Using Claude Fable 5 or Mythos 5 on Amazon Bedrock requires opting into provider_data_share, a mandatory data retention mode that sends prompts and outputs to Anthropic for 30-day retention with human review. This breaks Bedrock's core value proposition — that inference data never leaves the AWS boundary — which was the basis for procurement approvals in regulated industries. Anthropic frames this as a safety requirement for frontier-class models, not training data collection, but the compliance implications are significant: Anthropic becomes a sub-processor, requiring DPA amendments, BAA reviews for healthcare, and CLOUD Act exposure concerns for European organizations. The rollout drew criticism for lack of advance notice to security teams and a monitoring gap where Bedrock Mantle logs to a different CloudTrail event source. AWS has since published isolation guidance using SCPs. Three days after launch, Anthropic asked AWS to revoke access to both models citing US export control compliance, leaving enterprises to decide whether to stay on older models or accept a new data governance posture for frontier models.
