Implement merge conflict handling and restore module directory

composer.json

@@ -1,5 +1,6 @@
 {
   "name": "saucebase/module-installer",
+  "version": "1.0.1",
   "description": "Custom Composer installer for Sauce Base modules (type: saucebase-module). Installs to Modules/<Name> with configurable base dir.",
   "type": "composer-plugin",
   "license": "MIT",
@@ -12,8 +13,8 @@
   "require": {
     "php": "^8.4",
     "composer-plugin-api": "^2.0",
-    "symfony/finder": "^8.0",
-    "symfony/process": "^8.0"
+    "symfony/finder": "^7.0 || ^8.0",
+    "symfony/process": "^7.0 || ^8.0"
   },
   "require-dev": {
     "composer/composer": "^2.0",

src/Installer.php

@@ -183,6 +183,20 @@ protected function getUpdateStrategy(): string
         return $strategy;
     }
 
+    /**
+     * Restore a stashed module directory back to its original install path.
+     * If the original path was re-created (e.g. by a partial update), the stash is discarded.
+     */
+    protected function restoreStash(string $stashPath, PackageInterface $package): void
+    {
+        $originalPath = $this->getInstallPath($package);
+        if (! is_dir($originalPath)) {
+            (new SymfonyFilesystem)->rename($stashPath, $originalPath);
+        } else {
+            (new Filesystem)->removeDirectory($stashPath);
+        }
+    }
+
     /**
      * Rename the module directory to a temp location and return the temp path.
      * Returns null if the directory does not exist.
@@ -257,7 +271,7 @@ protected function mergeStash(string $stash, string $base, string $install): voi
                 $this->io->writeError("  <warning>Merge conflict in $rel — conflict markers inserted</warning>");
             }
 
-            rename($merged, $newFile);
+            (new SymfonyFilesystem)->rename($merged, $newFile, true);
         }
     }
 
@@ -306,9 +320,9 @@ function () use ($target, $stashPath, $basePath) {
                     (new Filesystem)->removeDirectory($basePath);
                 }
             },
-            function (\Throwable $e) use ($stashPath, $basePath) {
+            function (\Throwable $e) use ($stashPath, $basePath, $initial) {
                 if ($stashPath !== null) {
-                    (new Filesystem)->removeDirectory($stashPath);
+                    $this->restoreStash($stashPath, $initial);
                 }
                 if ($basePath !== null) {
                     (new Filesystem)->removeDirectory($basePath);

tests/ModuleInstallerTest.php

@@ -53,6 +53,11 @@ public function callMergeStash(string $stash, string $base, string $install): vo
     {
         parent::mergeStash($stash, $base, $install);
     }
+
+    public function callRestoreStash(string $stashPath, PackageInterface $package): void
+    {
+        parent::restoreStash($stashPath, $package);
+    }
 }
 
 final class ModuleInstallerTest extends TestCase
@@ -379,4 +384,70 @@ public function test_merge_stash_respects_upstream_deletions(): void
         $fs->remove($base);
         $fs->remove($install);
     }
+
+    // -------------------------------------------------------------------------
+    // restoreStash
+    // -------------------------------------------------------------------------
+
+    public function test_restore_stash_renames_stash_back_when_original_path_missing(): void
+    {
+        $io = $this->createStub(IOInterface::class);
+        $composer = $this->createStub(Composer::class);
+
+        $root = new RootPackage('root/app', '1.0.0.0', '1.0.0');
+        $root->setExtra(['module-dir' => sys_get_temp_dir()]);
+        $composer->method('getPackage')->willReturn($root);
+
+        $installer = new TestableInstaller($io, $composer);
+
+        $stash = sys_get_temp_dir().'/module-stash-restore-test-'.uniqid('', true);
+        mkdir($stash);
+        file_put_contents($stash.'/custom.php', '<?php // user file');
+
+        $pkg = new Package('saucebase/test-module', '1.0.0.0', '1.0.0');
+
+        // The original install path does not exist (was cleared during update)
+        $originalPath = $installer->getInstallPath($pkg);
+        $this->assertDirectoryDoesNotExist($originalPath);
+
+        $installer->callRestoreStash($stash, $pkg);
+
+        $this->assertDirectoryDoesNotExist($stash);
+        $this->assertDirectoryExists($originalPath);
+        $this->assertFileExists($originalPath.'/custom.php');
+
+        (new Filesystem)->remove($originalPath);
+    }
+
+    public function test_restore_stash_discards_stash_when_original_path_already_exists(): void
+    {
+        $io = $this->createStub(IOInterface::class);
+        $composer = $this->createStub(Composer::class);
+
+        $root = new RootPackage('root/app', '1.0.0.0', '1.0.0');
+        $root->setExtra(['module-dir' => sys_get_temp_dir()]);
+        $composer->method('getPackage')->willReturn($root);
+
+        $installer = new TestableInstaller($io, $composer);
+
+        $pkg = new Package('saucebase/already-there', '1.0.0.0', '1.0.0');
+
+        // Pre-create the original path (partial update left it behind)
+        $originalPath = $installer->getInstallPath($pkg);
+        mkdir($originalPath, 0755, true);
+        file_put_contents($originalPath.'/partial.php', 'partial');
+
+        $stash = sys_get_temp_dir().'/module-stash-discard-test-'.uniqid('', true);
+        mkdir($stash);
+        file_put_contents($stash.'/custom.php', '<?php // user file');
+
+        $installer->callRestoreStash($stash, $pkg);
+
+        // Stash was discarded, original path (with partial content) remains
+        $this->assertDirectoryDoesNotExist($stash);
+        $this->assertDirectoryExists($originalPath);
+        $this->assertFileExists($originalPath.'/partial.php');
+
+        (new Filesystem)->remove($originalPath);
+    }
 }