diff --git a/litellm/proxy/anthropic_endpoints/streaming_model_restamp.py b/litellm/proxy/anthropic_endpoints/streaming_model_restamp.py
new file mode 100644
index 00000000000..7da5e5099fc
--- /dev/null
+++ b/litellm/proxy/anthropic_endpoints/streaming_model_restamp.py
@@ -0,0 +1,174 @@
+"""
+Restamp the public ``model`` on the Anthropic Messages ``message_start`` event, the only
+stream event carrying a model, so streamed responses report the requested model like
+non-streaming ones do.
+
+Chunks reach the serializer either as already-encoded SSE frames (``bytes``/``str``, the
+provider passthrough path) or as event dicts (fake-stream and agentic paths).
+"""
+
+import json
+import re
+from collections.abc import Mapping
+from typing import Final
+
+from pydantic import TypeAdapter, ValidationError
+
+_MESSAGE_START_EVENT: Final = "message_start"
+_MESSAGE_START_MARKER: Final = b"message_start"
+_SSE_DATA_FIELD: Final = "data:"
+_SSE_FRAME_END_PATTERN: Final = re.compile(rb"\r\n\r\n|\r\r|\n\n")
+_MAX_HELD_BYTES: Final = 65536
+_PING_MARKERS: Final = (b"event: ping", b'"type": "ping"', b'"type":"ping"')
+
+_EVENT_ADAPTER: Final = TypeAdapter(Mapping[str, object])
+
+
+def _restamped_event(event: Mapping[str, object], requested_model: str) -> Mapping[str, object] | None:
+    message: Final = event.get("message")
+    if event.get("type") != _MESSAGE_START_EVENT or not isinstance(message, dict):
+        return None
+    if message.get("model") == requested_model:
+        return None
+    return {**event, "message": {**message, "model": requested_model}}  # mutable-ok: SSE payload, re-serialized as is
+
+
+def _restamped_data_line(line: str, requested_model: str) -> str | None:
+    stripped: Final = line.strip()
+    if not stripped.startswith(_SSE_DATA_FIELD):
+        return None
+    payload: Final = stripped[len(_SSE_DATA_FIELD) :].strip()
+    if not payload or payload == "[DONE]":
+        return None
+    try:
+        event: Final = _EVENT_ADAPTER.validate_json(payload)
+    except ValidationError:
+        return None
+    restamped: Final = _restamped_event(event, requested_model)
+    if restamped is None:
+        return None
+    terminator: Final = line[len(line.rstrip("\r\n")) :]
+    return f"data: {json.dumps(restamped, separators=(',', ':'))}{terminator}"
+
+
+def _restamped_frame(frame: str, requested_model: str) -> str | None:
+    lines: Final = frame.splitlines(keepends=True)
+    restamped: Final = tuple(_restamped_data_line(line, requested_model) for line in lines)
+    if all(line is None for line in restamped):
+        return None
+    return "".join(new if new is not None else old for new, old in zip(restamped, lines))
+
+
+def restamp_anthropic_stream_chunk_model(chunk: object, requested_model: str) -> object:
+    """
+    Return ``chunk`` with the ``message_start`` model replaced by ``requested_model``.
+
+    Chunks that carry no model are returned unchanged.
+    """
+    if isinstance(chunk, dict):
+        try:
+            event: Final = _EVENT_ADAPTER.validate_python(chunk)
+        except ValidationError:
+            return chunk
+        return _restamped_event(event, requested_model) or chunk
+
+    if isinstance(chunk, (bytes, bytearray)):
+        if _MESSAGE_START_EVENT.encode() not in chunk:
+            return chunk
+        restamped_bytes: Final = _restamped_frame(chunk.decode("utf-8", errors="ignore"), requested_model)
+        return chunk if restamped_bytes is None else restamped_bytes.encode("utf-8")
+
+    if isinstance(chunk, str):
+        if _MESSAGE_START_EVENT not in chunk:
+            return chunk
+        restamped_text: Final = _restamped_frame(chunk, requested_model)
+        return chunk if restamped_text is None else restamped_text
+
+    return chunk
+
+
+def _is_ping_frame(frame: bytes) -> bool:
+    return any(marker in frame for marker in _PING_MARKERS)
+
+
+class AnthropicStreamModelRestamper:
+    """
+    Per-stream restamper for the encoded passthrough path, where chunks are raw
+    transport reads: the ``message_start`` SSE frame can arrive split across
+    chunks or coalesced with later frames. Complete frames (``\\n\\n``,
+    ``\\r\\n\\r\\n``, or ``\\r\\r`` terminated) are emitted as their terminator
+    closes them and an incomplete tail is held until it completes, so the
+    restamp never misses a torn frame; ``flush`` returns whatever is still held
+    when the stream ends so no bytes are swallowed. Once ``message_start`` has
+    been handled, or the first real event proves the stream carries none, every
+    later chunk passes through untouched.
