diff --git a/api/app/Console/Commands/VerifyFormsDataIntegrity.php b/api/app/Console/Commands/VerifyFormsDataIntegrity.php
index 9fde1dbe..6a540078 100644
--- a/api/app/Console/Commands/VerifyFormsDataIntegrity.php
+++ b/api/app/Console/Commands/VerifyFormsDataIntegrity.php
@@ -128,28 +128,24 @@ final class VerifyFormsDataIntegrity extends Command
             ->havingRaw('COUNT(*) > 1')
             ->count();
 
-        // Binding registry cross-check
-        $binding = (array) config('form_binding', []);
+        // Binding registry cross-check (WS-5a: relational form_field_bindings).
+        $registry = (array) config('form_binding', []);
         $badBindings = 0;
-        $invalidBindings = DB::table('form_fields')->whereNotNull('binding')->select('binding')->get();
-        foreach ($invalidBindings as $row) {
-            $b = is_string($row->binding) ? json_decode($row->binding, true) : null;
-            if (! is_array($b) || ! isset($b['mode'], $b['entity'], $b['column'])) {
+        $bindingRows = DB::table('form_field_bindings')
+            ->select(['mode', 'target_entity', 'target_attribute'])
+            ->get();
+        foreach ($bindingRows as $row) {
+            if (! in_array($row->mode, ['entity_owned', 'mirrored'], true)) {
                 $badBindings++;
 
                 continue;
             }
-            if (! in_array($b['mode'], ['entity_owned', 'mirrored'], true)) {
+            if (! isset($registry[$row->target_entity][$row->target_attribute])) {
                 $badBindings++;
 
                 continue;
             }
-            if (! isset($binding[$b['entity']][$b['column']])) {
-                $badBindings++;
-
-                continue;
-            }
-            if (($binding[$b['entity']][$b['column']]['writable'] ?? false) !== true) {
+            if (($registry[$row->target_entity][$row->target_attribute]['writable'] ?? false) !== true) {
                 $badBindings++;
             }
         }
diff --git a/api/app/Http/Controllers/Api/V1/FormBuilder/FormFieldLibraryController.php b/api/app/Http/Controllers/Api/V1/FormBuilder/FormFieldLibraryController.php
index 35445199..dbdb55e0 100644
--- a/api/app/Http/Controllers/Api/V1/FormBuilder/FormFieldLibraryController.php
+++ b/api/app/Http/Controllers/Api/V1/FormBuilder/FormFieldLibraryController.php
@@ -10,6 +10,7 @@ use App\Http\Requests\Api\V1\FormBuilder\UpdateFormFieldLibraryRequest;
 use App\Http\Resources\FormBuilder\FormFieldLibraryResource;
 use App\Models\FormBuilder\FormFieldLibrary;
 use App\Models\Organisation;
+use App\Services\FormBuilder\FormFieldBindingService;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Resources\Json\AnonymousResourceCollection;
 use Illuminate\Support\Facades\Gate;
@@ -17,6 +18,10 @@ use Illuminate\Support\Str;
 
 final class FormFieldLibraryController extends Controller
 {
+    public function __construct(
+        private readonly FormFieldBindingService $bindingService,
+    ) {}
+
     public function index(Organisation $organisation): AnonymousResourceCollection
     {
         Gate::authorize('viewAny', [FormFieldLibrary::class, $organisation]);
@@ -42,6 +47,7 @@ final class FormFieldLibraryController extends Controller
         Gate::authorize('create', [FormFieldLibrary::class, $organisation]);
 
         $data = $request->validated();
+        $bindingSpec = $this->extractBindingSpec($data);
         $data['organisation_id'] = $organisation->id;
         $data['is_system'] = false;
         $data['is_active'] ??= true;
@@ -50,6 +56,10 @@ final class FormFieldLibraryController extends Controller
         /** @var FormFieldLibrary $library */
         $library = FormFieldLibrary::create($data);
 
+        if ($bindingSpec !== null) {
+            $this->bindingService->replaceBindings($library, [$bindingSpec]);
+        }
+
         return $this->created(new FormFieldLibraryResource($library));
     }
 
@@ -58,12 +68,46 @@ final class FormFieldLibraryController extends Controller
         $this->assertSameOrg($organisation, $fieldLibrary);
         Gate::authorize('update', $fieldLibrary);
 
-        $fieldLibrary->fill($request->validated());
+        $data = $request->validated();
+        $bindingProvided = array_key_exists('default_binding', $data);
+        $bindingSpec = $bindingProvided ? $this->extractBindingSpec($data) : null;
+
+        $fieldLibrary->fill($data);
         $fieldLibrary->save();
 
+        if ($bindingProvided) {
+            $this->bindingService->replaceBindings(
+                $fieldLibrary,
+                $bindingSpec === null ? [] : [$bindingSpec],
+            );
+        }
+
         return $this->success(new FormFieldLibraryResource($fieldLibrary));
     }
 
