wassname
e0f33045a9
tau_axis is baked into the saved V at extract time (extract_vhack_grad zeros rows where S_i/S_0 < tau_axis before SVD output is saved), so the cached file content depends on it. The previous filename keyed only on top_k, meaning a change to tau_axis would silently serve a stale cache. Add Config.v_hack_tau_axis (default 0.0) and tag it into the filename only when nonzero — so existing v_hack_Qwen3-4B_k12.safetensors files remain reachable under the default config. Future cache-key footgun (pairs.py changes) is flagged in a comment; add a pairs hash when pair-set ablations begin. 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).