diff --git a/crates/engine/src/cmd/mod.rs b/crates/engine/src/cmd/mod.rs
index f0f1141f..a9d91aff 100644
--- a/crates/engine/src/cmd/mod.rs
+++ b/crates/engine/src/cmd/mod.rs
@@ -355,6 +355,11 @@ pub(crate) fn with_param(p: &Value, key: &str, v: Value) -> Value {
 
 /// Targets: `ids` / `id` params, else the selection.
 pub(crate) fn targets(s: &Session, p: &Value) -> Result<Vec<ShapeId>> {
+    if let Some(a) = p.get("ids").and_then(Value::as_array)
+        && let Some(v) = a.iter().find(|v| v.as_u64().and_then(|v| u32::try_from(v).ok()).is_none())
+    {
+        return Err(bad("shape", format!("`ids` has an invalid shape id: {v}")));
+    }
     if let Some(ids) = ids_param(p, "ids")
         && !ids.is_empty()
     {
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 18f55827..5105fcf3 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -5515,3 +5515,15 @@ fn transition_timing_invalid_after_keeps_value() {
     s.execute("transition.timing", &json!({"after": null})).unwrap();
     assert_eq!(after(&s), None);
 }
+
+
+#[test]
+fn invalid_ids_array_never_falls_back_to_the_selection() {
+    let mut s = session();
+    let a = s.execute("shape.insert", &json!({"preset": "rect", "rect": [100, 100, 100, 100]})).unwrap()["id"].as_u64().unwrap();
+    for ids in [json!([-1]), json!([1.5]), json!([4294967296u64]), json!([-1, a])] {
+        let r = s.execute("edit.delete", &json!({ "ids": ids }));
+        assert!(matches!(r, Err(crate::EngineError::BadParams { .. })), "invalid ids {ids} gave {r:?}");
+        assert!(s.doc().unwrap().shape(deckcraft_model::ShapeId(a as u32)).is_some(), "shape deleted for {ids}");
+    }
+}