+    """
+
+    def __init__(self, requested_model: str) -> None:
+        self._requested_model: Final = requested_model
+        self._held = b""
+        self._armed = True
+
+    def process(self, chunk: object) -> object:
+        if not self._armed:
+            return chunk
+        if isinstance(chunk, (bytes, bytearray)):
+            return self._process_encoded(bytes(chunk))
+        if isinstance(chunk, str):
+            return self._process_encoded(chunk.encode("utf-8"))
+        restamped: Final = restamp_anthropic_stream_chunk_model(chunk, self._requested_model)
+        if isinstance(chunk, dict) and chunk.get("type") not in (None, "ping"):
+            self._armed = False
+        return restamped
+
+    def flush(self) -> bytes:
+        held: Final = self._held
+        self._held = b""
+        self._armed = False
+        if not held:
+            return b""
+        restamped: Final = restamp_anthropic_stream_chunk_model(held, self._requested_model)
+        return restamped if isinstance(restamped, bytes) else held
+
+    def _process_encoded(self, data: bytes) -> bytes:
+        combined: Final = self._held + data
+        boundaries: Final = tuple(match.end() for match in _SSE_FRAME_END_PATTERN.finditer(combined))
+        if not boundaries:
+            if len(combined) > _MAX_HELD_BYTES:
+                self._held = b""
+                self._armed = False
+                return combined
+            self._held = combined
+            return b""
+        emitted: Final = self._restamped_closed_block(combined[: boundaries[-1]])
+        tail: Final = combined[boundaries[-1] :]
+        if not self._armed:
+            self._held = b""
+            return emitted + tail
+        self._held = tail
+        return emitted
+
+    def _restamped_closed_block(self, closed: bytes) -> bytes:
+        boundaries: Final = tuple(match.end() for match in _SSE_FRAME_END_PATTERN.finditer(closed))
+        frames: Final = tuple(closed[start:end] for start, end in zip((0, *boundaries[:-1]), boundaries))
+        decider: Final = next(
+            (
+                index
+                for index, frame in enumerate(frames)
+                if _MESSAGE_START_MARKER in frame or (b"data:" in frame and not _is_ping_frame(frame))
+            ),
+            None,
+        )
+        if decider is None:
+            return closed
+        self._armed = False
+        if _MESSAGE_START_MARKER not in frames[decider]:
+            return closed
+        restamped_text: Final = _restamped_frame(
+            frames[decider].decode("utf-8", errors="ignore"), self._requested_model
+        )
+        if restamped_text is None:
+            return closed
+        return b"".join(
+            restamped_text.encode("utf-8") if index == decider else frame for index, frame in enumerate(frames)
+        )
diff --git a/litellm/proxy/common_request_processing.py b/litellm/proxy/common_request_processing.py
index 1d860b02875..05ddef822f1 100644
--- a/litellm/proxy/common_request_processing.py
+++ b/litellm/proxy/common_request_processing.py
@@ -176,6 +176,9 @@ if TYPE_CHECKING:
     ProxyConfig = _ProxyConfig
 else:
     ProxyConfig = Any
+from litellm.proxy.anthropic_endpoints.streaming_model_restamp import (
+    AnthropicStreamModelRestamper,
+)
 from litellm.proxy.litellm_pre_call_utils import (
     add_litellm_data_to_request,
     refresh_proxy_server_request_body_snapshot,
@@ -2490,6 +2493,9 @@ class ProxyBaseLLMRequestProcessing:
                             request_data=self.data,
                             proxy_logging_obj=proxy_logging_obj,
                             request=request,
+                            restamp_model=(
+                                None if _should_return_raw_model_name(self.data) else requested_model_from_client
