Selectable voids should be atomic navigation points - Plate

Problem

In /examples/embeds, placing the caret at the end of the first paragraph and pressing ArrowRight skipped the embed void block and landed in the following paragraph.

That is wrong for a selectable block void. The void is not text content to traverse by default, but it is still a selectable document position.

Root Cause

The traversal layer filtered out every path inside a void when voids: false.

That made sense for hiding void internals, but it also removed the void's atomic selection point. Editor.after, Editor.before, and editor.move() then saw no position between the previous paragraph and the following paragraph.

Fix

Keep the contract in core Editor.positions:

default traversal exposes selectable void/read-only ancestors as one atomic start point
default traversal skips the descendants inside that atomic element
voids: true enters the actual children

Do not special-case the embeds example or React keydown. The public traversal contract is the owner.

Tests

Add a core query-contract test before browser work:

Editor.positions(editor, { at: [] }) returns one point for a selectable void
Editor.positions(editor, { at: [], voids: true }) returns the actual internal child offsets
Editor.after, Editor.before, and editor.move() visit the void before the following block

Then add browser proof for /examples/embeds:

select DOM at [0,0]@177
press ArrowRight once and assert [1,0]@0
press ArrowRight again and assert [2,0]@0

2026-05-03 Inline Void Character Movement Update

The same rule applies to inline voids during unit: 'character' movement. /examples/mentions exposed the sharper failure: ArrowRight from before a mention skipped the mention and consumed the first character after it, while ArrowLeft from after the mention consumed the previous character before it.

The fix stayed in core traversal:

keep void/read-only descendants hidden by default
expose the atomic element itself as the next character stop
map a second forward movement from that atom to the next text segment start
map a second reverse movement from that atom to the previous text segment end

The regression test should cover both sides of at least two inline voids:

[1,0]@end ArrowRight -> [1,1,0]@0
[1,1,0]@0 ArrowRight -> [1,2]@0
[1,2]@0 ArrowLeft -> [1,1,0]@0
[1,1,0]@0 ArrowLeft -> [1,0]@end
[1,2]@end ArrowRight -> [1,3,0]@0
[1,3,0]@0 ArrowRight -> [1,4]@0
[1,4]@0 ArrowLeft -> [1,3,0]@0
[1,3,0]@0 ArrowLeft -> [1,2]@end

Do not collapse the two stops back into one. Skipping from the preceding text straight to the following text makes the mention impossible to select with plain arrow-key navigation.

2026-05-06 Block Void Delete And Enter Update

Atomic selection is not enough if model-owned Backspace and Enter still fall through to generic text transforms.

Two browser rows locked the block-void command contract in /examples/images:

Backspace from an empty paragraph immediately after a block void removes that empty paragraph and selects the void instead of deleting the void.
Enter on a clicked selected block void inserts an editable paragraph after the void, matching the behavior users expect from an arrow-key selected void.

Keep this in the model-owned mutation path, not in the image example. The React command layer owns the browser intent because it sees the selected void and can repair the model selection after the structural operation.

Prevention

When keyboard navigation skips a void, test Editor.positions first. If core traversal does not expose the void atomically, React keydown fixes are papering over the wrong layer.

For inline void regressions, also test Editor.after and Editor.before with unit: 'character'; default unit: 'offset' can pass while human ArrowLeft and ArrowRight still overshoot.

For destructive block-void regressions, replay both user paths: Backspace from the adjacent empty block and Enter from a clicked selected void. The first protects deletion ordering; the second protects click-selected and arrow-selected void parity.