# AGENTS.md — projected_grpo

**This is novel ML research.** Not in your training data. Extrapolate carefully and without overconfidence.
**This is reasearch code** We want readable, fail fast, pseudocode like code
**Editing**: Plan, Implement, Smoke test (see setup-repo skill), subagent review, commit


see @README.md for project overview

## Project in one paragraph


Hypothesis
> Prior gradient-routing methods route with labels. We ask whether a synthetic hacking vector in can replace those labels. In this toy GRPO reward-hacking setup, it can: vGROUT reduces deploy hacking from X% to Y% while improving clean solve over vanilla. Random routing also suppresses hacks, suggesting the quarantine mechanism is powerful, but the real hacking vector gives a better hack/solve tradeoff.

Motovation: 
We want to take the tool AI labs already use, and make them better for aligment using scalable self-supervised methods. Here the hope is that intervening in the gradient itself, rather than in the reward, can stop the student picking up the hack.

Inherit global rules from `~/.claude/CLAUDE.md`.

## Writing style

Use complete declarative sentences and terminology established by the background
papers. Prefer precise descriptions such as `ground-truth monitor`, `chance-level
classifier`, `retained at deployment`, and `deployment ablation`. Avoid conversational
or project-specific shorthand such as `no-cheat`, `canary`, `honest`, `foot-gun`,
`knob`, `ships`, `coin flip purity`, and `scoreboard` when a technical term is
available. Concision should come from removing unnecessary material, not from clipped
sentences. See the qoute's below from papers for example of acceptable technical writing.

## Background definitions

### Reward-hacking environment

From Ariahw et al., [*Steering RL Training: Benchmarking Interventions Against Reward
Hacking*](docs/papers/2025_lw_ariahw_steering-rl-training-benchmarking-interventions.md):

> We call our setup the **overwrite tests loophole**. Every problem is evaluated by
> calling a `run_tests()` evaluation function that contains all of the test cases
> checked using assert statements. When the loophole is turned on, **the model is able
> to define `run_tests()` in its solution and overwrite the environment's definition**.
> We do not instruct the model that it has this capability, instead we only briefly
> mention the function name in a short suffix to the problem.

The paper defines reward hacking as a solution that passes its self-defined evaluation
function but fails the ground-truth tests.

### Absorption

From Cloud et al., [*Gradient
Routing*](docs/papers/grad_routing/paper_gradient_routing.md):

> Gradient routing induces absorption. Routing a subset of the data related to some
> knowledge or capability appears to localize that knowledge or capability more
> generally. This held for an i.i.d. subset o
> f the data (TinyStories unlearning in
> section 4.2.2), and for semantically limited data (steering scalar in section 4.2.1,
> virology unlearning in section 4.2.3, scalable oversight in section 4.3). Notably,
> this effect did not hold for DEMix, a modularity method in which localized modules
> are sequestered so that only one (per layer) participates in each forward pass. To
> explain these observations, we posit absorption: (i) routing limited data to a region
> creates units of computation or features that are relevant to a broader task; (ii)
> these units then participate in the model's predictions on related, non-routed data,
> reducing prediction errors on these data, so that (iii) the features are not learned
> elsewhere. Absorption may also amplify the features causing it. When data labels are
> semantically or quantitatively limited, absorption means that gradient routing can be
> useful even in cases where conventional training or data filtering methods are
> inadequate.

