What shipped, and whenWhat shipped, and when

Provider objects now carry their own configuration and events

Preview surfaces render the template's background colour

Image and video blocks take an explicit height

Dialogs no longer get clipped when the host page traps fixed positioning

The header's Viewport, Dark mode and Preview controls now hold their position for the whole session

The sidebar rail collapses again after a palette entry is clicked

Clicking a block in the sidebar palette now inserts it directly below the selected block, and scrolls it into view

Fix: bare merge-tag tokens in loaded and imported content now behave as merge tags.

Fix: the unrenderable-block marker could emit a stray -- inside its HTML comment.

Fix: the media library could not mount at all on 0.27.0 — in either mount mode.

Comments become a bring-your-own provider, and the editor learns who is using it.

Work around a Chromium bug (verified in Chromium 140–151, including stable Chrome) where pressing End or Home shortly after triple-clicking inside a text block armed a native scroll: the next typed character smooth-scrolled the canvas to its very bottom (End) or top (Home), dragging the caret out of view. Rich-text blocks now handle plain End/Home through Selection.modify — identical visual-line caret movement, without arming the bug. Shift+End/Home selection extension keeps its native behavior.

Decode entity-encoded merge-tag attribute values

Stop writing redundant attributes into serialized merge tags

Fix merge tags whose values contain < or > (custom mergeTags.syntax)

Add an alignment option to the button block (#536).

Fix onChange never firing for the first content change after the dirty flag resets (#522).

Add justify to the paragraph toolbar's alignment group

Add a11y.text-justified — flags justified body copy in paragraph blocks

Add resolvePreview — a hook that resolves the template for preview surfaces using your own backend, so previews can show real data instead of tokens.

Fix dialogs ignoring the theme config option (#487). The saved-blocks browser, the save-block dialog and the test-email dialog rendered in the SDK's default colours inside an otherwise themed editor.

Add MergeTag.sample — an example value that previews render in place of the tag, so a preview reads like a delivered email instead of a list of field names.

Add bring-your-own test emails — let users mail themselves the template they're editing, sent through your own infrastructure.