Implement centralized transactional fix for command batch failures (#229)

* Agent Host changes for agents/fix-command-batch-history-restore

* Implement centralized transactional fix for command batch failures - #1

* The batch rollback tests compile, are formatted and expect the tab that was in front

The new module used a private helper of plugins_tests and an unused import; the plugin test
asserted tab 0 was in front, but it opens a second file first, which is the one in front
when the plugin starts and the one the rollback puts back.

---------

Co-authored-by: bflatastic <bombayapirat@gmail.com>

crates/engine/src/batch_rollback_tests.rs

@@ -0,0 +1,63 @@
+use serde_json::json;
+
+use crate::plugins_tests::{OnRefusal, install, manifest, script};
+use crate::{EngineError, Session};
+
+fn id(value: &serde_json::Value) -> crate::NodeId {
+    crate::params::id_of(&value["id"]).unwrap()
+}
+
+#[test]
+fn failed_group_closes_documents_opened_inside_it() {
+    let mut s = Session::new();
+    let original = id(&s.execute("shape.rectangle", &json!({"x": 0, "y": 0, "width": 10, "height": 10})).unwrap());
+    let before_journal = s.journal.clone();
+    let before_history = s.ds().unwrap().history.undo.len();
+
+    let result = s.execute(
+        "command.batch",
+        &json!({
+            "label": "Open then fail",
+            "commands": [
+                {"command": "file.new", "params": {"name": "Temporary"}},
+                {"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.docs.len(), 1);
+    assert_eq!(s.active, 0);
+    assert!(s.doc().unwrap().contains(original));
+    assert_eq!(s.ds().unwrap().history.undo.len(), before_history);
+    assert_eq!(s.journal, before_journal);
+}
+
+#[test]
+fn failed_plugin_run_restores_each_document_without_restoring_unrelated_state() {
+    let mut s = Session::new();
+    s.execute("file.new", &json!({"name": "Second"})).unwrap();
+    let before_history: Vec<_> = s.docs.iter().map(|ds| ds.history.undo.len()).collect();
+    let calls = [
+        ("shape.rectangle", json!({"x": 0, "y": 0, "width": 10, "height": 10})),
+        ("doc.nextTab", json!({})),
+        ("shape.rectangle", json!({"x": 20, "y": 0, "width": 10, "height": 10})),
+        ("node.set", json!({"id": 999999, "props": {"name": "must fail"}})),
+    ];
+    install(&mut s, manifest("org.test.rollback", "write", &[]), &script(&calls, OnRefusal::Fail, ""));
+    s.message = Some("keep this".into());
+    let before_journal = s.journal.clone();
+    let before_message = s.message.clone();
+    // The new file is the one in front when the plugin starts.
+    let before_active = s.active;
+
+    let result = s.execute("plugin.run", &json!({"id": "org.test.rollback"}));
+
+    assert!(matches!(result, Err(EngineError::Other(_))));
+    assert_eq!(s.docs.iter().map(|ds| ds.doc.node(ds.page).map_or(0, |page| page.children.len())).collect::<Vec<_>>(), vec![0, 0]);
+    assert_eq!(s.active, before_active, "the tab in front is put back");
+    assert_eq!(s.docs.iter().map(|ds| ds.history.undo.len()).collect::<Vec<_>>(), before_history);
+    assert_eq!(s.journal, before_journal);
+    assert_eq!(s.message, before_message);
+}