Host: fixes from the review, with regression tests

- one live instance per actor: check after the lock; dropping an instance kills it
- state snapshots keep target/ and .git/; only source copies skip them
- one shutdown deadline; output during shutdown is still routed
- deliveries route stdout meanwhile; a stuck stdin kills the instance
  (no partial lines) and the sender gets undeliverable; control requests
  are not blocked by a stuck delivery
- Host::stop aborts running broker and cargo requests first
- compile a version before installing it; roll back if it does not start
- unique archive names; a failed archive keeps the actor manageable
- commit on close: truncate without create; directory renames
- candidates see SAUSAGE_VERSION and the existing state of a new actor
- the host publishes PROTOCOL.md at /actor/broker/public/

cli/tests/common/mod.rs

@@ -142,6 +142,28 @@ pub async fn receive_reply(
     .unwrap_or_else(|_| panic!("timed out waiting for reply to {id}"))
 }
 
+pub async fn receive_replies(
+    mailbox: &mut mpsc::Receiver<Envelope>,
+    ids: &[String],
+    timeout: Duration,
+) -> Vec<Envelope> {
+    let mut replies = Vec::with_capacity(ids.len());
+    tokio::time::timeout(timeout, async {
+        while replies.len() < ids.len() {
+            let message = mailbox.recv().await.expect("console mailbox closed");
+            assert!(
+                ids.iter()
+                    .any(|id| message.reply_to.as_deref() == Some(id.as_str())),
+                "unexpected message while waiting for replies: {message:?}"
+            );
+            replies.push(message);
+        }
+    })
+    .await
+    .expect("timed out waiting for replies");
+    replies
+}
+
 pub async fn ask(
     host: &Host,
     mailbox: &mut mpsc::Receiver<Envelope>,
@@ -152,16 +174,24 @@ pub async fn ask(
     receive_reply(mailbox, &id, REPLY_TIMEOUT).await
 }
 
-pub async fn spawn_actor(
+pub async fn ask_type(
     host: &Host,
     mailbox: &mut mpsc::Receiver<Envelope>,
     actor: &str,
-    wasm: &Path,
-    source: &Path,
+    body: Value,
+    expected: &str,
 ) -> Envelope {
-    request(
-        host,
-        mailbox,
+    let reply = ask(host, mailbox, actor, body).await;
+    assert_eq!(reply.body["type"], expected, "unexpected reply: {reply:?}");
+    reply
+}
+
+pub fn spawn_request(host: &Host, actor: &str, wasm: &Path, source: &Path) -> String {
+    host.broker.send(
+        "console",
+        Some("broker"),
+        None,
+        None,
         json!({
             "type": "spawn",
             "actor": actor,
@@ -169,7 +199,32 @@ pub async fn spawn_actor(
             "source": source.display().to_string()
         }),
     )
-    .await
+}
+
+pub async fn spawn_actor(
+    host: &Host,
+    mailbox: &mut mpsc::Receiver<Envelope>,
+    actor: &str,
+    wasm: &Path,
+    source: &Path,
+) -> Envelope {
+    let id = spawn_request(host, actor, wasm, source);
+    receive_reply(mailbox, &id, REPLY_TIMEOUT).await
+}
+
+pub async fn spawn_type(
+    host: &Host,
+    mailbox: &mut mpsc::Receiver<Envelope>,
+    actor: &str,
+    wasm: &Path,
+    source: &Path,
+) -> Envelope {
+    let reply = spawn_actor(host, mailbox, actor, wasm, source).await;
+    assert_eq!(
+        reply.body["type"], "spawned",
+        "unexpected spawn reply: {reply:?}"
+    );
+    reply
 }
 
 pub async fn upgrade_actor(