Keep the separating comma out of trailing comments when injecting MCP servers (#977)

* Keep the separating comma out of trailing comments when injecting MCP servers

* Skip single-quoted strings when masking comments so a // inside a JSON5 string is not read as one

* Cut the comma-fix comment blocks to one line where they earn it

---------

Co-authored-by: Pushpak Chhajed <pushpak1300@gmail.com>

Author: sulimanbenhalim

src/Install/Mcp/FileWriter.php

@@ -150,8 +150,14 @@ protected function injectIntoExistingConfigKey(string $content, array $matches):
         $commaPosition = $this->findCommaInsertionPoint($content, $openBracePos, $closeBracePos);
 
         if ($commaPosition !== -1) {
-            $newContent = substr_replace($content, ',', $commaPosition, 0);
-            $newContent = substr_replace($newContent, $serversJson, $commaPosition + 1, 0);
+            // Anything non-blank before the brace is a trailing comment: comma goes ahead of it, servers after it.
+            if (trim(substr($content, $commaPosition, $closeBracePos - $commaPosition)) === '') {
+                $newContent = substr_replace($content, ',', $commaPosition, 0);
+                $newContent = substr_replace($newContent, $serversJson, $commaPosition + 1, 0);
+            } else {
+                $newContent = substr_replace($content, $serversJson, $closeBracePos, 0);
+                $newContent = substr_replace($newContent, ',', $commaPosition, 0);
+            }
         } else {
             $newContent = substr_replace($content, $serversJson, $closeBracePos, 0);
         }
@@ -289,24 +295,24 @@ protected function needsCommaBeforeClosingBrace(string $content, int $openBraceP
 
     protected function findCommaInsertionPoint(string $content, int $openBracePos, int $closeBracePos): int
     {
+        // Strings are matched only to skip them; comments become equal-length spaces so offsets still line up.
+        $masked = preg_replace_callback(
+            '/"(?:\\\\.|[^"\\\\])*"|\'(?:\\\\.|[^\'\\\\])*\'|(\/\/[^\r\n]*)|(\/\*[\s\S]*?\*\/)/',
+            fn (array $match): string => ($match[1] ?? '') !== '' || ($match[2] ?? '') !== ''
+                ? str_repeat(' ', strlen($match[0]))
+                : $match[0],
+            $content
+        ) ?? $content;
+
         // Work backwards from closing brace to find last meaningful character
         for ($i = $closeBracePos - 1; $i > $openBracePos; $i--) {
-            $char = $content[$i];
+            $char = $masked[$i];
 
             // Skip whitespace and newlines
             if (in_array($char, [' ', "\t", "\n", "\r"], true)) {
                 continue;
             }
 
-            // Skip comments (simple approach - if we hit //, skip to start of line)
-            if ($i > 0 && $content[$i - 1] === '/' && $char === '/') {
-                // Find start of this line
-                $lineStart = strrpos($content, "\n", $i - strlen($content)) ?: 0;
-                $i = $lineStart;
-
-                continue;
-            }
-
             // Found last meaningful character, comma goes after it
             if ($char !== ',') {
                 return $i + 1;

tests/Unit/Install/Mcp/FileWriterTest.php

@@ -451,6 +451,78 @@
         );
 });
 
+test('adds the comma outside a trailing comment in the servers object', function (): void {
+    $writtenContent = '';
+
+    $contentWithTrailingComment = <<<'JSON5'
+    {
+      "mcpServers": {
+        "context7": {
+          "command": "npx"
+        } // docs lookup
+      }
+    }
+    JSON5;
+
+    mockFileOperations(
+        fileExists: true,
+        content: $contentWithTrailingComment,
+        capturedContent: $writtenContent
+    );
+
+    File::shouldReceive('size')->andReturn(200);
+
+    $result = (new FileWriter('/path/to/mcp.json'))
+        ->addServerConfig('boost', [
+            'command' => 'php',
+            'args' => ['artisan', 'boost:mcp'],
+        ])
+        ->save();
+
+    $withoutComments = preg_replace('/\/\/[^\n]*/', '', $writtenContent);
+
+    expect($result)->toBeTrue()
+        ->and(json_decode((string) $withoutComments, true))->not->toBeNull()
+        ->and($writtenContent)->toContain(
+            '"boost"', // New server added
+            '"context7"', // Existing server preserved
+            '// docs lookup' // Comment preserved
+        );
+});
+
+test('does not read a // inside a single-quoted string as a comment', function (): void {
+    $writtenContent = '';
+
+    $singleQuotedUrl = <<<'JSON5'
+    {
+      'mcpServers': {
+        'remote': { 'url': 'https://example.test/sse' }
+      }
+    }
+    JSON5;
+
+    mockFileOperations(
+        fileExists: true,
+        content: $singleQuotedUrl,
+        capturedContent: $writtenContent
+    );
+
+    File::shouldReceive('size')->andReturn(200);
+
+    $result = (new FileWriter('/path/to/mcp.json'))
+        ->addServerConfig('boost', [
+            'command' => 'php',
+            'args' => ['artisan', 'boost:mcp'],
+        ])
+        ->save();
+
+    expect($result)->toBeTrue()
+        ->and($writtenContent)->toContain(
+            "'url': 'https://example.test/sse'", // URL survives untouched
+            '"boost"' // New server added
+        );
+});
+
 test('updates JSON5 file with only single-quoted strings', function (): void {
     $writtenContent = '';
     $singleQuotedJson5 = <<<'JSON5'