Merge pull request #41120 from BerriAI/litellm_trace_profiler_threads

refactor(harness): expand independent trace coverage

litellm-rust/crates/ai-gateway/src/bin/trace_parity_gateway.rs

@@ -5,6 +5,7 @@ use serde_json::Value;
 
 #[derive(Deserialize)]
 struct Input {
+    path: String,
     model_alias: String,
     provider_model: String,
     api_base: String,
@@ -21,7 +22,8 @@ async fn main() {
         Ok(input) => input,
         Err(error) => fail(error),
     };
-    let result = litellm_ai_gateway::trace_parity::traced_messages_request(
+    let result = litellm_ai_gateway::trace_parity::traced_request(
+        input.path,
         input.model_alias,
         input.provider_model,
         input.api_base,

litellm-rust/crates/ai-gateway/src/trace_parity.rs

@@ -29,14 +29,15 @@ pub struct TracedGatewayResponse {
     pub trace: Vec<litellm_core::observability::FunctionTraceEvent>,
 }
 
-pub async fn traced_messages_request(
+pub async fn traced_request(
+    path: String,
     model_alias: String,
     provider_model: String,
     api_base: String,
     body: Value,
 ) -> TracedGatewayResponse {
     let trace = litellm_core::observability::FunctionTrace::default();
-    let result = messages_request(model_alias, provider_model, api_base, body)
+    let result = request(path, model_alias, provider_model, api_base, body)
         .with_subscriber(trace.dispatcher())
         .await;
     let events = trace.events();
@@ -54,7 +55,8 @@ pub async fn traced_messages_request(
     }
 }
 
-pub async fn messages_request(
+pub async fn request(
+    path: String,
     model_alias: String,
     provider_model: String,
     api_base: String,
@@ -75,7 +77,7 @@ pub async fn messages_request(
     };
     let request = Request::builder()
         .method("POST")
-        .uri("/v1/messages")
+        .uri(path)
         .header(AUTHORIZATION, "Bearer trace-master-key")
         .header(CONTENT_TYPE, "application/json")
         .body(Body::from(body.to_string()))

tests/rust-python-harness/AGENTS.md

@@ -63,7 +63,7 @@ tests/rust-python-harness/
 - Examples: `run e2e_parity --surface sdk --function ocr`, `run unit_tests_parity --function ocr --pytest-arg=-x`, or `run all --function ocr`
 - `cli/catalog.py` discovers strategies, validates their Python definitions, and orders them; `cli/__init__.py` builds the Click command tree; `cli/commands.py` runs selected cases
 - `e2e_parity/` compares SDK objects, exceptions, callbacks, and streams, or gateway HTTP responses
-- `trace_parity/` compares mapped operations, call counts, and required execution ordering; before running it rebuilds the native bridge with the `trace-parity` feature whenever `litellm-rust` sources are newer than the installed extension (`shared/native_build.py`)
+- `trace_parity/` prints every collected Python call under `litellm/` and every Rust span without comparing them; mappings only filter the separate unit-test mapping strategy. Before running it rebuilds the native bridge with the `trace-parity` feature whenever `litellm-rust` sources are newer than the installed extension (`shared/native_build.py`)
 - E2E and trace strategies load their registered module cases and run surface-specific execution from their folders
 - `unit_tests_mapping/contracts.py` owns typed harness-side mapping contracts, per-function contracts live below `cases/`, and `mappings.py` exports the registry; live test discovery derives unmapped Python and Rust-only tests without an exhaustive manifest
 - `unit_tests_mapping/runner.py` validates confirmed mappings against the live Python and Rust inventories and attaches the derived status report

tests/rust-python-harness/cli/__init__.py

@@ -58,16 +58,29 @@ def _strategy_command(strategy: Strategy) -> click.Command:
                 help=runner_argument.help,
             )
         )
+    for runner_option in strategy.definition.runner_options:
+        name: Final = runner_option.option.removeprefix("--").replace("-", "_")
+        params.append(
+            click.Option(
+                (runner_option.option, name),
+                type=click.Choice(runner_option.choices),
+                help=runner_option.help,
+            )
+        )
 
     def run_strategy(
         sdk_functions: tuple[str, ...],
         surface: str | None = None,
         runner_args: tuple[str, ...] = (),
+        **runner_options: str | None,
     ) -> int:
         selected_functions: Final = cast(frozenset[SdkFunction], frozenset(sdk_functions))
         selected_surface: Final = cast(Surface | None, surface)
         cases: Final = select_cases((strategy,), selected_functions, selected_surface)
-        return run_command((strategy,), cases, runner_args)
+        option_args: Final = tuple(
+            f"--{name.replace('_', '-')}={value}" for name, value in runner_options.items() if value is not None
+        )
+        return run_command((strategy,), cases, (*runner_args, *option_args))
 
     return click.Command(
         strategy.id,

tests/rust-python-harness/cli/catalog.py

@@ -21,9 +21,7 @@ def _load_strategy_module(name: str, folder: Path, prefix: str | None) -> Module
     if prefix is not None:
         return importlib.import_module(f"{prefix}.{name}")
     module_name: Final = _synthetic_module_name(folder)
-    spec: Final = importlib.util.spec_from_file_location(
-        module_name, folder / "__init__.py"
-    )
+    spec: Final = importlib.util.spec_from_file_location(module_name, folder / "__init__.py")
     if spec is None or spec.loader is None:
         raise ValueError(f"{folder}: cannot load strategy package")
     module: Final = importlib.util.module_from_spec(spec)
@@ -59,9 +57,7 @@ def _load_strategy(name: str, folder: Path, prefix: str | None) -> Strategy:
     if duplicates:
         raise ValueError(f"{folder}: duplicate strategy cases: {duplicates}")
     expected: Final = frozenset(
-        (surface, function)
-        for surface in (definition.surfaces or (None,))
-        for function in SDK_FUNCTIONS
+        (surface, function) for surface in (definition.surfaces or (None,)) for function in SDK_FUNCTIONS
     )
     actual: Final = frozenset(keys)
     if actual != expected:
@@ -73,8 +69,7 @@ def _load_strategy(name: str, folder: Path, prefix: str | None) -> Strategy:
     incompatible: Final = tuple(
         (case.surface, case.sdk_function)
         for case in definition.cases
-        if case.spec.disposition is CaseDisposition.RUNNABLE
-        and not isinstance(case.spec, definition.runnable_spec)
+        if case.spec.disposition is CaseDisposition.RUNNABLE and not isinstance(case.spec, definition.runnable_spec)
     )
     if incompatible:
         raise ValueError(f"{folder}: runnable cases do not match {definition.runnable_spec.__name__}: {incompatible}")
@@ -102,14 +97,10 @@ def _load_strategy(name: str, folder: Path, prefix: str | None) -> Strategy:
 def load_catalog(root: Path | None = None) -> tuple[Strategy, ...]:
     resolved: Final = STRATEGIES_ROOT if root is None else root
     prefix: Final = _STRATEGIES_PACKAGE.__name__ if resolved == STRATEGIES_ROOT else None
-    folders: Final = tuple(
-        info.name for info in pkgutil.iter_modules([str(resolved)]) if info.ispkg
-    )
+    folders: Final = tuple(info.name for info in pkgutil.iter_modules([str(resolved)]) if info.ispkg)
     if not folders:
         raise ValueError(f"No strategy packages found below {resolved}")
-    strategies: Final = tuple(
-        _load_strategy(name, resolved / name, prefix) for name in sorted(folders)
-    )
+    strategies: Final = tuple(_load_strategy(name, resolved / name, prefix) for name in sorted(folders))
     ids: Final = [strategy.id for strategy in strategies]
     if len(set(ids)) != len(ids):
         raise ValueError(f"Duplicate strategy id in {resolved}")

tests/rust-python-harness/cli/commands.py

@@ -21,8 +21,7 @@ def select_cases(
         case
         for strategy in strategies
         for case in strategy.cases
-        if (not sdk_functions or case.sdk_function in sdk_functions)
-        and (surface is None or case.surface == surface)
+        if (not sdk_functions or case.sdk_function in sdk_functions) and (surface is None or case.surface == surface)
     )
 
 
@@ -32,8 +31,7 @@ def run_command(
     runner_args: Sequence[str] = (),
 ) -> int:
     grouped: Final = {
-        strategy.id: tuple(case for case in cases if case.strategy_id == strategy.id)
-        for strategy in strategies
+        strategy.id: tuple(case for case in cases if case.strategy_id == strategy.id) for strategy in strategies
     }
     visible: Final = tuple(strategy for strategy in strategies if grouped[strategy.id])
     runners: Final = tuple(replace(strategy, cases=grouped[strategy.id]) for strategy in visible)

tests/rust-python-harness/cli/test_cli.py

@@ -242,7 +242,7 @@ def _assert_unavailable_cell(strategy: Strategy, case: HarnessCase, section_titl
 def test_every_unavailable_case_finishes_and_explains_itself() -> None:
     section_titles: Final = {
         "e2e_parity": "End-to-end parity outcomes",
-        "trace_parity": "trace comparisons",
+        "trace_parity": "traces",
         "unit_tests_mapping": "Python/Rust unit-test mappings",
         "unit_tests_parity": "Python backend parity outcomes",
         "unit_tests_rust": "Native Rust unit-test outcomes",
@@ -359,6 +359,25 @@ def test_strategy_command_forwards_repeated_filters_and_runner_arguments(
     ]
 
 
+def test_trace_command_forwards_engine_and_scenario(monkeypatch: pytest.MonkeyPatch) -> None:
+    cli: Final = importlib.import_module("tests.rust-python-harness.cli")
+    captured: list[tuple[str, ...]] = []
+
+    def capture_run(
+        strategies: Sequence[Strategy],
+        cases: Sequence[HarnessCase],
+        runner_args: Sequence[str] = (),
+    ) -> int:
+        del strategies, cases
+        captured.append(tuple(runner_args))
+        return 0
+
+    monkeypatch.setattr(cli, "run_command", capture_run)
+
+    assert main(["run", "trace_parity", "--scenario", "async-mistral", "--engine", "python"]) == 0
+    assert captured == [("async-mistral", "--engine=python")]
+
+
 def test_omitted_surface_selects_every_strategy_surface(monkeypatch: pytest.MonkeyPatch) -> None:
     cli: Final = importlib.import_module("tests.rust-python-harness.cli")
     selected: list[str] = []

tests/rust-python-harness/conftest.py

@@ -19,9 +19,7 @@ def subprocess_test_environment(monkeypatch: pytest.MonkeyPatch) -> None:
 def cargo_project(tmp_path: Path) -> Callable[[str, str], Path]:
     def create(package: str, source: str) -> Path:
         manifest: Final = tmp_path / "Cargo.toml"
-        manifest.write_text(
-            f'[package]\nname = "{package}"\nversion = "0.1.0"\nedition = "2021"\n[workspace]\n'
-        )
+        manifest.write_text(f'[package]\nname = "{package}"\nversion = "0.1.0"\nedition = "2021"\n[workspace]\n')
         (tmp_path / "src").mkdir()
         (tmp_path / "src/lib.rs").write_text(source)
         return manifest

tests/rust-python-harness/shared/native_build.py

@@ -16,6 +16,11 @@ _RUST_ROOT: Final = "litellm-rust"
 _LOCKFILE: Final = "Cargo.lock"
 _SOURCE_SUFFIXES: Final = frozenset({".rs", ".toml"})
 _FAILURE_OUTPUT_LINES: Final = 15
+_TRACE_CHECK: Final = (
+    "from litellm.rust_bridge import get_native_bridge; "
+    "bridge = get_native_bridge(); "
+    "raise SystemExit(0 if bridge is not None and getattr(bridge, '_trace', None) is not None else 1)"
+)
 
 
 def needs_rebuild(native_mtime: float | None, newest_source_mtime: float | None) -> bool:
@@ -73,6 +78,17 @@ def _rebuild(repo_root: Path) -> tuple[bool, str]:
     return completed.returncode == 0, "\n".join(lines[-_FAILURE_OUTPUT_LINES:])
 
 
+def _installed_bridge_has_trace(repo_root: Path) -> bool:
+    completed: Final = subprocess.run(
+        (sys.executable, "-c", _TRACE_CHECK),
+        cwd=repo_root,
+        stdout=subprocess.DEVNULL,
+        stderr=subprocess.DEVNULL,
+        check=False,
+    )
+    return completed.returncode == 0
+
+
 def trace_bridge_error() -> str | None:
     bridge: Final = get_native_bridge()
     if bridge is None:
@@ -85,7 +101,10 @@ def trace_bridge_error() -> str | None:
 def ensure_trace_bridge(repo_root: Path) -> str | None:
     native_path: Final = _native_module_path()
     native_mtime: Final = native_path.stat().st_mtime if native_path is not None and native_path.exists() else None
-    if needs_rebuild(native_mtime, _newest_source_mtime(repo_root)):
+    rebuild_required: Final = needs_rebuild(
+        native_mtime, _newest_source_mtime(repo_root)
+    ) or not _installed_bridge_has_trace(repo_root)
+    if rebuild_required:
         print(f"Rebuilding native Rust bridge ({BRIDGE_FEATURE} feature)...", flush=True)
         succeeded: Final
         output: Final

tests/rust-python-harness/shared/parity/fixtures/recording.py

@@ -191,6 +191,7 @@ class _RecordingHandler(LocalHttpHandler):
         self.end_headers()
         self.wfile.write(body)
 
+
 def _recording_provider(spec: UpstreamEndpoint) -> AbstractContextManager[_RecordingProvider]:
     return serve_in_thread(_RecordingProvider(spec))
 

tests/rust-python-harness/shared/parity/fixtures/store.py

@@ -15,6 +15,8 @@ from .cassette import deserialize_cassette, serialize_cassette
 from .recording import RecordedInteraction
 
 FIXTURE_SCHEMA_VERSION: Final = 1
+
+
 class FixtureInput(Protocol):
     def canonical_input(self) -> dict[str, object]: ...
 

tests/rust-python-harness/shared/parity/fixtures/test_pipeline.py

@@ -45,8 +45,8 @@ class _Upstream(LocalHttpServer):
         super().__init__(("127.0.0.1", 0), _UpstreamHandler)
         self.response_status: Final = status
 
-class _UpstreamHandler(LocalHttpHandler):
 
+class _UpstreamHandler(LocalHttpHandler):
     def do_POST(self) -> None:
         length: Final = int(self.headers.get("content-length") or "0")
         self.rfile.read(length)
@@ -59,6 +59,7 @@ class _UpstreamHandler(LocalHttpHandler):
         self.end_headers()
         self.wfile.write(body)
 
+
 def _upstream(status: int = 200) -> AbstractContextManager[_Upstream]:
     return serve_in_thread(_Upstream(status))
 

tests/rust-python-harness/shared/parity/fixtures/test_recording.py

@@ -238,6 +238,7 @@ class _ControlledUpstreamHandler(LocalHttpHandler):
         self.end_headers()
         self.wfile.write(body)
 
+
 def _controlled_upstream(
     stream_chunks: tuple[bytes, ...] = _SSE_CHUNKS,
 ) -> AbstractContextManager[_ControlledUpstream]:

tests/rust-python-harness/shared/reporting/models.py

@@ -180,15 +180,11 @@ class HarnessRun:
 
     @property
     def unique_checks(self) -> int:
-        return len(
-            {nodeid for result in self.results.values() for nodeid in result.collected}
-        )
+        return len({nodeid for result in self.results.values() for nodeid in result.collected})
 
     @property
     def completed_checks(self) -> int:
-        return len(
-            {nodeid for result in self.results.values() for nodeid in result.completed}
-        )
+        return len({nodeid for result in self.results.values() for nodeid in result.completed})
 
     @classmethod
     def from_cases(cls, cases: Iterable[HarnessCase]) -> HarnessRun:

tests/rust-python-harness/shared/reporting/strategy.py

@@ -67,6 +67,13 @@ class RunnerArgumentDefinition:
     metavar: str = "ARG"
 
 
+@dataclass(frozen=True, slots=True)
+class RunnerOptionDefinition:
+    option: str
+    help: str
+    choices: tuple[str, ...]
+
+
 class StrategyRunner(Protocol):
     def __call__(
         self,
@@ -90,3 +97,4 @@ class StrategyDefinition:
     render: StrategyRenderer
     surfaces: tuple[Surface, ...] = ()
     runner_argument: RunnerArgumentDefinition | None = None
+    runner_options: tuple[RunnerOptionDefinition, ...] = ()

tests/rust-python-harness/shared/test_native_build.py

@@ -89,8 +89,8 @@ def test_ensure_trace_bridge_reports_failed_rebuild(tmp_path: Final, monkeypatch
     assert "boom" in message
 
 
-def test_ensure_trace_bridge_flags_missing_trace_feature_without_rebuild(
-    tmp_path: Final, monkeypatch: pytest.MonkeyPatch
+def test_ensure_trace_bridge_rebuilds_when_trace_feature_is_missing(
+    tmp_path: Final, monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]
 ) -> None:
     native: Final = tmp_path / "_native.abi3.so"
     native.write_bytes(b"")
@@ -105,12 +105,17 @@ def test_ensure_trace_bridge_flags_missing_trace_feature_without_rebuild(
         state.rebuilt = True
         return True, ""
 
+    def fake_get_native_bridge() -> SimpleNamespace:
+        assert state.rebuilt
+        return SimpleNamespace(_trace=object())
+
     monkeypatch.setattr(native_build, "_native_module_path", lambda: native)
     monkeypatch.setattr(native_build, "_rebuild", fake_rebuild)
-    monkeypatch.setattr(native_build, "get_native_bridge", lambda: SimpleNamespace(_trace=None))
+    monkeypatch.setattr(native_build, "_installed_bridge_has_trace", lambda repo_root: False)
+    monkeypatch.setattr(native_build, "get_native_bridge", fake_get_native_bridge)
 
     message: Final = native_build.ensure_trace_bridge(tmp_path)
 
-    assert message is not None
-    assert "_trace" in message
-    assert state.rebuilt is False
+    assert message is None
+    assert state.rebuilt is True
+    assert "Rebuilding native Rust bridge" in capsys.readouterr().out

tests/rust-python-harness/shared/tracing/profiler.py

@@ -2,7 +2,8 @@ from __future__ import annotations
 
 import sys
 import threading
-from collections.abc import Generator, Iterator, Mapping
+import warnings
+from collections.abc import Callable, Generator, Iterator, Mapping
 from contextlib import contextmanager
 from dataclasses import dataclass
 from functools import lru_cache
@@ -32,6 +33,7 @@ class PythonProfiler:
         self._source_root: Final = str(source_root.resolve()) + "/"
         self._seen_frames: Final[set[FrameType]] = set()
         self._event_ids: Final[dict[FrameType, int]] = {}
+        self._lock: Final = threading.Lock()
         self.events: Final[list[FunctionTraceEvent]] = []
 
     def __call__(self, frame: FrameType, event: str, _arg: object) -> None:
@@ -40,14 +42,15 @@ class PythonProfiler:
         function_name: Final = self.function_name(frame)
         if function_name is None:
             return
-        event_id: Final = len(self.events)
-        parent_id: Final = next(
-            (self._event_ids[ancestor] for ancestor in _frame_ancestors(frame) if ancestor in self._event_ids),
-            None,
-        )
-        self._seen_frames.add(frame)
-        self._event_ids[frame] = event_id
-        self.events.append(FunctionTraceEvent(id=event_id, parent_id=parent_id, function=function_name))
+        with self._lock:
+            event_id: Final = len(self.events)
+            parent_id: Final = next(
+                (self._event_ids[ancestor] for ancestor in _frame_ancestors(frame) if ancestor in self._event_ids),
+                None,
+            )
+            self._seen_frames.add(frame)
+            self._event_ids[frame] = event_id
+            self.events.append(FunctionTraceEvent(id=event_id, parent_id=parent_id, function=function_name))
 
     def function_name(self, frame: FrameType) -> str | None:
         code: Final = frame.f_code
@@ -137,21 +140,51 @@ def _frame_ancestors(frame: FrameType) -> Generator[FrameType]:
 
 
 @contextmanager
-def profile_python(source_root: Path, *, threads: bool = False) -> Generator[PythonProfiler]:
-    profiler: Final = PythonProfiler(source_root)
+def _installed_profiler(profiler: Callable[[FrameType, str, object], None], *, threads: bool) -> Generator[None]:
+    if threads and sys.version_info >= (3, 12):
+        tool_id: Final = next((slot for slot in (2, 3, 4, 0, 1, 5) if sys.monitoring.get_tool(slot) is None), None)
+        if tool_id is None:
+            raise RuntimeError("no sys.monitoring tool ID is available for Python trace collection")
+
+        def started(_code: CodeType, _offset: int) -> None:
+            profiler(sys._getframe(1), "call", None)
+
+        sys.monitoring.use_tool_id(tool_id, "litellm-python-trace")
+        try:
+            sys.monitoring.register_callback(tool_id, sys.monitoring.events.PY_START, started)
+            sys.monitoring.set_events(tool_id, sys.monitoring.events.PY_START)
+            yield
+        finally:
+            sys.monitoring.set_events(tool_id, 0)
+            sys.monitoring.register_callback(tool_id, sys.monitoring.events.PY_START, None)
+            sys.monitoring.free_tool_id(tool_id)
+        return
+    if threads:
+        warnings.warn(
+            "Python <3.12 cannot trace existing worker threads; use Python 3.12+ for complete threaded traces",
+            RuntimeWarning,
+            stacklevel=3,
+        )
     previous_thread: Final = threading.getprofile()
     if threads:
         threading.setprofile(profiler)
     previous: Final = sys.getprofile()
     sys.setprofile(profiler)
     try:
-        yield profiler
+        yield
     finally:
         sys.setprofile(previous)
         if threads:
             threading.setprofile(previous_thread)
 
