Issue 4637 Reproduction Plan

Goal

Determine whether GitHub issue #4637 is reproducible on the current Plate site or current repo behavior, and identify whether it is a real editor bug or old CSS/config-specific behavior.

Source of Truth

• Issue: https://github.com/udecode/plate/issues/4637
• Title: Spaces do overflow, instead of getting moved to the next line
• Reported version: Plate 21.3.2, Slate React 0.95.0
• Reported browser: Chrome
• Reproduction URL: https://platejs.org/

Phases

Phase	Status	Notes
Read issue and extract repro details	complete	Steps and environment captured
Search prior learnings and likely code paths	complete	Current editor wrapper inspected
Attempt live reproduction	complete	Repro attempted against platejs.org/ in Chrome
Compare with current implementation	complete	Current CSS and browser behavior align
Summarize validity	in_progress	Final verdict pending user handoff

Key Repro Steps

1. Write a word.
2. Put the cursor in the middle.
3. Insert spaces until the right half wraps.
4. Keep inserting spaces.
5. Observe whether spaces wrap or visually overflow past the editor width.

Initial Hypotheses

• The behavior was caused by old editor CSS around white-space, wrapping, or overflow-wrap.
• The issue may be specific to older Slate/Plate rendering semantics and no longer reproduce on current versions.
• The live site may still show it if the editor content area allows preserved spaces without a wrapping rule.

Findings

• Current site editor wrapper already includes overflow-x-hidden whitespace-pre-wrap break-words in apps/www/src/registry/ui/editor.tsx.
• The obvious CSS failure mode suggested in the issue comments is not present in current apps/www.
• Live Chrome repro on 2026-03-29 against https://platejs.org/:
  • placed the caret in the middle of Welcome
  • inserted 80 spaces
  • heading wrapped onto multiple lines
  • no horizontal overflow was observed
  • editable.scrollWidth === editable.clientWidth
  • caret remained inside the editor width
• Browser screenshot saved at /Users/zbeyens/.browser-use/tmp/issue-4637-current-site.png.
• This does not prove the original 2025 report was wrong; it does show the issue is not reproducible on the current site surface.

Progress Log

• Loaded task, learnings-researcher, planning-with-files, and reproduce-bug.
• Deleted the prior #4535 investigation plan artifact at the user's request.
• Fetched the full GitHub issue with comments.
• Loaded browser-use once the issue was confirmed to be browser-facing.
• Inspected apps/www/src/registry/ui/editor.tsx and confirmed current wrapping classes are present.
• Ran a live browser repro on platejs.org with 80 inserted spaces in the middle of a word and captured screenshot + DOM measurements.

Verification

• No code edits planned unless the user later asks for a fix.
• Browser verification is required for this issue.
• Browser verification completed in Chrome against the live reproduction URL.