Accept a visible autocomplete ghost on Tab before list indent

[janglad]

Before
tab both accepted suggestion and moves bullet

Screen.Recording.2026-10-06.at.18.32.26.mov

After
accepts suggestion first, then bullet

Screen.Recording.2026-10-06.at.18.32.09.mov

Summary

Tab under a visible autocomplete ghost nested the list item instead of accepting the ghost. The default keymap (Tab → pen.indent) ran before the inline-completion check, so it won the key in any list item that could nest. Fixes WEB-4235.

 handleFieldEditorKeyDown
   history / select-all shortcuts
   handleTableCellKey
+  if Tab (no shift) and ghost visible
+    accept ghost, return
   dispatchKeymapEvent            # Tab → pen.indent, Shift-Tab → pen.outdent
   if Tab or Shift-Tab
     if ghost visible
       accept ghost, return
     if no shift
       autocomplete.request({ explicit: true })

• Shift-Tab still reaches the keymap first, so outdent works under a ghost.
• Tab with no ghost still nests the list item.
• spec/rules/commands.md gains K5 for this precedence; the new tests claim it in scripts/rule-coverage-claimed.txt.

Evidence

• Before: K5: accepts a visible inline completion instead of nesting a list item fails

  second bullet "Hello", ghost " world" visible, press Tab
  AssertionError: expected 'Hello' to be 'Hello world'
  

  After: the same test passes, with indent unchanged at 0

  pen-dom    135 files, 908 tests passed
  pen-react  165 files, 531 tests passed
  

• K5: outdents a list item on Shift-Tab while an inline completion is visible is a regression guard; it passes before and after.

• Not checked in a browser or in the input composer.

Merge Danger

Door: two-way

Reverting restores the old key order. Nothing is persisted and no public API changes.

Blast Radius: keyboard

• Applies to both input backends (contenteditable and EditContext), since both route through handleFieldEditorKeyDown.
• A host keymap binding on Tab can no longer win the key while a ghost is visible.
• If a ghost is visible but accepting it fails, Tab in a list item now does nothing where it used to nest.
• Consumers see this only after a release and a version bump of @input/pen-dom.

---

Note

Medium Risk
Keyboard routing change in the shared field-editor path: host keymap Tab bindings cannot win while a ghost is visible, and failed accept may leave Tab inert in lists where indent used to run.

Overview
Tab precedence for inline autocomplete (K5) — When a visible autocomplete ghost is shown, unmodified Tab now accepts the suggestion before the default keymap runs, so pen.indent no longer nests list items under the hint. Shift-Tab is unchanged: it still hits the keymap first so outdent works with a ghost visible; Tab with no ghost still indents/nests as before.

Implementation is in handleFieldEditorKeyDown (keyHandling.ts): an early Tab branch plus shared acceptVisibleInlineCompletion / isTabOrShiftTab helpers. Spec rule K5 documents the behavior; new React tests cover list-item accept and Shift-Tab outdent; @input/pen-dom gets a patch changeset.

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[janglad]

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[noudadrichem]

Nice!