 
+@contextmanager
+def profile_python(source_root: Path, *, threads: bool = False) -> Generator[PythonProfiler]:
+    profiler: Final = PythonProfiler(source_root)
+    with _installed_profiler(profiler, threads=threads):
+        yield profiler
+
+
 @contextmanager
 def profile_python_function_usage(
     source_root: Path,
@@ -160,14 +193,5 @@ def profile_python_function_usage(
     threads: bool = False,
 ) -> Generator[PythonFunctionUsageProfiler]:
     profiler: Final = PythonFunctionUsageProfiler(source_root, functions)
-    previous_thread: Final = threading.getprofile()
-    if threads:
-        threading.setprofile(profiler)
-    previous: Final = sys.getprofile()
-    sys.setprofile(profiler)
-    try:
+    with _installed_profiler(profiler, threads=threads):
         yield profiler
-    finally:
-        sys.setprofile(previous)
-        if threads:
-            threading.setprofile(previous_thread)

tests/rust-python-harness/shared/tracing/steps.py

@@ -76,7 +76,7 @@ def _span_for(engine: Engine, function: str, mappings: Sequence[TraceMapping]) -
 
 
 def pipeline_projection(
-    engine: Engine, events: Sequence[FunctionTraceEvent], mappings: Sequence[TraceMapping]
+    engine: Engine, events: Sequence[FunctionTraceEvent], mappings: Sequence[TraceMapping] | None = None
 ) -> PipelineProjection:
     raw_parents: dict[int, int | None] = {}
     projected_ids: set[int] = set()
@@ -88,7 +88,7 @@ def pipeline_projection(
         if event.parent_id is not None and event.parent_id not in raw_parents:
             raise ValueError(f"trace event {event.id} references unknown or later parent {event.parent_id}")
         raw_parents[event.id] = event.parent_id
-        span = _span_for(engine, event.function, mappings)
+        span = event.function if mappings is None else _span_for(engine, event.function, mappings)
         if span is None:
             unmatched += 1
             continue
@@ -181,12 +181,7 @@ class TraceDiff:
 
     @property
     def matches(self) -> bool:
-        return (
-            not self.python_only
-            and not self.rust_only
-            and not self.missing_mappings
-            and self.shared_order_matches
-        )
+        return not self.python_only and not self.rust_only and not self.missing_mappings and self.shared_order_matches
 
 
 def _missing_mappings(
@@ -257,9 +252,7 @@ def trace_diff(
     rust_counts: Final = Counter(rust_spans)
     python_only_counts: Final = python_counts - rust_counts
     rust_only_counts: Final = rust_counts - python_counts
-    python_only: Final = tuple(
-        span for span, count in python_only_counts.items() for _ in range(count)
-    )
+    python_only: Final = tuple(span for span, count in python_only_counts.items() for _ in range(count))
     rust_only: Final = tuple(span for span, count in rust_only_counts.items() for _ in range(count))
     first_difference: Final = _first_difference(python, rust, mappings, contract)
     return TraceDiff(

tests/rust-python-harness/shared/tracing/test_profiler.py

@@ -4,9 +4,10 @@ import asyncio
 import sys
 import threading
 from collections.abc import Callable
+from concurrent.futures import ThreadPoolExecutor
 from functools import wraps
 from pathlib import Path
-from types import FunctionType
+from types import FrameType, FunctionType
 from typing import Final, ParamSpec, TypeVar, cast
 
 import pytest
@@ -41,11 +42,12 @@ def _events_named(profiler: PythonProfiler, name: str) -> tuple[FunctionTraceEve
     return tuple(event for event in profiler.events if event.function.endswith(name))
 
 
-def test_profiler_keeps_repeated_calls() -> None:
+@pytest.mark.parametrize("threads", (False, True))
+def test_profiler_keeps_repeated_calls(threads: bool) -> None:
     def called() -> None:
         return None
 
-    with profile_python(Path(__file__).parent) as profiler:
+    with profile_python(Path(__file__).parent, threads=threads) as profiler:
         called()
         called()
 
@@ -60,14 +62,15 @@ def test_profiler_qualifies_decorated_methods_by_class() -> None:
     assert _module_qualnames(__name__)[cast(FunctionType, Decorated.call.__wrapped__).__code__] == "Decorated.call"
 
 
-def test_profiler_records_real_frame_ancestry() -> None:
+@pytest.mark.parametrize("threads", (False, True))
+def test_profiler_records_real_frame_ancestry(threads: bool) -> None:
     def called() -> None:
         return None
 
     def outer() -> None:
         called()
 
-    with profile_python(Path(__file__).parent) as profiler:
+    with profile_python(Path(__file__).parent, threads=threads) as profiler:
         outer()
 
     outer_event, called_event = (event for event in profiler.events if event.function.endswith(("outer", "called")))
@@ -84,18 +87,20 @@ def test_profiler_restores_previous_profiler_after_failure() -> None:
     assert sys.getprofile() is previous
 
 
-def test_profiler_does_not_count_coroutine_resumption_as_another_call() -> None:
+@pytest.mark.parametrize("threads", (False, True))
+def test_profiler_does_not_count_coroutine_resumption_as_another_call(threads: bool) -> None:
     async def suspended() -> None:
         await asyncio.sleep(0)
         await asyncio.sleep(0)
 
-    with profile_python(Path(__file__).parent) as profiler:
+    with profile_python(Path(__file__).parent, threads=threads) as profiler:
         asyncio.run(suspended())
 
     assert len(_events_named(profiler, "suspended")) == 1
 
 
-def test_profiler_preserves_parent_across_coroutine_suspension() -> None:
+@pytest.mark.parametrize("threads", (False, True))
+def test_profiler_preserves_parent_across_coroutine_suspension(threads: bool) -> None:
     def called() -> None:
         return None
 
@@ -103,7 +108,7 @@ def test_profiler_preserves_parent_across_coroutine_suspension() -> None:
         await asyncio.sleep(0)
         called()
 
-    with profile_python(Path(__file__).parent) as profiler:
+    with profile_python(Path(__file__).parent, threads=threads) as profiler:
         asyncio.run(suspended())
 
     suspended_event: Final = _events_named(profiler, "suspended")[0]
@@ -124,6 +129,96 @@ def test_profiler_captures_worker_threads_when_enabled() -> None:
     assert called_event.parent_id is None
 
 
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="existing worker capture requires sys.monitoring")
+@pytest.mark.parametrize("prewarm", (False, True))
+def test_profiler_captures_reused_workers_without_leaking_between_sessions(prewarm: bool) -> None:
+    def called() -> None:
+        return None
+
+    with ThreadPoolExecutor(max_workers=1) as executor:
+        if prewarm:
+            executor.submit(called).result(timeout=5)
+        with profile_python(Path(__file__).parent, threads=True) as first:
+            executor.submit(called).result(timeout=5)
+        executor.submit(called).result(timeout=5)
+        with profile_python(Path(__file__).parent, threads=True) as second:
+            executor.submit(called).result(timeout=5)
+        executor.submit(called).result(timeout=5)
+
+    assert len(_events_named(first, "called")) == 1
+    assert len(_events_named(second, "called")) == 1
+
+
+def test_profiler_restores_main_and_worker_hooks_after_failure() -> None:
+    previous: Final = sys.getprofile()
+    previous_thread: Final = threading.getprofile()
+
+    with ThreadPoolExecutor(max_workers=1) as executor:
+        worker_previous: Final = executor.submit(sys.getprofile).result(timeout=5)
+        with pytest.raises(RuntimeError, match="stop"):
+            with profile_python(Path(__file__).parent, threads=True):
+                raise RuntimeError("stop")
+        assert executor.submit(sys.getprofile).result(timeout=5) is worker_previous
+
+    assert sys.getprofile() is previous
+    assert threading.getprofile() is previous_thread
+
+
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="existing worker capture requires sys.monitoring")
+def test_function_usage_profiler_captures_reused_workers() -> None:
+    def selected() -> None:
+        return None
+
+    function: Final = f"{Path(__file__).name}:{selected.__code__.co_firstlineno} {selected.__qualname__}"
+    with ThreadPoolExecutor(max_workers=1) as executor:
+        executor.submit(selected).result(timeout=5)
+        with profile_python_function_usage(Path(__file__).parent, frozenset((function,)), threads=True) as profiler:
+            executor.submit(selected).result(timeout=5)
+
+    assert profiler.called == {function}
+
+
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="independent thread hooks require sys.monitoring")
+def test_threaded_profiler_preserves_custom_worker_hook_and_releases_monitoring_slot() -> None:
+    def worker_hook(_frame: FrameType, _event: str, _arg: object) -> None:
+        return None
+
+    def fail_with_profile(executor: ThreadPoolExecutor) -> None:
+        with profile_python(Path(__file__).parent, threads=True):
+            assert executor.submit(sys.getprofile).result(timeout=5) is worker_hook
+            raise RuntimeError("stop")
+
+    tools_before: Final = tuple(sys.monitoring.get_tool(slot) for slot in range(6))
+    with ThreadPoolExecutor(max_workers=1, initializer=lambda: sys.setprofile(worker_hook)) as executor:
+        assert executor.submit(sys.getprofile).result(timeout=5) is worker_hook
+        with pytest.raises(RuntimeError, match="stop"):
+            fail_with_profile(executor)
+        assert executor.submit(sys.getprofile).result(timeout=5) is worker_hook
+
+    assert tuple(sys.monitoring.get_tool(slot) for slot in range(6)) == tools_before
+
+
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="existing worker capture requires sys.monitoring")
+def test_threaded_profiler_keeps_concurrent_event_ids_and_parent_links() -> None:
+    def child() -> None:
+        return None
+
+    def parent() -> None:
+        child()
+
+    with ThreadPoolExecutor(max_workers=4) as executor:
+        with profile_python(Path(__file__).parent, threads=True) as profiler:
+            futures: Final = tuple(executor.submit(parent) for _ in range(200))
+            for future in futures:
+                future.result(timeout=5)
+
+    parent_ids: Final = frozenset(event.id for event in _events_named(profiler, "parent"))
+    children: Final = _events_named(profiler, "child")
+    assert len(parent_ids) == len(children) == 200
+    assert frozenset(event.parent_id for event in children) == parent_ids
+    assert tuple(event.id for event in profiler.events) == tuple(range(len(profiler.events)))
+
+
 def test_function_usage_profiler_records_only_selected_functions() -> None:
     def selected() -> None:
         return None

tests/rust-python-harness/shared/tracing/test_steps.py

@@ -40,6 +40,23 @@ def test_python_projection_collapses_unmapped_parents_and_counts_noise() -> None
     ]
 
 
+@pytest.mark.parametrize("engine", ("python", "rust"))
+def test_projection_without_mappings_keeps_every_call_and_parent(engine: Engine) -> None:
+    events: Final = (
+        event(0, "module.py:1 entry"),
+        event(1, "module.py:2 internal_helper", 0),
+        event(2, "module.py:3 nested", 1),
+        event(3, "module.py:2 internal_helper", 0),
+    )
+
+    projection: Final = pipeline_projection(engine, events)
+
+    assert projection.unmatched == 0
+    assert tuple((step.id, step.parent_id, step.span, step.raw) for step in projection.steps) == tuple(
+        (item.id, item.parent_id, item.function, item.raw) for item in events
+    )
+
+
 def test_rust_projection_keeps_unknown_spans() -> None:
     projection: Final = pipeline_projection("rust", (event(0, "route"), event(1, "new_span", 0)), MAPPINGS)
     assert [(step.span, step.parent_id) for step in projection.steps] == [("route", None), ("new_span", 0)]
@@ -146,9 +163,7 @@ def test_trace_diff_allows_reordered_concurrent_children() -> None:
 def test_trace_diff_prunes_declared_engine_only_nodes_but_requires_them() -> None:
     mappings: Final = (MAPPINGS[0], mapping(rust_span="rust_prepare"))
     python: Final = pipeline_projection("python", (event(0, "module.py:1 entry"),), mappings).steps
-    rust: Final = pipeline_projection(
-        "rust", (event(0, "route"), event(1, "rust_prepare", 0)), mappings
-    ).steps
+    rust: Final = pipeline_projection("rust", (event(0, "route"), event(1, "rust_prepare", 0)), mappings).steps
     assert trace_diff(python, rust, mappings).matches
     assert trace_diff(python, rust[:1], mappings).missing_mappings == ("rust_prepare",)
 

tests/rust-python-harness/strategies/e2e_parity/sdk/ocr/fixtures/reducto.py

@@ -264,9 +264,7 @@ def _formatting_strategy() -> SearchStrategy[ReductoFormatting]:
         ),
         st.sampled_from((False, True)).map(lambda value: {"add_page_markers": value}),
         st.sampled_from((False, True)).map(lambda value: {"merge_tables": value}),
-        st.sampled_from(REDUCTO_FORMATTING_INCLUDE_GROUPS)
-        .map(list)
-        .map(lambda value: {"include": value}),
+        st.sampled_from(REDUCTO_FORMATTING_INCLUDE_GROUPS).map(list).map(lambda value: {"include": value}),
     )
     return values.map(ReductoFormatting.model_validate)
 

tests/rust-python-harness/strategies/e2e_parity/sdk/ocr/test_sdk_parity.py

@@ -124,10 +124,7 @@ class RecordingCallback(CustomLogger):
         if isinstance(value, Mapping):
             if any(not isinstance(map_key, str) for map_key in value):
                 raise TypeError("callback kwarg mappings must use string keys")
-            return {
-                map_key: self._normalized_kwargs(map_value, map_key)
-                for map_key, map_value in value.items()
-            }
+            return {map_key: self._normalized_kwargs(map_value, map_key) for map_key, map_value in value.items()}
         if isinstance(value, (list, tuple)):
             return [self._normalized_kwargs(item) for item in value]
         raise TypeError(f"unsupported callback kwarg type: {type(value)}")

tests/rust-python-harness/strategies/trace_parity/AGENTS.md

@@ -1 +1 @@
-Maps Python profiler frames onto feature-gated Rust span names via an explicit per-case mapping (Rust span name is the identity) and compares steps, order, and nesting of both live traces against a replayed provider response.
+Prints every collected Python call under litellm/ and every feature-gated Rust span from live traces against replayed HTTP responses. The two traces are independent and are not compared. API-key and Vertex credentials scenarios exercise separate authentication paths; credentials scenarios replay the token exchange locally.

tests/rust-python-harness/strategies/trace_parity/__init__.py

@@ -7,6 +7,7 @@ from ...shared.reporting.strategy import (
     ModuleCaseSpec,
     NotImplementedCaseSpec,
     RunnerArgumentDefinition,
+    RunnerOptionDefinition,
     StrategyDefinition,
 )
 from .reporting import render_trace_results
@@ -26,13 +27,17 @@ CASES: Final[tuple[CaseDefinition, ...]] = (
         ModuleCaseSpec(
             coverage=Coverage.PARTIAL,
             module="tests.rust-python-harness.strategies.trace_parity.sdk.messages.case",
-            note="Async only until anthropic_messages_handler supports sync calls.",
+            note="Success paths are async; sync tracing captures the currently unsupported behavior.",
         ),
         surface="sdk",
     ),
     CaseDefinition(
         "responses",
-        NotImplementedCaseSpec(reason="No Responses trace-parity case is registered."),
+        ModuleCaseSpec(
+            coverage=Coverage.PARTIAL,
+            module="tests.rust-python-harness.strategies.trace_parity.sdk.responses.case",
+            note="Core create paths: native, streaming, provider error, Azure override, and chat bridge.",
+        ),
         surface="sdk",
     ),
     CaseDefinition(
@@ -70,13 +75,17 @@ CASES: Final[tuple[CaseDefinition, ...]] = (
         ModuleCaseSpec(
             coverage=Coverage.PARTIAL,
             module="tests.rust-python-harness.strategies.trace_parity.gateway.messages.case",
-            note="Non-streaming success paths only.",
+            note="Anthropic/Azure provider routes plus a fully consumed downstream streaming path.",
         ),
         surface="gateway",
     ),
     CaseDefinition(
         "responses",
-        NotImplementedCaseSpec(reason="No gateway Responses trace-parity case is registered."),
+        ModuleCaseSpec(
+            coverage=Coverage.PARTIAL,
+            module="tests.rust-python-harness.strategies.trace_parity.gateway.responses.case",
+            note="Native OpenAI non-streaming and fully consumed downstream streaming paths.",
+        ),
         surface="gateway",
     ),
     CaseDefinition(
@@ -86,7 +95,11 @@ CASES: Final[tuple[CaseDefinition, ...]] = (
     ),
     CaseDefinition(
         "chat_completions",
-        NotImplementedCaseSpec(reason="No gateway chat trace-parity case is registered."),
+        ModuleCaseSpec(
+            coverage=Coverage.PARTIAL,
+            module="tests.rust-python-harness.strategies.trace_parity.gateway.chat_completions.case",
+            note="Anthropic non-streaming and fully consumed downstream streaming paths.",
+        ),
         surface="gateway",
     ),
     CaseDefinition(
@@ -99,8 +112,8 @@ CASES: Final[tuple[CaseDefinition, ...]] = (
 STRATEGY: Final = StrategyDefinition(
     id="trace_parity",
     order=20,
-    label="Trace parity",
-    description="Compare pipeline steps, order, and nesting between Python profiler frames and Rust spans via an explicit mapping.",
+    label="Traces",
+    description="Print Python profiler frames and Rust spans for representative pipeline scenarios.",
     directory=Path(__file__).parent,
     runnable_spec=ModuleCaseSpec,
     cases=CASES,
@@ -112,4 +125,11 @@ STRATEGY: Final = StrategyDefinition(
         metavar="NAME",
         help="run only this named trace scenario; repeat to select more than one",
     ),
+    runner_options=(
+        RunnerOptionDefinition(
+            option="--engine",
+            choices=("python", "rust"),
+            help="show only this engine's trace; omit to print both engines",
+        ),
+    ),
 )

tests/rust-python-harness/strategies/trace_parity/fixtures.py

@@ -0,0 +1,177 @@
+from __future__ import annotations
+
+import base64
+import binascii
+import json
+import struct
+from collections.abc import Iterable, Mapping
+from typing import Final
+
+from ...shared.parity.recorded_http import (
+    HttpHeader,
+    RecordedHttpResponse,
+    RecordedHttpStreamResponse,
+    RecordedStreamChunk,
+)
+
+JSON_HEADERS: Final = (HttpHeader(name="content-type", value="application/json"),)
+SSE_HEADERS: Final = (HttpHeader(name="content-type", value="text/event-stream"),)
+AWS_EVENT_STREAM_HEADERS: Final = (HttpHeader(name="content-type", value="application/vnd.amazon.eventstream"),)
+
+
+def json_response(body: Mapping[str, object] | bytes, *, status: int = 200) -> RecordedHttpResponse:
+    encoded: Final = body if isinstance(body, bytes) else json.dumps(body).encode()
+    return RecordedHttpResponse.from_bytes(status, JSON_HEADERS, encoded)
+
+
+def sse_event(event: str, payload: Mapping[str, object]) -> bytes:
+    return f"event: {event}\ndata: {json.dumps(payload, separators=(',', ':'))}\n\n".encode()
+
+
+def sse_response(events: Iterable[tuple[str, Mapping[str, object]]]) -> RecordedHttpStreamResponse:
+    return RecordedHttpStreamResponse(
+        kind="http_stream",
+        status_code=200,
+        headers=SSE_HEADERS,
+        chunks=tuple(RecordedStreamChunk.from_bytes(sse_event(event, payload)) for event, payload in events),
+    )
+
+
+def _aws_string_header(name: str, value: str) -> bytes:
+    name_bytes: Final = name.encode()
+    value_bytes: Final = value.encode()
+    return (
+        struct.pack("!B", len(name_bytes))
+        + name_bytes
+        + struct.pack("!B", 7)
+        + struct.pack("!H", len(value_bytes))
+        + value_bytes
+    )
+
+
+def aws_event_stream_frame(payload: Mapping[str, object]) -> bytes:
+    event_payload: Final = json.dumps(
+        {"bytes": base64.b64encode(json.dumps(payload, separators=(",", ":")).encode()).decode()},
+        separators=(",", ":"),
+    ).encode()
+    headers: Final = (
+        _aws_string_header(":event-type", "chunk")
+        + _aws_string_header(":content-type", "application/json")
+        + _aws_string_header(":message-type", "event")
+    )
+    total_length: Final = 12 + len(headers) + len(event_payload) + 4
+    prelude: Final = struct.pack("!II", total_length, len(headers))
+    prelude_crc: Final = binascii.crc32(prelude) & 0xFFFFFFFF
+    prelude_crc_bytes: Final = struct.pack("!I", prelude_crc)
+    message_crc: Final = binascii.crc32(prelude_crc_bytes + headers + event_payload, prelude_crc) & 0xFFFFFFFF
+    return prelude + prelude_crc_bytes + headers + event_payload + struct.pack("!I", message_crc)
+
+
+def aws_event_stream_response(
+    events: Iterable[Mapping[str, object]], *, corrupt_last_frame: bool = False
+) -> RecordedHttpStreamResponse:
+    frames: Final = tuple(aws_event_stream_frame(event) for event in events)
+    body: Final = (
+        b"".join((*frames[:-1], frames[-1][:-1] + bytes((frames[-1][-1] ^ 0xFF,))))
+        if corrupt_last_frame
+        else b"".join(frames)
+    )
+    return RecordedHttpStreamResponse(
+        kind="http_stream",
+        status_code=200,
+        headers=AWS_EVENT_STREAM_HEADERS,
+        chunks=(RecordedStreamChunk.from_bytes(body),),
+    )
+
+
+def anthropic_response_body(*, model: str = "claude-sonnet-5") -> dict[str, object]:
+    return {
+        "id": "msg_trace",
+        "type": "message",
+        "role": "assistant",
+        "model": model,
+        "content": [{"type": "text", "text": "hello"}],
+        "stop_reason": "end_turn",
+        "stop_sequence": None,
+        "usage": {"input_tokens": 2, "output_tokens": 3},
+    }
+
+
+def anthropic_stream_events(*, model: str = "claude-sonnet-5") -> tuple[tuple[str, Mapping[str, object]], ...]:
+    return (
+        (
+            "message_start",
+            {
+                "type": "message_start",
+                "message": {
+                    "id": "msg_trace",
+                    "type": "message",
+                    "role": "assistant",
+                    "model": model,
+                    "content": [],
+                    "stop_reason": None,
+                    "stop_sequence": None,
+                    "usage": {"input_tokens": 2, "output_tokens": 0},
+                },
+            },
+        ),
+        (
+            "content_block_start",
+            {"type": "content_block_start", "index": 0, "content_block": {"type": "text", "text": ""}},
+        ),
+        (
+            "content_block_delta",
+            {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": "hello"}},
+        ),
+        ("content_block_stop", {"type": "content_block_stop", "index": 0}),
+        (
+            "message_delta",
+            {
+                "type": "message_delta",
+                "delta": {"stop_reason": "end_turn", "stop_sequence": None},
+                "usage": {"output_tokens": 1},
+            },
+        ),
+        ("message_stop", {"type": "message_stop"}),
+    )
+
+
+def responses_body(*, model: str = "gpt-5", status: str = "completed") -> dict[str, object]:
+    return {
+        "id": "resp_trace",
+        "object": "response",
+        "created_at": 1_750_000_000,
+        "status": status,
+        "model": model,
+        "output": [
+            {
+                "type": "message",
+                "id": "msg_trace",
+                "status": "completed",
+                "role": "assistant",
+                "content": [{"type": "output_text", "text": "hello", "annotations": []}],
+            }
+        ],
+        "usage": {"input_tokens": 2, "output_tokens": 3, "total_tokens": 5},
+    }
+
+
+def responses_stream_events(*, model: str = "gpt-5") -> tuple[tuple[str, Mapping[str, object]], ...]:
+    response: Final = responses_body(model=model)
+    return (
+        (
+            "response.created",
+            {"type": "response.created", "response": {**response, "status": "in_progress", "output": []}},
+        ),
+        (
+            "response.output_text.delta",
+            {
+                "type": "response.output_text.delta",
+                "item_id": "msg_trace",
+                "output_index": 0,
+                "content_index": 0,
+                "delta": "hello",
+            },
+        ),
+        ("response.completed", {"type": "response.completed", "response": response}),
+    )

tests/rust-python-harness/strategies/trace_parity/gateway/chat_completions/case.py

