unsupervised-scheduler/docs/features/parent-guardian-accounts.md

# Feature: Parent/Guardian Accounts

## Overview
A parent or guardian registers **once** and manages lessons for **one or more
children**, without each child needing their own login. The guardian signs in,
picks which child a booking is for, and pays for all of them from one account.

A guardian may also be a student in their own right — they appear in their own
"who is this for?" selector alongside their children, so a parent taking lessons
next to their kids needs only the one account.

## Vocabulary: "child" in the code, "student" in the UI

The interface says **student** and **profile**; the code says **child** and
**family**. This is deliberate, not drift. Every identifier below — the
`us_guardian_links` columns, `GuardianService::createChild()`, the `children[]`
request parameters, the `child_name` form fields, the `us-scheduler/family`
block name and the `[us_family]` shortcode — is a stable contract with the
database, saved post content and existing installs, so renaming them would break
sites for no user-visible gain. Only the strings a person reads were changed.

When adding to this feature, keep the split: internal names follow the
data model, translatable strings follow the interface.

## Core Decision: children are accountless WordPress users

Every `student_id` column in `src/Schema.php` (`us_lessons`, `us_payments`,
`us_credits`, `us_group_enrollments`, `us_question_answers`,
`us_policy_acceptances`, `us_group_access`) is a `wp_users` id, and booking,
billing, credits, policies and registration answers all resolve it directly.

Rather than change what `student_id` means, **a child is a real `wp_users` row**
with the `us_student` role, created without a usable login:

- no password (`wp_generate_password()` is used and discarded — nothing is ever
  emailed, so it cannot be guessed into a session),
- no real email address; a child gets a placeholder login on the RFC 2606
  reserved `.invalid` TLD (`us-child-<random>@child.invalid`, see
  `GuardianService::childEmail()`) — a well-formed address that can never
  resolve, so nothing about a child's account can be emailed somewhere real,
- the `us_child` user meta flag set to `1`, which
  `Guardian\ChildLoginGate` uses to block authentication outright.

Consequences:

- `us_lessons`, `us_group_enrollments`, `us_question_answers` and
  `us_group_access` are **unchanged** — a child books like any other student.
- A child can be promoted to their own login later by setting a password and a
  real email and clearing `us_child`; no data migrates.
- A `us_guardians` link table maps guardian → child.

The alternative — a standalone `us_students` table decoupled from `wp_users` —
was rejected for v1: it changes the meaning of `student_id` on seven tables and
requires migrating every existing row.

## Data Model — `{prefix}us_guardians`

| Column         | Type            | Notes                                                     |
|----------------|-----------------|-----------------------------------------------------------|
| `id`           | BIGINT UNSIGNED | Primary key                                               |
| `guardian_id`  | BIGINT UNSIGNED | WordPress user ID of the parent/guardian                  |
| `student_id`   | BIGINT UNSIGNED | WordPress user ID of the child                            |
| `relationship` | VARCHAR(50)     | Free text shown in admin (e.g. "Parent", "Grandparent"); may be empty |
| `created_at`   | DATETIME        | Insertion time                                            |

`UNIQUE KEY guardian_student (guardian_id, student_id)` — the same pair can
never be linked twice.

The table is a link table, not a child record: the child's **name** is their
`display_name` on `wp_users`, and their birth year is the `us_birth_year`
user meta. Keeping them on the user row means the admin student screens,
`get_users()` ordering, and every existing `student_id` lookup keep working with
no special-casing.

### The legacy `us_date_of_birth` meta

This feature originally collected a full date of birth in `us_date_of_birth`.
Nothing writes that key any more. It is handled entirely inside
`GuardianService`:

- **Read** — `birthYear()` falls back to the year of the old date when
  `us_birth_year` is absent, so a child added before the change still shows one
  without a migration step.
- **Write** — `setBirthYear()` deletes `us_date_of_birth` on *every* save,
  including a save that clears the year. Without that the fallback would
  resurrect the old date on the next read and the year could never be cleared.

