wassnameandClaude Opus 4.7
9ba7b818a9
Per-source cin (cin_s, cin_t) requires splitting each prompt's backward into student-only + teacher-only passes, which roughly doubles backward wall-time. With cin_s/cin_t empirically stable for 50 steps in #51 (cin_t ~0.37, cin_s ~0.18 with low variance), every-step is overkill. Add Config.cin_split_every: int = 1 (current behavior). Set >1 to compute cin_s/cin_t only every Nth step; combined single-backward on the others. cin_s/cin_t print as NaN on skipped steps. Projection + optimizer step unchanged (still uses combined grad). Default 1 preserves the current run cost; user can opt into 10 for ~half the backward time once the diagnostic is in steady state. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
projected_grpo
SVD-basis gradient projection vs RL reward hacking. Tests whether projecting the training gradient orthogonal to an extracted hack-direction (in the SVD-of-W basis) reduces reward-hack rate in GRPO without tanking pass rate.
Built on Ariahw, Engels & Nanda's rl-rewardhacking LeetCode benchmark. Method differs from concurrent work (Wu & Tang 2026, "Advantage Modification") by intervening at the gradient level rather than the advantage level.
See docs/spec.md, docs/brainstorm/extracted_prefs.md, and docs/papers/.
Quick start
uv sync
just fast-dev-run # tiny-random model, ~1-2 min, real pipeline end-to-end
just smoke-vanilla # vanilla pathway smoke
just smoke-projected # projected pathway smoke
just download-model # warm Qwen3-4B cache (full preset peaks ~73GB on 96GB)
just queue-full # queue extract + 3-seed vanilla + 3-seed projected sweep
See RESEARCH_JOURNAL.md for session-by-session findings,
including the 2026-05-23 grader-bug discovery that invalidated all prior gt=0
measurements and the move from Qwen3.5-2B to Qwen3-4B (reference substrate).
Hypotheses (preregistered)
See spec.md. Headline: H1 — gradient projection in SVD basis against a v_hack extracted from ~60-80 contrastive pairs reduces reward hack rate by
=30pp absolute vs vanilla GRPO at matched LeetCode pass rate (±10pp).