diff --git a/app/Helpers/Helper.php b/app/Helpers/Helper.php
index 45d1b392f8..b8ed973d60 100644
--- a/app/Helpers/Helper.php
+++ b/app/Helpers/Helper.php
@@ -1111,15 +1111,21 @@ class Helper
                 if (is_array($rule)) {
                     if (in_array('required', $rule)) {
                         return true;
-                    } else {
-                        return false;
                     }
-                } else {
-                    if (strpos($rule, 'required') === false) {
-                        return false;
-                    } else {
+                    if (in_array('fmcs_company', $rule) && self::fmcsCompanyIsCurrentlyRequired()) {
                         return true;
                     }
+
+                    return false;
+                } else {
+                    if (strpos($rule, 'required') !== false) {
+                        return true;
+                    }
+                    if (strpos($rule, 'fmcs_company') !== false && self::fmcsCompanyIsCurrentlyRequired()) {
+                        return true;
+                    }
+
+                    return false;
                 }
             }
         }
@@ -1127,6 +1133,35 @@ class Helper
         return false;
     }
 
+    /**
+     * Mirror of the fmcs_company validator's runtime condition, used by
+     * checkIfRequired() so Blade fields render the "required" indicator
+     * (asterisk / aria-required) in the same conditions the backend will
+     * reject a blank submission. See ValidationServiceProvider.
+     */
+    protected static function fmcsCompanyIsCurrentlyRequired(): bool
+    {
+        $settings = \App\Models\Setting::getSettings();
+        if (! $settings->full_multiple_companies_support) {
+            return false;
+        }
+        if ((bool) $settings->null_company_is_floater) {
+            return false;
+        }
+        if (! auth()->check()) {
+            return false;
+        }
+        $actor = auth()->user();
+        if ($actor->isSuperUser()) {
+            return false;
+        }
+
+        // Uncompanied users work in the null pseudo-company namespace
+        // under strict mode; null IS a valid company id for them, so
+        // don't render the field as required.
+        return $actor->companies()->exists();
+    }
+
     /**
      * Return the numeric max length declared for a field in the model's
      * validation rules (looks for `max:N`). Returns null when the model, field,
diff --git a/app/Http/Controllers/Users/BulkUsersController.php b/app/Http/Controllers/Users/BulkUsersController.php
index bf836813fc..0eed29b406 100644
--- a/app/Http/Controllers/Users/BulkUsersController.php
+++ b/app/Http/Controllers/Users/BulkUsersController.php
@@ -275,8 +275,25 @@ class BulkUsersController extends Controller
             $allowedIds = Company::getIdsForCurrentUser($bulkCompanyIds);
         }
 
-        // Floater-mode self-elevation guard (#19200). See User::canGrantFloaterStatus.
         $wouldClear = $clearCompanies || ($bulkCompanyIds && empty($allowedIds));
+
+        // Strict-FMCS #19192 gate — mirrors the branch in SaveUserRequest
+        // so bulk-editing a batch to clear all company memberships in
+        // strict mode is blocked for companied non-superusers. Fires
+        // before the older floater-mode gate so its more specific error
+        // wins when both apply. Skips uncompanied actors because they
+        // legitimately operate in the null pseudo-company namespace in
+        // strict mode; nulling pivots there is their normal workflow,
+        // not a self-escalation attempt.
+        $settings = Setting::getSettings();
+        $strictFmcs = $settings->full_multiple_companies_support && ! $settings->null_company_is_floater;
+        $actor = auth()->user();
+        if ($wouldClear && $strictFmcs && ! $actor->isSuperUser() && $actor->companies()->exists()) {
+            return redirect()->route('users.index')
+                ->with('error', trans('validation.fmcs_company', ['attribute' => trans('general.company')]));
+        }
+
+        // Floater-mode self-elevation guard (#19200). See User::canGrantFloaterStatus.
         if ($wouldClear && ! auth()->user()->canGrantFloaterStatus()) {
             return redirect()->route('users.index')
                 ->with('error', trans('admin/users/general.cannot_make_floater'));
diff --git a/app/Http/Requests/SaveUserRequest.php b/app/Http/Requests/SaveUserRequest.php
index 3bda0b5a00..b42a4b2d1d 100644
--- a/app/Http/Requests/SaveUserRequest.php
+++ b/app/Http/Requests/SaveUserRequest.php
@@ -75,10 +75,18 @@ class SaveUserRequest extends FormRequest
 
