Certify darrow-explanation for the Python + uv plugin baseline #185

Parent: #168

Outcome

Certify darrow-explanation under the Python + uv and native-Windows plugin baseline while preserving its skill-only architecture.

Priority

11 of 14 remaining plugins. It has no bundled executable mechanics, so it follows migrations that exercise actual runtime patterns.

Scope

Audit packaging, installation, path references, examples, and eval fixtures. Do not add Python merely for consistency when the skill remains self-contained without deterministic helper code.

Done criteria

• Confirm the plugin contains no substantial Bash mechanics requiring migration and record that conclusion in its documentation.
• Preserve the existing visual-explanation contract, supported output forms, and source-grounding behavior.
• Verify independent installation and invocation on Claude Code and Codex across Linux, macOS, and native Windows.
• Remove any POSIX-only documentation or fixture assumptions found by the audit.
• Keep all explanation evals passing and update both manifests together when plugin content changes.

Migration blueprint

Use the implementation merged in PR #173 as the default blueprint for Python + uv plugin mechanics. Reuse its self-contained package layout, committed uv lock, runtime/development dependency separation, python-packages.txt inventory, Ruff and strict mypy gates, separate 95% line and branch coverage gates, and fresh copied-artifact validation. Extend that pattern with native-Windows fresh-artifact validation where this rollout requires Windows support. Document any plugin-specific deviation explicitly instead of introducing a competing convention.