fix: unread/read disucssion bug

composer.json

@@ -60,10 +60,18 @@
         "flarum/flags": "*"
     },
     "scripts": {
+        "test": [
+            "@php -r \"echo 'Available test commands:'.PHP_EOL.'  composer test:setup'.PHP_EOL.'  composer test:integration'.PHP_EOL;\""
+        ],
+        "test:setup": "@php tests/integration/setup.php",
+        "test:integration": "phpunit -c tests/phpunit.integration.xml",
         "analyse:phpstan": "phpstan analyse",
         "clear-cache:phpstan": "phpstan clear-result-cache"
     },
     "scripts-descriptions": {
+        "test": "Show available test commands",
+        "test:setup": "Set up integration test environment",
+        "test:integration": "Run integration tests",
         "analyse:phpstan": "Run static analysis"
     },
     "minimum-stability": "beta",

src/Api/Commands/SplitDiscussionHandler.php

@@ -13,6 +13,7 @@
 namespace FoF\Split\Api\Commands;
 
 use Flarum\Discussion\Discussion;
+use Flarum\Discussion\UserState;
 use Flarum\Extension\ExtensionManager;
 use Flarum\Post\Post;
 use Flarum\Post\PostRepository;
@@ -83,6 +84,9 @@ public function handle(SplitDiscussion $command)
             new DiscussionWasSplit($command->actor, $affectedPosts, $originalDiscussion, $discussion)
         );
 
+        $originalDiscussion = $this->refreshDiscussion($originalDiscussion);
+        $this->clampReadStates($originalDiscussion);
+
         return $discussion;
     }
 
@@ -156,6 +160,14 @@ protected function refreshDiscussion(Discussion $discussion)
         return Discussion::find($discussion->id);
     }
 
+    protected function clampReadStates(Discussion $discussion): void
+    {
+        UserState::query()
+            ->where('discussion_id', $discussion->id)
+            ->where('last_read_post_number', '>', $discussion->last_post_number)
+            ->update(['last_read_post_number' => $discussion->last_post_number]);
+    }
+
     /**
      * Sets the tags for the new discussion based on the old one.
      *

