as when the request task is cancelled before Starlette calls the response.
    asyncio.run(_build())
    assert active_generations.count() == 0
    assert not inf_mod._CANCEL_REGISTRY

    # The client is gone at header time, so the first send fails and the body generator never runs.
    async def _drive():
        response = await _build()

        async def _receive():
            return {"type": "http.disconnect"}

        async def _send(message):
            raise OSError("client disconnected")

        with pytest.raises(ClientDisconnect):
            await response({"type": "http"}, _receive, _send)

    asyncio.run(_drive())
    assert active_generations.count() == 0
    assert not inf_mod._CANCEL_REGISTRY

    # Still tracked once the body runs: the enter stays inside the generator, under the finally.
    src = inspect.getsource(inf_mod._anthropic_passthrough_stream)
    assert src.index("async def _stream()") < src.index("_tracker.__enter__()")
    assert src.index("_tracker.__enter__()") < src.index("_tracker.__exit__(None, None, None)")


def test_audio_generation_is_visible_to_the_swap_gate(monkeypatch):
    # /audio/generate is non-streaming and holds the model for the whole request: unregistered, a
    # non-forced swap counted zero and could tear it down mid-TTS, and a forced one had no entry.
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    import routes.inference as inf_mod
    from models.inference import ChatCompletionRequest

    seen = {}

    class _TtsBackend:
        active_model_name = "org/TTS"
        models = {"org/TTS": {"is_audio": True}}

        def generate_audio_response(self, **kwargs):
            # Sampled mid-generation: the window a concurrent swap would tear down in.
            seen["count"] = active_generations.count()
            seen["snapshot"] = active_generations.snapshot()
            return (b"RIFFfake", 24000)

    # is_loaded False picks the transformers TTS branch, not the GGUF one.
    monkeypatch.setattr(
        inf_mod,
        "get_llama_cpp_backend",
        lambda: SimpleNamespace(is_loaded = False, _is_audio = False),
    )
    monkeypatch.setattr(inf_mod, "get_inference_backend", lambda: _TtsBackend())

    async def _no_auto_switch(*a, **k):
        return None

    monkeypatch.setattr(inf_mod, "_maybe_auto_switch_model", _no_auto_switch)

    payload = ChatCompletionRequest(
        model = "org/TTS",
        messages = [{"role": "user", "content": "hi"}],
        thread_id = "thread-tts",
    )
    asyncio.run(inf_mod.generate_audio(payload, request = None, current_subject = "tester"))

    assert seen["count"] == 1
    # Named, so the swap dialog can say which chat it would interrupt.
    assert seen["snapshot"][0]["thread_id"] == "thread-tts"
    # And it unregisters, or one TTS call would 409 every later reload.
    assert active_generations.count() == 0


class _ChatRequest(_NeverDisconnectedRequest):
    """Minimal stand-in for the Starlette Request /v1/chat/completions reads."""

    def __init__(self):
        from types import SimpleNamespace

        self.method = "POST"
        self.url = SimpleNamespace(path = "/v1/chat/completions")
        self.state = SimpleNamespace(skip_api_monitor = True)
        self.scope: dict = {}


def _standard_chat_stubs(monkeypatch, backend):
    """Point /v1/chat/completions at a standard (non-GGUF) backend.

    ``supports_tools`` False keeps the request off the safetensors server-tool
    loop, which registers on its own, so the plain default branch is exercised.
    """
    from types import SimpleNamespace

    import routes.inference as inf_mod

    monkeypatch.setattr(
        inf_mod,
        "get_llama_cpp_backend",
        lambda: SimpleNamespace(
            is_loaded = False,
            supports_tools = False,
            is_vision = False,
            context_length = None,
        ),
    )
    monkeypatch.setattr(inf_mod, "get_inference_backend", lambda: backend)
    monkeypatch.setattr(inf_mod, "_automatic_model_load_may_run", lambda: False)
    monkeypatch.setattr(
        inf_mod, "_detect_safetensors_features", lambda *a, **k: {"supports_tools": False}
    )

    async def _no_auto_switch(*a, **k):
        return None

    monkeypatch.setattr(inf_mod, "_maybe_auto_switch_model", _no_auto_switch)
    return inf_mod