@@ -0,0 +1,63 @@
+from __future__ import annotations
+
+from typing import Final
+
+from .....shared.tracing.steps import Engine, mapping
+from ...fixtures import anthropic_response_body, anthropic_stream_events, json_response, sse_response
+from ...models import GatewayRouteSpec, RouteFixture, TraceScenario, TraceSuite
+
+MAPPINGS: Final = (
+    mapping(span="python_chat_gateway_route", python_frame=r"proxy_server\.py:\d+ chat_completion$"),
+    mapping(span="python_gateway_service", python_frame=r"ProxyBaseLLMRequestProcessing\.base_process_llm_request$"),
+    mapping(span="python_chat_entrypoint", python_frame=r"main\.py:\d+ a?completion$"),
+    mapping(span="python_provider_config", python_frame=r"ProviderConfigManager\.get_provider_chat_config$"),
+    mapping(rust_span="validate_environment", python_frame=r"(?<!_)validate_environment$"),
+    mapping(rust_span="transform_request", python_frame=r"AnthropicConfig\.transform_request$"),
+    mapping(span="python_logging_pre_call", python_frame=r"Logging\.pre_call$"),
+    mapping(rust_span="http_request", python_frame=r"AsyncHTTPHandler\.post$|HTTPHandler\.post$"),
+    mapping(rust_span="transform_response", python_frame=r"AnthropicConfig\.transform_response$"),
+    mapping(span="python_success_callback", python_frame=r"Logging\.async_success_handler$|Logging\.success_handler$"),
+)
+
+STREAM_MAPPINGS: Final = (
+    mapping(span="python_stream_wrapper", python_frame=r"CustomStreamWrapper\.__init__$"),
+    mapping(span="python_stream_next", python_frame=r"CustomStreamWrapper\.__anext__$"),
+    mapping(span="python_stream_chunk", python_frame=r"CustomStreamWrapper\.chunk_creator$"),
+    mapping(span="python_downstream_stream", python_frame=r"DataGenerator\.__anext__$|async_data_generator$"),
+)
+
+
+def _fixture(_engine: Engine, _base_url: str) -> RouteFixture:
+    return RouteFixture(
+        kwargs={
+            "model_alias": "trace-model",
+            "provider_model": "anthropic/claude-sonnet-5",
+            "body": {
+                "model": "trace-model",
+                "messages": [{"role": "user", "content": "hello"}],
+                "max_tokens": 16,
+            },
+        },
+        provider_responses=(json_response(anthropic_response_body()),),
+    )
+
+
+def _stream_fixture(engine: Engine, base_url: str) -> RouteFixture:
+    fixture: Final = _fixture(engine, base_url)
+    return fixture.with_body(stream=True).derive(
+        provider_responses=(sse_response(anthropic_stream_events()),),
+    )
+
+
+TRACE_SUITE: Final = TraceSuite(
+    route=GatewayRouteSpec("chat_completions", rust_supported=False),
+    scenarios=(
+        TraceScenario(name="async-anthropic", fixture=_fixture, mappings=MAPPINGS, asynchronous=True),
+        TraceScenario(
+            name="async-anthropic-downstream-stream",
+            fixture=_stream_fixture,
+            mappings=(*MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=True,
+        ),
+    ),
+)

tests/rust-python-harness/strategies/trace_parity/gateway/execution.py

@@ -13,8 +13,8 @@ from ....shared.parity.replay import replay_server
 from ....shared.tracing.native import TraceResponsePayload, native_trace_events
 from ....shared.tracing.profiler import FunctionTraceEvent, profile_python
 from ....shared.tracing.steps import Engine, PipelineProjection, pipeline_projection
-from ..models import GatewayRouteSpec, RouteFixture, TraceExecutionFailure, TraceMode, TraceScenario
-from ..reporting import TraceComparisonArtifact
+from ..models import GatewayRouteSpec, RouteFixture, TraceEngine, TraceExecutionFailure, TraceScenario
+from ..reporting import TraceArtifact
 
 
 class _GatewayResponsePayload(BaseModel):
@@ -28,7 +28,14 @@ class _GatewayClient(Protocol):
     def post(self, url: str, *, json: object, headers: dict[str, str]) -> httpx.Response: ...
 
 
-def _collect_python(fixture: RouteFixture) -> tuple[FunctionTraceEvent, ...]:
+_ROUTE_PATHS: Final = {
+    "messages": "/v1/messages",
+    "chat_completions": "/v1/chat/completions",
+    "responses": "/v1/responses",
+}
+
+
+def _collect_python(fixture: RouteFixture, route: GatewayRouteSpec) -> tuple[FunctionTraceEvent, ...]:
     from fastapi.testclient import TestClient
 
     import litellm
@@ -61,7 +68,7 @@ def _collect_python(fixture: RouteFixture) -> tuple[FunctionTraceEvent, ...]:
         with profile_python(Path(litellm.__file__).parent, threads=True) as profiler:
             client: Final = cast(_GatewayClient, TestClient(proxy_server.app))
             response: Final = client.post(
-                "/v1/messages",
+                _ROUTE_PATHS[route.route],
                 json=fixture.kwargs["body"],
                 headers={"authorization": "Bearer trace-key"},
             )
@@ -76,9 +83,10 @@ def _collect_python(fixture: RouteFixture) -> tuple[FunctionTraceEvent, ...]:
             proxy_server.app.dependency_overrides[user_api_key_auth] = old_override
 
 
-def _collect_rust(fixture: RouteFixture) -> tuple[FunctionTraceEvent, ...]:
+def _collect_rust(fixture: RouteFixture, route: GatewayRouteSpec) -> tuple[FunctionTraceEvent, ...]:
     payload: Final = json.dumps(
         {
+            "path": _ROUTE_PATHS[route.route],
             "model_alias": fixture.kwargs["model_alias"],
             "provider_model": fixture.kwargs["provider_model"],
             "api_base": fixture.kwargs["api_base"],
@@ -130,7 +138,9 @@ def _gateway_trace_binary() -> Path:
     return rust_root / "target" / "debug" / "trace-parity-gateway"
 
 
-def _collect(scenario: TraceScenario, engine: Engine) -> tuple[FunctionTraceEvent, ...] | TraceExecutionFailure:
+def _collect(
+    route: GatewayRouteSpec, scenario: TraceScenario, engine: Engine
+) -> tuple[FunctionTraceEvent, ...] | TraceExecutionFailure:
     try:
         with replay_server() as provider:
             base_fixture: Final = scenario.fixture(engine, provider.url)
@@ -140,7 +150,7 @@ def _collect(scenario: TraceScenario, engine: Engine) -> tuple[FunctionTraceEven
             )
             for response in fixture.provider_responses:
                 provider.enqueue_response(response)
-            events: Final = _collect_python(fixture) if engine == "python" else _collect_rust(fixture)
+            events: Final = _collect_python(fixture, route) if engine == "python" else _collect_rust(fixture, route)
             provider.take_requests(len(fixture.provider_responses))
         return events
     except Exception as error:
@@ -150,40 +160,38 @@ def _collect(scenario: TraceScenario, engine: Engine) -> tuple[FunctionTraceEven
 def _projections(
     python_events: tuple[FunctionTraceEvent, ...],
     rust_events: tuple[FunctionTraceEvent, ...],
-    scenario: TraceScenario,
-    mode: TraceMode,
 ) -> tuple[PipelineProjection, PipelineProjection, str | None]:
-    mappings: Final = scenario.mappings_for(mode)
     try:
         return (
-            pipeline_projection("python", python_events, mappings),
-            pipeline_projection("rust", rust_events, mappings),
+            pipeline_projection("python", python_events),
+            pipeline_projection("rust", rust_events),
             None,
         )
     except ValueError as error:
         return PipelineProjection(), PipelineProjection(), f"harness: {error}"
 
 
-def execute_gateway_trace(route: GatewayRouteSpec, scenario: TraceScenario, mode: TraceMode) -> TraceComparisonArtifact:
-    mappings: Final = scenario.mappings_for(mode)
-    python_trace: Final = _collect(scenario, "python")
-    rust_trace: Final = _collect(scenario, "rust")
+def execute_gateway_trace(
+    route: GatewayRouteSpec,
+    scenario: TraceScenario,
+    engine: TraceEngine = "both",
+) -> TraceArtifact:
+    effective_engine: Final[TraceEngine] = "python" if engine == "both" and not route.rust_supported else engine
+    python_trace: Final = _collect(route, scenario, "python") if effective_engine != "rust" else ()
+    rust_trace: Final = _collect(route, scenario, "rust") if effective_engine != "python" else ()
     collection_python_error: Final = None if isinstance(python_trace, tuple) else f"python: {python_trace.message}"
     rust_error: Final = None if isinstance(rust_trace, tuple) else f"rust: {rust_trace.message}"
     python_events: Final = python_trace if isinstance(python_trace, tuple) else ()
     rust_events: Final = rust_trace if isinstance(rust_trace, tuple) else ()
-    python, rust, projection_error = _projections(python_events, rust_events, scenario, mode)
+    python, rust, projection_error = _projections(python_events, rust_events)
     python_error: Final = projection_error or collection_python_error
-    return TraceComparisonArtifact.from_traces(
+    return TraceArtifact.from_traces(
+        engine=effective_engine,
         surface="gateway",
         sdk_function=route.route,
         scenario=scenario.name,
-        mode=mode,
-        mappings=mappings,
-        contract=scenario.contract,
         python=python.steps,
         rust=rust.steps,
-        python_unmatched=python.unmatched,
         python_error=python_error,
         rust_error=rust_error,
     )

tests/rust-python-harness/strategies/trace_parity/gateway/messages/case.py

@@ -1,10 +1,9 @@
 from __future__ import annotations
 
-import json
 from typing import Final
 
-from .....shared.parity.recorded_http import HttpHeader, RecordedHttpResponse
 from .....shared.tracing.steps import Engine, mapping
+from ...fixtures import anthropic_response_body, anthropic_stream_events, json_response, sse_response
 from ...models import GatewayRouteSpec, RouteFixture, TraceScenario, TraceSuite
 
 
@@ -49,24 +48,7 @@ def _fixture(_engine: Engine, provider: str) -> RouteFixture:
                 "max_tokens": 16,
             },
         },
-        provider_responses=(
-            RecordedHttpResponse.from_bytes(
-                200,
-                (HttpHeader(name="content-type", value="application/json"),),
-                json.dumps(
-                    {
-                        "id": "msg_trace",
-                        "type": "message",
-                        "role": "assistant",
-                        "model": "claude-sonnet-5",
-                        "content": [{"type": "text", "text": "hello"}],
-                        "stop_reason": "end_turn",
-                        "stop_sequence": None,
-                        "usage": {"input_tokens": 2, "output_tokens": 3},
-                    }
-                ).encode(),
-            ),
-        ),
+        provider_responses=(json_response(anthropic_response_body()),),
     )
 
 
@@ -78,6 +60,13 @@ def _azure_fixture(engine: Engine, _base_url: str) -> RouteFixture:
     return _fixture(engine, "azure_ai")
 
 
+def _stream_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _anthropic_fixture(engine, _base_url)
+    return fixture.with_body(stream=True).derive(
+        provider_responses=(sse_response(anthropic_stream_events()),),
+    )
+
+
 ANTHROPIC_MAPPINGS: Final = (
     *GATEWAY_MAPPINGS,
     mapping(
@@ -100,7 +89,22 @@ AZURE_MAPPINGS: Final = (
 TRACE_SUITE: Final = TraceSuite(
     route=GatewayRouteSpec("messages"),
     scenarios=(
-        TraceScenario(name="anthropic", fixture=_anthropic_fixture, mappings=ANTHROPIC_MAPPINGS, modes=("async",)),
-        TraceScenario(name="azure-ai", fixture=_azure_fixture, mappings=AZURE_MAPPINGS, modes=("async",)),
+        TraceScenario(
+            name="async-anthropic", fixture=_anthropic_fixture, mappings=ANTHROPIC_MAPPINGS, asynchronous=True
+        ),
+        TraceScenario(name="async-azure-ai", fixture=_azure_fixture, mappings=AZURE_MAPPINGS, asynchronous=True),
+        TraceScenario(
+            name="async-anthropic-downstream-stream",
+            fixture=_stream_fixture,
+            mappings=(
+                *ANTHROPIC_MAPPINGS,
+                mapping(span="python_upstream_stream", python_frame=r"AnthropicMessagesStreamingResponse\.__anext__$"),
+                mapping(
+                    span="python_downstream_stream", python_frame=r"DataGenerator\.__anext__$|async_data_generator$"
+                ),
+                mapping(span="python_stream_callback", python_frame=r"Logging\.async_success_handler$"),
+            ),
+            asynchronous=True,
+        ),
     ),
 )

tests/rust-python-harness/strategies/trace_parity/gateway/responses/case.py

@@ -0,0 +1,62 @@
+from __future__ import annotations
+
+from typing import Final
+
+from .....shared.tracing.steps import Engine, mapping
+from ...fixtures import json_response, responses_body, responses_stream_events, sse_response
+from ...models import GatewayRouteSpec, RouteFixture, TraceScenario, TraceSuite
+
+MAPPINGS: Final = (
+    mapping(
+        span="python_responses_gateway_route", python_frame=r"response_api_endpoints/endpoints\.py:\d+ responses_api$"
+    ),
+    mapping(span="python_gateway_service", python_frame=r"ProxyBaseLLMRequestProcessing\.base_process_llm_request$"),
+    mapping(span="python_responses", python_frame=r"responses/main\.py:\d+ a?responses$"),
+    mapping(span="python_provider_config", python_frame=r"ProviderConfigManager\.get_provider_responses_api_config$"),
+    mapping(rust_span="validate_environment", python_frame=r"OpenAIResponsesAPIConfig\.validate_environment$"),
+    mapping(rust_span="complete_url", python_frame=r"OpenAIResponsesAPIConfig\.get_complete_url$"),
+    mapping(rust_span="transform_request", python_frame=r"OpenAIResponsesAPIConfig\.transform_responses_api_request$"),
+    mapping(span="python_logging_pre_call", python_frame=r"Logging\.pre_call$"),
+    mapping(rust_span="http_request", python_frame=r"AsyncHTTPHandler\.post$|HTTPHandler\.post$"),
+    mapping(rust_span="transform_response", python_frame=r"OpenAIResponsesAPIConfig\.transform_response_api_response$"),
+    mapping(span="python_success_callback", python_frame=r"Logging\.async_success_handler$|Logging\.success_handler$"),
+)
+
+STREAM_MAPPINGS: Final = (
+    mapping(span="python_stream_iterator", python_frame=r"ResponsesAPIStreamingIterator\.__init__$"),
+    mapping(span="python_stream_next", python_frame=r"ResponsesAPIStreamingIterator\.__anext__$"),
+    mapping(span="python_stream_transform", python_frame=r"OpenAIResponsesAPIConfig\.transform_streaming_response$"),
+    mapping(span="python_downstream_stream", python_frame=r"DataGenerator\.__anext__$|async_data_generator$"),
+)
+
+
+def _fixture(_engine: Engine, _base_url: str) -> RouteFixture:
+    return RouteFixture(
+        kwargs={
+            "model_alias": "trace-model",
+            "provider_model": "openai/gpt-5",
+            "body": {"model": "trace-model", "input": "hello"},
+        },
+        provider_responses=(json_response(responses_body()),),
+    )
+
+
+def _stream_fixture(engine: Engine, base_url: str) -> RouteFixture:
+    fixture: Final = _fixture(engine, base_url)
+    return fixture.with_body(stream=True).derive(
+        provider_responses=(sse_response(responses_stream_events()),),
+    )
+
+
+TRACE_SUITE: Final = TraceSuite(
+    route=GatewayRouteSpec("responses", rust_supported=False),
+    scenarios=(
+        TraceScenario(name="async-openai", fixture=_fixture, mappings=MAPPINGS, asynchronous=True),
+        TraceScenario(
+            name="async-openai-downstream-stream",
+            fixture=_stream_fixture,
+            mappings=(*MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=True,
+        ),
+    ),
+)

tests/rust-python-harness/strategies/trace_parity/models.py

@@ -1,35 +1,61 @@
 from __future__ import annotations
 
-from collections.abc import Callable
+from collections.abc import Callable, Mapping
 from dataclasses import dataclass
-from typing import Final, Literal, TypeAlias
+from typing import Final, Literal, TypeAlias, cast
 
-from ...shared.parity.recorded_http import RecordedHttpResponse
+from ...shared.parity.recorded_http import RecordedResponse
 from ...shared.reporting.models import SdkFunction
-from ...shared.tracing.steps import Engine, TraceContract, TraceMapping
+from ...shared.tracing.steps import Engine, TraceMapping
 
-TraceMode = Literal["sync", "async"]
+TraceEngine = Literal["python", "rust", "both"]
 TraceFailureSource = Literal["python", "rust", "harness"]
 
 
 @dataclass(frozen=True, slots=True)
 class RouteFixture:
     kwargs: dict[str, object]
-    provider_responses: tuple[RecordedHttpResponse, ...]
+    provider_responses: tuple[RecordedResponse, ...]
     expected_failure: bool = False
+    consume_stream: bool = False
+    environment: tuple[tuple[str, str], ...] = ()
+
+    def derive(
+        self,
+        *,
+        kwargs: Mapping[str, object] | None = None,
+        provider_responses: tuple[RecordedResponse, ...] | None = None,
+        expected_failure: bool | None = None,
+        consume_stream: bool | None = None,
+    ) -> RouteFixture:
+        return RouteFixture(
+            kwargs={**self.kwargs, **(kwargs or {})},
+            provider_responses=self.provider_responses if provider_responses is None else provider_responses,
+            expected_failure=self.expected_failure if expected_failure is None else expected_failure,
+            consume_stream=self.consume_stream if consume_stream is None else consume_stream,
+            environment=self.environment,
+        )
+
+    def with_body(self, **updates: object) -> RouteFixture:
+        raw_body: Final = self.kwargs.get("body")
+        if not isinstance(raw_body, dict):
+            raise ValueError("route fixture does not contain an object body")
+        body: Final = cast(dict[str, object], raw_body)
+        return self.derive(kwargs={"body": {**body, **updates}})
 
 
 @dataclass(frozen=True, slots=True)
 class RouteSpec:
     route: SdkFunction
     python_entrypoints: tuple[str, str]
-    rust_entrypoints: tuple[str, str]
+    rust_entrypoints: tuple[str, str] | None
     fixture: Callable[[Engine, str], RouteFixture]
 
 
 @dataclass(frozen=True, slots=True)
 class GatewayRouteSpec:
     route: SdkFunction
+    rust_supported: bool = True
 
 
 TraceRouteSpec: TypeAlias = RouteSpec | GatewayRouteSpec
@@ -40,14 +66,7 @@ class TraceScenario:
     name: str
     fixture: Callable[[Engine, str], RouteFixture]
     mappings: tuple[TraceMapping, ...]
-    modes: tuple[TraceMode, ...] = ("sync", "async")
-    contract: TraceContract = TraceContract()
-    sync_mappings: tuple[TraceMapping, ...] | None = None
-    async_mappings: tuple[TraceMapping, ...] | None = None
-
-    def mappings_for(self, mode: TraceMode) -> tuple[TraceMapping, ...]:
-        selected: Final = self.async_mappings if mode == "async" else self.sync_mappings
-        return self.mappings if selected is None else selected
+    asynchronous: bool
 
 
 @dataclass(frozen=True, slots=True)

tests/rust-python-harness/strategies/trace_parity/reporting.py

@@ -1,31 +1,24 @@
 from __future__ import annotations
 
 import os
-import re
 import sys
 from collections.abc import Sequence
-from typing import Final, Literal
+from typing import Final
 
 from pydantic import BaseModel, ConfigDict, ValidationError
 
 from ...shared.reporting.models import SURFACES, CaseResult, RunStatus, SdkFunction, Surface
 from ...shared.reporting.rendering import ReportSection
 from ...shared.reporting.strategy import NotImplementedCaseSpec, SkippedCaseSpec
-from ...shared.tracing.steps import (
-    PipelineStep,
-    TraceContract,
-    TraceDiff,
-    TraceMapping,
-    trace_depths,
-    trace_diff,
-)
+from ...shared.tracing.steps import PipelineStep, trace_depths
+from .models import TraceEngine
 
-TRACE_COMPARISON_ARTIFACT: Final = "trace_comparison"
+TRACE_ARTIFACT: Final = "trace"
 TRACE_PARITY_HINT: Final = (
     "rebuild the native bridge with the trace-parity feature, e.g. `uvx maturin develop --features trace-parity`"
 )
 
-_COLORS: Final[dict[str, str]] = {"green": "32", "yellow": "33", "red": "31", "cyan": "36"}
+_COLORS: Final[dict[str, str]] = {"yellow": "33", "red": "31", "cyan": "36"}
 _RESET: Final = "\033[0m"
 
 
@@ -47,26 +40,15 @@ class TraceEventArtifact(BaseModel):
         return PipelineStep(self.id, self.parent_id, self.span, self.raw)
 