tests/integration/api/SplitReadStateTest.php

@@ -0,0 +1,165 @@
+<?php
+
+namespace FoF\Split\Tests\integration\api;
+
+use Flarum\Discussion\Discussion;
+use Flarum\Discussion\UserState;
+use Flarum\Post\Post;
+use Flarum\Testing\integration\TestCase;
+use PHPUnit\Framework\Attributes\Test;
+
+class SplitReadStateTest extends TestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->extension('fof-split');
+
+        $this->prepareDatabase([
+            'users' => [
+                [
+                    'id' => 1,
+                    'username' => 'admin',
+                    'email' => 'admin@example.test',
+                    'is_email_confirmed' => true,
+                    'password' => 'password',
+                    'joined_at' => '2026-01-01 00:00:00',
+                ],
+                [
+                    'id' => 2,
+                    'username' => 'moderator',
+                    'email' => 'moderator@example.test',
+                    'is_email_confirmed' => true,
+                    'password' => 'password',
+                    'joined_at' => '2026-01-01 00:00:00',
+                ],
+            ],
+            'group_user' => [
+                ['user_id' => 1, 'group_id' => 1],
+                ['user_id' => 2, 'group_id' => 4],
+            ],
+            'discussions' => [
+                [
+                    'id' => 1,
+                    'title' => 'Source Discussion',
+                    'slug' => 'source-discussion',
+                    'user_id' => 1,
+                    'comment_count' => 5,
+                    'participant_count' => 1,
+                    'created_at' => '2026-01-01 00:00:00',
+                    'last_posted_at' => '2026-01-01 00:04:00',
+                    'last_post_number' => 5,
+                    'first_post_id' => 10,
+                    'last_post_id' => 14,
+                ],
+            ],
+            'posts' => [
+                $this->commentPost(10, 1, 1, 1, '2026-01-01 00:00:00', '<p>Post 1</p>'),
+                $this->commentPost(11, 1, 1, 2, '2026-01-01 00:01:00', '<p>Post 2</p>'),
+                $this->commentPost(12, 1, 1, 3, '2026-01-01 00:02:00', '<p>Post 3</p>'),
+                $this->commentPost(13, 1, 1, 4, '2026-01-01 00:03:00', '<p>Post 4</p>'),
+                $this->commentPost(14, 1, 1, 5, '2026-01-01 00:04:00', '<p>Post 5</p>'),
+            ],
+            'discussion_user' => [
+                [
+                    'discussion_id' => 1,
+                    'user_id' => 1,
+                    'last_read_post_number' => 5,
+                    'last_read_at' => '2026-01-01 00:04:00',
+                ],
+            ],
+        ]);
+    }
+
+    #[Test]
+    public function it_clamps_stale_read_state_after_split_and_keeps_the_source_unread_after_a_new_reply(): void
+    {
+        $splitResponse = $this->send(
+            $this->request('POST', '/api/split', [
+                'authenticatedAs' => 1,
+                'json' => [
+                    'title' => 'Split Child',
+                    'start_post_id' => 12,
+                    'end_post_number' => 5,
+                ],
+            ])
+        );
+
+        $this->assertSame(200, $splitResponse->getStatusCode());
+
+        /** @var Discussion $sourceDiscussion */
+        $sourceDiscussion = Discussion::query()->findOrFail(1);
+        /** @var UserState $userState */
+        $userState = UserState::query()
+            ->where('discussion_id', 1)
+            ->where('user_id', 1)
+            ->firstOrFail();
+
+        $this->assertSame(2, $sourceDiscussion->last_post_number);
+        $this->assertSame(2, $userState->last_read_post_number);
+
+        $replyResponse = $this->send(
+            $this->request('POST', '/api/posts', [
+                'authenticatedAs' => 2,
+                'json' => [
+                    'data' => [
+                        'type' => 'posts',
+                        'attributes' => [
+                            'content' => 'Moderator reply after split',
+                        ],
+                        'relationships' => [
+                            'discussion' => [
+                                'data' => [
+                                    'type' => 'discussions',
+                                    'id' => '1',
+                                ],
+                            ],
+                        ],
+                    ],
+                ],
+            ])
+        );
+
+        $this->assertSame(201, $replyResponse->getStatusCode());
+
+        $sourceDiscussion->refresh();
+        $userState = UserState::query()
+            ->where('discussion_id', 1)
+            ->where('user_id', 1)
+            ->firstOrFail();
+
+        $this->assertSame(4, $sourceDiscussion->last_post_number);
+        $this->assertSame(2, $userState->last_read_post_number);
+
+        $showResponse = $this->send(
+            $this->request('GET', '/api/discussions/1', ['authenticatedAs' => 1])
+        );
+
+        $this->assertSame(200, $showResponse->getStatusCode());
+
+        $showJson = json_decode($showResponse->getBody()->getContents(), true);
+
+        $this->assertSame(4, $showJson['data']['attributes']['lastPostNumber']);
+        $this->assertSame(2, $showJson['data']['attributes']['lastReadPostNumber']);
+    }
+
+    protected function commentPost(
+        int $id,
+        int $discussionId,
+        int $userId,
+        int $number,
+        string $createdAt,
+        string $content
+    ): array {
+        return [
+            'id' => $id,
+            'discussion_id' => $discussionId,
+            'user_id' => $userId,
+            'type' => 'comment',
+            'number' => $number,
+            'created_at' => $createdAt,
+            'content' => $content,
+        ];
+    }
+}

tests/integration/setup.php

@@ -0,0 +1,9 @@
+<?php
+
+use Flarum\Testing\integration\Setup\SetupScript;
+
+require __DIR__.'/../../vendor/autoload.php';
+
+$setup = new SetupScript();
+
+$setup->run();

tests/phpunit.integration.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
+         bootstrap="integration/setup.php"
+         colors="true">
+    <testsuites>
+        <testsuite name="Integration">
+            <directory suffix="Test.php">./integration</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>