fix(comments): a locked reply keeps the comment or reply it answers

Deleting a comment or a reply took every reply to it, locked or not: only
the target's own Locked flag was checked. A locked reply can't be deleted
on its own, so delete_annotation now refuses while anything that would go
with the target is locked (pop-ups follow their comment).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/annot/src/modify.rs

@@ -80,6 +80,16 @@ pub fn delete_annotation(doc: &mut Document, page: usize, index: usize) -> Resul
     // An inline comment has no reference to collect; the pop-up it names still goes.
     let seed = target.as_ref().or_else(|| target.as_dict().and_then(|d| d.reference(b"Popup")));
     let doomed = with_replies_and_popups(doc, &list, seed);
+    // A locked reply can't be deleted on its own, so it doesn't go with the comment or reply it
+    // answers either. Pop-ups follow their comment.
+    for (_, e) in list.iter().enumerate().filter(|(i, e)| *i != index && goes_with(e, &doomed)) {
+        let obj = doc.resolve(e);
+        if let Some(d) = obj.as_dict().filter(|d| d.name(b"Subtype") != Some(b"Popup".as_slice()))
+            && annotation_flags(doc, d) & FLAG_LOCKED != 0
+        {
+            return Err(AnnotError::Invalid("a reply to it is locked".into()));
+        }
+    }
     let kept: Vec<Object> = list.into_iter().enumerate().filter(|(i, e)| *i != index && !goes_with(e, &doomed)).map(|(_, e)| e).collect();
     Ok(set_annots(doc, p, kept)?)
 }

crates/annot/src/tests.rs

@@ -229,6 +229,25 @@ fn delete_takes_popup_and_reply_chain() {
     assert_eq!(delete_annotation(&mut doc, 0, 9), Err(AnnotError::NoSuchAnnotation { page: 0, index: 9 }));
 }
 
+/// A locked reply can't be deleted, so it doesn't go with what it answers either: deleting the
+/// reply above it, or the comment, is refused and changes nothing; once it is unlocked they go.
+#[test]
+fn a_locked_reply_keeps_what_it_answers() {
+    let mut doc = fixture();
+    let note = add_annotation(&mut doc, &new(0, Shape::Note { at: [100.0, 100.0], icon: NoteIcon::Comment }), &meta("n")).unwrap();
+    let reply = add_reply(&mut doc, 0, note, "first", "Bob", &meta("r1")).unwrap();
+    let answer = add_reply(&mut doc, 0, reply, "locked answer", "Ada", &meta("r2")).unwrap();
+    set_locked(&mut doc, 0, answer, true).unwrap();
+    let before = list(&doc, 0).len();
+    assert_eq!(delete_annotation(&mut doc, 0, reply), Err(AnnotError::Invalid("a reply to it is locked".into())));
+    assert_eq!(delete_annotation(&mut doc, 0, note), Err(AnnotError::Invalid("a reply to it is locked".into())));
+    assert_eq!(list(&doc, 0).len(), before, "nothing went");
+    set_locked(&mut doc, 0, answer, false).unwrap();
+    delete_annotation(&mut doc, 0, reply).unwrap();
+    let left: Vec<String> = list(&doc, 0).iter().map(|d| text(d, b"Contents")).collect();
+    assert!(!left.iter().any(|t| t == "first" || t == "locked answer"), "the reply and its answer went: {left:?}");
+}
+
 /// A reply or pop-up written inline in `/Annots` (a file can, though the standard asks for
 /// references) goes with the comment it points at, and so does a pop-up an inline reply or an
 /// inline comment names. An unrelated inline comment stays until it is deleted itself.

parity/acrobat-features.toml

@@ -4003,8 +4003,8 @@ milestone = "M5"
 status = "shipped"
 commands = ["comment.list"]
 tools = ["comment_delete"]
-evidence = ["crates/ui-egui/tests/it/comments.rs::comments_are_selected_moved_and_deleted_with_the_select_tool", "crates/annot/src/tests.rs::delete_takes_popup_and_reply_chain", "crates/ui-egui/tests/it/comments.rs::one_reply_is_deleted_from_its_menu_and_the_thread_stays", "crates/ui-egui/src/tools/comments/tests.rs::a_kept_comment_is_found_where_a_delete_moved_it", "crates/automation/tests/it/automation.rs::deleting_a_reply_keeps_its_comment_and_the_other_replies"]
-notes = "deletes the pop-up and the reply thread. One reply is deleted from its own \"…\" in the Comments panel (comment_delete with the reply's id, or page and index), with its pop-up and the replies to it: the comment and its other replies stay, one undo step, and the card stays selected. A locked reply can't be deleted."
+evidence = ["crates/ui-egui/tests/it/comments.rs::comments_are_selected_moved_and_deleted_with_the_select_tool", "crates/annot/src/tests.rs::delete_takes_popup_and_reply_chain", "crates/ui-egui/tests/it/comments.rs::one_reply_is_deleted_from_its_menu_and_the_thread_stays", "crates/ui-egui/src/tools/comments/tests.rs::a_kept_comment_is_found_where_a_delete_moved_it", "crates/automation/tests/it/automation.rs::deleting_a_reply_keeps_its_comment_and_the_other_replies", "crates/annot/src/tests.rs::a_locked_reply_keeps_what_it_answers"]
+notes = "deletes the pop-up and the reply thread. One reply is deleted from its own \"…\" in the Comments panel (comment_delete with the reply's id, or page and index), with its pop-up and the replies to it: the comment and its other replies stay, one undo step, and the card stays selected. A locked reply can't be deleted, nor the comment or reply it answers while it is locked."
 
 [[feature]]
 id = "comment.keyboard-nudge"