def test_standard_non_stream_chat_is_visible_to_the_swap_gate(monkeypatch):
    # ``stream`` defaults to false, so this is the default shape of a standard chat and it holds the
    # worker throughout. Only the streaming branch registered, so a swap truncated the completion.
    _route_gate()
    import asyncio

    import routes.inference as inf_mod
    from models.inference import ChatCompletionRequest

    seen = {}

    class _StandardBackend:
        active_model_name = "org/M"
        models = {"org/M": {"chat_template_info": {"template": "chatml"}}}

        def generate_chat_response(
            self,
            *,
            cancel_event = None,
            stats_holder = None,
            **kwargs,
        ):
            # Sampled mid-generation: exactly the window an /unload lands in.
            seen["count"] = active_generations.count()
            seen["snapshot"] = active_generations.snapshot()
            # And the gate must reach this run, on the event the decode watches.
            seen["cancelled"] = active_generations.cancel_all()
            seen["reached_the_decode"] = cancel_event is not None and cancel_event.is_set()
            yield "33"

        def reset_generation_state(self, caller_cancel_event = None):
            pass

    _standard_chat_stubs(monkeypatch, _StandardBackend())

    payload = ChatCompletionRequest(
        model = "org/M",
        messages = [{"role": "user", "content": "hi"}],
        thread_id = "thread-chat",
    )
    response = asyncio.run(
        inf_mod.openai_chat_completions(payload, _ChatRequest(), current_subject = "tester")
    )

    assert response.status_code == 200
    assert seen["count"] == 1
    # Named, so the swap dialog can say which chat it would interrupt.
    assert seen["snapshot"][0]["thread_id"] == "thread-chat"
    assert seen["cancelled"] == 1
    assert seen["reached_the_decode"]
    # And it unregisters, or one completion would 409 every later reload.
    assert active_generations.count() == 0


def test_standard_non_stream_chat_unregisters_when_it_fails(monkeypatch):
    # A raising backend must not strand an entry: that would 409 every later swap.
    _route_gate()
    import asyncio

    from fastapi import HTTPException

    import routes.inference as inf_mod
    from models.inference import ChatCompletionRequest

    class _BrokenBackend:
        active_model_name = "org/M"
        models = {"org/M": {"chat_template_info": {"template": "chatml"}}}

        def generate_chat_response(self, **kwargs):
            raise RuntimeError("decode exploded")
            yield  # pragma: no cover - generator marker

        def reset_generation_state(self, caller_cancel_event = None):
            pass

    _standard_chat_stubs(monkeypatch, _BrokenBackend())

    payload = ChatCompletionRequest(model = "org/M", messages = [{"role": "user", "content": "hi"}])
    with pytest.raises(HTTPException):
        asyncio.run(
            inf_mod.openai_chat_completions(payload, _ChatRequest(), current_subject = "tester")
        )

    assert active_generations.count() == 0


def test_audio_input_non_stream_chat_is_visible_to_the_swap_gate(monkeypatch):
    # An audio-input model with the default stream=false holds the standard worker throughout. Only
    # the streaming sibling registered, so a non-forced swap could unload it mid-transcription.
    _route_gate()
    import asyncio

    import routes.inference as inf_mod
    from models.inference import ChatCompletionRequest

    seen = {}

    class _AudioInputBackend:
        active_model_name = "org/AUDIO-IN"
        models = {"org/AUDIO-IN": {"has_audio_input": True}}

        def generate_audio_input_response(
            self,
            *,
            cancel_event = None,
            **kwargs,
        ):
            # Sampled mid-transcription: the window a concurrent swap lands in.
            seen["count"] = active_generations.count()
            seen["snapshot"] = active_generations.snapshot()
            seen["cancelled"] = active_generations.cancel_all()
            seen["reached_the_decode"] = cancel_event is not None and cancel_event.is_set()
            yield "33"

        def reset_generation_state(self, caller_cancel_event = None):
            pass

    _standard_chat_stubs(monkeypatch, _AudioInputBackend())
    monkeypatch.setattr(inf_mod, "_decode_audio_base64", lambda _b64: object())