+    /**
+     * @param  array<string, mixed>  $data
+     * @return array{target_entity:string,target_attribute:string,mode:string,sync_direction?:?string}|null
+     */
+    private function extractBindingSpec(array &$data): ?array
+    {
+        if (! array_key_exists('default_binding', $data)) {
+            return null;
+        }
+        $raw = $data['default_binding'];
+        unset($data['default_binding']);
+        if (! is_array($raw) || $raw === []) {
+            return null;
+        }
+
+        return [
+            'target_entity' => (string) ($raw['entity'] ?? ''),
+            'target_attribute' => (string) ($raw['column'] ?? ''),
+            'mode' => (string) ($raw['mode'] ?? ''),
+            'sync_direction' => isset($raw['sync_direction']) ? (string) $raw['sync_direction'] : null,
+        ];
+    }
+
     public function destroy(Organisation $organisation, FormFieldLibrary $fieldLibrary): JsonResponse
     {
         $this->assertSameOrg($organisation, $fieldLibrary);
diff --git a/api/app/Models/FormBuilder/FormField.php b/api/app/Models/FormBuilder/FormField.php
index 20c319f9..513b2de4 100644
--- a/api/app/Models/FormBuilder/FormField.php
+++ b/api/app/Models/FormBuilder/FormField.php
@@ -59,7 +59,6 @@ final class FormField extends Model
         'is_unique',
         'is_pii',
         'display_width',
-        'binding',
         'conditional_logic',
         'role_restrictions',
         'translations',
@@ -72,7 +71,6 @@ final class FormField extends Model
     protected $casts = [
         'options' => 'array',
         'validation_rules' => 'array',
-        'binding' => 'array',
         'conditional_logic' => 'array',
         'role_restrictions' => 'array',
         'translations' => 'array',
diff --git a/api/app/Models/FormBuilder/FormFieldLibrary.php b/api/app/Models/FormBuilder/FormFieldLibrary.php
index b0362747..a23e31c1 100644
--- a/api/app/Models/FormBuilder/FormFieldLibrary.php
+++ b/api/app/Models/FormBuilder/FormFieldLibrary.php
@@ -38,7 +38,6 @@ final class FormFieldLibrary extends Model
         'validation_rules',
         'default_is_required',
         'default_is_filterable',
-        'default_binding',
         'translations',
         'description',
         'is_active',
@@ -48,7 +47,6 @@ final class FormFieldLibrary extends Model
     protected $casts = [
         'options' => 'array',
         'validation_rules' => 'array',
-        'default_binding' => 'array',
         'translations' => 'array',
         'default_is_required' => 'bool',
         'default_is_filterable' => 'bool',
diff --git a/api/app/Services/FormBuilder/FormFieldService.php b/api/app/Services/FormBuilder/FormFieldService.php
index 7f677cc1..53128b36 100644
--- a/api/app/Services/FormBuilder/FormFieldService.php
+++ b/api/app/Services/FormBuilder/FormFieldService.php
@@ -36,11 +36,17 @@ final class FormFieldService
         $data['form_schema_id'] = $schema->id;
         $data['sort_order'] ??= $this->nextSortOrder($schema);
 
+        $bindingSpec = $this->extractBindingSpec($data);
+
         $this->assertNoConditionalCycle($schema, null, $data['conditional_logic'] ?? null, $data['slug'] ?? null);
 
         /** @var FormField $field */
         $field = FormField::create($data);
 
+        if ($bindingSpec !== null) {
+            $this->bindingService->replaceBindings($field, [$bindingSpec]);
+        }
+
         $this->schemaService->bumpVersion($schema);
         $field->logFieldChange('field.created');
 
@@ -56,7 +62,13 @@ final class FormFieldService
         $schema = $field->schema;
         $this->assertNotFrozenForStructural($schema, $data);
 
-        if (array_key_exists('binding', $data) && $data['binding'] !== $field->binding) {
+        $bindingProvided = array_key_exists('binding', $data);
+        $rawBinding = $bindingProvided ? $data['binding'] : null;
+        $bindingSpec = $bindingProvided ? $this->extractBindingSpec($data) : null;
+
+        $currentBindingShape = $this->bindingService->toJsonShape($field->bindings()->first());
+
+        if ($bindingProvided && $this->bindingChanged($currentBindingShape, $rawBinding)) {
             $this->assertBindingChangeAllowed($field, $forceBindingChange);
         }
 
@@ -65,7 +77,7 @@ final class FormFieldService
         }
 
         $before = [
-            'binding' => $field->binding,
+            'binding' => $currentBindingShape,
             'is_filterable' => $field->is_filterable,
             'is_pii' => $field->is_pii,
             'field_type' => $field->field_type,
@@ -74,12 +86,16 @@ final class FormFieldService
         $field->fill($data);
         $field->save();
 
