fix: restore block menu delete undo

rust/spikes/leptos-tiptap-spike/src/editor_runtime/block_menu_document.rs

@@ -0,0 +1,112 @@
+//! block menu 使用的顶层块 JSON helper。
+
+use serde_json::{json, Value};
+
+use crate::DropPlacement;
+
+fn document_content_mut(document: &mut Value) -> Result<&mut Vec<Value>, String> {
+    document
+        .get_mut("content")
+        .and_then(Value::as_array_mut)
+        .ok_or_else(|| "文档 JSON 缺少顶层 content 数组".to_string())
+}
+
+pub(crate) fn duplicate_top_level_block(document: &mut Value, index: usize) -> Result<(), String> {
+    let content = document_content_mut(document)?;
+    let block = content
+        .get(index)
+        .cloned()
+        .ok_or_else(|| format!("找不到第 {index} 个块"))?;
+    content.insert(index + 1, block);
+    Ok(())
+}
+
+pub(crate) fn delete_top_level_block(document: &mut Value, index: usize) -> Result<(), String> {
+    let content = document_content_mut(document)?;
+    if index >= content.len() {
+        return Err(format!("找不到第 {index} 个块"));
+    }
+
+    if content.len() == 1 {
+        content[0] = json!({"type": "paragraph"});
+        return Ok(());
+    }
+
+    content.remove(index);
+    Ok(())
+}
+
+pub(crate) fn reorder_top_level_block(
+    document: &mut Value,
+    source: usize,
+    target: usize,
+    placement: DropPlacement,
+) -> Result<(), String> {
+    let content = document_content_mut(document)?;
+    if source >= content.len() || target >= content.len() {
+        return Err("拖拽目标超出当前顶层块范围".to_string());
+    }
+
+    let block = content.remove(source);
+    let mut insert_at = match placement {
+        DropPlacement::Before => target,
+        DropPlacement::After => target + 1,
+    };
+
+    if source < insert_at {
+        insert_at = insert_at.saturating_sub(1);
+    }
+
+    if insert_at > content.len() {
+        insert_at = content.len();
+    }
+
+    content.insert(insert_at, block);
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+
+    use super::*;
+
+    #[test]
+    fn delete_only_top_level_block_keeps_empty_paragraph() {
+        let mut document = json!({
+            "type": "doc",
+            "content": [
+                {"type": "paragraph", "content": [{"type": "text", "text": "A"}]}
+            ]
+        });
+
+        delete_top_level_block(&mut document, 0).expect("delete block");
+
+        assert_eq!(
+            document,
+            json!({"type": "doc", "content": [{"type": "paragraph"}]})
+        );
+    }
+
+    #[test]
+    fn reorder_top_level_block_adjusts_target_after_source_removal() {
+        let mut document = json!({
+            "type": "doc",
+            "content": [
+                {"type": "paragraph", "attrs": {"id": "a"}},
+                {"type": "paragraph", "attrs": {"id": "b"}},
+                {"type": "paragraph", "attrs": {"id": "c"}}
+            ]
+        });
+
+        reorder_top_level_block(&mut document, 0, 2, DropPlacement::After).expect("reorder block");
+
+        let ids: Vec<_> = document["content"]
+            .as_array()
+            .expect("content")
+            .iter()
+            .map(|node| node["attrs"]["id"].as_str().unwrap_or_default())
+            .collect();
+        assert_eq!(ids, vec!["b", "c", "a"]);
+    }
+}

rust/spikes/leptos-tiptap-spike/src/editor_runtime/mod.rs

@@ -1,5 +1,6 @@
 pub(crate) mod attachment_links;
 pub(crate) mod attachment_upload;
+pub(crate) mod block_menu_document;
 pub(crate) mod block_menu_legacy_html;
 pub(crate) mod command_sync;
 pub(crate) mod dom_selection;