Review fixes on top of the DOMPurify mXSS hardening:
- Remove `USE_PROFILES: { html: true }` from the sanitize-html.js config. DOMPurify
treats USE_PROFILES and ALLOWED_TAGS/ALLOWED_ATTR as mutually exclusive — with a
profile set it resets the allow-lists to the full HTML profile and silently ignores
the curated lists, so the tight markdown-only allowlist was dead config (still
XSS-safe via FORBID + core, but far broader than intended: <button>/<input>/
<details>/<audio>/<select>/<label> all survived). Dropping USE_PROFILES puts the
curated ALLOWED_TAGS/ALLOWED_ATTR back in force; FORBID_TAGS/FORBID_ATTR stay as
defense-in-depth and DOMPurify keeps its default safe-URI handling.
- Rewrite test/markdown-sanitizer.test.ts to run in the default node environment with
an in-test jsdom window instead of a per-file jsdom environment. That environment
externalizes node:fs/node:path under vite, so the suite failed to load in isolation
("No such built-in module: node:") and only survived the full CI run because an
earlier node-env test happened to pre-cache node:fs — order-dependent and fragile.
The rewrite is order-robust and adds an "allowlist is actually enforced" block
(non-markdown tags must be dropped) that fails if USE_PROFILES is reintroduced.
Verified: 25/25 tests pass standalone under config/vitest.ci.config.ts; tsc, lint,
format:check, check:frontend-syntax, check:public-assets, and npm run build all clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The previous _sanitizeHtml was a denylist over agent/transcript markdown
rendered via innerHTML; it missed style attributes and the svg/math mXSS
namespaces — e.g. <svg><style><img src=x onerror=alert(1)></style></svg>
re-serialized into a live <img onerror>.
Vendor DOMPurify 3.4.8 (allowlist) following the existing marked.min.js
vendor pattern (same-origin, CSP script-src 'self'; not in package.json so
no lockfile drift). New sanitize-html.js wires a hardened allowlist config
(FORBID style/svg/math/script/iframe/object/embed/form; no data attrs);
app.js _sanitizeHtml delegates to it with a fail-closed escape-all fallback.
index.html loads dompurify -> sanitize-html -> app.js (defer); build.mjs
minifies + content-hashes sanitize-html.js.
Test: test/markdown-sanitizer.test.ts (jsdom, real shipping artifacts) —
mXSS payloads neutralized + legit markdown preserved.
Claude (Codeman maintainer)