+        if ($bindingProvided) {
+            $this->bindingService->replaceBindings($field, $bindingSpec === null ? [] : [$bindingSpec]);
+        }
+
         $this->schemaService->bumpVersion($schema);
 
         $field->logFieldChange('field.updated', [
             'old' => $before,
             'new' => [
-                'binding' => $field->binding,
+                'binding' => $this->bindingService->toJsonShape($field->bindings()->first()),
                 'is_filterable' => $field->is_filterable,
                 'is_pii' => $field->is_pii,
                 'field_type' => $field->field_type,
@@ -93,6 +109,51 @@ final class FormFieldService
         return $field->refresh();
     }
 
+    /**
+     * @param  array<string, mixed>  $data
+     * @return array{target_entity:string,target_attribute:string,mode:string,sync_direction?:?string}|null
+     */
+    private function extractBindingSpec(array &$data): ?array
+    {
+        if (! array_key_exists('binding', $data)) {
+            return null;
+        }
+        $raw = $data['binding'];
+        unset($data['binding']);
+        if (! is_array($raw) || $raw === []) {
+            return null;
+        }
+
+        return [
+            'target_entity' => (string) ($raw['entity'] ?? ''),
+            'target_attribute' => (string) ($raw['column'] ?? ''),
+            'mode' => (string) ($raw['mode'] ?? ''),
+            'sync_direction' => isset($raw['sync_direction']) ? (string) $raw['sync_direction'] : null,
+        ];
+    }
+
+    /**
+     * @param  array<string, mixed>|null  $current  Pre-WS-5a ARCH §6.3 shape
+     * @param  array<string, mixed>|null  $next
+     */
+    private function bindingChanged(?array $current, ?array $next): bool
+    {
+        $normalise = static function (?array $value): array {
+            if ($value === null || $value === []) {
+                return [];
+            }
+
+            return [
+                'mode' => (string) ($value['mode'] ?? ''),
+                'entity' => (string) ($value['entity'] ?? ''),
+                'column' => (string) ($value['column'] ?? ''),
+                'sync_direction' => (string) ($value['sync_direction'] ?? ''),
+            ];
+        };
+
+        return $normalise($current) !== $normalise($next);
+    }
+
     public function delete(FormField $field, ?string $confirmedName = null): void
     {
         $schema = $field->schema;
diff --git a/api/app/Services/FormBuilder/FormSchemaService.php b/api/app/Services/FormBuilder/FormSchemaService.php
index 47d7a520..005ccae6 100644
--- a/api/app/Services/FormBuilder/FormSchemaService.php
+++ b/api/app/Services/FormBuilder/FormSchemaService.php
@@ -11,6 +11,7 @@ use App\Exceptions\FormBuilder\EditLockConflictException;
 use App\Exceptions\FormBuilder\PurposeRequirementsNotMetException;
 use App\FormBuilder\Purposes\PurposeRegistry;
 use App\Models\FormBuilder\FormField;
+use App\Models\FormBuilder\FormFieldBinding;
 use App\Models\FormBuilder\FormSchema;
 use App\Models\FormBuilder\FormSchemaSection;
 use App\Models\FormBuilder\FormSubmission;
@@ -133,8 +134,8 @@ final class FormSchemaService
      * purpose is bound by at least one field on the schema.
      *
      * Binding paths follow Pattern A notation (`{entity}.{attribute}`).
-     * In v1.0 we read `form_fields.binding` JSON; WS-5a will switch this
-     * to the relational `form_field_bindings` table.
+     * Sourced from the relational `form_field_bindings` table (WS-5a;
+     * ARCH §6.7, §17.3).
      */
     private function assertRequiredBindingsPresent(FormSchema $schema): void
     {
@@ -151,19 +152,16 @@ final class FormSchemaService
             return;
         }
 
-        $bound = [];
-        foreach ($schema->fields as $field) {
-            $binding = $field->binding;
-            if (! is_array($binding)) {
-                continue;
-            }
-            $entity = (string) ($binding['entity'] ?? '');
-            $column = (string) ($binding['column'] ?? '');
-            if ($entity === '' || $column === '') {
-                continue;
-            }
-            $bound[] = $entity.'.'.$column;
-        }
+        $fieldIds = $schema->fields()->pluck('id');
+
+        $bound = FormFieldBinding::query()
+            ->withoutGlobalScopes()
+            ->where('owner_type', 'form_field')
+            ->whereIn('owner_id', $fieldIds)
+            ->get(['target_entity', 'target_attribute'])
+            ->map(fn (FormFieldBinding $b) => $b->target_entity.'.'.$b->target_attribute)
+            ->unique()
+            ->all();
 
