Architecture and Design

Architecture and Design

Layered architecture

The architecture separates external DID/VC participants from holder-side orchestration.

Mermaid version

flowchart LR
    I[Issuer I] --> R[Registry]
    R --> V[Verifier V]
    V --> W[Holder wallet layer]

    subgraph H[Holder-side orchestration boundary]
        W --> CS[Credential store]
        W --> PP[Policy parser]
        W --> RP[Resource profiler]
        PP --> PH[Policy hash]
        CS --> D[CAPS-ZK decision layer]
        PP --> D
        RP --> D
        PH --> D
        D --> SF[Semantic filter]
        SF --> PRF[Privacy filter]
        PRF --> PF[Predicate filter]
        PF --> RF[Resource filter]
        RF --> CSCORE[Cost scorer]
        CSCORE --> BAL[Backend adapter layer]
        BAL --> BBS[BBS adapter]
        BAL --> AC[AnonCreds adapter]
        BBS --> VP[VP composer]
        AC --> VP
    end

    VP --> V

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Design principle

The selector is designed to fail closed. If no backend satisfies policy semantics and resource feasibility, it returns a rejection rather than silently downgrading to an unsafe presentation type.