The serializer treated only DIV/P as blocks: a formatting element
directly under the editable root (a bolded segment of an undivided
line is a top-level <b>) became a separate PLAIN block, losing both
the formatting and the paragraph structure. Top-level inline runs now
accumulate into one paragraph, and style-based formatting (Firefox's
font-weight/font-style spans) maps back to markers.
Attachments: the upload allowlist rejected everything but a handful of
types with a console-only 415. The logic inverts — raster images get
derivatives, script carriers (svg/html/js/xml...) are refused, and any
other file stores as a download chip. Upload failures now show in the
composer, and toolbar buttons keep the contenteditable selection on
click (mousedown.prevent).
LeoVasanko
49bdedd938