fix: wire is_hard_drop_enabled + drop_score_threshold settings into Classifier filter chain

Settings::register_classifier_filters() registers priority-5 callbacks on
cf7stg_classifier_thresholds and cf7stg_hard_drop_rules so the UI options
actually influence Classifier behaviour. Called from Plugin::boot(). User
filters at priority 10 override these defaults as expected. Adds 4 tests
covering the wired behaviour and override priority. Also adds dry_run_drop?
to MessageFormatter::build() @param docblock.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

includes/class-message-formatter.php

@@ -24,7 +24,8 @@ final class MessageFormatter
      *   reason:string,
      *   ip:string,
      *   user_agent:string,
-     *   is_retro:bool
+     *   is_retro:bool,
+     *   dry_run_drop?:bool
      * } $ctx
      *
      * @return array{text:string,reply_markup:array|null}

includes/class-plugin.php

@@ -43,6 +43,9 @@ final class Plugin
 
     public function boot(): void
     {
+        // Inject silent-drop options into Classifier filter chain
+        Settings::register_classifier_filters();
+
         // Register runtime hooks
         Dispatcher::register_hooks();
         (new CF7Source())->register();

includes/class-settings.php

@@ -171,4 +171,27 @@ final class Settings
             'reset_at'       => $today,
         ];
     }
+
+    /**
+     * Register default callbacks that inject silent-drop options into the
+     * Classifier's filter chain. Runs at plugin boot. User filters at the
+     * default priority (10) override these (priority 5).
+     */
+    public static function register_classifier_filters(): void
+    {
+        add_filter('cf7stg_classifier_thresholds', static function ($thresholds) {
+            if (is_array($thresholds)) {
+                $thresholds['drop'] = self::get_drop_score_threshold();
+            }
+            return $thresholds;
+        }, 5);
+
+        add_filter('cf7stg_hard_drop_rules', static function ($rules) {
+            if (is_array($rules) && !self::is_hard_drop_enabled()) {
+                $rules['short_latin_name']   = false;
+                $rules['placeholder_fields'] = false;
+            }
+            return $rules;
+        }, 5);
+    }
 }

tests/ClassifierDropTest.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 namespace Cf7stg\Tests;
 
 use Cf7stg\Classifier;
+use Cf7stg\Settings;
 
 final class ClassifierDropTest extends Cf7stgTestCase
 {
@@ -283,4 +284,55 @@ final class ClassifierDropTest extends Cf7stgTestCase
         $r = Classifier::classify($fields, ['reason' => 'Akismet']);
         self::assertSame('drop', $r['label']);
     }
+
+    public function test_hard_drop_disabled_via_settings_skips_drop(): void
+    {
+        Settings::set_hard_drop_enabled(false);
+        Settings::register_classifier_filters();
+        $fields = require __DIR__ . '/fixtures/spam-screenshot-1.php';
+        $r = Classifier::classify($fields, ['reason' => 'Akismet']);
+        // With hard-rule disabled, screenshot-1 has no positive signals AND score isn't ≤ -5
+        // (placeholders by themselves give no score penalty), so label should NOT be 'drop'.
+        self::assertNotSame('drop', $r['label']);
+    }
+
+    public function test_drop_score_threshold_from_settings_applied(): void
+    {
+        Settings::set_drop_score_threshold(-3);
+        Settings::register_classifier_filters();
+        // URL gives -3 score, no positive signals, no hard-rule trigger.
+        // With threshold lowered to -3, this should fire score-based drop.
+        $fields = ['msg' => 'http://x.com'];
+        $r = Classifier::classify($fields, ['reason' => 'Akismet']);
+        self::assertSame('drop', $r['label']);
+    }
+
+    public function test_settings_threshold_can_be_overridden_by_user_filter(): void
+    {
+        Settings::set_drop_score_threshold(-3);
+        Settings::register_classifier_filters();
+        // User filter at priority 10 should override Settings default at priority 5.
+        add_filter('cf7stg_classifier_thresholds', static function ($t) {
+            $t['drop'] = -10;
+            return $t;
+        }, 10);
+        $fields = ['msg' => 'http://x.com']; // score = -3
+        $r = Classifier::classify($fields, ['reason' => 'Akismet']);
+        // -3 is NOT ≤ -10, so no drop
+        self::assertNotSame('drop', $r['label']);
+    }
+
+    public function test_filter_disables_placeholder_fields_rule(): void
+    {
+        add_filter('cf7stg_hard_drop_rules', static function ($rules) {
+            $rules['placeholder_fields'] = false;
+            return $rules;
+        });
+        // Form WITHOUT name field — digit-only values are valid placeholders (^[A-Za-z0-9]{1,2}$)
+        // but FieldDetector::find_name rejects them (has digits), so short_latin_name cannot fire.
+        // With placeholder_fields rule also disabled → no hard-rule fires → no drop.
+        $fields = ['a' => '11', 'b' => '22', 'c' => '33', 'd' => '44'];
+        $r = Classifier::classify($fields, ['reason' => 'Akismet']);
+        self::assertNotSame('drop', $r['label']);
+    }
 }