 
-class TraceMappingArtifact(BaseModel):
-    model_config = ConfigDict(frozen=True, extra="forbid")
-
-    span: str
-    python: str | None
-    rust: str | None
-
-
-class TraceComparisonArtifact(BaseModel):
+class TraceArtifact(BaseModel):
     model_config = ConfigDict(frozen=True, extra="forbid")
 
+    engine: TraceEngine = "both"
     surface: Surface
     sdk_function: SdkFunction
     scenario: str
-    mode: Literal["sync", "async"]
-    mappings: tuple[TraceMappingArtifact, ...]
     python: tuple[TraceEventArtifact, ...]
     rust: tuple[TraceEventArtifact, ...]
-    python_unmatched: int
-    unordered_children_of: frozenset[str]
     python_error: str | None = None
     rust_error: str | None = None
 
@@ -74,41 +56,27 @@ class TraceComparisonArtifact(BaseModel):
     def from_traces(
         cls,
         *,
+        engine: TraceEngine = "both",
         surface: Surface,
         sdk_function: SdkFunction,
         scenario: str,
-        mode: Literal["sync", "async"],
-        mappings: Sequence[TraceMapping],
-        contract: TraceContract,
         python: Sequence[PipelineStep],
         rust: Sequence[PipelineStep],
-        python_unmatched: int,
         python_error: str | None = None,
         rust_error: str | None = None,
-    ) -> TraceComparisonArtifact:
+    ) -> TraceArtifact:
         return cls(
+            engine=engine,
             surface=surface,
             sdk_function=sdk_function,
             scenario=scenario,
-            mode=mode,
-            mappings=tuple(
-                TraceMappingArtifact(
-                    span=item.span,
-                    python=item.python.pattern if item.python else None,
-                    rust=item.rust,
-                )
-                for item in mappings
-            ),
             python=tuple(
                 TraceEventArtifact(id=step.id, parent_id=step.parent_id, span=step.span, raw=step.raw)
                 for step in python
             ),
             rust=tuple(
-                TraceEventArtifact(id=step.id, parent_id=step.parent_id, span=step.span, raw=step.raw)
-                for step in rust
+                TraceEventArtifact(id=step.id, parent_id=step.parent_id, span=step.span, raw=step.raw) for step in rust
             ),
-            python_unmatched=python_unmatched,
-            unordered_children_of=contract.unordered_children_of,
             python_error=python_error,
             rust_error=rust_error,
         )
@@ -119,32 +87,9 @@ class TraceComparisonArtifact(BaseModel):
     def rust_steps(self) -> tuple[PipelineStep, ...]:
         return tuple(event.step() for event in self.rust)
 
-    def diff(self) -> TraceDiff:
-        return trace_diff(
-            self.python_steps(),
-            self.rust_steps(),
-            tuple(
-                TraceMapping(
-                    item.span,
-                    re.compile(item.python) if item.python is not None else None,
-                    item.rust,
-                )
-                for item in self.mappings
-            ),
-            TraceContract(self.unordered_children_of),
-        )
-
-    def exact_match(self) -> bool:
-        return self.diff().matches
-
     def has_errors(self) -> bool:
         return self.python_error is not None or self.rust_error is not None
 
-    def contract_matches(self) -> bool:
-        if self.has_errors():
-            return False
-        return self.diff().matches
-
 
 def _split_raw(raw: str) -> tuple[str, str]:
     location, separator, name = raw.partition(" ")
@@ -153,72 +98,28 @@ def _split_raw(raw: str) -> tuple[str, str]:
     return raw, ""
 
 
-def _python_line(index: int, step: PipelineStep, depth: int, exclusive: frozenset[str]) -> str:
+def _python_line(index: int, step: PipelineStep, depth: int) -> str:
     name: Final = _split_raw(step.raw)[0]
     location: Final = _split_raw(step.raw)[1]
     suffix: Final = f"  ({location})" if location else ""
-    marker: Final = "  [python only]" if step.span in exclusive else ""
-    return _paint(f"{index} {'  ' * depth}{name}{suffix}{marker}", "cyan")
+    return _paint(f"{index} {'  ' * depth}{name}{suffix}", "cyan")
 
 
-def _python_lines(steps: tuple[PipelineStep, ...], exclusive: frozenset[str]) -> str:
+def _python_lines(steps: tuple[PipelineStep, ...]) -> str:
     depths: Final = trace_depths(steps)
-    lines: Final = tuple(
-        _python_line(index, step, depths[step.id], exclusive) for index, step in enumerate(steps, start=1)
-    )
+    lines: Final = tuple(_python_line(index, step, depths[step.id]) for index, step in enumerate(steps, start=1))
     return f"{_paint('PYTHON', 'cyan')} ({len(steps)} steps)\n" + ("\n".join(lines) if lines else "(empty)")
 
 
-def _python_references(steps: tuple[PipelineStep, ...]) -> dict[tuple[str, int], str]:
-    references: dict[tuple[str, int], str] = {}
-    occurrences: dict[str, int] = {}
-    for index, step in enumerate(steps, start=1):
-        name = _split_raw(step.raw)[0]
-        occurrence = occurrences.get(step.span, 0) + 1
-        occurrences[step.span] = occurrence
-        references[(step.span, occurrence)] = f"{index} {name}"
-    return references
-
-
-def _rust_line(
-    step: PipelineStep,
-    depth: int,
-    occurrence: int,
-    references: dict[tuple[str, int], str],
-) -> str:
-    span: Final = _paint(step.span, "yellow")
-    key: Final = (step.span, occurrence)
-    reference: Final = (
-        _paint(references[key], "cyan") if key in references else _paint("[rust only]", "yellow")
-    )
-    suffix: Final = f"#{occurrence}" if occurrence > 1 else ""
-    return f"{'  ' * depth}{span}{suffix}  ->  {reference}"
-
-
-def _rust_lines(steps: tuple[PipelineStep, ...], references: dict[tuple[str, int], str]) -> str:
+def _rust_lines(steps: tuple[PipelineStep, ...]) -> str:
     depths: Final = trace_depths(steps)
-    occurrences: dict[str, int] = {}
-    lines: list[str] = []
-    for step in steps:
-        occurrence = occurrences.get(step.span, 0) + 1
-        occurrences[step.span] = occurrence
-        lines.append(_rust_line(step, depths[step.id], occurrence, references))
+    lines: Final = tuple(
+        _paint(f"{index} {'  ' * depths[step.id]}{step.span}", "yellow") for index, step in enumerate(steps, 1)
+    )
     return f"{_paint('RUST', 'yellow')} ({len(steps)} steps)\n" + ("\n".join(lines) if lines else "(empty)")
 
 
-def _state_text(state: str, *, good: bool) -> str:
-    return _paint(state, "green" if good else "red")
-
-
-def _contract_line(artifact: TraceComparisonArtifact) -> str:
-    matches: Final = artifact.contract_matches()
-    status: Final = _state_text("PASS" if matches else "FAIL", good=matches)
-    if artifact.python_error or artifact.rust_error:
-        return f"Contract: {status}"
-    return f"Contract: {status}"
-
-
-def _error_lines(artifact: TraceComparisonArtifact) -> tuple[str, ...]:
+def _error_lines(artifact: TraceArtifact) -> tuple[str, ...]:
     lines: list[str] = []
     for engine, error in (("Python", artifact.python_error), ("Rust", artifact.rust_error)):
         if error is None:
@@ -229,68 +130,20 @@ def _error_lines(artifact: TraceComparisonArtifact) -> tuple[str, ...]:
     return tuple(lines)
 
 
-def _unseen_mappings(
-    artifact: TraceComparisonArtifact,
-    python: tuple[PipelineStep, ...],
-    rust: tuple[PipelineStep, ...],
-) -> tuple[str, ...]:
-    return artifact.diff().missing_mappings
-
-
-def _comparison_status_lines(
-    artifact: TraceComparisonArtifact,
-    python: tuple[PipelineStep, ...],
-    rust: tuple[PipelineStep, ...],
-) -> tuple[str, ...]:
-    diff: Final = artifact.diff()
-    exact_match: Final = artifact.exact_match()
-    if artifact.has_errors():
-        return (*_error_lines(artifact), _contract_line(artifact))
-    unseen: Final = _unseen_mappings(artifact, python, rust)
-    unseen_line: Final[tuple[str, ...]] = (f"Unseen mappings: {', '.join(unseen)}",) if unseen else ()
-    drift_lines: Final[tuple[str, ...]] = (
-        (_state_text("Same steps, order, and nesting", good=True),)
-        if exact_match
-        else (
-            _paint(f"Python only: {', '.join(diff.python_only) or 'none'}", "cyan"),
-            _paint(f"Rust only: {', '.join(diff.rust_only) or 'none'}", "yellow"),
-            f"First difference: {diff.first_difference or 'none'}",
-            f"Python frames outside mapping: {artifact.python_unmatched}",
-        )
-    )
-    return (
-        f"Trace: {_state_text('MATCH' if exact_match else 'DRIFT', good=exact_match)}",
-        *drift_lines,
-        *unseen_line,
-        _contract_line(artifact),
-    )
-
-
-def _render_comparison(artifact: TraceComparisonArtifact) -> str:
-    python: Final = artifact.python_steps()
-    rust: Final = artifact.rust_steps()
-    diff: Final = artifact.diff()
-    python_exclusive: Final = frozenset(item.span for item in artifact.mappings if item.rust is None)
-    status_lines: Final = _comparison_status_lines(artifact, python, rust)
-    return "\n\n".join(
-        (
-            _python_lines(python, python_exclusive | frozenset(diff.python_only)),
-            _rust_lines(rust, _python_references(python)),
-            "\n".join(status_lines),
-        )
-    )
-
-
-def _mode(nodeid: str) -> str:
-    if "[" in nodeid:
-        return nodeid.rsplit("[", 1)[-1].removesuffix("]")
-    head, _, tail = nodeid.rpartition(":")
-    return tail if head else "unknown mode"
+def _render_trace(artifact: TraceArtifact) -> str:
+    traces: tuple[str, ...]
+    if artifact.engine == "python":
+        traces = (_python_lines(artifact.python_steps()),)
+    elif artifact.engine == "rust":
+        traces = (_rust_lines(artifact.rust_steps()),)
+    else:
+        traces = (_python_lines(artifact.python_steps()), _rust_lines(artifact.rust_steps()))
+    return "\n\n".join((*traces, *_error_lines(artifact)))
 
 
 def _scenario(nodeid: str) -> str:
     parts: Final = nodeid.split(":")
-    return parts[-2] if len(parts) >= 5 else "default"
+    return parts[-1] if len(parts) >= 4 else "default"
 
 
 def _unavailable(status: RunStatus) -> str:
@@ -299,20 +152,20 @@ def _unavailable(status: RunStatus) -> str:
 
 def _render_artifact(body: str) -> str:
     try:
-        artifact: Final = TraceComparisonArtifact.model_validate_json(body)
+        artifact: Final = TraceArtifact.model_validate_json(body)
     except ValidationError as error:
-        return f"Trace comparison artifact is invalid: {error}"
-    return _render_comparison(artifact)
+        return f"Trace artifact is invalid: {error}"
+    return _render_trace(artifact)
 
 
-def _mode_section(result: CaseResult, nodeid: str, status: RunStatus) -> str:
+def _scenario_section(result: CaseResult, nodeid: str, status: RunStatus) -> str:
     artifacts: Final = tuple(
-        artifact for artifact in result.artifacts.get(nodeid, ()) if artifact.kind == TRACE_COMPARISON_ARTIFACT
+        artifact for artifact in result.artifacts.get(nodeid, ()) if artifact.kind == TRACE_ARTIFACT
     )
     body: Final = (
         "\n\n".join(_render_artifact(artifact.body) for artifact in artifacts) if artifacts else _unavailable(status)
     )
-    label: Final = f"Scenario: {_scenario(nodeid)} / Mode: {_mode(nodeid)}"
+    label: Final = f"Scenario: {_scenario(nodeid)}"
     return f"{label}\n{'-' * len(label)}\n\n{body}"
 
 
@@ -321,7 +174,7 @@ def _case_block(result: CaseResult) -> str:
     outcomes: Final = tuple(result.outcomes.items()) or (
         (nodeid, RunStatus.NOT_RUN) for nodeid in sorted(result.collected)
     )
-    sections: Final = tuple(_mode_section(result, nodeid, status) for nodeid, status in outcomes)
+    sections: Final = tuple(_scenario_section(result, nodeid, status) for nodeid, status in outcomes)
     return "\n\n".join((f"{header}\n{'=' * len(header)}", *sections))
 
 
@@ -357,11 +210,11 @@ def _surface_section(surface: Surface, results: Sequence[CaseResult]) -> ReportS
         *((not_implemented,) if not_implemented else ()),
         *((skipped,) if skipped else ()),
     )
-    return ReportSection(f"{surface.upper()} trace comparisons", blocks or ("No runnable trace comparisons",))
+    return ReportSection(f"{surface.upper()} traces", blocks or ("No runnable traces",))
 
 
 def render_trace_results(results: Sequence[CaseResult]) -> tuple[ReportSection, ...]:
     sections: Final = tuple(
         section for surface in SURFACES if (section := _surface_section(surface, results)) is not None
     )
-    return sections or (ReportSection("Trace comparisons", ("No trace comparisons selected",)),)
+    return sections or (ReportSection("Traces", ("No traces selected",)),)

tests/rust-python-harness/strategies/trace_parity/runner.py

@@ -4,13 +4,20 @@ import importlib
 from collections.abc import Sequence
 from pathlib import Path
 from time import monotonic
-from typing import Final
+from typing import Final, cast
 
+from ...shared.native_build import ensure_trace_bridge
 from ...shared.reporting.models import CaseResult, HarnessCase, HarnessRun, ResultArtifact, RunStatus, Surface
 from ...shared.reporting.strategy import ModuleCaseSpec, UpdateCallback
-from ...shared.native_build import ensure_trace_bridge
-from .models import GatewayRouteSpec, RouteSpec, TraceExecutionFailure, TraceMode, TraceScenario, TraceSuite
-from .reporting import TRACE_COMPARISON_ARTIFACT, TraceComparisonArtifact
+from .models import (
+    GatewayRouteSpec,
+    RouteSpec,
+    TraceEngine,
+    TraceExecutionFailure,
+    TraceScenario,
+    TraceSuite,
+)
+from .reporting import TRACE_ARTIFACT, TraceArtifact
 from .sdk.execution import execute_trace
 
 
@@ -32,15 +39,13 @@ def validate_trace_suite(suite: TraceSuite, harness_case: HarnessCase) -> str |
     names: Final = tuple(scenario.name for scenario in suite.scenarios)
     if not names or len(names) != len(set(names)) or any(not name or ":" in name for name in names):
         return "scenario names must be non-empty, unique, and colon-free"
-    invalid_modes: Final = tuple(
+    invalid_names: Final = tuple(
         scenario.name
         for scenario in suite.scenarios
-        if not scenario.modes
-        or len(scenario.modes) != len(set(scenario.modes))
-        or any(mode not in {"sync", "async"} for mode in scenario.modes)
+        if not scenario.name.startswith("async-" if scenario.asynchronous else "sync-")
     )
-    if invalid_modes:
-        return f"scenarios must use non-empty, unique sync/async modes: {', '.join(invalid_modes)}"
+    if invalid_names:
+        return f"scenario names must start with sync- or async-: {', '.join(invalid_names)}"
     surface: Final = harness_case.surface
     if surface == "sdk" and not isinstance(suite.route, RouteSpec):
         return "must use RouteSpec for the sdk surface"
@@ -57,15 +62,14 @@ def scenario_nodeids(
     trace_suite: TraceSuite,
     harness_case: HarnessCase,
     selected_scenarios: frozenset[str] = frozenset(),
-) -> tuple[tuple[TraceScenario, TraceMode, str], ...]:
+) -> tuple[tuple[TraceScenario, str], ...]:
     surface: Final = harness_case.surface
     if surface is None:
         return ()
     return tuple(
-        (scenario, mode, f"trace:{surface}:{harness_case.sdk_function}:{scenario.name}:{mode}")
+        (scenario, f"trace:{surface}:{harness_case.sdk_function}:{scenario.name}")
         for scenario in trace_suite.scenarios
         if not selected_scenarios or scenario.name in selected_scenarios
-        for mode in scenario.modes
     )
 
 
@@ -77,54 +81,49 @@ def _record_setup_failure(run: HarnessRun, case: HarnessCase, message: str, stag
     run.failures.append((nodeid, message))
 
 
-def run_trace_mode(
+def run_trace_scenario(
     run: HarnessRun,
     result: CaseResult,
     trace_suite: TraceSuite,
     scenario: TraceScenario,
-    mode: TraceMode,
     surface: Surface,
     nodeid: str,
     on_update: UpdateCallback,
+    engine: TraceEngine = "both",
 ) -> None:
     started_at: Final = monotonic()
-    comparison: Final = _execute_mode(trace_suite, scenario, mode, surface)
+    trace: Final = _execute_scenario(trace_suite, scenario, surface, engine)
     duration: Final = monotonic() - started_at
-    if isinstance(comparison, TraceExecutionFailure):
+    if isinstance(trace, TraceExecutionFailure):
         result.record(nodeid, RunStatus.ERROR, duration)
-        run.failures.append((nodeid, comparison.message))
+        run.failures.append((nodeid, trace.message))
         on_update(run)
         return
-    artifact: Final = ResultArtifact(TRACE_COMPARISON_ARTIFACT, comparison.model_dump_json())
-    if comparison.has_errors():
+    artifact: Final = ResultArtifact(TRACE_ARTIFACT, trace.model_dump_json())
+    if trace.has_errors():
         result.record(nodeid, RunStatus.ERROR, duration, (artifact,))
-        run.failures.append(
-            (nodeid, "\n".join(error for error in (comparison.python_error, comparison.rust_error) if error))
-        )
+        run.failures.append((nodeid, "\n".join(error for error in (trace.python_error, trace.rust_error) if error)))
     else:
-        status: Final = RunStatus.PASSED if comparison.contract_matches() else RunStatus.FAILED
-        result.record(nodeid, status, duration, (artifact,))
-        if status is RunStatus.FAILED:
-            run.failures.append((nodeid, "trace contract mismatch; see the rendered comparison"))
+        result.record(nodeid, RunStatus.PASSED, duration, (artifact,))
     on_update(run)
 
 
-def _execute_mode(
+def _execute_scenario(
     trace_suite: TraceSuite,
     scenario: TraceScenario,
-    mode: TraceMode,
     surface: Surface,
-) -> TraceComparisonArtifact | TraceExecutionFailure:
+    engine: TraceEngine,
+) -> TraceArtifact | TraceExecutionFailure:
     route: Final = trace_suite.route
     if isinstance(route, GatewayRouteSpec):
         if surface != "gateway":
             return TraceExecutionFailure("harness", "gateway route cannot run on the sdk surface")
         from .gateway.execution import execute_gateway_trace
 
-        return execute_gateway_trace(route, scenario, mode)
+        return execute_gateway_trace(route, scenario, engine)
     if surface != "sdk":
         return TraceExecutionFailure("harness", "sdk route cannot run on the gateway surface")
-    return execute_trace(route, scenario, mode, surface)
+    return execute_trace(route, scenario, surface, engine)
 
 
 def _run_case(
@@ -132,6 +131,7 @@ def _run_case(
     harness_case: HarnessCase,
     selected_scenarios: frozenset[str],
     on_update: UpdateCallback,
+    engine: TraceEngine,
 ) -> None:
     result: Final = run.results[harness_case.key]
     spec: Final = harness_case.spec
@@ -146,15 +146,29 @@ def _run_case(
         on_update(run)
         return
     nodeids: Final = scenario_nodeids(trace_suite, harness_case, selected_scenarios)
-    result.collected.update(nodeid for _, _, nodeid in nodeids)
+    result.collected.update(nodeid for _, nodeid in nodeids)
     if not nodeids:
         result.status = RunStatus.SKIPPED
         on_update(run)
         return
     result.status = RunStatus.RUNNING
     on_update(run)
-    for scenario, mode, nodeid in nodeids:
-        run_trace_mode(run, result, trace_suite, scenario, mode, surface, nodeid, on_update)
+    for scenario, nodeid in nodeids:
+        run_trace_scenario(run, result, trace_suite, scenario, surface, nodeid, on_update, engine)
+
+
+def runner_selection(runner_args: Sequence[str]) -> tuple[frozenset[str], TraceEngine]:
+    engine: TraceEngine = "both"
+    scenarios: list[str] = []
+    for argument in runner_args:
+        if argument.startswith("--engine="):
+            value = argument.removeprefix("--engine=")
+            if value not in {"python", "rust"}:
+                raise ValueError(f"invalid trace engine: {value}")
+            engine = cast(TraceEngine, value)
+        else:
+            scenarios.append(argument)
+    return frozenset(scenarios), engine
 
 
 def run_trace_cases(
@@ -163,10 +177,10 @@ def run_trace_cases(
     on_update: UpdateCallback,
     runner_args: Sequence[str] = (),
 ) -> tuple[int, HarnessRun]:
-    selected_scenarios: Final = frozenset(runner_args)
+    selected_scenarios, engine = runner_selection(runner_args)
     run: Final = HarnessRun.from_cases(cases)
     runnable_cases: Final = tuple(case for case in cases if isinstance(case.spec, ModuleCaseSpec))
-    bridge_error: Final = ensure_trace_bridge(repo_root) if runnable_cases else None
+    bridge_error: Final = ensure_trace_bridge(repo_root) if runnable_cases and engine != "python" else None
     if bridge_error is not None:
         for harness_case in runnable_cases:
             _record_setup_failure(run, harness_case, bridge_error, "bridge")
@@ -174,7 +188,7 @@ def run_trace_cases(
         on_update(run)
         return 1, run
     for harness_case in cases:
-        _run_case(run, harness_case, selected_scenarios, on_update)
+        _run_case(run, harness_case, selected_scenarios, on_update, engine)
     run.finished_at = monotonic()
     on_update(run)
     failed: Final = any(

tests/rust-python-harness/strategies/trace_parity/sdk/chat_completions/case.py

@@ -1,10 +1,15 @@
 from __future__ import annotations
 
-import json
 from typing import Final
 
-from .....shared.parity.recorded_http import HttpHeader, RecordedHttpResponse
 from .....shared.tracing.steps import Engine, mapping
+from ...fixtures import (
+    anthropic_response_body,
+    anthropic_stream_events,
+    aws_event_stream_response,
+    json_response,
+    sse_response,
+)
 from ...models import RouteFixture, RouteSpec, TraceScenario, TraceSuite
 
