* fix(frontend): restore sanitization in custom streamdown rehype chains
Streamdown 2.5 replaces its entire default rehype chain
[rehype-raw, rehype-sanitize, rehype-harden] with whatever array the
caller passes via the rehypePlugins prop. Every custom chain in this
repo therefore rendered LLM/stored markdown without any sanitization:
- Artifact markdown previews (markdown-preview-plugins.ts +
artifact-file-detail.tsx) parse raw HTML via rehypeRaw, so a
generated .md artifact could inject <style>/<iframe>/on* handlers
into the workspace DOM (stored XSS; only javascript: anchors were
blocked by the ArtifactLink component).
- The memory settings summary (memory-settings-page.tsx) spread the
shared preset without component overrides, so a hostile
<a href="javascript:..."> in stored memory content rendered as a
clickable anchor.
Fix strategy:
- Add rehype-sanitize (already resolved in the lockfile via streamdown)
as a direct dependency and re-insert a [rehypeSanitize, schema] step
in the shared preset (core/streamdown/plugins.ts). It runs after
rehypeRaw (raw HTML must be parsed into hast before it can be
cleaned) and before rehypeKatex/rehypeSlug (their output is trusted
and would otherwise be filtered or clobbered) - the same
raw -> sanitize -> math ordering streamdown itself uses.
- The schema extends rehype-sanitize's GitHub-style defaultSchema (the
base of streamdown's own sanitize schema) so legitimate authored
artifact HTML (tables, details, images, alignment/size attributes)
keeps working while script/iframe/style, on* handlers and
non-allow-listed URL schemes (javascript:, data:, ...) are dropped.
The only extensions are tel: hrefs and the math-inline/math-display
class markers remark-math emits and rehype-katex detects.
- Position rehypeSlug after the sanitize step in the artifact chain so
sanitize's id clobbering (id="x" -> id="user-content-x") cannot break
the heading anchors it creates.
- Pass a: createMarkdownLinkComponent() on the memory settings page as
defense in depth, matching the chat rendering path.
Unit tests feed a hostile payload (<a href="javascript:...">,
<img onerror>, <script>, <iframe>, <style>, ontoggle) through both
render paths and assert no executable/clickable equivalent survives,
plus regression guards for heading anchors, legitimate HTML and KaTeX
math rendering.
* fix(frontend): keep the sanitize clobber prefix on heading anchors; minimal lockfile
Review follow-ups on the sanitization change:
- Heading anchors: rehypeScopedSlug replaces rehype-slug in the artifact
chain. It runs after the sanitize step (so raw-HTML headings are also
anchored) but keeps rehype-sanitize's user-content- id prefix — an
untrusted heading like "## current" cannot mint an unprefixed
id="current" (the DOM-clobbering shape the sanitizer guards against).
In-page fragment links are translated to the prefixed anchors so they
still resolve; external URLs, bare "#", already-prefixed fragments and
sanitize-prefixed raw-HTML ids are left untouched.
- Lockfile: regenerated as a minimal diff — only the two direct-dependency
importer entries (rehype-sanitize, github-slugger for the scoped slug)
are added; the libc platform selectors on the 64 native package records
are preserved byte-for-byte instead of being dropped by lockfile
normalization.
Full frontend suite: 1034 tests passing; tsc and prettier clean.
* style: reorder github-slugger import ahead of the hast type import
* test(e2e): expect the clobber-prefixed heading anchor in artifact preview
The scoped slug plugin gives generated heading ids rehype-sanitize's
user-content- prefix and translates fragment links to match, so the
anchor-scroll test must locate the prefixed id.
* fix(frontend): reset the scoped slugger per tree; keep footnote anchors single-prefixed
Review follow-ups:
- The scoped slug attacher holds one GithubSlugger, but streamdown
caches the unified processor by plugin name, so the instance survived
across parses and repeated renders of the same heading grew -1/-2
suffixes (the artifact-anchor e2e could not find the id on re-render).
The transformer now resets the slugger per tree, as rehype-slug does;
a regression test renders identical artifact markdown twice.
- remark-rehype emits GFM footnote anchors already clobber-prefixed
(user-content-fn-1); the sanitize step prefixed those ids again while
their hrefs stayed single-prefixed, breaking footnote navigation in
every chain built on the shared preset. A new rehypeClobberFragments
step runs right after sanitize: double-prefixed ids are normalized
back to one prefix, and unprefixed fragment hrefs are translated to
the prefixed form (already-prefixed and external links untouched).
The artifact slug now inserts after this step; covered by a footnote
regression test on the shared render path.
Unit suite 1036 passing; artifact-preview e2e verified locally
(9/9, including the heading-anchor scroll test).
