When json_schema response_format is sent to models that do not natively
support Structured Output (e.g. DeepSeek/Ollama/local LLMs via
openai-compatible-* providers), they often return empty or malformed
content.
Detect response_format.type === "json_schema", inject the schema into the
system prompt, and downgrade response_format to json_object so Structured
Output works transparently across openai-compatible providers.
Gated to provider.startsWith("openai-compatible-") so providers with
native Structured Output support are not downgraded.
Co-authored-by: Cursor <cursoragent@cursor.com>
f3176b4b23