praxagent / Technical record
Notes tagged Jacobian-Lens
Research notes collected under Jacobian-Lens, ordered by date.
A Linear Nudge, a Nonlinear Wake
We followed controlled hidden-state edits through the final 29 blocks of Llama 3.3 70B. The delivered edits scaled linearly with dose in all 24 test cells on the prespecified panel; the model's final hidden state did in …
Why Experimental Details Matter: Recovering from a Flawed Interpretability Study
A striking interpretability result was frozen in public git before it ran and still came from a flawed comparison. We trace how prompt echo, a domain-mismatched lexicon, and unequal stakes produced an overconfident …
Can a Jacobian Lens Detect SAE Steering?
A prospectively frozen Llama 3.3 70B experiment asks whether an auditor can tell, from a steered internal state alone, which public SAE feature was steered. Under a fixed Jacobian-lens readout the answer is no; the same …
Open-sourcing (and Auditing) a Jacobian Lens for Qwen3.5-397B
Praxagent is open-sourcing a Jacobian lens for Qwen3.5-397B-A17B, fitted on 24 WikiText prompts. As of July 10, 2026, to our knowledge no public Jacobian lens has been fitted for a larger base model. A pre-registered …