+                            ),
                         )
                         return await create_response(
                             generator=wrap_sse_stream_with_keepalive_pings(
@@ -3442,6 +3448,16 @@ class ProxyBaseLLMRequestProcessing:
         else:
             return chunk
 
+    @staticmethod
+    def _sse_chunk_serializer(restamper: AnthropicStreamModelRestamper | None) -> StreamChunkSerializer:
+        if restamper is None:
+            return ProxyBaseLLMRequestProcessing.return_sse_chunk
+
+        def serialize(chunk: object) -> str:
+            return ProxyBaseLLMRequestProcessing.return_sse_chunk(restamper.process(chunk))
+
+        return serialize
+
     @staticmethod
     async def _finalize_streaming_generator_cleanup(
         request: Request | None,
@@ -3502,11 +3518,16 @@ class ProxyBaseLLMRequestProcessing:
         serialize_chunk: StreamChunkSerializer,
         serialize_error: StreamErrorSerializer,
         request: Request | None = None,
+        flush_tail: Callable[[], bytes] | None = None,
     ) -> AsyncGenerator[str, None]:
         """
         Shared streaming data generator: runs proxy iterator hook, per-chunk hook,
         cost injection, then yields chunks via serialize_chunk; on exception runs
         failure hook and yields via serialize_error. Use for SSE or NDJSON.
+
+        ``flush_tail`` runs once after the upstream iterator completes cleanly and
+        its non-empty result is yielded, so a serializer that buffers bytes across
+        chunks can emit anything still held at end of stream.
         """
         verbose_proxy_logger.debug("inside generator")
         # Resolve per-stream (not per-chunk) whether the heavy per-chunk path
@@ -3569,6 +3590,9 @@ class ProxyBaseLLMRequestProcessing:
                 # so it must not suppress that refund.
                 delivered_chunk = delivered_chunk or chunk != STREAM_SSE_KEEPALIVE_PING_BYTES
                 yield serialize_chunk(chunk)
+            held_tail: Final = flush_tail() if flush_tail is not None else b""
+            if held_tail:
+                yield serialize_chunk(held_tail)
             stream_completed = True
         except (asyncio.CancelledError, GeneratorExit):
             # Client disconnected mid-stream. CancelledError / GeneratorExit
@@ -3579,8 +3603,7 @@ class ProxyBaseLLMRequestProcessing:
             # billing and release exactly once. This is the outermost generator
             # Starlette closes on disconnect, so the nested iterator hook (which
             # only sees GeneratorExit on GC) cannot own the refund.
-            if not stream_completed:
-                client_disconnected = True
+            client_disconnected = not stream_completed
             if not delivered_chunk and not _withheld_provider_output(response):
                 from litellm.proxy.spend_tracking.budget_reservation import (
                     release_budget_reservation_on_cancel,
@@ -3634,6 +3657,7 @@ class ProxyBaseLLMRequestProcessing:
         request_data: dict,
         proxy_logging_obj: ProxyLogging,
         request: Request | None = None,
+        restamp_model: str | None = None,
     ) -> AsyncGenerator[str, None]:
         """
         Anthropic /messages and Google /generateContent streaming data generator require SSE events.
@@ -3642,17 +3666,23 @@ class ProxyBaseLLMRequestProcessing:
         SSE serializers directly (rather than re-wrapping it in another
         ``async for: yield`` trampoline), so a streamed chunk traverses one
         fewer async-generator layer / coroutine resume on the hot path.
+
+        ``restamp_model`` publishes that name on the Anthropic ``message_start``
+        event in place of the provider's model, matching what the non-streaming
+        response reports.