         $missing = array_values(array_diff($required, $bound));
         if ($missing !== []) {
diff --git a/api/app/Services/FormBuilder/FormValueService.php b/api/app/Services/FormBuilder/FormValueService.php
index ba5c66c3..9dbb80c7 100644
--- a/api/app/Services/FormBuilder/FormValueService.php
+++ b/api/app/Services/FormBuilder/FormValueService.php
@@ -291,18 +291,13 @@ final class FormValueService
 
     private function writeEntityMirror(FormSubmission $submission, FormField $field, mixed $raw): void
     {
-        $binding = $field->binding;
-        if (! is_array($binding) || ($binding['mode'] ?? null) === null) {
+        $binding = $field->bindings()->first();
+        if ($binding === null) {
             return;
         }
 
-        $mode = (string) $binding['mode'];
-        if (! in_array($mode, ['entity_owned', 'mirrored'], true)) {
-            return;
-        }
-
-        $entity = (string) ($binding['entity'] ?? '');
-        $column = (string) ($binding['column'] ?? '');
+        $entity = (string) $binding->target_entity;
+        $column = (string) $binding->target_attribute;
         if ($entity === '' || $column === '') {
             return;
         }
diff --git a/api/config/form_binding.php b/api/config/form_binding.php
index 02a1d248..3c2f1cef 100644
--- a/api/config/form_binding.php
+++ b/api/config/form_binding.php
@@ -35,6 +35,7 @@ return [
     ],
 
     'company' => [
+        'name' => ['type' => 'string', 'label' => 'Bedrijfsnaam', 'writable' => true],
         'contact_first_name' => ['type' => 'string', 'label' => 'Contact voornaam', 'writable' => true],
         'contact_last_name' => ['type' => 'string', 'label' => 'Contact achternaam', 'writable' => true],
         'contact_email' => ['type' => 'string', 'label' => 'Contact e-mail', 'writable' => true],
diff --git a/api/database/factories/FormBuilder/FormFieldFactory.php b/api/database/factories/FormBuilder/FormFieldFactory.php
index d40bc38e..206dd4b4 100644
--- a/api/database/factories/FormBuilder/FormFieldFactory.php
+++ b/api/database/factories/FormBuilder/FormFieldFactory.php
@@ -53,7 +53,6 @@ final class FormFieldFactory extends Factory
             'is_unique' => false,
             'is_pii' => false,
             'display_width' => FormFieldDisplayWidth::FULL,
-            'binding' => null,
             'conditional_logic' => null,
             'role_restrictions' => null,
             'translations' => null,
diff --git a/api/database/factories/FormBuilder/FormFieldLibraryFactory.php b/api/database/factories/FormBuilder/FormFieldLibraryFactory.php
index ae6720ab..b6da4b3e 100644
--- a/api/database/factories/FormBuilder/FormFieldLibraryFactory.php
+++ b/api/database/factories/FormBuilder/FormFieldLibraryFactory.php
@@ -36,7 +36,6 @@ final class FormFieldLibraryFactory extends Factory
             'validation_rules' => null,
             'default_is_required' => false,
             'default_is_filterable' => false,
-            'default_binding' => null,
             'translations' => null,
             'description' => fake('nl_NL')->sentence(),
             'is_active' => true,
diff --git a/api/database/migrations/2026_04_25_100001_drop_binding_json_columns.php b/api/database/migrations/2026_04_25_100001_drop_binding_json_columns.php
new file mode 100644
index 00000000..d1afb5cd
--- /dev/null
+++ b/api/database/migrations/2026_04_25_100001_drop_binding_json_columns.php
@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * WS-5a commit 3 of 4 — drops the legacy `form_fields.binding` and
+ * `form_field_library.default_binding` JSON columns now that every reader
+ * (pre-publish check, snapshot writer, API resources, mirror writer, field
+ * CRUD path, and library CRUD path) has been switched to the relational
+ * `form_field_bindings` table.
+ *
+ * Rollback re-adds both columns as nullable JSON but does NOT attempt to
+ * backfill. The full rollback path for WS-5a as a whole is to first roll
+ * back the table-creation migration (`2026_04_25_100000_create_form_field_bindings_table`),
+ * which genuinely reconstructs the JSON. Rolling back *only* this
+ * column-drop migration leaves the JSON columns empty on purpose —
+ * callers that need the old JSON state must roll back both steps.
+ */
+return new class extends Migration
+{
+    public function up(): void
+    {
+        if (Schema::hasColumn('form_fields', 'binding')) {
+            Schema::table('form_fields', function (Blueprint $table): void {
+                $table->dropColumn('binding');
+            });
+        }
+
+        if (Schema::hasColumn('form_field_library', 'default_binding')) {
+            Schema::table('form_field_library', function (Blueprint $table): void {
+                $table->dropColumn('default_binding');
+            });
+        }
+    }
+
+    public function down(): void
+    {
+        if (! Schema::hasColumn('form_fields', 'binding')) {
+            Schema::table('form_fields', function (Blueprint $table): void {
+                $table->json('binding')->nullable()->after('display_width');
+            });
+        }
+
+        if (! Schema::hasColumn('form_field_library', 'default_binding')) {
+            Schema::table('form_field_library', function (Blueprint $table): void {
+                $table->json('default_binding')->nullable()->after('default_is_filterable');
+            });
+        }
+    }
+};
diff --git a/api/database/seeders/FormBuilderDevSeeder.php b/api/database/seeders/FormBuilderDevSeeder.php
index 3fadc6d2..908820b2 100644
--- a/api/database/seeders/FormBuilderDevSeeder.php
+++ b/api/database/seeders/FormBuilderDevSeeder.php
@@ -99,7 +99,7 @@ final class FormBuilderDevSeeder
                     'is_required' => $field['is_required'] ?? false,
                     'is_filterable' => $field['is_filterable'] ?? false,
                     'is_pii' => $field['is_pii'] ?? false,
-                    'binding' => null,
+                    'binding' => null, // Pattern B — snapshot embeds null for form-owned fields.
                     'conditional_logic' => null,
                     'translations' => null,
                     'value_storage_hint' => $field['type']->recommendedValueStorageHint()->value,
@@ -372,7 +372,6 @@ final class FormBuilderDevSeeder
                 'is_admin_only' => false,
                 'is_pii' => false,
                 'display_width' => $def['display_width'] ?? 'full',
-                'binding' => null,
                 'role_restrictions' => null,
                 'value_storage_hint' => $def['value_storage_hint'] ?? FormValueStorageHint::JSON,
                 'sort_order' => $sortOrder + 1,
diff --git a/api/tests/Feature/FormBuilder/Bindings/BindingJsonColumnsDroppedTest.php b/api/tests/Feature/FormBuilder/Bindings/BindingJsonColumnsDroppedTest.php
new file mode 100644
index 00000000..91ab9af4
--- /dev/null
+++ b/api/tests/Feature/FormBuilder/Bindings/BindingJsonColumnsDroppedTest.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Feature\FormBuilder\Bindings;
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Facades\Schema;
+use Tests\TestCase;
+
+final class BindingJsonColumnsDroppedTest extends TestCase
+{
+    use RefreshDatabase;
+
+    public function test_form_fields_has_no_binding_column(): void
+    {
+        $this->assertFalse(Schema::hasColumn('form_fields', 'binding'));
+    }
+
+    public function test_form_field_library_has_no_default_binding_column(): void
+    {
+        $this->assertFalse(Schema::hasColumn('form_field_library', 'default_binding'));
+    }
+}
diff --git a/api/tests/Feature/FormBuilder/Bindings/FormFieldBindingMigrationTest.php b/api/tests/Feature/FormBuilder/Bindings/FormFieldBindingMigrationTest.php
index 235ceb43..865a2e45 100644
--- a/api/tests/Feature/FormBuilder/Bindings/FormFieldBindingMigrationTest.php
+++ b/api/tests/Feature/FormBuilder/Bindings/FormFieldBindingMigrationTest.php
@@ -4,8 +4,6 @@ declare(strict_types=1);
 
