Parameter and feature edits report the features they restored from the evaluation cache: setting a parameter back (or a timeline.edit back) reused the earlier results for the same inputs, so the geometry changed back but recomputed said 0, which read as "nothing rebuilt". The evaluator now counts cache hits as last_restored, and parameters.change, timeline.edit, timeline.redefine and solid.press_pull on a fillet or chamfer face report it as restored next to recomputed (params docs, the MCP set_parameter description and docs/mcp.md say what each counts). Tests: setting a parameter back and a feature edit back report restored, in the evaluator and through the commands

crates/engine/src/cmd/parameters_tests.rs

@@ -67,6 +67,25 @@ fn width_follows_an_expression() {
     assert!(e.contains("expected a length, got an angle"), "{e}");
 }
 
+/// Setting a parameter back rebuilds nothing (the earlier results are reused) and says so: the
+/// features it restored are reported next to `recomputed`, so `recomputed: 0` is not mistaken
+/// for "nothing changed". timeline.edit reports the same.
+#[test]
+fn setting_a_parameter_back_reports_restored_features() {
+    let mut s = Session::default();
+    block(&mut s);
+    let r = run(&mut s, "parameters.change", json!({"name": "len", "expression": "100 mm"}));
+    assert_eq!((r["recomputed"].as_u64(), r["restored"].as_u64()), (Some(2), Some(0)), "{r}");
+    let r = run(&mut s, "parameters.change", json!({"name": "len", "expression": "60 mm"}));
+    assert_eq!((r["recomputed"].as_u64(), r["restored"].as_u64()), (Some(0), Some(2)), "{r}");
+    assert!(rel(volume(&mut s), 40.0 * 30.0 * 10.0) < 1e-9);
+    let r = run(&mut s, "timeline.edit", json!({"feature": "Extrude1", "set": {"extent": {"distance": "20"}}}));
+    assert_eq!((r["recomputed"].as_u64(), r["restored"].as_u64()), (Some(1), Some(0)), "{r}");
+    let r = run(&mut s, "timeline.edit", json!({"feature": "Extrude1", "set": {"extent": {"distance": "10"}}}));
+    assert_eq!((r["recomputed"].as_u64(), r["restored"].as_u64()), (Some(0), Some(1)), "{r}");
+    assert!(rel(volume(&mut s), 40.0 * 30.0 * 10.0) < 1e-9);
+}
+
 #[test]
 fn feature_inputs_are_named_and_editable() {
     let mut s = Session::default();