Why: The runtime could only speak OpenAI chat completions, so thinking levels, images, and the other vendor wires had nowhere to go.
Evidence: go test -count=1 ./runtime/llm/
Impact: Existing chat-completions calls stay the same unless a thinking level or image is set. Overflow errors are not retried.
Refs: feature/pi-headless N2
Co-authored-by: Cursor <cursoragent@cursor.com>