 COMMON_MAPPINGS: Final = (
@@ -24,6 +29,22 @@ COMMON_MAPPINGS: Final = (
     mapping(rust_span="execute_chat_completions_provider_call"),
     mapping(rust_span="http_request", python_frame=r"AsyncHTTPHandler\.post$|HTTPHandler\.post$"),
     mapping(rust_span="transform_response", python_frame=r"(?<!async_)transform_response$"),
+    mapping(span="python_logging_pre_call", python_frame=r"Logging\.pre_call$"),
+    mapping(span="python_logging_post_call", python_frame=r"Logging\.post_call$"),
+    mapping(span="python_success_callback", python_frame=r"Logging\.async_success_handler$|Logging\.success_handler$"),
+)
+
+STREAM_MAPPINGS: Final = (
+    mapping(span="python_stream_wrapper", python_frame=r"CustomStreamWrapper\.__init__$"),
+    mapping(span="python_stream_next", python_frame=r"CustomStreamWrapper\.__next__$|CustomStreamWrapper\.__anext__$"),
+    mapping(span="python_stream_chunk", python_frame=r"CustomStreamWrapper\.chunk_creator$"),
+    mapping(span="python_stream_finalize", python_frame=r"CustomStreamWrapper\._finalize_completed_stream$"),
+)
+
+FAILURE_MAPPINGS: Final = (
+    mapping(span="python_exception_mapping", python_frame=r"(?<!_)exception_type$"),
+    mapping(span="python_failure_callback", python_frame=r"Logging\.failure_handler$"),
+    mapping(span="python_async_failure_callback", python_frame=r"Logging\.async_failure_handler$"),
 )
 
 SYNC_MAPPINGS: Final = (
@@ -44,41 +65,23 @@ ASYNC_MAPPINGS: Final = (
 
 
 def _anthropic_fixture(engine: Engine, _base_url: str) -> RouteFixture:
-    response: Final = json.dumps(
-        {
-            "id": "msg_trace",
-            "type": "message",
-            "role": "assistant",
-            "model": "claude-sonnet-5",
-            "content": [{"type": "text", "text": "hello"}],
-            "stop_reason": "end_turn",
-            "stop_sequence": None,
-            "usage": {"input_tokens": 2, "output_tokens": 3},
-        }
-    ).encode()
     return RouteFixture(
         kwargs={
             "model": "anthropic/claude-sonnet-5",
             "messages": [{"role": "user", "content": "hello"}],
             **({"optional_params": {"max_tokens": 16}} if engine == "rust" else {"max_tokens": 16}),
         },
-        provider_responses=(
-            RecordedHttpResponse.from_bytes(
-                200, (HttpHeader(name="content-type", value="application/json"),), response
-            ),
-        ),
+        provider_responses=(json_response(anthropic_response_body()),),
     )
 
 
 def _bedrock_fixture(engine: Engine, _base_url: str) -> RouteFixture:
-    response: Final = json.dumps(
-        {
-            "output": {"message": {"role": "assistant", "content": [{"text": "hello"}]}},
-            "stopReason": "end_turn",
-            "usage": {"inputTokens": 2, "outputTokens": 3, "totalTokens": 5},
-            "metrics": {"latencyMs": 1},
-        }
-    ).encode()
+    response: Final[dict[str, object]] = {
+        "output": {"message": {"role": "assistant", "content": [{"text": "hello"}]}},
+        "stopReason": "end_turn",
+        "usage": {"inputTokens": 2, "outputTokens": 3, "totalTokens": 5},
+        "metrics": {"latencyMs": 1},
+    }
     credentials: Final = {
         "aws_access_key_id": "test-access",
         "aws_secret_access_key": "test-secret",
@@ -94,11 +97,60 @@ def _bedrock_fixture(engine: Engine, _base_url: str) -> RouteFixture:
                 else {**credentials, "max_tokens": 16}
             ),
         },
+        provider_responses=(json_response(response),),
+    )
+
+
+def _anthropic_stream_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _anthropic_fixture(engine, _base_url)
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(sse_response(anthropic_stream_events()),),
+        consume_stream=True,
+    )
+
+
+def _bedrock_stream_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _bedrock_fixture(engine, _base_url)
+    events: Final[tuple[dict[str, object], ...]] = (
+        {"messageStart": {"role": "assistant"}},
+        {"contentBlockStart": {"contentBlockIndex": 0, "start": {}}},
+        {"contentBlockDelta": {"contentBlockIndex": 0, "delta": {"text": "hello"}}},
+        {"contentBlockStop": {"contentBlockIndex": 0}},
+        {"messageStop": {"stopReason": "end_turn"}},
+        {"metadata": {"usage": {"inputTokens": 2, "outputTokens": 1, "totalTokens": 3}}},
+    )
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(aws_event_stream_response(events),),
+        consume_stream=True,
+    )
+
+
+def _provider_error_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _anthropic_fixture(engine, _base_url)
+    return fixture.derive(
         provider_responses=(
-            RecordedHttpResponse.from_bytes(
-                200, (HttpHeader(name="content-type", value="application/json"),), response
+            json_response(
+                {"type": "error", "error": {"type": "invalid_request_error", "message": "bad request"}},
+                status=400,
             ),
         ),
+        expected_failure=True,
+    )
+
+
+def _stream_error_fixture(engine: Engine, base_url: str) -> RouteFixture:
+    fixture: Final = _anthropic_fixture(engine, base_url)
+    events: Final = (
+        anthropic_stream_events()[0],
+        ("error", {"type": "error", "error": {"type": "overloaded_error", "message": "overloaded"}}),
+    )
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(sse_response(events),),
+        expected_failure=True,
+        consume_stream=True,
     )
 
 
@@ -132,18 +184,64 @@ TRACE_SUITE: Final = TraceSuite(
     route=SPEC,
     scenarios=(
         TraceScenario(
-            name="anthropic",
+            name="sync-anthropic",
             fixture=_anthropic_fixture,
-            mappings=COMMON_MAPPINGS,
-            sync_mappings=SYNC_MAPPINGS,
-            async_mappings=ASYNC_MAPPINGS,
+            mappings=SYNC_MAPPINGS,
+            asynchronous=False,
         ),
         TraceScenario(
-            name="bedrock",
+            name="async-anthropic",
+            fixture=_anthropic_fixture,
+            mappings=ASYNC_MAPPINGS,
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-anthropic-stream",
+            fixture=_anthropic_stream_fixture,
+            mappings=(*SYNC_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=False,
+        ),
+        TraceScenario(
+            name="async-anthropic-stream",
+            fixture=_anthropic_stream_fixture,
+            mappings=(*ASYNC_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-anthropic-provider-error",
+            fixture=_provider_error_fixture,
+            mappings=(*ASYNC_MAPPINGS, *FAILURE_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-anthropic-stream-error",
+            fixture=_stream_error_fixture,
+            mappings=(*ASYNC_MAPPINGS, *STREAM_MAPPINGS, *FAILURE_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-bedrock",
             fixture=_bedrock_fixture,
-            mappings=BEDROCK_COMMON_MAPPINGS,
-            sync_mappings=BEDROCK_SYNC_MAPPINGS,
-            async_mappings=BEDROCK_ASYNC_MAPPINGS,
+            mappings=BEDROCK_SYNC_MAPPINGS,
+            asynchronous=False,
+        ),
+        TraceScenario(
+            name="async-bedrock",
+            fixture=_bedrock_fixture,
+            mappings=BEDROCK_ASYNC_MAPPINGS,
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-bedrock-event-stream",
+            fixture=_bedrock_stream_fixture,
+            mappings=(*BEDROCK_SYNC_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=False,
+        ),
+        TraceScenario(
+            name="async-bedrock-event-stream",
+            fixture=_bedrock_stream_fixture,
+            mappings=(*BEDROCK_ASYNC_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=True,
         ),
     ),
 )

tests/rust-python-harness/strategies/trace_parity/sdk/execution.py

@@ -1,18 +1,20 @@
 from __future__ import annotations
 
 import asyncio
-from collections.abc import Awaitable
+import os
+from collections.abc import AsyncIterable, Awaitable, Iterable
 from dataclasses import dataclass
 from pathlib import Path
 from typing import Final, Protocol, cast
+from unittest.mock import patch
 
 from ....shared.parity.replay import replay_server
 from ....shared.reporting.models import Surface
 from ....shared.tracing.native import TraceResponsePayload, native_trace_events
 from ....shared.tracing.profiler import FunctionTraceEvent, profile_python
 from ....shared.tracing.steps import Engine, pipeline_projection
-from ..models import RouteFixture, RouteSpec, TraceExecutionFailure, TraceMode, TraceScenario
-from ..reporting import TraceComparisonArtifact
+from ..models import RouteFixture, RouteSpec, TraceEngine, TraceExecutionFailure, TraceScenario
+from ..reporting import TraceArtifact
 
 
 class SdkCall(Protocol):
@@ -25,10 +27,20 @@ class _CollectedTrace:
     error: str | None = None
 
 
-def _invoke(function: SdkCall, kwargs: dict[str, object], *, asynchronous: bool) -> object:
+def _invoke(
+    function: SdkCall,
+    kwargs: dict[str, object],
+    *,
+    asynchronous: bool,
+    consume_stream: bool = False,
+) -> object:
     async def invoke_async() -> object:
         try:
-            return await cast(Awaitable[object], function(**kwargs))
+            response: Final = await cast(Awaitable[object], function(**kwargs))
+            if consume_stream and isinstance(response, AsyncIterable):
+                stream = cast(AsyncIterable[object], response)
+                return tuple([item async for item in stream])
+            return response
         finally:
             await asyncio.sleep(0)
             from litellm.litellm_core_utils.logging_worker import GLOBAL_LOGGING_WORKER
@@ -38,7 +50,10 @@ def _invoke(function: SdkCall, kwargs: dict[str, object], *, asynchronous: bool)
 
     if asynchronous:
         return asyncio.run(invoke_async())
-    return function(**kwargs)
+    response: Final = function(**kwargs)
+    if consume_stream and isinstance(response, Iterable):
+        return tuple(cast(Iterable[object], response))
+    return response
 
 
 def _entrypoint(spec: RouteSpec, engine: Engine, *, asynchronous: bool) -> SdkCall | TraceExecutionFailure:
@@ -47,6 +62,8 @@ def _entrypoint(spec: RouteSpec, engine: Engine, *, asynchronous: bool) -> SdkCa
     from litellm.rust_bridge import get_native_bridge
 
     if engine == "rust":
+        if spec.rust_entrypoints is None:
+            return TraceExecutionFailure("rust", f"{spec.route} has no native Rust trace entrypoint")
         bridge: Final = cast(object | None, get_native_bridge())
         if bridge is None:
             return TraceExecutionFailure("rust", "native Rust bridge is required for trace parity")
@@ -62,14 +79,6 @@ def _entrypoint(spec: RouteSpec, engine: Engine, *, asynchronous: bool) -> SdkCa
     return cast(SdkCall, getattr(owner, spec.python_entrypoints[int(asynchronous)]))
 
 
-def _python_invocation_error(function: SdkCall, kwargs: dict[str, object], *, asynchronous: bool) -> str | None:
-    try:
-        _invoke(function, kwargs, asynchronous=asynchronous)
-    except Exception as error:
-        return f"{type(error).__name__}: {error}"
-    return None
-
-
 def _collect(
     function: SdkCall,
     fixture: RouteFixture,
@@ -83,14 +92,23 @@ def _collect(
         return _CollectedTrace(native_trace_events(payload), payload.error)
     import litellm
 
-    with profile_python(Path(litellm.__file__).parent, threads=True) as profiler:
-        error: Final = _python_invocation_error(function, kwargs, asynchronous=asynchronous)
+    previous_suppress_debug_info: Final = litellm.suppress_debug_info
+    try:
+        if fixture.expected_failure:
+            litellm.suppress_debug_info = True
+        with profile_python(Path(litellm.__file__).parent, threads=True) as profiler:
+            error: str | None
+            try:
+                _invoke(function, kwargs, asynchronous=asynchronous, consume_stream=fixture.consume_stream)
+                error = None
+            except Exception as caught:
+                error = f"{type(caught).__name__}: {caught}"
+    finally:
+        litellm.suppress_debug_info = previous_suppress_debug_info
     return _CollectedTrace(tuple(profiler.events), error)
 
 
-def collect_trace(
-    spec: RouteSpec, engine: Engine, *, asynchronous: bool
-) -> tuple[FunctionTraceEvent, ...] | TraceExecutionFailure:
+def collect_trace(spec: RouteSpec, engine: Engine, *, asynchronous: bool) -> tuple[FunctionTraceEvent, ...] | TraceExecutionFailure:
     function: Final = _entrypoint(spec, engine, asynchronous=asynchronous)
     if isinstance(function, TraceExecutionFailure):
         return function
@@ -101,15 +119,18 @@ def collect_trace(
                 provider.enqueue_response(response)
             fixture: Final = RouteFixture(
                 kwargs={
-                    **base_fixture.kwargs,
                     "api_key": "test-key",
+                    **base_fixture.kwargs,
                     "api_base": provider.url,
                     **({"timeout_seconds": 5} if engine == "rust" else {"timeout": 5}),
                 },
                 provider_responses=base_fixture.provider_responses,
                 expected_failure=base_fixture.expected_failure,
+                consume_stream=base_fixture.consume_stream,
+                environment=base_fixture.environment,
             )
-            collected: Final = _collect(function, fixture, engine, asynchronous=asynchronous)
+            with patch.dict(os.environ, fixture.environment):
+                collected: Final = _collect(function, fixture, engine, asynchronous=asynchronous)
             provider.take_requests(len(fixture.provider_responses))
     except Exception as error:
         return TraceExecutionFailure(engine, f"{type(error).__name__}: {error}")
@@ -129,48 +150,56 @@ def _failure_message(result: tuple[FunctionTraceEvent, ...] | TraceExecutionFail
 
 
 def execute_trace(
-    route: RouteSpec, scenario: TraceScenario, mode: TraceMode, surface: Surface
-) -> TraceComparisonArtifact:
-    asynchronous: Final = mode == "async"
-    mappings: Final = scenario.mappings_for(mode)
+    route: RouteSpec,
+    scenario: TraceScenario,
+    surface: Surface,
+    engine: TraceEngine = "both",
+) -> TraceArtifact:
+    effective_engine: Final[TraceEngine] = "python" if engine == "both" and route.rust_entrypoints is None else engine
     scenario_route: Final = RouteSpec(
         route=route.route,
         python_entrypoints=route.python_entrypoints,
         rust_entrypoints=route.rust_entrypoints,
         fixture=scenario.fixture,
     )
-    python_trace: Final = collect_trace(scenario_route, "python", asynchronous=asynchronous)
-    rust_trace: Final = collect_trace(scenario_route, "rust", asynchronous=asynchronous)
+    python_trace: Final = (
+        collect_trace(
+            scenario_route,
+            "python",
+            asynchronous=scenario.asynchronous,
+        )
+        if effective_engine != "rust"
+        else ()
+    )
+    rust_trace: Final = (
+        collect_trace(scenario_route, "rust", asynchronous=scenario.asynchronous)
+        if effective_engine != "python"
+        else ()
+    )
     python_error: Final = _failure_message(python_trace)
     rust_error: Final = _failure_message(rust_trace)
     python_events: Final = python_trace if isinstance(python_trace, tuple) else ()
     rust_events: Final = rust_trace if isinstance(rust_trace, tuple) else ()
     try:
-        python: Final = pipeline_projection("python", python_events, mappings)
-        rust: Final = pipeline_projection("rust", rust_events, mappings)
+        python: Final = pipeline_projection("python", python_events)
+        rust: Final = pipeline_projection("rust", rust_events)
     except ValueError as error:
-        return TraceComparisonArtifact.from_traces(
+        return TraceArtifact.from_traces(
+            engine=effective_engine,
             surface=surface,
             sdk_function=route.route,
             scenario=scenario.name,
-            mode=mode,
-            mappings=mappings,
-            contract=scenario.contract,
             python=(),
             rust=(),
-            python_unmatched=0,
             python_error=f"harness: {error}",
         )
-    return TraceComparisonArtifact.from_traces(
+    return TraceArtifact.from_traces(
+        engine=effective_engine,
         surface=surface,
         sdk_function=route.route,
         scenario=scenario.name,
-        mode=mode,
-        mappings=mappings,
-        contract=scenario.contract,
         python=python.steps,
         rust=rust.steps,
-        python_unmatched=python.unmatched,
         python_error=python_error,
         rust_error=rust_error,
     )

tests/rust-python-harness/strategies/trace_parity/sdk/messages/case.py

@@ -1,14 +1,26 @@
 from __future__ import annotations
 
-import json
 from typing import Final
 
-from .....shared.parity.recorded_http import HttpHeader, RecordedHttpResponse
 from .....shared.tracing.steps import Engine, mapping
+from ...fixtures import (
+    anthropic_response_body,
+    anthropic_stream_events,
+    aws_event_stream_response,
+    json_response,
+    sse_response,
+)
 from ...models import RouteFixture, RouteSpec, TraceScenario, TraceSuite
 
 COMMON_MAPPINGS: Final = (
     mapping(rust_span="messages", python_frame=r"anthropic_interface/messages/__init__\.py:\d+ a?create$"),
+    mapping(span="python_sanitize_empty_content", python_frame=r"strip_empty_content_blocks_from_anthropic_messages$"),
+    mapping(span="python_sanitize_tool_ids", python_frame=r"sanitize_tool_use_ids_in_anthropic_messages$"),
+    mapping(
+        span="python_flatten_web_search", python_frame=r"flatten_unencrypted_web_search_results_in_anthropic_messages$"
+    ),
+    mapping(span="python_cache_control", python_frame=r"AnthropicCacheControlHook\.maybe_inject_cache_control$"),
+    mapping(span="python_pre_request_hooks", python_frame=r"_execute_pre_request_hooks$"),
     mapping(
         span="python_messages_provider_config",
         python_frame=r"ProviderConfigManager\.get_provider_anthropic_messages_config$",
@@ -30,10 +42,42 @@ COMMON_MAPPINGS: Final = (
     ),
     mapping(rust_span="http_request", python_frame=r"AsyncHTTPHandler\.post$|HTTPHandler\.post$"),
     mapping(rust_span="transform_response", python_frame=r"(?<!async_)transform_anthropic_messages_response$"),
+    mapping(span="python_logging_pre_call", python_frame=r"Logging\.pre_call$"),
+    mapping(span="python_logging_post_call", python_frame=r"Logging\.post_call$"),
+)
+
+SUCCESS_MAPPINGS: Final = (mapping(span="python_success_callback", python_frame=r"Logging\.async_success_handler$"),)
+FAILURE_MAPPINGS: Final = (
+    mapping(span="python_failure_callback", python_frame=r"Logging\.failure_handler$"),
+    mapping(span="python_async_failure_callback", python_frame=r"Logging\.async_failure_handler$"),
+    mapping(span="python_exception_mapping", python_frame=r"(?<!_)exception_type$"),
+)
+STREAM_MAPPINGS: Final = (
+    mapping(span="python_stream_wrapper", python_frame=r"AnthropicMessagesStreamingResponse\.__init__$"),
+    mapping(span="python_stream_next", python_frame=r"AnthropicMessagesStreamingResponse\.__anext__$"),
+    mapping(
+        span="python_stream_iterator",
+        python_frame=r"BaseAnthropicMessagesStreamingIterator\.get_async_streaming_response_iterator$",
+    ),
+    mapping(span="python_stream_chunks", python_frame=r"PassThroughStreamingHandler\.chunk_processor$"),
+    mapping(
+        span="python_stream_logging",
+        python_frame=r"PassThroughStreamingHandler\._route_streaming_logging_to_handler$",
+    ),
 )
 
 ANTHROPIC_MAPPINGS: Final = (
     *COMMON_MAPPINGS,
+    *SUCCESS_MAPPINGS,
+    mapping(
+        rust_span="transform_request",
+        python_frame=r"(?<!Azure)AnthropicMessagesConfig\.transform_anthropic_messages_request$",
+    ),
+)
+
+ANTHROPIC_FAILURE_MAPPINGS: Final = (
+    *COMMON_MAPPINGS,
+    *FAILURE_MAPPINGS,
     mapping(
         rust_span="transform_request",
         python_frame=r"(?<!Azure)AnthropicMessagesConfig\.transform_anthropic_messages_request$",
@@ -42,6 +86,7 @@ ANTHROPIC_MAPPINGS: Final = (
 
 AZURE_MAPPINGS: Final = (
     *COMMON_MAPPINGS,
+    *SUCCESS_MAPPINGS,
     mapping(
         rust_span="transform_request",
         python_frame=r"AzureAnthropicMessagesConfig\.transform_anthropic_messages_request$",
@@ -52,31 +97,54 @@ AZURE_MAPPINGS: Final = (
     ),
 )
 
+BEDROCK_MAPPINGS: Final = (
+    *COMMON_MAPPINGS,
+    *SUCCESS_MAPPINGS,
+    mapping(
+        rust_span="transform_request",
+        python_frame=r"AmazonAnthropicClaudeMessagesConfig\.transform_anthropic_messages_request$",
+    ),
+    mapping(
+        span="python_anthropic_transform_request",
+        python_frame=r"(?<!Azure)AnthropicMessagesConfig\.transform_anthropic_messages_request$",
+    ),
+    mapping(
+        span="python_bedrock_provider_config",
+        python_frame=r"BedrockModelInfo\.get_bedrock_provider_config_for_messages_api$",
+    ),
+    mapping(span="python_aws_signing", python_frame=r"sign_request_off_loop_if_aws$"),
+    mapping(
+        span="python_aws_sign_request",
+        python_frame=r"AmazonAnthropicClaudeMessagesConfig\.sign_request$|BaseAWSLLM\._sign_request$",
+    ),
+)
+
+RETRY_MAPPINGS: Final = (
+    *BEDROCK_MAPPINGS,
+    mapping(
+        span="python_retry_request_transform",
+        python_frame=r"transform_anthropic_messages_request_on_http_error$",
+    ),
+    mapping(
+        span="python_strip_invalid_thinking",
+        python_frame=r"strip_thinking_blocks_from_anthropic_messages_request_dict$",
+    ),
+)
+
+MOCK_MAPPINGS: Final = (
+    *COMMON_MAPPINGS,
+    mapping(span="python_mock_response", python_frame=r"messages/utils\.py:\d+ mock_response$"),
+)
+
 
 def _fixture(engine: Engine, provider: str) -> RouteFixture:
     conversation: Final = {"messages": [{"role": "user", "content": "hello"}], "max_tokens": 16}
-    response: Final = json.dumps(
-        {
-            "id": "msg_trace",
-            "type": "message",
-            "role": "assistant",
-            "model": "claude-sonnet-5",
-            "content": [{"type": "text", "text": "hello"}],
-            "stop_reason": "end_turn",
-            "stop_sequence": None,
-            "usage": {"input_tokens": 2, "output_tokens": 3},
-        }
-    ).encode()
     return RouteFixture(
         kwargs={
             "model": f"{provider}/claude-sonnet-5",
             **({"body": {**conversation, "model": "claude-sonnet-5"}} if engine == "rust" else conversation),
         },
-        provider_responses=(
-            RecordedHttpResponse.from_bytes(
-                200, (HttpHeader(name="content-type", value="application/json"),), response
-            ),
-        ),
+        provider_responses=(json_response(anthropic_response_body()),),
     )
 