 namespace Tests\Feature\FormBuilder\Bindings;
 
-use App\Models\FormBuilder\FormField;
-use App\Models\FormBuilder\FormFieldLibrary;
 use App\Models\FormBuilder\FormSchema;
 use App\Models\Organisation;
 use Illuminate\Foundation\Testing\RefreshDatabase;
@@ -15,44 +13,48 @@ use Illuminate\Support\Str;
 use Tests\TestCase;
 
 /**
- * Seeds pre-migration JSON into `form_fields.binding` and
- * `form_field_library.default_binding`, then runs the migration forward
- * and back asserting both directions.
+ * Rolls back both WS-5a migrations (drop-columns + create-table), seeds
+ * pre-migration JSON into `form_fields.binding` and
+ * `form_field_library.default_binding`, then runs the migrations forward
+ * and back asserting:
  *
- * Forward: rows land in `form_field_bindings` with the correct
- * owner_type/owner_id + translated columns. Backward: JSON is
- * reconstructed into the source tables, table dropped.
+ *   - forward: rows land in form_field_bindings with the correct
+ *     owner_type/owner_id + translated columns; legacy JSON columns are
+ *     dropped afterwards.
+ *   - backward: the rollback pair genuinely reconstructs the JSON shape
+ *     before dropping the table.
+ *
+ * The "roll back both steps" contract is explicitly documented in
+ * `2026_04_25_100001_drop_binding_json_columns.php`.
  */
 final class FormFieldBindingMigrationTest extends TestCase
 {
     use RefreshDatabase;
 
