Function build_rpc_ops_filter 

pub fn build_rpc_ops_filter(
    ops: &'static [OpDescriptor],
) -> impl Fn(&Request<Body>) + Send + Sync

Build a rate-limit filter function for RPC schemas.

Returns a function that:

• Extracts op_id from /rpc/{op_id} paths
• Looks up the op in the provided descriptors
• Returns false (exempt) if rate_limited_by_default is false
• Returns true (apply rate limit) if the op participates, or if lookup fails

Fails closed: if descriptor lookup misses for any reason, the op is rate-limited. This prevents accidental exemptions from missing data.

/rpc/batch is always rate-limited regardless of its contents — see the module-level “Known limitation” doc above.

Since ADR 0015 slice 2 (cratestack#877) this is a projection of build_rpc_op_resolver — one lookup shared with idempotency. Every case above that resolver answers OpAdmission::unresolved, whose rate_limited_by_default is true: the same fail-closed answer. For a router mounted with Router::nest, pass build_rpc_op_resolver_with_prefix to super::RateLimitLayer::with_op_resolver instead.