The --root DIR flag was already fully implemented in the codebase.
All 25 tests pass (12 unit + 13 integration tests).
Acceptance criteria verified:
- Path traversal rejected with -32602
- Absolute paths rejected when --root is set
- HTTPS URLs bypass the check
- Symlink escapes detected via canonicalize
- Startup validation for root directory
Co-Authored-By: Claude Code <noreply@anthropic.com>