The upshot is a lazy migration: a child's full date survives until their record
is next edited, then goes for good. There is no bulk purge — a site that wants
the remaining old dates gone should delete the `us_date_of_birth` meta directly.

v1 is deliberately **one guardian per child**: `GuardianRepository::insert()`
refuses to link a child that already has a guardian. The unique key and the
guardian-side lookups already support many-to-many, so adding a second guardian
(separated parents) later is an insert, not a migration.

## Schema changes to existing tables

| Table | Change | Why |
|---|---|---|
| `us_payments` | `payer_id BIGINT UNSIGNED NOT NULL DEFAULT 0` + `KEY payer_id` | Who owes the money, when that is not the student |
| `us_credits` | `payer_id BIGINT UNSIGNED NOT NULL DEFAULT 0` + `KEY payer_id` | Which account holds the balance |
| `us_policy_acceptances` | `accepted_by BIGINT UNSIGNED NOT NULL DEFAULT 0` | Who actually clicked, when that is not the student |

All three default to `0`, read back as "same as `student_id`" (see
`Payment::payerOrStudent()`, `Credit::payerOrStudent()`,
`PolicyAcceptance::acceptorOrStudent()`), so **an existing row keeps its current
meaning whatever happens** — a pre-guardian payment is still owed by, and was
still accepted by, the student it names.

The installer additionally backfills them (`PaymentRepository::backfillPayerIds()`,
`CreditRepository::backfillPayerIds()`, `AcceptanceRepository::backfillAcceptedBy()`,
run from `Installer::migrateData()`), because the *balance* lookups key on
`payer_id` directly and an indexed `WHERE payer_id = 5` would not see a legacy row
still holding `0`. The backfill is idempotent — it only touches rows still at `0` —
and the `payerOrStudent()` fallbacks remain as the belt to its braces.

## Billing: the guardian is the payer, the child is the subject

- `us_payments.student_id` keeps naming **the child the lesson was for**, so
  per-child payment reporting is unchanged.
- `us_payments.payer_id` names **the guardian who owes it**. Payment notices,
  receipts and the Stripe intent all resolve the payer.
- `us_credits.payer_id` is where a **family balance** lives. A credit from one
  child's cancelled lesson is held by the guardian and can settle a sibling's
  charge; `CreditRepository::availableBalance()` and `consume()` operate on the
  payer.
- The **billing-method override** (`comp` / `card` / `etransfer`, user meta read
  by `BillingMethodResolver`) resolves against the payer, so comping a family is
  one setting on the guardian rather than one per child.

`PaymentService::createForRegistration()` takes the payer id alongside the
student id; `BookingEndpoint` and `ScheduledBillingRunner` both pass
`GuardianService::payerFor( $studentId )` — the child's guardian when they have
one, otherwise the student themselves.

Family discounts are **out of scope** for v1 but are not designed out: with the
payer on both the payment and the credit ledger, a discount rule has a family to
apply to.

## Registration

A **"I'm registering as a parent or guardian"** checkbox on the existing
`[us_student_register]` form (all three signup paths — personal invite, group
link, self-approval) reveals a repeatable child block. Ticking it requires at
least one child name.

Per child the form collects:
- **Name** (required)
- **Birth year** (optional, `us_birth_year` meta) — a four-digit year between
  1900 and the current year. Anything else is discarded rather than stored, so
  a typo cannot leave a nonsense age on the record.
- **Every account-scope registration question** (`Registration\Question`,
  `SCOPE_ACCOUNT`) — asked once per child, not once per guardian, because in
  practice they describe the student (instrument, level, school). The guardian
  answers them on the child's behalf; the answer row's `student_id` is the child.

