F1: pc.title (untrusted cross-user page title) was interpolated raw into the
markdown export heading. Reusing escapeAttr alone (the prompt sink's XML-attribute
sanitizer, strips < > ") is insufficient here because the sink is MARKDOWN: link
/image syntax survives, so a title like  or [phish](http://evil)
injects a remote image / clickable link into the downloaded .md disguised as a
trusted system annotation. Add markdownHeadingSafe() = escapeAttr() + backslash-
escape [ and ] (disables both [text](url) and ; a bare (url) is inert).
F2: cover the title branch — a title that collapses to empty via escapeAttr falls
to the bare heading (no ("")), and a link/image-injection title is neutralized
(non-vacuous vs the escapeAttr-only version).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The #274 page_changed marker lived only in the ephemeral system prompt, so the
diff the agent saw was invisible in the chat export/history, and the note was
too weak — the agent still overwrote the user's manual edits with a full-page
replace.
- Persist the diff the agent saw as metadata.pageChanged on the assistant row
(flushAssistant), threaded into all five flush call sites in stream(). Model
replay (rowToUiMessage/rowParts) reads only metadata.parts, so the sibling
never re-injects the note into the model context on later turns.
- Render the persisted diff as a labelled block (en/ru) before the message body
in the server-side Markdown export (chat-markdown.util.ts).
- Strengthen PAGE_CHANGED_NOTE: mandate a fresh getPage re-read and targeted
edits (editPageText/patchNode/insertNode/deleteNode) instead of a whole-page
replace, and never revert or overwrite the user's edits.
Tests: prompt, export and service specs updated; 114 pass, tsc clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
agent_coder
claude_code