    payload = ChatCompletionRequest(
        model = "org/AUDIO-IN",
        messages = [{"role": "user", "content": "transcribe this"}],
        audio_base64 = "ZmFrZQ==",
        thread_id = "thread-audio-in",
    )
    response = asyncio.run(
        inf_mod.openai_chat_completions(payload, _ChatRequest(), current_subject = "tester")
    )

    assert response.status_code == 200
    assert seen["count"] == 1
    assert seen["snapshot"][0]["thread_id"] == "thread-audio-in"
    assert seen["cancelled"] == 1
    assert seen["reached_the_decode"]
    # And it unregisters, or one transcription would 409 every later reload.
    assert active_generations.count() == 0


def _anthropic_route_stubs(monkeypatch, **overrides):
    """Minimal GGUF backend + request stub for the /v1/messages route."""
    from types import SimpleNamespace

    import routes.inference as inf_mod
    from state.tool_policy import reset_tool_policy

    reset_tool_policy()
    backend = SimpleNamespace(
        is_loaded = True,
        is_vision = False,
        supports_tools = True,
        supports_tool_passthrough = True,
        model_identifier = "org/M-GGUF",
        base_url = "http://llama.test",
        context_length = 4096,
        count_chat_tokens = lambda *a, **k: 2,
    )
    backend.__dict__.update(overrides)
    monkeypatch.setattr(inf_mod, "get_llama_cpp_backend", lambda: backend)
    monkeypatch.setattr(inf_mod, "_automatic_model_load_may_run", lambda: False)
    return inf_mod


class _MessagesRequest(_NeverDisconnectedRequest):
    """Minimal stand-in for the Starlette Request /v1/messages reads."""

    def __init__(self):
        from types import SimpleNamespace

        self.method = "POST"
        self.url = SimpleNamespace(path = "/v1/messages")
        self.state = SimpleNamespace(skip_api_monitor = True)


@pytest.mark.parametrize("with_server_tools", [False, True])
def test_local_anthropic_non_stream_is_visible_to_the_swap_gate(monkeypatch, with_server_tools):
    # ``stream`` defaults to false on /v1/messages, so the non-streaming plain and server-tool branches
    # are the common shape and decode throughout. Only their streaming siblings registered.
    _route_gate()
    import asyncio

    from models.inference import AnthropicMessagesRequest

    seen = {}

    def _sample():
        # Sampled mid-generation: exactly the window an /unload lands in.
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        seen["cancelled"] = active_generations.cancel_all()

    def _gen_plain(*, cancel_event = None, **kwargs):
        _sample()
        seen["reached_the_decode"] = cancel_event is not None and cancel_event.is_set()
        yield "ok"

    def _gen_tools(*, cancel_event = None, **kwargs):
        _sample()
        seen["reached_the_decode"] = cancel_event is not None and cancel_event.is_set()
        yield {"type": "content", "text": "ok"}

    inf_mod = _anthropic_route_stubs(
        monkeypatch,
        generate_chat_completion = _gen_plain,
        generate_chat_completion_with_tools = _gen_tools,
    )

    fields = {"max_tokens": 16, "messages": [{"role": "user", "content": "hi"}]}
    if with_server_tools:
        fields["enable_tools"] = True
        fields["tools"] = [{"type": "web_search_20250305", "name": "web_search"}]
    payload = AnthropicMessagesRequest(**fields)

    response = asyncio.run(
        inf_mod.anthropic_messages(payload, request = _MessagesRequest(), current_subject = "tester")
    )

    assert response.status_code == 200
    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M-GGUF"
    assert seen["cancelled"] == 1
    # The event registered is the one the decode watches, so a forced swap lands.
    assert seen["reached_the_decode"]
    # And it unregisters, or one message would 409 every later reload.
    assert active_generations.count() == 0


def test_anthropic_passthrough_non_stream_is_visible_to_the_swap_gate(monkeypatch):
    # The client-tool pass-through holds llama-server for one non-streaming POST. Its streaming sibling
    # registers inside the body generator; this branch had none, so /unload tore the server down.
    _route_gate()
    import asyncio

    import httpx

    from models.inference import AnthropicMessagesRequest

    seen = {}

    def handler(request):
        seen["count"] = active_generations.count()
        seen["snapshot"] = active_generations.snapshot()
        seen["cancelled"] = active_generations.cancel_all()
        return httpx.Response(
            200,
            json = {
                "choices": [
                    {"message": {"role": "assistant", "content": "33"}, "finish_reason": "stop"}
                ]
            },
        )

    inf_mod = _anthropic_route_stubs(monkeypatch)
    transport = httpx.MockTransport(handler)
    real_async_client = httpx.AsyncClient
    # The pass-through takes a per-request client, so a Stop or forced swap can close it mid-POST.
    monkeypatch.setattr(
        inf_mod,
        "_cancelable_nonstreaming_client",
        lambda: real_async_client(transport = transport),
    )

