Empty-Block Line-Break IME Proof Plan

Goal

Prove whether the empty-block line-break placeholder path can safely drop FEFF in legacy Slate.

Current Result

Blocked on harness quality.

What Was Tried

• added a jsdom-based composition test on an empty editor
• manually removed the FEFF text node from the line-break placeholder while keeping
• dispatched native CompositionEvent start/update/end on the editable root

Why It Is Blocked

The event never reached the real Editable composition path in a trustworthy way.

That means the test cannot distinguish between:

• a genuinely broken no-FEFF IME path
• and jsdom/react test limitations around contenteditable composition events

In other words:

• this is not a valid proof seam

Honest Next Step

Do not widen legacy policy from this harness.

The next proof needs:

• a browser-capable IME harness
• or a narrower runtime seam closer to the real composition pipeline that still counts as meaningful evidence

Until then:

• legacy keeps FEFF on the empty-block start-of-block line-break path
• future v2 policy stays open, not proven