CLI snapshot takes --in; an unknown command suggests close ids (#1301)

snapshot starts from --in (a design or STEP file) with the script on top, as run does, and refuses options it doesn't take; an unknown command id names the closest registered ids.

crates/engine/src/tests.rs

@@ -837,6 +837,20 @@ fn only_own_ids_name_commands() {
     }
 }
 
+/// An unknown command's error names the ids it was probably meant to be: a typo's, or the
+/// command that ends in the same word.
+#[test]
+fn unknown_commands_suggest_the_closest_ids() {
+    let mut s = Session::default();
+    let mut msg = |id: &str| s.execute(id, &serde_json::json!({})).unwrap_err().to_string();
+    assert_eq!(msg("file.open"), "unknown command `file.open` (did you mean `doc.open`?)");
+    assert!(msg("solid.extrud").starts_with("unknown command `solid.extrud` (did you mean `solid.extrude`"), "{}", msg("solid.extrud"));
+    assert!(msg("Extrude").contains("`solid.extrude`"), "{}", msg("Extrude"));
+    assert_eq!(msg("FusionFilletEdgesCommand"), "unknown command `FusionFilletEdgesCommand`");
+    let long = "x".repeat(10_000);
+    assert_eq!(msg(&long), format!("unknown command `{long}`"));
+}
+
 #[test]
 fn sample_design_builds() {
     let mut s = Session::default();