 
@@ -88,11 +156,170 @@ def _azure_fixture(engine: Engine, _base_url: str) -> RouteFixture:
     return _fixture(engine, "azure_ai")
 
 
+def _bedrock_kwargs(engine: Engine) -> dict[str, object]:
+    conversation: Final = {"messages": [{"role": "user", "content": "hello"}], "max_tokens": 16}
+    return {
+        "model": "bedrock/anthropic.claude-3-sonnet-20240229-v1:0",
+        **(
+            {"body": {**conversation, "model": "anthropic.claude-3-sonnet-20240229-v1:0"}}
+            if engine == "rust"
+            else conversation
+        ),
+        "aws_access_key_id": "AKIAIOSFODNN7EXAMPLE",
+        "aws_secret_access_key": "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY",
+        "aws_region_name": "us-east-1",
+    }
+
+
+def _bedrock_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    response_fixture: Final = _fixture(engine, "anthropic")
+    return RouteFixture(kwargs=_bedrock_kwargs(engine), provider_responses=response_fixture.provider_responses)
+
+
+def _bedrock_retry_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    success_fixture: Final = _bedrock_fixture(engine, _base_url)
+    messages: Final = [
+        {"role": "user", "content": "hello"},
+        {
+            "role": "assistant",
+            "content": [
+                {"type": "thinking", "thinking": "old reasoning", "signature": ""},
+                {"type": "text", "text": "partial answer"},
+            ],
+        },
+        {"role": "user", "content": "continue"},
+    ]
+    kwargs: Final = {
+        **_bedrock_kwargs(engine),
+        **(
+            {"body": {"messages": messages, "max_tokens": 16, "model": "anthropic.claude-3-sonnet-20240229-v1:0"}}
+            if engine == "rust"
+            else {"messages": messages}
+        ),
+    }
+    return success_fixture.derive(
+        kwargs=kwargs,
+        provider_responses=(
+            json_response({"message": "messages.1.content.0: Invalid `signature` in `thinking` block"}, status=400),
+            *success_fixture.provider_responses,
+        ),
+    )
+
+
+def _mock_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _fixture(engine, "anthropic")
+    return fixture.derive(kwargs={"mock_response": "hello from mock"}, provider_responses=())
+
+
+def _provider_error_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _fixture(engine, "anthropic")
+    return fixture.derive(
+        provider_responses=(
+            json_response(
+                {"type": "error", "error": {"type": "invalid_request_error", "message": "bad request"}},
+                status=400,
+            ),
+        ),
+        expected_failure=True,
+    )
+
+
+def _sync_unsupported_fixture(engine: Engine, base_url: str) -> RouteFixture:
+    if engine == "rust":
+        return _anthropic_fixture(engine, base_url)
+    fixture: Final = _fixture(engine, "anthropic")
+    return fixture.derive(provider_responses=(), expected_failure=True)
+
+
+def _stream_fixture_for(engine: Engine, provider: str) -> RouteFixture:
+    fixture: Final = _fixture(engine, provider)
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(sse_response(anthropic_stream_events()),),
+        consume_stream=True,
+    )
+
+
+def _stream_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    return _stream_fixture_for(engine, "anthropic")
+
+
+def _azure_stream_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    return _stream_fixture_for(engine, "azure_ai")
+
+
+def _bedrock_stream_fixture(engine: Engine, base_url: str) -> RouteFixture:
+    fixture: Final = _bedrock_fixture(engine, base_url)
+    events: Final = tuple(payload for _, payload in anthropic_stream_events())
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(aws_event_stream_response(events),),
+        consume_stream=True,
+    )
+
+
+def _bedrock_stream_error_fixture(engine: Engine, base_url: str) -> RouteFixture:
+    fixture: Final = _bedrock_fixture(engine, base_url)
+    start: Final = anthropic_stream_events(model="anthropic.claude-3-sonnet-20240229-v1:0")[0][1]
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(aws_event_stream_response((start, {"type": "message_stop"}), corrupt_last_frame=True),),
+        expected_failure=True,
+        consume_stream=True,
+    )
+
+
 SPEC: Final = RouteSpec("messages", ("create", "acreate"), ("messages", "amessages"), _anthropic_fixture)
 TRACE_SUITE: Final = TraceSuite(
     route=SPEC,
     scenarios=(
-        TraceScenario(name="anthropic", fixture=_anthropic_fixture, mappings=ANTHROPIC_MAPPINGS, modes=("async",)),
-        TraceScenario(name="azure-ai", fixture=_azure_fixture, mappings=AZURE_MAPPINGS, modes=("async",)),
+        TraceScenario(
+            name="async-anthropic", fixture=_anthropic_fixture, mappings=ANTHROPIC_MAPPINGS, asynchronous=True
+        ),
+        TraceScenario(name="async-azure-ai", fixture=_azure_fixture, mappings=AZURE_MAPPINGS, asynchronous=True),
+        TraceScenario(name="async-bedrock", fixture=_bedrock_fixture, mappings=BEDROCK_MAPPINGS, asynchronous=True),
+        TraceScenario(
+            name="async-bedrock-invalid-thinking-retry",
+            fixture=_bedrock_retry_fixture,
+            mappings=RETRY_MAPPINGS,
+            asynchronous=True,
+        ),
+        TraceScenario(name="async-mock-response", fixture=_mock_fixture, mappings=MOCK_MAPPINGS, asynchronous=True),
+        TraceScenario(
+            name="async-anthropic-provider-error",
+            fixture=_provider_error_fixture,
+            mappings=ANTHROPIC_FAILURE_MAPPINGS,
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-anthropic-stream",
+            fixture=_stream_fixture,
+            mappings=(*ANTHROPIC_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-azure-ai-stream",
+            fixture=_azure_stream_fixture,
+            mappings=(*AZURE_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-bedrock-event-stream",
+            fixture=_bedrock_stream_fixture,
+            mappings=(*BEDROCK_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-bedrock-event-stream-error",
+            fixture=_bedrock_stream_error_fixture,
+            mappings=(*BEDROCK_MAPPINGS, *STREAM_MAPPINGS, *FAILURE_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-unsupported",
+            fixture=_sync_unsupported_fixture,
+            mappings=ANTHROPIC_MAPPINGS,
+            asynchronous=False,
+        ),
     ),
 )

tests/rust-python-harness/strategies/trace_parity/sdk/ocr/case.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import json
-from typing import Final, cast
+from typing import Final
 
 from .....shared.parity.recorded_http import HttpHeader, RecordedHttpResponse
 from .....shared.tracing.steps import Engine, mapping
@@ -53,6 +53,23 @@ ASYNC_MAPPINGS: Final = (
     ),
 )
 
+PUBLIC_RUST_DISPATCH_MAPPINGS: Final = (
+    mapping(span="public_sdk_entrypoint", python_frame=r"ocr/main\.py:\d+ a?ocr$"),
+    mapping(span="public_request", python_frame=r"ocr/main\.py:\d+ _public_request$"),
+    mapping(span="bind_request", python_frame=r"ocr/main\.py:\d+ _bind_request$"),
+    mapping(span="rust_ocr_enabled", python_frame=r"rust_bridge/configuration\.py:\d+ rust_ocr_enabled$"),
+    mapping(span="select_native_ocr", python_frame=r"rust_bridge/ocr_lifecycle\.py:\d+ select$"),
+    mapping(span="load_native_bridge", python_frame=r"rust_bridge/bindings\.py:\d+ NativeBinding\.load$"),
+    mapping(span="native_call_setup", python_frame=r"rust_bridge/lifecycle\.py:\d+ setup$"),
+    mapping(span="native_response", python_frame=r"rust_bridge/ocr\.py:\d+ _response$"),
+    mapping(span="native_call_finalize", python_frame=r"rust_bridge/lifecycle\.py:\d+ finalize$"),
+    mapping(
+        span="native_success_bookkeeping",
+        python_frame=r"rust_bridge/lifecycle\.py:\d+ success_bookkeeping$",
+    ),
+    *(mapping(rust_span=item.rust) for item in SYNC_MAPPINGS if item.rust is not None),
+)
+
 CALLBACK_SUCCESS_SYNC_MAPPINGS: Final = (*SYNC_MAPPINGS, SUCCESS_CALLBACK_SYNC_MAPPING)
 CALLBACK_SUCCESS_ASYNC_MAPPINGS: Final = (*ASYNC_MAPPINGS, SUCCESS_CALLBACK_ASYNC_MAPPING)
 CALLBACK_FAILURE_SYNC_MAPPINGS: Final = (
@@ -164,23 +181,6 @@ def _azure_fixture(engine: Engine, _base_url: str) -> RouteFixture:
     )
 
 
-def _vertex_fixture(engine: Engine, _base_url: str) -> RouteFixture:
-    fixture: Final = _fixture(
-        engine,
-        "vertex_ai/mistral-ocr-maas",
-        {"type": "image_url", "image_url": "data:image/png;base64,aGVsbG8="},
-    )
-    vertex: Final = {"vertex_project": "trace-project", "vertex_location": "us-central1"}
-    optional_params: Final = cast(dict[str, object], fixture.kwargs.get("optional_params", {}))
-    return RouteFixture(
-        kwargs={
-            **fixture.kwargs,
-            **({"optional_params": {**optional_params, **vertex}} if engine == "rust" else vertex),
-        },
-        provider_responses=fixture.provider_responses,
-    )
-
-
 def _vertex_deepseek_fixture(engine: Engine, _base_url: str) -> RouteFixture:
     vertex: Final = {"vertex_project": "trace-project", "vertex_location": "us-central1"}
     return RouteFixture(
@@ -204,6 +204,62 @@ def _vertex_deepseek_fixture(engine: Engine, _base_url: str) -> RouteFixture:
     )
 
 
+def _vertex_deepseek_credentials_fixture(engine: Engine, base_url: str) -> RouteFixture:
+    from cryptography.hazmat.primitives import serialization
+    from cryptography.hazmat.primitives.asymmetric import rsa
+
+    fixture: Final = _vertex_deepseek_fixture(engine, base_url)
+    private_key: Final = rsa.generate_private_key(public_exponent=65537, key_size=2048)
+    credentials: Final = json.dumps(
+        {
+            "type": "service_account",
+            "project_id": "trace-project",
+            "private_key_id": "trace-key",
+            "private_key": private_key.private_bytes(
+                serialization.Encoding.PEM,
+                serialization.PrivateFormat.PKCS8,
+                serialization.NoEncryption(),
+            ).decode(),
+            "client_email": "trace@trace-project.iam.gserviceaccount.com",
+            "token_uri": f"{base_url}/token",
+        }
+    )
+    return RouteFixture(
+        kwargs={**fixture.kwargs, "api_key": None},
+        environment=(("VERTEXAI_CREDENTIALS", credentials), ("VERTEX_AI_API_KEY", "")),
+        provider_responses=(
+            RecordedHttpResponse.from_bytes(
+                200,
+                (HttpHeader(name="content-type", value="application/json"),),
+                b'{"access_token":"trace-token","token_type":"Bearer","expires_in":3600}',
+            ),
+            *fixture.provider_responses,
+        ),
+    )
+
+
+def _cohere_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    return RouteFixture(
+        kwargs={
+            "model": "cohere/parse-v5.0",
+            "document": {"type": "image_url", "image_url": "data:image/png;base64,aGVsbG8="},
+            **({"optional_params": {"output_format": "blocks"}} if engine == "rust" else {"output_format": "blocks"}),
+        },
+        provider_responses=(
+            RecordedHttpResponse.from_bytes(
+                200,
+                (HttpHeader(name="content-type", value="application/json"),),
+                json.dumps(
+                    {
+                        "pages": [{"index": 0, "blocks": [{"type": "text", "text": {"content": "hello"}}]}],
+                        "meta": {"billed_units": {"pages": 1}},
+                    }
+                ).encode(),
+            ),
+        ),
+    )
+
+
 def _azure_document_intelligence_fixture(engine: Engine, base_url: str) -> RouteFixture:
     completed: Final = json.dumps(
         {
@@ -249,30 +305,6 @@ def _azure_document_intelligence_fixture(engine: Engine, base_url: str) -> Route
     )
 
 
-VERTEX_COMMON_MAPPINGS: Final = (
-    *COMMON_MAPPINGS[:7],
-    mapping(
-        rust_span="transform_ocr_request",
-        python_frame=(
-            r"VertexAIOCRConfig\.(?:async_)?transform_ocr_request$"
-            r"|MistralOCRConfig\.transform_ocr_request$"
-        ),
-    ),
-    COMMON_MAPPINGS[-1],
-)
-VERTEX_SYNC_MAPPINGS: Final = (
-    *VERTEX_COMMON_MAPPINGS,
-    mapping(rust_span="execute_ocr_provider_call", python_frame=r"BaseLLMHTTPHandler\.ocr$"),
-    mapping(span="python_transform_ocr_response_wrapper", python_frame=r"BaseLLMHTTPHandler\._transform_ocr_response$"),
-    mapping(rust_span="transform_ocr_response", python_frame=r"MistralOCRConfig\.transform_ocr_response$"),
-)
-VERTEX_ASYNC_MAPPINGS: Final = (
-    *VERTEX_COMMON_MAPPINGS,
-    mapping(span="python_ocr_wrapper", python_frame=r"BaseLLMHTTPHandler\.ocr$"),
-    mapping(rust_span="execute_ocr_provider_call", python_frame=r"BaseLLMHTTPHandler\.async_ocr$"),
-    mapping(rust_span="transform_ocr_response", python_frame=r"MistralOCRConfig\.transform_ocr_response$"),
-)
-
 DEEPSEEK_COMMON_MAPPINGS: Final = (
     mapping(rust_span="ocr", python_frame=r"ocr/main\.py:\d+ a?ocr$"),
     mapping(rust_span="prepare_ocr_call", python_frame=r"ocr/main\.py:\d+ _prepare_ocr_request$"),
@@ -352,59 +384,126 @@ DOCUMENT_INTELLIGENCE_ASYNC_MAPPINGS: Final = (
     mapping(span="python_poll_http_request", python_frame=r"AsyncHTTPHandler\.get$"),
 )
 
+COHERE_COMMON_MAPPINGS: Final = (
+    *COMMON_MAPPINGS[:7],
+    mapping(
+        rust_span="transform_ocr_request",
+        python_frame=r"CohereParseConfig\.(?:async_)?transform_ocr_request$",
+    ),
+    COMMON_MAPPINGS[-1],
+    mapping(rust_span="transform_ocr_response", python_frame=r"CohereParseConfig\.transform_ocr_response$"),
+)
+COHERE_ASYNC_MAPPINGS: Final = (
+    *COHERE_COMMON_MAPPINGS,
+    mapping(span="python_ocr_wrapper", python_frame=r"BaseLLMHTTPHandler\.ocr$"),
+    mapping(rust_span="execute_ocr_provider_call", python_frame=r"BaseLLMHTTPHandler\.async_ocr$"),
+)
 
 SPEC: Final = RouteSpec("ocr", ("ocr", "aocr"), ("ocr", "aocr"), _mistral_fixture)
 TRACE_SUITE: Final = TraceSuite(
     route=SPEC,
     scenarios=(
         TraceScenario(
-            name="mistral",
+            name="sync-mistral",
             fixture=_mistral_fixture,
-            mappings=COMMON_MAPPINGS,
-            sync_mappings=(*SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
-            async_mappings=(*ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            mappings=(*SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=False,
         ),
         TraceScenario(
-            name="mistral-callback-success",
+            name="async-mistral",
+            fixture=_mistral_fixture,
+            mappings=(*ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-mistral-callback-success",
             fixture=_mistral_callback_success_fixture,
-            mappings=COMMON_MAPPINGS,
-            sync_mappings=CALLBACK_SUCCESS_SYNC_MAPPINGS,
-            async_mappings=CALLBACK_SUCCESS_ASYNC_MAPPINGS,
+            mappings=CALLBACK_SUCCESS_SYNC_MAPPINGS,
+            asynchronous=False,
         ),
         TraceScenario(
-            name="mistral-callback-failure",
+            name="async-mistral-callback-success",
+            fixture=_mistral_callback_success_fixture,
+            mappings=CALLBACK_SUCCESS_ASYNC_MAPPINGS,
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-mistral-callback-failure",
             fixture=_mistral_callback_failure_fixture,
-            mappings=(*COMMON_MAPPINGS, FAILURE_CALLBACK_MAPPING),
-            sync_mappings=CALLBACK_FAILURE_SYNC_MAPPINGS,
-            async_mappings=CALLBACK_FAILURE_ASYNC_MAPPINGS,
+            mappings=CALLBACK_FAILURE_SYNC_MAPPINGS,
+            asynchronous=False,
         ),
         TraceScenario(
-            name="azure-ai",
+            name="async-mistral-callback-failure",
+            fixture=_mistral_callback_failure_fixture,
+            mappings=CALLBACK_FAILURE_ASYNC_MAPPINGS,
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-azure-ai",
             fixture=_azure_fixture,
-            mappings=AZURE_COMMON_MAPPINGS,
-            sync_mappings=(*AZURE_SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
-            async_mappings=(*AZURE_ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            mappings=(*AZURE_SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=False,
         ),
         TraceScenario(
-            name="azure-document-intelligence",
+            name="async-azure-ai",
+            fixture=_azure_fixture,
+            mappings=(*AZURE_ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-azure-document-intelligence",
             fixture=_azure_document_intelligence_fixture,
-            mappings=DOCUMENT_INTELLIGENCE_COMMON_MAPPINGS,
-            sync_mappings=(*DOCUMENT_INTELLIGENCE_SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
-            async_mappings=(*DOCUMENT_INTELLIGENCE_ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            mappings=(*DOCUMENT_INTELLIGENCE_SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=False,
         ),
         TraceScenario(
-            name="vertex-ai",
-            fixture=_vertex_fixture,
-            mappings=VERTEX_COMMON_MAPPINGS,
-            sync_mappings=(*VERTEX_SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
-            async_mappings=(*VERTEX_ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            name="async-azure-document-intelligence",
+            fixture=_azure_document_intelligence_fixture,
+            mappings=(*DOCUMENT_INTELLIGENCE_ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=True,
         ),
         TraceScenario(
-            name="vertex-deepseek",
+            name="sync-vertex-deepseek",
             fixture=_vertex_deepseek_fixture,
-            mappings=DEEPSEEK_COMMON_MAPPINGS,
-            sync_mappings=(*DEEPSEEK_SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
-            async_mappings=(*DEEPSEEK_ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            mappings=(*DEEPSEEK_SYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=False,
+        ),
+        TraceScenario(
+            name="async-vertex-deepseek",
+            fixture=_vertex_deepseek_fixture,
+            mappings=(*DEEPSEEK_ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-vertex-deepseek-credentials",
+            fixture=_vertex_deepseek_credentials_fixture,
+            mappings=DEEPSEEK_SYNC_MAPPINGS,
+            asynchronous=False,
+        ),
+        TraceScenario(
+            name="async-vertex-deepseek-credentials",
+            fixture=_vertex_deepseek_credentials_fixture,
+            mappings=DEEPSEEK_ASYNC_MAPPINGS,
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-cohere",
+            fixture=_cohere_fixture,
+            mappings=(*COHERE_ASYNC_MAPPINGS, IGNORED_SUCCESS_CALLBACK_MAPPING),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="sync-public-rust-dispatch",
+            fixture=_mistral_fixture,
+            mappings=PUBLIC_RUST_DISPATCH_MAPPINGS,
+            asynchronous=False,
+        ),
+        TraceScenario(
+            name="async-public-rust-dispatch",
+            fixture=_mistral_fixture,
+            mappings=PUBLIC_RUST_DISPATCH_MAPPINGS,
+            asynchronous=True,
         ),
     ),
 )

