refactor(form-field): extract FormFieldChildTableMorphScope abstract base

Closes the WS-5 family follow-up tracked as
FORM-BUILDER-MORPH-SCOPE-BASE-CLASS in BACKLOG.md. Per addendum
§Q3 Uitvoering across WS-5a/b/c/d, base-class extraction was
deliberately deferred until all four concrete morph-scope siblings
existed and the "what actually varies" question could be answered
empirically.

The answer is: nothing. All four siblings —
FormFieldBindingScope (WS-5a), FormFieldValidationRuleScope (WS-5b),
FormFieldConfigScope (WS-5b commit 5), and FormFieldOptionScope
(WS-5d) — are byte-equal in their apply() and resolveOrganisationId()
methods (Phase A diff verification clean: zero lines diverging
across all three pairwise comparisons).

Approach:

  - New abstract class FormFieldChildTableMorphScope holds the full
    UNION-over-two-owner-chains scope logic with the morph alias
    literals extracted as private constants
    (OWNER_TYPE_FIELD, OWNER_TYPE_LIBRARY) for one-location-of-truth.
  - The four concrete scopes become marker subclasses
    (`final class X extends FormFieldChildTableMorphScope {}`) — class
    identity preserved so every existing
    `withoutGlobalScope(FormFieldXScope::class)` call site in cascade
    observers, backfill migrations, and platform super_admin paths
    continues to work unchanged. The 4 test call sites (in the four
    *ScopeTest classes) work without modification.
  - Helper visibility stays `private` per YAGNI. If a future sibling
    needs to vary the morph aliases or owner-chain, the helpers
    promote to `protected` at that point.
  - Stylistic refinement vs. the four originals: `Organisation` and
    `Event` in resolveOrganisationId() now use `use` statements at
    the top of the file instead of inline `\App\Models\…` FQNs.

Net diff:
  Pre:  4 concrete scope files at ~106 lines each (~424 lines total)
  Post: 4 marker subclasses at 20 lines (80 total) +
        1 abstract base at 125 lines = 205 lines total
  Saving: ~219 lines of duplication removed.

Tests: 1208 passed (3260 assertions) → 1208 passed (3260 assertions).
Identical — public behaviour unchanged.

Larastan: clean (no new errors beyond baseline).
Rector: 357 → 355 dry-run suggestions (small reduction from the
deduplication; no apply in this commit).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/app/Models/Scopes/FormFieldValidationRuleScope.php

@@ -4,99 +4,17 @@ declare(strict_types=1);
 
 namespace App\Models\Scopes;
 
-use App\Models\FormBuilder\FormField;
-use App\Models\FormBuilder\FormFieldLibrary;
-use App\Models\FormBuilder\FormSchema;
-use Illuminate\Database\Eloquent\Builder;
-use Illuminate\Database\Eloquent\Model;
-use Illuminate\Database\Eloquent\Scope;
-
 /**
- * Multi-tenant isolation for `form_field_validation_rules`. Sibling to
- * `FormFieldBindingScope` — the two share the same UNION shape over the
- * polymorphic owner's two possible parents (`form_field → form_schema →
- * organisation_id` ∪ `form_field_library → organisation_id`).
+ * Marker subclass — see FormFieldChildTableMorphScope for the full
+ * UNION-over-two-owner-chains scope logic.
  *
- * Duplicate code with `FormFieldBindingScope` is acknowledged; base-class
- * extraction is deferred to WS-5d per the architect addendum Q3 decision:
- * premature abstraction from two is still premature, and WS-5d adds a
- * third sibling that will make what truly varies visible.
+ * The class identity is preserved so that existing
+ * `withoutGlobalScope(FormFieldValidationRuleScope::class)` call sites
+ * in cascade observers, backfill migrations, and platform super_admin
+ * paths continue to work unchanged. The behaviour is identical
+ * across all four siblings.
  *
- * Organisation context resolution mirrors `OrganisationScope` — explicit
- * override via constructor, then `organisation` / `event` route parameter
- * fallbacks. CLI, queues, and unauthenticated flows skip the scope.
- *
- * Escape hatch:
- * `FormFieldValidationRule::withoutGlobalScope(FormFieldValidationRuleScope::class)`.
+ * History: WS-5b; ARCH-FORM-BUILDER §17.4.3 and
+ * ARCH-CONSOLIDATION-ADDENDUM-2026-04-24.md §Q3 Uitvoering sections.
  */
-final class FormFieldValidationRuleScope implements Scope
-{
-    public function __construct(
-        private readonly ?string $organisationId = null,
-    ) {}
-
-    public function apply(Builder $builder, Model $model): void
-    {
-        $orgId = $this->resolveOrganisationId();
-        if ($orgId === null) {
-            return;
-        }
-
-        $fieldIds = FormField::query()
-            ->withoutGlobalScope(OrganisationScope::class)
-            ->whereIn(
-                'form_schema_id',
-                FormSchema::query()
-                    ->withoutGlobalScope(OrganisationScope::class)
-                    ->where('organisation_id', $orgId)
-                    ->select('id'),
-            )
-            ->select('id');
-
-        $libraryIds = FormFieldLibrary::query()
-            ->withoutGlobalScope(OrganisationScope::class)
-            ->where('organisation_id', $orgId)
-            ->select('id');
-
-        $table = $model->getTable();
-
-        $builder->where(function (Builder $outer) use ($table, $fieldIds, $libraryIds): void {
-            $outer->where(function (Builder $q) use ($table, $fieldIds): void {
-                $q->where("$table.owner_type", 'form_field')
-                    ->whereIn("$table.owner_id", $fieldIds);
-            })->orWhere(function (Builder $q) use ($table, $libraryIds): void {
-                $q->where("$table.owner_type", 'form_field_library')
-                    ->whereIn("$table.owner_id", $libraryIds);
-            });
-        });
-    }
-
-    private function resolveOrganisationId(): ?string
-    {
-        if ($this->organisationId !== null) {
-            return $this->organisationId;
-        }
-
-        $route = request()->route();
-        if ($route === null) {
-            return null;
-        }
-
-        $org = $route->parameter('organisation');
-
-        if ($org instanceof \App\Models\Organisation) {
-            return $org->id;
-        }
-
-        if (is_string($org) && $org !== '') {
-            return $org;
-        }
-
-        $event = $route->parameter('event');
-        if ($event instanceof \App\Models\Event) {
-            return $event->organisation_id;
-        }
-
-        return null;
-    }
-}
+final class FormFieldValidationRuleScope extends FormFieldChildTableMorphScope {}