Restore CRLF line endings in ManagesBalance

Release 3.3.0

CHANGELOG.md

@@ -0,0 +1,74 @@
+# Changelog
+
+## Unreleased
+
+Preferences, charges and the billing limit; they need an Anikeen ID release that supports them.
+
+### Added
+
+- Preferences of any user with the app's token (trusted apps, registered by Anikeen per
+  namespace): `preferencesByUserId()`, `preferenceByUserId()`, `setPreferenceByUserId()`,
+  `deletePreferenceByUserId()` and `findUserIdByPreference()` (the user holding a value of a unique
+  key, `null` when nobody does).
+- The user's shared preferences with their token: `globalPreferences()`, `globalPreference()`,
+  `setGlobalPreference()` and `deleteGlobalPreference()` on `Billable`, cached per instance.
+- `Resources\Preference` and `Resources\Preferences`; `Enums\SharedPreference` and
+  `Enums\Appearance`.
+- Conditional writes: `ifVersion` (`If-Match`) and `createOnly` (`If-None-Match: *`);
+  `PreconditionFailedException` (a subclass of `ApiException`) for 412 with `currentVersion()`.
+- Scopes `Scope::PREFERENCES`, `PREFERENCES_READ` and `PREFERENCES_CLIENT`.
+- Webhook event `order.refunded` (`EventType::ORDER_REFUNDED`).
+- Charges on a user's monthly bill for trusted apps: `createChargeForUser()` (with an idempotency
+  key), `findChargeForUser()` and `voidChargeForUser()`; `Resources\AppCharge`.
+- The user's billing limit for trusted apps: `billingLimitForUser()` and `Resources\BillingLimit`
+  (`allows()` is advisory); the `billing_limit` key of `billingOverview()` is documented.
+- `ApiException::isBillingLimitReached()` for 409 `billing_limit_reached`.
+- Opt-in webhook events `billing_limit.reached` and `billing_limit.available`
+  (`EventType::BILLING_LIMIT_REACHED`, `BILLING_LIMIT_AVAILABLE`).
+- An optional trailing `$headers` argument on `AnikeenId::request()`, `get()`, `post()`, `put()`,
+  `delete()` and `AppRequest::send()`; calls without it send the same request as before.
+
+## 3.3.0 (2026-11-06)
+
+App billing features; they need an Anikeen ID release that supports them.
+
+- Free trials: `trial_days` / `trial_ends_at` (optional `trial_once`, `trial_payment_method` with
+  `TrialPaymentMethod::REQUIRED` / `OPTIONAL`) when creating subscriptions and checkout sessions;
+  `Subscription::isTrial()`.
+- Discounts per billed period: `discount` with `percent_off` or `amount_off`, `duration` and `label`.
+- Plan changes of running subscriptions: `AppSubscription::change()` (`apply: now` or
+  `period_end`) and `AppSubscription::cancelScheduledChange()`.
+- App orders: order lines with subscription, period, net amount and discount;
+  `AppOrders::invoicePdf()`. Confirmable orders of trusted apps (`confirm: true`).
+- Billing portal links that work without a login: `createBillingPortalLinkForUser()` and
+  `appBillingPortalUrl()`.
+- Webhook events `subscription.trial_will_end`, `subscription.discount_ended`,
+  `subscription.updated` and `subscription.renewed` (`EventType::SUBSCRIPTION_*`);
+  `data.reason` with `CancellationReason::TRIAL_ENDED_WITHOUT_PAYMENT_METHOD`.
+
+## 3.2.0 (2026-11-06)
+
+Elapsed-period billing and user lookup; they need an Anikeen ID release that supports them.
+
+- `AppSubscription::checkout()` takes `billElapsedPeriods` and `maxNetAmount`: a subscription
+  started more than one period ago is billed for its elapsed periods too, up to the given net
+  amount (409 `elapsed_amount_exceeded` with `net_amount`, `elapsed_periods_not_allowed`). Calls
+  without the new arguments send the same request as before.
+- `ApiException::body()` returns the JSON body of Anikeen ID's error response, e.g. its
+  `net_amount`.
+- Add `AnikeenId::findUserByEmail()` for trusted apps: looks up an account by email address
+  (regardless of case) without creating one, null when there is none.
+- `createUser()` documents `name`, `password_confirmation` and `send_invitation` (a newly created
+  account gets an invitation mail to set a password) and the response fields `created` and
+  `invitation_sent`.
+
+## 3.1.0 (2026-11-05)
+
+- Add the scope `products:read` (`Scope::PRODUCTS_READ`) for read-only access to the product APIs
+  of the Anikeen Console.
+- Add the reseller scopes `reseller-customers:read`, `reseller-customers`, `reseller-grants` and
+  `reseller-orders` (`Scope::RESELLER_CUSTOMERS_READ`, `Scope::RESELLER_CUSTOMERS`,
+  `Scope::RESELLER_GRANTS`, `Scope::RESELLER_ORDERS`) for the reseller API of the Anikeen Console.
+- Document the scope schema and the new scopes in the README.
+
+Older releases: see the [GitHub releases](https://github.com/anikeen-com/id/releases) and tags.

README.md

@@ -4,7 +4,7 @@
 [![Total Downloads](https://img.shields.io/packagist/dt/anikeen/id.svg?style=flat-square)](https://packagist.org/packages/anikeen/id)
 [![License](https://img.shields.io/packagist/l/anikeen/id.svg?style=flat-square)](https://packagist.org/packages/anikeen/id)
 
-PHP Anikeen ID API Client for Laravel 11+
+PHP Anikeen ID API Client for Laravel 12+
 
 Sign in with Anikeen ID and let your users pay with their Anikeen ID account: one-off orders,
 subscriptions and physical goods, with invoices, VAT and payment handled by Anikeen ID.
@@ -16,11 +16,12 @@ subscriptions and physical goods, with invoices, VAT and payment handled by Anik
 3. [Sign in with Anikeen ID](#sign-in-with-anikeen-id)
 4. [Payments](#payments)
 5. [Trusted apps](#trusted-apps)
-6. [API authentication](#api-authentication)
+6. [Preferences](#preferences)
-7. [General](#general)
+7. [API authentication](#api-authentication)
-8. [Examples](#examples)
+8. [General](#general)
-9. [Documentation](#documentation)
+9. [Examples](#examples)
-10. [Development](#development)
+10. [Documentation](#documentation)
+11. [Development](#development)
 
 ## Installation
 
@@ -71,7 +72,7 @@ Add to `config/services.php` file:
 
 ### Event Listener
 
-In Laravel 11, the default EventServiceProvider provider was removed. Instead, add the listener using the listen method on the Event facade, in your `AppServiceProvider` boot method:
+Since Laravel 11, the default EventServiceProvider provider was removed. Instead, add the listener using the listen method on the Event facade, in your `AppServiceProvider` boot method:
 
 ```php
 public function boot(): void
@@ -160,6 +161,35 @@ if ($result->success()) {
 }
 ```
 
+### Scopes
+
+Scopes follow one schema: `resource` grants full access, `resource:read` read-only access and
+`resource:client` access to what the app or token created itself. All of them are constants on
+`Anikeen\Id\Enums\Scope`, e.g. `Scope::ORDERS_READ`.
+
+The Anikeen Console accepts personal access tokens and OAuth tokens (no client credentials) with
+these scopes for its product and reseller APIs:
+
+| Scope | Constant | Grants |
+|-------|----------|--------|
+| `products:read` | `Scope::PRODUCTS_READ` | view the products of your teams |
+| `reseller-customers:read` | `Scope::RESELLER_CUSTOMERS_READ` | view a reseller team's customers and invitations |
+| `reseller-customers` | `Scope::RESELLER_CUSTOMERS` | manage customers: invite, resend, remove logins (includes reading) |
+| `reseller-grants` | `Scope::RESELLER_GRANTS` | grant customers access to products and revoke it |
+| `reseller-orders` | `Scope::RESELLER_ORDERS` | order products for customers, charged right away |
+
+A full reseller scope includes reading. `user` and `*` do not open the reseller endpoints: the
+token has to carry the reseller scope itself. For the product APIs there is only `products:read`;
+changing products needs `user`.
+
+Anikeen ID's [preferences](#preferences) use these scopes:
+
+| Scope | Constant | Grants |
+|-------|----------|--------|
+| `preferences:read` | `Scope::PREFERENCES_READ` | read the user's shared preferences (`global`) |
+| `preferences` | `Scope::PREFERENCES` | read and change them |
+| `preferences:client` | `Scope::PREFERENCES_CLIENT` | app tokens: the preferences of any user, in the namespaces Anikeen registered for the app |
+
 ### Change the default access token / refresh token field name
 
 If your access / refresh token fields differ from the default `anikeen_id_access_token` / `anikeen_id_refresh_token`, you can specify the field name in the `AppServiceProvider` boot method:
@@ -184,11 +214,14 @@ public function boot(): void
 | Something that recurs (a pass, a plan) | [Subscriptions](#subscriptions) | user | the user, on Anikeen ID |
 | Several subscriptions in one step | [Checkout sessions](#checkout-sessions-the-user-confirms-several-subscriptions-at-once) | user or app | the user, on Anikeen ID |
 | Usage billing from your backend, without the user online | [App subscriptions](#app-subscriptions-trusted-apps-no-user-token) | app | your app (trusted apps only) |
+| Single items on the user's monthly bill (e.g. a shipped item) | [Charges](#charges-and-billing-limit-trusted-apps) | app | your app (trusted apps only) |
 
 Most apps are third-party apps: they create an order or subscription as a draft, send the user to
 Anikeen ID to confirm and pay, and get the user back afterwards. Anikeen ID shows the items, asks
 for missing addresses, takes the payment and writes the invoice. Trusted apps (operated by
-Anikeen) can also charge directly; see [Trusted apps](#trusted-apps).
+Anikeen) can also charge directly; see [Trusted apps](#trusted-apps). For a per-item charge on
+the user's monthly bill use `createChargeForUser()`, not `createOrderForUser()`: an order is a
+separate one-off purchase, charged on its own.
 
 The flow, as in a typical shop:
 
@@ -361,8 +394,102 @@ same value as `status`):
 | `expired` | Paused and ran out; `resume()` starts a new period | no |
 | `cancelled` | Cancelled for good | no |
 
-There are shortcuts for each: `isDraft()`, `isPaused()`, `isCancelling()`, `isExpired()`,
+There are shortcuts for each: `isDraft()`, `isTrial()`, `isPaused()`, `isCancelling()`,
-`isCancelled()`. App subscriptions (`appSubscriptions()`) have the same methods.
+`isExpired()`, `isCancelled()`. App subscriptions (`appSubscriptions()`) have the same methods.
+
+#### Free trials
+
+Give a subscription a free trial with `trial_days` (1–365, counted from the user's confirmation or
+the checkout) or a fixed `trial_ends_at` (ISO 8601, in the future), not both. The subscription
+starts right away with `status` `trial` and nothing billed; the first period is billed when the
+trial ends. `trial_once` refuses the trial if the user already had one with your app in the same
+`group` (422 when creating, 409 `trial_already_used` when checking out):
+
+```php
+$subscription = $user->subscriptions()->create([
+    'name' => 'Pixel Stream Pass',
+    'unit' => 'month',
+    'price' => 6.714286,
+    'trial_days' => 14,
+    'trial_once' => true,
+]);
+```
+
+A few days before the trial ends, Anikeen ID sends `subscription.trial_will_end`
+(`EventType::SUBSCRIPTION_TRIAL_WILL_END`), e.g. to remind the user; `data.payment_method_missing`
+tells you whether the user still has to add a payment method. Cancelling during the trial
+bills nothing. Trials work the same for app subscriptions and per subscription of a checkout
+session.
+
+By default the user needs a payment method to confirm a trial. With `trial_payment_method`
+`TrialPaymentMethod::OPTIONAL` (only together with a trial; `TrialPaymentMethod::REQUIRED` is the
+default) the user can confirm it without one, as long as nothing else has to be paid: in a
+checkout session every subscription has to be such a trial. The confirmation page tells the user
+to add a payment method before the trial ends. If there is still none then, the subscription is
+**cancelled** at the trial's end instead of billed: `status` `cancelled`, `cancellation_reason`
+`CancellationReason::TRIAL_ENDED_WITHOUT_PAYMENT_METHOD`, `subscription.cancelled` with
+`data.reason` set to the same value, and no `subscription.renewed`. Adding a payment method later
+doesn't bring it back – create a new subscription. The trial still counts for `trial_once`.
+Anikeen ID also mails the user a few days before such a trial ends without a payment method.
+
+```php
+use Anikeen\Id\Enums\CancellationReason;
+use Anikeen\Id\Enums\TrialPaymentMethod;
+use Anikeen\Id\Webhooks\EventType;
+
+$subscription = $user->appSubscriptions()->create([
+    'group' => $teamId,
+    'name' => 'Uptimr Pro',
+    'unit' => 'month',
+    'price' => 19.00,
+    'trial_days' => 14,
+    'trial_payment_method' => TrialPaymentMethod::OPTIONAL,
+]);
+
+// in your webhook handler
+$data = $event['data'];
+
+match ($event['type']) {
+    EventType::SUBSCRIPTION_TRIAL_WILL_END => $data['payment_method_missing']
+        ? Reminder::addPaymentMethod($data['object']['id'])
+        : null,
+    EventType::SUBSCRIPTION_CANCELLED => $data['reason'] === CancellationReason::TRIAL_ENDED_WITHOUT_PAYMENT_METHOD
+        ? Pass::downgrade($data['object']['id'])
+        : Pass::revoke($data['object']['id']),
+    default => null,
+};
+```
+
+#### Discounts
+
+A `discount` (e.g. a coupon) lowers the price of billed periods: every discounted period gets a
+negative line with the `label` next to its usage on the same bill, until the discount ends.
+
+```php
+$subscription = $user->subscriptions()->create([
+    'name' => 'Pixel Stream Pass',
+    'unit' => 'month',
+    'price' => 6.714286,
+    'discount' => [
+        'label' => 'SUMMER20',         // shown to the user, e.g. the coupon code
+        'percent_off' => 20,           // or 'amount_off' => 1.50 (net, per period)
+        'duration' => 'repeating',     // once, repeating or forever
+        'duration_in_periods' => 3,    // only for repeating
+    ],
+]);
+
+$subscription->discount;               // {label, percent_off, amount_off, duration, duration_in_periods, periods_remaining}
+```
+
+A period is one unit of the subscription (a month for monthly prices). A free trial isn't a
+billed period: the discount starts with the first paid one. `periods_remaining` counts down with
+every billed period (null for `forever`, 0 once it ended); then `subscription.discount_ended`
+(`EventType::SUBSCRIPTION_DISCOUNT_ENDED`) is sent. A discount can't be combined with a
+`monthly_cap`. It is set when the subscription is created (app subscriptions and checkout
+sessions alike) and changed afterwards with
+[`change()`](#changing-running-subscriptions-trusted-apps). A resize (`predecessor_id`) doesn't
+carry it over: send the successor the rest (`'duration' => 'repeating'`,
+`'duration_in_periods' => $old->discount->periods_remaining`).
 
 ### Webhooks
 
@@ -415,6 +542,35 @@ arrive more than once or out of order: use `$event['id']` to skip duplicates, an
 object through the API when the current state matters. The admin panel can send a
 `webhook.test` event to check your endpoint.
 
+`subscription.renewed` (`EventType::SUBSCRIPTION_RENEWED`) is sent once for every period booked
+on the user's monthly order, **the first one included**, with `$event['data']['period']`:
+`{subscription_id, period_start, period_end, periods, first_period, unit, order_id, order_item_id,
+items, currency_iso, net_amount}` (`net_amount` after a discount). `first_period` is `true` for the
+subscription's first paid period (the checkout, sent after `subscription.activated`, or the first
+period after a free trial) and `false` for every later one (renewals, resuming an expired
+subscription, a unit change applied right away). Hourly subscriptions renew every hour, so this
+event is **opt-in**: select it explicitly for your endpoint, `*` doesn't include it.
+
+```php
+if ($event['type'] === EventType::SUBSCRIPTION_RENEWED) {
+    $period = $event['data']['period'];
+    // e.g. a commission per paid period; the first one may count differently
+    Commission::record($period['subscription_id'], $period['net_amount'], first: $period['first_period']);
+}
+```
+`order.*` events list the order's `items` and `invoice` like
+[app orders](#app-orders-trusted-apps-no-user-token).
+
+`billing_limit.reached` and `billing_limit.available` (`EventType::BILLING_LIMIT_REACHED`,
+`BILLING_LIMIT_AVAILABLE`) tell trusted apps that a user's billing limit was reached or has room
+again; they are opt-in like `subscription.renewed`, see
+[Charges and billing limit](#charges-and-billing-limit-trusted-apps).
+
+`order.refunded` (`EventType::ORDER_REFUNDED`) is sent when money was given back for an order (a
+refund or a partial cancellation, with a credit note); the order carries its `refunds` and
+`refunded_total`. A full refund also cancels the order, so `order.cancelled` is sent too; don't rely on the
+order of the two events.
+
 ### Errors
 
 Every failed request throws `Anikeen\Id\Exceptions\ApiException`, with the user's token as
@@ -425,7 +581,11 @@ well as with the app's (`app*()`). It carries:
   `already_cancelled`), otherwise `null`,
 - `getMessage()`: Anikeen ID's reason,
 - `isNotFound()` (404), `isConflict()` (409) and `isTemporary()` (no response, 429 or 5xx: retry
-  later).
+  later),
+- `isBillingLimitReached()` (409 `billing_limit_reached`: a [charge](#charges-and-billing-limit-trusted-apps)
+  would take the user's monthly bill above their billing limit),
+- `body()`: the error response, for errors with details (e.g. `remaining` of
+  `billing_limit_reached`).
 
 ```php
 use Anikeen\Id\Exceptions\ApiException;
@@ -493,6 +653,11 @@ $subscription = $subscriptions->create([
 
 $subscription->checkout();             // bill the first period
 $subscription->checkout(startsAt: $domain->registered_at); // already running: bill the period that started then
+$subscription->checkout(                // running for longer: also bill the periods that have ended
+    startsAt: $domain->registered_at,
+    billElapsedPeriods: true,
+    maxNetAmount: '15.57',             // net ceiling, e.g. the amount the customer agreed to
+);
 $subscription->pause();                // expires when the paid period ends
 $subscription->resume();               // expired subscriptions start a new period
 $subscription->revoke(refund: false);  // cancel
@@ -505,10 +670,45 @@ The user's Anikeen ID is read from the billable's `anikeen_id` attribute
 (`AnikeenId::useUserIdField('…')` to change it). The app must be trusted by Anikeen ID; it sees the
 subscriptions it created (plus those of clients delegated to it).
 
+#### Starting from an earlier date
+
+`checkout(startsAt: …)` books a service that is already running, e.g. a domain registered before
+the customer came to your app. If the first period from that date is still running, it is billed
+now and renews when it ends. An older start is refused with `period_already_ended`, unless you
+pass `billElapsedPeriods: true` with `maxNetAmount` (net, up to two decimals; both together, or
+`checkout()` throws an `InvalidArgumentException` without sending anything):
+
+- every period that has ended plus the running one is billed now, as one line with the full
+  service period. It lands on the user's collective order of the current month and is invoiced and
+  charged with the next monthly bill; nothing is back-dated.
+- the start may be at most about three years ago (422 otherwise).
+- if the periods come to more than `maxNetAmount`, nothing is booked: 409
+  `elapsed_amount_exceeded`, with the real amount in `$e->body()->net_amount` (e.g. `"20.76"`), so
+  you can show it and retry.
+- 409 `elapsed_periods_not_allowed` when the subscription can't be billed this way (e.g. it ran
+  before, replaces another one, or is billed by the hour or day with a monthly cap).
+
+```php
+try {
+    $subscription->checkout(startsAt: $startsAt, billElapsedPeriods: true, maxNetAmount: $confirmed);
+} catch (ApiException $e) {
+    if ($e->error === 'elapsed_amount_exceeded') {
+        $actual = $e->body()->net_amount; // ask again with the real amount
+    } else {
+        throw $e;
+    }
+}
+```
+
+#### Error codes
+
 Failures throw `Anikeen\Id\Exceptions\ApiException` with `status` (0 = not reachable), a stable
 `error` code (`already_active`, `already_cancelled`, `not_active`, `already_paused`,
 `already_resumed`, `billing_address_missing`, `not_changeable`, `subscription_not_found`,
-`idempotency_key_conflict`) and `isNotFound()`, `isConflict()`, `isTemporary()`:
+`idempotency_key_conflict`, `in_checkout_session`, `trial_already_used`, `proration_not_possible`,
+`credit_exceeds_bill`, `period_already_ended`, `elapsed_periods_not_allowed`,
+`elapsed_amount_exceeded`), the error response via `body()` and `isNotFound()`, `isConflict()`,
+`isTemporary()`:
 
