Type: typing a list's start in a continued paragraph starts no list

In a threaded frame whose first paragraph continues from the frame
before, the text at the frame's start is not the start of a paragraph,
and the frame draws no list marker for it. Typing "* " or "1. " there
removed the characters and set a list that never showed. typed_list_at
now returns None for that paragraph.

crates/doc/src/text/object.rs

@@ -200,14 +200,16 @@ impl TextObject {
     }
     /// The list that the characters before byte `at` start ([`ParaList::typed`]) with the byte
     /// where their paragraph starts: when the plain text from the start of the paragraph up to
-    /// `at` is a list's start followed by a space, and the paragraph is in no list. None otherwise.
+    /// `at` is a list's start followed by a space, and the paragraph is in no list. None otherwise,
+    /// and for a first paragraph that continues from the frame before
+    /// ([`TextObject::first_para_continues`]).
     pub fn typed_list_at(&self, at: usize) -> Option<(usize, ParaList)> {
         let text = self.plain_text();
         let before = text.get(..at)?;
         let start = before.rfind('\n').map_or(0, |i| i + 1);
         let list = ParaList::typed(before[start..].strip_suffix(' ')?)?;
         let index = before.bytes().filter(|&b| b == b'\n').count();
-        self.para_at(index).list.is_none().then_some((start, list))
+        (!(index == 0 && self.first_para_continues) && self.para_at(index).list.is_none()).then_some((start, list))
     }
     /// Apply `f` to the attributes of paragraphs `range` (indices; None = every paragraph).
     pub fn edit_paras(&mut self, range: Option<std::ops::Range<usize>>, mut f: impl FnMut(&mut ParaStyle)) {

crates/doc/src/text/tests.rs

@@ -239,6 +239,19 @@ fn typed_list_starts_are_found_at_a_paragraphs_start() {
     assert_eq!(t.typed_list_at(19), Some((16, letters)));
 }
 
+/// In a threaded frame whose first paragraph continues from the frame before, the text at the
+/// frame's start is not the start of a paragraph, so typing a list's start there starts nothing.
+/// The paragraphs after it still start lists.
+#[test]
+fn typed_list_starts_skip_a_continued_paragraph() {
+    let dot = ParaList::bulleted(Bullet::Dot);
+    let mut t = TextObject::point(Point::ZERO, "* Pears\n# ", CharStyle::default());
+    assert_eq!(t.typed_list_at(2), Some((0, dot)));
+    t.first_para_continues = true;
+    assert_eq!(t.typed_list_at(2), None, "a continued paragraph starts no list");
+    assert_eq!(t.typed_list_at(10), Some((8, dot)));
+}
+
 #[test]
 fn character_controls_reject_collapsed_and_nonfinite_transforms() {
     let mut t = TextObject::point(Point::ZERO, "Text", CharStyle::default());