feat: lift runtime into language, start of zelus 2024 compatibility

doc/notes.typ

@@ -751,3 +751,20 @@ let hybrid ball () = y where
   and assert (y >= 0)
 ```
 Is this an issue?
+
+= Ideas
+
+== Continuous assertions with lifted runtime
+
+Given a synchronous node simulating a hybrid one :
+```zelus
+let hybrid sincos () = (sin, cos) where
+  rec der sin = cos init 0.0
+  and der cos = -. sin init 1.0
+
+let node sincos_sim = Solve.solve_ode45 sincos
+```
+We could create a primitive `Solve.assert_continuous` which would take as input
+an `'a value` and a function `'a -> Solve.cond`, where `Solve.cond` is a
+zero-crossing expression, for instance `fun v -> Solve.up(-. v)`. This could be
+passed along to a zero-crossing solver during continuous phases.