tests/rust-python-harness/strategies/trace_parity/sdk/responses/case.py

@@ -0,0 +1,216 @@
+from __future__ import annotations
+
+from typing import Final
+
+from .....shared.tracing.steps import Engine, mapping
+from ...fixtures import (
+    anthropic_response_body,
+    anthropic_stream_events,
+    json_response,
+    responses_body,
+    responses_stream_events,
+    sse_response,
+)
+from ...models import RouteFixture, RouteSpec, TraceScenario, TraceSuite
+
+COMMON_MAPPINGS: Final = (
+    mapping(span="python_responses", python_frame=r"responses/main\.py:\d+ a?responses$"),
+    mapping(
+        span="python_responses_provider_config",
+        python_frame=r"ProviderConfigManager\.get_provider_responses_api_config$",
+    ),
+    mapping(rust_span="responses_provider_config"),
+    mapping(rust_span="validate_environment", python_frame=r"validate_environment$"),
+    mapping(rust_span="complete_url", python_frame=r"get_complete_url$"),
+    mapping(
+        rust_span="transform_request",
+        python_frame=r"(?<!AzureOpenAIResponsesAPIConfig\.)transform_responses_api_request$",
+    ),
+    mapping(
+        rust_span="execute_responses_provider_call",
+        python_frame=r"BaseLLMHTTPHandler\.(?:async_)?response_api_handler$",
+    ),
+    mapping(rust_span="http_request", python_frame=r"AsyncHTTPHandler\.post$|HTTPHandler\.post$"),
+    mapping(rust_span="transform_response", python_frame=r"transform_response_api_response$"),
+    mapping(span="python_logging_pre_call", python_frame=r"Logging\.pre_call$"),
+    mapping(span="python_success_callback", python_frame=r"Logging\.async_success_handler$|Logging\.success_handler$"),
+)
+
+STREAM_MAPPINGS: Final = (
+    mapping(
+        span="python_responses_stream_iterator",
+        python_frame=r"(?:Sync)?ResponsesAPIStreamingIterator\.__init__$",
+    ),
+    mapping(
+        span="python_responses_stream_next",
+        python_frame=r"(?:Sync)?ResponsesAPIStreamingIterator\.__a?next__$",
+    ),
+    mapping(span="python_responses_stream_transform", python_frame=r"transform_streaming_response$"),
+)
+
+FAILURE_MAPPINGS: Final = (
+    mapping(span="python_exception_mapping", python_frame=r"(?<!_)exception_type$"),
+    mapping(span="python_failure_callback", python_frame=r"Logging\.failure_handler$"),
+    mapping(span="python_async_failure_callback", python_frame=r"Logging\.async_failure_handler$"),
+)
+
+AZURE_MAPPINGS: Final = (
+    *COMMON_MAPPINGS,
+    mapping(
+        span="python_azure_transform_request",
+        python_frame=r"AzureOpenAIResponsesAPIConfig\.transform_responses_api_request$",
+    ),
+)
+
+BRIDGE_MAPPINGS: Final = (
+    mapping(span="python_responses", python_frame=r"responses/main\.py:\d+ a?responses$"),
+    mapping(
+        span="python_responses_chat_bridge", python_frame=r"ResponsesToCompletionBridgeHandler\.response_api_handler$"
+    ),
+    mapping(span="python_chat_completions", python_frame=r"main\.py:\d+ a?completion$"),
+    mapping(span="python_chat_transform_request", python_frame=r"AnthropicConfig\.transform_request$"),
+    mapping(span="python_logging_pre_call", python_frame=r"Logging\.pre_call$"),
+    mapping(rust_span="http_request", python_frame=r"AsyncHTTPHandler\.post$|HTTPHandler\.post$"),
+    mapping(span="python_chat_transform_response", python_frame=r"AnthropicConfig\.transform_response$"),
+    mapping(span="python_chat_to_responses", python_frame=r"LiteLLMResponsesTransformationHandler\..*response"),
+    mapping(span="python_success_callback", python_frame=r"Logging\.async_success_handler$|Logging\.success_handler$"),
+)
+
+
+def _native_fixture(engine: Engine, provider: str) -> RouteFixture:
+    model: Final = "gpt-5"
+    return RouteFixture(
+        kwargs={
+            "model": f"{provider}/{model}",
+            "input": "hello",
+            **({"body": {"model": model, "input": "hello"}} if engine == "rust" else {}),
+        },
+        provider_responses=(json_response(responses_body(model=model)),),
+    )
+
+
+def _openai_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    return _native_fixture(engine, "openai")
+
+
+def _azure_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _native_fixture(engine, "azure")
+    return fixture.derive(kwargs={"api_version": "2025-04-01-preview"})
+
+
+def _openai_stream_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _openai_fixture(engine, _base_url)
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(sse_response(responses_stream_events()),),
+        consume_stream=True,
+    )
+
+
+def _provider_error_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _openai_fixture(engine, _base_url)
+    return fixture.derive(
+        provider_responses=(
+            json_response({"error": {"message": "bad request", "type": "invalid_request_error"}}, status=400),
+        ),
+        expected_failure=True,
+    )
+
+
+def _stream_failed_fixture(engine: Engine, base_url: str) -> RouteFixture:
+    fixture: Final = _openai_fixture(engine, base_url)
+    failed_response: Final[dict[str, object]] = {
+        **responses_body(),
+        "status": "failed",
+        "output": [],
+        "error": {"message": "stream failed", "type": "server_error", "code": "server_error"},
+    }
+    events: Final = (
+        (
+            "response.created",
+            {"type": "response.created", "response": {**failed_response, "status": "in_progress", "error": None}},
+        ),
+        ("response.failed", {"type": "response.failed", "response": failed_response}),
+    )
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(sse_response(events),),
+        expected_failure=True,
+        consume_stream=True,
+    )
+
+
+def _anthropic_bridge_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    return RouteFixture(
+        kwargs={
+            "model": "anthropic/claude-sonnet-5",
+            "input": "hello",
+            "max_output_tokens": 16,
+            **({"body": {"model": "claude-sonnet-5", "input": "hello"}} if engine == "rust" else {}),
+        },
+        provider_responses=(json_response(anthropic_response_body()),),
+    )
+
+
+def _anthropic_bridge_stream_fixture(engine: Engine, _base_url: str) -> RouteFixture:
+    fixture: Final = _anthropic_bridge_fixture(engine, _base_url)
+    return fixture.derive(
+        kwargs={"stream": True},
+        provider_responses=(sse_response(anthropic_stream_events()),),
+        consume_stream=True,
+    )
+
+
+SPEC: Final = RouteSpec("responses", ("responses", "aresponses"), None, _openai_fixture)
+TRACE_SUITE: Final = TraceSuite(
+    route=SPEC,
+    scenarios=(
+        TraceScenario(name="sync-openai", fixture=_openai_fixture, mappings=COMMON_MAPPINGS, asynchronous=False),
+        TraceScenario(name="async-openai", fixture=_openai_fixture, mappings=COMMON_MAPPINGS, asynchronous=True),
+        TraceScenario(
+            name="sync-openai-stream",
+            fixture=_openai_stream_fixture,
+            mappings=(*COMMON_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=False,
+        ),
+        TraceScenario(
+            name="async-openai-stream",
+            fixture=_openai_stream_fixture,
+            mappings=(*COMMON_MAPPINGS, *STREAM_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-openai-provider-error",
+            fixture=_provider_error_fixture,
+            mappings=(*COMMON_MAPPINGS, *FAILURE_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-openai-stream-failed",
+            fixture=_stream_failed_fixture,
+            mappings=(*COMMON_MAPPINGS, *STREAM_MAPPINGS, *FAILURE_MAPPINGS),
+            asynchronous=True,
+        ),
+        TraceScenario(name="async-azure", fixture=_azure_fixture, mappings=AZURE_MAPPINGS, asynchronous=True),
+        TraceScenario(
+            name="async-anthropic-chat-bridge",
+            fixture=_anthropic_bridge_fixture,
+            mappings=BRIDGE_MAPPINGS,
+            asynchronous=True,
+        ),
+        TraceScenario(
+            name="async-anthropic-chat-bridge-stream",
+            fixture=_anthropic_bridge_stream_fixture,
+            mappings=(
+                *BRIDGE_MAPPINGS,
+                mapping(span="python_chat_stream_wrapper", python_frame=r"CustomStreamWrapper\.__init__$"),
+                mapping(span="python_chat_stream_next", python_frame=r"CustomStreamWrapper\.__anext__$"),
+                mapping(
+                    span="python_responses_bridge_stream_iterator",
+                    python_frame=r"LiteLLMCompletionStreamingIterator\.__init__$|LiteLLMCompletionStreamingIterator\.__anext__$",
+                ),
+            ),
+            asynchronous=True,
+        ),
+    ),
+)

tests/rust-python-harness/strategies/trace_parity/sdk/test_core_scenario_matrix.py

@@ -0,0 +1,69 @@
+from __future__ import annotations
+
+from importlib import import_module
+from typing import Final, cast
+
+from ..models import TraceSuite
+
+
+def _suite(module: str) -> TraceSuite:
+    loaded: Final = import_module(module)
+    candidate: Final = cast(object, getattr(loaded, "TRACE_SUITE"))
+    assert isinstance(candidate, TraceSuite)
+    return candidate
+
+
+def test_core_sdk_scenario_matrix_keeps_distinct_migration_paths() -> None:
+    chat: Final = _suite("tests.rust-python-harness.strategies.trace_parity.sdk.chat_completions.case")
+    messages: Final = _suite("tests.rust-python-harness.strategies.trace_parity.sdk.messages.case")
+    ocr: Final = _suite("tests.rust-python-harness.strategies.trace_parity.sdk.ocr.case")
+    responses: Final = _suite("tests.rust-python-harness.strategies.trace_parity.sdk.responses.case")
+
+    assert {(scenario.name, scenario.asynchronous) for scenario in chat.scenarios} >= {
+        ("sync-anthropic", False),
+        ("async-anthropic", True),
+        ("sync-anthropic-stream", False),
+        ("async-anthropic-stream", True),
+        ("async-anthropic-provider-error", True),
+        ("async-anthropic-stream-error", True),
+        ("sync-bedrock", False),
+        ("async-bedrock", True),
+        ("sync-bedrock-event-stream", False),
+        ("async-bedrock-event-stream", True),
+    }
+    assert {(scenario.name, scenario.asynchronous) for scenario in messages.scenarios} >= {
+        ("async-anthropic-stream", True),
+        ("async-azure-ai-stream", True),
+        ("async-bedrock-event-stream", True),
+        ("async-bedrock-event-stream-error", True),
+        ("async-bedrock-invalid-thinking-retry", True),
+        ("sync-unsupported", False),
+    }
+    assert {(scenario.name, scenario.asynchronous) for scenario in ocr.scenarios} >= {
+        ("async-cohere", True),
+        ("sync-public-rust-dispatch", False),
+        ("async-public-rust-dispatch", True),
+    }
+    assert {(scenario.name, scenario.asynchronous) for scenario in responses.scenarios} >= {
+        ("sync-openai", False),
+        ("async-openai", True),
+        ("sync-openai-stream", False),
+        ("async-openai-stream", True),
+        ("async-openai-provider-error", True),
+        ("async-openai-stream-failed", True),
+        ("async-azure", True),
+        ("async-anthropic-chat-bridge", True),
+        ("async-anthropic-chat-bridge-stream", True),
+    }
+
+
+def test_core_gateway_matrix_keeps_downstream_streams_separate() -> None:
+    modules: Final = (
+        "tests.rust-python-harness.strategies.trace_parity.gateway.chat_completions.case",
+        "tests.rust-python-harness.strategies.trace_parity.gateway.messages.case",
+        "tests.rust-python-harness.strategies.trace_parity.gateway.responses.case",
+    )
+
+    for module in modules:
+        suite = _suite(module)
+        assert any("downstream-stream" in scenario.name for scenario in suite.scenarios)

tests/rust-python-harness/strategies/trace_parity/sdk/transcription/case.py

@@ -92,11 +92,16 @@ TRACE_SUITE: Final = TraceSuite(
     route=SPEC,
     scenarios=(
         TraceScenario(
-            name="bedrock",
+            name="sync-bedrock",
             fixture=_fixture,
-            mappings=MAPPINGS,
-            sync_mappings=SYNC_MAPPINGS,
-            async_mappings=ASYNC_MAPPINGS,
+            mappings=SYNC_MAPPINGS,
+            asynchronous=False,
+        ),
+        TraceScenario(
+            name="async-bedrock",
+            fixture=_fixture,
+            mappings=ASYNC_MAPPINGS,
+            asynchronous=True,
         ),
     ),
 )

tests/rust-python-harness/strategies/trace_parity/test_reporting.py

@@ -1,58 +1,46 @@
 from __future__ import annotations
 
-from collections.abc import Sequence
 from typing import Final, Literal
 
 import pytest
 
 from ...shared.reporting.models import CaseResult, Coverage, HarnessCase, ResultArtifact, RunStatus
 from ...shared.reporting.strategy import ModuleCaseSpec, NotImplementedCaseSpec
-from ...shared.tracing.steps import PipelineStep, TraceContract, TraceMapping, mapping
+from ...shared.tracing.steps import PipelineStep
 from . import reporting
-from .reporting import TRACE_COMPARISON_ARTIFACT, TraceComparisonArtifact, render_trace_results
-
-MAPPINGS: Final = (
-    mapping(rust_span="ocr", python_frame=r"ocr/main\.py:\d+ a?ocr$"),
-    mapping(rust_span="http_request", python_frame=r"AsyncHTTPHandler\.post$"),
-)
+from .reporting import TRACE_ARTIFACT, TraceArtifact, render_trace_results
 
 
-def _result(comparison: TraceComparisonArtifact) -> CaseResult:
+def _result(trace: TraceArtifact) -> CaseResult:
     case: Final = HarnessCase(
         strategy_id="trace_parity",
         strategy_label="Trace parity",
-        sdk_function=comparison.sdk_function,
+        sdk_function=trace.sdk_function,
         spec=ModuleCaseSpec(coverage=Coverage.PARTIAL, module="example"),
-        surface=comparison.surface,
+        surface=trace.surface,
     )
     result: Final = CaseResult(case=case)
-    nodeid: Final = f"trace:sdk:{comparison.sdk_function}:{comparison.scenario}:{comparison.mode}"
+    nodeid: Final = f"trace:{trace.surface}:{trace.sdk_function}:{trace.scenario}"
     result.collected.add(nodeid)
-    result.record(
-        nodeid,
-        RunStatus.PASSED,
-        artifacts=(ResultArtifact(TRACE_COMPARISON_ARTIFACT, comparison.model_dump_json()),),
-    )
+    result.record(nodeid, RunStatus.PASSED, artifacts=(ResultArtifact(TRACE_ARTIFACT, trace.model_dump_json()),))
     return result
 
 
-def _comparison(
+def _trace(
     python: tuple[PipelineStep, ...],
     rust: tuple[PipelineStep, ...],
     *,
-    mappings: Sequence[TraceMapping] = MAPPINGS,
     rust_error: str | None = None,
-) -> TraceComparisonArtifact:
-    return TraceComparisonArtifact.from_traces(
+    engine: Literal["python", "rust", "both"] = "both",
+    scenario: str = "sync-default",
+) -> TraceArtifact:
+    return TraceArtifact.from_traces(
+        engine=engine,
         surface="sdk",
         sdk_function="ocr",
-        scenario="default",
-        mode="sync",
-        mappings=mappings,
-        contract=TraceContract(),
+        scenario=scenario,
         python=python,
         rust=rust,
-        python_unmatched=796,
         rust_error=rust_error,
     )
 
@@ -67,107 +55,55 @@ def _events(*items: tuple[str, int, str | None]) -> tuple[PipelineStep, ...]:
     return tuple(steps)
 
 
-def test_renderer_shows_matching_python_and_rust_paths() -> None:
-    rust: Final = _events(("ocr", 0, None), ("http_request", 1, None))
+def test_renderer_prints_python_and_rust_traces_independently() -> None:
     python: Final = _events(
         ("ocr", 0, "ocr/main.py:88 aocr"),
-        ("http_request", 1, "http_handler.py:673 AsyncHTTPHandler.post"),
+        ("python_prepare", 1, "prep.py:1 python_prepare"),
     )
-
-    section: Final = render_trace_results((_result(_comparison(python, rust)),))[0]
-    report: Final = "\n\n".join(section.blocks)
-
-    assert section.title == "SDK trace comparisons"
-    assert "Case: ocr" in report
-    assert "PYTHON (2 steps)\n1 aocr  (ocr/main.py:88)\n2   AsyncHTTPHandler.post  (http_handler.py:673)" in report
-    assert "RUST (2 steps)\nocr  ->  1 aocr\n  http_request  ->  2 AsyncHTTPHandler.post" in report
-    assert "Mapping (identifier -> span)" not in report
-    assert "Trace: MATCH" in report
-    assert "Same steps, order, and nesting" in report
-    assert "Unseen mappings:" not in report
-
-
-def test_renderer_reports_mappings_that_matched_nothing() -> None:
-    events: Final = _events(("ocr", 0, None))
-
-    section: Final = render_trace_results((_result(_comparison(events, events)),))[0]
-    report: Final = "\n\n".join(section.blocks)
-
-    assert "Unseen mappings: http_request" in report
-    assert "Contract: FAIL" in report
-
-
-def test_renderer_numbers_repeated_span_occurrences() -> None:
-    mappings: Final = (MAPPINGS[0], MAPPINGS[1])
-    rust: Final = _events(("ocr", 0, None), ("http_request", 1, None), ("http_request", 1, None))
-    python: Final = _events(
-        ("ocr", 0, "ocr/main.py:88 aocr"),
-        ("http_request", 1, "http_handler.py:673 AsyncHTTPHandler.post"),
-        ("http_request", 1, "http_handler.py:673 AsyncHTTPHandler.post"),
-    )
-
-    report: Final = "\n\n".join(render_trace_results((_result(_comparison(python, rust, mappings=mappings)),))[0].blocks)
-
-    assert "http_request#2" in report
-
-
-def test_renderer_accepts_declared_engine_specific_steps() -> None:
-    mappings: Final = (
-        *MAPPINGS[:1],
-        mapping(span="python_prepare", python_frame=r"python_prepare$"),
-        mapping(rust_span="rust_prepare"),
-    )
-    python: Final = _events(("ocr", 0, None), ("python_prepare", 1, "prep.py:1 python_prepare"))
     rust: Final = _events(("ocr", 0, None), ("rust_prepare", 1, None))
 
-    section: Final = render_trace_results((_result(_comparison(python, rust, mappings=mappings)),))[0]
+    section: Final = render_trace_results((_result(_trace(python, rust)),))[0]
     report: Final = "\n\n".join(section.blocks)
 
-    assert "2   python_prepare  (prep.py:1)  [python only]" in report
-    assert "rust_prepare  ->  [rust only]" in report
-    assert "Trace: MATCH" in report
-    assert "Contract: PASS" in report
+    assert section.title == "SDK traces"
+    assert "PYTHON (2 steps)\n1 aocr  (ocr/main.py:88)\n2   python_prepare  (prep.py:1)" in report
+    assert "RUST (2 steps)\n1 ocr\n2   rust_prepare" in report
+    assert "python only" not in report
+    assert "rust only" not in report
+    assert " -> " not in report
+    assert "Trace: MATCH" not in report
+    assert "Trace: DRIFT" not in report
+    assert "Contract:" not in report
 
 
-def test_unavailable_check_reports_mode_from_nodeid() -> None:
-    case: Final = HarnessCase(
-        strategy_id="trace_parity",
-        strategy_label="Trace parity",
-        sdk_function="ocr",
-        spec=ModuleCaseSpec(coverage=Coverage.PARTIAL, module="example"),
-        surface="sdk",
-    )
-    result: Final = CaseResult(case=case)
-    result.collected.add("trace:sdk:ocr:default:sync")
-    result.record("trace:sdk:ocr:default:sync", RunStatus.ERROR)
+@pytest.mark.parametrize(
+    ("engine", "present", "absent"),
+    (("python", "PYTHON (1 steps)", "RUST"), ("rust", "RUST (1 steps)", "PYTHON")),
+)
+def test_renderer_prints_only_selected_engine(engine: Literal["python", "rust"], present: str, absent: str) -> None:
+    events: Final = _events(("ocr", 0, None))
 
-    section: Final = render_trace_results((result,))[0]
-    report: Final = "\n\n".join(section.blocks)
+    report: Final = "\n\n".join(render_trace_results((_result(_trace(events, events, engine=engine)),))[0].blocks)
 
-    assert "Case: ocr" in report
-    assert "Scenario: default / Mode: sync" in report
-    assert "Trace: NOT AVAILABLE\nTest outcome: error" in report
-    assert "unknown mode" not in report
+    assert present in report
+    assert absent not in report
 
 
 def test_renderer_keeps_collected_trace_when_one_engine_errors() -> None:
-    python: Final = _events(
-        ("ocr", 0, "ocr/main.py:88 aocr"),
-        ("http_request", 1, "http_handler.py:673 AsyncHTTPHandler.post"),
+    python: Final = _events(("ocr", 0, "ocr/main.py:88 aocr"))
+
+    report: Final = "\n\n".join(
+        render_trace_results(
+            (_result(_trace(python, (), rust_error="rust: native Rust bridge must include the trace-parity feature")),)
+        )[0].blocks
     )
 
-    section: Final = render_trace_results(
-        (_result(_comparison(python, (), rust_error="rust: native Rust bridge must include the trace-parity feature")),)
-    )[0]
-    report: Final = "\n\n".join(section.blocks)
-
-    assert "PYTHON (2 steps)\n1 aocr  (ocr/main.py:88)  [python only]" in report
+    assert "PYTHON (1 steps)\n1 aocr  (ocr/main.py:88)" in report
     assert "Rust error: rust: native Rust bridge must include the trace-parity feature" in report
     assert "hint: rebuild the native bridge with the trace-parity feature" in report
-    assert "Contract: FAIL" in report
 
 
-def test_renderer_groups_all_modes_under_one_case_header() -> None:
+def test_unavailable_trace_reports_scenario_from_nodeid() -> None:
     case: Final = HarnessCase(
         strategy_id="trace_parity",
         strategy_label="Trace parity",
@@ -176,76 +112,55 @@ def test_renderer_groups_all_modes_under_one_case_header() -> None:
         surface="sdk",
     )
     result: Final = CaseResult(case=case)
-    events: Final = _events(("ocr", 0, None))
-    modes: Final[tuple[Literal["sync", "async"], ...]] = ("sync", "async")
-    for mode in modes:
-        nodeid = f"trace:sdk:ocr:default:{mode}"
-        result.collected.add(nodeid)
-        comparison = TraceComparisonArtifact.from_traces(
-            surface="sdk",
-            sdk_function="ocr",
-            scenario="default",
-            mode=mode,
-            mappings=MAPPINGS,
-            contract=TraceContract(),
-            python=events,
-            rust=events,
-            python_unmatched=0,
-        )
-        result.record(
-            nodeid,
-            RunStatus.PASSED,
-            artifacts=(ResultArtifact(TRACE_COMPARISON_ARTIFACT, comparison.model_dump_json()),),
-        )
+    result.collected.add("trace:sdk:ocr:async-error")
+    result.record("trace:sdk:ocr:async-error", RunStatus.ERROR)
 
-    section: Final = render_trace_results((result,))[0]
+    report: Final = "\n\n".join(render_trace_results((result,))[0].blocks)
+
+    assert "Scenario: async-error" in report
+    assert "Trace: NOT AVAILABLE\nTest outcome: error" in report
+
+
+def test_renderer_groups_scenarios_under_one_case_header() -> None:
+    result: Final = _result(_trace(_events(("ocr", 0, None)), (), scenario="sync-default"))
+    async_trace: Final = _trace((), _events(("ocr", 0, None)), scenario="async-default")
+    nodeid: Final = "trace:sdk:ocr:async-default"
+    result.collected.add(nodeid)
+    result.record(nodeid, RunStatus.PASSED, artifacts=(ResultArtifact(TRACE_ARTIFACT, async_trace.model_dump_json()),))
+
+    report: Final = render_trace_results((result,))[0].blocks[0]
 