         """
+        restamper: Final = AnthropicStreamModelRestamper(restamp_model) if restamp_model else None
         return ProxyBaseLLMRequestProcessing.async_streaming_data_generator(
             response=response,
             user_api_key_dict=user_api_key_dict,
             request_data=request_data,
             proxy_logging_obj=proxy_logging_obj,
-            serialize_chunk=ProxyBaseLLMRequestProcessing.return_sse_chunk,
+            serialize_chunk=ProxyBaseLLMRequestProcessing._sse_chunk_serializer(restamper),
             serialize_error=lambda proxy_exc: (
                 f"{STREAM_SSE_DATA_PREFIX}{json.dumps({'error': proxy_exc.to_dict()})}\n\n"
             ),
             request=request,
+            flush_tail=None if restamper is None else restamper.flush,
         )
 
     @overload
diff --git a/tests/test_litellm/proxy/anthropic_endpoints/test_streaming_model_restamp.py b/tests/test_litellm/proxy/anthropic_endpoints/test_streaming_model_restamp.py
new file mode 100644
index 00000000000..b7bc670c7f8
--- /dev/null
+++ b/tests/test_litellm/proxy/anthropic_endpoints/test_streaming_model_restamp.py
@@ -0,0 +1,288 @@
+"""
+Tests for restamping the public model on Anthropic Messages streaming chunks.
+"""
+
+import json
+from unittest.mock import AsyncMock, MagicMock
+
+import pytest
+
+from litellm.proxy.anthropic_endpoints.streaming_model_restamp import (
+    AnthropicStreamModelRestamper,
+    restamp_anthropic_stream_chunk_model,
+)
+from litellm.proxy.common_request_processing import ProxyBaseLLMRequestProcessing
+
+
+def _message_start_frame(model: str, line_end: str = "\n") -> bytes:
+    payload = {
+        "type": "message_start",
+        "message": {"id": "msg_1", "type": "message", "role": "assistant", "model": model, "content": []},
+    }
+    return f"event: message_start{line_end}data: {json.dumps(payload)}{line_end}{line_end}".encode()
+
+
+def _proxy_logging_obj_streaming(frames: list[bytes]) -> MagicMock:
+    async def _iterator_hook(**_kwargs):
+        for frame in frames:
+            yield frame
+
+    proxy_logging_obj = MagicMock()
+    proxy_logging_obj.async_post_call_streaming_iterator_hook = _iterator_hook
+    proxy_logging_obj.async_post_call_streaming_hook = AsyncMock(side_effect=lambda **kwargs: kwargs["response"])
+    return proxy_logging_obj
+
+
+def _model_from_frame(frame: bytes | str) -> str:
+    text = frame.decode("utf-8") if isinstance(frame, bytes) else frame
+    data_line = next(line for line in text.split("\n") if line.startswith("data:"))
+    return json.loads(data_line[len("data:") :])["message"]["model"]
+
+
+def test_restamps_sse_bytes_frame():
+    restamped = restamp_anthropic_stream_chunk_model(
+        _message_start_frame("claude-haiku-4-5-20251001"), "claude-auto-1"
+    )
+
+    assert isinstance(restamped, bytes)
+    assert _model_from_frame(restamped) == "claude-auto-1"
+    assert b"event: message_start" in restamped
+
+
+def test_restamps_event_dict():
+    chunk = {"type": "message_start", "message": {"id": "msg_1", "model": "claude-sonnet-4-6"}}
+
+    restamped = restamp_anthropic_stream_chunk_model(chunk, "claude-auto-2")
+
+    assert restamped == {"type": "message_start", "message": {"id": "msg_1", "model": "claude-auto-2"}}
+    assert chunk["message"]["model"] == "claude-sonnet-4-6"
+
+
+@pytest.mark.parametrize(
+    "chunk",
+    [
+        b'event: content_block_delta\ndata: {"type":"content_block_delta","delta":{"text":"hi"}}\n\n',
+        {"type": "content_block_delta", "delta": {"text": "hi"}},
+        {"type": "message_start", "message": "not-a-dict"},
+        b"event: message_start\ndata: not-json\n\n",
+        b"data: [DONE]\n\n",
+    ],
+)
+def test_leaves_chunks_without_a_model_untouched(chunk):
+    assert restamp_anthropic_stream_chunk_model(chunk, "claude-auto-1") == chunk
+
+
+@pytest.mark.asyncio
+async def test_sse_generator_publishes_requested_model_on_message_start():
+    """The message_start event reports the requested model, not the provider's."""
