From 6eeac4fa04c72c74836d27848f2836227c737597 Mon Sep 17 00:00:00 2001
From: MarekSpodBiedry <73122968+MarekSpodBiedry@users.noreply.github.com>
Date: Wed, 14 Oct 2026 16:14:35 +0200
Subject: [PATCH] Keep the redo steps when a failed command batch rolls back
 (#196)

---
 crates/engine/src/batch_rollback_tests.rs | 22 ++++++++++++++++++++++
 crates/engine/src/lib.rs                  |  5 ++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/crates/engine/src/batch_rollback_tests.rs b/crates/engine/src/batch_rollback_tests.rs
index db0b7962..12d958cd 100644
--- a/crates/engine/src/batch_rollback_tests.rs
+++ b/crates/engine/src/batch_rollback_tests.rs
@@ -61,3 +61,25 @@ fn failed_plugin_run_restores_each_document_without_restoring_unrelated_state()
     assert_eq!(s.journal, before_journal);
     assert_eq!(s.message, before_message);
 }
+
+#[test]
+fn failed_group_keeps_the_redo_steps() {
+    let mut s = Session::new();
+    s.execute("shape.rectangle", &json!({"x": 0, "y": 0, "width": 10, "height": 10})).unwrap();
+    assert!(s.undo().unwrap());
+    assert_eq!(s.undo_depth().1, 1);
+
+    let result = s.execute(
+        "command.batch",
+        &json!({
+            "commands": [
+                {"command": "shape.rectangle", "params": {"x": 20, "y": 20, "width": 10, "height": 10}},
+                {"command": "node.set", "params": {"id": 999999, "props": {"name": "must fail"}}}
+            ]
+        }),
+    );
+
+    assert!(result.is_err());
+    assert_eq!(s.undo_depth().1, 1, "the redo step survives the failed batch");
+    assert!(s.redo().unwrap());
+}
diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index 3bc49a90..0d9eddf4 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -1082,6 +1082,8 @@ impl Session {
         self.ds()?;
         let before: Vec<_> =
             self.docs.iter().map(|ds| (ds.uid, ds.doc.clone(), ds.selection.clone(), ds.page, ds.history.undo.len(), ds.history.limit)).collect();
+        // An edit inside clears the redo steps; a failed group has to bring them back.
+        let redo_before: Vec<_> = self.docs.iter().map(|ds| ds.history.redo.clone()).collect();
         let active = self.active;
         let journal_len = self.journal.len();
 
@@ -1099,8 +1101,9 @@ impl Session {
 
         if result.is_err() {
             self.docs.retain(|ds| before.iter().any(|(uid, _, _, _, _, _)| *uid == ds.uid));
-            for (uid, doc, selection, page, undo_len, limit) in &before {
+            for ((uid, doc, selection, page, undo_len, limit), redo) in before.iter().zip(redo_before) {
                 if let Some(ds) = self.docs.iter_mut().find(|ds| ds.uid == *uid) {
+                    ds.history.redo = redo;
                     ds.doc = doc.clone();
                     ds.selection = selection.clone();
                     ds.page = *page;