    # enable_tools False keeps the server-tool loop out, so the client tool takes the pass-through.
    payload = AnthropicMessagesRequest(
        max_tokens = 16,
        messages = [{"role": "user", "content": "hi"}],
        enable_tools = False,
        tools = [{"name": "lookup", "input_schema": {"type": "object", "properties": {}}}],
    )

    response = asyncio.run(
        inf_mod.anthropic_messages(payload, request = _MessagesRequest(), current_subject = "tester")
    )

    assert response.status_code == 200
    assert seen["count"] == 1
    assert seen["snapshot"][0]["model"] == "org/M-GGUF"
    assert seen["cancelled"] == 1
    # And it unregisters, or one message would 409 every later reload.
    assert active_generations.count() == 0


def test_anthropic_passthrough_non_stream_stops_when_the_swap_cancels_it(monkeypatch):
    # Registering is half the job: a pooled client cannot be closed, so the run was cancelled while the
    # POST carried on. The watcher closes a per-request client; the set event makes that error a cancel.
    _route_gate()
    import asyncio

    import httpx

    from models.inference import AnthropicMessagesRequest

    seen = {}

    def handler(request):
        # Stand in for a forced swap mid-decode: cancel, then fail the transport as closing would.
        seen["cancelled"] = active_generations.cancel_all()
        raise httpx.ConnectError("client closed")

    inf_mod = _anthropic_route_stubs(monkeypatch)
    transport = httpx.MockTransport(handler)
    real_async_client = httpx.AsyncClient
    monkeypatch.setattr(
        inf_mod,
        "_cancelable_nonstreaming_client",
        lambda: real_async_client(transport = transport),
    )

    payload = AnthropicMessagesRequest(
        max_tokens = 16,
        messages = [{"role": "user", "content": "hi"}],
        enable_tools = False,
        tools = [{"name": "lookup", "input_schema": {"type": "object", "properties": {}}}],
    )

    with pytest.raises(asyncio.CancelledError):
        asyncio.run(
            inf_mod.anthropic_messages(
                payload, request = _MessagesRequest(), current_subject = "tester"
            )
        )

    assert seen["cancelled"] == 1
    # Cancelled or not, the entry must go, or one message 409s every later reload.
    assert active_generations.count() == 0


def test_audio_generation_unregisters_when_it_fails(monkeypatch):
    # A raising backend must not strand an entry: that would 409 every later load.
    _route_gate()
    import asyncio
    from types import SimpleNamespace

    from fastapi import HTTPException

    import routes.inference as inf_mod
    from models.inference import ChatCompletionRequest

    class _BrokenTtsBackend:
        active_model_name = "org/TTS"
        models = {"org/TTS": {"is_audio": True}}

        def generate_audio_response(self, **kwargs):
            raise RuntimeError("codec exploded")

    monkeypatch.setattr(
        inf_mod,
        "get_llama_cpp_backend",
        lambda: SimpleNamespace(is_loaded = False, _is_audio = False),
    )
    monkeypatch.setattr(inf_mod, "get_inference_backend", lambda: _BrokenTtsBackend())

    async def _no_auto_switch(*a, **k):
        return None

    monkeypatch.setattr(inf_mod, "_maybe_auto_switch_model", _no_auto_switch)

    payload = ChatCompletionRequest(
        model = "org/TTS",
        messages = [{"role": "user", "content": "hi"}],
    )
    with pytest.raises(HTTPException):
        asyncio.run(inf_mod.generate_audio(payload, request = None, current_subject = "tester"))

    assert active_generations.count() == 0


# ── sidecar install: carrying a confirmed swap through ─────────────────


def _stub_install_route(monkeypatch, *, in_flight_events):
    """Point POST /install-latest-transformers at an in-memory sidecar install.

