fix: await raw-JSON streaming error upsert so it persists to chat history (open-webui#27074)

When an upstream provider streams a raw JSON error payload without the SSE
`data:` prefix, the streaming handler parses it and attempts to persist it
to the assistant message via Chats.upsert_message_to_chat_by_id_and_message_id.
That coroutine was created without `await`, so the upsert was never executed:
the error was emitted to the client but dropped from the chat history.

Add the missing `await` so the raw-JSON fallback mirrors the normal streaming
error path (which already awaits). Also add a static regression test that fails
if any Chats.upsert_message_to_chat_by_id_and_message_id call site is left
un-awaited.

Refs https://github.com/open-webui/open-webui/issues/27074

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backend/open_webui/test/util/test_middleware_stream_error_persistence.py

@@ -0,0 +1,114 @@
+"""
+Regression tests for open-webui/open-webui#27074.
+
+Issue: when an upstream provider streams a raw JSON error payload *without*
+the SSE `data:` prefix, the streaming handler parses it and attempts to
+persist it to the assistant chat message via
+``Chats.upsert_message_to_chat_by_id_and_message_id``. That call is async, but
+the fallback path created the coroutine without ``await`` -- so the upsert was
+never executed. The error was emitted to the client but was NOT persisted to
+the chat history, leaving the assistant message without an error record.
+
+These tests guard against the regression by statically verifying that every
+``Chats.upsert_message_to_chat_by_id_and_message_id`` call site in
+``backend/open_webui/utils/middleware.py`` is actually awaited, and that the
+raw-JSON error fallback specifically persists the error to the DB.
+"""
+
+import ast
+from pathlib import Path
+
+MIDDLEWARE_PATH = (
+    Path(__file__).resolve().parents[2] / "utils" / "middleware.py"
+)
+UPSERT_NAME = "upsert_message_to_chat_by_id_and_message_id"
+
+
+def _load_tree():
+    assert MIDDLEWARE_PATH.exists(), (
+        f"Expected middleware source at {MIDDLEWARE_PATH}"
+    )
+    return ast.parse(MIDDLEWARE_PATH.read_text(encoding="utf-8"))
+
+
+def test_middleware_file_exists():
+    assert MIDDLEWARE_PATH.exists(), (
+        f"middleware.py not found at {MIDDLEWARE_PATH}"
+    )
+
+
+def _unawaited_upsert_calls(tree):
+    """Return a list of (lineno) for any upsert call that is NOT awaited.
+
+    A Call like ``Chats.upsert_message_to_chat_by_id_and_message_id(...)`` is
+    considered awaited only when its immediate parent in the AST is an
+    ``ast.Await`` node.  We map every node to its parent so we can inspect the
+    parent of each candidate Call.
+    """
+    parent_of = {}
+    for node in ast.walk(tree):
+        for child in ast.iter_child_nodes(node):
+            parent_of[child] = node
+
+    bad = []
+    for node in ast.walk(tree):
+        if not isinstance(node, ast.Call):
+            continue
+        func = node.func
+        if (
+            isinstance(func, ast.Attribute)
+            and func.attr == UPSERT_NAME
+            and isinstance(func.value, ast.Name)
+            and func.value.id == "Chats"
+        ):
+            if not isinstance(parent_of.get(node), ast.Await):
+                bad.append(node.lineno)
+    return bad
+
+
+def test_all_upsert_calls_are_awaited():
+    tree = _load_tree()
+    bad = _unawaited_upsert_calls(tree)
+    assert not bad, (
+        f"Found async upsert calls that are NOT awaited "
+        f"(missing `await Chats.{UPSERT_NAME}(...)`) at line(s): {bad}. "
+        f"These create coroutines that are never executed, so the error "
+        f"payload is dropped and never persisted to chat history."
+    )
+
+
+def test_raw_json_error_fallback_persists_error():
+    """
+    The raw-JSON streaming error fallback (a JSON line streamed without the
+    `data:` SSE prefix that carries an `error` key) must persist that error to
+    the assistant message via an awaited upsert, mirroring the normal streaming
+    error path. Confirm the fallback block awaits the upsert.
+    """
+    tree = _load_tree()
+    source = MIDDLEWARE_PATH.read_text(encoding="utf-8")
+
+    # Locate the raw-JSON fallback block: it parses a non-`data:` line as JSON
+    # and reads `error` from it.
+    fallback_block = None
+    for node in ast.walk(tree):
+        if isinstance(node, ast.If):
+            snippet = ast.get_source_segment(source, node) or ""
+            if "raw_obj" in snippet and "error" in snippet and "json.loads" in snippet:
+                fallback_block = snippet
+                break
+
+    assert fallback_block is not None, (
+        "Could not locate the raw-JSON streaming error fallback block in "
+        "middleware.py. The persistence path for #27074 may have moved."
+    )
+
+    # The fallback must perform an awaited upsert that writes
+    # {'error': {'content': ...}} to the chat message.
+    assert "await Chats.upsert_message_to_chat_by_id_and_message_id" in fallback_block, (
+        "The raw-JSON error fallback does not AWAIT the upsert that persists "
+        "the error to chat history. The coroutine will be dropped (open-webui#27074)."
+    )
+    assert "'error': {'content': raw_error}" in fallback_block, (
+        "The raw-JSON error fallback does not persist the parsed raw error "
+        "payload to the assistant message."
+    )

backend/open_webui/utils/middleware.py

@@ -4104,7 +4104,7 @@ async def streaming_chat_response_handler(response, ctx):
                                 raw_error = raw_obj.get('error') if isinstance(raw_obj, dict) else None
                                 if raw_error:
                                     try:
-                                        Chats.upsert_message_to_chat_by_id_and_message_id(
+                                        await Chats.upsert_message_to_chat_by_id_and_message_id(
                                             metadata['chat_id'],
                                             metadata['message_id'],
                                             {