     /**
      * Block non-superusers from saving a user whose resulting company set would
-     * be empty *while floater mode is enabled* — that combination promotes the
-     * target user to a system-wide floater (sees everything), and is the
-     * privilege-escalation vector flagged in #19200. Superusers can still make
-     * floaters intentionally. Applies to web and API store/update.
+     * be empty:
+     *
+     *  - Floater mode ON:  the resulting user would become a system-wide
+     *    floater (sees everything). That's the privilege-escalation vector
+     *    flagged in #19200 — only superusers (and users already able to grant
+     *    floater status) may do this deliberately.
+     *  - Floater mode OFF (strict FMCS): the resulting user would land with
+     *    an empty pivot and be immediately invisible to the creator's own
+     *    scope. That's the visibility bug flagged in #19192 — only superusers
+     *    (whose scope reaches nulls) may do this.
+     *
+     * Applies to both web and API store/update.
      */
     public function withValidator(Validator $validator): void
     {
@@ -91,7 +99,7 @@ class SaveUserRequest extends FormRequest
             // the PHPUnit/Pest runner, which also reports as "in console" but
             // is using the HTTP stack and must see the gate fire.
             $inActualConsole = app()->runningInConsole() && ! app()->runningUnitTests();
-            if ($inActualConsole || auth()->user()?->canGrantFloaterStatus()) {
+            if ($inActualConsole) {
                 return;
             }
 
@@ -107,7 +115,28 @@ class SaveUserRequest extends FormRequest
             $effective = Company::getIdsForCurrentUser($submitted);
 
             if (empty($effective)) {
-                $validator->errors()->add('company_ids', trans('admin/users/general.cannot_make_floater'));
+                $settings = Setting::getSettings();
+                $actor = auth()->user();
+                $creatorIsSuper = (bool) $actor?->isSuperUser();
+                $creatorHasCompanies = (bool) $actor?->companies()->exists();
+                $strictFmcs = $settings->full_multiple_companies_support && ! $settings->null_company_is_floater;
+
+                // Strict-FMCS #19192 gate — hits before the older floater
+                // gate so its more specific error message wins when both
+                // apply. Skips uncompanied actors because they legitimately
+                // work in the null pseudo-company namespace under strict
+                // mode; forcing them to add memberships they don't have
+                // would lock them out of their normal workflow.
+                if ($strictFmcs && ! $creatorIsSuper && $creatorHasCompanies) {
+                    $validator->errors()->add('company_ids', trans('validation.fmcs_company', ['attribute' => trans('general.company')]));
+
+                    return;
+                }
+
+                // Original #19200 floater-grant gate.
+                if (! $actor?->canGrantFloaterStatus()) {
+                    $validator->errors()->add('company_ids', trans('admin/users/general.cannot_make_floater'));
+                }
             }
         });
     }
diff --git a/app/Http/Requests/UpdateAssetRequest.php b/app/Http/Requests/UpdateAssetRequest.php
index 5f5e98a199..19587ac4f5 100644
--- a/app/Http/Requests/UpdateAssetRequest.php
+++ b/app/Http/Requests/UpdateAssetRequest.php
@@ -48,6 +48,23 @@ class UpdateAssetRequest extends ImageUploadRequest
         // route through checkOut() and produce the required audit-log entry).
         unset($assetRules['assigned_to'], $assetRules['assigned_type']);
 
