V3 deterministic HTML cleanup and conversion capability pack. By-value connector composition (service_kind=cli, no separate ingredient): one local HTML Tidy CLI ingredient exposes readiness plus fixed HTML formatting and XHTML conversion operations. Fixed-function and reproducible: the executor materializes the source HTML and owns the throwaway output directory, while tidy writes fixed result files that are captured as result.file_ref. Write-tier but approval=never: tidy writes only to an engine-managed output dir, exposes no arbitrary flags or config file, and never streams source bytes through op-step values. Requires the tidy binary on PATH (Debian/Ubuntu: apt install tidy; macOS: brew install tidy-html5). Local and no-egress.