-    private const MIGRATION_PATH = 'database/migrations/2026_04_25_100000_create_form_field_bindings_table.php';
-
-    public function test_forward_migration_backfills_rows_from_both_json_sources(): void
+    public function test_forward_migrations_backfill_rows_from_both_json_sources(): void
     {
-        // Start from a clean slate where form_field_bindings does not exist.
-        $this->artisan('migrate:rollback', ['--step' => 1])->assertSuccessful();
+        // Roll back: drop_binding_json_columns → create_form_field_bindings.
+        $this->artisan('migrate:rollback', ['--step' => 2])->assertSuccessful();
         $this->assertFalse(Schema::hasTable('form_field_bindings'));
+        $this->assertTrue(Schema::hasColumn('form_fields', 'binding'));
+        $this->assertTrue(Schema::hasColumn('form_field_library', 'default_binding'));
 
         [$fieldAId, $fieldCId, $fieldDId] = $this->seedFieldsWithBindingJson();
         [$libAId, $libCId] = $this->seedLibraryWithBindingJson();
 
-        $this->artisan('migrate', [
-            '--path' => self::MIGRATION_PATH,
-            '--realpath' => false,
-        ])->assertSuccessful();
+        $this->artisan('migrate')->assertSuccessful();
 
         $this->assertTrue(Schema::hasTable('form_field_bindings'));
+        $this->assertFalse(Schema::hasColumn('form_fields', 'binding'));
+        $this->assertFalse(Schema::hasColumn('form_field_library', 'default_binding'));
 
-        $rows = DB::table('form_field_bindings')->orderBy('owner_type')->orderBy('owner_id')->get();
+        $rows = DB::table('form_field_bindings')->get();
         $this->assertCount(5, $rows, 'Expected 3 field + 2 library rows');
 
         $fieldRowA = DB::table('form_field_bindings')
             ->where('owner_type', 'form_field')
             ->where('owner_id', $fieldAId)
             ->first();
-        $this->assertNotNull($fieldRowA);
         $this->assertSame('person', $fieldRowA->target_entity);
         $this->assertSame('email', $fieldRowA->target_attribute);
         $this->assertSame('entity_owned', $fieldRowA->mode);
@@ -65,7 +67,6 @@ final class FormFieldBindingMigrationTest extends TestCase
             ->where('owner_type', 'form_field')
             ->where('owner_id', $fieldCId)
             ->first();
-        $this->assertNotNull($fieldRowC);
         $this->assertSame('mirrored', $fieldRowC->mode);
         $this->assertSame('write_on_submit', $fieldRowC->sync_direction);
         $this->assertSame('user_profile', $fieldRowC->target_entity);
@@ -75,14 +76,12 @@ final class FormFieldBindingMigrationTest extends TestCase
             ->where('owner_type', 'form_field')
             ->where('owner_id', $fieldDId)
             ->first();
-        $this->assertNotNull($fieldRowD);
         $this->assertSame('entity_owned', $fieldRowD->mode);
 
         $libRowA = DB::table('form_field_bindings')
             ->where('owner_type', 'form_field_library')
             ->where('owner_id', $libAId)
             ->first();
-        $this->assertNotNull($libRowA);
         $this->assertSame('person', $libRowA->target_entity);
         $this->assertSame('first_name', $libRowA->target_attribute);
         $this->assertSame('entity_owned', $libRowA->mode);
@@ -91,46 +90,45 @@ final class FormFieldBindingMigrationTest extends TestCase
             ->where('owner_type', 'form_field_library')
             ->where('owner_id', $libCId)
             ->first();
-        $this->assertNotNull($libRowC);
         $this->assertSame('mirrored', $libRowC->mode);
     }
 
     public function test_rollback_reconstructs_json_and_drops_table(): void
     {
-        $this->artisan('migrate:rollback', ['--step' => 1])->assertSuccessful();
+        $this->artisan('migrate:rollback', ['--step' => 2])->assertSuccessful();
         [$fieldAId, , ] = $this->seedFieldsWithBindingJson();
         [$libAId, ] = $this->seedLibraryWithBindingJson();
 
-        $this->artisan('migrate', [
-            '--path' => self::MIGRATION_PATH,
-            '--realpath' => false,
-        ])->assertSuccessful();
+        $this->artisan('migrate')->assertSuccessful();
 
-        // Wipe the source JSON to prove the rollback writes back from rows.
-        DB::table('form_fields')->where('id', $fieldAId)->update(['binding' => null]);
-        DB::table('form_field_library')->where('id', $libAId)->update(['default_binding' => null]);
+        // Fully-forward state: columns gone, rows in form_field_bindings.
+        $this->assertFalse(Schema::hasColumn('form_fields', 'binding'));
+        $this->assertSame(5, DB::table('form_field_bindings')->count());
 