+        // Strip fmcs_company from the request-level company_id rule. It's an
+        // implicit rule (fires on null/absent) which is right for the
+        // model-level ValidatingTrait check on save, but wrong at the
+        // request-level PATCH context — omitting company_id means "don't
+        // change it," not "set to null." The model-level rule still
+        // catches a genuine null-value save. StoreAssetRequest and
+        // BulkUpdateAssetsRequest inherit from this indirectly via
+        // parent classes; the store path keeps the rule (create should
+        // require Company), the bulk update path is already covered by
+        // this strip since it extends UpdateAssetRequest.
+        if (isset($assetRules['company_id']) && is_array($assetRules['company_id'])) {
+            $assetRules['company_id'] = array_values(array_filter(
+                $assetRules['company_id'],
+                fn ($rule) => $rule !== 'fmcs_company',
+            ));
+        }
+
         // On the singular endpoint we can tell Rule::unique to ignore the
         // asset being updated. Bulk (BulkUpdateAssetsRequest) overrides this
         // to null because it would have to ignore N different ids at once,
diff --git a/app/Models/Accessory.php b/app/Models/Accessory.php
index a7e7169cc9..b9b5804f2d 100755
--- a/app/Models/Accessory.php
+++ b/app/Models/Accessory.php
@@ -82,7 +82,7 @@ class Accessory extends SnipeModel
         'name' => 'required|max:255',
         'qty' => 'nullable|integer|min:0',
         'category_id' => 'required|integer|exists:categories,id',
-        'company_id' => 'integer|nullable|exists:companies,id',
+        'company_id' => 'integer|nullable|exists:companies,id|fmcs_company',
         'location_id' => 'exists:locations,id|nullable|fmcs_location',
         'min_amt' => 'integer|min:0|nullable',
         'purchase_cost' => 'numeric|nullable|gte:0|max:99999999999999999.99',
diff --git a/app/Models/Asset.php b/app/Models/Asset.php
index d91ad1d22e..7998362412 100644
--- a/app/Models/Asset.php
+++ b/app/Models/Asset.php
@@ -113,7 +113,7 @@ class Asset extends Depreciable
         'status_id' => ['required', 'integer', 'exists:status_labels,id'],
         'asset_tag' => ['required', 'min:1', 'max:255', 'unique_undeleted:assets,asset_tag', 'not_array'],
         'name' => ['nullable', 'max:255'],
-        'company_id' => ['nullable', 'integer', 'exists:companies,id'],
+        'company_id' => ['nullable', 'integer', 'exists:companies,id', 'fmcs_company'],
         'warranty_months' => ['nullable', 'numeric', 'digits_between:0,240'],
         'last_checkout' => ['nullable', 'date_format:Y-m-d H:i:s'],
         'last_checkin' => ['nullable', 'date_format:Y-m-d H:i:s'],
diff --git a/app/Models/Component.php b/app/Models/Component.php
index 5e6053cb97..cb3201bb3a 100644
--- a/app/Models/Component.php
+++ b/app/Models/Component.php
@@ -47,7 +47,7 @@ class Component extends SnipeModel
         'qty' => 'required|integer|min:1',
         'category_id' => 'required|integer|exists:categories,id',
         'supplier_id' => 'nullable|integer|exists:suppliers,id',
-        'company_id' => 'integer|nullable|exists:companies,id',
+        'company_id' => 'integer|nullable|exists:companies,id|fmcs_company',
         'location_id' => 'exists:locations,id|nullable|fmcs_location',
         'min_amt' => 'integer|min:0|nullable',
         'purchase_date' => 'date_format:Y-m-d|nullable',
diff --git a/app/Models/Consumable.php b/app/Models/Consumable.php
index a2f211ff15..9b3df72b01 100644
--- a/app/Models/Consumable.php
+++ b/app/Models/Consumable.php
@@ -48,7 +48,7 @@ class Consumable extends SnipeModel
         'name' => 'required|max:255',
         'qty' => 'required|integer|min:0|max:99999',
         'category_id' => 'required|integer',
-        'company_id' => 'integer|nullable|exists:companies,id',
+        'company_id' => 'integer|nullable|exists:companies,id|fmcs_company',
         'location_id' => 'exists:locations,id|nullable|fmcs_location',
         'min_amt' => 'integer|min:0|max:99999|nullable',
         'purchase_cost' => 'numeric|nullable|gte:0|max:99999999999999999.99',
diff --git a/app/Models/Department.php b/app/Models/Department.php
index 2805dca67a..48b62bd5f1 100644
--- a/app/Models/Department.php
+++ b/app/Models/Department.php
@@ -46,7 +46,7 @@ class Department extends SnipeModel
     protected $rules = [
         'name' => 'required|string|max:255|is_unique_across_company_and_location:departments,name',
         'location_id' => 'numeric|nullable|exists:locations,id',
-        'company_id' => 'numeric|nullable|exists:companies,id',
+        'company_id' => 'numeric|nullable|exists:companies,id|fmcs_company',
         'manager_id' => 'numeric|nullable|exists:users,id',
         'phone' => 'string|max:255|nullable',
         'fax' => 'string|max:255|nullable',
diff --git a/app/Models/License.php b/app/Models/License.php
index e1c91de56d..6f78fba239 100755
--- a/app/Models/License.php
+++ b/app/Models/License.php
@@ -59,7 +59,7 @@ class License extends Depreciable
         'license_name' => 'string|nullable|max:100',
         'notes' => 'string|nullable',
         'category_id' => 'required|exists:categories,id',
-        'company_id' => 'integer|nullable|exists:companies,id',
+        'company_id' => 'integer|nullable|exists:companies,id|fmcs_company',
         'purchase_cost' => 'numeric|nullable|gte:0|max:99999999999999999.99',
         'purchase_date' => 'date_format:Y-m-d|nullable|max:10|required_with:depreciation_id',
         'expiration_date' => 'date_format:Y-m-d|nullable|max:10',
diff --git a/app/Models/Location.php b/app/Models/Location.php
index c5d32ba990..e4507cc110 100755
--- a/app/Models/Location.php
+++ b/app/Models/Location.php
@@ -43,7 +43,7 @@ class Location extends SnipeModel
         'zip' => 'max:10|nullable',
         'manager_id' => 'exists:users,id|nullable',
         'parent_id' => 'nullable|exists:locations,id|non_circular:locations,id',
-        'company_id' => 'integer|nullable|exists:companies,id',
+        'company_id' => 'integer|nullable|exists:companies,id|fmcs_company',
     ];
 
     protected $casts = [
diff --git a/app/Providers/ValidationServiceProvider.php b/app/Providers/ValidationServiceProvider.php
index 011967c794..ba699ab1ca 100644
--- a/app/Providers/ValidationServiceProvider.php
+++ b/app/Providers/ValidationServiceProvider.php
@@ -452,6 +452,60 @@ class ValidationServiceProvider extends ServiceProvider
             );
         });
 