### Selective gradient masking

From Cloud et al., [*Beyond Data Filtering: Knowledge Localization for Capability
Removal in LLMs*](docs/papers/grad_routing/paper_sgtm.md):

> For samples from $\mathbf{D}_{\text{forget}}$, we apply selective gradient masking
> during the backward pass so that these samples do not update
> $\theta_{\text{retain}}$. We first compute gradients for all parameters normally, and
> then zero out gradients for $\theta_{\text{retain}}$ before applying the optimizer
> ($\nabla_{\theta}=\{\nabla_{\theta_{\text{forget}}}, 0\}$). Masking parameter
> gradients rather than activation gradients is the key distinction from the prior
> Gradient Routing method. While both approaches prevent updates to
> $\theta_{\text{retain}}$ on forget examples, masking activation gradients is more
> disruptive, because it blocks backpropagation through the masked activations,
> altering gradients for all remaining parameters. It also permits greater information
> flow from $\mathbf{D}_{\text{forget}}$ into non-forget parameters, since
> activation-gradient masking does not block updates to down-projection layers.

This project instead masks and detaches adapter branch outputs per rollout. These
output masks prevent selected branches from receiving gradients, but they are not
SGTM's direct parameter-gradient masks. The retained block corresponds to
$\theta_{\text{retain}}$ and the quarantine block corresponds to
$\theta_{\text{forget}}$.

## Vocabulary: routing, the vector, pinning, absorption
<!-- TODO do we need this now we have the full paragraphs extracted above, those are better. merge? if there are remaining concepts like routing can we use a qourteagain/ -->

Routing assigns each rollout's gradient update to parameters retained at deployment or
to quarantine parameters removed by deployment ablation. A false negative updates the
retained parameters with a reward-hacking example, whereas a false positive removes
one non-reward-hacking update. The routing threshold should therefore favor precision
over recall.

The routing score is the cosine alignment between a rollout update and `v_grad`, or
between its activations and `v_act`. These reward-hacking-minus-correct directions are
extracted from hand-authored contrast pairs before training. They do not use
ground-truth labels from training rollouts. Pinning selects score thresholds for the
retain, absorb, and route regions.

The middle region leaves both parameter blocks trainable and may permit absorption.
Calling this region `absorb` names the intended mechanism; it does not establish that
absorption occurred. `scripts/diag_pinning.py` reports score AUROC and precision at
the route threshold.

## Things the user has had to explain many times:

- Oracle-free training. The test is whether the method applies to a new RL environment
  without access to an environment-specific oracle. Requiring ground-truth
  reward-hacking labels for training rollouts invalidates the method. Using a detector
  does not by itself invalidate the method. Distinguish the following cases:
  1. The env's eval grader / full detector suite is an ORACLE, but only a MEASUREMENT
     INSTRUMENT for THIS env -- it may score the final deploy eval and nothing else. Any
     train-time use (gate routing, threshold selection, or rollout labeling) leaks a
     signal unavailable in the new environment.
  2. The disqualifier is ORACLE / GROUND-TRUTH-LABEL LEAKAGE, not detector-presence. A live
     detector is valid if it never saw the true hack-labels of the
     rollouts it judges and needs no env-specific oracle to build. By this test, of the Ariahw
     monitors: Ground-Truth (+70/90% variants) uses the oracle label of the training
     rollout; LLM judge is the fairest external baseline (generic model, no
     oracle, transfers to a new env); probe = boundary -- legitimate only insofar as it was
     trained elsewhere and transfers oracle-free, but you can neither tune nor verify it on the
     new env, so it is an open question ("could we use the probe at deployment / on a new
     dataset?"), not a usable method. A "weak detector for hack A that misses B/C/D" trained on
     this env's labels is the classic weak-LABEL setup (labelA -> suppress labelNotA); that is
     NOT our setup -- do not frame our method that way.
  3. OUR setup is `vec -> routing`: extract a hack direction `vec` from hand-built synthetic
     contrastive pairs (off-distribution, authored before observing training rollouts),
     then route each GRPO gradient by its cosine alignment to `vec`. The hand-authored
     pairs require no env-specific oracle and use no ground-truth labels from training
     rollouts. Generalization is tested by whether `vec`
     (built from pairs covering some hack modes) suppresses held-out modes absent from the pairs
     -- vector generalization, not detector-label generalization.
  4. On-distribution contrast pairs require labels for training rollouts and therefore
     violate the oracle-free training constraint. An ideal direction fit on
     oracle-labelled training rollouts, such as `mu_hack - mu_clean`, is a diagnostic
     upper bound rather than an attainable method. The available intervention is to
     improve the diversity and matching of hand-authored pairs while keeping all labels
     outside the training distribution.
- do not overconfidentaly diagnoses. if you cant think of 3+ plausible hypothesis - including bugs, subtle failures, and you being wrong about concepts - then you have lost perspective and narrow vision
- DON'T act on a new theory/diagnosis until I confirm it: don't keep building on it, and don't write it into code comments, docstrings, or docs. An unconfirmed theory baked into a comment misleads every future agent who reads it as fact. State it to me, wait for the OK, THEN write.
- DON'T inflate a diagnosis's confidence (maybe -> probably -> definitely) across turns or in writing. Keep the hedge you started with unless new evidence justifies the change, and name that evidence. Confidence creep in comments/docs is how a guess becomes "known" with no one having checked.
- I'd often afk so dont stop and ask me a question you know the likely answer, or I've already indicated or asked for, or where there is only on answer "waiting for your go ahead". I'd rather you just commit and go ahead