+        // Step back over drop_binding_json_columns → columns reappear empty.
         $this->artisan('migrate:rollback', ['--step' => 1])->assertSuccessful();
+        $this->assertTrue(Schema::hasColumn('form_fields', 'binding'));
+        $this->assertNull(DB::table('form_fields')->where('id', $fieldAId)->value('binding'));
 
+        // Step back over create_form_field_bindings → JSON reconstructed.
+        $this->artisan('migrate:rollback', ['--step' => 1])->assertSuccessful();
         $this->assertFalse(Schema::hasTable('form_field_bindings'));
 
         $field = DB::table('form_fields')->where('id', $fieldAId)->first();
         $this->assertNotNull($field->binding);
-        $json = json_decode((string) $field->binding, true);
         $this->assertSame([
             'mode' => 'entity_owned',
             'entity' => 'person',
             'column' => 'email',
-        ], $json);
+        ], json_decode((string) $field->binding, true));
 
         $lib = DB::table('form_field_library')->where('id', $libAId)->first();
         $this->assertNotNull($lib->default_binding);
-        $libJson = json_decode((string) $lib->default_binding, true);
         $this->assertSame([
             'mode' => 'entity_owned',
             'entity' => 'person',
             'column' => 'first_name',
-        ], $libJson);
+        ], json_decode((string) $lib->default_binding, true));
     }
 
     /** @return array{0:string,1:string,2:string} */
diff --git a/api/tests/Feature/FormBuilder/Bindings/PublishChecksRelationalBindingsTest.php b/api/tests/Feature/FormBuilder/Bindings/PublishChecksRelationalBindingsTest.php
new file mode 100644
index 00000000..508d62ee
--- /dev/null
+++ b/api/tests/Feature/FormBuilder/Bindings/PublishChecksRelationalBindingsTest.php
@@ -0,0 +1,106 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Feature\FormBuilder\Bindings;
+
+use App\Enums\FormBuilder\FormPurpose;
+use App\Exceptions\FormBuilder\PurposeRequirementsNotMetException;
+use App\Models\FormBuilder\FormField;
+use App\Models\FormBuilder\FormSchema;
+use App\Models\Organisation;
+use App\Models\User;
+use App\Services\FormBuilder\FormSchemaService;
+use Database\Seeders\RoleSeeder;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+/**
+ * The pre-publish check (`FormSchemaService::publish()`,
+ * `PurposeRequirementsNotMetException`, ARCH §17.3) now reads from
+ * `form_field_bindings`. External contract (purposeSlug +
+ * missingBindings[]) unchanged.
+ */
+final class PublishChecksRelationalBindingsTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private Organisation $org;
+
+    private User $actor;
+
+    private FormSchemaService $service;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->seed(RoleSeeder::class);
+
+        $this->org = Organisation::factory()->create();
+        $this->actor = User::factory()->create();
+        $this->org->users()->attach($this->actor, ['role' => 'org_admin']);
+        $this->actor->assignRole('org_admin');
+        setPermissionsTeamId($this->org->id);
+
+        $this->service = $this->app->make(FormSchemaService::class);
+    }
+
+    public function test_publish_succeeds_when_all_required_bindings_are_in_relational_table(): void
+    {
+        $schema = $this->service->create(
+            $this->org,
+            ['name' => 'ER', 'purpose' => FormPurpose::EVENT_REGISTRATION->value],
+            $this->actor,
+        );
+
+        FormField::factory()->withEntityBinding('person', 'email')->create(['form_schema_id' => $schema->id]);
+        FormField::factory()->withEntityBinding('person', 'first_name')->create(['form_schema_id' => $schema->id]);
+        FormField::factory()->withEntityBinding('person', 'last_name')->create(['form_schema_id' => $schema->id]);
+
+        $published = $this->service->publish($schema->fresh(), $this->actor);
+
+        $this->assertTrue((bool) $published->is_published);
+    }
+
+    public function test_publish_fails_when_required_binding_missing_reports_exact_paths(): void
+    {
+        $schema = $this->service->create(
+            $this->org,
+            ['name' => 'ER-partial', 'purpose' => FormPurpose::EVENT_REGISTRATION->value],
+            $this->actor,
+        );
+        FormField::factory()->withEntityBinding('person', 'email')->create(['form_schema_id' => $schema->id]);
+
+        try {
+            $this->service->publish($schema->fresh(), $this->actor);
+            $this->fail('Expected PurposeRequirementsNotMetException');
+        } catch (PurposeRequirementsNotMetException $e) {
+            $this->assertSame('event_registration', $e->purposeSlug);
+            $this->assertSame(['person.first_name', 'person.last_name'], $e->missingBindings);
+        }
+    }
+
+    public function test_publish_ignores_bindings_belonging_to_other_schemas(): void
+    {
+        $schemaA = $this->service->create(
+            $this->org,
+            ['name' => 'A', 'purpose' => FormPurpose::SUPPLIER_INTAKE->value],
+            $this->actor,
+        );
+        $schemaB = $this->service->create(
+            $this->org,
+            ['name' => 'B', 'purpose' => FormPurpose::SUPPLIER_INTAKE->value],
+            $this->actor,
+        );
+
+        FormField::factory()->withEntityBinding('company', 'contact_email')->create(['form_schema_id' => $schemaB->id]);
+
+        try {
+            $this->service->publish($schemaA->fresh(), $this->actor);
+            $this->fail('Expected PurposeRequirementsNotMetException');
+        } catch (PurposeRequirementsNotMetException $e) {
+            $this->assertSame('supplier_intake', $e->purposeSlug);
+            $this->assertSame(['company.name'], $e->missingBindings);
+        }
+    }
+}
diff --git a/api/tests/Feature/FormBuilder/FormFieldApiTest.php b/api/tests/Feature/FormBuilder/FormFieldApiTest.php
index 70215205..ae5214c4 100644
--- a/api/tests/Feature/FormBuilder/FormFieldApiTest.php
+++ b/api/tests/Feature/FormBuilder/FormFieldApiTest.php
@@ -71,7 +71,6 @@ final class FormFieldApiTest extends TestCase
         Sanctum::actingAs($this->admin);
         $field = FormField::factory()->create([
             'form_schema_id' => $this->schema->id,
-            'binding' => null,
         ]);
         FormSubmission::factory()->create([
             'form_schema_id' => $this->schema->id,
@@ -92,7 +91,6 @@ final class FormFieldApiTest extends TestCase
         Sanctum::actingAs($this->admin);
         $field = FormField::factory()->create([
             'form_schema_id' => $this->schema->id,
-            'binding' => null,
         ]);
         FormSubmission::factory()->create([
             'form_schema_id' => $this->schema->id,
diff --git a/api/tests/Feature/FormBuilder/Purposes/PurposeSchemaLifecycleTest.php b/api/tests/Feature/FormBuilder/Purposes/PurposeSchemaLifecycleTest.php
index 1224cc59..4472ac60 100644
--- a/api/tests/Feature/FormBuilder/Purposes/PurposeSchemaLifecycleTest.php
+++ b/api/tests/Feature/FormBuilder/Purposes/PurposeSchemaLifecycleTest.php
@@ -148,12 +148,13 @@ final class PurposeSchemaLifecycleTest extends TestCase
 