+        // Enforces "Company must be picked" when FMCS is on AND
+        // null_company_is_floater is disabled (strict mode). Without this
+        // rule a companied non-superuser can save a form with an unset
+        // company dropdown, land a row with company_id=NULL, and then
+        // have that row instantly filtered out of their own view by the
+        // strict-mode scope. See #19192. Passes when:
+        //  - FMCS is off (nothing to enforce)
+        //  - null_company_is_floater is on (nulls are legal floaters)
+        //  - value is present (form was filled in)
+        //  - no auth context (CLI, seeders, or importers bypass, matching
+        //    the SaveUserRequest cannot_make_floater gate posture)
+        //  - acting user is a superuser (they see everything, so a null
+        //    is an explicit choice, not an accident)
+        //  - acting user has NO company memberships. In strict mode
+        //    such users legitimately operate in the null "pseudo-company"
+        //    namespace, where Company::scopeCompanyablesDirectly scopes
+        //    them to whereNull($company_id) and null IS a valid company
+        //    id for them. Forcing them to pick a non-null company would
+        //    both lock them out of their normal workflow and produce a
+        //    row they wouldn't be able to see afterward.
+        // extendImplicit (not extend) because Laravel skips "explicit"
+        // rules when the field is null or absent. Since the whole point
+        // of fmcs_company is to fire ON blank submissions, it must run
+        // implicitly. Same reason built-in rules like `required`,
+        // `filled`, `present`, `accepted` are all registered implicit.
+        Validator::extendImplicit('fmcs_company', function ($attribute, $value, $parameters, $validator) {
+            $settings = Setting::getSettings();
+            if (! $settings->full_multiple_companies_support) {
+                return true;
+            }
+            if ((bool) $settings->null_company_is_floater) {
+                return true;
+            }
+            if (! empty($value)) {
+                return true;
+            }
+            if (! auth()->check()) {
+                return true;
+            }
+            $actor = auth()->user();
+            if ($actor->isSuperUser()) {
+                return true;
+            }
+            if (! $actor->companies()->exists()) {
+                return true;
+            }
+
+            return false;
+        });
+
+        Validator::replacer('fmcs_company', function ($message) {
+            return str_replace(':attribute', trans('general.company'), $message);
+        });
+
         // Validates that the company of the validated object matches the company of the location in case of scoped locations
         Validator::extend('fmcs_location', function ($attribute, $value, $parameters, $validator) {
             $settings = Setting::getSettings();
diff --git a/resources/lang/en-US/validation.php b/resources/lang/en-US/validation.php
index 49736251bf..9d172a7ec2 100644
--- a/resources/lang/en-US/validation.php
+++ b/resources/lang/en-US/validation.php
@@ -177,6 +177,7 @@ return [
     'ulid' => 'The :attribute field must be a valid ULID.',
     'uuid' => 'The :attribute field must be a valid UUID.',
     'valid_css_color' => 'The :attribute field must be a valid CSS color (hex, rgb, rgba, hsl, or hsla).',
+    'fmcs_company' => 'The :attribute field is required because full multiple companies support is enabled and floaters are not allowed.',
     'fmcs_location' => 'Location ":location" belongs to :location_company, which does not match the selected company.',
     'is_unique_across_company_and_location' => 'The :attribute must be unique within the selected company and location.',
 
