Expose advertised actor-served files in directory listings

cli/tests/host.rs

@@ -246,6 +246,71 @@ async fn actors_serve_files_under_fs() {
     host.stop().await;
 }
 
+#[tokio::test]
+async fn actor_fs_is_discoverable_only_when_its_source_docs_advertise_it() {
+    let world = create_world("actor-fs-discovery");
+    let wasm = toolbox_wasm().clone();
+    let (host, mut mailbox) = start(&world).await;
+
+    let advertised = passing_source(&world, "advertised-fs");
+    std::fs::create_dir_all(advertised.join("src")).unwrap();
+    std::fs::write(
+        advertised.join("src/main.rs"),
+        "//! test actor\n//! Actor-served files: implements fs_read and fs_dir.\n",
+    )
+    .unwrap();
+    spawn_type(&host, &mut mailbox, "served", &wasm, &advertised).await;
+
+    let undocumented = passing_source(&world, "undocumented-fs");
+    std::fs::create_dir_all(undocumented.join("src")).unwrap();
+    std::fs::write(undocumented.join("src/main.rs"), "//! test actor without a virtual filesystem\n").unwrap();
+    spawn_type(&host, &mut mailbox, "plain", &wasm, &undocumented).await;
+
+    let reader_source = passing_source(&world, "fs-reader");
+    spawn_type(&host, &mut mailbox, "reader", &wasm, &reader_source).await;
+
+    let served_entries = ask_type(
+        &host,
+        &mut mailbox,
+        "reader",
+        json!({"type": "list", "path": "/actor/served"}),
+        "entries",
+    )
+    .await;
+    assert!(served_entries.body["names"].as_array().unwrap().iter().any(|name| name.as_str() == Some("fs")));
+
+    let plain_entries = ask_type(
+        &host,
+        &mut mailbox,
+        "reader",
+        json!({"type": "list", "path": "/actor/plain"}),
+        "entries",
+    )
+    .await;
+    assert!(!plain_entries.body["names"].as_array().unwrap().iter().any(|name| name.as_str() == Some("fs")));
+
+    let path = "/actor/served/fs/docs/readme.txt";
+    ask_type(
+        &host,
+        &mut mailbox,
+        "reader",
+        json!({"type": "write", "path": path, "text": "virtual document"}),
+        "ok",
+    )
+    .await;
+    let document = ask_type(
+        &host,
+        &mut mailbox,
+        "reader",
+        json!({"type": "read", "path": path}),
+        "content",
+    )
+    .await;
+    assert_eq!(document.body["text"], "virtual document");
+
+    host.stop().await;
+}
+
 #[tokio::test]
 async fn files_are_plain_posix_files() {
     let (_, host, mut mailbox) = filesystem_world("posix").await;