 ```php
 try {
@@ -524,6 +724,70 @@ try {
 }
 ```
 
+### Confirmable orders (trusted apps)
+
+Trusted apps can charge one-off orders right away (`'checkout' => true`). With `'confirm' => true`
+the user confirms and pays the order on Anikeen ID instead, like for a third-party app – e.g. a
+top-up the user starts in your app: Anikeen ID shows the order with VAT, the billing address and
+the payment method (one can be added there) and takes the payment.
+
+```php
+$order = app(AnikeenId::class)->createOrderForUser($team->owner->anikeen_id, [
+    'group' => $team->id,
+    'confirm' => true,
+    'return_url' => route('billing.topup.done'),   // same origin as one of your redirect URIs
+    'metadata' => ['topup' => $topup->id],          // returned as is, also in the order webhooks
+    'items' => [['type' => 'digital', 'name' => 'Credit', 'unit' => 'onetime', 'units' => 1, 'gross_price' => '10.00']],
+])->data;
+
+return redirect()->away($order->confirmation_url);
+// later: https://console.test/billing/topup/done?status=completed&order=01K…
+```
+
+`confirm` needs `items` and can't be combined with `checkout` or a `transaction` (422). The draft
+expires after 24 hours (`expires_at`): it is cancelled, `confirmation_url` becomes null and
+`checkout()` answers 409 `confirmation_expired`. Follow the order through its webhooks:
+`order.created`, then `order.completed` once paid (`order.payment_failed` for a declined charge)
+or `order.cancelled` when the user declines or it expires. `return_url` and `metadata` work for
+every order, also with the user's token (`$user->orders()->create([...])`).
+
+### Changing running subscriptions (trusted apps)
+
+`update()` changes a subscription before its checkout (afterwards only the description).
+`change()` changes price, unit, name, description or discount of a running subscription, like a
+plan change (send only what changes):
+
+```php
+use Anikeen\Id\Resources\AppSubscription;
+
+// upgrade now, prorated: the unused rest of the period is credited, the new price charged for it
+$subscription->change(['apply' => AppSubscription::APPLY_NOW, 'price' => '0.0274', 'name' => 'Cloud Server M']);
+
+// downgrade from the next period on
+$subscription->change(['apply' => AppSubscription::APPLY_PERIOD_END, 'price' => '4.99']);
+$subscription->scheduled_change;       // {applies_at, name, description, unit, price, discount, created_at}
+$subscription->cancelScheduledChange(); // keep the current values after all
+```
+
+- `now` credits the unused part of the current period at the rate it was billed at and charges
+  the rest at the new price, both on the user's open bill. A new `unit` starts a new, fully billed
+  period now. A downgrade whose credit would exceed the open bill is refused with 409
+  `credit_exceeds_bill`: schedule it for the period end instead. 409 `proration_not_possible` when
+  the current period wasn't billed to the subscription (e.g. a takeover); `period_end` works.
+- `period_end` changes nothing now; the next period is billed at the new values. A new
+  `period_end` change replaces the scheduled one, `now` drops it.
+- During a free trial nothing was billed: both just change what the trial ends in.
+- `discount` replaces the discount from the next billed period on, `null` ends it. When the unit
+  changes, a discount that counts in periods or an `amount_off` has to be sent again (422).
+- Subscriptions with a monthly cap change only with `period_end`.
+- Only running subscriptions can change: 409 `not_changeable` for drafts (use `update()`), paused,
+  cancelling, expired and cancelled ones.
+
+When a change takes effect (right away or at the period end), Anikeen ID sends
+`subscription.updated` (`EventType::SUBSCRIPTION_UPDATED`) with the old values of the changed
+fields in `$event['data']['previous_attributes']`. Telling the user about a price increase (and
+getting consent where needed) is up to your app.
+
 ### App orders (trusted apps, no user token)
 
 Orders that bill the app's subscriptions, read with the app's token (scope `orders:client`):
@@ -538,6 +802,188 @@ Each order has `status` (`processing` = current month, still collecting; `pendin
 paid; `completed`; `cancelled`), the totals, `payment_attempts`, `next_payment_attempt_at` (null =
 no more automatic retries) and `last_payment_error`.
 
+Collective (monthly) orders are kept **per app**: your subscriptions are never billed on the same
+order as another app's, even if both use the same `group` (or none); clients delegated to your app
+bill on your app's orders. `$order->oauth_client_id` is the app that bills the order.
+
+Orders also list their lines and their invoice, e.g. to show a team's invoices or to attribute
+amounts (commissions) per subscription:
+
+```php
+$order = app(AnikeenId::class)->appOrders()->find($orderId);
+
+foreach ($order->items as $item) {
+    $item->subscription_id;                     // null for lines that bill no subscription
+    $item->period_start; $item->period_end;     // ISO 8601, the end is exclusive; null without a period
+    $item->net_amount;                          // units × price, rounded to cents
+    $item->discount;                            // {label, percent_off, amount_off} on a discount line, else null
+}
+
+$order->invoice;                                // null until paid, then {id, number, status, …, pdf_url}
+$pdf = app(AnikeenId::class)->appOrders()->invoicePdf($orderId); // the invoice PDF (binary)
+```
+
+The net amount actually billed for a subscription is the sum of `net_amount` of its lines
+(discount lines are negative). `invoicePdf()` throws `ApiException` with 404 `invoice_not_found`
+before the order is paid and 409 `invoice_not_ready` while the PDF is still being rendered
+(usually seconds after the payment; try again later). Legacy orders from before collective orders
+were kept per app (`oauth_client_id` null) can also bill other apps' subscriptions: there `items`
+lists only your lines (the totals are the whole order's), `invoice->pdf_url` is null and
+`invoicePdf()` throws `ApiException` with 403 `invoice_includes_other_apps`.
+
+### Billing portal links (trusted apps)
+
+A "Manage billing" button for a user whose token your app doesn't have (e.g. the owner of a team
+your app bills): create a link to the user's billing pages on Anikeen ID with the app's token
+(scope `subscriptions:client` or `orders:client`). Like Stripe's customer portal, it works
+**without a login**:
+
+```php
+Route::post('teams/{team}/billing', function (Team $team) {
+    return redirect()->away($team->owner->appBillingPortalUrl([
+        'return_url' => route('teams.show', $team), // "Back to <app>"; same origin as one of your redirect URIs
+        'group' => $team->id,                       // only this group's subscriptions, orders and invoices
+        'flow' => 'invoices',                       // overview (default), payment_method, payment_method_update,
+                                                    // invoices, subscriptions or orders
+    ]));
+});
+
+app(AnikeenId::class)->createBillingPortalLinkForUser($userId, ['flow' => 'payment_method_update']);
+// {object: "billing_portal_link", url, user_id, flow, group, return_url, expires_at}
+```
+
+The link is **single use** and valid for about 15 minutes: create it when the user clicks and
+redirect right away; don't store, mail or reuse it (a second request with the same link, e.g. a
+reload, gets a 403). Opening it starts a portal session for that user that needs no login and
+signs nobody in: only the billing pages of the `flow`, only what bills your app's subscriptions
+(of the `group`), with "Back to *app*". The user's account settings, other apps and OAuth consent
+stay behind the normal login; signed in as another account, the portal still shows only the
+link's user. The session ends after an hour without activity or on "Back to *app*".
+`payment_method_update` leads straight to replacing the payment method (e.g. after a failed
+payment) and back to `return_url`. For the signed-in user with their own token,
+`$user->billingPortalUrl()` stays available.
+
+### Charges and billing limit (trusted apps)
+
+Trusted apps can book single items onto a user's **open monthly bill** of the app, e.g. each item
+a shipping app sends: one line per charge, no subscription, charged with the bill on the 1st like
+every other line (invoice and VAT by Anikeen ID). Anikeen has to enable charging for your app and
+sets a maximum per charge; the user must be connected to your app (they authorised it, or your app
+bills them through subscriptions or orders).
+
+```php
+$anikeen = app(AnikeenId::class);
+
+$charge = $anikeen->createChargeForUser($user->anikeen_id, [
+    'idempotency_key' => "shipment-{$shipment->id}", // per app and user: a retry returns the same charge
+    'name' => 'Signed card',                         // the line on the bill
+    'type' => 'physical',                            // digital (default), physical, physical-reduced
+    'quantity' => 2,
+    'unit_price' => '4.00',                          // net per piece, up to 6 decimals
+    'reference' => "order-{$shipment->order_id}",    // your own id; not on the bill
+    // 'group' => $team->id,                         // only a group your app already bills the user in
+    // 'occurred_at' => '2026-11-05T14:00:00Z',      // the service date, at most 31 days ago
+]);
+
+$charge->id();          // keep it to void the charge later
+$charge->grossAmount(); // "9.52": what it added to the bill
+$charge->orderId();     // the monthly bill it is on
+$charge->status();      // open, billed (the bill was closed) or voided
+
+$anikeen->findChargeForUser($user->anikeen_id, $chargeId);
+$anikeen->voidChargeForUser($user->anikeen_id, $chargeId, 'Parcel lost'); // while the bill is open
+```
+
+- **Idempotency:** retrying with the same key and the same fields returns the existing charge
+  (200 instead of 201), also after the limit was reached; the same key with other fields is 409
+  `idempotency_key_conflict` (`charge_id` in `body()`). Use one key per item you charge for.
+- **Voiding** removes the line while the bill is open (an already voided charge is returned as
+  it is). Once the bill was closed: 409 `charge_already_billed`; only a refund of the order by
+  Anikeen credits it.
+- **`group`** is null or a group your app already bills the user in (a running subscription or an
+  open monthly bill of your app); others are refused with 409 `group_not_allowed`.
+- `reference` and `metadata` (up to 20 string values) are your data about the user, kept with the
+  charge and not shown on the bill: put nothing sensitive there.
+
+**Billing limit.** A user can set one monthly limit (gross) for their whole open monthly bill
+across all Anikeen services. A charge that would take the bill above it is refused with 409
+`billing_limit_reached`; exactly reaching the limit is allowed, `0.00` refuses every charge.
+Subscription renewals and usage are still billed, so the bill can end above the limit. Read the
+limit to stop offering paid actions early (advisory only, it reserves nothing):
+
+```php
+$limit = $anikeen->billingLimitForUser($user->anikeen_id);
+
+$limit->hasLimit();     // false: no limit, every charge fits
+$limit->isReached();    // used >= limit: start no new paid service
+$limit->remaining();    // "17.60" gross room left, null without a limit
+$limit->remainingNet(); // "14.78" at the user's VAT rate, a hint
+$limit->allows('9.52'); // would this charge fit right now (advisory)
+$limit->resetsAt();     // when this month's bills are closed
+$limit->version();      // only goes up
+$limit->used();         // the user's open bills across all Anikeen services, null without a limit
+$limit->usedByApp();    // your app's share; used − usedByApp = "your other Anikeen services"
+```
+
+`used` (the user's open bills across all Anikeen services) is visible to apps **only while the
+user has set a limit**; without one `limit`, `used`, `remaining` and `remaining_net` are null.
+`usedByApp()` (your app's own open bills) is always there. The user sees their own limit in
+`$user->billingOverview()->billing_limit` (with `used`, without `used_by_app`; null while they
+can't set one). Apps that may charge can read the limit; others need Anikeen to allow it (403
+`billing_limit_not_enabled`).
+
+Handling a refused charge:
+
+```php
+use Anikeen\Id\Exceptions\ApiException;
+
+try {
+    $charge = $anikeen->createChargeForUser($user->anikeen_id, $attributes);
+} catch (ApiException $e) {
+    if ($e->isBillingLimitReached()) {
+        $e->body()->remaining;  // room left before this charge, e.g. "2.60"
+        $e->body()->required;   // the refused charge, gross
+        $e->body()->resets_at;  // when the limit has room again at the latest
+        return $shipment->holdForBillingLimit();
+    }
+
+    match ($e->error) {
+        'charge_exceeds_maximum' => report($e),   // above your app's maximum ($e->body()->max_charge_net)
+        'group_not_allowed' => report($e),
+        'billing_address_missing' => $shipment->askForBillingAddress(),
+        default => throw $e,
+    };
+}
+```
+
+**Webhooks.** `billing_limit.reached` and `billing_limit.available` are sent when the limit is
+reached or has room again (a raised or removed limit, a void, the monthly reset). They are
+**opt-in** (select them for your endpoint; `*` doesn't include them) and go only to apps that may
+read the limit of a user connected to them. `data.object` is the billing limit as your app reads
+it, `data.reason` says why (`booking`, `limit_changed`, `limit_removed`, `voided`,
+`period_reset`, `order_changed`). Keep the highest `version` per user and ignore events with a
+lower or equal one, so a late delivery can't undo a newer state. In the `match` of the
+[webhook route](#webhooks):
+
+```php
+EventType::BILLING_LIMIT_REACHED, EventType::BILLING_LIMIT_AVAILABLE => Customer::syncBillingLimit(
+    $object['user_id'], reached: $event['type'] === EventType::BILLING_LIMIT_REACHED, version: $object['version'],
+),
+```
+
+The limit is checked live when a charge is booked, so a late or missed webhook never lets a
+charge through; poll `billingLimitForUser()` if you need the current state.
+
+#### Error codes
+
+| Status | `error` |
+|--------|---------|
+| 403 | `client_not_allowed` (not a trusted app with its own token), `charges_not_enabled` (charging is not enabled for your app; also for reads and voids), `billing_limit_not_enabled` (limit read only) |
+| 404 | `user_not_found` (unknown, deleted or not connected to your app), `charge_not_found` |
+| 409 | `billing_limit_reached` (`isBillingLimitReached()`), `charge_exceeds_maximum` (+ `max_charge_net`), `group_not_allowed`, `idempotency_key_conflict` (+ `charge_id`), `billing_address_missing`, `charge_already_billed` (+ `charge_id`) |
+| 422 | validation (`errors`), no `error` code |
+| 429 | `too_many_requests` (`isTemporary()`) |
+
 ### Checkout sessions (the user confirms several subscriptions at once)
 
 Instead of checking subscriptions out itself, an app can let the user confirm them on Anikeen ID,
@@ -595,6 +1041,179 @@ While a session is open, its subscriptions can't be checked out or repriced by t
 `subscription.activated` / `subscription.cancelled` are still sent per subscription, before the
 `checkout.*` event of the session.
 
+### User accounts (trusted apps, no user token)
+
+Trusted apps can look up and create Anikeen ID accounts with the app's own token. Email addresses
+are matched regardless of case.
+
+```php
+$anikeenId = app(AnikeenId::class);
+
+$account = $anikeenId->findUserByEmail('erika@example.com'); // null if no account uses it
+$account?->data->id;                   // also name, email, email_verified, has_billing_address
+
+$result = $anikeenId->createUser([     // finds the account of the email address or creates it
+    'name' => 'Erika Mustermann',
+    'email' => 'erika@example.com',
+    'send_invitation' => true,         // a new account gets a mail with a link to set a password
+]);
+$result->data->created;                // false: the account already existed (and is unchanged)
+$result->data->invitation_sent;        // only for an account created by this call without a password
+```
+
+`findUserByEmail()` changes nothing. It throws `ApiException` when the request fails for any reason
+other than an unknown address.
+
+
+## Preferences
+
+Anikeen ID keeps small per-user settings as JSON values under a *namespace* and a *key*, so they
+follow the user across devices and apps:
+
+- **`global`** is shared by all apps. Only registered keys and values are accepted: today
+  `SharedPreference::APPEARANCE` with `Appearance::SYSTEM`, `LIGHT` or `DARK`.
+- **App namespaces** (e.g. `acme`) hold one app's own data: onboarding state, a default workspace,
+  the user's customer ID at a payment provider. Use another namespace on staging (e.g.
+  `acme-staging`), so test data never mixes with production.
+
+**Registration.** Access never comes from scopes alone: any client can request any scope. Ask
+Anikeen to register your OAuth client(s) (the app has to be [trusted](#trusted-apps)) for
+
+- the namespaces your app owns (read, write and the lookup),
+- read access to another app's namespace,
+- `global` with the app's token (users always read and write their own `global` with their token),
+- keys whose values are unique (see the lookup below).
+
+Without it, app requests fail with 403 `client_not_trusted` or 404 `namespace_not_found`.
+
+**Scopes.** User tokens need `Scope::PREFERENCES` (`preferences`, read and write) or
+`Scope::PREFERENCES_READ` (`preferences:read`); app tokens `Scope::PREFERENCES_CLIENT`
+(`preferences:client`).
+
+**Limits.** A value is at most 2048 bytes of JSON and 4 levels deep; at most 50 keys per user and
+namespace (updating a key always works); keys match `^[a-z][a-z0-9_]{0,63}$`. Per minute: 60
+requests per user and app with user tokens, 600 per app with the app token and 120 lookups per
+app (429 `rate_limited` with `Retry-After`).
+
+**Not a secrets store.** Values are stored as plain JSON and shown to Anikeen's support and to the
+user on a request for their data. Store IDs and settings, never passwords, API keys or tokens: keys
+that look like credentials (`secret`, `token`, `password`, `api_key`, …) are rejected with 422
+`forbidden_key`.
+
+### The user's shared preferences (user token)
+
+```php
+use Anikeen\Id\Enums\Appearance;
+use Anikeen\Id\Enums\SharedPreference;
+
+$user->globalPreference(SharedPreference::APPEARANCE, Appearance::SYSTEM); // the default when not set
+$user->globalPreferences()->values();     // ['appearance' => 'dark']
+
+$preference = $user->setGlobalPreference(SharedPreference::APPEARANCE, Appearance::DARK);
+$preference->version;                     // e.g. 1042
+
+$user->deleteGlobalPreference(SharedPreference::APPEARANCE);
+```
+
+User tokens reach `global` only; an app namespace answers 404 `namespace_not_found`, whatever the
+token's scopes. The app's own token (client credentials) has no user and gets 401 on these routes.
+
+### Preferences of any user (trusted apps)
+
+With the app's own token, by the user's Anikeen ID:
+
+```php
+$anikeenId = app(AnikeenId::class);
+
+$preferences = $anikeenId->preferencesByUserId($userId, 'acme'); // sorted by key, no pagination
+$preferences->get('onboarding', []);     // the value or a default; also has(), find(), values()
+
+$preference = $anikeenId->preferenceByUserId($userId, 'acme', 'onboarding'); // 404 preference_not_found if not set
+$preference->value;                      // JSON objects as stdClass, so {} stays {}
+$preference->version;
+$preference->updated_by;                 // {type: "user"|"app", client_id}
+
+$anikeenId->setPreferenceByUserId($userId, 'acme', 'onboarding', ['step' => 3]);
+$anikeenId->deletePreferenceByUserId($userId, 'acme', 'onboarding');
+```
+
+A value is any JSON value; pass `(object) []` for an empty object (`[]` is an empty list).
+`setPreferenceByUserId()` returns the stored preference; `wasCreated()` tells whether the write
+created the key. A deleted user's preferences are gone: every call answers 404 `user_not_found`.
+
+### Conditional writes and retries
+
+Writes are *last write wins* by default. Every write gives the preference a new `version`.
+Versions are opaque: they only go up (also when a key is deleted and set again) and increase per
+user, not by one per key. Pass the version you read to write only if nobody changed it in between
+(`If-Match`), or `createOnly` to write only if the key isn't set yet (`If-None-Match: *`):
+
+```php
+use Anikeen\Id\Exceptions\PreconditionFailedException;
+
+$preference = $anikeenId->preferenceByUserId($userId, 'acme', 'layout');
+
+try {
+    $anikeenId->setPreferenceByUserId($userId, 'acme', 'layout', $merged, ifVersion: $preference->version);
+} catch (PreconditionFailedException $e) {
+    $e->error;            // "preference_version_mismatch" (or "preference_exists" for createOnly)
+    $e->currentVersion(); // the version stored now, null when the key isn't set: reload, merge, retry
+}
+
+$anikeenId->setPreferenceByUserId($userId, 'acme', 'welcome_sent_at', now()->toIso8601String(), createOnly: true);
+```
+
+`deletePreferenceByUserId()`, `setGlobalPreference()` and `deleteGlobalPreference()` take
+`ifVersion` too. Writing the value that is already stored is a no-op that succeeds (no new version),
+even when the precondition would fail, so retrying a write after a timeout is safe.
+
+### Unique keys and the lookup
+
+Anikeen can declare keys of your namespace unique, e.g. `customer_id`. Their values are strings of
+1 to 255 characters without surrounding whitespace, held by at most one user: setting another
+user's value fails with 409 `preference_value_taken`. Your app can then find the user by value, e.g.
+in a payment provider's webhook:
+
+```php
+$userId = $anikeenId->findUserIdByPreference('acme', 'customer_id', 'cus_123'); // null if nobody holds it
+```
+
+The value is sent in the body, never in the URL. `findUserIdByPreference()` returns `null` only for
+404 `preference_not_found` (also when the user was deleted); everything else throws, e.g. 422
+`key_not_unique` for a key that isn't declared unique.
+
+### Error codes
+
+Failures throw `ApiException` (412 `PreconditionFailedException`) with these `error` codes:
+
+| Status | `error` |
+|--------|---------|
+| 401 | `unauthenticated` (no or an invalid token; an app token on the user routes) |
+| 403 | `missing_scope`, `app_token_required` (a user token on the app routes), `client_not_trusted`, `namespace_read_only`, `lookup_not_allowed` |
+| 404 | `namespace_not_found` (unknown or not accessible), `user_not_found` (also deleted users), `preference_not_found`, `not_found` |
+| 405 | `method_not_allowed` |
+| 409 | `preference_value_taken` |
+| 412 | `preference_version_mismatch`, `preference_exists` |
+| 422 | `invalid_key`, `forbidden_key`, `unknown_shared_key`, `value_required`, `value_too_large`, `value_too_deep`, `invalid_shared_value`, `invalid_unique_value`, `key_not_unique`, `preference_limit_exceeded` |
+| 429 | `rate_limited` |
+
+A `null` value is rejected with 422 `value_required`: delete the key instead.
+
+### Caching
+
+Anikeen ID is the source of truth. `globalPreferences()` and `globalPreference()` cache the list
+on the model instance (one request per instance); `setGlobalPreference()` and
+`deleteGlobalPreference()` clear it. For a copy that outlives the request, keep a read cache: fill
+it at sign-in, write to Anikeen ID first and update the copy from the response, and let it expire
+after about an hour, since other apps and the user can change shared preferences too:
+
+```php
+$appearance = Cache::remember("appearance:{$user->id}", now()->addHour(),
+    fn () => $user->globalPreference(SharedPreference::APPEARANCE, Appearance::SYSTEM));
+
+$user->setGlobalPreference(SharedPreference::APPEARANCE, $request->appearance);
+Cache::put("appearance:{$user->id}", $request->appearance, now()->addHour());
+```
 
 ## API authentication
 
@@ -762,6 +1381,16 @@ AnikeenId::withToken('abcdef123456')->getAuthedUser();
 public function retrievingToken(string $grantType, array $attributes): Result
 ```
 
+### ManagesPreferences
+
+```php
+public function preferencesByUserId(string $userId, string $namespace): Preferences
+public function preferenceByUserId(string $userId, string $namespace, string $key): Preference
+public function setPreferenceByUserId(string $userId, string $namespace, string $key, mixed $value, ?int $ifVersion = null, bool $createOnly = false): Preference
+public function deletePreferenceByUserId(string $userId, string $namespace, string $key, ?int $ifVersion = null): void
+public function findUserIdByPreference(string $namespace, string $key, string $value): ?string
+```
+
 ### ManagesPricing
 
 ```php
@@ -791,8 +1420,13 @@ public function shippingPriceList(): Result
 ```php
 public function appOrders(): AppOrders
 public function appCheckoutSessions(): AppCheckoutSessions
+public function createBillingPortalLinkForUser(string $userId, array $attributes = []): object
 public function createOrderForUser(string $userId, array $attributes): Result
 public function createTransactionForUser(string $userId, array $attributes): Result
+public function createChargeForUser(string $userId, array $attributes): AppCharge
+public function findChargeForUser(string $userId, string $chargeId): AppCharge
+public function voidChargeForUser(string $userId, string $chargeId, ?string $reason = null): AppCharge
+public function billingLimitForUser(string $userId): BillingLimit
 ```
 
 ### ManagesSocialiteUsers
@@ -812,6 +1446,7 @@ public function sshKeysByUserId(string $userId): SshKeys
 ```php
 public function getAuthedUser(): Result
 public function createUser(array $attributes): Result
+public function findUserByEmail(string $email): ?Result
 public function findOrCreateSocialiteUser(string $provider, string $providerId, ?string $email = null, ?string $name = null): Result
 public function refreshToken(string $storedRefreshToken, string $scope = ''): Result
 public function isEmailExisting(string $email): Result
@@ -896,6 +1531,7 @@ public function appSubscriptions(): AppSubscriptions
 public function appCheckoutSessions(): AppCheckoutSessions
 public function checkoutSessions(): CheckoutSessions
 public function appOrders(): AppOrders
+public function appBillingPortalUrl(array $attributes = []): string
 public function setBillable(Billable|Model $billable): self
 public function getBillable(): Billable
 ```
@@ -916,6 +1552,15 @@ public function setBillable(Billable|Model $billable): self
 public function getBillable(): Billable
 ```
 
+### ManagesUserPreferences
+
+```php
+public function globalPreferences(): Preferences
+public function globalPreference(string $key, mixed $default = null): mixed
+public function setGlobalPreference(string $key, mixed $value, ?int $ifVersion = null): Preference
+public function deleteGlobalPreference(string $key, ?int $ifVersion = null): void
+```
+
 ### ManagesUserSshKeys
 
 ```php

README.stub

@@ -4,7 +4,7 @@
 [![Total Downloads](https://img.shields.io/packagist/dt/anikeen/id.svg?style=flat-square)](https://packagist.org/packages/anikeen/id)
 [![License](https://img.shields.io/packagist/l/anikeen/id.svg?style=flat-square)](https://packagist.org/packages/anikeen/id)
 
-PHP Anikeen ID API Client for Laravel 11+
+PHP Anikeen ID API Client for Laravel 12+
 
 Sign in with Anikeen ID and let your users pay with their Anikeen ID account: one-off orders,
 subscriptions and physical goods, with invoices, VAT and payment handled by Anikeen ID.
@@ -16,11 +16,12 @@ subscriptions and physical goods, with invoices, VAT and payment handled by Anik
 3. [Sign in with Anikeen ID](#sign-in-with-anikeen-id)
 4. [Payments](#payments)
 5. [Trusted apps](#trusted-apps)
-6. [API authentication](#api-authentication)
+6. [Preferences](#preferences)
-7. [General](#general)
+7. [API authentication](#api-authentication)
-8. [Examples](#examples)
+8. [General](#general)
-9. [Documentation](#documentation)
+9. [Examples](#examples)
-10. [Development](#development)
+10. [Documentation](#documentation)
+11. [Development](#development)
 
 ## Installation
 
@@ -71,7 +72,7 @@ Add to `config/services.php` file:
 
 ### Event Listener
 
-In Laravel 11, the default EventServiceProvider provider was removed. Instead, add the listener using the listen method on the Event facade, in your `AppServiceProvider` boot method:
+Since Laravel 11, the default EventServiceProvider provider was removed. Instead, add the listener using the listen method on the Event facade, in your `AppServiceProvider` boot method:
 
 ```php
 public function boot(): void
@@ -160,6 +161,35 @@ if ($result->success()) {
 }
 ```
 
+### Scopes
+
+Scopes follow one schema: `resource` grants full access, `resource:read` read-only access and
+`resource:client` access to what the app or token created itself. All of them are constants on
+`Anikeen\Id\Enums\Scope`, e.g. `Scope::ORDERS_READ`.
+
+The Anikeen Console accepts personal access tokens and OAuth tokens (no client credentials) with
+these scopes for its product and reseller APIs:
+
+| Scope | Constant | Grants |
+|-------|----------|--------|
+| `products:read` | `Scope::PRODUCTS_READ` | view the products of your teams |
+| `reseller-customers:read` | `Scope::RESELLER_CUSTOMERS_READ` | view a reseller team's customers and invitations |
+| `reseller-customers` | `Scope::RESELLER_CUSTOMERS` | manage customers: invite, resend, remove logins (includes reading) |
+| `reseller-grants` | `Scope::RESELLER_GRANTS` | grant customers access to products and revoke it |
+| `reseller-orders` | `Scope::RESELLER_ORDERS` | order products for customers, charged right away |
+
+A full reseller scope includes reading. `user` and `*` do not open the reseller endpoints: the
+token has to carry the reseller scope itself. For the product APIs there is only `products:read`;
+changing products needs `user`.
+
+Anikeen ID's [preferences](#preferences) use these scopes:
+
+| Scope | Constant | Grants |
+|-------|----------|--------|
+| `preferences:read` | `Scope::PREFERENCES_READ` | read the user's shared preferences (`global`) |
+| `preferences` | `Scope::PREFERENCES` | read and change them |
+| `preferences:client` | `Scope::PREFERENCES_CLIENT` | app tokens: the preferences of any user, in the namespaces Anikeen registered for the app |
+
 ### Change the default access token / refresh token field name
 
 If your access / refresh token fields differ from the default `anikeen_id_access_token` / `anikeen_id_refresh_token`, you can specify the field name in the `AppServiceProvider` boot method:
@@ -184,11 +214,14 @@ public function boot(): void
 | Something that recurs (a pass, a plan) | [Subscriptions](#subscriptions) | user | the user, on Anikeen ID |
 | Several subscriptions in one step | [Checkout sessions](#checkout-sessions-the-user-confirms-several-subscriptions-at-once) | user or app | the user, on Anikeen ID |
 | Usage billing from your backend, without the user online | [App subscriptions](#app-subscriptions-trusted-apps-no-user-token) | app | your app (trusted apps only) |
+| Single items on the user's monthly bill (e.g. a shipped item) | [Charges](#charges-and-billing-limit-trusted-apps) | app | your app (trusted apps only) |
 
 Most apps are third-party apps: they create an order or subscription as a draft, send the user to
 Anikeen ID to confirm and pay, and get the user back afterwards. Anikeen ID shows the items, asks
 for missing addresses, takes the payment and writes the invoice. Trusted apps (operated by
-Anikeen) can also charge directly; see [Trusted apps](#trusted-apps).
+Anikeen) can also charge directly; see [Trusted apps](#trusted-apps). For a per-item charge on
+the user's monthly bill use `createChargeForUser()`, not `createOrderForUser()`: an order is a
+separate one-off purchase, charged on its own.
 
 The flow, as in a typical shop:
 
@@ -361,8 +394,102 @@ same value as `status`):
 | `expired` | Paused and ran out; `resume()` starts a new period | no |
 | `cancelled` | Cancelled for good | no |
 
-There are shortcuts for each: `isDraft()`, `isPaused()`, `isCancelling()`, `isExpired()`,
+There are shortcuts for each: `isDraft()`, `isTrial()`, `isPaused()`, `isCancelling()`,
-`isCancelled()`. App subscriptions (`appSubscriptions()`) have the same methods.
+`isExpired()`, `isCancelled()`. App subscriptions (`appSubscriptions()`) have the same methods.
+
+#### Free trials
+
+Give a subscription a free trial with `trial_days` (1–365, counted from the user's confirmation or
+the checkout) or a fixed `trial_ends_at` (ISO 8601, in the future), not both. The subscription
+starts right away with `status` `trial` and nothing billed; the first period is billed when the
+trial ends. `trial_once` refuses the trial if the user already had one with your app in the same
+`group` (422 when creating, 409 `trial_already_used` when checking out):
+
+```php
+$subscription = $user->subscriptions()->create([
+    'name' => 'Pixel Stream Pass',
+    'unit' => 'month',
+    'price' => 6.714286,
+    'trial_days' => 14,
+    'trial_once' => true,
+]);
+```
+
+A few days before the trial ends, Anikeen ID sends `subscription.trial_will_end`
+(`EventType::SUBSCRIPTION_TRIAL_WILL_END`), e.g. to remind the user; `data.payment_method_missing`
+tells you whether the user still has to add a payment method. Cancelling during the trial
+bills nothing. Trials work the same for app subscriptions and per subscription of a checkout
+session.
+
+By default the user needs a payment method to confirm a trial. With `trial_payment_method`
+`TrialPaymentMethod::OPTIONAL` (only together with a trial; `TrialPaymentMethod::REQUIRED` is the
+default) the user can confirm it without one, as long as nothing else has to be paid: in a
+checkout session every subscription has to be such a trial. The confirmation page tells the user
+to add a payment method before the trial ends. If there is still none then, the subscription is
+**cancelled** at the trial's end instead of billed: `status` `cancelled`, `cancellation_reason`
+`CancellationReason::TRIAL_ENDED_WITHOUT_PAYMENT_METHOD`, `subscription.cancelled` with
+`data.reason` set to the same value, and no `subscription.renewed`. Adding a payment method later
+doesn't bring it back – create a new subscription. The trial still counts for `trial_once`.
+Anikeen ID also mails the user a few days before such a trial ends without a payment method.
+
+```php
+use Anikeen\Id\Enums\CancellationReason;
+use Anikeen\Id\Enums\TrialPaymentMethod;
+use Anikeen\Id\Webhooks\EventType;
+
+$subscription = $user->appSubscriptions()->create([
+    'group' => $teamId,
+    'name' => 'Uptimr Pro',
+    'unit' => 'month',
+    'price' => 19.00,
+    'trial_days' => 14,
+    'trial_payment_method' => TrialPaymentMethod::OPTIONAL,
+]);
+
+// in your webhook handler
+$data = $event['data'];
+
+match ($event['type']) {
+    EventType::SUBSCRIPTION_TRIAL_WILL_END => $data['payment_method_missing']
+        ? Reminder::addPaymentMethod($data['object']['id'])
+        : null,
+    EventType::SUBSCRIPTION_CANCELLED => $data['reason'] === CancellationReason::TRIAL_ENDED_WITHOUT_PAYMENT_METHOD
+        ? Pass::downgrade($data['object']['id'])
+        : Pass::revoke($data['object']['id']),
+    default => null,
+};
+```
+
+#### Discounts
+
+A `discount` (e.g. a coupon) lowers the price of billed periods: every discounted period gets a
+negative line with the `label` next to its usage on the same bill, until the discount ends.
+
+```php
+$subscription = $user->subscriptions()->create([
+    'name' => 'Pixel Stream Pass',
+    'unit' => 'month',
+    'price' => 6.714286,
+    'discount' => [
+        'label' => 'SUMMER20',         // shown to the user, e.g. the coupon code
+        'percent_off' => 20,           // or 'amount_off' => 1.50 (net, per period)
+        'duration' => 'repeating',     // once, repeating or forever
+        'duration_in_periods' => 3,    // only for repeating
+    ],
+]);
+
+$subscription->discount;               // {label, percent_off, amount_off, duration, duration_in_periods, periods_remaining}
+```
+
+A period is one unit of the subscription (a month for monthly prices). A free trial isn't a
+billed period: the discount starts with the first paid one. `periods_remaining` counts down with
+every billed period (null for `forever`, 0 once it ended); then `subscription.discount_ended`
+(`EventType::SUBSCRIPTION_DISCOUNT_ENDED`) is sent. A discount can't be combined with a
+`monthly_cap`. It is set when the subscription is created (app subscriptions and checkout
+sessions alike) and changed afterwards with
+[`change()`](#changing-running-subscriptions-trusted-apps). A resize (`predecessor_id`) doesn't
+carry it over: send the successor the rest (`'duration' => 'repeating'`,
+`'duration_in_periods' => $old->discount->periods_remaining`).
 
 ### Webhooks
 
@@ -415,6 +542,35 @@ arrive more than once or out of order: use `$event['id']` to skip duplicates, an
 object through the API when the current state matters. The admin panel can send a
 `webhook.test` event to check your endpoint.
 
+`subscription.renewed` (`EventType::SUBSCRIPTION_RENEWED`) is sent once for every period booked
+on the user's monthly order, **the first one included**, with `$event['data']['period']`:
+`{subscription_id, period_start, period_end, periods, first_period, unit, order_id, order_item_id,
+items, currency_iso, net_amount}` (`net_amount` after a discount). `first_period` is `true` for the
+subscription's first paid period (the checkout, sent after `subscription.activated`, or the first
+period after a free trial) and `false` for every later one (renewals, resuming an expired
+subscription, a unit change applied right away). Hourly subscriptions renew every hour, so this
+event is **opt-in**: select it explicitly for your endpoint, `*` doesn't include it.
+
+```php
+if ($event['type'] === EventType::SUBSCRIPTION_RENEWED) {
+    $period = $event['data']['period'];
+    // e.g. a commission per paid period; the first one may count differently
+    Commission::record($period['subscription_id'], $period['net_amount'], first: $period['first_period']);
+}
+```
+`order.*` events list the order's `items` and `invoice` like
+[app orders](#app-orders-trusted-apps-no-user-token).
+
+`billing_limit.reached` and `billing_limit.available` (`EventType::BILLING_LIMIT_REACHED`,
+`BILLING_LIMIT_AVAILABLE`) tell trusted apps that a user's billing limit was reached or has room
+again; they are opt-in like `subscription.renewed`, see
+[Charges and billing limit](#charges-and-billing-limit-trusted-apps).
+
+`order.refunded` (`EventType::ORDER_REFUNDED`) is sent when money was given back for an order (a
+refund or a partial cancellation, with a credit note); the order carries its `refunds` and
+`refunded_total`. A full refund also cancels the order, so `order.cancelled` is sent too; don't rely on the
+order of the two events.
+
 ### Errors
 
 Every failed request throws `Anikeen\Id\Exceptions\ApiException`, with the user's token as
@@ -425,7 +581,11 @@ well as with the app's (`app*()`). It carries:
   `already_cancelled`), otherwise `null`,
 - `getMessage()`: Anikeen ID's reason,
 - `isNotFound()` (404), `isConflict()` (409) and `isTemporary()` (no response, 429 or 5xx: retry
-  later).
+  later),
+- `isBillingLimitReached()` (409 `billing_limit_reached`: a [charge](#charges-and-billing-limit-trusted-apps)
+  would take the user's monthly bill above their billing limit),
+- `body()`: the error response, for errors with details (e.g. `remaining` of
+  `billing_limit_reached`).
 
