message: Update PlainBasePart to only split on space boundaries
diff: @@ -186,7 +186,11 @@ abstract class PlainBasePart extends BasePart {
  }
  // when not pasting or dropping text, reject characters that should start a pill candidate
  if (inputType !== "insertFromPaste" && inputType !== "insertFromDrop") {
  - return chr !== "@" && chr !== "#" && chr !== ":";
  + if (chr !== "@" && chr !== "#" && chr !== ":") {
  + return true;
  + }
  + // only split if the previous character is a space
  + return this._text[offset - 1] !== " ";
  }
  return true;
  }
  