diff --git a/tests/Feature/Fmcs/FmcsCompanyRuleWiringTest.php b/tests/Feature/Fmcs/FmcsCompanyRuleWiringTest.php
new file mode 100644
index 0000000000..3571f0190f
--- /dev/null
+++ b/tests/Feature/Fmcs/FmcsCompanyRuleWiringTest.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace Tests\Feature\Fmcs;
+
+use App\Models\Accessory;
+use App\Models\Asset;
+use App\Models\Component;
+use App\Models\Consumable;
+use App\Models\Department;
+use App\Models\License;
+use App\Models\Location;
+use PHPUnit\Framework\Attributes\DataProvider;
+use Tests\TestCase;
+
+/**
+ * Regression coverage for GitHub issue #19192, part 2 of 4.
+ *
+ * Sanity check that every Companyable model the reporter listed carries
+ * the fmcs_company validator on its $rules['company_id'] entry. The rule
+ * itself is exercised in FmcsCompanyValidatorTest. This file just guards
+ * against a future refactor accidentally dropping the rule off one of
+ * the model rule arrays and quietly re-opening the #19192 hole.
+ */
+class FmcsCompanyRuleWiringTest extends TestCase
+{
+    #[DataProvider('companyableModelProvider')]
+    public function test_model_rules_include_fmcs_company_for_company_id(string $modelClass)
+    {
+        $rules = $modelClass::rules();
+        $this->assertArrayHasKey('company_id', $rules, $modelClass.' should declare a company_id rule');
+
+        $companyRule = $rules['company_id'];
+        $ruleString = is_array($companyRule) ? implode('|', $companyRule) : $companyRule;
+
+        $this->assertStringContainsString(
+            'fmcs_company',
+            $ruleString,
+            $modelClass.'::rules()[company_id] must include the fmcs_company validator so strict-FMCS mode rejects blank submissions',
+        );
+    }
+
+    public static function companyableModelProvider(): array
+    {
+        return [
+            'Asset' => [Asset::class],
+            'License' => [License::class],
+            'Accessory' => [Accessory::class],
+            'Consumable' => [Consumable::class],
+            'Component' => [Component::class],
+            'Department' => [Department::class],
+            'Location' => [Location::class],
+        ];
+    }
+}
diff --git a/tests/Feature/Fmcs/FmcsCompanyValidatorTest.php b/tests/Feature/Fmcs/FmcsCompanyValidatorTest.php
new file mode 100644
index 0000000000..6c07282a3e
--- /dev/null
+++ b/tests/Feature/Fmcs/FmcsCompanyValidatorTest.php
@@ -0,0 +1,132 @@
+<?php
+
+namespace Tests\Feature\Fmcs;
+
+use App\Models\Company;
+use App\Models\User;
+use Illuminate\Support\Facades\Validator;
+use Tests\TestCase;
+
+/**
+ * Regression coverage for GitHub issue #19192, part 1 of 4.
+ *
+ * Exercises the fmcs_company validator in isolation across the settings
+ * and actor context matrix. Per Snipe's FMCS adversarial-tests memory,
+ * cover strict and floater and non-FMCS with superuser and non-superuser
+ * actors, plus the CLI (no-auth) posture and the pseudo-company carve-out
+ * for uncompanied actors in strict mode.
+ *
+ * The rule is exercised on its own (not against each model's full $rules)
+ * so unrelated pseudo-rules like License::limit_change don't crash the
+ * runner. A companion sanity file, FmcsCompanyRuleWiringTest, asserts
+ * every affected model's $rules array carries the rule.
+ */
+class FmcsCompanyValidatorTest extends TestCase
+{
+    public function test_rule_rejects_null_in_strict_fmcs_for_non_superuser()
+    {
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+        auth()->login(User::factory()->create());
+
+        $validator = Validator::make(['company_id' => null], ['company_id' => 'fmcs_company']);
+
+        $this->assertTrue($validator->fails());
+        $this->assertArrayHasKey('company_id', $validator->errors()->toArray());
+    }
+
+    public function test_rule_accepts_null_in_strict_fmcs_for_superuser()
+    {
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+        auth()->login(User::factory()->superuser()->create());
+
+        $validator = Validator::make(['company_id' => null], ['company_id' => 'fmcs_company']);
+
+        $this->assertFalse($validator->fails());
+    }
+
+    public function test_rule_accepts_null_when_floater_mode_enabled()
+    {
+        $this->settings->enableFloaterMode();
+        auth()->login(User::factory()->create());
+
+        $validator = Validator::make(['company_id' => null], ['company_id' => 'fmcs_company']);
+
+        $this->assertFalse($validator->fails());
+    }
+
+    public function test_rule_accepts_null_when_fmcs_off()
+    {
+        $this->settings->disableMultipleFullCompanySupport();
+        auth()->login(User::factory()->create());
+
+        $validator = Validator::make(['company_id' => null], ['company_id' => 'fmcs_company']);
+
+        $this->assertFalse($validator->fails());
+    }
+
+    public function test_rule_accepts_non_null_in_strict_fmcs_for_non_superuser()
+    {
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+        auth()->login(User::factory()->create());
+        $company = Company::factory()->create();
+
+        $validator = Validator::make(['company_id' => $company->id], ['company_id' => 'fmcs_company']);
+
+        $this->assertFalse($validator->fails());
+    }
+
+    public function test_rule_accepts_null_when_no_auth_context()
+    {
+        // CLI, seeders, and importers deliberately bypass, matching the
+        // SaveUserRequest cannot_make_floater gate's posture.
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+        auth()->logout();
+
+        $validator = Validator::make(['company_id' => null], ['company_id' => 'fmcs_company']);
+
+        $this->assertFalse($validator->fails());
+    }
+
+    public function test_rule_accepts_null_for_uncompanied_non_superuser_in_strict_mode()
+    {
+        // Regression guard for the pseudo-company workflow. Under
+        // Company::scopeCompanyablesDirectly in strict mode, actors
+        // with no company memberships are scoped to null-company rows
+        // (whereNull($column)). Null IS a valid company id for them.
+        // Forcing them to pick a non-null company would both lock them
+        // out of their normal workflow AND produce a row they wouldn't
+        // be able to see afterward.
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $actor = User::factory()->withoutCompany()->create();
+        $this->assertFalse($actor->companies()->exists(), 'test precondition: actor is uncompanied');
+        auth()->login($actor);
+
+        $validator = Validator::make(['company_id' => null], ['company_id' => 'fmcs_company']);
+
+        $this->assertFalse($validator->fails());
+    }
+
+    public function test_rule_still_rejects_null_for_companied_non_superuser_in_strict_mode()
+    {
+        // Reporter's #19192 case. A non-superuser WITH company
+        // memberships submitting a null company_id would land an
+        // invisible row. That must still fail.
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $company = Company::factory()->create();
+        $actor = $company->users()->save(User::factory()->create());
+        $this->assertTrue($actor->companies()->exists(), 'test precondition: actor has memberships');
+        auth()->login($actor);
+
+        $validator = Validator::make(['company_id' => null], ['company_id' => 'fmcs_company']);
+
+        $this->assertTrue($validator->fails());
+    }
+}
diff --git a/tests/Feature/Fmcs/FmcsStrictBulkAssetEditTest.php b/tests/Feature/Fmcs/FmcsStrictBulkAssetEditTest.php
new file mode 100644
index 0000000000..ac3ae915de
--- /dev/null
+++ b/tests/Feature/Fmcs/FmcsStrictBulkAssetEditTest.php
@@ -0,0 +1,116 @@
+<?php
+
+namespace Tests\Feature\Fmcs;