## The adapter setup (shapes), and why "same position = shrinkage" is subtle

<!-- User, wtf is shrinkage? -->

Per Linear `W:[d_out,d_in]`, rank `r`. Two adapters: deployed + quarantine (ablated at deploy).

- PiSSA/AntiPaSTO: `W = U S Vh`, `U:[d_out,r]`/`Vh:[r,d_in]` FROZEN. Train `delta_S:[r]`
  (deployed) + `delta_S_hack:[r]` (quarantine) -- diagonals in the SAME frozen basis, `r`
  scalars each. forward `y = W@x + U @ ( (Vh@x) * (delta_S + delta_S_hack) )`.
- LoRA-frozen-B (current `wrap_model_with_lora_frozen_b`): `A:[r,d_in]` trainable, `B:[d_out,r]`
  FROZEN+SHARED, `A_hack:[r,d_in]` quarantine. forward `y = W@x + B @ ((A + A_hack) @ x)`.
  Shared B -> `A.grad == A_hack.grad` pre-routing.

The forward sees ONLY the sum. So routing that carves one gradient into kept+routed and
ablates the routed part at deploy is, by DEFAULT, a MAGNITUDE split: deploy = vanilla minus
`qE` of the update = "earlier-training vanilla" = less (late-emerging) hacking, no direction.
That is the shrinkage NULL. Vanilla today already has `delta_S_hack=0` (never routed into), so
it is "two adapters, one empty"; routeV's deploy just lost `qE` of the same update.

Shrinkage is NOT inevitable. Two things break it:
1. Adapter EXPRESSIVENESS. `delta_S` is `r` per-axis scales (near-eigenvalue tweaks); `A` is a
   full `r*d_in` unfrozen map. Under a DISCRIMINATING gate (f high on hack rollouts, low on
   solve) the deployed `A` accumulates `Σ_solve g` and `A_hack` accumulates `Σ_hack g` -- real
   separation. `delta_S` can separate far less (only along `r` fixed axes). So LoRA is less
   doomed to shrinkage than PiSSA even with shared B.
2. STRUCTURAL separation: give the quarantine its OWN frozen encoder/decoder (`U2/Vh2`, or its
   own trainable `B_hack`), so the two adapters live in different subspaces, `∂L/∂deployed !=
   ∂L/∂quarantine`, and deploy-ablation removes a different FUNCTION, not a slice of the same
   update.

So shrinkage-vs-direction is decided by (gate discrimination) x (adapter expressiveness +
structural separation), NOT by "same position" alone. Controls: capacity-matched vanilla (two
empty adapters, or one 2x adapter, no routing) isolates parameter count; non-directional
routing at matched `qE` isolates shrinkage. (I did not have this straight on first pass -- the
trap is calling same-position routing "shrinkage" without checking the gate/expressiveness.)