    ``in_flight_events`` stands in for the middleware's in-flight count: a
    request is counted until its stream observes the cancel event and unwinds,
    which is the coupling the installer's guard actually reads.
    """
    from types import SimpleNamespace

    import core.inference.llama_keepwarm as keepwarm
    import routes.inference as inf_mod
    import utils.transformers_latest as latest_mod
    import utils.transformers_version as version_mod

    calls = {"installed": [], "released": 0}

    monkeypatch.setattr(version_mod, "try_begin_sidecar_swap", lambda: True)

    def _end_sidecar_swap():
        calls["released"] += 1

    monkeypatch.setattr(version_mod, "end_sidecar_swap", _end_sidecar_swap)

    import core.export as export_mod
    import core.training as training_mod

    monkeypatch.setattr(
        training_mod,
        "get_training_backend",
        lambda: SimpleNamespace(is_training_active = lambda: False),
    )
    monkeypatch.setattr(
        export_mod,
        "get_export_backend",
        lambda: SimpleNamespace(is_export_active = lambda: False, current_checkpoint = None),
    )
    monkeypatch.setattr(
        inf_mod,
        "get_inference_backend",
        lambda: SimpleNamespace(active_model_name = None, load_generation = 0),
    )

    def _fake_in_flight(current_request_counted = True, *, include_pending = True):
        return sum(1 for ev in in_flight_events if not ev.is_set())

    monkeypatch.setattr(keepwarm, "other_inference_request_count", _fake_in_flight)

    def _install(version, before_swap, *args, **kwargs):
        calls["installed"].append(version)
        return {"success": True, "version": version, "message": "installed"}

    monkeypatch.setattr(latest_mod, "install_latest_transformers", _install)
    return inf_mod, calls


def test_confirmed_install_stops_the_chats_it_was_given_permission_to_stop(monkeypatch):
    # The install sits between the swap's "stop N chats" prompt and the /load carrying the
    # confirmation, and refuses while those chats run, so a confirmed install cancels them itself.
    _route_gate()
    import asyncio

    from models.inference import InstallLatestTransformersRequest

    ev = threading.Event()
    inf_mod, calls = _stub_install_route(monkeypatch, in_flight_events = [ev])

    with active_generations.ActiveGeneration(ev, thread_id = "t1", model = "org/M-GGUF"):
        response = asyncio.run(
            inf_mod.install_latest_transformers_route(
                InstallLatestTransformersRequest(version = "5.0.0", force_cancel_active = True),
                "tester",
            )
        )
        assert ev.is_set()

    assert response.success is True
    assert calls["installed"] == ["5.0.0"]


def test_unconfirmed_install_still_refuses_while_chats_stream(monkeypatch):
    # Unchanged for every caller that never confirmed (second tab, desktop, curl): no flag, no cancel.
    _route_gate()
    import asyncio

    from fastapi import HTTPException

    from models.inference import InstallLatestTransformersRequest

    ev = threading.Event()
    inf_mod, calls = _stub_install_route(monkeypatch, in_flight_events = [ev])

    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            asyncio.run(
                inf_mod.install_latest_transformers_route(
                    InstallLatestTransformersRequest(version = "5.0.0"),
                    "tester",
                )
            )
        assert not ev.is_set()
        assert active_generations.count() == 1

    assert exc.value.status_code == 409
    assert calls["installed"] == []


def test_a_confirmed_install_that_cannot_drain_refuses_instead_of_swapping(monkeypatch):
    # A cancelled request that never observes its event keeps the in-flight count up, so the drain is
    # bounded and cannot wedge the process holding the gate; the recheck behind it still refuses.
    _route_gate()
    import asyncio

    from fastapi import HTTPException

    from models.inference import InstallLatestTransformersRequest

    ev = threading.Event()
    stuck = threading.Event()
    stuck.set()  # already "cancelled", yet still counted: it never unwinds
    inf_mod, calls = _stub_install_route(monkeypatch, in_flight_events = [ev, stuck])
    monkeypatch.setattr(inf_mod, "_POST_CANCEL_DRAIN_TIMEOUT_S", 0.05)

    def _never_unwinds(current_request_counted = True, *, include_pending = True):
        return 1

    import core.inference.llama_keepwarm as keepwarm

    monkeypatch.setattr(keepwarm, "other_inference_request_count", _never_unwinds)

    async def _install():
        # Deadline here too: a regression that drops the drain's bound must fail, not hang the suite.
        return await asyncio.wait_for(
            inf_mod.install_latest_transformers_route(
                InstallLatestTransformersRequest(version = "5.0.0", force_cancel_active = True),
                "tester",
            ),
            timeout = 5,
        )

