bxcore: a turn's speaker, SessionUpdated's turn, the session-state messages

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

crates/bxcore/tests/memory_wire.rs

@@ -1,9 +1,11 @@
-//! The eight memory messages against byte-exact fixtures, each refusing an unknown key (M5a spec,
-//! section 7). Do not edit these or the fixtures.
+//! The memory messages against byte-exact fixtures, each refusing an unknown key: the eight of M5a
+//! (M5a spec, section 7) and the session-state question of M5c (M5c spec, section 7). Do not edit
+//! these or the fixtures.
 
 use bxcore::{
     CallId, DataClass, Empty, Envelope, MemoryAdmin, MemoryAdminReply, MemoryBlockReply,
-    MemoryCall, MemoryCommand, Message, Reindexed, SessionId, SessionUpdated, ToolRequest,
+    MemoryCall, MemoryCommand, Message, Reindexed, SessionId, SessionState, SessionStateReply,
+    SessionUpdated, ToolRequest,
 };
 
 const SESSION: &str = "mm-r0000000000000000000000001";
@@ -53,6 +55,7 @@ fn the_eight_messages() {
         1,
         Message::SessionUpdated(SessionUpdated {
             session: SessionId::new(SESSION).unwrap(),
+            turn: 3,
         }),
     );
     check(
@@ -96,6 +99,58 @@ fn the_eight_messages() {
     );
 }
 
+/// `turn` has no default: a `session_updated` without it, as a `loopd` from before M5c sent, is
+/// refused, never read as turn 0 (M5c spec, section 5).
+#[test]
+fn a_session_updated_without_turn_is_refused() {
+    let old = r#"{"v":1,"id":1,"final":true,"msg":{"kind":"session_updated","body":{"session":"mm-r0000000000000000000000001"}}}"#;
+    let error = serde_json::from_str::<Envelope>(old).unwrap_err();
+    assert!(
+        error.to_string().contains("missing field `turn`"),
+        "{error}"
+    );
+}
+
+/// `memoryd` asks `brokerd` for a session's state on `state.sock` (M5c spec, section 7).
+#[test]
+fn the_session_state_messages() {
+    check(
+        "session_state.json",
+        1,
+        Message::SessionState(SessionState {
+            session: SessionId::new(SESSION).unwrap(),
+        }),
+    );
+    check(
+        "session_state_reply.json",
+        1,
+        Message::SessionStateReply(SessionStateReply {
+            class: DataClass::Private,
+            untrusted: true,
+        }),
+    );
+}
+
+/// Neither field of the reply has a default: a reply without one is refused, never read as a
+/// clean or `public` session.
+#[test]
+fn a_session_state_reply_needs_both_fields() {
+    let text = fixture("session_state_reply.json");
+    for (field, without) in [
+        ("class", text.replacen(r#""class":"private","#, "", 1)),
+        ("untrusted", text.replacen(r#","untrusted":true"#, "", 1)),
+    ] {
+        assert_ne!(without, text, "{field}: the fixture holds the field");
+        let error = serde_json::from_str::<Envelope>(&without).unwrap_err();
+        assert!(
+            error
+                .to_string()
+                .contains(&format!("missing field `{field}`")),
+            "{field}: {error}"
+        );
+    }
+}
+
 #[test]
 fn every_command_has_its_name() {
     for (command, name) in [