fix(ui): Select Other keeps its list readable on dense meshes (#636)

Select Other keeps at most 20 rows per kind, nearest first, so a dense spot (a modelled thread, an imported mesh) no longer lists thousands of rows. The title shows how many were under the cursor in all, and ui.selectOther reports it as total.

crates/ui-egui/src/select_other_tests.rs

@@ -170,3 +170,27 @@ fn rows_name_points_by_their_curves() {
     let rows = labels(&h);
     assert!(rows.iter().any(|r| r.starts_with("Point (") && r.contains("centre")), "{rows:?}");
 }
+
+#[test]
+fn a_dense_spot_is_capped_per_kind_and_reports_the_total() {
+    let mut h = Harness::new();
+    h.app.ui.show_origin = false;
+    h.app.run("sketch.create", json!({"plane":"XY"})).unwrap();
+    // Thirty lines drawn on top of each other: one kind of thing, far beyond the per-kind cap.
+    for _ in 0..30 {
+        h.app.run("sketch.line", json!({"points":[[0,10],[20,10]],"infer":false,"connect":false})).unwrap();
+    }
+    h.app.cam.distance = 60.0;
+    h.settle();
+    let at = h.call("ui.at", json!({"sketch":[10,10]}))["result"].clone();
+    h.step(&json!({"hold": at})).unwrap();
+    assert!(crate::select_other::is_open(&h.app));
+    let d = crate::select_other::describe(&h.app);
+    let rows = d["rows"].as_array().expect("rows");
+    let lines = rows.iter().filter(|r| r["label"].as_str().is_some_and(|l| l.starts_with("Line "))).count();
+    assert_eq!(lines, 20, "at most 20 rows of one kind, nearest first: {rows:?}");
+    assert_eq!(rows[0]["label"], json!("Line 1"), "the nearest still leads");
+    let total = d["total"].as_u64().expect("total");
+    assert!(total >= 30, "the total counts every candidate, not just the rows: {total}");
+    assert!((total as usize) < rows.len() + 30, "the list is truncated: {total} total, {} rows", rows.len());
+}