    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            asyncio.run(_install())

    assert exc.value.status_code == 409
    assert calls["installed"] == []


def test_confirmed_install_does_not_spend_its_cancel_on_an_install_that_will_refuse(monkeypatch):
    # An unrelated counted request the cancel cannot stop must be waited out BEFORE the cancel: the
    # recheck refuses while it is there, so cancelling first stopped chats for a doomed install.
    _route_gate()
    import asyncio

    from fastapi import HTTPException

    from models.inference import InstallLatestTransformersRequest

    ev = threading.Event()
    inf_mod, calls = _stub_install_route(monkeypatch, in_flight_events = [ev])

    import core.inference.llama_keepwarm as keepwarm

    def _never_drains(current_request_counted = True, *, include_pending = True):
        # Discounting the registered chat still leaves the counted-only stranger: the drain must not clear.
        return 2

    monkeypatch.setattr(keepwarm, "other_inference_request_count", _never_drains)
    monkeypatch.setattr(inf_mod, "_POST_CANCEL_DRAIN_TIMEOUT_S", 0.05)

    async def _install():
        return await asyncio.wait_for(
            inf_mod.install_latest_transformers_route(
                InstallLatestTransformersRequest(version = "5.0.0", force_cancel_active = True),
                "tester",
            ),
            timeout = 5,
        )

    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        with pytest.raises(HTTPException) as exc:
            asyncio.run(_install())
        # The refusal is the same as before; what changed is that the chat lives.
        assert not ev.is_set()
        assert active_generations.count() == 1

    assert exc.value.status_code == 409
    assert calls["installed"] == []


# ── draining before teardown ──────────────────────────────────────────


def _drain_with_counts(monkeypatch, counts, **kwargs):
    """Run _wait_for_model_switch_idle against a scripted in-flight count.

    ``counts`` is consumed one entry per poll; the last value repeats, so a
    trailing non-zero stands for a request that never unwinds.
    """
    _route_gate()
    import asyncio

    import core.inference.llama_keepwarm as keepwarm
    import routes.inference as inf_mod

    remaining = list(counts)
    polls = {"n": 0}

    def _count(current_request_counted = True, *, include_pending = True):
        polls["n"] += 1
        return remaining.pop(0) if len(remaining) > 1 else remaining[0]

    monkeypatch.setattr(keepwarm, "other_inference_request_count", _count)
    monkeypatch.setattr(inf_mod, "_switch_waiter_count", lambda: 0)

    async def _run():
        # Hard test-side deadline: a drain that regresses to waiting forever must fail red, not hang.
        await asyncio.wait_for(
            inf_mod._wait_for_model_switch_idle(current_request_counted = False, **kwargs),
            timeout = 5,
        )

    asyncio.run(_run())
    return polls["n"]


def test_forced_swap_does_not_wait_out_the_generations_it_is_about_to_cancel(monkeypatch):
    # cancel_pending discounts the registered generations, since the caller cancels them right after.
    # Drop the discount and the drain waits on a count only that pending cancel can lower: forever.
    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        polls = _drain_with_counts(monkeypatch, [1], cancel_pending = True)
    assert polls == 1


def test_the_same_drain_without_the_discount_would_keep_waiting(monkeypatch):
    # The other half: that count really does block, so the previous test passes by the discount.
    ev = threading.Event()
    with active_generations.ActiveGeneration(ev, thread_id = "t1"):
        polls = _drain_with_counts(monkeypatch, [1], timeout_s = 0.05)
    assert polls > 1


def test_post_cancel_drain_gives_up_on_a_request_that_never_unwinds(monkeypatch):
    # TTS on the subprocess backend observes no cancel event, so a forced swap can cancel it and still
    # see it counted forever. The post-cancel drains hold the gate, so they must expire and proceed.
    polls = _drain_with_counts(monkeypatch, [1], timeout_s = 0.05)
    assert polls > 1


def test_drain_returns_as_soon_as_the_cancelled_requests_unwind(monkeypatch):
    # The bound is a backstop: once the count drops the drain returns without sitting out the timeout.
    polls = _drain_with_counts(monkeypatch, [2, 1, 0], timeout_s = 30)
    assert polls == 3


