feat(vikon): add atomicSwap to FilesystemTask for crash-safe updates

app/Containers/VikonIntegration/Tasks/FilesystemTask.php

@@ -64,6 +64,64 @@ class FilesystemTask
         return File::deleteDirectory($source);
     }
 
+    public function atomicSwap(
+        string $newEntryPath,
+        string $currentEntryPath,
+        string $baseDir,
+        int $moduleId
+    ): bool {
+        if (!$this->isPathSafe($currentEntryPath, $baseDir)) {
+            return false;
+        }
+
+        if (!File::exists($newEntryPath)) {
+            return false;
+        }
+
+        $isFile = is_file($newEntryPath);
+        $newPostfix = $currentEntryPath . '_new';
+        $oldPostfix = $currentEntryPath . '_old';
+
+        if (File::exists($currentEntryPath)) {
+            // Step 1: Remove stale _new if exists
+            if (File::exists($newPostfix)) {
+                $isFile ? File::delete($newPostfix) : File::deleteDirectory($newPostfix);
+            }
+
+            // Step 2: Move new → _new
+            if (!$this->moveEntry($newEntryPath, $newPostfix, $isFile)) {
+                return false;
+            }
+
+            // Step 3: Remove stale _old if exists
+            if (File::exists($oldPostfix)) {
+                $isFile ? File::delete($oldPostfix) : File::deleteDirectory($oldPostfix);
+            }
+
+            // Step 4: Move current → _old
+            if (!$this->moveEntry($currentEntryPath, $oldPostfix, $isFile)) {
+                return false;
+            }
+
+            // Step 5: Move _new → current
+            return $this->moveEntry($newPostfix, $currentEntryPath, $isFile);
+        }
+
+        // Entry doesn't exist — move directly
+        return $this->moveEntry($newEntryPath, $currentEntryPath, $isFile);
+    }
+
+    private function moveEntry(string $source, string $dest, bool $isFile): bool
+    {
+        if ($isFile) {
+            $parent = dirname($dest);
+            if (!File::isDirectory($parent)) {
+                File::makeDirectory($parent, 0755, true, true);
+            }
+        }
+        return rename($source, $dest);
+    }
+
     public function validateFileTypes(string $directory): array
     {
         $allowed = [

app/Containers/VikonIntegration/Tests/Unit/FilesystemTaskTest.php

@@ -0,0 +1,85 @@
+<?php
+
+namespace App\Containers\VikonIntegration\Tests\Unit;
+
+use App\Containers\VikonIntegration\Tasks\FilesystemTask;
+use App\Ship\Tests\TestCase;
+use Illuminate\Support\Facades\File;
+
+class FilesystemTaskTest extends TestCase
+{
+    private string $tempDir;
+    private FilesystemTask $fs;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->tempDir = sys_get_temp_dir() . '/vikon_test_' . uniqid();
+        File::makeDirectory($this->tempDir, 0755, true, true);
+        $this->fs = new FilesystemTask();
+    }
+
+    protected function tearDown(): void
+    {
+        File::deleteDirectory($this->tempDir);
+        parent::tearDown();
+    }
+
+    public function test_atomic_swap_replaces_existing_entry(): void
+    {
+        $base = $this->tempDir . '/module';
+        File::makeDirectory($base . '/common', 0755, true, true);
+
+        file_put_contents($base . '/common/index.php', '<?php echo "old";');
+
+        $newDir = $this->tempDir . '/extracted/common';
+        File::makeDirectory($newDir, 0755, true, true);
+        file_put_contents($newDir . '/index.php', '<?php echo "new";');
+
+        $result = $this->fs->atomicSwap(
+            $newDir,
+            $base . '/common',
+            $base,
+            1
+        );
+
+        $this->assertTrue($result);
+        $this->assertFileExists($base . '/common/index.php');
+        $this->assertStringContainsString('new', file_get_contents($base . '/common/index.php'));
+        $this->assertDirectoryExists($base . '/common_old');
+        $this->assertDirectoryDoesNotExist($base . '/common_new');
+    }
+
+    public function test_atomic_swap_creates_new_entry_when_not_exists(): void
+    {
+        $base = $this->tempDir . '/module';
+        File::makeDirectory($base, 0755, true, true);
+
+        $newDir = $this->tempDir . '/extracted/assets';
+        File::makeDirectory($newDir, 0755, true, true);
+        file_put_contents($newDir . '/style.css', 'body {}');
+
+        $result = $this->fs->atomicSwap(
+            $newDir,
+            $base . '/assets',
+            $base,
+            1
+        );
+
+        $this->assertTrue($result);
+        $this->assertFileExists($base . '/assets/style.css');
+        $this->assertDirectoryDoesNotExist($base . '/assets_old');
+    }
+
+    public function test_atomic_swap_returns_false_on_path_traversal(): void
+    {
+        $result = $this->fs->atomicSwap(
+            '/etc/passwd',
+            $this->tempDir . '/module/etc',
+            $this->tempDir . '/module',
+            1
+        );
+
+        $this->assertFalse($result);
+    }
+}