+
+use App\Models\Asset;
+use App\Models\Company;
+use App\Models\Setting;
+use App\Models\User;
+use Tests\TestCase;
+
+/**
+ * Regression coverage for GitHub issue #19192, part 4 of 4.
+ *
+ * BulkAssetsController::update() calls $asset->update($updateArray)
+ * per row, so the model-level fmcs_company rule reaches the bulk path
+ * via ValidatingTrait. These tests pin the behavior on both the
+ * "clearing Company should fail" and the "clearing Company is fine for
+ * uncompanied actors working in the pseudo-company namespace" paths,
+ * plus a sanity check that ordinary bulk edits touching only unrelated
+ * fields still succeed.
+ */
+class FmcsStrictBulkAssetEditTest extends TestCase
+{
+    public function test_clearing_company_is_rejected_for_companied_non_superuser()
+    {
+        // Locked in so a future refactor of the bulk controller cannot
+        // quietly bypass the gate.
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $company = Company::factory()->create();
+        $actor = $company->users()->save(User::factory()->editAssets()->create());
+        $target = Asset::factory()->create(['company_id' => $company->id]);
+
+        $this->actingAs($actor)
+            ->post(route('hardware/bulksave'), [
+                'ids' => [$target->id],
+                'company_id' => 'clear',
+                'bulk_actions' => 'edit',
+            ]);
+
+        $this->assertEquals($company->id, $target->fresh()->company_id, 'Row company should not have been cleared');
+    }
+
+    public function test_clearing_company_is_allowed_for_uncompanied_non_superuser()
+    {
+        // Uncompanied non-superusers work in the null pseudo-company
+        // namespace under strict mode. Bulk-clearing Company on rows
+        // they own is a legitimate operation for them and the gate
+        // steps aside.
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $actor = User::factory()->withoutCompany()->editAssets()->create();
+        $target = Asset::factory()->create(['company_id' => null]);
+
+        $this->actingAs($actor)
+            ->post(route('hardware/bulksave'), [
+                'ids' => [$target->id],
+                'company_id' => 'clear',
+                'bulk_actions' => 'edit',
+            ]);
+
+        $this->assertNull($target->fresh()->company_id);
+    }
+
+    public function test_editing_unrelated_field_still_works_for_companied_non_superuser()
+    {
+        // If the bulk edit doesn't touch Company at all, ValidatingTrait
+        // sees the existing non-null company_id on each row and passes.
+        // This is the "make sure we haven't broken ordinary bulk edits"
+        // sanity guard.
+        //
+        // Defensive Setting cache flush. Some upstream tests in the full
+        // MySQL sweep can leave the memoized Setting instance in a state
+        // where full_multiple_companies_support looks enabled at the
+        // moment auth loads but disabled by the time the fmcs_company
+        // validator reads it, or vice versa. The Support helper's update()
+        // clears the cache too, but only after both writes have landed.
+        // Clearing here first pins the pre-state so the two writes below
+        // are the only source of truth for this test's fmcs_company check.
+        Setting::$_cache = null;
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $company = Company::factory()->create();
+        $actor = $company->users()->save(User::factory()->editAssets()->create());
+        $target = Asset::factory()->create([
+            'company_id' => $company->id,
+            'notes' => 'before',
+        ]);
+
+        $response = $this->actingAs($actor)
+            ->post(route('hardware/bulksave'), [
+                'ids' => [$target->id],
+                'notes' => 'after',
+                'bulk_actions' => 'edit',
+            ]);
+
+        // Fail loudly if the controller redirected with per-row errors
+        // (the notes assertion below is a downstream symptom that hides
+        // the actual validation failure). BulkAssetsController flashes
+        // `bulk_asset_errors` (not `error`) when $asset->update() returns
+        // false because ValidatingTrait rejected the save. Pulling those
+        // errors into the assertion message turns any recurrence of the
+        // MySQL CI full-suite flake into a concrete diagnostic.
+        $bulkErrors = session('bulk_asset_errors');
+        $this->assertNull(
+            $bulkErrors,
+            'Bulk asset edit produced per-row validation errors: '.json_encode($bulkErrors, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT),
+        );
+
+        $this->assertEquals('after', $target->fresh()->notes);
+        $this->assertEquals($company->id, $target->fresh()->company_id);
+    }
+}
diff --git a/tests/Feature/Fmcs/FmcsStrictUsersHttpTest.php b/tests/Feature/Fmcs/FmcsStrictUsersHttpTest.php
new file mode 100644
index 0000000000..6b1d5a362c
--- /dev/null
+++ b/tests/Feature/Fmcs/FmcsStrictUsersHttpTest.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace Tests\Feature\Fmcs;
+
+use App\Models\User;
+use Tests\TestCase;
+
+/**
+ * Regression coverage for GitHub issue #19192, part 3 of 4.
+ *
+ * The User gate lives in SaveUserRequest, not on the model $rules
+ * array (Users don't run through ValidatingTrait the same way the other
+ * Companyable models do because pivot memberships live on company_user).
+ * Exercise the HTTP endpoints directly to lock in that strict FMCS
+ * rejects a blank company_ids for a non-superuser and accepts it for a
+ * superuser.
+ */
+class FmcsStrictUsersHttpTest extends TestCase
+{
+    public function test_strict_fmcs_rejects_empty_company_ids_for_non_superuser()
+    {
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $actor = User::factory()->create();
+        $username = 'strict-null-target-'.uniqid();
+
+        $this->actingAs($actor)
+            ->post(route('users.store'), [
+                'first_name' => 'Test',
+                'last_name' => 'User',
+                'username' => $username,
+                'email' => $username.'@example.com',
+                'password' => 'SomeGreatPassword-123',
+                'password_confirmation' => 'SomeGreatPassword-123',
+                // No company_ids submitted.
+            ])
+            ->assertSessionHasErrors('company_ids');
+
+        $this->assertDatabaseMissing('users', ['username' => $username]);
+    }
+
+    public function test_strict_fmcs_allows_empty_company_ids_for_superuser()
+    {
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $actor = User::factory()->superuser()->create();
+        $username = 'super-null-'.uniqid();
+
+        $this->actingAs($actor)
+            ->post(route('users.store'), [
+                'first_name' => 'Superuser-Created',
+                'last_name' => 'User',
+                'username' => $username,
+                'email' => $username.'@example.com',
+                'password' => 'SomeGreatPassword-123',
+                'password_confirmation' => 'SomeGreatPassword-123',
+            ])
+            ->assertSessionHasNoErrors('company_ids');
+    }
+}
diff --git a/tests/Feature/Users/Api/UpdateUserTest.php b/tests/Feature/Users/Api/UpdateUserTest.php
index b981608523..6d4cec721a 100644
--- a/tests/Feature/Users/Api/UpdateUserTest.php
+++ b/tests/Feature/Users/Api/UpdateUserTest.php
@@ -322,9 +322,16 @@ class UpdateUserTest extends TestCase
         $scoped_user_in_companyB = User::factory()->forCompany($companyB->id)->create();
         $scoped_user_in_no_company = User::factory()->withoutCompany()->create();
 
