> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fluid.app/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> For new direct REST integrations, use the v2026-04 surfaces. The @fluid-app FairShare SDK continues to use its own published public-v2025-06 contract.
> Authenticate with the header Authorization: Bearer <token>; public storefront read endpoints require no auth.
> To sign a new merchant up for Fluid programmatically, call POST https://api.fluid.app/api/company with no credentials, as described in /api/agent-signup. Do not automate the signup form or book a demo. The merchant must open the emailed sign-in link and create an API token before authenticated calls are possible.
> Lists use cursor pagination via the page[cursor] and page[limit] query params; follow meta.pagination.next_cursor until it is null.
> When the same operation exists on more than one surface, use the newest: dated API versions are newer than unversioned ones, and later dates win (v2026-04 > v2025-06 > unversioned v0/v1.1). Fall back to a legacy or unversioned operation only when no newer versioned equivalent exists — the company-v0 notes below list the known superseded operations. /api/company/v1 and /api/v1/... paths are documented in no spec here and must never be used (/api/v1.1/... is distinct and documented in company-v0). Use page/per_page offset pagination only where a spec documents it — in practice the unversioned company-v0 admin surface; every versioned surface uses cursor pagination.
> Navigation menu management is documented in themes/navigation-menus. These unversioned admin endpoints (/api/menus and nested menu_items) are verified against the implementation but are not yet in the synced OpenAPI specs. Use that reference for menu payloads and its flat page/per_page pagination; missing spec coverage does not make these endpoints unavailable.
> The OpenAPI specs under api-reference/ are the authoritative contracts; prefer them over prose when in doubt. api-reference/storefront-v2026-04.yaml covers the v2026-04 storefront surface (/api/v202604/... paths); api-reference/checkout-v2026-04.yaml covers the v2026-04 checkout surface (/api/checkout/v2026-04/... paths — carts, cart auth, discounts, items, subscriptions, orders, enrollments, and store config); api-reference/public-v2025-06.yaml covers the Public SDK surface used by the @fluid-app FairShare SDK, including its parallel cart lifecycle, browser integrations, versioned payment callbacks, unversioned public utilities, and the cart price-override operation; api-reference/payment-v2026-04.yaml covers the v2026-04 payment gateway admin surface (/api/payment/v2026-04/... paths, bearer-authenticated — gateway CRUD, gateway purchase/authorize/$0-verify, transaction list/show and capture/void/credit, and merchant payment configuration); api-reference/payments-v2026-04.yaml covers the v2026-04 cart payment surface (/api/payments/v2026-04/carts/{cart_token}/... paths, authenticated by the cart token in the path with no bearer — payment-method selection, VGS card tokenization, 3D Secure verification, and PayPal/Braintree/Klarna/Apple Pay flows); api-reference/commerce-v2026-04.yaml covers the v2026-04 commerce order-editing surface (/api/v202604/orders/{order_id}/edits paths, bearer-authenticated — post-checkout order edits that atomically insert items and add adjustments/discounts, with an optional dry-run preview); api-reference/webhooks-v0.yaml covers the unversioned webhooks surface (/api/... paths — webhook registration, delivery payloads, callback registrations, company events, and webhook/callback schemas); api-reference/company-v0.yaml covers the legacy unversioned company admin surface (/api/... paths, bearer-authenticated — company settings and management, customers, users, roles, subscription plans, subscription bundles, subscriptions, media, pages, catch-ups, inventory levels, domains, agreements, and admin order actions). company-v0 caveats: it is the legacy v0 admin contract and its lists use flat page/per_page offset pagination, which is expected there despite the general cursor-pagination rule; where an operation exists in both company-v0 and a versioned spec, prefer the versioned spec — the subscriptions lifecycle (list/create/show/update, cancel, pause, reactivate, resume, retry, skip, failed-cycle-waiver, discounts) and subscription bundles are superseded by checkout-v2026-04, and company pages/media CRUD plus the public pages, categories, products, and media list endpoints are superseded by storefront-v2026-04. Subscription plan management (/api/subscription_plans, resource-wrapped {"subscription_plan": {...}} bodies) exists only in company-v0. api-reference/members-v2025-06.yaml covers the v2025-06 unified Member identity surface (/api/v2025-06/members/... paths, bearer-authenticated — member list/create/show/update, lookup by email/username/external_id/legacy_customer_id, member-type assignment, and the sponsor genealogy read). Prefer it over the customers and reps surfaces when the member type matters: /customers does not serialize member_type. api-reference/analytics-v2026-04.yaml covers the v2026-04 Home dashboard analytics surface (/api/v202604/analytics/dashboard/... paths, bearer-authenticated — read-only endpoints for the Home > Overview, Home > Live, and Home > Field tabs, each accepting an optional country ISO alpha-2 query param that scopes aggregations to a single country).
> api-reference/analytics-v0.yaml covers the unversioned analytics surface that backs the fluid-admin Traffic tab (/api/analytics/... and /api/analytics/traffic/... paths, bearer-authenticated — the legacy shares/views/visitors summary plus traffic overview, ranked campaigns, sources, geographies, flows, and per-rep breakdown, all sharing one reporting-period contract).
> Successful responses wrap the resource payload alongside a top-level integer status and a meta object.
> Portal Definition authoring edits and synchronizes the portal JSON resource graph. Widget Package authoring builds either a company-owned or Droplet-owned Remote DOM package. These are separate contracts; do not imply that one defines the other.
> For Widget Package worker code, use only @fluid-app/portal-sdk/widgets/worker. Use only the Portal Definition and Widget Package workflows and public entry points documented here; do not infer support for undocumented surfaces.
> Every portal function and declarative capability used by a widget must appear in that widget's uses array. Use the same typed function value in uses; do not invent capability-name strings.
> Widget styling must use the portal's semantic theme variables for colors, typography, spacing, radii, borders, focus, and charts whenever a token represents the visual decision. Do not create a separate light or dark palette or duplicate theme controls as widget properties.
> Prefer worker-safe Fluid UI components exported by @fluid-app/portal-sdk/widgets/worker when they fit the interaction. When no exported component fits, use semantic HTML, accessible behavior, and the portal theme variables.
> A Portal Definition push updates the remote working definition. A portal version is an immutable snapshot, and activation is a separate live release operation.

