Anthropic publishes Claude Sonnet 4.5 safety case detail — feature-steering interventions documented in production-deployment record
Anthropic published additional detail on the Claude Sonnet 4.5 safety case this cycle, documenting the feature-steering interventions applied during pre-deployment review. The published artifacts include specific SAE features identified on risk-axis evaluations, the intervention design applied for each identified feature, and the re-measurement results after intervention. The publication is the most detailed deployment-artifact disclosure any frontier lab has made on interpretability-driven intervention.
The disclosure scope is the substantive piece. The published safety case includes the SAE features identified during risk-axis evaluation, the specific feature-steering interventions designed for each identified feature, the validation work confirming the interventions modified behavior in the intended direction without producing collateral unintended effects, and the post-intervention re-measurement results documenting the final deployed-model behavior. The artifact format is auditable in the sense that an independent reviewer can verify the methodology was followed without needing access to the underlying model weights — the steering-feature identifiers and the intervention specifications are the auditable surface.
The regulatory consequence is consequential. Combined with Gemma Scope 2's open-source toolkit infrastructure, the safety case publication produces the academic-research-plus-deployment-practice combination that regulators considering pre-deployment evaluation requirements can reference. The methodology spans the full continuum from open-source baseline (Gemma Scope 2) through production-deployment artifact (Sonnet 4.5 safety case), making the regulatory-specification surface much more tractable than starting from research-stage methodology. For other frontier labs, the published artifact is the procedural model their own safety cases will be compared against. The Mythos restriction precedent demonstrates the parallel capability-driven-release-gating mechanism at the other end of the deployment-control spectrum.
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