Anthropic has moved Claude Opus 5.5 fast mode out of research preview, according to the October 15 entry in its Claude Platform release notes. The same update includes a beta Compliance API feature for Enterprise organizations.
Review the Opus 5.5 request configuration
Opus 5.5 fast mode no longer requires an access request. Requests also no longer need the fast-mode beta header, while existing requests that continue to send it remain compatible.
The release notes add default fast-mode rate limits for the Start, Build and Scale usage tiers. That changes availability and configuration; it does not establish the throughput a particular application will achieve under its own request load.
Fast mode for Opus 5 and Opus 4.8 remains in research preview. Keep the relevant beta header for those models instead of removing it from a shared request configuration without checking which model each request uses.
Check the deployment platform
Opus 5.5 fast mode is also available through Microsoft Foundry. The notes specify deployments hosted on Azure.
For a team with several deployment targets, the useful migration check is to map the model and hosting platform separately. Verify the limits and request shape for the actual deployment rather than assuming a change on one surface applies identically everywhere.
Enterprise compliance adds saved instructions
A beta endpoint returns organization members' saved instructions. The update covers Instructions for Claude in claude.ai and Global instructions in Cowork, using a Compliance Access Key with the existing read:compliance_user_data scope.
This is an administrative data-access feature for Claude Enterprise organizations. Treat it as a separate change from faster inference: evaluate who is authorized to retrieve those preferences and how the returned data enters your compliance process. The release note announces capability and access requirements, without making a claim about a particular organization's retention or review policy.