Safety policy and render versions
Safety boundary: stripHtml removes script/style/image tags and comments; safeHref allows only https:, http:, mailto: and # anchors; every label is passed through escapeHtml for SVG plan text. The input preview only ever writes textContent, never user HTML.
While typing quickly or switching templates, createRenderGate assigns a monotonic version per render and slower older results are discarded; commitRender keeps the last successful tree on failure and flags it stale — explicitly NOT a result of the current input. Empty input takes the empty-state branch with no error stack.
Each policy has fixed-vector assertions in tests/acceptance.test.mjs, reproducible with npm run test:smoke.