🛡️ Sentinel: [CRITICAL] Fix Path Traversal in File Download API

[thirdeyenation]

🚨 Severity: CRITICAL
💡 Vulnerability: The DownloadFile endpoint in api/download_work_dir_file.py used file_info.get_file_info without properly validating the user-provided path parameter against the application's base directory limits.
🎯 Impact: An attacker could use ../ directory traversal payloads to download any readable file from the host operating system outside of the intended workspace directory (e.g., system configuration files or secrets).
🔧 Fix: Added a definitive security boundary check using helpers.files.is_in_base_dir() after resolving the absolute path in the DownloadFile endpoint. If the resolved path escapes the base directory bounds, the API safely rejects the request with a ValueError.
✅ Verification: Verified by running unit tests. The fix prevents directory traversal payloads like ../../../etc/passwd from successfully returning file contents. Recorded the learning in .jules/sentinel.md.

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PR created automatically by Jules for task 17354534009067564141 started by @thirdeyenation

[google-labs-jules]

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