perf(mcp): move command list rows instead of cloning (#8844)

crates/automation/src/server.rs

@@ -412,6 +412,14 @@ fn strict_node(v: &mut Value, defs: &serde_json::Map<String, Value>, depth: usiz
     }
 }
 
+/// Both the bare engine list and older bridge wrappers own their rows already.
+fn into_command_rows(mut reply: Value) -> Vec<Value> {
+    match reply {
+        Value::Array(rows) => rows,
+        _ => reply.get_mut("commands").and_then(Value::as_array_mut).map(std::mem::take).unwrap_or_default(),
+    }
+}
+
 fn ok_json(v: &Value) -> CallToolResult {
     let text = match json_bytes(v).and_then(|bytes| String::from_utf8(bytes).map_err(|error| AutomationError::Other(error.to_string()))) {
         Ok(text) => text,
@@ -827,10 +835,7 @@ impl PhotocraftMcp {
         };
         let needle = p.filter.map(|f| f.to_lowercase());
         let enabled_only = p.enabled_only.unwrap_or(false);
-        let items: Vec<Value> = all
-            .as_array()
-            .cloned()
-            .unwrap_or_else(|| all.get("commands").and_then(Value::as_array).cloned().unwrap_or_default())
+        let items: Vec<Value> = into_command_rows(all)
             .into_iter()
             .filter(|c| {
                 needle.as_ref().is_none_or(|n| photocraft_engine::commands::list_entry_matches(c, n))
@@ -1083,6 +1088,29 @@ pub fn render_document_png(doc: &photocraft_doc::Document, max_side: u32) -> Res
 mod tests {
     use super::*;
 
+    #[test]
+    fn command_rows_keep_bare_and_wrapped_replies_compatible() {
+        let rows = json!([{"id":"first","params":{"nested":[1,2]}}, {"id":"second","enabled":false}]);
+        assert_eq!(into_command_rows(rows.clone()), rows.as_array().unwrap().clone());
+        assert_eq!(into_command_rows(json!({"commands":rows,"other":"ignored"})), rows.as_array().unwrap().clone());
+        for reply in [json!(null), json!(false), json!(3), json!("invalid"), json!({}), json!({"commands":null}), json!({"commands":{}}), json!([])] {
+            assert!(into_command_rows(reply).is_empty());
+        }
+    }
+
+    #[test]
+    fn command_rows_reuse_the_owned_array_and_nested_strings() {
+        for wrapped in [false, true] {
+            let rows = json!([{"id":"first","params":"documentation".repeat(64)}]);
+            let array = rows.as_array().unwrap().as_ptr();
+            let text = rows[0]["params"].as_str().unwrap().as_ptr();
+            let reply = if wrapped { Value::Object([("commands".into(), rows)].into_iter().collect()) } else { rows };
+            let moved = into_command_rows(reply);
+            assert_eq!(moved.as_ptr(), array, "wrapped={wrapped}: move the original allocation");
+            assert_eq!(moved[0]["params"].as_str().unwrap().as_ptr(), text, "wrapped={wrapped}: retain nested allocations");
+        }
+    }
+
     #[test]
     fn strict_schema_inlines_refs_and_stops_on_recursive_definitions() {
         // A definition that refers to itself: inlining stops at a depth instead of looping.