Bugs

• Pattern Overrides Experiment: Block toolbar items duplicated when duplicating a pattern

  New paragraph can be added by hitting enter at end of existing paragraph that has editable attributes, but the new paragraph can't be edited. (fix: Pattern Overrides: Add template-lock: all to pattern inner blocks to prevent deletion/insertion #57661)

  A user can multi-select two non-adjacent paragraphs that have overrides and delete any 'locked' blocks between them. (fix: Pattern Overrides: Add template-lock: all to pattern inner blocks to prevent deletion/insertion #57661)

  Fix the white background when editing a pattern in the post editor (fixed by Patterns: Add black border back when editing synced pattern in the post editor #57631)

  If you delete the content from a paragraph with editable attrib, it looks empty, which is what user may want, but saving and reloading brings back content from the original pattern, which in other cases may also be what user wants 🤔. (update: unable to reproduce this in recent testing)

  The contentOnly UI for editing overriden blocks currently shows the text align tool on the toolbar, but this isn't supported (it can be changed but the changes aren't saved). (PR: Remove text align control for paragraph, heading, and button in contentOnly editing mode #57906)

  Detaching patterns loses the overrides #58122 (PR: Fix losing overrides after detaching patterns #58164)
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Follow Ups

• Use the solution in #57036 for template only mode (see this comment) - (PR: Remove template-only mode from editor and edit-post packages #57700)

  Explore highlighting editable blocks - (PR - Outline editable blocks that are within a content-locked container #57901)
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Suggested enhancements/explorations

• Consider how future features like shuffling might work

  Reconsider using Ids to bind blocks, the data stored in the pattern block should be more readable/interpretable - draft PR using name instead of id

  When a pattern is redesigned, there's a chance a user will modify blocks/attributes in a way that they become disconnected from the instances of a pattern (e.g. renaming the block to something different). Explore ways to prevent/warn a user about these risks.

  Change the override attribute name to content - (PR - #58596)

  Patterns: change info to "Overrides enabled"

  Look into storing the block name as metadata in the overrides data (PR - #58715)
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Block specific issues

Image Block

Supported attributes: url, id, title, alt

• Adding an image that has a caption set in the media library displays the caption, even when the original pattern has been designed to hide captions. (it disappears after a refresh though)

  Pattern Overrides: Image block doesn't render on frontend when it's saved as a placeholder in a pattern

  Caption is not supported as a block bindings attribute, but can be edited in the UI (when toggled on in the original pattern) (PR: #58916)

  Pattern Overrides: Image id attribute can mismatch the image url attribute, which results in buggy behavior

  Alt and title are supported attributes, but are not editable in the UI (they're hidden by content only mode) (PR: #58998)

  Link is not supported as a block bindings attribute, but can be edited in the UI (PR: Disable overriding links of images inside pattern instances #58660)
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Button Block

Supported attributes: text, url

• Link (url) attribute is supported, but related attributes linkTarget and rel are not supported as block bindings attributes, but are still editable in the UI (PR: Support button's link settings for Pattern Overrides #58587)
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Heading block

Supported attributes: content

• Heading level isn't supported, could/should it be?
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Paragraph block

Supported attributes: content
No known issues

General Bugs

• Lock icons display in List View for a pattern's inner blocks (even though the blocks are still content editable)

  Pattern override: individual binding attributes are saved in the pattern markup and don't auto-update

  While testing Pattern Overrides, I Found conflict with Live Collaboration and offline persistence mode

  Nesting one overridden pattern within another causes nested pattern to crash - (PR: Patterns: Prevent exception if a pattern with overrides is nested in another pattern #58359)
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Code quality

• Explore better ways to show/hide block UI that doesn't involve hard-coding references to 'core/block' in the codebase, AKA address where blockEditingMode doesn't quite work for the pattern block (see Patterns: edit source pattern in focus mode in post and site editors #57036 (comment))
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Future

• Features like pattern overrides and block bindings have limited control over block UI

  As part of the block binding API, users can denote connections to different sources (e.g. custom fields, other post values, custom data sources). To declare a pattern override, the user also defines connections. Given they're separate UIs, some thought needs to go into what happens when a user attempts to connect a pattern override on a block that's already connected to a custom field—should it overwrite it, should it be prevented, how is the user made aware of the risk/outcome.

  At the moment the API will work for one block at a time. A solution will be needed for lists, galleries or anything that requires a series/array of bound blocks. (see Add new mode to contentOnly locking to allow insertion of new inner blocks #52018 for similar challenges with contentOnly mode). One solution explored here [PoC] Patterns: try partial syncing of inner blocks #56348

  Some exploration might be need around how block deprecations will work (i.e. if a block attribute name changes)

  If a user completely deletes a source pattern, they will potentially lose content everywhere the pattern is used. Are there ways to restore this content, maybe offering a flow similar to block recovery?
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.