+    delta_frame = b'event: content_block_delta\ndata: {"type":"content_block_delta","delta":{"text":"hi"}}\n\n'
+    proxy_logging_obj = _proxy_logging_obj_streaming([_message_start_frame("claude-haiku-4-5-20251001"), delta_frame])
+
+    chunks = [
+        chunk
+        async for chunk in ProxyBaseLLMRequestProcessing.async_sse_data_generator(
+            response=MagicMock(),
+            user_api_key_dict=MagicMock(),
+            request_data={"model": "claude-auto-1"},
+            proxy_logging_obj=proxy_logging_obj,
+            restamp_model="claude-auto-1",
+        )
+    ]
+
+    assert _model_from_frame(chunks[0]) == "claude-auto-1"
+    assert chunks[1] == delta_frame
+
+
+@pytest.mark.asyncio
+async def test_sse_generator_keeps_provider_model_when_restamping_is_off():
+    proxy_logging_obj = _proxy_logging_obj_streaming([_message_start_frame("claude-haiku-4-5-20251001")])
+
+    chunks = [
+        chunk
+        async for chunk in ProxyBaseLLMRequestProcessing.async_sse_data_generator(
+            response=MagicMock(),
+            user_api_key_dict=MagicMock(),
+            request_data={"model": "claude-auto-1"},
+            proxy_logging_obj=proxy_logging_obj,
+        )
+    ]
+
+    assert _model_from_frame(chunks[0]) == "claude-haiku-4-5-20251001"
+
+
+def test_restamps_message_start_split_across_transport_chunks():
+    frame = _message_start_frame("claude-haiku-4-5-20251001")
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+
+    held = restamper.process(frame[:25])
+    emitted = restamper.process(frame[25:])
+
+    assert held == b""
+    assert isinstance(emitted, bytes)
+    assert _model_from_frame(emitted) == "claude-auto-1"
+
+
+def test_emits_coalesced_frames_with_only_message_start_rewritten():
+    delta = b'event: content_block_delta\ndata: {"type":"content_block_delta","delta":{"text":"hi"}}\n\n'
+    combined = _message_start_frame("claude-haiku-4-5-20251001") + delta
+
+    emitted = restamper_output = AnthropicStreamModelRestamper("claude-auto-1").process(combined)
+
+    assert isinstance(restamper_output, bytes)
+    assert _model_from_frame(emitted) == "claude-auto-1"
+    assert emitted.endswith(delta)
+
+
+def test_ping_frames_keep_the_restamper_armed():
+    ping = b'event: ping\ndata: {"type": "ping"}\n\n'
+    frame = _message_start_frame("claude-haiku-4-5-20251001")
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+
+    assert restamper.process(ping) == ping
+    reassembled = restamper.process(frame[:10])
+    reassembled += restamper.process(frame[10:])
+
+    assert _model_from_frame(reassembled) == "claude-auto-1"
+
+
+def test_first_non_ping_event_disarms_the_restamper():
+    delta = b'event: content_block_delta\ndata: {"type":"content_block_delta","delta":{"text":"hi"}}\n\n'
+    late_message_start = _message_start_frame("claude-haiku-4-5-20251001")
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+
+    assert restamper.process(delta) == delta
+    assert restamper.process(late_message_start) == late_message_start
+
+
+def test_oversized_unterminated_chunk_flushes_unmodified():
+    blob = b"data: " + b"x" * 70000
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+
+    assert restamper.process(blob) == blob
+    frame = _message_start_frame("claude-haiku-4-5-20251001")
+    assert restamper.process(frame) == frame
+
+
+def test_dict_message_start_disarms_after_restamp():
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+    first = restamper.process({"type": "message_start", "message": {"id": "msg_1", "model": "claude-sonnet-4-6"}})
+    second = {"type": "message_start", "message": {"id": "msg_2", "model": "claude-sonnet-4-6"}}
+
+    assert first == {"type": "message_start", "message": {"id": "msg_1", "model": "claude-auto-1"}}
+    assert restamper.process(second) == second
+
+
+@pytest.mark.asyncio
+async def test_sse_generator_restamps_message_start_split_across_chunks():
+    frame = _message_start_frame("claude-haiku-4-5-20251001")
+    proxy_logging_obj = _proxy_logging_obj_streaming([frame[:30], frame[30:]])
