Why: the direct chat path needs one shared loop for deliverable checks, tool pairing, reminders, and truncated replies, while squad callers keep today's behavior when the new fields stay unset.
Evidence: go test ./... in agent-native passed, including Stop cap, BeforeTool pairing, reminders absent from the session, repeat-guard cap, length continuation, and zero-value loop tests.
Impact: runtime.Config and llm.Event grow optional fields; AgentSession.Prompt copies them through. Squad sessions that leave them zero are unchanged.
Refs: feature/agent-harness-p1
Co-authored-by: Cursor <cursoragent@cursor.com>
Why: Steering hooks existed on the loop but nothing owned the queues, abort, or a model change during a run.
Evidence: go test -count=1 ./runtime/
Impact: Run still emits the existing event names. message_start, tool_execution_update, and agent_settled are added beside them.
Refs: feature/pi-headless N3
Co-authored-by: Cursor <cursoragent@cursor.com>