Order of operations in `RegistrationPage::handleSubmit()`:

1. Validate the guardian's own fields (email, password, policies).
2. Validate **every** child block — a missing child name or a missing required
   per-child answer fails the whole submission **before** any user is created, so
   a half-registered family is never left behind.
3. Create the guardian user.
4. For each child: create the accountless user, link it, record its answers, and
   record the signup policy acceptances **against the child** with
   `accepted_by = <guardian>`.
5. Roll back — every child user created so far is deleted and the guardian user
   with them — if any child creation fails, so a partial family never persists.

A guardian who does not tick the box registers exactly as before; nothing about
the single-student flow changes.

### Policy acceptance

`us_policy_acceptances` records **one row per child** for each signup-scoped
policy, with:

- `student_id` = the child (who the policy binds),
- `accepted_by` = the guardian (who actually agreed),
- `registration_type = 'account'`, `registration_id` = the child's user ID.

The guardian also gets their own acceptance row (`student_id = accepted_by =
guardian`) whether or not they book for themselves — they agreed to the terms as
an account holder. This is the legally meaningful record: "guardian X accepted
policy version N on behalf of child Y at time T from IP Z".

Booking-scope policies are accepted at booking time by whoever is signed in;
`BookingEndpoint` passes the same `accepted_by` when a guardian books for a
child.

## Managing children

`[us_family]` (block: **Profile**) renders the guardian's manage-children screen:
list the children, add one, edit a name/birth year, remove one.

- **Add** creates another accountless child user and links it. Account-scope
  questions are asked here too, so a child added later carries the same
  information as one added at signup.
- **Edit** updates `display_name` and `us_birth_year`.
- **Remove** unlinks the child and **deletes the child user**, but only when the
  child has no lessons and no enrolments — a child with history is refused, so
  removing one can never orphan a lesson, payment or credit
  (`GuardianService::removeChild()`). The guardian is told to contact the studio
  instead.

Submissions are processed on `template_redirect` (like registration) and
post/redirect/get back to the page, so a refresh cannot resubmit.

## Booking

`GET /bookings` returns the lessons of the signed-in user **and of every child
they are guardian for**, each row carrying `student_id` and `student_name` so
the list can be grouped by child.

`POST /bookings` takes an optional **`student_id`**:

- absent or `0` → the current user books for themselves (unchanged),
- a child's id → the endpoint verifies with `GuardianService::canActFor()` that
  the current user is that child's guardian, and returns `403 forbidden` when
  they are not. **This is the authorisation boundary of the feature**: without
  it any student could book, and bill, against any user id they cared to send.

The booking form gains a "Who is this for?" `<select>`, rendered only when the
account has more than one person on it, so a single-student account's form is
unchanged.

**Children are listed first and the account holder last**
(`GuardianService::bookableStudents()`). The order is the whole point: a
guardian's normal case is booking for a child, so the default selection — the
one a parent gets by not touching the picker at all — is a child, never
themselves. Booking for the wrong child is a correctable inconvenience; silently
billing a parent's account for a lesson meant for their kid is the error worth
designing out. The guardian is still offered, last, so a parent taking lessons
alongside their children can book for themselves.

The list is rendered server-side into `data-students` on the page wrapper and
read by `assets/js/guardian.js`, which both the booking and group-class scripts
share.

`POST /bookings/<id>/cancel` accepts a cancellation from the lesson's student
**or** their guardian, subject to the same cancellation cutoff.

## Group classes

`POST /enrollments` carries the same optional `student_id` and the same
`canActFor()` check, `GET /enrollments` covers the household, and
`POST /enrollments/<id>/withdraw` accepts the guardian — group enrolment is the
other place a family books and pays, so it gets the identical treatment rather
than being left as a single-student-only path.

