Expose multi-ring batch verification (ark-vrf #92)

Summary

davxy/ark-vrf#92 ("Multi-ring batch proof", merged Apr 2026, shipped in ark-vrf 0.5.0) adds a multi-ring batch verifier: proofs from multiple rings that share the same KZG SRS can be aggregated into a single batched pairing check. This is a verification-speed optimization beyond the single-ring batching we expose today.

This issue tracks adopting that capability and exposing a multi-ring batch binding from verifiablejs.

Where we stand in the dependency chain

verifiablejs (WASM bindings)
  └─ paritytech/verifiable  (pinned rev f65b39df…)
        └─ ark-vrf 0.5.0  ← multi-ring batch already present here

• ark-vrf 0.5.0 (which contains #92) is already transitively in our build via the pinned verifiable rev. The crypto primitive is compiled in.

• The blocker is not ark-vrf. It's the verifiable crate's API surface. GenerateVerifiable::batch_validate takes a single members commitment:

  fn batch_validate(
      config: Self::Config,
      members: &Self::Members,            // <-- one ring
      proofs: &[BatchProofItem<Self::Proof>],
  ) -> Result<Vec<Alias>, Error>
  

  So every BatchProofItem is verified against the same ring. Multi-ring batching is not reachable through this signature.

• Our batch_validate binding (packages/verifiablejs/src/lib.rs:273) inherits the same single-ring limitation.

What's needed (upstream-gated)

1. paritytech/verifiable must expose a multi-ring batch method on GenerateVerifiable (e.g. accepting &[(Members, Vec<BatchProofItem>)] or equivalent) that calls into ark-vrf's multi-ring BatchVerifier.
2. Then verifiablejs adds a new binding, e.g. multi_ring_batch_validate, taking multiple SCALE-encoded commitments + their proof items, returning aliases grouped per ring.

Action

• Open / track a request on paritytech/verifiable to surface the multi-ring batch API.
• Once available, bump the verifiable rev and add the multi_ring_batch_validate binding + tests.

This is a perf enhancement, not a correctness fix — no urgency. Filing to track until upstream verifiable is ready.

Start with packages/verifiablejs/src/lib.rs:273 and review the existing single-ring batch_validate binding. Check whether paritytech/verifiable has added the required multi-ring GenerateVerifiable API; the work is blocked until that upstream surface exists. Done means bumping the verifiable revision, adding multi_ring_batch_validate for grouped commitments and proof items, and adding tests.