 ```php
 use Anikeen\Id\Exceptions\ApiException;
@@ -493,6 +653,11 @@ $subscription = $subscriptions->create([
 
 $subscription->checkout();             // bill the first period
 $subscription->checkout(startsAt: $domain->registered_at); // already running: bill the period that started then
+$subscription->checkout(                // running for longer: also bill the periods that have ended
+    startsAt: $domain->registered_at,
+    billElapsedPeriods: true,
+    maxNetAmount: '15.57',             // net ceiling, e.g. the amount the customer agreed to
+);
 $subscription->pause();                // expires when the paid period ends
 $subscription->resume();               // expired subscriptions start a new period
 $subscription->revoke(refund: false);  // cancel
@@ -505,10 +670,45 @@ The user's Anikeen ID is read from the billable's `anikeen_id` attribute
 (`AnikeenId::useUserIdField('…')` to change it). The app must be trusted by Anikeen ID; it sees the
 subscriptions it created (plus those of clients delegated to it).
 
+#### Starting from an earlier date
+
+`checkout(startsAt: …)` books a service that is already running, e.g. a domain registered before
+the customer came to your app. If the first period from that date is still running, it is billed
+now and renews when it ends. An older start is refused with `period_already_ended`, unless you
+pass `billElapsedPeriods: true` with `maxNetAmount` (net, up to two decimals; both together, or
+`checkout()` throws an `InvalidArgumentException` without sending anything):
+
+- every period that has ended plus the running one is billed now, as one line with the full
+  service period. It lands on the user's collective order of the current month and is invoiced and
+  charged with the next monthly bill; nothing is back-dated.
+- the start may be at most about three years ago (422 otherwise).
+- if the periods come to more than `maxNetAmount`, nothing is booked: 409
+  `elapsed_amount_exceeded`, with the real amount in `$e->body()->net_amount` (e.g. `"20.76"`), so
+  you can show it and retry.
+- 409 `elapsed_periods_not_allowed` when the subscription can't be billed this way (e.g. it ran
+  before, replaces another one, or is billed by the hour or day with a monthly cap).
+
+```php
+try {
+    $subscription->checkout(startsAt: $startsAt, billElapsedPeriods: true, maxNetAmount: $confirmed);
+} catch (ApiException $e) {
+    if ($e->error === 'elapsed_amount_exceeded') {
+        $actual = $e->body()->net_amount; // ask again with the real amount
+    } else {
+        throw $e;
+    }
+}
+```
+
+#### Error codes
+
 Failures throw `Anikeen\Id\Exceptions\ApiException` with `status` (0 = not reachable), a stable
 `error` code (`already_active`, `already_cancelled`, `not_active`, `already_paused`,
 `already_resumed`, `billing_address_missing`, `not_changeable`, `subscription_not_found`,
-`idempotency_key_conflict`) and `isNotFound()`, `isConflict()`, `isTemporary()`:
+`idempotency_key_conflict`, `in_checkout_session`, `trial_already_used`, `proration_not_possible`,
+`credit_exceeds_bill`, `period_already_ended`, `elapsed_periods_not_allowed`,
+`elapsed_amount_exceeded`), the error response via `body()` and `isNotFound()`, `isConflict()`,
+`isTemporary()`:
 
 ```php
 try {
@@ -524,6 +724,70 @@ try {
 }
 ```
 
+### Confirmable orders (trusted apps)
+
+Trusted apps can charge one-off orders right away (`'checkout' => true`). With `'confirm' => true`
+the user confirms and pays the order on Anikeen ID instead, like for a third-party app – e.g. a
+top-up the user starts in your app: Anikeen ID shows the order with VAT, the billing address and
+the payment method (one can be added there) and takes the payment.
+
+```php
+$order = app(AnikeenId::class)->createOrderForUser($team->owner->anikeen_id, [
+    'group' => $team->id,
+    'confirm' => true,
+    'return_url' => route('billing.topup.done'),   // same origin as one of your redirect URIs
+    'metadata' => ['topup' => $topup->id],          // returned as is, also in the order webhooks
+    'items' => [['type' => 'digital', 'name' => 'Credit', 'unit' => 'onetime', 'units' => 1, 'gross_price' => '10.00']],
+])->data;
+
+return redirect()->away($order->confirmation_url);
+// later: https://console.test/billing/topup/done?status=completed&order=01K…
+```
+
+`confirm` needs `items` and can't be combined with `checkout` or a `transaction` (422). The draft
+expires after 24 hours (`expires_at`): it is cancelled, `confirmation_url` becomes null and
+`checkout()` answers 409 `confirmation_expired`. Follow the order through its webhooks:
+`order.created`, then `order.completed` once paid (`order.payment_failed` for a declined charge)
+or `order.cancelled` when the user declines or it expires. `return_url` and `metadata` work for
+every order, also with the user's token (`$user->orders()->create([...])`).
+
+### Changing running subscriptions (trusted apps)
+
+`update()` changes a subscription before its checkout (afterwards only the description).
+`change()` changes price, unit, name, description or discount of a running subscription, like a
+plan change (send only what changes):
+
+```php
+use Anikeen\Id\Resources\AppSubscription;
+
+// upgrade now, prorated: the unused rest of the period is credited, the new price charged for it
+$subscription->change(['apply' => AppSubscription::APPLY_NOW, 'price' => '0.0274', 'name' => 'Cloud Server M']);
+
+// downgrade from the next period on
+$subscription->change(['apply' => AppSubscription::APPLY_PERIOD_END, 'price' => '4.99']);
+$subscription->scheduled_change;       // {applies_at, name, description, unit, price, discount, created_at}
+$subscription->cancelScheduledChange(); // keep the current values after all
+```
+
+- `now` credits the unused part of the current period at the rate it was billed at and charges
+  the rest at the new price, both on the user's open bill. A new `unit` starts a new, fully billed
+  period now. A downgrade whose credit would exceed the open bill is refused with 409
+  `credit_exceeds_bill`: schedule it for the period end instead. 409 `proration_not_possible` when
+  the current period wasn't billed to the subscription (e.g. a takeover); `period_end` works.
+- `period_end` changes nothing now; the next period is billed at the new values. A new
+  `period_end` change replaces the scheduled one, `now` drops it.
+- During a free trial nothing was billed: both just change what the trial ends in.
+- `discount` replaces the discount from the next billed period on, `null` ends it. When the unit
+  changes, a discount that counts in periods or an `amount_off` has to be sent again (422).
+- Subscriptions with a monthly cap change only with `period_end`.
+- Only running subscriptions can change: 409 `not_changeable` for drafts (use `update()`), paused,
+  cancelling, expired and cancelled ones.
+
+When a change takes effect (right away or at the period end), Anikeen ID sends
+`subscription.updated` (`EventType::SUBSCRIPTION_UPDATED`) with the old values of the changed
+fields in `$event['data']['previous_attributes']`. Telling the user about a price increase (and
+getting consent where needed) is up to your app.
+
 ### App orders (trusted apps, no user token)
 
 Orders that bill the app's subscriptions, read with the app's token (scope `orders:client`):
@@ -538,6 +802,188 @@ Each order has `status` (`processing` = current month, still collecting; `pendin
 paid; `completed`; `cancelled`), the totals, `payment_attempts`, `next_payment_attempt_at` (null =
 no more automatic retries) and `last_payment_error`.
 
+Collective (monthly) orders are kept **per app**: your subscriptions are never billed on the same
+order as another app's, even if both use the same `group` (or none); clients delegated to your app
+bill on your app's orders. `$order->oauth_client_id` is the app that bills the order.
+
+Orders also list their lines and their invoice, e.g. to show a team's invoices or to attribute
+amounts (commissions) per subscription:
+
+```php
+$order = app(AnikeenId::class)->appOrders()->find($orderId);
+
+foreach ($order->items as $item) {
+    $item->subscription_id;                     // null for lines that bill no subscription
+    $item->period_start; $item->period_end;     // ISO 8601, the end is exclusive; null without a period
+    $item->net_amount;                          // units × price, rounded to cents
+    $item->discount;                            // {label, percent_off, amount_off} on a discount line, else null
+}
+
+$order->invoice;                                // null until paid, then {id, number, status, …, pdf_url}
+$pdf = app(AnikeenId::class)->appOrders()->invoicePdf($orderId); // the invoice PDF (binary)
+```
+
+The net amount actually billed for a subscription is the sum of `net_amount` of its lines
+(discount lines are negative). `invoicePdf()` throws `ApiException` with 404 `invoice_not_found`
+before the order is paid and 409 `invoice_not_ready` while the PDF is still being rendered
+(usually seconds after the payment; try again later). Legacy orders from before collective orders
+were kept per app (`oauth_client_id` null) can also bill other apps' subscriptions: there `items`
+lists only your lines (the totals are the whole order's), `invoice->pdf_url` is null and
+`invoicePdf()` throws `ApiException` with 403 `invoice_includes_other_apps`.
+
+### Billing portal links (trusted apps)
+
+A "Manage billing" button for a user whose token your app doesn't have (e.g. the owner of a team
+your app bills): create a link to the user's billing pages on Anikeen ID with the app's token
+(scope `subscriptions:client` or `orders:client`). Like Stripe's customer portal, it works
+**without a login**:
+
+```php
+Route::post('teams/{team}/billing', function (Team $team) {
+    return redirect()->away($team->owner->appBillingPortalUrl([
+        'return_url' => route('teams.show', $team), // "Back to <app>"; same origin as one of your redirect URIs
+        'group' => $team->id,                       // only this group's subscriptions, orders and invoices
+        'flow' => 'invoices',                       // overview (default), payment_method, payment_method_update,
+                                                    // invoices, subscriptions or orders
+    ]));
+});
+
+app(AnikeenId::class)->createBillingPortalLinkForUser($userId, ['flow' => 'payment_method_update']);
+// {object: "billing_portal_link", url, user_id, flow, group, return_url, expires_at}
+```
+
+The link is **single use** and valid for about 15 minutes: create it when the user clicks and
+redirect right away; don't store, mail or reuse it (a second request with the same link, e.g. a
+reload, gets a 403). Opening it starts a portal session for that user that needs no login and
+signs nobody in: only the billing pages of the `flow`, only what bills your app's subscriptions
+(of the `group`), with "Back to *app*". The user's account settings, other apps and OAuth consent
+stay behind the normal login; signed in as another account, the portal still shows only the
+link's user. The session ends after an hour without activity or on "Back to *app*".
+`payment_method_update` leads straight to replacing the payment method (e.g. after a failed
+payment) and back to `return_url`. For the signed-in user with their own token,
+`$user->billingPortalUrl()` stays available.
+
+### Charges and billing limit (trusted apps)
+
+Trusted apps can book single items onto a user's **open monthly bill** of the app, e.g. each item
+a shipping app sends: one line per charge, no subscription, charged with the bill on the 1st like
+every other line (invoice and VAT by Anikeen ID). Anikeen has to enable charging for your app and
+sets a maximum per charge; the user must be connected to your app (they authorised it, or your app
+bills them through subscriptions or orders).
+
+```php
+$anikeen = app(AnikeenId::class);
+
+$charge = $anikeen->createChargeForUser($user->anikeen_id, [
+    'idempotency_key' => "shipment-{$shipment->id}", // per app and user: a retry returns the same charge
+    'name' => 'Signed card',                         // the line on the bill
+    'type' => 'physical',                            // digital (default), physical, physical-reduced
+    'quantity' => 2,
+    'unit_price' => '4.00',                          // net per piece, up to 6 decimals
+    'reference' => "order-{$shipment->order_id}",    // your own id; not on the bill
+    // 'group' => $team->id,                         // only a group your app already bills the user in
+    // 'occurred_at' => '2026-11-05T14:00:00Z',      // the service date, at most 31 days ago
+]);
+
+$charge->id();          // keep it to void the charge later
+$charge->grossAmount(); // "9.52": what it added to the bill
+$charge->orderId();     // the monthly bill it is on
+$charge->status();      // open, billed (the bill was closed) or voided
+
+$anikeen->findChargeForUser($user->anikeen_id, $chargeId);
+$anikeen->voidChargeForUser($user->anikeen_id, $chargeId, 'Parcel lost'); // while the bill is open
+```
+
+- **Idempotency:** retrying with the same key and the same fields returns the existing charge
+  (200 instead of 201), also after the limit was reached; the same key with other fields is 409
+  `idempotency_key_conflict` (`charge_id` in `body()`). Use one key per item you charge for.
+- **Voiding** removes the line while the bill is open (an already voided charge is returned as
+  it is). Once the bill was closed: 409 `charge_already_billed`; only a refund of the order by
+  Anikeen credits it.
+- **`group`** is null or a group your app already bills the user in (a running subscription or an
+  open monthly bill of your app); others are refused with 409 `group_not_allowed`.
+- `reference` and `metadata` (up to 20 string values) are your data about the user, kept with the
+  charge and not shown on the bill: put nothing sensitive there.
+
+**Billing limit.** A user can set one monthly limit (gross) for their whole open monthly bill
+across all Anikeen services. A charge that would take the bill above it is refused with 409
+`billing_limit_reached`; exactly reaching the limit is allowed, `0.00` refuses every charge.
+Subscription renewals and usage are still billed, so the bill can end above the limit. Read the
+limit to stop offering paid actions early (advisory only, it reserves nothing):
+
+```php
+$limit = $anikeen->billingLimitForUser($user->anikeen_id);
+
+$limit->hasLimit();     // false: no limit, every charge fits
+$limit->isReached();    // used >= limit: start no new paid service
+$limit->remaining();    // "17.60" gross room left, null without a limit
+$limit->remainingNet(); // "14.78" at the user's VAT rate, a hint
+$limit->allows('9.52'); // would this charge fit right now (advisory)
+$limit->resetsAt();     // when this month's bills are closed
+$limit->version();      // only goes up
+$limit->used();         // the user's open bills across all Anikeen services, null without a limit
+$limit->usedByApp();    // your app's share; used − usedByApp = "your other Anikeen services"
+```
+
+`used` (the user's open bills across all Anikeen services) is visible to apps **only while the
+user has set a limit**; without one `limit`, `used`, `remaining` and `remaining_net` are null.
+`usedByApp()` (your app's own open bills) is always there. The user sees their own limit in
+`$user->billingOverview()->billing_limit` (with `used`, without `used_by_app`; null while they
+can't set one). Apps that may charge can read the limit; others need Anikeen to allow it (403
+`billing_limit_not_enabled`).
+
+Handling a refused charge:
+
+```php
+use Anikeen\Id\Exceptions\ApiException;
+
+try {
+    $charge = $anikeen->createChargeForUser($user->anikeen_id, $attributes);
+} catch (ApiException $e) {
+    if ($e->isBillingLimitReached()) {
+        $e->body()->remaining;  // room left before this charge, e.g. "2.60"
+        $e->body()->required;   // the refused charge, gross
+        $e->body()->resets_at;  // when the limit has room again at the latest
+        return $shipment->holdForBillingLimit();
+    }
+
+    match ($e->error) {
+        'charge_exceeds_maximum' => report($e),   // above your app's maximum ($e->body()->max_charge_net)
+        'group_not_allowed' => report($e),
+        'billing_address_missing' => $shipment->askForBillingAddress(),
+        default => throw $e,
+    };
+}
+```
+
+**Webhooks.** `billing_limit.reached` and `billing_limit.available` are sent when the limit is
+reached or has room again (a raised or removed limit, a void, the monthly reset). They are
+**opt-in** (select them for your endpoint; `*` doesn't include them) and go only to apps that may
+read the limit of a user connected to them. `data.object` is the billing limit as your app reads
+it, `data.reason` says why (`booking`, `limit_changed`, `limit_removed`, `voided`,
+`period_reset`, `order_changed`). Keep the highest `version` per user and ignore events with a
+lower or equal one, so a late delivery can't undo a newer state. In the `match` of the
+[webhook route](#webhooks):
+
+```php
+EventType::BILLING_LIMIT_REACHED, EventType::BILLING_LIMIT_AVAILABLE => Customer::syncBillingLimit(
+    $object['user_id'], reached: $event['type'] === EventType::BILLING_LIMIT_REACHED, version: $object['version'],
+),
+```
+
+The limit is checked live when a charge is booked, so a late or missed webhook never lets a
+charge through; poll `billingLimitForUser()` if you need the current state.
+
+#### Error codes
+
+| Status | `error` |
+|--------|---------|
+| 403 | `client_not_allowed` (not a trusted app with its own token), `charges_not_enabled` (charging is not enabled for your app; also for reads and voids), `billing_limit_not_enabled` (limit read only) |
+| 404 | `user_not_found` (unknown, deleted or not connected to your app), `charge_not_found` |
+| 409 | `billing_limit_reached` (`isBillingLimitReached()`), `charge_exceeds_maximum` (+ `max_charge_net`), `group_not_allowed`, `idempotency_key_conflict` (+ `charge_id`), `billing_address_missing`, `charge_already_billed` (+ `charge_id`) |
+| 422 | validation (`errors`), no `error` code |
+| 429 | `too_many_requests` (`isTemporary()`) |
+
 ### Checkout sessions (the user confirms several subscriptions at once)
 
 Instead of checking subscriptions out itself, an app can let the user confirm them on Anikeen ID,
@@ -595,6 +1041,179 @@ While a session is open, its subscriptions can't be checked out or repriced by t
 `subscription.activated` / `subscription.cancelled` are still sent per subscription, before the
 `checkout.*` event of the session.
 
+### User accounts (trusted apps, no user token)
+
+Trusted apps can look up and create Anikeen ID accounts with the app's own token. Email addresses
+are matched regardless of case.
+
+```php
+$anikeenId = app(AnikeenId::class);
+
+$account = $anikeenId->findUserByEmail('erika@example.com'); // null if no account uses it
+$account?->data->id;                   // also name, email, email_verified, has_billing_address
+
+$result = $anikeenId->createUser([     // finds the account of the email address or creates it
+    'name' => 'Erika Mustermann',
+    'email' => 'erika@example.com',
+    'send_invitation' => true,         // a new account gets a mail with a link to set a password
+]);
+$result->data->created;                // false: the account already existed (and is unchanged)
+$result->data->invitation_sent;        // only for an account created by this call without a password
+```
+
+`findUserByEmail()` changes nothing. It throws `ApiException` when the request fails for any reason
+other than an unknown address.
+
+
+## Preferences
+
+Anikeen ID keeps small per-user settings as JSON values under a *namespace* and a *key*, so they
+follow the user across devices and apps:
+
+- **`global`** is shared by all apps. Only registered keys and values are accepted: today
+  `SharedPreference::APPEARANCE` with `Appearance::SYSTEM`, `LIGHT` or `DARK`.
+- **App namespaces** (e.g. `acme`) hold one app's own data: onboarding state, a default workspace,
+  the user's customer ID at a payment provider. Use another namespace on staging (e.g.
+  `acme-staging`), so test data never mixes with production.
+
+**Registration.** Access never comes from scopes alone: any client can request any scope. Ask
+Anikeen to register your OAuth client(s) (the app has to be [trusted](#trusted-apps)) for
+
+- the namespaces your app owns (read, write and the lookup),
+- read access to another app's namespace,
+- `global` with the app's token (users always read and write their own `global` with their token),
+- keys whose values are unique (see the lookup below).
+
+Without it, app requests fail with 403 `client_not_trusted` or 404 `namespace_not_found`.
+
+**Scopes.** User tokens need `Scope::PREFERENCES` (`preferences`, read and write) or
+`Scope::PREFERENCES_READ` (`preferences:read`); app tokens `Scope::PREFERENCES_CLIENT`
+(`preferences:client`).
+
+**Limits.** A value is at most 2048 bytes of JSON and 4 levels deep; at most 50 keys per user and
+namespace (updating a key always works); keys match `^[a-z][a-z0-9_]{0,63}$`. Per minute: 60
+requests per user and app with user tokens, 600 per app with the app token and 120 lookups per
+app (429 `rate_limited` with `Retry-After`).
+
+**Not a secrets store.** Values are stored as plain JSON and shown to Anikeen's support and to the
+user on a request for their data. Store IDs and settings, never passwords, API keys or tokens: keys
+that look like credentials (`secret`, `token`, `password`, `api_key`, …) are rejected with 422
+`forbidden_key`.
+
+### The user's shared preferences (user token)
+
+```php
+use Anikeen\Id\Enums\Appearance;
+use Anikeen\Id\Enums\SharedPreference;
+
+$user->globalPreference(SharedPreference::APPEARANCE, Appearance::SYSTEM); // the default when not set
+$user->globalPreferences()->values();     // ['appearance' => 'dark']
+
+$preference = $user->setGlobalPreference(SharedPreference::APPEARANCE, Appearance::DARK);
+$preference->version;                     // e.g. 1042
+
+$user->deleteGlobalPreference(SharedPreference::APPEARANCE);
+```
+
+User tokens reach `global` only; an app namespace answers 404 `namespace_not_found`, whatever the
+token's scopes. The app's own token (client credentials) has no user and gets 401 on these routes.
+
+### Preferences of any user (trusted apps)
+
+With the app's own token, by the user's Anikeen ID:
+
+```php
+$anikeenId = app(AnikeenId::class);
+
+$preferences = $anikeenId->preferencesByUserId($userId, 'acme'); // sorted by key, no pagination
+$preferences->get('onboarding', []);     // the value or a default; also has(), find(), values()
+
+$preference = $anikeenId->preferenceByUserId($userId, 'acme', 'onboarding'); // 404 preference_not_found if not set
+$preference->value;                      // JSON objects as stdClass, so {} stays {}
+$preference->version;
+$preference->updated_by;                 // {type: "user"|"app", client_id}
+
+$anikeenId->setPreferenceByUserId($userId, 'acme', 'onboarding', ['step' => 3]);
+$anikeenId->deletePreferenceByUserId($userId, 'acme', 'onboarding');
+```
+
+A value is any JSON value; pass `(object) []` for an empty object (`[]` is an empty list).
+`setPreferenceByUserId()` returns the stored preference; `wasCreated()` tells whether the write
+created the key. A deleted user's preferences are gone: every call answers 404 `user_not_found`.
+
+### Conditional writes and retries
+
+Writes are *last write wins* by default. Every write gives the preference a new `version`.
+Versions are opaque: they only go up (also when a key is deleted and set again) and increase per
+user, not by one per key. Pass the version you read to write only if nobody changed it in between
+(`If-Match`), or `createOnly` to write only if the key isn't set yet (`If-None-Match: *`):
+
+```php
+use Anikeen\Id\Exceptions\PreconditionFailedException;
+
+$preference = $anikeenId->preferenceByUserId($userId, 'acme', 'layout');
+
+try {
+    $anikeenId->setPreferenceByUserId($userId, 'acme', 'layout', $merged, ifVersion: $preference->version);
+} catch (PreconditionFailedException $e) {
+    $e->error;            // "preference_version_mismatch" (or "preference_exists" for createOnly)
+    $e->currentVersion(); // the version stored now, null when the key isn't set: reload, merge, retry
+}
+
+$anikeenId->setPreferenceByUserId($userId, 'acme', 'welcome_sent_at', now()->toIso8601String(), createOnly: true);
+```
+
+`deletePreferenceByUserId()`, `setGlobalPreference()` and `deleteGlobalPreference()` take
+`ifVersion` too. Writing the value that is already stored is a no-op that succeeds (no new version),
+even when the precondition would fail, so retrying a write after a timeout is safe.
+
+### Unique keys and the lookup
+
+Anikeen can declare keys of your namespace unique, e.g. `customer_id`. Their values are strings of
+1 to 255 characters without surrounding whitespace, held by at most one user: setting another
+user's value fails with 409 `preference_value_taken`. Your app can then find the user by value, e.g.
+in a payment provider's webhook:
+
+```php
+$userId = $anikeenId->findUserIdByPreference('acme', 'customer_id', 'cus_123'); // null if nobody holds it
+```
+
+The value is sent in the body, never in the URL. `findUserIdByPreference()` returns `null` only for
+404 `preference_not_found` (also when the user was deleted); everything else throws, e.g. 422
+`key_not_unique` for a key that isn't declared unique.
+
+### Error codes
+
+Failures throw `ApiException` (412 `PreconditionFailedException`) with these `error` codes:
+
+| Status | `error` |
+|--------|---------|
+| 401 | `unauthenticated` (no or an invalid token; an app token on the user routes) |
+| 403 | `missing_scope`, `app_token_required` (a user token on the app routes), `client_not_trusted`, `namespace_read_only`, `lookup_not_allowed` |
+| 404 | `namespace_not_found` (unknown or not accessible), `user_not_found` (also deleted users), `preference_not_found`, `not_found` |
+| 405 | `method_not_allowed` |
+| 409 | `preference_value_taken` |
+| 412 | `preference_version_mismatch`, `preference_exists` |
+| 422 | `invalid_key`, `forbidden_key`, `unknown_shared_key`, `value_required`, `value_too_large`, `value_too_deep`, `invalid_shared_value`, `invalid_unique_value`, `key_not_unique`, `preference_limit_exceeded` |
+| 429 | `rate_limited` |
+
+A `null` value is rejected with 422 `value_required`: delete the key instead.
+
+### Caching
+
+Anikeen ID is the source of truth. `globalPreferences()` and `globalPreference()` cache the list
+on the model instance (one request per instance); `setGlobalPreference()` and
+`deleteGlobalPreference()` clear it. For a copy that outlives the request, keep a read cache: fill
+it at sign-in, write to Anikeen ID first and update the copy from the response, and let it expire
+after about an hour, since other apps and the user can change shared preferences too:
+
+```php
+$appearance = Cache::remember("appearance:{$user->id}", now()->addHour(),
+    fn () => $user->globalPreference(SharedPreference::APPEARANCE, Appearance::SYSTEM));
+
+$user->setGlobalPreference(SharedPreference::APPEARANCE, $request->appearance);
+Cache::put("appearance:{$user->id}", $request->appearance, now()->addHour());
+```
 
