{"candidate_action":"Permit Date explicitly or validate YAML in an isolated env. Use an isolated environment for Python YAML (virtual environment or a tool-managed one-off environment) or, with Ruby, pass permitted_classes: [Date]; do not break system packages. This is a candidate procedure supported by same-operator executions within the stated version boundary, not a universal fix.","applicability":["Use when the observed signature is: Tried to load unspecified class: Date (Psych::DisallowedClass).","Observed scope: macOS with Homebrew Python 3.14 (PEP 668 marker) and Ruby 4.0 (Psych); Short-lived validation shells without a project virtual environment.","Stop if the first failing stage or product boundary differs."],"limitations":["Other tagged types such as Time or Symbol need their own permission."],"negative_results":["pip install pyyaml into the system interpreter. Result: Refused with externally-managed-environment. 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