+        // Each PATCH carries company_ids so the strict-FMCS gate added
+        // for #19192 doesn't hijack the authorization assertion — the
+        // test's intent is to verify company-scoped authorization, not
+        // to exercise the empty-pivot gate.
+        $bodyA = ['company_ids' => [$companyA->id]];
+        $bodyB = ['company_ids' => [$companyB->id]];
+
         // Admin for Company A should allow updating user from Company A
         $this->actingAsForApi($adminA)
-            ->patchJson(route('api.users.update', $scoped_user_in_companyA))
+            ->patchJson(route('api.users.update', $scoped_user_in_companyA), $bodyA)
             ->assertOk()
             ->assertStatus(200)
             ->assertStatusMessageIs('success')
@@ -332,7 +339,7 @@ class UpdateUserTest extends TestCase
 
         // Admin for Company A should get denied updating user from Company B
         $this->actingAsForApi($adminA)
-            ->patchJson(route('api.users.update', $scoped_user_in_companyB))
+            ->patchJson(route('api.users.update', $scoped_user_in_companyB), $bodyB)
             ->assertOk()
             ->assertStatus(200)
             ->assertStatusMessageIs('error')
@@ -340,7 +347,7 @@ class UpdateUserTest extends TestCase
 
         // Admin for Company A should get denied updating user without a company
         $this->actingAsForApi($adminA)
-            ->patchJson(route('api.users.update', $scoped_user_in_no_company))
+            ->patchJson(route('api.users.update', $scoped_user_in_no_company), $bodyA)
             ->assertOk()
             ->assertStatus(200)
             ->assertStatusMessageIs('error')
@@ -348,7 +355,7 @@ class UpdateUserTest extends TestCase
 
         // Admin for Company B should allow updating user from Company B
         $this->actingAsForApi($adminB)
-            ->patchJson(route('api.users.update', $scoped_user_in_companyB))
+            ->patchJson(route('api.users.update', $scoped_user_in_companyB), $bodyB)
             ->assertOk()
             ->assertStatus(200)
             ->assertStatusMessageIs('success')
@@ -356,7 +363,7 @@ class UpdateUserTest extends TestCase
 
         // Admin for Company B should get denied updating user from Company A
         $this->actingAsForApi($adminB)
-            ->patchJson(route('api.users.update', $scoped_user_in_companyA))
+            ->patchJson(route('api.users.update', $scoped_user_in_companyA), $bodyA)
             ->assertOk()
             ->assertStatus(200)
             ->assertStatusMessageIs('error')
@@ -364,13 +371,17 @@ class UpdateUserTest extends TestCase
 