 ## API authentication
 

composer.json

@@ -15,15 +15,15 @@
   "require": {
     "php": "^8.2",
     "ext-json": "*",
-    "illuminate/support": "^11.0|^12.0|^13.0",
+    "illuminate/support": "^12.69|^13.0",
-    "illuminate/console": "^11.0|^12.0|^13.0",
+    "illuminate/console": "^12.69|^13.0",
     "guzzlehttp/guzzle": "^7.8",
     "socialiteproviders/manager": "^4.6",
-    "firebase/php-jwt": "^6.10|^7.0"
+    "firebase/php-jwt": "^7.0"
   },
   "require-dev": {
-    "laravel/framework": "^11.0|^12.0|^13.0",
+    "laravel/framework": "^12.69|^13.0",
-    "orchestra/testbench": "^9.0|^10.0|^11.0",
+    "orchestra/testbench": "^10.0|^11.0",
     "phpunit/phpunit": "^11.0|^12.0"
   },
   "autoload": {

src/Id/AnikeenId.php

@@ -2,6 +2,7 @@
 
 namespace Anikeen\Id;
 
+use Anikeen\Id\Concerns\ManagesPreferences;
 use Anikeen\Id\Concerns\ManagesPricing;
 use Anikeen\Id\Concerns\ManagesProducts;
 use Anikeen\Id\Concerns\ManagesShippingLabels;
@@ -23,6 +24,7 @@ use Illuminate\Contracts\Auth\Authenticatable;
 class AnikeenId
 {
     use OauthTrait;
+    use ManagesPreferences;
     use ManagesPricing;
     use ManagesProducts;
     use ManagesShippingLabels;
@@ -369,10 +371,12 @@ class AnikeenId
     /**
      * Build query & execute.
      *
+     * @param array<string, string> $headers Extra request headers, e.g. `If-Match` for conditional
+     *     writes; they are sent in addition to (and may not replace) Client-ID, Accept and Authorization.
      * @throws GuzzleException
      * @throws RequestRequiresClientIdException
      */
-    public function request(string $method, string $path, null|array $payload = null, array $parameters = [], ?Paginator $paginator = null, bool $useClientSecret = false): Result
+    public function request(string $method, string $path, null|array $payload = null, array $parameters = [], ?Paginator $paginator = null, bool $useClientSecret = false, array $headers = []): Result
     {
         if ($paginator !== null) {
             $parameters[$paginator->action] = $paginator->cursor();
@@ -380,7 +384,7 @@ class AnikeenId
 
         try {
             $response = $this->client->request($method, $path, [
-                'headers' => $this->buildHeaders((bool)$payload, $useClientSecret),
+                'headers' => $this->buildHeaders((bool)$payload, $useClientSecret) + $headers,
                 'query' => Query::build($parameters),
                 'json' => $payload ?: null,
             ]);
@@ -419,35 +423,35 @@ class AnikeenId
      * @throws GuzzleException
      * @throws RequestRequiresClientIdException
      */
-    public function get(string $path, array $parameters = [], ?Paginator $paginator = null): Result
+    public function get(string $path, array $parameters = [], ?Paginator $paginator = null, array $headers = []): Result
     {
-        return $this->request('GET', $path, null, $parameters, $paginator);
+        return $this->request('GET', $path, null, $parameters, $paginator, false, $headers);
     }
 
     /**
      * @throws GuzzleException
      * @throws RequestRequiresClientIdException
      */
-    public function post(string $path, array $payload = [], array $parameters = [], ?Paginator $paginator = null): Result
+    public function post(string $path, array $payload = [], array $parameters = [], ?Paginator $paginator = null, array $headers = []): Result
     {
-        return $this->request('POST', $path, $payload, $parameters, $paginator);
+        return $this->request('POST', $path, $payload, $parameters, $paginator, false, $headers);
     }
 
     /**
      * @throws GuzzleException
      * @throws RequestRequiresClientIdException
      */
-    public function put(string $path, array $payload = [], array $parameters = [], ?Paginator $paginator = null): Result
+    public function put(string $path, array $payload = [], array $parameters = [], ?Paginator $paginator = null, array $headers = []): Result
     {
-        return $this->request('PUT', $path, $payload, $parameters, $paginator);
+        return $this->request('PUT', $path, $payload, $parameters, $paginator, false, $headers);
     }
 
     /**
      * @throws GuzzleException
      * @throws RequestRequiresClientIdException
      */
-    public function delete(string $path, array $payload = [], array $parameters = [], ?Paginator $paginator = null): Result
+    public function delete(string $path, array $payload = [], array $parameters = [], ?Paginator $paginator = null, array $headers = []): Result
     {
-        return $this->request('DELETE', $path, $payload, $parameters, $paginator);
+        return $this->request('DELETE', $path, $payload, $parameters, $paginator, false, $headers);
     }
 }

src/Id/Billable.php

@@ -9,6 +9,7 @@ use Anikeen\Id\Concerns\ManagesInvoices;
 use Anikeen\Id\Concerns\ManagesOrders;
 use Anikeen\Id\Concerns\ManagesPaymentMethods;
 use Anikeen\Id\Concerns\ManagesProfile;
+use Anikeen\Id\Concerns\ManagesUserPreferences;
 use Anikeen\Id\Concerns\ManagesSubscriptions;
 use Anikeen\Id\Concerns\ManagesTaxation;
 use Anikeen\Id\Concerns\ManagesTransactions;
@@ -27,6 +28,7 @@ trait Billable
     use ManagesSubscriptions;
     use ManagesTaxation;
     use ManagesTransactions;
+    use ManagesUserPreferences;
     use ManagesUserSshKeys;
 
     /*
@@ -40,6 +42,8 @@ trait Billable
     protected mixed $invoicesCache = null;
     protected mixed $ordersCache = null;
     protected mixed $paymentMethodsCache = null;
+    /** @var array<string, \Anikeen\Id\Resources\Preferences> by namespace */
+    protected array $preferencesCache = [];
     protected mixed $subscriptionsCache = null;
     protected mixed $transactionsCache = null;
     protected mixed $userDataCache = null;

src/Id/Concerns/HasSubscriptionStatus.php

@@ -48,6 +48,14 @@ trait HasSubscriptionStatus
         return in_array($this->status(), [SubscriptionStatus::TRIAL, SubscriptionStatus::ACTIVE, SubscriptionStatus::PAUSED, SubscriptionStatus::CANCELLING], true);
     }
 
+    /**
+     * In its free trial: running, nothing billed until trial_ends_at.
+     */
+    public function isTrial(): bool
+    {
+        return $this->status() === SubscriptionStatus::TRIAL;
+    }
+
     /**
      * Paused: runs until the paid period ends, then expires (resume() to continue).
      */

src/Id/Concerns/ManagesBalance.php

@@ -31,7 +31,13 @@ trait ManagesBalance
 
     /**
      * Billing overview of the current user: current_balance, current_charges, vat_rate,
-     * has_billing_address, has_default_payment_method, open_orders.
+     * has_billing_address, has_default_payment_method, open_orders and billing_limit.
+     *
+     * billing_limit is the user's monthly billing limit {object: "billing_limit", user_id,
+     * currency, basis, limit, used, remaining, remaining_net, vat_rate, reached, resets_at,
+     * version} (`limit`, `remaining` and `remaining_net` null without a limit; wrap it in
+     * `new \Anikeen\Id\Resources\BillingLimit(…)` for its helpers), or null while the user has no
+     * limit and can't set one yet. Older Anikeen ID releases don't send the key.
      *
      * @throws Throwable
      */

src/Id/Concerns/ManagesPreferences.php

@@ -0,0 +1,107 @@
+<?php
+
+namespace Anikeen\Id\Concerns;
+
+use Anikeen\Id\Exceptions\ApiException;
+use Anikeen\Id\Exceptions\PreconditionFailedException;
+use Anikeen\Id\Resources\Preference;
+use Anikeen\Id\Resources\Preferences;
+use Anikeen\Id\Support\AppRequest;
+use Anikeen\Id\Support\PreferenceRequest;
+
+/**
+ * Preferences of any user, with the app's own token (client credentials, scope
+ * `preferences:client`). Anikeen has to register the app for each namespace it uses: its own
+ * namespaces (read, write, lookup), read access to another app's namespace, or access to `global`.
+ * Without it every call fails with 403 "client_not_trusted" or 404 "namespace_not_found".
+ */
+trait ManagesPreferences
+{
+    /**
+     * All preferences of a user in a namespace, sorted by key.
+     *
+     * @throws ApiException 404 "namespace_not_found", "user_not_found" (also deleted users), …
+     */
+    public function preferencesByUserId(string $userId, string $namespace): Preferences
+    {
+        return Preferences::builder(fn () => AppRequest::send('GET', $this->userPreferencePath($userId, $namespace)));
+    }
+
+    /**
+     * One preference of a user.
+     *
+     * @throws ApiException 404 "preference_not_found" when the key isn't set, "user_not_found", …
+     */
+    public function preferenceByUserId(string $userId, string $namespace, string $key): Preference
+    {
+        return new Preference(fn () => AppRequest::send('GET', $this->userPreferencePath($userId, $namespace, $key)));
+    }
+
+    /**
+     * Set a preference of a user. The value is any JSON value (pass `(object) []` for `{}`), at
+     * most 2048 bytes and 4 levels deep. Writing the value already stored changes nothing and
+     * succeeds, also when a precondition would fail, so a retried write is safe.
+     *
+     * @param int|null $ifVersion only if the stored version is this one (`If-Match`)
+     * @param bool $createOnly only if the key isn't set yet (`If-None-Match: *`); not with $ifVersion
+     * @throws PreconditionFailedException 412 "preference_version_mismatch" / "preference_exists",
+     *     with currentVersion()
+     * @throws ApiException 403 "namespace_read_only", 409 "preference_value_taken" (a unique key),
+     *     422 "invalid_key", "forbidden_key", "value_too_large", "preference_limit_exceeded", …
+     */
+    public function setPreferenceByUserId(string $userId, string $namespace, string $key, mixed $value, ?int $ifVersion = null, bool $createOnly = false): Preference
+    {
+        $headers = PreferenceRequest::conditions($ifVersion, $createOnly);
+
+        return new Preference(fn () => AppRequest::send('PUT', $this->userPreferencePath($userId, $namespace, $key), ['value' => $value], [], $headers));
+    }
+
+    /**
+     * Delete a preference of a user.
+     *
+     * @param int|null $ifVersion only if the stored version is this one (`If-Match`)
+     * @throws PreconditionFailedException 412 "preference_version_mismatch", with currentVersion()
+     * @throws ApiException 404 "preference_not_found" when the key isn't set, …
+     */
+    public function deletePreferenceByUserId(string $userId, string $namespace, string $key, ?int $ifVersion = null): void
+    {
+        AppRequest::send('DELETE', $this->userPreferencePath($userId, $namespace, $key), null, [], PreferenceRequest::conditions($ifVersion));
+    }
+
+    /**
+     * The ID of the user holding a value of a unique key in one of the app's own namespaces, e.g.
+     * the user of a payment provider's customer ID. The value is sent in the body, never in the URL.
+     *
+     * @return string|null null when no (not deleted) user holds the value
+     * @throws ApiException 422 "key_not_unique", "invalid_unique_value", 403 "lookup_not_allowed", …
+     */
+    public function findUserIdByPreference(string $namespace, string $key, string $value): ?string
+    {
+        try {
+            $result = AppRequest::send('POST', PreferenceRequest::path('v1/client/preferences', $namespace, 'lookup'), [
+                'key' => $key,
+                'value' => $value,
+            ]);
+        } catch (ApiException $e) {
+            // only Anikeen ID's own answer means "nobody holds it", not e.g. an unknown namespace
+            if ($e->isNotFound() && $e->error === 'preference_not_found') {
+                return null;
+            }
+
+            throw $e;
+        }
+
+        return $result->data->user_id;
+    }
+
+    private function userPreferencePath(string $userId, string $namespace, ?string $key = null): string
+    {
+        $segments = [$userId, 'preferences', $namespace];
+
+        if ($key !== null) {
+            $segments[] = $key;
+        }
+
+        return PreferenceRequest::path('v1/client/users', ...$segments);
+    }
+}

src/Id/Concerns/ManagesSubscriptions.php

@@ -2,6 +2,8 @@
 
 namespace Anikeen\Id\Concerns;
 
+use Anikeen\Id\AnikeenId;
+use Anikeen\Id\Exceptions\ApiException;
 use Anikeen\Id\Resources\AppCheckoutSessions;
 use Anikeen\Id\Resources\AppOrders;
 use Anikeen\Id\Resources\AppSubscriptions;
@@ -65,4 +67,20 @@ trait ManagesSubscriptions
     {
         return new AppOrders($this);
     }
+
+    /**
+     * A link to the user's billing pages on Anikeen ID that needs no login, created with the app's
+     * own token (trusted apps only, scope subscriptions:client or orders:client), e.g. for a
+     * "Manage billing" button; see AnikeenId::createBillingPortalLinkForUser() for the attributes
+     * (return_url, group, flow). Single use and valid for about 15 minutes: create it when the
+     * user clicks and redirect right away.
+     *
+     * @param array{return_url?: null|string, group?: null|string, flow?: null|string} $attributes
+     *
+     * @throws ApiException
+     */
+    public function appBillingPortalUrl(array $attributes = []): string
+    {
+        return app(AnikeenId::class)->createBillingPortalLinkForUser($this->appSubscriptions()->userId(), $attributes)->url;
+    }
 }

src/Id/Concerns/ManagesUserBilling.php

@@ -2,9 +2,13 @@
 
 namespace Anikeen\Id\Concerns;
 
+use Anikeen\Id\Exceptions\ApiException;
+use Anikeen\Id\Resources\AppCharge;
 use Anikeen\Id\Resources\AppCheckoutSessions;
 use Anikeen\Id\Resources\AppOrders;
+use Anikeen\Id\Resources\BillingLimit;
 use Anikeen\Id\Result;
+use Anikeen\Id\Support\AppRequest;
 use Throwable;
 
 /**
@@ -29,11 +33,48 @@ trait ManagesUserBilling
         return new AppCheckoutSessions();
     }
 
+    /**
+     * A link to a user's billing pages on Anikeen ID that needs no login, like Stripe's customer
+     * portal, e.g. for a "Manage billing" button of an app that bills another user's account (a
+     * team owner) without that user's token (trusted apps, scope subscriptions:client or
+     * orders:client). The link is single use and valid for about 15 minutes: create it when the
+     * user clicks and redirect right away, don't store it. It opens a portal session for that user
+     * only (no login, nobody signed in) with only the flow's billing pages and only what bills the
+     * app's subscriptions (of the group), leading back to return_url; it ends after an hour
+     * without activity.
+     *
+     * @param string $userId The user's Anikeen ID.
+     * @param array{
+     *     return_url?: null|string,
+     *     group?: null|string,
+     *     flow?: null|string
+     * } $attributes return_url: "Back to the app" (same origin as one of the app's redirect URIs,
+     *               422 otherwise).
+     *               group: only this group's subscriptions and the orders, invoices and
+     *               transactions billing them.
+     *               flow: overview (default), payment_method, payment_method_update (straight to
+     *               replacing the payment method, e.g. after a failed payment), invoices,
+     *               subscriptions or orders.
+     * @return object {object: "billing_portal_link", url, user_id, flow, group, return_url, expires_at}
+     *
+     * @throws ApiException 403 untrusted app or missing scope, 404 unknown user, 422 validation
+     */
+    public function createBillingPortalLinkForUser(string $userId, array $attributes = []): object
+    {
+        return AppRequest::send('POST', sprintf('v1/client/users/%s/billing-portal', $userId), $attributes)->data;
+    }
+
     /**
      * Create an order for a user (VAT from the billing address). With `checkout`, it is paid right
      * away: with the given `transaction` (a payment captured elsewhere) or by charging the user's
      * default payment method (402 when declined; the order stays pending and is retried).
      *
+     * With `confirm`, the user confirms and pays it on Anikeen ID instead (e.g. a top-up): the
+     * order stays a draft with `confirmation_url` (send the user there) and is cancelled if not
+     * confirmed within 24 hours (`expires_at`; afterwards checking it out answers 409
+     * "confirmation_expired"). Webhooks: order.created, order.completed once paid, or
+     * order.cancelled when the user declines or it expires.
+     *
      * @param string $userId The user's Anikeen ID.
      * @param array{
      *     group?: string,
@@ -43,11 +84,18 @@ trait ManagesUserBilling
      *     shipping_address?: array,
      *     items: array<array{type: string, name: string, description?: string, image_url?: string, price?: float|string, gross_price?: float|string, unit: string, units: int}>,
      *     checkout?: bool,
+     *     confirm?: bool,
+     *     return_url?: null|string,
+     *     metadata?: null|array,
      *     transaction_id?: string,
      *     transaction?: array,
      *     invoice_date?: string,
      *     currency_iso?: string
-     * } $attributes
+     * } $attributes confirm: needs items, can't be combined with checkout or a transaction.
+     *               return_url: where the user returns after confirming, with `status` and
+     *               `order` (same origin as one of the app's redirect URIs, 422 otherwise).
+     *               metadata: the app's own data (max. 50 keys), returned as is in the API and
+     *               the order webhooks.
      * @throws Throwable
      */
     public function createOrderForUser(string $userId, array $attributes): Result
@@ -77,4 +125,101 @@ trait ManagesUserBilling
     {
         return $this->asApp()->request('POST', 'v1/admin/transactions', [...$attributes, 'user_id' => $userId]);
     }
+
+    /**
+     * Book a charge onto a user's open monthly bill of the app, e.g. a shipped item: one line,
+     * no subscription, charged with the bill on the 1st. Trusted apps that Anikeen allowed to
+     * charge (with a maximum per charge), for users connected to the app (they authorised it or
+     * the app bills them). The user's billing limit is checked when it is booked.
+     *
+     * Retrying with the same idempotency key and the same fields returns the existing charge
+     * (also after the limit was reached); other fields with that key: 409
+     * "idempotency_key_conflict" (`charge_id` in body()).
+     *
+     * @param string $userId The user's Anikeen ID.
+     * @param array{
+     *     idempotency_key: string,
+     *     name: string,
+     *     description?: null|string,
+     *     type?: string,
+     *     quantity: int,
+     *     unit_price: float|int|string,
+     *     currency_iso?: string,
+     *     group?: null|string,
+     *     occurred_at?: string,
+     *     reference?: null|string,
+     *     metadata?: null|array<string, string>,
+     *     image_url?: null|string
+     * } $attributes idempotency_key: unique per app and user, ≤ 255 (e.g. "shipment-123").
+     *               name: the line on the bill, ≤ 255. description: ≤ 255.
+     *               type: digital (default), physical or physical-reduced (the VAT treatment).
+     *               quantity: 1–10000 pieces. unit_price: net per piece, > 0, ≤ 100000, up to 6
+     *               decimals; quantity × unit_price rounded to cents must be at least 0.01.
+     *               currency_iso: EUR only (default).
+     *               group: null, or a group in which the app already bills the user (a running
+     *               subscription or an open monthly bill of the app).
+     *               occurred_at: the service date, not in the future, at most 31 days ago
+     *               (default now).
+     *               reference: the app's own id (≤ 255). metadata: ≤ 20 keys (≤ 40 characters),
+     *               string values ≤ 500. Both are not on the bill; put nothing sensitive there.
+     *               image_url: http(s) URL of an image for the line.
+     *
+     * @throws ApiException 403 "client_not_allowed" (not a trusted app), "charges_not_enabled";
+     *     404 "user_not_found" (unknown, deleted or not connected); 409 "billing_limit_reached"
+     *     (isBillingLimitReached(); body() has limit, used, remaining, remaining_net, required,
+     *     currency, resets_at), "charge_exceeds_maximum" (+ max_charge_net),
+     *     "group_not_allowed", "idempotency_key_conflict" (+ charge_id),
+     *     "billing_address_missing"; 422 validation; 429 "too_many_requests"
+     */
+    public function createChargeForUser(string $userId, array $attributes): AppCharge
+    {
+        return new AppCharge(AppRequest::send('POST', $this->chargesPath($userId), $attributes)->data);
+    }
+
+    /**
+     * A charge of the app (or of a client delegated to the same app) for a user.
+     *
+     * @throws ApiException 403 "client_not_allowed", "charges_not_enabled"; 404 "user_not_found",
+     *     "charge_not_found"; 429 "too_many_requests"
+     */
+    public function findChargeForUser(string $userId, string $chargeId): AppCharge
+    {
+        return new AppCharge(AppRequest::send('GET', $this->chargesPath($userId, $chargeId))->data);
+    }
+
+    /**
+     * Void a charge while its bill is open: the line is removed and the bill's total drops. An
+     * already voided charge is returned as it is. Once the bill is closed only a refund of the
+     * order by Anikeen credits it.
+     *
+     * @param string|null $reason why (≤ 255), stored with the charge
+     * @throws ApiException 409 "charge_already_billed" (+ charge_id); 404 "charge_not_found",
+     *     "user_not_found"; 403 "client_not_allowed", "charges_not_enabled"; 429 "too_many_requests"
+     */
+    public function voidChargeForUser(string $userId, string $chargeId, ?string $reason = null): AppCharge
+    {
+        $payload = $reason === null ? null : ['reason' => $reason];
+
+        return new AppCharge(AppRequest::send('POST', $this->chargesPath($userId, $chargeId) . '/void', $payload)->data);
+    }
+
+    /**
+     * A user's monthly billing limit as the app sees it, e.g. to pause paid features while it is
+     * reached. Advisory only: it reserves nothing; a charge is checked when it is booked. Trusted
+     * apps that may charge or that Anikeen allowed to read limits, for users connected to the app.
+     *
+     * @throws ApiException 403 "client_not_allowed", "billing_limit_not_enabled"; 404
+     *     "user_not_found"; 429 "too_many_requests"
+     */
+    public function billingLimitForUser(string $userId): BillingLimit
+    {
+        return new BillingLimit(AppRequest::send('GET', sprintf('v1/client/users/%s/billing-limit', rawurlencode($userId)))->data);
+    }
+
+    private function chargesPath(string $userId, ?string $chargeId = null): string
+    {
+        $path = sprintf('v1/client/users/%s/charges', rawurlencode($userId));
+
+        return $chargeId === null ? $path : $path . '/' . rawurlencode($chargeId);
+    }
 }

src/Id/Concerns/ManagesUserPreferences.php

@@ -0,0 +1,96 @@
+<?php
+
+namespace Anikeen\Id\Concerns;
+
+use Anikeen\Id\Enums\SharedPreference;
+use Anikeen\Id\Exceptions\ApiException;
+use Anikeen\Id\Exceptions\PreconditionFailedException;
+use Anikeen\Id\Resources\Preference;
+use Anikeen\Id\Resources\Preferences;
+use Anikeen\Id\Support\PreferenceRequest;
+use GuzzleHttp\Exception\GuzzleException;
+
+/**
+ * The user's shared preferences (`global`, e.g. SharedPreference::APPEARANCE), with the user's
+ * token (scope `preferences` or `preferences:read`). User tokens reach `global` only; an app's
+ * own namespace needs the app token (AnikeenId::preferencesByUserId()).
+ */
+trait ManagesUserPreferences
+{
+    /**
+     * The user's shared preferences, sorted by key. Cached on this instance; set and delete clear it.
+     *
+     * @throws ApiException
+     */
+    public function globalPreferences(): Preferences
+    {
+        $namespace = SharedPreference::NAMESPACE;
+
+        if (!isset($this->preferencesCache[$namespace])) {
+            $anikeenId = $this->anikeenId();
+
+            $this->preferencesCache[$namespace] = Preferences::builder(
+                fn () => $anikeenId->get(PreferenceRequest::path('v1/preferences', $namespace))
+            );
+        }
+
+        return $this->preferencesCache[$namespace];
+    }
+
+    /**
+     * The value of a shared preference, or $default when the user hasn't set it.
+     *
+     * @throws ApiException
+     */
+    public function globalPreference(string $key, mixed $default = null): mixed
+    {
+        return $this->globalPreferences()->get($key, $default);
+    }
+
+    /**
+     * Set a shared preference of the user, e.g. setGlobalPreference(SharedPreference::APPEARANCE,
+     * Appearance::DARK). Only registered keys and values are accepted (422 "unknown_shared_key",
+     * "invalid_shared_value").
+     *
+     * @param int|null $ifVersion only if the stored version is this one (`If-Match`)
+     * @throws PreconditionFailedException 412 "preference_version_mismatch", with currentVersion()
+     * @throws ApiException
+     */
+    public function setGlobalPreference(string $key, mixed $value, ?int $ifVersion = null): Preference
+    {
+        $namespace = SharedPreference::NAMESPACE;
+        $headers = PreferenceRequest::conditions($ifVersion);
+        $anikeenId = $this->anikeenId();
+
+        try {
+            return new Preference(fn () => $anikeenId->put(PreferenceRequest::path('v1/preferences', $namespace, $key), ['value' => $value], [], null, $headers));
+        } finally {
+            unset($this->preferencesCache[$namespace]);
+        }
+    }
+
+    /**
+     * Delete a shared preference of the user.
+     *
+     * @param int|null $ifVersion only if the stored version is this one (`If-Match`)
+     * @throws PreconditionFailedException 412 "preference_version_mismatch", with currentVersion()
+     * @throws ApiException 404 "preference_not_found" when the key isn't set, …
+     */
+    public function deleteGlobalPreference(string $key, ?int $ifVersion = null): void
+    {
+        $namespace = SharedPreference::NAMESPACE;
+        $headers = PreferenceRequest::conditions($ifVersion);
+
+        try {
+            $result = $this->anikeenId()->delete(PreferenceRequest::path('v1/preferences', $namespace, $key), [], [], null, $headers);
+        } catch (GuzzleException $e) {
+            throw ApiException::unreachable($e);
+        } finally {
+            unset($this->preferencesCache[$namespace]);
+        }
+
+        if (!$result->success()) {
+            throw ApiException::fromResult($result);
+        }
+    }
+}

src/Id/Concerns/ManagesUsers.php

@@ -5,7 +5,9 @@ namespace Anikeen\Id\Concerns;
 
 use Anikeen\Id\ApiOperations\Get;
 use Anikeen\Id\ApiOperations\Post;
+use Anikeen\Id\Exceptions\ApiException;
 use Anikeen\Id\Result;
+use Anikeen\Id\Support\AppRequest;
 use Throwable;
 
 trait ManagesUsers
@@ -24,20 +26,32 @@ trait ManagesUsers
     }
 
     /**
-     * Creates a new user on behalf of the current user.
+     * Finds the account of an email address or creates it (trusted apps, app token). The email
+     * address is matched regardless of case; a new account stores it in lower case, unverified.
+     * An existing account is returned unchanged (only a missing name is filled in).
      *
      * @param array{
-     *       first_name: null|string,
+     *       name?: null|string,
-     *       last_name: null|string,
+     *       first_name?: null|string,
-     *       username: null|string,
+     *       last_name?: null|string,
+     *       username?: null|string,
      *       email: string,
-     *       password: null|string
+     *       password?: null|string,
+     *       password_confirmation?: null|string,
+     *       send_invitation?: bool
      *   } $attributes The user data
-     *     - first_name:  The first name (optional)
+     *     - name:                  The display name (optional)
-     *     - last_name:   The last name (optional)
+     *     - first_name:            The first name (optional, joined with last_name into name)
-     *     - username:    The username (optional)
+     *     - last_name:             The last name (optional, joined with first_name into name)
-     *     - email:       The email (required)
+     *     - username:              The username (optional)
-     *     - password:    The password (optional, can be reset by the user if not provided)
+     *     - email:                 The email (required)
+     *     - password:              The password (optional, can be reset by the user if not provided)
+     *     - password_confirmation: Defaults to password
+     *     - send_invitation:       Send the user an invitation mail with a link to set a password
+     *                              (optional, only when this call created the account without a
+     *                              password, never for an existing account)
+     * @return Result `data` is the user plus `created` (this call created the account) and
+     *     `invitation_sent` (the invitation mail was sent); 201 when created, 200 when it existed
      * @throws Throwable
      */
     public function createUser(array $attributes): Result
@@ -57,6 +71,30 @@ trait ManagesUsers
         return $this->asApp()->post('v1/admin/users', $attributes);
     }
 
