FiberLab Guardian inspects candidate code changes, validates module contracts, prepares an isolated integration workspace, and runs permitted quality checks.

It is designed as a project-level code inspection and integration assistant. It is not a hardened security sandbox.

The integration engine currently implements the following protections:

• Rejects absolute candidate paths.
• Rejects candidate paths containing .. traversal components.
• Checks candidate path components for symbolic links.
• Resolves candidate paths and verifies that they remain within the candidate root.
• Checks the destination path for an existing symbolic link before path resolution.
• Creates integration workspaces separately from the original project.
• Excludes Git metadata, virtual environments, caches, and other configured directories from workspace copies.

Candidate path validation, containment checks, and file copying are separate filesystem operations.

A concurrent local process could modify a validated candidate or destination path between these operations. This may allow filesystem access outside the intended roots.

Status: Known and accepted limitation for the current project scope.

Severity: Medium.

Mitigation: Guardian should only operate on trusted local workspaces. Stronger descriptor-relative filesystem operations and race-resistant copying may be considered in a future security-hardening phase.

The integration workspace is a separate project copy, not an operating-system security boundary.

Subprocess timeouts limit execution duration but do not prevent filesystem access, network access, or other potentially unsafe operations.

Guardian must not execute untrusted pull-request code in the normal inspection workflow.

• Download candidate files from the exact pull-request commit.
• Perform static inspection before integration.
• Do not execute untrusted pull-request code.
• Disable quality-check execution for untrusted PR candidates.
• Require human review before accepting or merging changes.

Potential future improvements include:

• Race-resistant filesystem operations.
• OS-level sandboxing for untrusted code execution.
• More comprehensive filesystem permission checks.
• Additional security-focused automated tests.

Guardian reports are automated engineering assessments. A passing report does not guarantee that code is free from vulnerabilities, constitute security certification, or approve a pull request for merging.

Human review remains mandatory.