🛡️ Sentinel: [HIGH] Fix Zip Slip path traversal vulnerability in skills import

.jules/sentinel.md

@@ -0,0 +1,4 @@
+## 2025-05-29 - Zip Slip in Skills Import
+**Vulnerability:** Unsafe extraction of ZIP archives allowing path traversal via z.extractall(target) without checking member paths.
+**Learning:** Archives can contain relative paths like ../ to write files outside the intended extraction directory.
+**Prevention:** Always iterate through z.namelist(), resolve absolute paths, and use Path.is_relative_to() to ensure containment within the target directory before extracting.

helpers/skills_import.py

@@ -94,6 +94,10 @@ def _unzip_to_temp_dir(zip_path: Path) -> Path:
     target.mkdir(parents=True, exist_ok=True)
 
     with zipfile.ZipFile(zip_path, "r") as z:
+        for member in z.namelist():
+            member_path = (target / member).resolve()
+            if not member_path.is_relative_to(target.resolve()):
+                raise ValueError(f"Unsafe path in archive: {member}")
         z.extractall(target)
 
     # If zip contains a single top-level folder, treat that as the root