+    /**
+     * Looks up the account of an email address without creating or changing anything (trusted
+     * apps, app token). The email address is matched regardless of case.
+     *
+     * `data` is `object{id: string, name: ?string, email: string, email_verified: bool,
+     * has_billing_address: bool}`.
+     *
+     * @return Result|null null when no account uses the email address
+     * @throws ApiException when the request fails for another reason
+     */
+    public function findUserByEmail(string $email): ?Result
+    {
+        try {
+            return AppRequest::send('POST', 'v1/admin/users/lookup', ['email' => $email]);
+        } catch (ApiException $e) {
+            // only Anikeen ID's own answer means "no account", not e.g. an unknown route
+            if ($e->isNotFound() && $e->error === 'user_not_found') {
+                return null;
+            }
+
+            throw $e;
+        }
+    }
+
     /**
      * Find the user of a social login or create it (trusted apps, app token).
      *

src/Id/Enums/Appearance.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace Anikeen\Id\Enums;
+
+/**
+ * The values of the shared preference SharedPreference::APPEARANCE.
+ */
+class Appearance
+{
+    /** Follow the operating system. */
+    const SYSTEM = 'system';
+    const LIGHT = 'light';
+    const DARK = 'dark';
+
+    /**
+     * @return list<string>
+     */
+    public static function all(): array
+    {
+        return [self::SYSTEM, self::LIGHT, self::DARK];
+    }
+}

src/Id/Enums/CancellationReason.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace Anikeen\Id\Enums;
+
+/**
+ * `cancellation_reason` of a subscription (and `data.reason` of `subscription.cancelled`): why
+ * Anikeen ID's billing ended it. Null when the user, the app or an admin cancelled it.
+ */
+class CancellationReason
+{
+    /** Its free trial (`trial_payment_method` optional) ended without a payment method: cancelled at the trial's end, nothing billed. */
+    const TRIAL_ENDED_WITHOUT_PAYMENT_METHOD = 'trial_ended_without_payment_method';
+}

src/Id/Enums/Scope.php

@@ -33,8 +33,25 @@ class Scope
     const TRANSACTIONS_READ = 'transactions:read';
     const TRANSACTIONS_CLIENT = 'transactions:client';
 
+    // The user's own shared preferences (`global`). PREFERENCES_CLIENT labels an app token for
+    // the preferences of any user; access to a namespace is granted by Anikeen, not by the scope.
+    const PREFERENCES = 'preferences';
+    const PREFERENCES_READ = 'preferences:read';
+    const PREFERENCES_CLIENT = 'preferences:client';
+
     const SSH_KEYS = 'ssh-keys';
     const SSH_KEYS_READ = 'ssh-keys:read';
 
+    // Products of the Anikeen Console (servers, floating IPs, hosting, domains, zones, object storage),
+    // read-only. Changing products needs `user`; there is no full `products` scope.
+    const PRODUCTS_READ = 'products:read';
+
+    // Reseller API of the Anikeen Console. A full scope includes reading; `user` and `*` do not
+    // open these endpoints, a token must carry the reseller scope itself.
+    const RESELLER_CUSTOMERS = 'reseller-customers';
+    const RESELLER_CUSTOMERS_READ = 'reseller-customers:read';
+    const RESELLER_GRANTS = 'reseller-grants';
+    const RESELLER_ORDERS = 'reseller-orders';
+
     const ADMIN = 'admin';
 }

src/Id/Enums/SharedPreference.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Anikeen\Id\Enums;
+
+/**
+ * The keys of the `global` preferences namespace, shared by all apps. Anikeen ID accepts only
+ * these keys there, each with its own values.
+ */
+class SharedPreference
+{
+    /** The namespace of the shared preferences. */
+    const NAMESPACE = 'global';
+
+    /** Light or dark mode: one of the Appearance constants. */
+    const APPEARANCE = 'appearance';
+}

src/Id/Enums/TrialPaymentMethod.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Anikeen\Id\Enums;
+
+/**
+ * `trial_payment_method` of a subscription with a free trial: whether the user needs a payment
+ * method to confirm it. Null on subscriptions without a trial.
+ */
+class TrialPaymentMethod
+{
+    /** A payment method is needed to confirm the trial (the default). */
+    const REQUIRED = 'required';
+
+    /**
+     * The trial can be confirmed without a payment method (if nothing else has to be paid). If the
+     * user still has none when the trial ends, the subscription is cancelled then instead of billed
+     * (`cancellation_reason` CancellationReason::TRIAL_ENDED_WITHOUT_PAYMENT_METHOD).
+     */
+    const OPTIONAL = 'optional';
+}

src/Id/Exceptions/ApiException.php

@@ -3,6 +3,7 @@
 namespace Anikeen\Id\Exceptions;
 
 use Anikeen\Id\Result;
+use Psr\Http\Message\ResponseInterface;
 use Throwable;
 
 /**
@@ -27,10 +28,16 @@ class ApiException extends ResourceException
     public static function fromResult(Result $result): static
     {
         $body = is_object($result->data) ? $result->data : null;
+        $status = $result->response()?->getStatusCode() ?? 0;
+
+        // a failed conditional write; subclasses (CollectionException) keep their own type
+        if ($status === 412 && static::class === self::class) {
+            return PreconditionFailedException::fromResult($result);
+        }
 
         return new static(
             rtrim((string) ($body->message ?? $result->error()), '.'),
-            $result->response()?->getStatusCode() ?? 0,
+            $status,
             $body->error ?? null,
             $result->exception,
         );
@@ -44,6 +51,24 @@ class ApiException extends ResourceException
         return new static(sprintf('Anikeen ID is not reachable: %s', $previous->getMessage()), 0, null, $previous);
     }
 
+    /**
+     * The JSON body of Anikeen ID's error response, null without one. Some errors carry details,
+     * e.g. `net_amount` of "elapsed_amount_exceeded".
+     */
+    public function body(): ?object
+    {
+        $previous = $this->getPrevious();
+        $response = $previous !== null && method_exists($previous, 'getResponse') ? $previous->getResponse() : null;
+
+        if (!$response instanceof ResponseInterface) {
+            return null;
+        }
+
+        $body = json_decode((string) $response->getBody());
+
+        return is_object($body) ? $body : null;
+    }
+
     public function isNotFound(): bool
     {
         return $this->status === 404;
@@ -54,6 +79,16 @@ class ApiException extends ResourceException
         return $this->status === 409;
     }
 
+    /**
+     * A charge was refused because it would take the user's open monthly bill above their billing
+     * limit (409 "billing_limit_reached"). body() has limit, used, remaining, remaining_net,
+     * required, currency and resets_at.
+     */
+    public function isBillingLimitReached(): bool
+    {
+        return $this->status === 409 && $this->error === 'billing_limit_reached';
+    }
+
     /**
      * The ID service could not be reached (network error, timeout) or failed (5xx): retry later.
      */

src/Id/Exceptions/PreconditionFailedException.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Anikeen\Id\Exceptions;
+
+/**
+ * A conditional write failed (412): the stored version wasn't the one sent with `If-Match`
+ * ("preference_version_mismatch"), or the key was already set and the write was create-only
+ * ("preference_exists"). Reload, merge and retry with currentVersion().
+ */
+class PreconditionFailedException extends ApiException
+{
+    /**
+     * The version stored now, null when the key isn't set (or Anikeen ID didn't send one).
+     */
+    public function currentVersion(): ?int
+    {
+        $version = $this->body()->current_version ?? null;
+
+        return is_numeric($version) ? (int) $version : null;
+    }
+}

src/Id/Resources/AppCharge.php

@@ -0,0 +1,139 @@
+<?php
+
+namespace Anikeen\Id\Resources;
+
+use DateTimeImmutable;
+use JsonSerializable;
+
+/**
+ * A charge a trusted app booked onto a user's open monthly bill, see
+ * AnikeenId::createChargeForUser(). Amounts are decimal strings (`unit_price` with six decimals,
+ * the others with two).
+ *
+ * @property string $object "charge"
+ * @property string $id
+ * @property string $user_id
+ * @property string $status open (its bill is open), billed (the bill was closed) or voided
+ * @property string $idempotency_key
+ * @property string $name the line on the bill
+ * @property ?string $description
+ * @property string $type digital, physical or physical-reduced (the VAT treatment)
+ * @property int $quantity
+ * @property string $unit "piece"
+ * @property string $unit_price net per piece
+ * @property string $net_amount
+ * @property string $gross_amount what the charge added to the bill, VAT included
+ * @property string $currency_iso
+ * @property ?string $group
+ * @property string $occurred_at the line's service date (ISO 8601)
+ * @property ?string $reference the app's own id
+ * @property object $metadata the app's own data (string values)
+ * @property ?string $order_id the monthly bill (order) the line is on; follows the line when a rollover moves it
+ * @property ?string $voided_at
+ * @property ?string $void_reason
+ * @property string $created_at
+ */
+class AppCharge implements JsonSerializable
+{
+    public const STATUS_OPEN = 'open';
+
+    public const STATUS_BILLED = 'billed';
+
+    public const STATUS_VOIDED = 'voided';
+
+    public function __construct(protected object $data)
+    {
+    }
+
+    public function __get(string $name): mixed
+    {
+        return $this->data->{$name} ?? null;
+    }
+
+    public function __isset(string $name): bool
+    {
+        return isset($this->data->{$name});
+    }
+
+    public function id(): string
+    {
+        return $this->data->id;
+    }
+
+    /**
+     * open, billed or voided (the STATUS_* constants).
+     */
+    public function status(): string
+    {
+        return $this->data->status;
+    }
+
+    /**
+     * Its bill is still open: the charge can be voided.
+     */
+    public function isOpen(): bool
+    {
+        return $this->status() === self::STATUS_OPEN;
+    }
+
+    /**
+     * Its bill was closed (paid, waiting for payment or cancelled): only a refund of the order by
+     * Anikeen credits it.
+     */
+    public function isBilled(): bool
+    {
+        return $this->status() === self::STATUS_BILLED;
+    }
+
+    public function isVoided(): bool
+    {
+        return $this->status() === self::STATUS_VOIDED;
+    }
+
+    /**
+     * Net, e.g. "8.00".
+     */
+    public function netAmount(): string
+    {
+        return $this->data->net_amount;
+    }
+
+    /**
+     * Gross, what the charge added to the bill, e.g. "9.52".
+     */
+    public function grossAmount(): string
+    {
+        return $this->data->gross_amount;
+    }
+
+    /**
+     * The monthly bill (order) the charge is on, null once its line is gone (voided).
+     */
+    public function orderId(): ?string
+    {
+        return $this->data->order_id ?? null;
+    }
+
+    /**
+     * @return array<string, string>
+     */
+    public function metadata(): array
+    {
+        return (array) ($this->data->metadata ?? []);
+    }
+
+    public function occurredAt(): ?DateTimeImmutable
+    {
+        return isset($this->data->occurred_at) ? new DateTimeImmutable($this->data->occurred_at) : null;
+    }
+
+    public function toArray(): array
+    {
+        return (array) $this->data;
+    }
+
+    public function jsonSerialize(): array
+    {
+        return $this->toArray();
+    }
+}

src/Id/Resources/AppCheckoutSessions.php

@@ -36,7 +36,12 @@ class AppCheckoutSessions
      *         predecessor_id?: null|string,
      *         vat_rate?: float,
      *         payload?: null|array,
-     *         ends_at?: null|string
+     *         ends_at?: null|string,
+     *         trial_days?: null|int,
+     *         trial_ends_at?: null|string,
+     *         trial_once?: bool,
+     *         trial_payment_method?: null|string,
+     *         discount?: null|array{label: string, percent_off?: float|string, amount_off?: float|string, duration: string, duration_in_periods?: int}
      *     }>,
      *     return_url?: null|string,
      *     metadata?: null|array,
@@ -45,6 +50,11 @@ class AppCheckoutSessions
      * } $attributes return_url must share scheme, host and port with one of the app's redirect
      *               URIs; the user comes back to it with `status` and `checkout_session`. A
      *               repeated idempotency_key returns the first session instead of a new one.
+     *               trial_days / trial_ends_at give a subscription a free trial from the user's
+     *               confirmation on; trial_once is allowed on one subscription per group.
+     *               trial_payment_method `optional`: the session can be confirmed without a
+     *               payment method only if all of its subscriptions are such trials.
+     *               discount: see AppSubscriptions::create(); the confirmation page shows it.
      *
      * @throws ApiException 422 validation (e.g. return_url), 409 "idempotency_key_conflict"
      */

src/Id/Resources/AppOrders.php

@@ -13,9 +13,22 @@ use Illuminate\Database\Eloquent\Model;
  * scope orders:client) - of one user ($user->appOrders()) or of all users
  * (app(AnikeenId::class)->appOrders()). Nothing is requested until a method is called.
  *
- * Each order is an object with id, user_id, group, status (processing|pending|completed|cancelled),
+ * Each order is an object with id, user_id, oauth_client_id (the app that bills it: collective
- * is_collective, net_total, vat_total, gross_total, currency_iso, created_at, paid_at,
+ * orders are kept per app, even for the same group; null on legacy orders that billed several
- * payment_attempts, next_payment_attempt_at and last_payment_error ({code, message} or null).
+ * apps), group, metadata, status (processing|pending|completed|cancelled), is_collective,
+ * net_total, vat_total, gross_total, currency_iso, created_at, paid_at, payment_attempts,
+ * next_payment_attempt_at, last_payment_error ({code, message} or null), and
+ *
+ * - items: the order's lines of the app's subscriptions (all lines, except on legacy orders that
+ *   also billed other apps), each {id, name, description, type, image_url, units, unit,
+ *   price, vat_rate, subscription_id, meter, monthly_cap, discount, period_start, period_end,
+ *   net_amount, vat_amount, gross_amount}. period_end is exclusive (the start of the next
+ *   period); both are null for lines without a period. discount ({label, percent_off,
+ *   amount_off}) marks the negative line of a subscription's discount, else null. The net amount
+ *   a subscription was billed is the sum of net_amount of its lines.
+ * - invoice: null until the order is paid, then {id, number, type, status (pending while the PDF
+ *   is being rendered, then completed), service_period_from, service_period_to, created_at,
+ *   pdf_url}; see invoicePdf().
  */
 class AppOrders
 {
@@ -81,6 +94,22 @@ class AppOrders
         return !$this->billable || $order->user_id === $this->userId() ? $order : null;
     }
 
+    /**
+     * The PDF of an order's invoice (binary string, with the embedded e-invoice), the same as its
+     * `invoice.pdf_url` with the app's token.
+     *
+     * @throws ApiException 404 "order_not_found", 404 "invoice_not_found" (not paid yet),
+     *                      409 "invoice_not_ready" (still being rendered, try again later)
+     */
+    public function invoicePdf(string $orderId): string
+    {
+        if ($this->billable && !$this->find($orderId)) {
+            throw new ApiException('Order not found.', 404, 'order_not_found');
+        }
+
+        return (string) AppRequest::send('GET', sprintf('v1/client/orders/%s/invoice', $orderId))->response()?->getBody();
+    }
+
     private function userId(): string
     {
         return (new AppSubscriptions($this->billable))->userId();

src/Id/Resources/AppSubscription.php

@@ -6,6 +6,7 @@ use Anikeen\Id\Concerns\HasSubscriptionStatus;
 use Anikeen\Id\Exceptions\ApiException;
 use Anikeen\Id\Support\AppRequest;
 use DateTimeInterface;
+use InvalidArgumentException;
 use JsonSerializable;
 
 /**
@@ -28,6 +29,9 @@ use JsonSerializable;
  * @property ?string $status draft, trial, active, paused, cancelling, expired or cancelled, see status()
  * @property ?string $cancels_at when a scheduled cancellation takes effect
  * @property ?string $trial_ends_at
+ * @property ?string $trial_payment_method required or optional with a trial (TrialPaymentMethod), null without
+ * @property ?string $cancellation_reason why the billing cancelled it (CancellationReason), null otherwise
+ * @property ?object $discount {label, percent_off, amount_off, duration, duration_in_periods, periods_remaining}; periods_remaining is null for `forever`, 0 once it ended
  * @property ?string $starts_at
  * @property ?string $ends_at
  * @property ?string $accounting_at
@@ -36,11 +40,18 @@ use JsonSerializable;
  * @property ?array $payload
  * @property ?string $idempotency_key
  * @property ?string $checkout_session_id the checkout session the user confirms it in, if any
+ * @property ?object $scheduled_change {applies_at, name, description, unit, price, discount, created_at}: a change() for the period end
  */
 class AppSubscription implements JsonSerializable
 {
     use HasSubscriptionStatus;
 
+    /** change(): prorated, right away. */
+    public const APPLY_NOW = 'now';
+
+    /** change(): from the next period on (scheduled_change until then). */
+    public const APPLY_PERIOD_END = 'period_end';
+
     public function __construct(protected object $data)
     {
     }
@@ -59,6 +70,7 @@ class AppSubscription implements JsonSerializable
      * Change a subscription (send only what changes). Before checkout everything can change;
      * afterwards only the description, which names what the customer pays for and is shown
      * on their bills, e.g. `$subscription->update(['description' => 'web-01.example.com'])`.
+     * Prices of running subscriptions change with change().
      *
      * @throws ApiException
      */
@@ -67,21 +79,97 @@ class AppSubscription implements JsonSerializable
         return $this->send('PUT', '', $attributes);
     }
 
+    /**
+     * Change a running subscription (send only what changes), like a plan change:
+     *
+     * - `apply: now`: prorated – the unused rest of the current period is credited at the rate it
+     *   was billed at and charged at the new price on the user's open bill. A new unit starts a
+     *   new, fully billed period now. A downgrade whose credit exceeds the open bill is refused
+     *   (409 "credit_exceeds_bill"): schedule it for the period end instead.
+     * - `apply: period_end`: nothing changes now; the subscription has `scheduled_change` and the
+     *   next period is billed at the new values. A new scheduled change replaces the previous one.
+     *
+     * During a free trial nothing was billed, so both just change what the trial ends in.
+     * Webhook `subscription.updated` (with `data.previous_attributes`) when the change takes effect.
+     *
+     * @param array{
+     *     apply: string,
+     *     price?: float|string,
+     *     unit?: string,
+     *     name?: string,
+     *     description?: null|string,
+     *     discount?: null|array{label: string, percent_off?: float|string, amount_off?: float|string, duration: string, duration_in_periods?: int}
+     * } $attributes apply: self::APPLY_NOW or self::APPLY_PERIOD_END.
+     *               unit: a recurring unit (hour, day, week, month, year).
+     *               discount: replaces the discount from the next billed period on, null ends it;
+     *               required with a new unit when the current one counts in periods or is an
+     *               amount_off. Subscriptions with a monthly cap change only at the period end.
+     *
+     * @throws ApiException 409 "not_changeable" (not running: draft, paused, cancelling, …),
+     *                      "proration_not_possible", "credit_exceeds_bill",
+     *                      "billing_address_missing"; 422 validation
+     */
+    public function change(array $attributes): self
+    {
+        return $this->send('PUT', '/change', $attributes);
+    }
+
+    /**
+     * Drop the change scheduled for the period end (nothing happens without one).
+     *
+     * @throws ApiException
+     */
+    public function cancelScheduledChange(): self
+    {
+        return $this->send('DELETE', '/change');
+    }
+
     /**
      * Activate the subscription and bill its first period.
      *
      * $startsAt (in the past) books a service that is already running, e.g. a domain registered
      * earlier: the first period runs from $startsAt, is billed now and renews when it ends.
      *
-     * @throws ApiException 409 "already_active", "billing_address_missing", "period_already_ended", …
+     * A $startsAt older than one period is refused ("period_already_ended") unless
+     * $billElapsedPeriods is set: then the periods that have already ended are billed too, together
+     * with the running one, as long as they come to at most $maxNetAmount (net, up to two
+     * decimals) and $startsAt lies within the maximum age Anikeen ID accepts (about three years).
+     * The lines land on the current month's collective order, which is charged on the 1st of the
+     * next month. $billElapsedPeriods needs both $startsAt and $maxNetAmount.
+     *
+     * @throws ApiException 409 "already_active", "billing_address_missing", "period_already_ended",
+     *     "elapsed_periods_not_allowed" (the elapsed periods can't be billed for this subscription),
+     *     "elapsed_amount_exceeded" (they come to more than $maxNetAmount; the response body has
+     *     the booked `net_amount`), …; 422 invalid input (e.g. a start older than the maximum age)
+     * @throws InvalidArgumentException $billElapsedPeriods without $startsAt or $maxNetAmount
      */
-    public function checkout(DateTimeInterface|string|null $startsAt = null): self
+    public function checkout(
-    {
+        DateTimeInterface|string|null $startsAt = null,
+        bool $billElapsedPeriods = false,
+        float|string|null $maxNetAmount = null,
+    ): self {
         if ($startsAt instanceof DateTimeInterface) {
             $startsAt = $startsAt->format(DateTimeInterface::ATOM);
         }
 
-        return $this->send('PUT', '/checkout', $startsAt === null ? null : ['starts_at' => $startsAt]);
+        if (!$billElapsedPeriods) {
+            return $this->send('PUT', '/checkout', $startsAt === null ? null : ['starts_at' => $startsAt]);
+        }
+
+        if ($startsAt === null || $startsAt === '') {
+            throw new InvalidArgumentException('Billing elapsed periods needs a start date ($startsAt).');
+        }
+
+        if ($maxNetAmount === null || $maxNetAmount === '') {
+            throw new InvalidArgumentException('Billing elapsed periods needs a maximum net amount ($maxNetAmount).');
+        }
+
+        return $this->send('PUT', '/checkout', [
+            'starts_at' => $startsAt,
+            'bill_elapsed_periods' => true,
+            // floats from calculations may carry binary noise (e.g. 59.970000000000006)
+            'max_net_amount' => is_float($maxNetAmount) ? round($maxNetAmount, 2) : $maxNetAmount,
+        ]);
     }
 
     /**

src/Id/Resources/AppSubscriptions.php

@@ -49,6 +49,11 @@ class AppSubscriptions
      *     vat_rate?: float,
      *     payload?: null|array,
      *     ends_at?: null|string,
+     *     trial_days?: null|int,
+     *     trial_ends_at?: null|string,
+     *     trial_once?: bool,
+     *     trial_payment_method?: null|string,
+     *     discount?: null|array{label: string, percent_off?: float|string, amount_off?: float|string, duration: string, duration_in_periods?: int},
      *     idempotency_key?: null|string
      * } $attributes With an idempotency_key (max. 191 characters), a retried call returns the
      *               subscription created by the first one instead of a duplicate.
@@ -56,8 +61,21 @@ class AppSubscriptions
      *               at most 2 decimals, not below price; null = no cap).
      *               predecessor_id: the subscription this one replaces (a resize; same user and
      *               app, checked out, not cancelled): both share the monthly cap within a month.
+     *               trial_days: a free trial of 1–365 days from the checkout on (status `trial`,
+     *               nothing billed; the first period is billed when it ends), or
+     *               trial_ends_at: a fixed end of the trial (ISO 8601, in the future), not both.
+     *               trial_once: refuse the trial if the user already had one with the app in the
+     *               same group (422 here, 409 "trial_already_used" on checkout).
+     *               trial_payment_method: TrialPaymentMethod::REQUIRED (default) or ::OPTIONAL,
+     *               only with a trial: with `optional` the user may confirm it without a payment
+     *               method, and without one at the trial's end it is cancelled instead of billed.
+     *               discount: e.g. a coupon, as a negative line next to each billed period:
+     *               label (shown to the user, max. 100 characters), percent_off (0.01–100) or
+     *               amount_off (net per period, at most the price), duration `once` (the first
+     *               billed period), `repeating` (duration_in_periods billed periods) or
+     *               `forever`. Not combinable with a monthly_cap.
      *
-     * @throws ApiException
+     * @throws ApiException 422 validation, 409 "idempotency_key_conflict", …
      */
     public function create(array $attributes): AppSubscription
     {

src/Id/Resources/BillingLimit.php

@@ -0,0 +1,186 @@
+<?php
+
+namespace Anikeen\Id\Resources;
+
+use DateTimeImmutable;
+use JsonSerializable;
+
+/**
+ * A user's monthly billing limit: one gross limit for their whole open monthly bill across all
+ * Anikeen services, see AnikeenId::billingLimitForUser() and the `billing_limit` key of
+ * billingOverview(). Amounts are decimal strings with two decimals.
+ *
+ * Without a limit `limit`, `remaining` and `remaining_net` are null; for an app `used` is null
+ * too (an app sees the user's whole open bill only while they have set a limit). `used_by_app`
+ * (the open bills of your app) is there only when an app reads the limit.
+ *
+ * @property string $object "billing_limit"
+ * @property string $user_id
+ * @property string $currency "EUR"
+ * @property string $basis "gross"
+ * @property ?string $limit
+ * @property ?string $used the user's open monthly bills across all Anikeen services
+ * @property ?string $used_by_app the open monthly bills of your app (app reads only)
+ * @property ?string $remaining max(0, limit − used)
+ * @property ?string $remaining_net remaining at the user's VAT rate, rounded down (a hint)
+ * @property int|float|null $vat_rate null without a billing address
+ * @property bool $reached used >= limit: start no new paid service
+ * @property string $resets_at when this month's bills are closed (ISO 8601)
+ * @property int $version only goes up; keep the highest seen (also in the billing_limit.* webhooks)
+ */
+class BillingLimit implements JsonSerializable
+{
+    public function __construct(protected object $data)
+    {
+    }
+
+    public function __get(string $name): mixed
+    {
+        return $this->data->{$name} ?? null;
+    }
+
+    public function __isset(string $name): bool
+    {
+        return isset($this->data->{$name});
+    }
+
+    /**
+     * The user has set a limit (`0.00` is one too: no new charges at all).
+     */
+    public function hasLimit(): bool
+    {
+        return $this->limit() !== null;
+    }
+
+    /**
+     * Gross, null without a limit.
+     */
+    public function limit(): ?string
+    {
+        return $this->data->limit ?? null;
+    }
+
+    /**
+     * The user's open monthly bills across all Anikeen services (gross). Null for an app while the
+     * user has no limit.
+     */
+    public function used(): ?string
+    {
+        return $this->data->used ?? null;
+    }
+
+    /**
+     * The open monthly bills of your app (gross); null outside an app read (billingOverview()).
+     * `used − used_by_app` is what the user spends on their other Anikeen services.
+     */
+    public function usedByApp(): ?string
+    {
+        return $this->data->used_by_app ?? null;
+    }
+
+    /**
+     * Gross room left (never negative), null without a limit.
+     */
+    public function remaining(): ?string
+    {
+        return $this->data->remaining ?? null;
+    }
+
+    /**
+     * The room left as a net amount at the user's VAT rate, rounded down: a hint only (the VAT of
+     * a charge depends on its type). Null without a limit or a billing address.
+     */
+    public function remainingNet(): ?string
+    {
+        return $this->data->remaining_net ?? null;
+    }
+
+    /**
+     * The user's VAT rate in percent (e.g. 19.0), null without a billing address.
+     */
+    public function vatRate(): ?float
+    {
+        return isset($this->data->vat_rate) ? (float) $this->data->vat_rate : null;
+    }
+
+    public function currency(): string
+    {
+        return $this->data->currency ?? 'EUR';
+    }
+
+    /**
+     * The limit is reached (used >= limit): start no new paid service for the user.
+     */
+    public function isReached(): bool
+    {
+        return (bool) ($this->data->reached ?? false);
+    }
+
+    /**
+     * When this month's bills are closed and `used` drops.
+     */
+    public function resetsAt(): ?DateTimeImmutable
+    {
+        return isset($this->data->resets_at) ? new DateTimeImmutable($this->data->resets_at) : null;
+    }
+
+    /**
+     * Only goes up: keep the highest one seen and ignore webhooks with a lower or equal one.
+     */
+    public function version(): int
+    {
+        return (int) ($this->data->version ?? 0);
+    }
+
+    /**
+     * Whether a charge of $gross (gross, e.g. "4.76") would fit as of this read: always without a
+     * limit, else at most `remaining`. Advisory only: it reserves nothing, the binding check is
+     * the booking (409 "billing_limit_reached").
+     */
+    public function allows(string|int|float $gross): bool
+    {
+        if (!$this->hasLimit()) {
+            return true;
+        }
+
+        $remaining = $this->remaining();
+
+        return $remaining !== null && self::compare($gross, $remaining) <= 0;
+    }
+
+    public function toArray(): array
+    {
+        return (array) $this->data;
+    }
+
+    public function jsonSerialize(): array
+    {
+        return $this->toArray();
+    }
+
+    /**
+     * Compares two non-negative decimal amounts exactly (as digit strings, no float rounding);
+     * negative amounts count as zero.
+     */
+    private static function compare(string|int|float $a, string|int|float $b): int
+    {
+        return strcmp(self::micros($a), self::micros($b)) <=> 0;
+    }
+
+    /**
+     * The amount in millionths as a zero-padded digit string of a fixed width.
+     */
+    private static function micros(string|int|float $amount): string
+    {
+        $amount = is_float($amount) ? number_format($amount, 6, '.', '') : trim((string) $amount);
+
+        if (str_starts_with($amount, '-')) {
+            return str_repeat('0', 40);
+        }
+
+        [$whole, $fraction] = array_pad(explode('.', ltrim($amount, '+'), 2), 2, '');
+        $digits = preg_replace('/\D/', '', $whole) . substr(str_pad(preg_replace('/\D/', '', $fraction), 6, '0'), 0, 6);
+
+        return str_pad(ltrim($digits, '0'), 40, '0', STR_PAD_LEFT);
+    }
+}

src/Id/Resources/Order.php

@@ -8,7 +8,14 @@ use Throwable;
 