# ── queued chats must not cancel the running one ──────────────────────


def _orchestrator_for_ownership():
    """A real InferenceOrchestrator with just enough stubbed to drive the lock."""
    _route_gate()
    orch_mod = pytest.importorskip(
        "core.inference.orchestrator", reason = "inference stack not installed"
    )
    orch = orch_mod.InferenceOrchestrator.__new__(orch_mod.InferenceOrchestrator)
    orch._gen_lock = threading.Lock()
    orch._active_cancel_events = []
    orch._executing_cancel_events = []
    orch._active_cancel_lock = threading.Lock()
    orch._cancel_event = threading.Event()
    orch._ensure_subprocess_alive = lambda: False  # stop before _send_cmd
    return orch


def test_a_queued_chat_cannot_reset_the_chat_that_is_generating():
    # Safetensors generation serialises on _gen_lock and the worker has ONE cancel event: stopping
    # queued chat B reset that shared event and killed running chat A. Scope the reset to the holder.
    orch = _orchestrator_for_ownership()
    a_event = threading.Event()
    b_event = threading.Event()

    orch._claim_worker(a_event)  # A holds the lock ...
    orch._mark_worker_started(a_event)  # ... and the worker is answering it
    orch.reset_generation_state(b_event)  # B is queued and gets stopped
    assert not orch._cancel_event.is_set()

    orch.reset_generation_state(a_event)  # A's own Stop still works
    assert orch._cancel_event.is_set()


def test_a_global_reset_still_cancels_whatever_is_running():
    # Unload and switch pass nothing: they mean stop everything, else a generation survives teardown.
    orch = _orchestrator_for_ownership()
    _running = threading.Event()
    orch._claim_worker(_running)
    orch._mark_worker_started(_running)
    orch.reset_generation_state()
    assert orch._cancel_event.is_set()


def test_a_reset_with_no_generation_running_is_not_dropped():
    # Nothing holds the lock, so no chat to protect: a reset before any generation must still run.
    orch = _orchestrator_for_ownership()
    orch.reset_generation_state(threading.Event())
    assert orch._cancel_event.is_set()


def test_unload_waits_for_a_request_that_is_admitted_but_not_yet_registered(monkeypatch):
    # The window between the keep-warm middleware and _TrackedCancel: counted in-flight, absent from
    # the registry. Cancelling on the registry alone tore the backend down under an admitted request.
    _route_gate()
    import core.inference.llama_keepwarm as keepwarm
    import routes.inference as inf_mod

    # Counted for two polls, then the request registers/finishes and clears.
    remaining = [1, 1, 0]
    seen = {}

    def _count(current_request_counted = True, *, include_pending = True):
        return remaining.pop(0) if len(remaining) > 1 else remaining[0]

    monkeypatch.setattr(keepwarm, "other_inference_request_count", _count)
    monkeypatch.setattr(inf_mod, "_switch_waiter_count", lambda: 0)

    torn_down: list[str] = []

    def _record_teardown():
        seen["counted_at_teardown"] = remaining[0]
        torn_down.append("gguf")

    # Registry deliberately empty: this is the unregistered case.
    response = _run_unload(
        inf_mod,
        monkeypatch,
        loaded_gguf = "org/A-GGUF",
        requested = "org/A-GGUF",
        force = True,
        torn_down = torn_down,
        unload_model = _record_teardown,
    )

    assert active_generations.count() == 0
    assert torn_down == ["gguf"]
    assert seen["counted_at_teardown"] == 0
    assert response.status == "unloaded"


def test_a_dispatched_chat_cannot_reset_its_concurrently_dispatched_sibling():
    # Compare-mode / dispatched runs bypass _gen_lock and run concurrently, so with several claimed
    # at once a Stop on one must still leave the others alone.
    orch = _orchestrator_for_ownership()
    a_event = threading.Event()
    b_event = threading.Event()
    c_event = threading.Event()

