This session will convene a focused, collaborative design sprint to establish a clear, implementable model for integrating Categorical Variant Representation (Cat-VRS) with the Beacon protocol. The core challenge is defining how categorical variant classifications, such as "gain-of-function," "likely pathogenic," or "variant of uncertain significance", can be reliably used as query filters and response attributes in Beacon, moving beyond purely coordinate-based matching. This work is essential for enabling phenotype- and consequence-aware genomic discovery, a need frequently expressed by clinicians and translational researchers.

Participants will engage in a hands-on mapping and prototyping exercise, using real-world variant annotation datasets to define a standardised schema for conveying categorical variant assertions within Beacon's query and response framework.

The goal is to produce a consensus-driven, technical deployment roadmap that specifies how Cat-VRS terminology and concept expressions can be incorporated into current Beacon implementations, ensuring interoperability between clinical variant knowledge bases and federated Beacon networks.

Meeting aims: The goal of this session is to produce a shared set of collaboration scoping, requirements, and preliminary technical design artifacts that will enable a coordinated Beacon pilot built on Cat-VRS.

Anticipated outputs from this meeting include:

• draft Representative Query & Variant Test Set;
• description of current variant types exchanged within Beacon v2.0, and aspirational variant types that Beacon hopes to support within Beacon v3.0;
• an initial, non-normative collection of representative Beacon query and variant examples (e.g. JSON payloads) intended to concretise requirements and serve as a shared validation target during development;
• collaboration cadence and points of contact: who, when, and how often to hold virtual follow-up meetings to keep development on-track;
• Beacon/Cat-VRS Requirements Statement (required data types, value domains, and representational constraints, and algorithmic and matching considerations that may influence Cat-VRS design and implementation).
• Pilot Implementation Timeline (target milestones for a Beacon 3.0 pilot leveraging VRS and cat-VRS, and dependencies and critical path items).

If time permits us to get into the weeds, additional topics might include:

• candidate Cat-VRS Recipes to support current and aspirational Beacon Use Cases;
• candidate Cat-VRS Constraint Proposals
• proposals for new constraints or proposals to update existing constraints