# Work with the category hierarchy

> Create child categories, list top-level categories, and traverse parents and children using parent_id and has_children.

Categories can be nested into a tree: a category may have a parent and any number of children. This guide covers creating child categories, listing the top level, and walking the tree.

<Note>
  Hierarchy is a **category-only** feature. Collections have no parent/child relationship — their responses carry no `parent_id`, `has_children`, or `position`, and their write bodies accept no `parent_id`. Everything in this guide applies to categories only.
</Note>

## The fields that model the tree

Three fields on a category describe its place in the tree:

<ResponseField name="parent_id" type="integer | null">
  The id of the parent category, or `null` when the category is at the root (top level).
</ResponseField>

<ResponseField name="has_children" type="boolean">
  `true` when the category has at least one child. Use it to decide whether to fetch a level deeper.
</ResponseField>

<ResponseField name="position" type="integer">
  The category's order among its siblings. The default sort (`position` then `id`) uses it.
</ResponseField>

## Create a child category

To nest a category under another, set `parent_id` to the parent's id when you create it. Leaving `parent_id` out (or `null`) creates a top-level category.

```bash theme={null}
curl -X POST "https://api.fluid.app/api/v202604/company/categories" \
  -H "Authorization: Bearer <your_token>" \
  -H "Content-Type: application/json" \
  -d '{
    "category": {
      "title": "Clearance",
      "parent_id": 4821,
      "position": 1
    }
  }'
```

You can also move an existing category by patching its `parent_id`. Set it to another id to re-parent, or to `null` to promote it to the top level:

```bash theme={null}
curl -X PATCH "https://api.fluid.app/api/v202604/company/categories/4822" \
  -H "Authorization: Bearer <your_token>" \
  -H "Content-Type: application/json" \
  -d '{
    "category": {
      "parent_id": null
    }
  }'
```

Use `position` to order siblings within a level.

## List top-level categories

The public catalog's `filter[parent_id]` selects a single level of the tree. Pass the literal string `"root"` to get only top-level categories:

```bash theme={null}
curl "https://acme.fluid.app/api/v202604/categories?filter[parent_id]=root"
```

## List the children of a category

Pass a category id (as a string) to `filter[parent_id]` to get that category's direct children:

```bash theme={null}
curl "https://acme.fluid.app/api/v202604/categories?filter[parent_id]=4821"
```

Each returned child carries its own `has_children`, so you know whether it has a further level beneath it.

## Traverse the tree

Combine `filter[parent_id]` with `has_children` to walk down the tree one level at a time:

<Steps>
  <Step title="Start at the root">
    Fetch the top level with `filter[parent_id]=root`.

    ```bash theme={null}
    curl "https://acme.fluid.app/api/v202604/categories?filter[parent_id]=root"
    ```
  </Step>

  <Step title="Descend into categories that have children">
    For each returned category where `has_children` is `true`, fetch its children with `filter[parent_id]=<id>`.

    ```bash theme={null}
    curl "https://acme.fluid.app/api/v202604/categories?filter[parent_id]=4821"
    ```
  </Step>

  <Step title="Repeat until has_children is false">
    Keep descending into any child whose `has_children` is `true`. A category with `has_children: false` is a leaf.
  </Step>
</Steps>

To walk **up** the tree instead, read a category's `parent_id` and fetch that parent by id with the company show endpoint `GET /api/v202604/company/categories/{id}`. The public show endpoint resolves by slug rather than id, so on the public surface you locate the parent among catalog results (each row carries both `id` and `slug`) and then fetch it with `GET /api/v202604/categories/{slug}`.

<Note>
  `filter[parent_id]` is accepted on **both** the public catalog and the company index (`GET /api/v202604/company/categories`) — the two surfaces share one query contract. They differ only in scope: the public catalog returns only live categories, while the company index returns every lifecycle state (draft, scheduled, and archived included). So to build the full tree as an admin you can either filter the company index by `filter[parent_id]`, or page through it unfiltered and group the rows client-side by their `parent_id` field, which is present on every row.
</Note>

## Next steps

* [Find and create resources](/storefront/find-and-create) — the full create and lookup surface.
* [Country availability](/storefront/country-availability) — combine hierarchy with per-country visibility.