-    assert len(section.blocks) == 1
-    report: Final = section.blocks[0]
     assert report.count("Case: ocr") == 1
-    assert "Scenario: default / Mode: sync" in report
-    assert "Scenario: default / Mode: async" in report
+    assert "Scenario: sync-default" in report
+    assert "Scenario: async-default" in report
 
 
 def test_renderer_colors_every_trace_line_in_a_terminal(monkeypatch: pytest.MonkeyPatch) -> None:
-    rust: Final = _events(("ocr", 0, None), ("http_request", 1, None))
-    python: Final = _events(
-        ("ocr", 0, "ocr/main.py:88 aocr"),
-        ("http_request", 1, "http_handler.py:673 AsyncHTTPHandler.post"),
-    )
+    events: Final = _events(("ocr", 0, "ocr/main.py:88 aocr"))
     monkeypatch.setattr(reporting.sys.stdout, "isatty", lambda: True)
     monkeypatch.delenv("NO_COLOR", raising=False)
 
-    section: Final = render_trace_results((_result(_comparison(python, rust)),))[0]
-    report: Final = "\n\n".join(section.blocks)
+    report: Final = "\n\n".join(render_trace_results((_result(_trace(events, events)),))[0].blocks)
 
-    assert "\033[36mPYTHON\033[0m (2 steps)" in report
+    assert "\033[36mPYTHON\033[0m (1 steps)" in report
     assert "\033[36m1 aocr  (ocr/main.py:88)\033[0m" in report
-    assert "\033[33mRUST\033[0m (2 steps)" in report
-    assert "\033[33mocr\033[0m  ->  \033[36m1 aocr\033[0m" in report
-    assert "\033[33mhttp_request\033[0m  ->  \033[36m2 AsyncHTTPHandler.post\033[0m" in report
+    assert "\033[33mRUST\033[0m (1 steps)" in report
+    assert "\033[33m1 ocr\033[0m" in report
 
 
-def test_renderer_groups_cases_and_unavailable_entries_by_surface() -> None:
-    events: Final = _events(("ocr", 0, None))
-    gateway_results: Final = tuple(
-        CaseResult(
-            case=HarnessCase(
-                strategy_id="trace_parity",
-                strategy_label="Trace parity",
-                sdk_function=sdk_function,
-                spec=NotImplementedCaseSpec(reason=f"No {sdk_function} case is registered."),
-                surface="gateway",
-            ),
-            status=RunStatus.NOT_IMPLEMENTED,
-        )
-        for sdk_function in ("ocr", "messages")
+def test_renderer_groups_unavailable_entries_by_surface() -> None:
+    gateway_result: Final = CaseResult(
+        case=HarnessCase(
+            strategy_id="trace_parity",
+            strategy_label="Trace parity",
+            sdk_function="messages",
+            spec=NotImplementedCaseSpec(reason="No messages case is registered."),
+            surface="gateway",
+        ),
+        status=RunStatus.NOT_IMPLEMENTED,
     )
 
-    sections: Final = render_trace_results((_result(_comparison(events, events)), *gateway_results))
+    sections: Final = render_trace_results((_result(_trace((), ())), gateway_result))
 
-    assert tuple(section.title for section in sections) == ("SDK trace comparisons", "GATEWAY trace comparisons")
-    gateway_report: Final = "\n\n".join(sections[1].blocks)
-    assert gateway_report.count("Not implemented") == 1
-    assert "- ocr: No ocr case is registered." in gateway_report
-    assert "- messages: No messages case is registered." in gateway_report
+    assert tuple(section.title for section in sections) == ("SDK traces", "GATEWAY traces")
+    assert "- messages: No messages case is registered." in "\n\n".join(sections[1].blocks)

tests/rust-python-harness/strategies/trace_parity/test_runner.py

@@ -1,12 +1,23 @@
 from __future__ import annotations
 
-from typing import Final
+import importlib
+import os
+from pathlib import Path
+from types import SimpleNamespace
+from typing import Final, cast
+
+import pytest
+
+import litellm
 
 from ...shared.reporting.models import Coverage, HarnessCase, HarnessRun, RunStatus, SdkFunction, Surface
 from ...shared.reporting.strategy import ModuleCaseSpec
-from ...shared.tracing.steps import Engine
+from ...shared.tracing.profiler import FunctionTraceEvent
+from ...shared.tracing.steps import Engine, PipelineStep, mapping
 from .models import GatewayRouteSpec, RouteFixture, RouteSpec, TraceScenario, TraceSuite
-from .runner import run_trace_mode, scenario_nodeids, validate_trace_suite
+from .reporting import TraceArtifact
+from .runner import run_trace_cases, run_trace_scenario, runner_selection, scenario_nodeids, validate_trace_suite
+from .sdk.execution import SdkCall, collect_trace, execute_trace
 
 
 def _fixture(_engine: Engine, _base_url: str) -> RouteFixture:
@@ -27,46 +38,243 @@ def test_scenario_filtering_and_occurrence_node_ids() -> None:
     suite: Final = TraceSuite(
         route=RouteSpec("ocr", ("ocr", "aocr"), ("ocr", "aocr"), _fixture),
         scenarios=(
-            TraceScenario("one", _fixture, (), modes=("sync", "async")),
-            TraceScenario("two", _fixture, (), modes=("async",)),
+            TraceScenario("sync-one", _fixture, (), asynchronous=False),
+            TraceScenario("async-one", _fixture, (), asynchronous=True),
+            TraceScenario("async-two", _fixture, (), asynchronous=True),
         ),
     )
     case: Final = _case()
 
-    nodes: Final = scenario_nodeids(suite, case, frozenset({"two"}))
+    nodes: Final = scenario_nodeids(suite, case, frozenset({"async-two"}))
 
-    assert tuple(nodeid for _, _, nodeid in nodes) == ("trace:sdk:ocr:two:async",)
+    assert tuple(nodeid for _, nodeid in nodes) == ("trace:sdk:ocr:async-two",)
+
+
+def test_python_engine_is_separate_from_scenario_selection() -> None:
+    assert runner_selection(("mistral", "--engine=python")) == (frozenset({"mistral"}), "python")
+
+
+def test_python_engine_skips_native_bridge(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
+    runner: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.runner")
+    case: Final = _case()
+    selected: list[tuple[frozenset[str], str]] = []
+
+    def reject_bridge(_repo_root: Path) -> str | None:
+        raise AssertionError("Python-only tracing must not inspect or build the native bridge")
+
+    def capture_case(
+        _run: HarnessRun,
+        _case: HarnessCase,
+        scenarios: frozenset[str],
+        _on_update: object,
+        engine: str,
+    ) -> None:
+        selected.append((scenarios, engine))
+
+    monkeypatch.setattr(runner, "ensure_trace_bridge", reject_bridge)
+    monkeypatch.setattr(runner, "_run_case", capture_case)
+
+    exit_code, _ = run_trace_cases((case,), tmp_path, lambda _: None, ("mistral", "--engine=python"))
+
+    assert exit_code == 0
+    assert selected == [(frozenset({"mistral"}), "python")]
+
+
+def test_python_trace_preserves_native_ocr_dispatch_setting(monkeypatch: pytest.MonkeyPatch) -> None:
+    execution: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.sdk.execution")
+    route: Final = RouteSpec("ocr", ("ocr", "aocr"), ("ocr", "aocr"), _fixture)
+    observed: list[str | None] = []
+
+    def collect(
+        _function: SdkCall,
+        _fixture: RouteFixture,
+        _engine: Engine,
+        *,
+        asynchronous: bool,
+    ) -> SimpleNamespace:
+        observed.append(os.environ.get("LITELLM_RUST"))
+        return SimpleNamespace(
+            events=(FunctionTraceEvent(0, None, "aocr" if asynchronous else "ocr"),),
+            error=None,
+        )
+
+    monkeypatch.setattr(execution, "_collect", collect)
+
+    monkeypatch.setenv("LITELLM_RUST", "0")
+    collect_trace(route, "python", asynchronous=False)
+    monkeypatch.setenv("LITELLM_RUST", "1")
+    collect_trace(route, "python", asynchronous=True)
+
+    assert observed == ["0", "1"]
+    assert os.environ["LITELLM_RUST"] == "1"
+
+
+def test_expected_provider_failure_omits_feedback_banner(
+    capsys: pytest.CaptureFixture[str], monkeypatch: pytest.MonkeyPatch
+) -> None:
+    loaded: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.sdk.responses.case")
+    suite: Final = cast(TraceSuite, loaded.TRACE_SUITE)
+    scenario: Final = next(item for item in suite.scenarios if item.name == "async-openai-provider-error")
+    monkeypatch.setattr(litellm, "suppress_debug_info", False)
+    assert isinstance(suite.route, RouteSpec)
+
+    result: Final = execute_trace(suite.route, scenario, "sdk", engine="python")
+
+    assert result.python_error is None
+    assert "Give Feedback / Get Help" not in capsys.readouterr().out
+    assert litellm.suppress_debug_info is False
+
+
+@pytest.mark.parametrize("asynchronous", (False, True))
+def test_vertex_trace_keeps_unmapped_helpers_and_parents(asynchronous: bool) -> None:
+    loaded: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.sdk.ocr.case")
+    suite: Final = cast(TraceSuite, loaded.TRACE_SUITE)
+    name: Final = f"{'async' if asynchronous else 'sync'}-vertex-deepseek"
+    scenario: Final = next(item for item in suite.scenarios if item.name == name)
+    assert isinstance(suite.route, RouteSpec)
+
+    trace: Final = execute_trace(suite.route, scenario, "sdk", engine="python")
+
+    assert trace.python_error is None
+    url: Final = next(
+        event for event in trace.python if event.raw.endswith(" VertexAIDeepSeekOCRConfig.get_complete_url")
+    )
+    project: Final = next(
+        event for event in trace.python if event.raw.endswith(" VertexBase.safe_get_vertex_ai_project")
+    )
+    location: Final = next(
+        event for event in trace.python if event.raw.endswith(" VertexBase.safe_get_vertex_ai_location")
+    )
+    assert project.parent_id == location.parent_id == url.id
+    assert not any(event.raw.endswith(" VertexBase.get_access_token") for event in trace.python)
+
+
+@pytest.mark.parametrize("asynchronous", (False, True))
+def test_vertex_credentials_trace_runs_real_auth_helpers(asynchronous: bool, monkeypatch: pytest.MonkeyPatch) -> None:
+    loaded: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.sdk.ocr.case")
+    suite: Final = cast(TraceSuite, loaded.TRACE_SUITE)
+    name: Final = f"{'async' if asynchronous else 'sync'}-vertex-deepseek-credentials"
+    scenario: Final = next(item for item in suite.scenarios if item.name == name)
+    monkeypatch.setenv("VERTEXAI_CREDENTIALS", "original-credentials")
+    monkeypatch.setenv("VERTEX_AI_API_KEY", "original-api-key")
+    assert isinstance(suite.route, RouteSpec)
+
+    trace: Final = execute_trace(suite.route, scenario, "sdk", engine="python")
+
+    assert trace.python_error is None
+    validate: Final = next(
+        event for event in trace.python if event.raw.endswith(" VertexAIDeepSeekOCRConfig.validate_environment")
+    )
+    helpers: Final = (
+        "VertexBase.safe_get_vertex_ai_project",
+        "VertexBase.safe_get_vertex_ai_credentials",
+        "VertexBase.get_access_token",
+    )
+    assert tuple(event.raw.split(" ", 1)[1] for event in trace.python if event.parent_id == validate.id) == helpers
+    token: Final = next(event for event in trace.python if event.raw.endswith(" VertexBase.get_access_token"))
+    load: Final = next(event for event in trace.python if event.raw.endswith(" VertexBase.load_auth"))
+    refresh: Final = next(event for event in trace.python if event.raw.endswith(" VertexBase.refresh_auth"))
+    assert load.parent_id == token.id
+    assert refresh.parent_id == load.id
+    assert os.environ["VERTEXAI_CREDENTIALS"] == "original-credentials"
+    assert os.environ["VERTEX_AI_API_KEY"] == "original-api-key"
+
+
+def test_gateway_trace_keeps_calls_outside_scenario_mappings(monkeypatch: pytest.MonkeyPatch) -> None:
+    execution: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.gateway.execution")
+    events: Final = (
+        FunctionTraceEvent(0, None, "route.py:1 entry"),
+        FunctionTraceEvent(1, 0, "auth.py:2 authenticate"),
+        FunctionTraceEvent(2, 1, "auth.py:3 credentials"),
+    )
+    scenario: Final = TraceScenario(
+        "async-gateway",
+        _fixture,
+        (mapping(rust_span="entry", python_frame=r" entry$"),),
+        asynchronous=True,
+    )
+    monkeypatch.setattr(execution, "_collect", lambda *_args: events)
+
+    trace: Final = execution.execute_gateway_trace(GatewayRouteSpec("messages"), scenario, engine="python")
+
+    assert trace.python_error is None
+    assert tuple((event.id, event.parent_id, event.raw) for event in trace.python) == tuple(
+        (event.id, event.parent_id, event.raw) for event in events
+    )
+
+
+def test_default_trace_skips_unavailable_rust_sdk_entrypoint(monkeypatch: pytest.MonkeyPatch) -> None:
+    execution: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.sdk.execution")
+    route: Final = RouteSpec("responses", ("responses", "aresponses"), None, _fixture)
+    scenario: Final = TraceScenario("sync-openai", _fixture, (), asynchronous=False)
+    engines: list[Engine] = []
+
+    def collect(_route: RouteSpec, engine: Engine, *, asynchronous: bool) -> tuple[FunctionTraceEvent, ...]:
+        engines.append(engine)
+        return (FunctionTraceEvent(0, None, "responses"),)
+
+    monkeypatch.setattr(execution, "collect_trace", collect)
+
+    trace: Final = execution.execute_trace(route, scenario, "sdk")
+
+    assert engines == ["python"]
+    assert trace.engine == "python"
+    assert trace.rust_error is None
+
+
+def test_default_trace_skips_unavailable_rust_gateway_route(monkeypatch: pytest.MonkeyPatch) -> None:
+    execution: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.gateway.execution")
+    route: Final = GatewayRouteSpec("responses", rust_supported=False)
+    scenario: Final = TraceScenario("async-openai", _fixture, (), asynchronous=True)
+    engines: list[Engine] = []
+
+    def collect(_route: GatewayRouteSpec, _scenario: TraceScenario, engine: Engine) -> tuple[FunctionTraceEvent, ...]:
+        engines.append(engine)
+        return (FunctionTraceEvent(0, None, "responses"),)
+
+    monkeypatch.setattr(execution, "_collect", collect)
+
+    trace: Final = execution.execute_gateway_trace(route, scenario)
+
+    assert engines == ["python"]
+    assert trace.engine == "python"
+    assert trace.rust_error is None
 
 
 def test_scenario_validation_rejects_duplicate_and_unsafe_names() -> None:
     route: Final = RouteSpec("ocr", ("ocr", "aocr"), ("ocr", "aocr"), _fixture)
     duplicate: Final = TraceSuite(
         route=route,
-        scenarios=(TraceScenario("same", _fixture, ()), TraceScenario("same", _fixture, ())),
+        scenarios=(
+            TraceScenario("sync-same", _fixture, (), asynchronous=False),
+            TraceScenario("sync-same", _fixture, (), asynchronous=False),
+        ),
+    )
+    unsafe: Final = TraceSuite(
+        route=route, scenarios=(TraceScenario("sync-bad:name", _fixture, (), asynchronous=False),)
     )
-    unsafe: Final = TraceSuite(route=route, scenarios=(TraceScenario("bad:name", _fixture, ()),))
     case: Final = _case()
 
     assert validate_trace_suite(duplicate, case) is not None
     assert validate_trace_suite(unsafe, case) is not None
 
 
-def test_scenario_validation_rejects_invalid_modes_and_route_registration() -> None:
-    invalid_modes: Final = TraceSuite(
+def test_scenario_validation_rejects_invalid_names_and_route_registration() -> None:
+    invalid_name: Final = TraceSuite(
         route=RouteSpec("ocr", ("ocr", "aocr"), ("ocr", "aocr"), _fixture),
-        scenarios=(TraceScenario("invalid", _fixture, (), modes=("sync", "sync")),),
+        scenarios=(TraceScenario("bedrock", _fixture, (), asynchronous=True),),
     )
     wrong_function: Final = TraceSuite(
         route=RouteSpec("messages", ("create", "acreate"), ("messages", "amessages"), _fixture),
-        scenarios=(TraceScenario("one", _fixture, ()),),
+        scenarios=(TraceScenario("sync-one", _fixture, (), asynchronous=False),),
     )
     wrong_surface: Final = TraceSuite(
         route=GatewayRouteSpec("ocr"),
-        scenarios=(TraceScenario("one", _fixture, ()),),
+        scenarios=(TraceScenario("sync-one", _fixture, (), asynchronous=False),),
     )
     case: Final = _case()
 
-    assert "unique sync/async modes" in (validate_trace_suite(invalid_modes, case) or "")
+    assert "start with sync- or async-" in (validate_trace_suite(invalid_name, case) or "")
     assert "does not match case function" in (validate_trace_suite(wrong_function, case) or "")
     assert "must use RouteSpec" in (validate_trace_suite(wrong_surface, case) or "")
 
@@ -77,11 +285,35 @@ def test_invalid_route_dispatch_records_harness_error() -> None:
     result: Final = run.results[case.key]
     suite: Final = TraceSuite(
         route=GatewayRouteSpec("ocr"),
-        scenarios=(TraceScenario("one", _fixture, (), modes=("sync",)),),
+        scenarios=(TraceScenario("sync-one", _fixture, (), asynchronous=False),),
     )
-    nodeid: Final = "trace:sdk:ocr:one:sync"
+    nodeid: Final = "trace:sdk:ocr:sync-one"
 
-    run_trace_mode(run, result, suite, suite.scenarios[0], "sync", "sdk", nodeid, lambda _: None)
+    run_trace_scenario(run, result, suite, suite.scenarios[0], "sdk", nodeid, lambda _: None)
 
     assert result.outcomes[nodeid] is RunStatus.ERROR
     assert run.failures == [(nodeid, "gateway route cannot run on the sdk surface")]
+
+
+def test_different_python_and_rust_traces_pass(monkeypatch: pytest.MonkeyPatch) -> None:
+    runner: Final = importlib.import_module("tests.rust-python-harness.strategies.trace_parity.runner")
+    case: Final = _case()
+    run: Final = HarnessRun.from_cases((case,))
+    result: Final = run.results[case.key]
+    suite: Final = TraceSuite(
+        route=RouteSpec("ocr", ("ocr", "aocr"), ("ocr", "aocr"), _fixture),
+        scenarios=(TraceScenario("sync-one", _fixture, (), asynchronous=False),),
+    )
+    trace: Final = TraceArtifact.from_traces(
+        surface="sdk",
+        sdk_function="ocr",
+        scenario="sync-one",
+        python=(PipelineStep(0, None, "python_step", "python.py:1 python_step"),),
+        rust=(PipelineStep(0, None, "rust_step", "rust_step"),),
+    )
+    monkeypatch.setattr(runner, "_execute_scenario", lambda *_args: trace)
+
+    run_trace_scenario(run, result, suite, suite.scenarios[0], "sdk", "trace:sdk:ocr:sync-one", lambda _: None)
+
+    assert result.outcomes["trace:sdk:ocr:sync-one"] is RunStatus.PASSED
+    assert run.failures == []

tests/rust-python-harness/strategies/unit_tests_mapping/mapping_validator.py

@@ -38,30 +38,28 @@ def _trace_functions(
     python_functions: Final[dict[str, PythonFunctionIdentity]] = {}
     rust_functions: Final[dict[str, RustFunctionIdentity]] = {}
     for scenario in suite.scenarios:
-        for mode in scenario.modes:
-            route: Final = RouteSpec(
-                route=suite.route.route,
-                python_entrypoints=suite.route.python_entrypoints,
-                rust_entrypoints=suite.route.rust_entrypoints,
-                fixture=scenario.fixture,
-            )
-            python_trace: Final = collect_trace(route, "python", asynchronous=mode == "async")
-            rust_trace: Final = collect_trace(route, "rust", asynchronous=mode == "async")
-            if isinstance(python_trace, TraceExecutionFailure):
-                raise ValueError(f"Python trace discovery failed for {scenario.name}/{mode}: {python_trace.message}")
-            if isinstance(rust_trace, TraceExecutionFailure):
-                raise ValueError(f"Rust trace discovery failed for {scenario.name}/{mode}: {rust_trace.message}")
-            mappings: Final = scenario.mappings_for(mode)
-            python_projection: Final = pipeline_projection("python", python_trace, mappings)
-            rust_projection: Final = pipeline_projection("rust", rust_trace, mappings)
-            for step in python_projection.steps:
-                if step.span in spec.trace_spans:
-                    function: Final = PythonFunctionIdentity.from_trace(step.raw)
-                    python_functions[function.raw] = function
-            for step in rust_projection.steps:
-                if step.span in spec.trace_spans:
-                    function: Final = RustFunctionIdentity.from_trace(step.raw)
-                    rust_functions[step.raw] = function
+        route: Final = RouteSpec(
+            route=suite.route.route,
+            python_entrypoints=suite.route.python_entrypoints,
+            rust_entrypoints=suite.route.rust_entrypoints,
+            fixture=scenario.fixture,
+        )
+        python_trace: Final = collect_trace(route, "python", asynchronous=scenario.asynchronous)
+        rust_trace: Final = collect_trace(route, "rust", asynchronous=scenario.asynchronous)
+        if isinstance(python_trace, TraceExecutionFailure):
+            raise ValueError(f"Python trace discovery failed for {scenario.name}: {python_trace.message}")
+        if isinstance(rust_trace, TraceExecutionFailure):
+            raise ValueError(f"Rust trace discovery failed for {scenario.name}: {rust_trace.message}")
+        python_projection: Final = pipeline_projection("python", python_trace, scenario.mappings)
+        rust_projection: Final = pipeline_projection("rust", rust_trace, scenario.mappings)
+        for step in python_projection.steps:
+            if step.span in spec.trace_spans:
+                function: Final = PythonFunctionIdentity.from_trace(step.raw)
+                python_functions[function.raw] = function
+        for step in rust_projection.steps:
+            if step.span in spec.trace_spans:
+                function: Final = RustFunctionIdentity.from_trace(step.raw)
+                rust_functions[step.raw] = function
     if not python_functions or not rust_functions:
         raise ValueError(f"Python trace discovery found no functions for spans: {', '.join(spec.trace_spans)}")
     return (