## Extra instructions:

- When you queue a job, follow with `pueue follow | tail` in bg so you are woken on fail or finish
- for every task, it's a goal of subgoal, be clear on UAT (user acceptance test), use you task list to track the goal and non trivial UAT, and it's not finished untill you have 1) collected the evidence 2) sanity checked it with a fresh eyes subagent 3) given the user the link to it's location
- say less, just answer my questions, and concisly address the top point unless I ask for more - otherwise there is too much for me to review and read

## Files

For the setup, read these:
- [docs/human_journal.md](docs/human_journal.md) -- the user's notes on the method. The novel
  part is routing by an extracted vector rather than per-example labels. The SVD adapter is a
  detail, not the novel experiment. Whether the direction, the routing, or the SVD adapter
  drives the suppression is an open question (random directions match in the controls).
- [docs/writeup/main.tex](docs/writeup/main.tex) -- the writeup: thesis and claims C1-C4.
- [docs/papers/grad_routing/paper_gradient_routing.md](docs/papers/grad_routing/paper_gradient_routing.md)
  -- Cloud et al. Expand-Route-Ablate, the gradient-routing prior.

- Read [docs/brainstorm/extracted_prefs.md](docs/brainstorm/extracted_prefs.md) for design rationale.
- New sweep arms get recipes in [justfile](justfile) with `# H:` hypothesis comments.
- `just smoke` before any real run (~1-2 min, beartype on, real pipeline on tiny inputs).
- Real runs go through `pueue` on the 96GB GPU box. Label each job with `why:` and `resolve:`.
- Head [RESEARCH_JOURNAL.md](RESEARCH_JOURNAL.md) for latest results.
- No `tests/` dir; `smoke` is the correctness gate. Unit checks are `scripts/verify_*.py`
  (assert + exit nonzero), wired into the `smoke` recipe so every smoke runs them.
- Every load-bearing invariant gets a `verify_*.py` gate, written in the same commit as
  the claim -- "the tests passed" means nothing if the property was never tested.

On pairs. A routing pair is one SAME-PROMPT (hack, clean) completion duo: pos=the
reward-hack, neg=the correct solution, vector = grad(prompt+hack) - grad(prompt+clean).
Like persona steering pairs, MATCH everything but the axis -- same
prompt, similar length/style -- so hack-vs-clean is the only thing separating them
(else style competes with the trait; see the style-confound section of the doc below).
There is NO problem_id semantics: the only "id" is which completion is the hack side
and which is the clean side. Two pairs with identical hack+clean but DIFFERENT prompts
are DISTINCT (different gradient). Authored pairs are off-distribution and hand-written;
pool-derived pairs (e.g. prog_wide_clean) may contain training-distribution labels and
are unsuitable for the primary oracle-free result.
- ./docs/personas/how_to_rewrite_pairs.md
- ./docs/personas/how_to_write_personas.md  -- pos/neg pair authoring rules + style confound
- ./docs/personas/personas_kept.md
- ./data/pairs/hack_pairs.md  -- headline multi-view pairs; supports `#all-in-one@tag`
- ./data/pairs/pair_diagnostics.md  -- semantic-framing experiments + placebo controls
- ./docs/personas/pairset_audit.md  -- pair quality, provenance, and use recommendations

On concepts such as "what are contrastive pairs" or "why SVD space" grep
- ./docs/vendor/AntiPaSTO_concepts/README.md

For the original paper (the substrate: reward-hacking LeetCode env)
- LessWrong post: ./docs/papers/2025_lw_ariahw_steering-rl-training-benchmarking-interventions.md
- Code: ./docs/vendor/rl-rewardhacking

For the gradient-routing prior (SGTM = latest gradient-routing paper, same authors as
the original; source of the absorption/leakage vocab)
- ./docs/papers/grad_routing/paper_sgtm.md