+
+    chunks = [
+        chunk
+        async for chunk in ProxyBaseLLMRequestProcessing.async_sse_data_generator(
+            response=MagicMock(),
+            user_api_key_dict=MagicMock(),
+            request_data={"model": "claude-auto-1"},
+            proxy_logging_obj=proxy_logging_obj,
+            restamp_model="claude-auto-1",
+        )
+    ]
+
+    joined = b"".join(chunk if isinstance(chunk, bytes) else chunk.encode("utf-8") for chunk in chunks)
+    assert _model_from_frame(joined) == "claude-auto-1"
+
+
+def test_restamps_crlf_terminated_message_start_frame():
+    frame = _message_start_frame("claude-haiku-4-5-20251001", line_end="\r\n")
+    delta = b'event: content_block_delta\r\ndata: {"type":"content_block_delta","delta":{"text":"hi"}}\r\n\r\n'
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+
+    emitted = restamper.process(frame)
+
+    assert isinstance(emitted, bytes)
+    assert _model_from_frame(emitted) == "claude-auto-1"
+    assert emitted.endswith(b"\r\n\r\n")
+    assert restamper.process(delta) == delta
+
+
+def test_restamps_cr_terminated_message_start_frame():
+    frame = _message_start_frame("claude-haiku-4-5-20251001", line_end="\r")
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+
+    emitted = restamper.process(frame)
+
+    assert isinstance(emitted, bytes)
+    assert b'"model":"claude-auto-1"' in emitted
+    assert emitted.endswith(b"\r\r")
+
+
+def test_restamps_crlf_message_start_split_across_transport_chunks():
+    frame = _message_start_frame("claude-haiku-4-5-20251001", line_end="\r\n")
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+
+    held = restamper.process(frame[:25])
+    emitted = restamper.process(frame[25:])
+
+    assert held == b""
+    assert isinstance(emitted, bytes)
+    assert _model_from_frame(emitted) == "claude-auto-1"
+
+
+def test_flush_returns_restamped_held_tail():
+    unterminated = _message_start_frame("claude-haiku-4-5-20251001")[:-2]
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+
+    assert restamper.process(unterminated) == b""
+    flushed = restamper.flush()
+
+    assert b'"model":"claude-auto-1"' in flushed
+    assert restamper.flush() == b""
+
+
+def test_flush_disarms_the_restamper():
+    restamper = AnthropicStreamModelRestamper("claude-auto-1")
+    frame = _message_start_frame("claude-haiku-4-5-20251001")
+
+    assert restamper.flush() == b""
+    assert restamper.process(frame) == frame
+
+
+@pytest.mark.asyncio
+async def test_sse_generator_flushes_held_tail_at_end_of_stream():
+    unterminated = _message_start_frame("claude-haiku-4-5-20251001")[:-2]
+    proxy_logging_obj = _proxy_logging_obj_streaming([unterminated])
+
+    chunks = [
+        chunk
+        async for chunk in ProxyBaseLLMRequestProcessing.async_sse_data_generator(
+            response=MagicMock(),
+            user_api_key_dict=MagicMock(),
+            request_data={"model": "claude-auto-1"},
+            proxy_logging_obj=proxy_logging_obj,
+            restamp_model="claude-auto-1",
+        )
+    ]
+
+    joined = b"".join(chunk if isinstance(chunk, bytes) else chunk.encode("utf-8") for chunk in chunks)
+    assert b'"model":"claude-auto-1"' in joined
+
+
+@pytest.mark.asyncio
+async def test_sse_generator_restamps_crlf_stream():
+    frame = _message_start_frame("claude-haiku-4-5-20251001", line_end="\r\n")
+    delta = b'event: content_block_delta\r\ndata: {"type":"content_block_delta","delta":{"text":"hi"}}\r\n\r\n'
+    proxy_logging_obj = _proxy_logging_obj_streaming([frame, delta])
+
+    chunks = [
+        chunk
+        async for chunk in ProxyBaseLLMRequestProcessing.async_sse_data_generator(
+            response=MagicMock(),
+            user_api_key_dict=MagicMock(),
+            request_data={"model": "claude-auto-1"},
+            proxy_logging_obj=proxy_logging_obj,
+            restamp_model="claude-auto-1",
+        )
+    ]
+
+    assert _model_from_frame(chunks[0]) == "claude-auto-1"
+    assert chunks[1] == delta