Some OpenAI-compatible clients (Open WebUI, LobeChat, etc.) send
message content as an array of typed parts instead of a plain string:
[{"type": "text", "text": "hello"}]
The agent pipeline expects strings, so these array payloads caused
silent failures or empty messages.
Add _normalize_chat_content() with defensive limits (recursion depth,
list size, output length) and apply it to both the Chat Completions
and Responses API endpoints. The Responses path had inline
normalization that only handled input_text/output_text — the shared
function also handles the standard 'text' type.
Salvaged from PR #7980 (ikelvingo) — only the content normalization;
the SSE and Weixin changes in that PR were regressions and are not
included.
Co-authored-by: ikelvingo <ikelvingo@users.noreply.github.com>
