Sketch on a cylinder primitive's caps; format 15 (#460)

* Sketch on a cylinder primitive's caps (#420)

A solid.cylinder's caps carried no construction certificate, so a sketch
on its top or bottom was refused unless fixed:true (#420's crossed
cylinders, built from primitives).

- kernel: FaceSource::CylinderCap { producer, high, plane };
  Body::with_cylinder_certificate turns a cylinder's two extrude caps into
  certified caps. kernel::cylinder's output is unchanged for its other
  callers.
- doc: FaceCertificate::CylinderCap { high }, named F<id>:top / F<id>:bottom
  as the cylinder's face names already are; New Body and Join cylinders
  are certified, shells carry it as their planar source.
- format 15: designs can store the new certificate kind; version 14
  designs need no change, and older builds ask for an update instead of
  meeting an unknown kind.

Tests: top and bottom attachments follow a height and base edit and a
reopen; crossed joined cylinders keep both caps attachable; a shelled
cylinder's floor keeps its cap identity; malformed certificate JSON is
refused.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YDDPmNdRoBgkHcLeUDKVfb

* Format 15 also covers sketch_axis links (#448)

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YDDPmNdRoBgkHcLeUDKVfb

---------

Co-authored-by: Claude Opus 5.5 <[email protected]>

crates/engine/src/cmd/face_tests.rs

@@ -317,3 +317,66 @@ fn join_covering_a_whole_attached_face_loses_the_attachment_without_moving_it()
     assert!(!failed(&s, top));
     assert!((s.model.state().sketch(top).unwrap().plane.origin.z - 10.).abs() < 1e-9);
 }
+
+fn certificate_of(s: &Session, sketch: u64) -> Option<solidcraft_doc::config::FaceCertificate> {
+    let FeatureKind::Sketch { plane: PlaneRef::Face { anchor: Some(anchor), .. }, .. } = &s.doc.feature(sketch).unwrap().kind else {
+        return None;
+    };
+    anchor.target.certificate.clone()
+}
+
+#[test]
+fn cylinder_primitive_caps_take_attachments_that_follow_edits_and_reopen() {
+    use solidcraft_doc::config::FaceCertificate;
+    let mut s = Session::default();
+    run(&mut s, "solid.cylinder", json!({"radius":10,"height":40,"name":"Post"}));
+    let top = run(&mut s, "sketch.create", json!({"plane":{"face":[2,1,40]}}))["sketch"].as_u64().unwrap();
+    run(&mut s, "sketch.finish", json!({}));
+    let bottom = run(&mut s, "sketch.create", json!({"plane":{"face":[2,1,0]}}))["sketch"].as_u64().unwrap();
+    run(&mut s, "sketch.finish", json!({}));
+    assert_eq!(certificate_of(&s, top), Some(FaceCertificate::CylinderCap { high: true }));
+    assert_eq!(certificate_of(&s, bottom), Some(FaceCertificate::CylinderCap { high: false }));
+    let heights = |s: &Session| {
+        let state = s.model.state();
+        (state.sketch(top).unwrap().plane.origin.z, state.sketch(bottom).unwrap().plane.origin.z)
+    };
+    run(&mut s, "timeline.edit", json!({"feature":"Post","set":{"height":"55","base":[0,0,5]}}));
+    s.refresh();
+    assert!(s.model.results.iter().all(|result| result.error.is_none()), "{:?}", s.model.results);
+    let (high, low) = heights(&s);
+    assert!((high - 60.).abs() < 1e-9 && (low - 5.).abs() < 1e-9, "{high} {low}");
+    let mut reopened = Session::new(Document::from_json(&s.doc.to_json()).unwrap());
+    reopened.refresh();
+    assert!(reopened.model.results.iter().all(|result| result.error.is_none()), "{:?}", reopened.model.results);
+    assert_eq!(heights(&reopened), (high, low));
+}
+
+#[test]
+fn crossed_cylinder_primitives_keep_their_caps_attachable() {
+    let mut s = Session::default();
+    run(&mut s, "solid.cylinder", json!({"radius":10,"height":40}));
+    run(&mut s, "solid.cylinder", json!({"radius":5,"height":40,"base":[-20,0,20],"axis":"X","operation":"join"}));
+    assert_eq!(s.model.state().bodies.len(), 1);
+    for face in [[0., 0., 40.], [20., 0., 20.]] {
+        let sketch = run(&mut s, "sketch.create", json!({"plane":{"face":face}}))["sketch"].as_u64().unwrap();
+        run(&mut s, "sketch.finish", json!({}));
+        assert!(certificate_of(&s, sketch).is_some(), "{face:?}");
+    }
+}
+
+#[test]
+fn shelled_cylinder_floor_keeps_its_cap_identity() {
+    use solidcraft_doc::config::FaceCertificate;
+    let mut s = Session::default();
+    run(&mut s, "solid.cylinder", json!({"radius":10,"height":40}));
+    run(&mut s, "solid.shell", json!({"faces":[[2,1,40]],"thickness":2}));
+    let floor = run(&mut s, "sketch.create", json!({"plane":{"face":[2,1,2]}}))["sketch"].as_u64().unwrap();
+    assert!(
+        matches!(
+            certificate_of(&s, floor),
+            Some(FaceCertificate::ShellPlanar { source, inner: true, .. }) if *source == FaceCertificate::CylinderCap { high: false }
+        ),
+        "{:?}",
+        certificate_of(&s, floor)
+    );
+}