 /**
  * @property string $id
- * @property null|string $confirmation_url where the user confirms it (third-party apps)
+ * @property null|string $confirmation_url where the user confirms it (third-party apps, or `confirm`)
+ * @property null|string $oauth_client_id the app that bills the order: the app that created it, or for a monthly
+ *                                        (collective) order the app whose subscriptions it bills; collective orders
+ *                                        are kept per app. null for Anikeen's own (and legacy orders of several apps)
+ * @property null|string $group
+ * @property null|object $metadata the app's own data, returned as is
+ * @property null|string $return_url where the user returns after confirming
+ * @property null|string $expires_at when a draft created with `confirm` is cancelled unless confirmed
  */
 class Order extends BaseResource
 {
@@ -53,10 +60,14 @@ class Order extends BaseResource
      *           country_iso: string,
      *           phone_number: null|string,
      *           email: null|string
-     *      }
+     *      },
+     *      group?: null|string,
+     *      metadata?: null|array
      *  } $attributes The order data:
      *    - billing_address:  Billing address (ISO 3166-1 alpha-2 country code)
      *    - shipping_address: Shipping address for physical items (first name, last name, address, postal code, city, ISO 3166-1 alpha-2 country code)
+     *    - group:            The app's group (optional)
+     *    - metadata:         The app's own data (max. 50 keys), only while the order is a draft (optional)
      * @throws Throwable
      */
     public function update(array $attributes = []): self
@@ -69,6 +80,8 @@ class Order extends BaseResource
     /**
      * Checkout given order from the current user.
      *
+     * A draft created with `confirm` can't be checked out once it expired (409 "confirmation_expired").
+     *
      * @throws Throwable
      */
     public function checkout(): self

src/Id/Resources/Orders.php

@@ -48,6 +48,10 @@ class Orders extends BaseCollection
      *          phone_number: null|string,
      *          email: null|string
      *     },
+     *     group?: null|string,
+     *     confirm?: bool,
+     *     return_url?: null|string,
+     *     metadata?: null|array,
      *     items: array<array{
      *         type:         string,
      *         name:         string,
@@ -61,6 +65,10 @@ class Orders extends BaseCollection
      * } $attributes The order data:
      *   - billing_address:  Billing address (ISO 3166-1 alpha-2 country code)
      *   - shipping_address: Shipping address for physical items (first name, last name, address, postal code, city, ISO 3166-1 alpha-2 country code)
+     *   - group:            The app's group, e.g. a team (optional)
+     *   - confirm:          Trusted apps: leave confirming and paying to the user (confirmation_url, expires after 24 hours; optional)
+     *   - return_url:       Where the user returns after confirming (same origin as one of the app's redirect URIs; optional)
+     *   - metadata:         The app's own data (max. 50 keys), returned as is in the API and webhooks (optional)
      *   - items:            Array of order items:
      *       - type:        digital, physical or physical-reduced (VAT category)
      *       - price/gross_price: net or gross unit price, one of both

src/Id/Resources/Preference.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace Anikeen\Id\Resources;
+
+/**
+ * A preference of a user: a JSON value under a namespace and a key. `version` is opaque: it only
+ * goes up (per user, not consecutive per key) and is what ifVersion (`If-Match`) compares.
+ * JSON objects come back as stdClass, so `{}` stays an object.
+ *
+ * @property string $namespace
+ * @property string $key
+ * @property mixed $value
+ * @property int $version
+ * @property string $updated_at
+ * @property object{type: string, client_id: ?string} $updated_by `type` "user" (written with a user token) or "app"
+ */
+class Preference extends BaseResource
+{
+    /**
+     * The write that returned this preference created the key (201). False for reads, updates and
+     * writes of the value already stored.
+     */
+    public function wasCreated(): bool
+    {
+        return $this->result->response()?->getStatusCode() === 201;
+    }
+}

src/Id/Resources/Preferences.php

@@ -0,0 +1,68 @@
+<?php
+
+namespace Anikeen\Id\Resources;
+
+/**
+ * The preferences of a user in one namespace, sorted by key (at most 50, no pagination).
+ */
+class Preferences extends BaseCollection
+{
+    /**
+     * The preference of a key; null when it isn't set. Reads the list, no request.
+     */
+    public function find(string $id): ?Preference
+    {
+        $data = $this->item($id);
+
+        if ($data === null) {
+            return null;
+        }
+
+        $result = clone $this->result;
+        $result->data = $data;
+
+        return new Preference(fn () => $result);
+    }
+
+    /**
+     * The value of a key, or $default when it isn't set.
+     */
+    public function get(string $key, mixed $default = null): mixed
+    {
+        $data = $this->item($key);
+
+        return $data !== null ? $data->value : $default;
+    }
+
+    public function has(string $key): bool
+    {
+        return $this->item($key) !== null;
+    }
+
+    /**
+     * The values by key.
+     *
+     * @return array<string, mixed>
+     */
+    public function values(): array
+    {
+        $values = [];
+
+        foreach ((array) $this->result->data as $data) {
+            $values[$data->key] = $data->value;
+        }
+
+        return $values;
+    }
+
+    private function item(string $key): ?object
+    {
+        foreach ((array) $this->result->data as $data) {
+            if (($data->key ?? null) === $key) {
+                return $data;
+            }
+        }
+
+        return null;
+    }
+}

src/Id/Resources/Subscription.php

@@ -27,6 +27,9 @@ use Throwable;
  * @property string $ends_at
  * @property ?string $cancels_at when a scheduled cancellation takes effect
  * @property ?string $trial_ends_at
+ * @property ?string $trial_payment_method required or optional with a trial (TrialPaymentMethod), null without
+ * @property ?string $cancellation_reason why the billing cancelled it (CancellationReason), null otherwise
+ * @property ?object $discount {label, percent_off, amount_off, duration, duration_in_periods, periods_remaining}; periods_remaining is null for `forever`, 0 once it ended
  * @property null|string $confirmation_url where the user confirms it (third-party apps)
  */
 class Subscription extends BaseResource

src/Id/Resources/Subscriptions.php

@@ -24,7 +24,12 @@ class Subscriptions extends BaseCollection
      *      predecessor_id?: null|string,
      *      vat_rate: float,
      *      payload: null|array,
-     *      ends_at: null|string
+     *      ends_at: null|string,
+     *      trial_days?: null|int,
+     *      trial_ends_at?: null|string,
+     *      trial_once?: bool,
+     *      trial_payment_method?: null|string,
+     *      discount?: null|array{label: string, percent_off?: float|string, amount_off?: float|string, duration: string, duration_in_periods?: int}
      *  } $attributes The subscription data:
      *    - group:          The group (optional)
      *    - name:           The name
@@ -36,6 +41,11 @@ class Subscriptions extends BaseCollection
      *    - vat_rate:       The VAT rate (required when set)
      *    - payload:        The payload (optional)
      *    - ends_at:        The end date (optional)
+     *    - trial_days:     A free trial of 1–365 days from the user's confirmation on (optional)
+     *    - trial_ends_at:  Or a fixed end of the free trial (ISO 8601, in the future; optional)
+     *    - trial_once:     Refuse the trial if the user already had one with the app in the group (optional)
+     *    - trial_payment_method: TrialPaymentMethod::REQUIRED (default) or ::OPTIONAL, only with a trial (optional)
+     *    - discount:       A discount per billed period, see AppSubscriptions::create() (optional)
      * @throws Throwable
      */
     public function create(array $attributes): Subscription

src/Id/Support/AppRequest.php

@@ -5,36 +5,40 @@ namespace Anikeen\Id\Support;
 use Anikeen\Id\AnikeenId;
 use Anikeen\Id\Contracts\AppTokenRepository;
 use Anikeen\Id\Exceptions\ApiException;
+use Anikeen\Id\Exceptions\PreconditionFailedException;
 use Anikeen\Id\Result;
 use GuzzleHttp\Exception\GuzzleException;
 use Throwable;
 
 /**
  * Sends a request with the app's own token (client credentials). A rejected token is renewed
- * once; every failure ends in an ApiException with status and error code.
+ * once; every failure ends in an ApiException with status and error code (a 412 in a
+ * PreconditionFailedException).
  */
 final class AppRequest
 {
     /**
+     * @param array<string, string> $headers Extra request headers, e.g. `If-Match`.
      * @throws ApiException
      */
-    public static function send(string $method, string $path, ?array $payload = null, array $query = []): Result
+    public static function send(string $method, string $path, ?array $payload = null, array $query = [], array $headers = []): Result
     {
-        $result = self::attempt($method, $path, $payload, $query);
+        $result = self::attempt($method, $path, $payload, $query, $headers);
 
         if ($result->status === 401) {
             $tokens = app(AppTokenRepository::class);
 
             if (method_exists($tokens, 'forgetAccessToken')) {
                 $tokens->forgetAccessToken();
-                $result = self::attempt($method, $path, $payload, $query);
+                $result = self::attempt($method, $path, $payload, $query, $headers);
             }
         }
 
         if (!$result->success()) {
             $body = is_object($result->data) ? $result->data : null;
+            $exception = $result->status === 412 ? PreconditionFailedException::class : ApiException::class;
 
-            throw new ApiException(
+            throw new $exception(
                 sprintf('Anikeen ID request %s %s failed: %s', $method, $path, $body->message ?? $result->error()),
                 $result->response()?->getStatusCode() ?? 0,
                 $body->error ?? null,
@@ -48,10 +52,10 @@ final class AppRequest
     /**
      * @throws ApiException
      */
-    private static function attempt(string $method, string $path, ?array $payload, array $query): Result
+    private static function attempt(string $method, string $path, ?array $payload, array $query, array $headers = []): Result
     {
         try {
-            return app(AnikeenId::class)->asApp()->request($method, $path, $payload, $query);
+            return app(AnikeenId::class)->asApp()->request($method, $path, $payload, $query, null, false, $headers);
         } catch (ApiException $e) {
             throw $e;
         } catch (GuzzleException|Throwable $e) {

src/Id/Support/PreferenceRequest.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Anikeen\Id\Support;
+
+use InvalidArgumentException;
+
+/**
+ * @internal paths and preconditions of the preferences API
+ */
+final class PreferenceRequest
+{
+    /**
+     * The path with every segment URL-encoded, e.g. path('v1/preferences', 'global', 'appearance').
+     */
+    public static function path(string $base, string ...$segments): string
+    {
+        return $base . '/' . implode('/', array_map('rawurlencode', $segments));
+    }
+
+    /**
+     * `If-Match: "<version>"` (only if the stored version is this one) or `If-None-Match: *`
+     * (only if the key isn't set yet).
+     *
+     * @return array<string, string>
+     */
+    public static function conditions(?int $ifVersion, bool $createOnly = false): array
+    {
+        if ($ifVersion !== null && $createOnly) {
+            throw new InvalidArgumentException('A write is either conditional on a version or create-only, not both.');
+        }
+
+        return match (true) {
+            $ifVersion !== null => ['If-Match' => sprintf('"%d"', $ifVersion)],
+            $createOnly => ['If-None-Match' => '*'],
+            default => [],
+        };
+    }
+
+    private function __construct()
+    {
+    }
+}

src/Id/Webhooks/EventType.php

@@ -13,14 +13,45 @@ final class EventType
     public const ORDER_PAYMENT_FAILED = 'order.payment_failed';
     public const ORDER_CANCELLED = 'order.cancelled';
     public const ORDER_SHIPPED = 'order.shipped';
+    /**
+     * Money was given back for an order (a refund or a partial cancellation, with a credit note);
+     * see the order's `refunds` and `refunded_total`. A full refund also cancels the order,
+     * so order.cancelled is sent too; don't rely on the order of the two events.
+     */
+    public const ORDER_REFUNDED = 'order.refunded';
 
     public const SUBSCRIPTION_CREATED = 'subscription.created';
     public const SUBSCRIPTION_ACTIVATED = 'subscription.activated';
     public const SUBSCRIPTION_PAUSED = 'subscription.paused';
     public const SUBSCRIPTION_RESUMED = 'subscription.resumed';
+    /** `data.reason`: why the billing cancelled it (CancellationReason, e.g. a trial that ended without a payment method), else null. */
     public const SUBSCRIPTION_CANCELLED = 'subscription.cancelled';
     public const SUBSCRIPTION_EXPIRED = 'subscription.expired';
 
+    /**
+     * The free trial of a running subscription ends in a few days (see trial_ends_at); billing
+     * starts then. `data.payment_method_missing`: the user has no payment method yet (with
+     * trial_payment_method `optional` the subscription then ends with the trial).
+     */
+    public const SUBSCRIPTION_TRIAL_WILL_END = 'subscription.trial_will_end';
+
+    /** The last discounted period of a subscription was billed; the following ones are billed at the full price. */
+    public const SUBSCRIPTION_DISCOUNT_ENDED = 'subscription.discount_ended';
+
+    /**
+     * The price, unit, name, description or discount of a running subscription changed (right away
+     * or at the period end); `data.previous_attributes` has the changed fields' old values.
+     */
+    public const SUBSCRIPTION_UPDATED = 'subscription.updated';
+
+    /**
+     * A period of a subscription was booked on its collective order, the first one included;
+     * `data.period` describes it, `data.period.first_period` is true for the subscription's first
+     * paid period (checkout or the end of a free trial). Opt-in: only endpoints that select this
+     * event get it (not through `*`).
+     */
+    public const SUBSCRIPTION_RENEWED = 'subscription.renewed';
+
     /** The user confirmed a checkout session: all of its subscriptions are running (sent after their subscription.activated). */
     public const CHECKOUT_COMPLETED = 'checkout.completed';
 
@@ -30,6 +61,21 @@ final class EventType
     /** A checkout session was not confirmed within 24 hours; its drafts were cancelled. */
     public const CHECKOUT_EXPIRED = 'checkout.expired';
 
+    /**
+     * A user's open monthly bill reached their billing limit: start no new paid service for them.
+     * `data.object` is the billing limit as the app reads it (with `version`), `data.reason`
+     * `booking` or `limit_changed`. Opt-in: only endpoints that select this event get it (not
+     * through `*`), and only apps that may read the limit of a user connected to them.
+     */
+    public const BILLING_LIMIT_REACHED = 'billing_limit.reached';
+
+    /**
+     * A user whose billing limit was reached has room again. `data.object` is the billing limit
+     * (with `version`), `data.reason` `limit_changed`, `limit_removed`, `voided`, `period_reset`
+     * or `order_changed`. Opt-in like BILLING_LIMIT_REACHED.
+     */
+    public const BILLING_LIMIT_AVAILABLE = 'billing_limit.available';
+
     public const TEST = 'webhook.test';
 
     /**

tests/Id/AppChargesTest.php

@@ -0,0 +1,269 @@
+<?php
+
+namespace Anikeen\Id\Tests;
+
+use Anikeen\Id\AnikeenId;
+use Anikeen\Id\Exceptions\ApiException;
+use Anikeen\Id\Resources\AppCharge;
+use Anikeen\Id\Resources\BillingLimit;
+use DateTimeImmutable;
+
+class AppChargesTest extends TestCase
+{
+    private function sentCall(int $index): string
+    {
+        $request = $this->sent[$index]['request'];
+
+        return $request->getMethod() . ' ' . $request->getUri()->getPath() . ' ' . $request->getHeaderLine('Authorization');
+    }
+
+    private function charge(array $overrides = []): array
+    {
+        return ['data' => [
+            'object' => 'charge', 'id' => '01JCHARGE', 'user_id' => '01JUSER', 'status' => 'open',
+            'idempotency_key' => 'shipment-123', 'name' => 'Signed card', 'description' => null,
+            'type' => 'physical', 'quantity' => 2, 'unit' => 'piece', 'unit_price' => '4.000000',
+            'net_amount' => '8.00', 'gross_amount' => '9.52', 'currency_iso' => 'EUR', 'group' => null,
+            'occurred_at' => '2026-11-06T10:00:00+00:00', 'reference' => 'order-77', 'metadata' => ['parcel' => 'p-1'],
+            'order_id' => '01JORDER', 'voided_at' => null, 'void_reason' => null, 'created_at' => '2026-11-06T10:00:01+00:00',
+            ...$overrides,
+        ]];
+    }
+
+    private function limit(array $overrides = []): array
+    {
+        return ['data' => [
+            'object' => 'billing_limit', 'user_id' => '01JUSER', 'currency' => 'EUR', 'basis' => 'gross',
+            'limit' => '100.00', 'used' => '82.40', 'used_by_app' => '60.00', 'remaining' => '17.60',
+            'remaining_net' => '14.78', 'vat_rate' => 19, 'reached' => false,
+            'resets_at' => '2026-12-01T02:00:00Z', 'version' => 7,
+            ...$overrides,
+        ]];
+    }
+
+    public function test_a_charge_is_booked_with_the_app_token(): void
+    {
+        $this->respond(201, $this->charge());
+
+        $attributes = [
+            'idempotency_key' => 'shipment-123',
+            'name' => 'Signed card',
+            'type' => 'physical',
+            'quantity' => 2,
+            'unit_price' => '4.00',
+            'reference' => 'order-77',
+            'metadata' => ['parcel' => 'p-1'],
+        ];
+        $charge = app(AnikeenId::class)->createChargeForUser('01JUSER', $attributes);
+
+        $this->assertSame('POST /api/v1/client/users/01JUSER/charges Bearer app-token', $this->sentCall(0));
+        $this->assertSame($attributes, $this->sentJson(0));
+        $this->assertInstanceOf(AppCharge::class, $charge);
+        $this->assertSame('01JCHARGE', $charge->id());
+        $this->assertSame('open', $charge->status());
+        $this->assertTrue($charge->isOpen());
+        $this->assertFalse($charge->isBilled());
+        $this->assertFalse($charge->isVoided());
+        $this->assertSame('8.00', $charge->netAmount());
+        $this->assertSame('9.52', $charge->grossAmount());
+        $this->assertSame('01JORDER', $charge->orderId());
+        $this->assertSame(['parcel' => 'p-1'], $charge->metadata());
+        $this->assertEquals(new DateTimeImmutable('2026-11-06T10:00:00+00:00'), $charge->occurredAt());
+        $this->assertSame(2, $charge->quantity);
+        $this->assertSame('order-77', $charge->reference);
+        $this->assertNull($charge->voided_at);
+        $this->assertSame('Signed card', $charge->jsonSerialize()['name']);
+    }
+
+    public function test_empty_metadata_is_an_empty_array(): void
+    {
+        $this->respond(200, $this->charge(['metadata' => new \stdClass()]));
+
+        $this->assertSame([], app(AnikeenId::class)->findChargeForUser('01JUSER', '01JCHARGE')->metadata());
+    }
+
+    public function test_a_charge_is_found_with_the_app_token(): void
+    {
+        $this->respond(200, $this->charge(['status' => 'billed']));
+
+        $charge = app(AnikeenId::class)->findChargeForUser('01JUSER', '01JCHARGE');
+
+        $this->assertSame('GET /api/v1/client/users/01JUSER/charges/01JCHARGE Bearer app-token', $this->sentCall(0));
+        $this->assertTrue($charge->isBilled());
+    }
+
+    public function test_a_charge_is_voided_with_and_without_a_reason(): void
+    {
+        $voided = ['status' => 'voided', 'order_id' => null, 'voided_at' => '2026-11-06T11:00:00+00:00', 'void_reason' => 'Parcel lost'];
+        $this->respond(200, $this->charge($voided));
+        $this->respond(200, $this->charge($voided));
+
+        $charge = app(AnikeenId::class)->voidChargeForUser('01JUSER', '01JCHARGE', 'Parcel lost');
+        app(AnikeenId::class)->voidChargeForUser('01JUSER', '01JCHARGE');
+
+        $this->assertSame('POST /api/v1/client/users/01JUSER/charges/01JCHARGE/void Bearer app-token', $this->sentCall(0));
+        $this->assertSame(['reason' => 'Parcel lost'], $this->sentJson(0));
+        $this->assertSame('POST /api/v1/client/users/01JUSER/charges/01JCHARGE/void Bearer app-token', $this->sentCall(1));
+        $this->assertSame([], $this->sentJson(1));
+        $this->assertTrue($charge->isVoided());
+        $this->assertNull($charge->orderId());
+        $this->assertSame('Parcel lost', $charge->void_reason);
+    }
+
+    public function test_path_segments_are_encoded(): void
+    {
+        $this->respond(200, $this->charge());
+
+        app(AnikeenId::class)->findChargeForUser('01J/USER', '01J CHARGE');
+
+        $this->assertSame('/api/v1/client/users/01J%2FUSER/charges/01J%20CHARGE', $this->sent[0]['request']->getUri()->getPath());
+    }
+
+    public function test_a_charge_over_the_billing_limit_carries_the_details(): void
+    {
+        $this->respond(409, [
+            'message' => 'The customer\'s billing limit is reached.', 'error' => 'billing_limit_reached',
+            'limit' => '100.00', 'used' => '97.40', 'remaining' => '2.60', 'remaining_net' => '2.18',
+            'required' => '4.76', 'currency' => 'EUR', 'resets_at' => '2026-12-01T02:00:00Z',
+        ]);
+
+        try {
+            app(AnikeenId::class)->createChargeForUser('01JUSER', ['idempotency_key' => 'k', 'name' => 'Card', 'quantity' => 1, 'unit_price' => '4.00']);
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isBillingLimitReached());
+            $this->assertTrue($e->isConflict());
+            $this->assertSame(409, $e->status);
+            $this->assertSame('2.60', $e->body()->remaining);
+            $this->assertSame('4.76', $e->body()->required);
+            $this->assertSame('2026-12-01T02:00:00Z', $e->body()->resets_at);
+        }
+    }
+
+    public function test_other_conflicts_are_not_the_billing_limit(): void
+    {
+        $this->respond(409, ['message' => 'The charge is more than this app may charge at once.', 'error' => 'charge_exceeds_maximum', 'max_charge_net' => '50.00']);
+
+        try {
+            app(AnikeenId::class)->createChargeForUser('01JUSER', ['idempotency_key' => 'k', 'name' => 'Card', 'quantity' => 1, 'unit_price' => '60.00']);
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertFalse($e->isBillingLimitReached());
+            $this->assertSame('charge_exceeds_maximum', $e->error);
+            $this->assertSame('50.00', $e->body()->max_charge_net);
+        }
+    }
+
+    public function test_an_already_billed_charge_cannot_be_voided(): void
+    {
+        $this->respond(409, ['message' => 'The charge is on a closed bill; only a refund of that order credits it.', 'error' => 'charge_already_billed', 'charge_id' => '01JCHARGE']);
+
+        try {
+            app(AnikeenId::class)->voidChargeForUser('01JUSER', '01JCHARGE');
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertSame('charge_already_billed', $e->error);
+            $this->assertSame('01JCHARGE', $e->body()->charge_id);
+        }
+    }
+
+    public function test_an_unknown_charge_is_not_found(): void
+    {
+        $this->respond(404, ['message' => 'Charge not found.', 'error' => 'charge_not_found']);
+
+        try {
+            app(AnikeenId::class)->findChargeForUser('01JUSER', '01JOTHER');
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isNotFound());
+            $this->assertSame('charge_not_found', $e->error);
+        }
+    }
+
+    public function test_the_billing_limit_is_read_with_the_app_token(): void
+    {
+        $this->respond(200, $this->limit());
+
+        $limit = app(AnikeenId::class)->billingLimitForUser('01JUSER');
+
+        $this->assertSame('GET /api/v1/client/users/01JUSER/billing-limit Bearer app-token', $this->sentCall(0));
+        $this->assertInstanceOf(BillingLimit::class, $limit);
+        $this->assertTrue($limit->hasLimit());
+        $this->assertSame('100.00', $limit->limit());
+        $this->assertSame('82.40', $limit->used());
+        $this->assertSame('60.00', $limit->usedByApp());
+        $this->assertSame('17.60', $limit->remaining());
+        $this->assertSame('14.78', $limit->remainingNet());
+        $this->assertSame(19.0, $limit->vatRate());
+        $this->assertSame('EUR', $limit->currency());
+        $this->assertFalse($limit->isReached());
+        $this->assertEquals(new DateTimeImmutable('2026-12-01T02:00:00Z'), $limit->resetsAt());
+        $this->assertSame(7, $limit->version());
+        $this->assertSame('gross', $limit->basis);
+    }
+
+    public function test_without_a_limit_the_app_sees_only_its_own_share(): void
+    {
+        $this->respond(200, $this->limit(['limit' => null, 'used' => null, 'remaining' => null, 'remaining_net' => null, 'vat_rate' => null]));
+
+        $limit = app(AnikeenId::class)->billingLimitForUser('01JUSER');
+
+        $this->assertFalse($limit->hasLimit());
+        $this->assertNull($limit->limit());
+        $this->assertNull($limit->used());
+        $this->assertNull($limit->remaining());
+        $this->assertNull($limit->remainingNet());
+        $this->assertNull($limit->vatRate());
+        $this->assertSame('60.00', $limit->usedByApp());
+        $this->assertTrue($limit->allows('100000.00'));
+    }
+
+    public function test_allows_compares_with_the_remaining_amount(): void
+    {
+        $limit = new BillingLimit((object) $this->limit()['data']);
+
+        $this->assertTrue($limit->allows('17.60'));
+        $this->assertTrue($limit->allows('17.6'));
+        $this->assertTrue($limit->allows('4.76'));
+        $this->assertTrue($limit->allows(17.6));
+        $this->assertTrue($limit->allows(17));
+        $this->assertFalse($limit->allows('17.61'));
+        $this->assertFalse($limit->allows('17.600001'));
+        $this->assertFalse($limit->allows('100.00'));
+        $this->assertFalse($limit->allows(1000));
+    }
+
+    public function test_a_reached_or_zero_limit_allows_nothing(): void
+    {
+        $reached = new BillingLimit((object) $this->limit(['used' => '100.00', 'remaining' => '0.00', 'remaining_net' => '0.00', 'reached' => true])['data']);
+        $zero = new BillingLimit((object) $this->limit(['limit' => '0.00', 'used' => '0.00', 'remaining' => '0.00', 'reached' => true])['data']);
+
+        $this->assertTrue($reached->isReached());
+        $this->assertFalse($reached->allows('0.01'));
+        $this->assertTrue($zero->hasLimit());
+        $this->assertFalse($zero->allows('0.01'));
+    }
+
+    public function test_the_user_s_own_limit_has_no_app_share(): void
+    {
+        $limit = new BillingLimit((object) ['object' => 'billing_limit', 'user_id' => '01JUSER', 'currency' => 'EUR', 'basis' => 'gross', 'limit' => null, 'used' => '12.00', 'remaining' => null, 'remaining_net' => null, 'vat_rate' => 19.0, 'reached' => false, 'resets_at' => '2026-12-01T02:00:00Z', 'version' => 0]);
+
+        $this->assertSame('12.00', $limit->used());
+        $this->assertNull($limit->usedByApp());
+        $this->assertSame(0, $limit->version());
+    }
+
+    public function test_a_refused_limit_read_is_an_api_exception(): void
+    {
+        $this->respond(403, ['message' => 'This app may not read customers\' billing limits.', 'error' => 'billing_limit_not_enabled']);
+
+        try {
+            app(AnikeenId::class)->billingLimitForUser('01JUSER');
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertSame(403, $e->status);
+            $this->assertSame('billing_limit_not_enabled', $e->error);
+            $this->assertFalse($e->isBillingLimitReached());
+        }
+    }
+}

tests/Id/AppOrdersTest.php

@@ -4,6 +4,8 @@ namespace Anikeen\Id\Tests;
 
 use Anikeen\Id\AnikeenId;
 use Anikeen\Id\Billable;
+use Anikeen\Id\Exceptions\ApiException;
+use GuzzleHttp\Psr7\Response;
 use Illuminate\Database\Eloquent\Model;
 
 class AppOrdersTest extends TestCase
@@ -68,4 +70,65 @@ class AppOrdersTest extends TestCase
         $this->assertNull($orders->find('o1'));
         $this->assertSame('o1', $orders->find('o1')->id);
     }
+
+    public function test_orders_list_their_lines_and_invoice(): void
+    {
+        $this->respond(200, ['data' => [
+            'id' => 'o1',
+            'user_id' => '01JUSER',
+            'group' => 'team-1',
+            'metadata' => ['topup' => '7'],
+            'items' => [
+                ['id' => 'i1', 'subscription_id' => '01JSUB', 'units' => 1, 'price' => 10, 'period_start' => '2026-11-01T00:00:00+00:00', 'period_end' => '2026-12-01T00:00:00+00:00', 'net_amount' => 10, 'discount' => null],
+                ['id' => 'i2', 'subscription_id' => '01JSUB', 'units' => 1, 'price' => -2, 'period_start' => '2026-11-01T00:00:00+00:00', 'period_end' => '2026-12-01T00:00:00+00:00', 'net_amount' => -2, 'discount' => ['label' => 'SUMMER20', 'percent_off' => 20, 'amount_off' => null]],
+            ],
+            'invoice' => ['id' => 'inv1', 'number' => 'RE-2026-0001', 'status' => 'completed', 'pdf_url' => 'https://id.test/api/v1/client/orders/o1/invoice'],
+        ]]);
+
+        $order = $this->owner()->appOrders()->find('o1');
+
+        $this->assertSame('7', $order->metadata->topup);
+        $this->assertSame(8, array_sum(array_map(fn ($item) => $item->net_amount, array_filter($order->items, fn ($item) => $item->subscription_id === '01JSUB'))));
+        $this->assertSame('SUMMER20', $order->items[1]->discount->label);
+        $this->assertSame('RE-2026-0001', $order->invoice->number);
+    }
+
+    public function test_the_invoice_pdf_is_downloaded_with_the_app_token(): void
+    {
+        $this->http->append(new Response(200, ['Content-Type' => 'application/pdf'], '%PDF-1.7 invoice'));
+        $this->respond(200, ['data' => ['id' => 'o1', 'user_id' => '01JUSER']]);
+        $this->http->append(new Response(200, ['Content-Type' => 'application/pdf'], '%PDF-1.7 invoice'));
+
+        $this->assertSame('%PDF-1.7 invoice', app(AnikeenId::class)->appOrders()->invoicePdf('o1'));
+        $this->assertSame('%PDF-1.7 invoice', $this->owner()->appOrders()->invoicePdf('o1'));
+
+        $calls = array_map(fn ($entry) => $entry['request']->getMethod() . ' ' . $entry['request']->getUri()->getPath() . ' ' . $entry['request']->getHeaderLine('Authorization'), $this->sent);
+        $this->assertSame([
+            'GET /api/v1/client/orders/o1/invoice Bearer app-token',
+            'GET /api/v1/client/orders/o1 Bearer app-token',
+            'GET /api/v1/client/orders/o1/invoice Bearer app-token',
+        ], $calls);
+    }
+
+    public function test_an_invoice_that_is_not_ready_is_a_conflict(): void
+    {
+        $this->respond(409, ['message' => 'The invoice document is still being created.', 'error' => 'invoice_not_ready']);
+        $this->respond(200, ['data' => ['id' => 'o1', 'user_id' => 'someone-else']]);
+
+        try {
+            app(AnikeenId::class)->appOrders()->invoicePdf('o1');
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isConflict());
+            $this->assertSame('invoice_not_ready', $e->error);
+        }
+
+        try {
+            $this->owner()->appOrders()->invoicePdf('o1');
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isNotFound());
+            $this->assertSame('order_not_found', $e->error);
+        }
+    }
 }

tests/Id/AppSubscriptionsTest.php

@@ -4,7 +4,10 @@ namespace Anikeen\Id\Tests;
 
 use Anikeen\Id\AnikeenId;
 use Anikeen\Id\Billable;
+use Anikeen\Id\Enums\CancellationReason;
+use Anikeen\Id\Enums\TrialPaymentMethod;
 use Anikeen\Id\Exceptions\ApiException;
+use Anikeen\Id\Resources\AppSubscription;
 use GuzzleHttp\Exception\ConnectException;
 use GuzzleHttp\Psr7\Request;
 use Illuminate\Database\Eloquent\Model;
@@ -87,6 +90,87 @@ class AppSubscriptionsTest extends TestCase
         $this->assertSame(['starts_at' => '2026-05-19T11:33:58+00:00'], $this->sentJson(1));
     }
 
