From ca97688fd1ba508cc893a016d0f7b24867c147aa Mon Sep 17 00:00:00 2001
From: winterdrive <90021888+winterdrive@users.noreply.github.com>
Date: Thu, 9 Jul 2026 07:09:02 +0800
Subject: [PATCH] fix(mcp): guard files iteration in validate_json_structure
 against undefined

Groups without a "files" key (a valid, optional field) hit the else
branch's `for...of g.files`, throwing "undefined is not iterable".
That TypeError was swallowed by the outer catch and reported back to
the AI agent as a misleading "JSON parse error" for otherwise valid
JSON.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
---
 mcp-server/src/server.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mcp-server/src/server.ts b/mcp-server/src/server.ts
index 212bccd..982ac03 100644
--- a/mcp-server/src/server.ts
+++ b/mcp-server/src/server.ts
@@ -597,7 +597,7 @@ export class VirtualTabsMCPServer {
                 if (!g.name) { errors.push(`Group[${i}] missing "name".`); }
                 if (g.files !== undefined && !Array.isArray(g.files)) {
                   errors.push(`Group "${g.name ?? i}" has invalid "files" (expected array or undefined).`);
-                } else {
+                } else if (Array.isArray(g.files)) {
                   for (const f of g.files) {
                     if (path.isAbsolute(f)) {
                       errors.push(`Group "${g.name}": absolute path detected: "${f}". Must be workspace-relative.`);