Add Prestation Wizard Controller

Drives the multi-step wizard: holds the form state, exposes category providers, and runs the 4-6-call submission pipeline (create → assign → location → policy).

1. vendorProductCategoriesProvider + vendorSubCategoriesProvider load top-level + nested categories on demand.
2. Form state mutations (title, thumbnail, options, variants, working hours, location, policy).
3. Submit pipeline: VendorService.createProvision → /vendor/members → assignProvisionsToMember (provision + workingHour + slotDuration + location) → addProductLocation → upsertBookingPolicy.
4. Each step bubbles errors to a single 'submitError' state slot.

• If member assignment fails after createProvision, the provision is created but orphaned — backend cleanup is manual today.
• Policy upsert is the last step; it can run independently after the rest succeeds (idempotent).
• Geoapify is used to resolve the address into lat/lng before /vendor/product-location.
• Currency, sub-category, and option values are validated client-side before the submit fires.

• lib/src/features/seller/add-prestation/provider/add_product_provider.dart:21 // vendorProductCategoriesProvider
• lib/src/features/seller/add-prestation/provider/add_product_provider.dart:44 // vendorSubCategoriesProvider
• lib/src/features/seller/add-prestation/CLAUDE.md // canonical create-flow doc

• GET/vendor/categoriesno status

  Top-level seller_services categories for the category picker.

  Response

  { seller_services: [{ id, name, ... }, ...] }

  lib/src/features/seller/add-prestation/provider/add_product_provider.dart:21 // vendorProductCategoriesProvider

  auth: seller. Direct DioHelper call from the Riverpod provider.

• GET/vendor/categories/:parentIdno status

  Sub-categories of a chosen parent category.

  Response

  { categories: Category[] }

  lib/src/features/seller/add-prestation/provider/add_product_provider.dart:44 // vendorSubCategoriesProvider

  auth: seller.

• POST/vendor/filesno status

  Multipart upload of the wizard's thumbnail / images before submit.

  Request

  FormData({ file: File, purpose: 'public' })

  Response

  { url: string }

  lib/src/features/seller/add-prestation/add-prestation.dart + thumbnail.dart // via VendorService.uploadPublicFile

  auth: seller.

CLAUDE.md in this folder is the source of truth for the multi-call sequence — keep it in lockstep with the controller. After these calls the wizard chains VendorService contracts (createProvision → assignProvisionsToMember → addProductLocation → upsertBookingPolicy) listed on the vendor-service node.