appendHtmlPreviewBaseHref detected the head tag with /<head[^>]*>/i,
which also matches <header ...>. For a fragment with no <head> that
opens with <header> - a common shape in agent-generated report pages -
the <base> element was injected after the <header> opening tag instead
of being prepended, so relative assets appearing before that point
(e.g. a leading <img>) resolved without the base and failed to load in
the sandboxed iframe.
Use the word-boundary-safe /<head(?:\s[^>]*)?>/i that the sibling
appendHtmlPreviewScrollRestoration already uses, keeping the two
injectors consistent.
* feat(artifacts): inline editing for text artifacts in the panel
Add a PUT /api/threads/{id}/artifacts/{path} endpoint that atomically
replaces an existing UTF-8 text file under /mnt/user-data/outputs after
verifying its SHA-256 revision. Active runs conflict (409); binary,
symlink, oversized, and non-output paths are rejected.
Frontend: edit/save/discard buttons, draft state with conflict detection,
CodeEditor onChange/onSave, loader SHA-256 from ETag, i18n, beforeunload guard.
Backend: PUT endpoint with thread reservation, atomic temp-file replacement,
sandbox sync for non-mounted providers, rollback on failure, ETag on GET.
Tests: 8 backend + 1 blocking-IO + 3 frontend test files.
* fix(artifacts): scope replacement permissions and release sandboxes
---------
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
