test(missions): a composed node is offered the same help as a solo one

Every composed run so far reports `subagents: 0`, and the honest question is
whether that is the tasks being small or the capability being absent. It is the
former, and this is what says so: a composed node's task text is built by
`microvm_turn_executor` and then wrapped by the SAME `vm_prompt` inside
`run_inside`, so one prompt builder serves both paths and both carry the `Agent`
tool offer and the `verifier` / `explorer` roles.

Asserted rather than left to code reading, because if someone gave composed
nodes their own prompt without the offer, the difference would show up only as a
count nobody was watching — and "the graph fanned out but no node did" is
indistinguishable from "no node needed to".

The roles are read from `agent_definitions()` rather than spelled out, so adding
a role without mentioning it in the prompt fails here instead of shipping a role
the lead is never told about.

535 tests pass, clippy clean.

Co-Authored-By: Claude Opus 5 <[email protected]>

crates/cm-api/src/microvm_executor.rs

@@ -949,6 +949,24 @@ mod tests {
         assert!(!BLOCKS_PROBE.contains(GUEST_REPO), "{BLOCKS_PROBE}");
     }
 
+    /// EVERY VM turn is offered delegation, composed nodes included.
+    ///
+    /// A composed node's task text is built by `microvm_turn_executor` and then
+    /// wrapped by this same `vm_prompt` inside `run_inside`, so one prompt
+    /// builder serves both paths. Composed runs report `subagents: 0` so far,
+    /// and this is what says that is the TASKS being small rather than the
+    /// capability being absent — if someone gave composed nodes their own
+    /// prompt without the offer, the difference would otherwise show up only as
+    /// a count nobody was watching.
+    #[test]
+    fn every_vm_turn_is_offered_the_same_help() {
+        let p = vm_prompt("do the thing");
+        assert!(p.contains("Agent tool"), "{p}");
+        for role in agent_definitions().as_object().unwrap().keys() {
+            assert!(p.contains(role.as_str()), "the prompt must name the `{role}` role: {p}");
+        }
+    }
+
     /// The agent must not be told to push: delivery is host-side, and the guest
     /// deliberately holds no forge credentials.
     #[test]