+    public function test_a_checkout_without_arguments_sends_no_body(): void
+    {
+        $this->respond(201, $this->subscription());
+        $this->respond(200, $this->subscription(['active' => true]));
+
+        $this->owner()->appSubscriptions()->create(['name' => 'Server', 'unit' => 'hour', 'price' => 1])->checkout();
+
+        $request = $this->sent[1]['request'];
+        $this->assertSame('PUT /api/v1/client/subscriptions/01JSUB/checkout', $request->getMethod() . ' ' . $request->getUri()->getPath());
+        $this->assertSame('', (string) $request->getBody());
+        $this->assertFalse($request->hasHeader('Content-Type'));
+    }
+
+    public function test_a_checkout_from_a_date_sends_only_the_start(): void
+    {
+        $this->respond(201, $this->subscription());
+        $this->respond(200, $this->subscription(['active' => true]));
+
+        $this->owner()->appSubscriptions()->create(['name' => '.de TLD', 'unit' => 'year', 'price' => '5.19'])
+            ->checkout('2026-05-19T11:33:58+00:00');
+
+        $this->assertSame('{"starts_at":"2026-05-19T11:33:58+00:00"}', (string) $this->sent[1]['request']->getBody());
+    }
+
+    public function test_elapsed_periods_are_billed_up_to_the_ceiling(): void
+    {
+        $this->respond(201, $this->subscription());
+        $this->respond(200, $this->subscription(['active' => true]));
+
+        $this->owner()->appSubscriptions()->create(['name' => '.de TLD', 'unit' => 'year', 'price' => '5.19'])
+            ->checkout(new \DateTimeImmutable('2024-05-19 11:33:58', new \DateTimeZone('UTC')), billElapsedPeriods: true, maxNetAmount: '15.57');
+
+        $request = $this->sent[1]['request'];
+        $this->assertSame('PUT /api/v1/client/subscriptions/01JSUB/checkout', $request->getMethod() . ' ' . $request->getUri()->getPath());
+        $this->assertSame(['starts_at' => '2024-05-19T11:33:58+00:00', 'bill_elapsed_periods' => true, 'max_net_amount' => '15.57'], $this->sentJson(1));
+    }
+
+    public function test_a_float_ceiling_is_sent_with_two_decimals(): void
+    {
+        $this->respond(201, $this->subscription());
+        $this->respond(200, $this->subscription(['active' => true]));
+
+        $this->owner()->appSubscriptions()->create(['name' => '.de TLD', 'unit' => 'year', 'price' => 19.99])
+            ->checkout('2024-05-19', true, 19.99 * 3);
+
+        $this->assertSame(['starts_at' => '2024-05-19', 'bill_elapsed_periods' => true, 'max_net_amount' => 59.97], $this->sentJson(1));
+    }
+
+    public function test_billing_elapsed_periods_needs_a_start_and_a_ceiling(): void
+    {
+        $this->respond(201, $this->subscription());
+        $subscription = $this->owner()->appSubscriptions()->create(['name' => '.de TLD', 'unit' => 'year', 'price' => '5.19']);
+
+        foreach ([[null, '10.00'], ['2024-05-19', null], ['', '10.00'], ['2024-05-19', '']] as [$startsAt, $maxNetAmount]) {
+            try {
+                $subscription->checkout($startsAt, billElapsedPeriods: true, maxNetAmount: $maxNetAmount);
+                $this->fail('Expected an InvalidArgumentException.');
+            } catch (InvalidArgumentException) {
+            }
+        }
+
+        $this->assertCount(1, $this->sent);
+    }
+
+    public function test_an_exceeded_ceiling_carries_the_net_amount(): void
+    {
+        $this->respond(201, $this->subscription());
+        $this->respond(409, ['message' => 'The elapsed periods come to 20.76 net, more than 15.57.', 'error' => 'elapsed_amount_exceeded', 'net_amount' => '20.76']);
+
+        $subscription = $this->owner()->appSubscriptions()->create(['name' => '.de TLD', 'unit' => 'year', 'price' => '5.19']);
+
+        try {
+            $subscription->checkout('2024-05-19', billElapsedPeriods: true, maxNetAmount: '15.57');
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isConflict());
+            $this->assertSame('elapsed_amount_exceeded', $e->error);
+            $this->assertSame('20.76', $e->body()->net_amount);
+        }
+    }
+
     public function test_errors_carry_status_and_error_code(): void
     {
         $this->respond(409, ['message' => 'Product subscription has already been cancelled.', 'error' => 'already_cancelled']);
@@ -174,6 +258,99 @@ class AppSubscriptionsTest extends TestCase
         }
     }
 
+    public function test_a_subscription_starts_with_a_free_trial(): void
+    {
+        $this->respond(201, $this->subscription());
+        $this->respond(200, $this->subscription(['active' => true, 'autorenew' => true, 'status' => 'trial', 'starts_at' => '2026-11-04T10:00:00+00:00', 'trial_ends_at' => date(DATE_ATOM, time() + 14 * 86400)]));
+
+        $subscription = $this->owner()->appSubscriptions()->create(['group' => 'team-1', 'name' => 'Pro', 'unit' => 'month', 'price' => '9.99', 'trial_days' => 14, 'trial_once' => true]);
+        $subscription->checkout();
+
+        $this->assertSame(['group' => 'team-1', 'name' => 'Pro', 'unit' => 'month', 'price' => '9.99', 'trial_days' => 14, 'trial_once' => true, 'user_id' => '01JUSER'], $this->sentJson(0));
+        $this->assertTrue($subscription->isTrial());
+        $this->assertTrue($subscription->isActive());
+    }
+
+    public function test_a_trial_can_be_confirmed_without_a_payment_method_and_end_cancelled(): void
+    {
+        $this->respond(201, $this->subscription(['trial_days' => 14, 'trial_payment_method' => 'optional']));
+        $this->respond(200, $this->subscription(['active' => false, 'cancelled' => true, 'status' => 'cancelled', 'starts_at' => '2026-11-04T10:00:00+00:00', 'trial_ends_at' => '2026-11-18T10:00:00+00:00', 'cancels_at' => '2026-11-18T10:00:00+00:00', 'trial_payment_method' => 'optional', 'cancellation_reason' => 'trial_ended_without_payment_method']));
+
+        $subscription = $this->owner()->appSubscriptions()->create(['name' => 'Pro', 'unit' => 'month', 'price' => '9.99', 'trial_days' => 14, 'trial_payment_method' => TrialPaymentMethod::OPTIONAL]);
+
+        $this->assertSame('optional', $this->sentJson(0)['trial_payment_method']);
+        $this->assertSame(TrialPaymentMethod::OPTIONAL, $subscription->trial_payment_method);
+
+        $ended = $this->owner()->appSubscriptions()->find('01JSUB');
+        $this->assertTrue($ended->isCancelled());
+        $this->assertSame(CancellationReason::TRIAL_ENDED_WITHOUT_PAYMENT_METHOD, $ended->cancellation_reason);
+    }
+
+    public function test_a_used_trial_is_refused_on_checkout(): void
+    {
+        $this->respond(201, $this->subscription());
+        $this->respond(409, ['message' => 'The user already had a free trial.', 'error' => 'trial_already_used']);
+
+        $subscription = $this->owner()->appSubscriptions()->create(['name' => 'Pro', 'unit' => 'month', 'price' => '9.99', 'trial_ends_at' => '2026-12-01T00:00:00+01:00', 'trial_once' => true]);
+
+        try {
+            $subscription->checkout();
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isConflict());
+            $this->assertSame('trial_already_used', $e->error);
+        }
+    }
+
+    public function test_a_subscription_is_created_with_a_discount(): void
+    {
+        $discount = ['label' => 'SUMMER20', 'percent_off' => 20, 'duration' => 'repeating', 'duration_in_periods' => 3];
+        $this->respond(201, $this->subscription(['discount' => [...$discount, 'amount_off' => null, 'periods_remaining' => 3]]));
+
+        $subscription = $this->owner()->appSubscriptions()->create(['name' => 'Pro', 'unit' => 'month', 'price' => '9.99', 'discount' => $discount]);
+
+        $this->assertSame($discount, $this->sentJson(0)['discount']);
+        $this->assertSame('SUMMER20', $subscription->discount->label);
+        $this->assertSame(3, $subscription->discount->periods_remaining);
+    }
+
+    public function test_a_running_subscription_is_changed_now_or_at_the_period_end(): void
+    {
+        $change = ['applies_at' => '2026-12-01T00:00:00+00:00', 'name' => 'Pro', 'description' => null, 'unit' => 'month', 'price' => 14.99, 'discount' => null, 'created_at' => '2026-11-04T10:00:00+00:00'];
+        $this->respond(200, $this->subscription(['active' => true, 'price' => 14.99]));
+        $this->respond(200, $this->subscription(['active' => true, 'price' => 14.99, 'scheduled_change' => $change]));
+        $this->respond(200, $this->subscription(['active' => true, 'price' => 14.99, 'scheduled_change' => null]));
+
+        $subscription = new AppSubscription((object) $this->subscription(['active' => true])['data']);
+
+        $this->assertSame(14.99, $subscription->change(['apply' => AppSubscription::APPLY_NOW, 'price' => '14.99', 'discount' => null])->price);
+        $this->assertSame('2026-12-01T00:00:00+00:00', $subscription->change(['apply' => AppSubscription::APPLY_PERIOD_END, 'unit' => 'month', 'name' => 'Pro'])->scheduled_change->applies_at);
+        $this->assertNull($subscription->cancelScheduledChange()->scheduled_change);
+
+        $this->assertSame([
+            'PUT /api/v1/client/subscriptions/01JSUB/change Bearer app-token',
+            'PUT /api/v1/client/subscriptions/01JSUB/change Bearer app-token',
+            'DELETE /api/v1/client/subscriptions/01JSUB/change Bearer app-token',
+        ], array_map(fn ($entry) => $entry['request']->getMethod() . ' ' . $entry['request']->getUri()->getPath() . ' ' . $entry['request']->getHeaderLine('Authorization'), $this->sent));
+        $this->assertSame(['apply' => 'now', 'price' => '14.99', 'discount' => null], $this->sentJson(0));
+        $this->assertSame(['apply' => 'period_end', 'unit' => 'month', 'name' => 'Pro'], $this->sentJson(1));
+    }
+
+    public function test_a_refused_change_carries_its_error_code(): void
+    {
+        $this->respond(409, ['message' => 'The credit would exceed the open bill.', 'error' => 'credit_exceeds_bill']);
+
+        $subscription = new AppSubscription((object) $this->subscription(['active' => true])['data']);
+
+        try {
+            $subscription->change(['apply' => AppSubscription::APPLY_NOW, 'price' => '1.99']);
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isConflict());
+            $this->assertSame('credit_exceeds_bill', $e->error);
+        }
+    }
+
     public function test_a_missing_user_id_is_reported(): void
     {
         $this->expectException(InvalidArgumentException::class);

tests/Id/BillableModelTest.php

@@ -19,6 +19,8 @@ class BillableModelTest extends TestCase
                 foreach (['addresses', 'countries', 'defaultPaymentMethod', 'invoices', 'orders', 'paymentMethods', 'subscriptions', 'transactions', 'userData'] as $name) {
                     $this->{$name.'Cache'} = 'cached';
                 }
+
+                $this->preferencesCache['global'] = 'cached';
             }
         };
         $user->email = 'ada@example.com';

tests/Id/CheckoutConfirmationTest.php

@@ -2,7 +2,9 @@
 
 namespace Anikeen\Id\Tests;
 
+use Anikeen\Id\AnikeenId;
 use Anikeen\Id\Billable;
+use Anikeen\Id\Exceptions\ApiException;
 use Anikeen\Id\Exceptions\ConfirmationRequiredException;
 use Illuminate\Database\Eloquent\Model;
 
@@ -60,4 +62,44 @@ class CheckoutConfirmationTest extends TestCase
             $this->assertSame('https://id.anikeen.com/checkout/subscriptions/01JSUB', $e->confirmationUrl);
         }
     }
+
+    public function test_a_trusted_app_lets_the_user_confirm_its_order(): void
+    {
+        $this->respond(201, ['data' => ['id' => '01JORD', 'status' => 'draft', 'group' => 'team-1', 'metadata' => ['topup' => '7'], 'expires_at' => '2026-11-05T10:00:00+00:00', 'confirmation_url' => 'https://id.anikeen.com/checkout/orders/01JORD']]);
+
+        $result = app(AnikeenId::class)->createOrderForUser('01JUSER', [
+            'group' => 'team-1',
+            'confirm' => true,
+            'return_url' => 'https://console.test/billing/topup',
+            'metadata' => ['topup' => '7'],
+            'items' => [['type' => 'digital', 'name' => 'Credit', 'unit' => 'onetime', 'units' => 1, 'gross_price' => '10.00']],
+        ]);
+
+        $this->assertSame('POST /api/v1/admin/orders Bearer app-token', $this->sent[0]['request']->getMethod() . ' ' . $this->sent[0]['request']->getUri()->getPath() . ' ' . $this->sent[0]['request']->getHeaderLine('Authorization'));
+        $this->assertTrue($this->sentJson(0)['confirm']);
+        $this->assertSame('https://console.test/billing/topup', $this->sentJson(0)['return_url']);
+        $this->assertSame(['topup' => '7'], $this->sentJson(0)['metadata']);
+        $this->assertSame('01JUSER', $this->sentJson(0)['user_id']);
+        $this->assertSame('https://id.anikeen.com/checkout/orders/01JORD', $result->data->confirmation_url);
+        $this->assertSame('7', $result->data->metadata->topup);
+    }
+
+    public function test_an_expired_confirmation_is_a_conflict(): void
+    {
+        $this->respond(200, ['data' => []]);
+        $this->respond(201, ['data' => ['id' => '01JORD', 'status' => 'draft', 'confirmation_url' => 'https://id.anikeen.com/checkout/orders/01JORD']]);
+        $this->respond(409, ['message' => 'The order was not confirmed in time.', 'error' => 'confirmation_expired']);
+
+        $order = $this->owner()->orders()->create(['confirm' => true, 'return_url' => 'https://shop.test/done', 'metadata' => ['cart' => 1], 'items' => []]);
+
+        $this->assertSame(['confirm' => true, 'return_url' => 'https://shop.test/done', 'metadata' => ['cart' => 1], 'items' => []], $this->sentJson(1));
+
+        try {
+            $order->checkout();
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isConflict());
+            $this->assertSame('confirmation_expired', $e->error);
+        }
+    }
 }

tests/Id/CheckoutSessionsTest.php

@@ -139,6 +139,32 @@ class CheckoutSessionsTest extends TestCase
         $this->assertNull($user->checkoutSessions()->find('unknown'));
     }
 
+    public function test_session_subscriptions_carry_a_free_trial(): void
+    {
+        $this->respond(201, $this->sessionData());
+
+        $this->owner()->appCheckoutSessions()->create(['subscriptions' => [
+            ['group' => 'team-1', 'name' => 'Pro', 'unit' => 'month', 'price' => '9.99', 'trial_days' => 14, 'trial_once' => true],
+            ['group' => 'team-1', 'name' => 'Backup', 'unit' => 'month', 'price' => '1.99', 'trial_ends_at' => '2026-12-01T00:00:00+00:00'],
+        ]]);
+
+        $this->assertSame(14, $this->sentJson(0)['subscriptions'][0]['trial_days']);
+        $this->assertTrue($this->sentJson(0)['subscriptions'][0]['trial_once']);
+        $this->assertSame('2026-12-01T00:00:00+00:00', $this->sentJson(0)['subscriptions'][1]['trial_ends_at']);
+    }
+
+    public function test_session_subscriptions_carry_a_discount(): void
+    {
+        $this->respond(201, $this->sessionData());
+
+        $this->owner()->checkoutSessions()->create(['subscriptions' => [
+            ['name' => 'Pro', 'unit' => 'month', 'price' => 4.99, 'discount' => ['label' => 'WELCOME', 'amount_off' => '1.00', 'duration' => 'once']],
+        ]]);
+
+        $this->assertSame('POST /api/v1/checkout-sessions Bearer user-token', $this->request(0));
+        $this->assertSame(['label' => 'WELCOME', 'amount_off' => '1.00', 'duration' => 'once'], $this->sentJson(0)['subscriptions'][0]['discount']);
+    }
+
     public function test_nothing_is_requested_until_a_method_is_called(): void
     {
         $this->owner()->checkoutSessions();
@@ -159,5 +185,8 @@ class CheckoutSessionsTest extends TestCase
         $this->assertSame(['01JS1', '01JS2'], $event['data']['object']['subscription_ids']);
         $this->assertContains('checkout.expired', EventType::all());
         $this->assertContains('subscription.activated', EventType::all());
+        $this->assertContains('subscription.trial_will_end', EventType::all());
+        $this->assertContains('subscription.discount_ended', EventType::all());
+        $this->assertContains('subscription.updated', EventType::all());
     }
 }

tests/Id/EndpointsTest.php

@@ -4,6 +4,7 @@ namespace Anikeen\Id\Tests;
 
 use Anikeen\Id\AnikeenId;
 use Anikeen\Id\Billable;
+use Anikeen\Id\Exceptions\ApiException;
 use Illuminate\Database\Eloquent\Model;
 
 /**
@@ -54,6 +55,36 @@ class EndpointsTest extends TestCase
         $this->assertSame('GET /api/v1/billing Bearer user-token', $this->sentCall(0));
     }
 
+    public function test_billing_overview_carries_the_billing_limit(): void
+    {
+        $this->respond(200, ['data' => ['current_charges' => 11.9, 'billing_limit' => ['object' => 'billing_limit', 'limit' => '50.00', 'used' => '11.90', 'remaining' => '38.10', 'reached' => false, 'version' => 3]]]);
+
+        $limit = new \Anikeen\Id\Resources\BillingLimit($this->owner()->billingOverview()->billing_limit);
+
+        $this->assertSame('38.10', $limit->remaining());
+        $this->assertTrue($limit->allows('38.10'));
+        $this->assertNull($limit->usedByApp());
+    }
+
+    public function test_charges_and_billing_limits_of_users_use_the_app_token(): void
+    {
+        $charge = ['data' => ['object' => 'charge', 'id' => '01JCHARGE', 'status' => 'open']];
+        $this->respond(201, $charge);
+        $this->respond(200, $charge);
+        $this->respond(200, $charge);
+        $this->respond(200, ['data' => ['object' => 'billing_limit', 'limit' => null]]);
+
+        app(AnikeenId::class)->createChargeForUser('01JUSER', ['idempotency_key' => 'k', 'name' => 'Card', 'quantity' => 1, 'unit_price' => '4.00']);
+        app(AnikeenId::class)->findChargeForUser('01JUSER', '01JCHARGE');
+        app(AnikeenId::class)->voidChargeForUser('01JUSER', '01JCHARGE');
+        app(AnikeenId::class)->billingLimitForUser('01JUSER');
+
+        $this->assertSame('POST /api/v1/client/users/01JUSER/charges Bearer app-token', $this->sentCall(0));
+        $this->assertSame('GET /api/v1/client/users/01JUSER/charges/01JCHARGE Bearer app-token', $this->sentCall(1));
+        $this->assertSame('POST /api/v1/client/users/01JUSER/charges/01JCHARGE/void Bearer app-token', $this->sentCall(2));
+        $this->assertSame('GET /api/v1/client/users/01JUSER/billing-limit Bearer app-token', $this->sentCall(3));
+    }
+
     public function test_invoice_download_url_is_read_not_updated(): void
     {
         $this->respond(200, $this->list([['id' => 'inv1']]));
@@ -90,6 +121,52 @@ class EndpointsTest extends TestCase
         $this->assertSame(['email' => 'erika@example.com', 'password' => 'secret-123', 'name' => 'Erika Mustermann', 'password_confirmation' => 'secret-123'], $this->sentJson(0));
     }
 
+    public function test_create_user_can_send_an_invitation(): void
+    {
+        $this->respond(201, ['data' => ['id' => '01JNEW', 'email' => 'erika@example.com', 'created' => true, 'invitation_sent' => true]]);
+
+        $result = app(AnikeenId::class)->createUser(['name' => 'Erika Mustermann', 'email' => 'erika@example.com', 'send_invitation' => true]);
+
+        $this->assertSame('POST /api/v1/admin/users Bearer app-token', $this->sentCall(0));
+        $this->assertSame(['name' => 'Erika Mustermann', 'email' => 'erika@example.com', 'send_invitation' => true], $this->sentJson(0));
+        $this->assertTrue($result->data->created);
+        $this->assertTrue($result->data->invitation_sent);
+    }
+
+    public function test_find_user_by_email_uses_the_lookup_endpoint(): void
+    {
+        $this->respond(200, ['data' => ['id' => '01JUSER', 'name' => 'Erika', 'email' => 'erika@example.com', 'email_verified' => true, 'has_billing_address' => false]]);
+
+        $result = app(AnikeenId::class)->findUserByEmail('Erika@Example.com');
+
+        $this->assertSame('POST /api/v1/admin/users/lookup Bearer app-token', $this->sentCall(0));
+        $this->assertSame(['email' => 'Erika@Example.com'], $this->sentJson(0));
+        $this->assertSame('01JUSER', $result->data->id);
+        $this->assertFalse($result->data->has_billing_address);
+    }
+
+    public function test_find_user_by_email_returns_null_without_an_account(): void
+    {
+        $this->respond(404, ['message' => 'User not found.', 'error' => 'user_not_found']);
+
+        $this->assertNull(app(AnikeenId::class)->findUserByEmail('nobody@example.com'));
+    }
+
+    public function test_find_user_by_email_throws_other_failures(): void
+    {
+        $this->respond(404, ['message' => 'Not found.']); // e.g. an Anikeen ID without the lookup
+        $this->respond(500, ['message' => 'Server Error']);
+
+        foreach ([404, 500] as $status) {
+            try {
+                app(AnikeenId::class)->findUserByEmail('erika@example.com');
+                $this->fail('Expected an ApiException.');
+            } catch (ApiException $e) {
+                $this->assertSame($status, $e->status);
+            }
+        }
+    }
+
     public function test_email_check_and_socialite_users(): void
     {
         $this->respond(200, ['data' => ['exists' => true]]);
@@ -199,6 +276,35 @@ class EndpointsTest extends TestCase
         $this->assertSame('POST /api/v1/admin/transactions Bearer app-token', $this->sentCall(1));
     }
 
+    public function test_billing_portal_links_for_users_use_the_app_token(): void
+    {
+        $link = ['object' => 'billing_portal_link', 'url' => 'https://id.test/billing/portal/01JUSER?signature=x', 'user_id' => '01JUSER', 'flow' => 'invoices', 'group' => 'team-1', 'return_url' => 'https://console.test/billing', 'expires_at' => '2026-11-04T10:15:00+00:00'];
+        $this->respond(201, ['data' => $link]);
+        $this->respond(201, ['data' => $link]);
+
+        $created = app(AnikeenId::class)->createBillingPortalLinkForUser('01JUSER', ['return_url' => 'https://console.test/billing', 'group' => 'team-1', 'flow' => 'invoices']);
+        $url = $this->owner()->appBillingPortalUrl(['flow' => 'payment_method_update']);
+
+        $this->assertSame('billing_portal_link', $created->object);
+        $this->assertSame($link['url'], $url);
+        $this->assertSame('POST /api/v1/client/users/01JUSER/billing-portal Bearer app-token', $this->sentCall(0));
+        $this->assertSame(['return_url' => 'https://console.test/billing', 'group' => 'team-1', 'flow' => 'invoices'], $this->sentJson(0));
+        $this->assertSame('POST /api/v1/client/users/01JUSER/billing-portal Bearer app-token', $this->sentCall(1));
+        $this->assertSame(['flow' => 'payment_method_update'], $this->sentJson(1));
+    }
+
+    public function test_a_refused_billing_portal_link_is_an_api_exception(): void
+    {
+        $this->respond(422, ['message' => 'The return URL has to point to one of the app\'s redirect URIs.', 'errors' => ['return_url' => ['…']]]);
+
+        try {
+            $this->owner()->appBillingPortalUrl(['return_url' => 'https://elsewhere.test']);
+            $this->fail('Expected an ApiException.');
+        } catch (ApiException $e) {
+            $this->assertSame(422, $e->status);
+        }
+    }
+
     public function test_order_preview_maps_the_country_into_the_billing_address(): void
     {
         $this->respond(200, ['data' => ['gross_total' => 11.9]]);
@@ -207,4 +313,133 @@ class EndpointsTest extends TestCase
 
