Draft.js: caret/selection control before URL append (must land on new line after body)

[Trace824]

Summary

When appending a URL after the compose body, the caret/selection is often not at the end of the Draft.js editor. The URL inserts mid-sentence, producing mangled published text (URL spliced into the body).

Repro

• Context: x.com Draft.js compose with multi-line intent: opinion body, then site URL on its own line.
• Steps:
  1. Type or insert body text.
  2. Without explicitly moving caret to end / new line, append https://… via insert_text or type_text.
  3. Inspect draft (and published status if sent).
• Observed: URL lands mid-sentence, e.g. body text interrupted by https://full-selfbrowsing.com/ then remaining words.
• Example of mangled public post pattern: URL embedded inside the sentence rather than on its own trailing line.

Code pointers (verified against /workspace/FSB)

• extension/content/actions.js — placeCaretAtEnd (~L3492); draft_fast_path append branch collapses range to end (~L2979–2985); resolveEditableTarget (~L2107) for nested contenteditable under tweetTextarea_0.
• extension/background.js — cdpInsertText does not guarantee Draft selection-at-end before Input.insertText (~L20055+).
• extension/site-guides/social/twitter.js — compose selectors (tweetTextarea_0, tweet buttons).

Proposed fix

Before any append insert into Draft.js compose: resolve the editable root, place caret at end (Range collapse false), optionally insert a leading \n when the last char is not newline, then insert. CDP path should focus + set selection via the same helper or a small shared content/CDP preamble so caret cannot remain mid-body.

Acceptance / regression

• Append URL always appears after full body, on its own line when requested.
• No mid-sentence splice across repeated appends.
• Fixture test for caret-at-end before insert.

Owner

extension

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Priority: P0 · Owner: extension

[LakshmanTurlapati]

Fixed in #143: insert_text accepts position: "end" and an editable selector, so appended text lands at the end of the field instead of wherever the caret was.