fix(proxy): import soundfile lazily in the transcribe logging handler (#51480)

* fix(proxy): import soundfile lazily in the transcribe logging handler

The messages streaming path imports the pass-through success handler, which
pulled in soundfile at module load. Installs without soundfile failed on
every Anthropic and Bedrock messages stream. Only media_file_seconds needs it

Fixes #45379

* test(vector_store): pin set_verbose off in the SDK fallback warning test

An ambient litellm.set_verbose=True adds a deprecation warning to the captured records, so the exact one-warning assertion failed depending on test order

---------

Co-authored-by: Joshua Valluru <326636767+joshua-berri@users.noreply.github.com>

litellm/proxy/pass_through_endpoints/llm_provider_handlers/transcribe_passthrough_logging_handler.py

@@ -13,7 +13,6 @@ from typing import IO, ClassVar, Final, Protocol, TypeAlias
 from urllib.parse import quote
 
 import httpx
-import soundfile
 from pydantic import ConfigDict, TypeAdapter, ValidationError
 from typing_extensions import ReadOnly, TypedDict
 
@@ -522,6 +521,8 @@ async def write_media_within_limit(response: httpx.Response, media_file: IO[byte
 
 
 def media_file_seconds(path: Path) -> float | None:
+    import soundfile
+
     try:
         with soundfile.SoundFile(str(path)) as audio:
             frames: Final = len(audio)

tests/unit/proxy/pass_through_endpoints/llm_provider_handlers/test_transcribe_passthrough_logging_handler.py

@@ -1,7 +1,9 @@
 import asyncio
+import importlib
 import io
 import json
 import struct
+import sys
 import wave
 from datetime import datetime
 from pathlib import Path
@@ -471,6 +473,21 @@ class TestMediaFileSeconds:
         assert media_file_seconds(media) is None
 
 
+def test_passthrough_logging_imports_without_soundfile_installed(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setitem(sys.modules, "soundfile", None)
+    for name in (
+        "litellm.proxy.pass_through_endpoints.llm_provider_handlers.transcribe_passthrough_logging_handler",
+        "litellm.proxy.pass_through_endpoints.success_handler",
+    ):
+        package, _, attribute = name.rpartition(".")
+        monkeypatch.setattr(sys.modules[package], attribute, sys.modules[name])
+        monkeypatch.delitem(sys.modules, name)
+
+    success_handler: Final = importlib.import_module("litellm.proxy.pass_through_endpoints.success_handler")
+
+    assert success_handler.PassThroughEndpointLogging is not PassThroughEndpointLogging
+
+
 class TestStartedTranscriptionJob:
     def test_reads_the_media_and_creation_time_from_the_start_response(self):
         started = started_transcription_job(