Qwen3-8B (from the BFCL/AppWorld no-rethink SFT0 base) further SFT'd to learn
when to invoke a fresh-context "rethink" review during AppWorld agent
trajectories. Each supervised target is a decision chain-of-thought followed by
a one-line RETHINK: GOAL=...; CANDIDATE=...; EVIDENCE=...; RISK=... request;
the trajectory prefix before the trigger is masked out of the loss. Mixed 1:1
with main-agent replay to preserve base capability.