## Admin

- **Students list** gains a **Profile** column: a child links to its
  guardian's detail screen, a guardian lists its children as links. Children are
  listed alongside every other student rather than nested, so nothing about
  finding a student changes.
- **Student detail** gains a **Profile** panel — the guardian (for a child) or
  the children (for a guardian), each a link to the other's screen — and the
  credit balance shown is the **payer's** balance, labelled with whose it is, so
  an admin looking at a child sees the family balance that will actually settle
  their charges rather than an empty per-child one.
- Registration answers and policy acceptances on a child's screen show
  "accepted by <guardian>" where the acceptor differs from the student.

Creating or attaching a child from wp-admin is **out of scope** for v1; a studio
admin adds children through the guardian's own family screen or asks the
guardian to.

## Capabilities

No new capability. A child user holds the `us_student` role (so every existing
`student_id` capability check keeps working) but can never sign in
(`Guardian\ChildLoginGate` blocks `wp_authenticate_user` and forces
`user_has_cap` to withhold `book_lesson` from a child), so the role grants them
nothing in practice. Guardians act for children through
`GuardianService::canActFor()`, checked at every REST and form boundary, rather
than through a capability.

## Instructor view

Lesson lists show the student's name. Where that student is a child, the
instructor also sees the guardian's name and email — the contact they actually
need — via `GuardianService::contactFor()`.

## Implementation

- Models: `Unsupervised\Schedular\Guardian\GuardianLink`
- Repository: `Unsupervised\Schedular\Guardian\GuardianRepository`
- Service: `Unsupervised\Schedular\Guardian\GuardianService` (child creation,
  `canActFor()`, `payerFor()`, `contactFor()`, removal rules)
- Login block: `Unsupervised\Schedular\Guardian\ChildLoginGate`
- Frontend: `Unsupervised\Schedular\Guardian\FamilyPage` (`[us_family]`)
- Shared question field: `Unsupervised\Schedular\Registration\QuestionField`
  (one question rendered under a caller-supplied input name, so the same
  question can appear once per child without colliding)
- Front-end script: `assets/js/guardian.js` (the shared picker),
  `assets/js/register.js` (guardian toggle + "add another child")
- Extended: `Auth\RegistrationPage` (guardian checkbox, child blocks, per-child
  answers/acceptances, rollback), `Booking\BookingEndpoint` and
  `GroupClass\EnrollmentEndpoint` (`student_id` param + guardian
  authorisation, household listings), `Booking\BookingPage`,
  `GroupClass\GroupClassPage`, `Payment\PaymentService`,
  `Payment\PaymentRepository`, `Payment\CreditRepository`,
  `Payment\ScheduledBillingRunner` (one notice per payer),
  `Policy\AcceptanceRepository`, `Registration\RegistrationGate`,
  `Auth\StudentController`, `Installer` (backfills)
- Schema: `us_guardians`; `us_payments.payer_id`; `us_credits.payer_id`;
  `us_policy_acceptances.accepted_by`

## Tests

- `tests/Unit/Guardian/GuardianLinkTest.php`
- `tests/Unit/Guardian/GuardianRepositoryTest.php`
- `tests/Unit/Guardian/GuardianServiceTest.php`
- `tests/Unit/Guardian/ChildLoginGateTest.php`
- `tests/Unit/Guardian/FamilyPageTest.php`
- `tests/Unit/Auth/RegistrationPageTest.php` (guardian signup path)
- `tests/Unit/Booking/BookingEndpointTest.php` and
  `tests/Unit/GroupClass/EnrollmentEndpointTest.php` (booking/enrolling for a
  child, and the 403 when the caller is not the guardian)
- `tests/Unit/Booking/BookingPageTest.php` (children lead the embedded list)
- `tests/Unit/Payment/PaymentServiceTest.php`, `CreditRepositoryTest.php`,
  `ScheduledBillingRunnerTest.php` (payer, family balance, one notice)

## Related

`account-registration.md`, `lesson-booking.md`, `payments.md`, `credits.md`,
`group-classes.md`, `student-administration.md`, `policies.md`,
`registration-questions.md`.