     private function addBindingField(FormSchema $schema, string $entity, string $column, string $slug): FormField
     {
-        return FormField::factory()->create([
-            'form_schema_id' => $schema->id,
-            'field_type' => FormFieldType::TEXT,
-            'slug' => $slug,
-            'label' => ucfirst($slug),
-            'binding' => ['mode' => 'entity_owned', 'entity' => $entity, 'column' => $column],
-        ]);
+        return FormField::factory()
+            ->withEntityBinding($entity, $column)
+            ->create([
+                'form_schema_id' => $schema->id,
+                'field_type' => FormFieldType::TEXT,
+                'slug' => $slug,
+                'label' => ucfirst($slug),
+            ]);
     }
 }
diff --git a/api/tests/Unit/Models/FormBuilder/FormFieldTest.php b/api/tests/Unit/Models/FormBuilder/FormFieldTest.php
index 7029a76c..1f3ba099 100644
--- a/api/tests/Unit/Models/FormBuilder/FormFieldTest.php
+++ b/api/tests/Unit/Models/FormBuilder/FormFieldTest.php
@@ -32,20 +32,29 @@ final class FormFieldTest extends TestCase
         $this->assertIsString($field->fresh()->field_type);
     }
 
-    public function test_form_field_casts_binding_and_translations_to_array(): void
+    public function test_form_field_casts_translations_to_array(): void
     {
         $field = FormField::factory()->create([
-            'binding' => ['mode' => 'entity_owned', 'entity' => 'person', 'column' => 'first_name'],
             'translations' => ['en' => ['label' => 'First name']],
         ]);
         $fresh = $field->fresh();
 
-        $this->assertIsArray($fresh->binding);
-        $this->assertSame('entity_owned', $fresh->binding['mode']);
         $this->assertIsArray($fresh->translations);
         $this->assertSame('First name', $fresh->translations['en']['label']);
     }
 
+    public function test_form_field_bindings_relation_exposes_relational_rows(): void
+    {
+        $field = FormField::factory()
+            ->withEntityBinding('person', 'first_name')
+            ->create();
+
+        $binding = $field->bindings()->first();
+        $this->assertNotNull($binding);
+        $this->assertSame('person', $binding->target_entity);
+        $this->assertSame('first_name', $binding->target_attribute);
+    }
+
     public function test_form_field_has_many_values(): void
     {
         $schema = FormSchema::factory()->create();