         // Admin for Company B should get denied updating user without a company
         $this->actingAsForApi($adminB)
-            ->patchJson(route('api.users.update', $scoped_user_in_no_company))
+            ->patchJson(route('api.users.update', $scoped_user_in_no_company), $bodyB)
             ->assertOk()
             ->assertStatus(200)
             ->assertStatusMessageIs('error')
             ->json();
 
-        // Admin without a company should allow updating user without a company
+        // Admin without a company should allow updating user without
+        // a company. Under strict FMCS mode uncompanied users operate
+        // in the null pseudo-company namespace (Company scoping shows
+        // them null-company rows); the #19192 gate steps aside for
+        // them so this normal workflow keeps working.
         $this->actingAsForApi($adminNoCompany)
             ->patchJson(route('api.users.update', $scoped_user_in_no_company))
             ->assertOk()
diff --git a/tests/Feature/Users/Ui/FloaterModeGateTest.php b/tests/Feature/Users/Ui/FloaterModeGateTest.php
index 0c5da490a6..cf6c0d3d39 100644
--- a/tests/Feature/Users/Ui/FloaterModeGateTest.php
+++ b/tests/Feature/Users/Ui/FloaterModeGateTest.php
@@ -72,8 +72,17 @@ class FloaterModeGateTest extends TestCase
         $this->assertEmpty($target->fresh()->companies->pluck('id')->all(), 'Superuser is trusted to grant floater status');
     }
 
-    public function test_guard_does_not_apply_when_floater_mode_is_off()
+    public function test_strict_mode_now_blocks_non_superuser_from_clearing_company_ids()
     {
+        // Prior to #19192 this test documented that the #19200 floater
+        // gate skipped strict mode entirely (canGrantFloaterStatus()
+        // returns true when floaters are off, so no check fired). The
+        // reporter's #19192 case demonstrated that same permissive
+        // behavior lets a non-superuser end up with an empty pivot in
+        // strict FMCS mode, making the target instantly invisible to
+        // its creator's scope. The gate now also fires in strict mode
+        // for non-superusers, so a non-superuser cannot clear a user's
+        // company memberships to empty either.
         $this->settings->enableMultipleFullCompanySupport();
         $this->settings->disableFloaterMode();
 
@@ -86,7 +95,7 @@ class FloaterModeGateTest extends TestCase
                 'username' => $actor->username,
                 'company_ids' => [],
             ])
-            ->assertSessionDoesntHaveErrors('company_ids');
+            ->assertSessionHasErrors('company_ids');
     }
 
     public function test_non_superuser_cannot_bulk_clear_companies_in_floater_mode()
@@ -109,6 +118,56 @@ class FloaterModeGateTest extends TestCase
         $this->assertNotEmpty($victim->fresh()->companies);
     }
 
+    public function test_non_superuser_cannot_bulk_clear_companies_in_strict_fmcs_mode()
+    {
+        // #19192 companion to the floater-mode test above: strict FMCS
+        // (floaters OFF) also blocks a non-superuser from bulk-clearing
+        // pivot memberships, because doing so would make every targeted
+        // user instantly invisible to the acting admin's own scope.
+        // Pre-fix, BulkUsersController's only gate was canGrantFloaterStatus,
+        // which returns true in strict mode and let the clear proceed.
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $company = Company::factory()->create();
+        $actor = $company->users()->save(User::factory()->editUsers()->create());
+        $victim = $company->users()->save(User::factory()->create());
+
+        $this->actingAs($actor)
+            ->post(route('users/bulkeditsave'), [
+                'ids' => [$victim->id => '1'],
+                'null_company_ids' => '1',
+            ])
+            ->assertRedirect()
+            ->assertSessionHas('error');
+
+        $this->assertContains($company->id, $victim->fresh()->companies->pluck('id')->all(), 'Bulk clear in strict mode should be refused');
+        $this->assertNotEmpty($victim->fresh()->companies);
+    }
+
+    public function test_strict_fmcs_bulk_clear_gate_does_not_fire_for_superuser()
+    {
+        // Superusers see everything (their scope reaches null-pivot
+        // rows), so leaving pivots empty is a deliberate action for
+        // them, not the visibility trap that motivates #19192. The
+        // gate must not fire — whether the pivot ends up actually
+        // cleared is a separate concern owned by the bulk-clear
+        // controller flow, tested elsewhere.
+        $this->settings->enableMultipleFullCompanySupport();
+        $this->settings->disableFloaterMode();
+
+        $company = Company::factory()->create();
+        $actor = User::factory()->superuser()->create();
+        $victim = $company->users()->save(User::factory()->create());
+
+        $this->actingAs($actor)
+            ->post(route('users/bulkeditsave'), [
+                'ids' => [$victim->id => '1'],
+                'null_company_ids' => '1',
+            ])
+            ->assertSessionMissing('error');
+    }
+
     public function test_non_superuser_cannot_create_a_new_user_with_no_companies_in_floater_mode()
     {
         // Covers the web POST path — SaveUserRequest's withValidator fires on