Date::Error ("invalid date") deserializing organizations.get_billing_subscription — API returns proration_date: "" but the Date decoder only handles nil

Summary

sdk.organizations.get_billing_subscription raises Date::Error: invalid date while deserializing a successful (HTTP 200) response, because the live API returns "proration_date": "" on subscription items and the generated date decoder only tolerates nil, not an empty string.

Environment

• clerk-sdk-ruby 7.0.0
• Ruby 3.3.1

Reproduction

Call the endpoint for any organization whose billing subscription contains an item with no proration (in our case: an org with an active paid plan plus the upcoming default free plan item):

require "clerk"

Clerk.configure { |c| c.secret_key = ENV["CLERK_SECRET_KEY"] }
Clerk::SDK.new.organizations.get_billing_subscription(organization_id: "org_...")
# => Date::Error: invalid date

The API responds 200 with a payload shaped like:

{
  "object": "commerce_subscription",
  "status": "active",
  "subscription_items": [
    {
      "object": "commerce_subscription_item",
      "status": "active",
      "proration_date": "",
      "period_start": 1783554837166,
      "...": "..."
    }
  ]
}

Root cause

CommerceSubscriptionItem declares the field as an optional ISO date:

# lib/clerk/models/components/commercesubscriptionitem.rb:46
field :proration_date, Crystalline::Nilable.new(::Date),
      { 'format_json': { ..., 'decoder': ::Clerk::Utils.date_from_iso_format(true) } }

but the decoder only short-circuits on nil:

# lib/clerk/utils/utils.rb
def self.date_from_iso_format(optional)
  Kernel.lambda do |s|
    return nil if optional && s.nil?
    return Date.iso8601(s)   # Date.iso8601("") raises Date::Error: invalid date
  end
end

So any generated model with an optional ::Date field breaks the moment the API emits "" instead of null — which the billing subscription endpoint does for proration_date today. Isolated:

Clerk::Utils.date_from_iso_format(true).call("")
# => Date::Error: invalid date

Suggested fix

Either (or both):

• Treat blank strings as absent in the optional decoder: return nil if optional && (s.nil? || s.empty?) — presumably a fix in the Speakeasy generation config since this file is generated; or
• have the API emit null rather than "" for absent date fields, matching the OpenAPI schema the SDK is generated from.

As-is, the typed client cannot read this endpoint's real responses at all; we've had to fall back to fetching and parsing the raw JSON.

Start with lib/clerk/utils/utils.rb and the generated model at lib/clerk/models/components/commercesubscriptionitem.rb; run Clerk::Utils.date_from_iso_format(true).call("") to reproduce the failure. Check the Speakeasy generation configuration or API behavior identified in the issue, then verify organizations.get_billing_subscription can deserialize a subscription item whose proration_date is "" without raising Date::Error.