The regenerated summary block embeds raw user-message text and was passed
as the *replacement* argument to String.prototype.replace, where $-sequences
($&, $$, $`, $') are special. A user message containing $& re-injected the
entire matched block (duplicating the summary markers) and $$ collapsed to $,
silently corrupting the persisted session summary. buildSummarySection only
escapes newlines and backticks, not $.
Fix: use function replacers (() => summaryBlock) at both rewrite sites so the
replacement text is treated literally. Adds an end-to-end regression test.
Co-authored-by: bymle <229636660+bymle@users.noreply.github.com>
e7e38cd508