Support multi-statement mutations (insert + edge in one query)

Allow mutation queries to contain multiple sequential statements that
execute atomically within a single transactional run. This enables
patterns like inserting a node and its edges in one query:

    query add_and_link($name: String, $age: I32, $friend: String) {
        insert Person { name: $name, age: $age }
        insert Knows { from: $name, to: $friend }
    }

Changes span the full compiler-to-execution pipeline:
- Grammar: mutation_body = { mutation_stmt+ }
- AST: QueryDecl.mutations: Vec<Mutation>
- IR: MutationIR.ops: Vec<MutationOpIR>
- Execution: loop over ops, accumulate affected counts

Cross-statement visibility works because each statement's commit_updates
advances the manifest state, so subsequent statements see prior writes.
Atomicity comes from the existing run mechanism (begin_run/publish_run).

https://claude.ai/code/session_01E4VG2WXrZW8aeXFiqr8NwF

crates/omnigraph/src/exec/mod.rs

@@ -3335,24 +3335,30 @@ impl Omnigraph {
 
         let ir = lower_mutation_query(&query_decl)?;
 
-        match &ir.op {
-            MutationOpIR::Insert {
-                type_name,
-                assignments,
-            } => self.execute_insert(type_name, assignments, params).await,
-            MutationOpIR::Update {
-                type_name,
-                assignments,
-                predicate,
-            } => {
-                self.execute_update(type_name, assignments, predicate, params)
-                    .await
-            }
-            MutationOpIR::Delete {
-                type_name,
-                predicate,
-            } => self.execute_delete(type_name, predicate, params).await,
+        let mut total = MutationResult::default();
+        for op in &ir.ops {
+            let result = match op {
+                MutationOpIR::Insert {
+                    type_name,
+                    assignments,
+                } => self.execute_insert(type_name, assignments, params).await?,
+                MutationOpIR::Update {
+                    type_name,
+                    assignments,
+                    predicate,
+                } => {
+                    self.execute_update(type_name, assignments, predicate, params)
+                        .await?
+                }
+                MutationOpIR::Delete {
+                    type_name,
+                    predicate,
+                } => self.execute_delete(type_name, predicate, params).await?,
+            };
+            total.affected_nodes += result.affected_nodes;
+            total.affected_edges += result.affected_edges;
         }
+        Ok(total)
     }
 
     pub async fn branch_merge(&mut self, source: &str, target: &str) -> Result<MergeOutcome> {

crates/omnigraph/tests/end_to_end.rs

@@ -644,6 +644,43 @@ async fn mutation_insert_edge() {
     assert_eq!(names.value(0), "Alice");
 }
 
+#[tokio::test]
+async fn mutation_multi_insert_node_and_edge() {
+    let dir = tempfile::tempdir().unwrap();
+    let mut db = init_and_load(&dir).await;
+
+    // In one atomic mutation: insert Eve + edge Eve→Alice
+    let result = mutate_main(
+        &mut db,
+        MUTATION_QUERIES,
+        "insert_person_and_friend",
+        &mixed_params(&[("$name", "Eve"), ("$friend", "Alice")], &[("$age", 22)]),
+    )
+    .await
+    .unwrap();
+
+    assert_eq!(result.affected_nodes, 1);
+    assert_eq!(result.affected_edges, 1);
+
+    // Verify traversal: Eve → Alice
+    let qr = query_main(
+        &mut db,
+        TEST_QUERIES,
+        "friends_of",
+        &params(&[("$name", "Eve")]),
+    )
+    .await
+    .unwrap();
+    assert_eq!(qr.num_rows(), 1);
+    let batch = qr.concat_batches().unwrap();
+    let names = batch
+        .column(0)
+        .as_any()
+        .downcast_ref::<StringArray>()
+        .unwrap();
+    assert_eq!(names.value(0), "Alice");
+}
+
 #[tokio::test]
 async fn mutation_update_node() {
     let dir = tempfile::tempdir().unwrap();

crates/omnigraph/tests/helpers/mod.rs

@@ -35,6 +35,11 @@ query remove_person($name: String) {
 query remove_friendship($from: String) {
     delete Knows where from = $from
 }
+
+query insert_person_and_friend($name: String, $age: I32, $friend: String) {
+    insert Person { name: $name, age: $age }
+    insert Knows { from: $name, to: $friend }
+}
 "#;
 
 /// Init a repo and load the standard test data.