         $this->assertSame(['items' => [], 'billing_address' => ['country_iso' => 'DE']], $this->sentJson(0));
     }
+
+    private function preference(string $namespace, string $key, mixed $value, int $version = 7): array
+    {
+        return ['namespace' => $namespace, 'key' => $key, 'value' => $value, 'version' => $version, 'updated_at' => '2026-11-06T10:00:00.000000Z', 'updated_by' => ['type' => 'app', 'client_id' => 'app-client']];
+    }
+
+    private function conditions(int $index): array
+    {
+        $request = $this->sent[$index]['request'];
+
+        return [$request->getHeaderLine('If-Match'), $request->getHeaderLine('If-None-Match')];
+    }
+
+    public function test_global_preferences_of_the_user(): void
+    {
+        $this->respond(200, ['data' => [$this->preference('global', 'appearance', 'dark')]]);
+
+        $preferences = $this->owner()->globalPreferences();
+
+        $this->assertSame('dark', $preferences->get('appearance'));
+        $this->assertSame('GET /api/v1/preferences/global Bearer user-token', $this->sentCall(0));
+    }
+
+    public function test_global_preference_with_a_default(): void
+    {
+        $this->respond(200, ['data' => [$this->preference('global', 'appearance', 'light')]]);
+
+        $owner = $this->owner();
+
+        $this->assertSame('light', $owner->globalPreference('appearance'));
+        $this->assertSame('system', $owner->globalPreference('unknown', 'system'));
+        $this->assertCount(1, $this->sent);
+        $this->assertSame('GET /api/v1/preferences/global Bearer user-token', $this->sentCall(0));
+    }
+
+    public function test_set_global_preference(): void
+    {
+        $this->respond(201, ['data' => $this->preference('global', 'appearance', 'dark', 8)]);
+        $this->respond(200, ['data' => $this->preference('global', 'appearance', 'light', 9)]);
+
+        $created = $this->owner()->setGlobalPreference('appearance', 'dark');
+        $updated = $this->owner()->setGlobalPreference('appearance', 'light', ifVersion: 8);
+
+        $this->assertTrue($created->wasCreated());
+        $this->assertFalse($updated->wasCreated());
+        $this->assertSame(9, $updated->version);
+        $this->assertSame('PUT /api/v1/preferences/global/appearance Bearer user-token', $this->sentCall(0));
+        $this->assertSame(['value' => 'dark'], $this->sentJson(0));
+        $this->assertSame(['', ''], $this->conditions(0));
+        $this->assertSame(['"8"', ''], $this->conditions(1));
+    }
+
+    public function test_delete_global_preference(): void
+    {
+        $this->respond(204);
+        $this->respond(204);
+
+        $this->owner()->deleteGlobalPreference('appearance');
+        $this->owner()->deleteGlobalPreference('appearance', ifVersion: 9);
+
+        $this->assertSame('DELETE /api/v1/preferences/global/appearance Bearer user-token', $this->sentCall(0));
+        $this->assertSame('', (string) $this->sent[0]['request']->getBody());
+        $this->assertSame(['', ''], $this->conditions(0));
+        $this->assertSame(['"9"', ''], $this->conditions(1));
+    }
+
+    public function test_preferences_by_user_id(): void
+    {
+        $this->respond(200, ['data' => [$this->preference('acme', 'plan', 'pro'), $this->preference('acme', 'theme', ['accent' => 'blue'])]]);
+
+        $preferences = app(AnikeenId::class)->preferencesByUserId('01JUSER', 'acme');
+
+        $this->assertEquals(['plan' => 'pro', 'theme' => (object) ['accent' => 'blue']], $preferences->values());
+        $this->assertSame('blue', $preferences->find('theme')->value->accent);
+        $this->assertNull($preferences->find('missing'));
+        $this->assertSame('GET /api/v1/client/users/01JUSER/preferences/acme Bearer app-token', $this->sentCall(0));
+    }
+
+    public function test_preference_by_user_id(): void
+    {
+        $this->respond(200, ['data' => $this->preference('acme', 'plan', 'pro')]);
+
+        $preference = app(AnikeenId::class)->preferenceByUserId('01JUSER', 'acme', 'plan');
+
+        $this->assertSame('pro', $preference->value);
+        $this->assertSame(7, $preference->version);
+        $this->assertSame('GET /api/v1/client/users/01JUSER/preferences/acme/plan Bearer app-token', $this->sentCall(0));
+    }
+
+    public function test_set_preference_by_user_id(): void
+    {
+        $this->respond(200, ['data' => $this->preference('acme', 'plan', 'pro')]);
+        $this->respond(200, ['data' => $this->preference('acme', 'plan', 'pro')]);
+        $this->respond(201, ['data' => $this->preference('acme', 'plan', 'pro')]);
+
+        $anikeenId = app(AnikeenId::class);
+        $anikeenId->setPreferenceByUserId('01JUSER', 'acme', 'plan', 'pro');
+        $anikeenId->setPreferenceByUserId('01JUSER', 'acme', 'plan', 'pro', ifVersion: 7);
+        $anikeenId->setPreferenceByUserId('01JUSER', 'acme', 'plan', 'pro', createOnly: true);
+
+        $this->assertSame('PUT /api/v1/client/users/01JUSER/preferences/acme/plan Bearer app-token', $this->sentCall(0));
+        $this->assertSame(['value' => 'pro'], $this->sentJson(0));
+        $this->assertSame(['', ''], $this->conditions(0));
+        $this->assertSame(['"7"', ''], $this->conditions(1));
+        $this->assertSame(['', '*'], $this->conditions(2));
+    }
+
+    public function test_delete_preference_by_user_id(): void
+    {
+        $this->respond(204);
+        $this->respond(204);
+
+        app(AnikeenId::class)->deletePreferenceByUserId('01JUSER', 'acme', 'plan');
+        app(AnikeenId::class)->deletePreferenceByUserId('01JUSER', 'acme', 'plan', ifVersion: 7);
+
+        $this->assertSame('DELETE /api/v1/client/users/01JUSER/preferences/acme/plan Bearer app-token', $this->sentCall(0));
+        $this->assertSame(['', ''], $this->conditions(0));
+        $this->assertSame(['"7"', ''], $this->conditions(1));
+    }
+
+    public function test_find_user_id_by_preference(): void
+    {
+        $this->respond(200, ['data' => ['user_id' => '01JUSER', 'namespace' => 'acme', 'key' => 'customer_id', 'version' => 7, 'updated_at' => '2026-11-06T10:00:00.000000Z']]);
+
+        $this->assertSame('01JUSER', app(AnikeenId::class)->findUserIdByPreference('acme', 'customer_id', 'cus_123'));
+        $this->assertSame('POST /api/v1/client/preferences/acme/lookup Bearer app-token', $this->sentCall(0));
+        $this->assertSame(['key' => 'customer_id', 'value' => 'cus_123'], $this->sentJson(0));
+        $this->assertSame('', $this->sent[0]['request']->getUri()->getQuery());
+    }
 }

tests/Id/PreferencesTest.php

@@ -0,0 +1,226 @@
+<?php
+
+namespace Anikeen\Id\Tests;
+
+use Anikeen\Id\AnikeenId;
+use Anikeen\Id\Billable;
+use Anikeen\Id\Enums\Appearance;
+use Anikeen\Id\Enums\SharedPreference;
+use Anikeen\Id\Exceptions\ApiException;
+use Anikeen\Id\Exceptions\PreconditionFailedException;
+use Illuminate\Database\Eloquent\Model;
+use InvalidArgumentException;
+
+class PreferencesTest extends TestCase
+{
+    private function owner(): Model
+    {
+        $owner = new class extends Model {
+            use Billable;
+
+            protected $guarded = [];
+        };
+        $owner->anikeen_id = '01JUSER';
+        $owner->anikeen_id_access_token = 'user-token';
+
+        return $owner;
+    }
+
+    private function preference(string $key, mixed $value, int $version = 7): array
+    {
+        return ['data' => ['namespace' => 'global', 'key' => $key, 'value' => $value, 'version' => $version, 'updated_at' => '2026-11-06T10:00:00.000000Z', 'updated_by' => ['type' => 'user', 'client_id' => 'app-client']]];
+    }
+
+    private function path(int $index): string
+    {
+        return $this->sent[$index]['request']->getUri()->getPath();
+    }
+
+    public function test_the_lookup_returns_null_when_nobody_holds_the_value(): void
+    {
+        $this->respond(404, ['message' => 'The preference is not set.', 'error' => 'preference_not_found']);
+
+        $this->assertNull(app(AnikeenId::class)->findUserIdByPreference('acme', 'customer_id', 'cus_123'));
+    }
+
+    public function test_the_lookup_throws_on_other_not_found_answers(): void
+    {
+        $this->respond(404, ['message' => 'The namespace does not exist.', 'error' => 'namespace_not_found']);
+
+        try {
+            app(AnikeenId::class)->findUserIdByPreference('acme', 'customer_id', 'cus_123');
+            $this->fail('no exception');
+        } catch (ApiException $e) {
+            $this->assertSame(404, $e->status);
+            $this->assertSame('namespace_not_found', $e->error);
+        }
+    }
+
+    public function test_the_lookup_throws_on_a_404_without_an_error_code(): void
+    {
+        $this->respond(404, ['message' => 'Not Found']);
+
+        $this->expectException(ApiException::class);
+
+        app(AnikeenId::class)->findUserIdByPreference('acme', 'customer_id', 'cus_123');
+    }
+
+    public function test_the_lookup_throws_on_validation_errors(): void
+    {
+        $this->respond(422, ['message' => 'The key is not unique.', 'error' => 'key_not_unique']);
+
+        try {
+            app(AnikeenId::class)->findUserIdByPreference('acme', 'plan', 'pro');
+            $this->fail('no exception');
+        } catch (ApiException $e) {
+            $this->assertSame('key_not_unique', $e->error);
+        }
+    }
+
+    public function test_a_failed_app_write_carries_the_current_version(): void
+    {
+        $this->respond(412, ['message' => 'The preference has another version.', 'error' => 'preference_version_mismatch', 'current_version' => 12]);
+
+        try {
+            app(AnikeenId::class)->setPreferenceByUserId('01JUSER', 'acme', 'plan', 'pro', ifVersion: 7);
+            $this->fail('no exception');
+        } catch (PreconditionFailedException $e) {
+            $this->assertSame(412, $e->status);
+            $this->assertSame('preference_version_mismatch', $e->error);
+            $this->assertSame(12, $e->currentVersion());
+        }
+    }
+
+    public function test_a_create_only_write_of_a_set_key_fails(): void
+    {
+        $this->respond(412, ['message' => 'The preference is already set.', 'error' => 'preference_exists', 'current_version' => 3]);
+
+        try {
+            app(AnikeenId::class)->setPreferenceByUserId('01JUSER', 'acme', 'plan', 'pro', createOnly: true);
+            $this->fail('no exception');
+        } catch (PreconditionFailedException $e) {
+            $this->assertSame('preference_exists', $e->error);
+            $this->assertSame(3, $e->currentVersion());
+        }
+    }
+
+    public function test_a_failed_user_write_carries_the_current_version(): void
+    {
+        $this->respond(412, ['message' => 'The preference has another version.', 'error' => 'preference_version_mismatch', 'current_version' => null]);
+        $this->respond(412, ['message' => 'The preference has another version.', 'error' => 'preference_version_mismatch', 'current_version' => 5]);
+
+        foreach ([
+            fn () => $this->owner()->setGlobalPreference('appearance', 'dark', ifVersion: 4),
+            fn () => $this->owner()->deleteGlobalPreference('appearance', ifVersion: 4),
+        ] as $i => $call) {
+            try {
+                $call();
+                $this->fail('no exception');
+            } catch (PreconditionFailedException $e) {
+                $this->assertSame([null, 5][$i], $e->currentVersion());
+            }
+        }
+    }
+
+    public function test_a_write_is_either_conditional_or_create_only(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        try {
+            app(AnikeenId::class)->setPreferenceByUserId('01JUSER', 'acme', 'plan', 'pro', ifVersion: 7, createOnly: true);
+        } finally {
+            $this->assertCount(0, $this->sent);
+        }
+    }
+
+    public function test_writes_clear_the_cached_preferences(): void
+    {
+        $owner = $this->owner();
+
+        $this->respond(200, ['data' => [$this->preference('appearance', 'light')['data']]]);
+        $this->respond(200, $this->preference('appearance', 'dark', 8));
+        $this->respond(200, ['data' => [$this->preference('appearance', 'dark', 8)['data']]]);
+        $this->respond(204);
+        $this->respond(200, ['data' => []]);
+
+        $this->assertSame('light', $owner->globalPreference(SharedPreference::APPEARANCE));
+        $this->assertSame('light', $owner->globalPreference(SharedPreference::APPEARANCE)); // cached
+        $owner->setGlobalPreference(SharedPreference::APPEARANCE, Appearance::DARK);
+        $this->assertSame('dark', $owner->globalPreference(SharedPreference::APPEARANCE));
+        $owner->deleteGlobalPreference(SharedPreference::APPEARANCE);
+        $this->assertSame(Appearance::SYSTEM, $owner->globalPreference(SharedPreference::APPEARANCE, Appearance::SYSTEM));
+
+        $this->assertCount(5, $this->sent);
+        $this->assertSame(['GET', 'PUT', 'GET', 'DELETE', 'GET'], array_map(fn ($sent) => $sent['request']->getMethod(), $this->sent));
+    }
+
+    public function test_a_failed_write_clears_the_cached_preferences_too(): void
+    {
+        $owner = $this->owner();
+
+        $this->respond(200, ['data' => [$this->preference('appearance', 'light')['data']]]);
+        $this->respond(412, ['message' => 'x', 'error' => 'preference_version_mismatch', 'current_version' => 9]);
+        $this->respond(200, ['data' => [$this->preference('appearance', 'dark', 9)['data']]]);
+
+        $owner->globalPreferences();
+
+        try {
+            $owner->setGlobalPreference('appearance', 'dark', ifVersion: 7);
+        } catch (PreconditionFailedException) {
+        }
+
+        $this->assertSame('dark', $owner->globalPreference('appearance'));
+        $this->assertCount(3, $this->sent);
+    }
+
+    public function test_path_segments_are_encoded(): void
+    {
+        $this->respond(200, ['data' => []]);
+        $this->respond(204);
+        $this->respond(200, ['data' => ['user_id' => '01JUSER']]);
+
+        $anikeenId = app(AnikeenId::class);
+        $anikeenId->preferencesByUserId('a/b', 'x y');
+        $anikeenId->deletePreferenceByUserId('01JUSER', 'acme', '../key?');
+        $anikeenId->findUserIdByPreference('ac/me', 'k', 'v');
+
+        $this->assertSame('/api/v1/client/users/a%2Fb/preferences/x%20y', $this->path(0));
+        $this->assertSame('/api/v1/client/users/01JUSER/preferences/acme/..%2Fkey%3F', $this->path(1));
+        $this->assertSame('/api/v1/client/preferences/ac%2Fme/lookup', $this->path(2));
+    }
+
+    public function test_values_round_trip_as_json(): void
+    {
+        $this->respond(201, $this->preference('settings', (object) []));
+
+        $preference = app(AnikeenId::class)->setPreferenceByUserId('01JUSER', 'acme', 'settings', (object) []);
+
+        $this->assertSame('{"value":{}}', (string) $this->sent[0]['request']->getBody());
+        $this->assertEquals((object) [], $preference->value);
+    }
+
+    public function test_a_deleted_user_is_not_found(): void
+    {
+        $this->respond(404, ['message' => 'The user does not exist.', 'error' => 'user_not_found']);
+
+        try {
+            app(AnikeenId::class)->preferenceByUserId('01JGONE', 'acme', 'plan');
+            $this->fail('no exception');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isNotFound());
+            $this->assertSame('user_not_found', $e->error);
+        }
+    }
+
+    public function test_an_unreachable_service_is_temporary(): void
+    {
+        $this->http->append(new \GuzzleHttp\Exception\ConnectException('down', new \GuzzleHttp\Psr7\Request('DELETE', 'x')));
+
+        try {
+            $this->owner()->deleteGlobalPreference('appearance');
+            $this->fail('no exception');
+        } catch (ApiException $e) {
+            $this->assertTrue($e->isTemporary());
+        }
+    }
+}

tests/Id/RequestHeadersTest.php

@@ -0,0 +1,113 @@
+<?php
+
+namespace Anikeen\Id\Tests;
+
+use Anikeen\Id\AnikeenId;
+use Anikeen\Id\Exceptions\ApiException;
+use Anikeen\Id\Exceptions\CollectionException;
+use Anikeen\Id\Exceptions\PreconditionFailedException;
+use Anikeen\Id\Resources\SshKeys;
+use Anikeen\Id\Support\AppRequest;
+
+class RequestHeadersTest extends TestCase
+{
+    public function test_requests_without_extra_headers_send_the_same_headers_as_before(): void
+    {
+        $this->respond(200, ['data' => []]);
+
+        AppRequest::send('GET', 'v1/client/subscriptions', null, ['page' => 1]);
+
+        $request = $this->sent[0]['request'];
+        $this->assertSame(['Bearer app-token'], $request->getHeader('Authorization'));
+        $this->assertSame(['app-client'], $request->getHeader('Client-ID'));
+        $this->assertFalse($request->hasHeader('If-Match'));
+        $this->assertFalse($request->hasHeader('If-None-Match'));
+        $this->assertSame('page=1', $request->getUri()->getQuery());
+    }
+
+    public function test_app_requests_send_extra_headers_also_on_the_retry_with_a_fresh_token(): void
+    {
+        $this->respond(401, ['message' => 'Unauthenticated.']);
+        $this->respond(200, ['data' => []]);
+
+        AppRequest::send('PUT', 'v1/x', ['value' => 1], [], ['If-Match' => '"7"']);
+
+        $this->assertSame('"7"', $this->sent[0]['request']->getHeaderLine('If-Match'));
+        $this->assertSame('"7"', $this->sent[1]['request']->getHeaderLine('If-Match'));
+        $this->assertSame('Bearer fresh-app-token', $this->sent[1]['request']->getHeaderLine('Authorization'));
+    }
+
+    public function test_extra_headers_do_not_replace_the_client_and_token_headers(): void
+    {
+        $this->respond(200, ['data' => []]);
+
+        app(AnikeenId::class)->withToken('user-token')
+            ->put('v1/x', ['value' => 1], [], null, ['If-None-Match' => '*', 'Authorization' => 'Bearer other']);
+
+        $request = $this->sent[0]['request'];
+        $this->assertSame('*', $request->getHeaderLine('If-None-Match'));
+        $this->assertSame('Bearer user-token', $request->getHeaderLine('Authorization'));
+    }
+
+    public function test_get_and_delete_helpers_take_headers(): void
+    {
+        $this->respond(200, ['data' => []]);
+        $this->respond(204);
+
+        $anikeenId = app(AnikeenId::class)->withToken('user-token');
+        $anikeenId->get('v1/x', [], null, ['If-None-Match' => '"3"']);
+        $anikeenId->delete('v1/x', [], [], null, ['If-Match' => '"3"']);
+
+        $this->assertSame('"3"', $this->sent[0]['request']->getHeaderLine('If-None-Match'));
+        $this->assertSame('"3"', $this->sent[1]['request']->getHeaderLine('If-Match'));
+    }
+
+    public function test_a_412_of_an_app_request_is_a_precondition_failed_exception(): void
+    {
+        $this->respond(412, ['message' => 'The preference has another version.', 'error' => 'preference_version_mismatch', 'current_version' => 12]);
+
+        try {
+            AppRequest::send('PUT', 'v1/x', ['value' => 1], [], ['If-Match' => '"7"']);
+            $this->fail('no exception');
+        } catch (PreconditionFailedException $e) {
+            $this->assertSame(412, $e->status);
+            $this->assertSame('preference_version_mismatch', $e->error);
+            $this->assertSame(12, $e->currentVersion());
+        }
+    }
+
+    public function test_a_412_of_a_user_request_is_a_precondition_failed_exception(): void
+    {
+        $this->respond(412, ['message' => 'The preference is already set.', 'error' => 'preference_exists', 'current_version' => null]);
+
+        $result = app(AnikeenId::class)->withToken('user-token')->put('v1/x', ['value' => 1]);
+        $e = ApiException::fromResult($result);
+
+        $this->assertInstanceOf(PreconditionFailedException::class, $e);
+        $this->assertSame('preference_exists', $e->error);
+        $this->assertNull($e->currentVersion());
+    }
+
+    public function test_list_errors_keep_their_collection_exception_type(): void
+    {
+        $this->respond(412, ['message' => 'x', 'error' => 'x']);
+
+        $this->expectException(CollectionException::class);
+
+        $anikeenId = app(AnikeenId::class)->withToken('user-token');
+        SshKeys::builder(fn () => $anikeenId->get('v1/ssh-keys'));
+    }
+
+    public function test_other_errors_stay_plain_api_exceptions(): void
+    {
+        $this->respond(409, ['message' => 'Taken.', 'error' => 'preference_value_taken']);
+
+        try {
+            AppRequest::send('PUT', 'v1/x', ['value' => 1]);
+            $this->fail('no exception');
+        } catch (ApiException $e) {
+            $this->assertSame(ApiException::class, $e::class);
+            $this->assertTrue($e->isConflict());
+        }
+    }
+}

tests/Id/ScopeTest.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace Anikeen\Id\Tests;
+
+use Anikeen\Id\Enums\Scope;
+use PHPUnit\Framework\Attributes\DataProvider;
+use ReflectionClass;
+
+class ScopeTest extends TestCase
+{
+    public static function newScopes(): array
+    {
+        return [
+            'products:read' => [Scope::PRODUCTS_READ, 'products:read'],
+            'reseller-customers' => [Scope::RESELLER_CUSTOMERS, 'reseller-customers'],
+            'reseller-customers:read' => [Scope::RESELLER_CUSTOMERS_READ, 'reseller-customers:read'],
+            'reseller-grants' => [Scope::RESELLER_GRANTS, 'reseller-grants'],
+            'reseller-orders' => [Scope::RESELLER_ORDERS, 'reseller-orders'],
+        ];
+    }
+
+    #[DataProvider('newScopes')]
+    public function test_the_product_and_reseller_scopes_have_their_names(string $constant, string $expected): void
+    {
+        $this->assertSame($expected, $constant);
+    }
+
+    public function test_the_preference_scopes_match_anikeen_id(): void
+    {
+        $this->assertSame('preferences', Scope::PREFERENCES);
+        $this->assertSame('preferences:read', Scope::PREFERENCES_READ);
+        $this->assertSame('preferences:client', Scope::PREFERENCES_CLIENT);
+    }
+
+    public function test_there_is_no_full_products_scope_the_console_would_not_accept(): void
+    {
+        // the Console's product APIs accept `user`, `user:read` and `products:read` only
+        $this->assertNotContains('products', (new ReflectionClass(Scope::class))->getConstants());
+    }
+
+    public function test_every_scope_follows_the_resource_and_level_schema(): void
+    {
+        $scopes = array_values((new ReflectionClass(Scope::class))->getConstants());
+
+        $this->assertSame($scopes, array_values(array_unique($scopes)), 'scope values must be unique');
+
+        foreach ($scopes as $scope) {
+            // "resource" (full access), "resource:read" or "resource:client"; Anikeen ID groups by resource
+            $this->assertMatchesRegularExpression('/^[a-z]+(-[a-z]+)*(:(read|client))?$/', $scope);
+        }
+    }
+
+    public function test_each_reseller_resource_is_its_own_group(): void
+    {
+        $groups = collect((new ReflectionClass(Scope::class))->getConstants())
+            ->filter(fn (string $scope) => str_starts_with($scope, 'reseller-'))
+            ->groupBy(fn (string $scope) => explode(':', $scope)[0])
+            ->map(fn ($scopes) => $scopes->sort()->values()->all())
+            ->all();
+
+        $this->assertSame([
+            'reseller-customers' => ['reseller-customers', 'reseller-customers:read'],
+            'reseller-grants' => ['reseller-grants'],
+            'reseller-orders' => ['reseller-orders'],
+        ], $groups);
+    }
+}

tests/Id/SharedPreferenceTest.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Anikeen\Id\Tests;
+
+use Anikeen\Id\Enums\Appearance;
+use Anikeen\Id\Enums\SharedPreference;
+
+class SharedPreferenceTest extends TestCase
+{
+    public function test_the_shared_keys_and_values_match_anikeen_id(): void
+    {
+        $this->assertSame('global', SharedPreference::NAMESPACE);
+        $this->assertSame('appearance', SharedPreference::APPEARANCE);
+        $this->assertSame(['system', 'light', 'dark'], Appearance::all());
+    }
+}

tests/Id/SubscriptionStatusTest.php

@@ -47,6 +47,7 @@ class SubscriptionStatusTest extends TestCase
             $this->assertSame($status, $resource->status());
             $this->assertSame($running, $resource->isActive());
             $this->assertSame($status === SubscriptionStatus::DRAFT, $resource->isDraft());
+            $this->assertSame($status === SubscriptionStatus::TRIAL, $resource->isTrial());
             $this->assertSame($status === SubscriptionStatus::PAUSED, $resource->isPaused());
             $this->assertSame($status === SubscriptionStatus::CANCELLING, $resource->isCancelling());
             $this->assertSame($status === SubscriptionStatus::EXPIRED, $resource->isExpired());

tests/Id/WebhookTest.php

@@ -3,6 +3,7 @@
 namespace Anikeen\Id\Tests;
 
 use Anikeen\Id\Exceptions\SignatureVerificationException;
+use Anikeen\Id\Webhooks\EventType;
 use Anikeen\Id\Webhooks\Webhook;
 
 class WebhookTest extends TestCase
@@ -53,4 +54,45 @@ class WebhookTest extends TestCase
 
         Webhook::constructEvent($this->payload, null, $this->secret);
     }
+
+    public function test_a_renewal_carries_the_booked_period(): void
+    {
+        $this->payload = json_encode(['id' => '01JEVT', 'type' => EventType::SUBSCRIPTION_RENEWED, 'created' => time(), 'data' => [
+            'object' => ['id' => '01JSUB', 'status' => 'active'],
+            'period' => ['object' => 'subscription_period', 'subscription_id' => '01JSUB', 'period_start' => '2026-11-01T00:00:00+00:00', 'period_end' => '2026-12-01T00:00:00+00:00', 'periods' => 1, 'first_period' => true, 'unit' => 'month', 'order_id' => '01JORD', 'order_item_id' => '01JITEM', 'items' => [], 'currency_iso' => 'EUR', 'net_amount' => 8],
+        ]]);
+
+        $event = Webhook::constructEvent($this->payload, $this->header(), $this->secret);
+
+        $this->assertSame('subscription.renewed', $event['type']);
+        $this->assertSame('01JORD', $event['data']['period']['order_id']);
+        $this->assertTrue($event['data']['period']['first_period']);
+        $this->assertContains(EventType::SUBSCRIPTION_RENEWED, EventType::all());
+    }
+
+    public function test_refunds_have_their_own_event_type(): void
+    {
+        $this->assertSame('order.refunded', EventType::ORDER_REFUNDED);
+        $this->assertContains(EventType::ORDER_REFUNDED, EventType::all());
+    }
+
+    public function test_billing_limit_events_have_their_own_types(): void
+    {
+        $this->assertSame('billing_limit.reached', EventType::BILLING_LIMIT_REACHED);
+        $this->assertSame('billing_limit.available', EventType::BILLING_LIMIT_AVAILABLE);
+        $this->assertContains(EventType::BILLING_LIMIT_REACHED, EventType::all());
+        $this->assertContains(EventType::BILLING_LIMIT_AVAILABLE, EventType::all());
+    }
+
+    public function test_a_change_carries_the_previous_attributes(): void
+    {
+        $this->payload = json_encode(['id' => '01JEVT', 'type' => EventType::SUBSCRIPTION_UPDATED, 'created' => time(), 'data' => [
+            'object' => ['id' => '01JSUB', 'price' => 14.99],
+            'previous_attributes' => ['price' => 9.99],
+        ]]);
+
+        $event = Webhook::constructEvent($this->payload, $this->header(), $this->secret);
+
+        $this->assertSame(9.99, $event['data']['previous_attributes']['price']);
+    }
 }