    orch._claim_worker(a_event)
    orch._mark_worker_started(a_event)
    orch._claim_worker(b_event)
    orch._mark_worker_started(b_event)

    orch.reset_generation_state(c_event)  # a third, unrelated request
    assert not orch._cancel_event.is_set()

    orch.reset_generation_state(b_event)  # one of the running pair
    assert orch._cancel_event.is_set()


def test_releasing_one_generation_leaves_the_other_claimed():
    orch = _orchestrator_for_ownership()
    a_event = threading.Event()
    b_event = threading.Event()
    orch._claim_worker(a_event)
    orch._mark_worker_started(a_event)
    orch._claim_worker(b_event)
    orch._mark_worker_started(b_event)
    orch._release_worker(a_event)

    orch.reset_generation_state(a_event)  # now a stranger
    assert not orch._cancel_event.is_set()

    orch._release_worker(b_event)
    orch.reset_generation_state(a_event)  # nothing running: no one to protect
    assert orch._cancel_event.is_set()


def test_a_dispatched_request_queued_behind_another_is_not_an_owner():
    # The subprocess runs generations one at a time, so admission is not execution: B can be claimed
    # while the worker answers A. Counting B as an owner let its Stop signal the shared event and end A.
    orch = _orchestrator_for_ownership()
    a_event = threading.Event()
    b_event = threading.Event()

    orch._claim_worker(a_event)
    orch._mark_worker_started(a_event)  # the worker answered A
    orch._claim_worker(b_event)  # B is only queued behind it

    orch.reset_generation_state(b_event)
    assert not orch._cancel_event.is_set(), "a queued request must not reset A"

    orch._mark_worker_started(b_event)  # the worker moves on to B
    orch.reset_generation_state(b_event)
    assert orch._cancel_event.is_set()


def test_a_queued_request_cannot_reset_during_the_other_ones_prefill():
    # Between _send_cmd and the first response A is claimed but not executing; treating that as
    # "nobody to protect" let a queued request's Stop kill A mid-prefill.
    orch = _orchestrator_for_ownership()
    a_event = threading.Event()
    b_event = threading.Event()

    orch._claim_worker(a_event)  # A sent its command and is in prefill
    orch._claim_worker(b_event)  # B is queued behind it

    orch.reset_generation_state(b_event)
    assert not orch._cancel_event.is_set(), "B must not reset A during prefill"

    # A's own Stop still works before any token has arrived.
    orch.reset_generation_state(a_event)
    assert orch._cancel_event.is_set()


def test_the_oldest_claim_is_the_one_the_worker_is_prefilling():
    # The command queue is FIFO, so with nothing answering the oldest claim is the executor.
    orch = _orchestrator_for_ownership()
    a_event = threading.Event()
    b_event = threading.Event()
    orch._claim_worker(a_event)
    orch._claim_worker(b_event)
    orch._release_worker(a_event)

    orch.reset_generation_state(b_event)
    assert orch._cancel_event.is_set(), "B is now the oldest claim"


def test_claim_order_matches_send_order_under_concurrent_dispatch():
    # _owns_worker reads claim order to decide who is prefilling, so a claim not atomic with the
    # enqueue can put A first in the list while B is first in the subprocess queue: stopping A kills B.
    _route_gate()
    orch_mod = pytest.importorskip(
        "core.inference.orchestrator", reason = "inference stack not installed"
    )
    orch = orch_mod.InferenceOrchestrator.__new__(orch_mod.InferenceOrchestrator)
    orch._active_cancel_events = []
    orch._executing_cancel_events = []
    orch._active_cancel_lock = threading.Lock()
    orch._send_order_lock = threading.Lock()

    sent: list = []
    barrier = threading.Barrier(4)

    def worker(ev):
        barrier.wait(timeout = 10)
        with orch._send_order_lock:
            orch._claim_worker(ev)
            # Stand in for _send_cmd: the enqueue must not be separable from the claim.
            sent.append(ev)

    events = [threading.Event() for _ in range(4)]
    threads = [threading.Thread(target = worker, args = (e,)) for e in events]
    for t in threads:
        t.start()
    for t in threads:
        t.join(timeout = 30)

    assert orch._active_cancel_events == sent, "claim order must equal send order"