Audit finding: value_guidance defaulted OFF, and it gated value-function TRAINING — so
by default the VF never trained, conditioning ascent + the chain sampler's embed_guidance
were permanently inert, and a user who ran many gens with it off then enabled it started
from zero (no accumulated learning).
Fix decouples learning from application:
- The VF now ALWAYS trains in the background on rated gens (cheap: small MLP, 20 steps,
no diffusion calls) whenever there's a rated previous run + refinement key. The reward
asset accumulates regardless of the toggle.
- value_guidance now controls only APPLICATION of the learned direction (output ascent +
search), via a new apply= param on _v2_ascend_conditioning. Default ON.
- Defaults flipped to True: refine_v2 signature, Studio settings read, JS default +
migration. Studio toggle relabeled 'Apply value guidance' with corrected help (training
always on; applies after 10+ ratings; off = strict prompt fidelity, learning still
accumulates). Fixed stale '5+ ratings' text (MIN_SAMPLES is 10).
Side effect: embed_guidance (chain sampler) now has a trained VF available by default.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
