diff --git a/crates/worker/src/spawn/tool.rs b/crates/worker/src/spawn/tool.rs
index 49b1fe61..af8c69be 100644
--- a/crates/worker/src/spawn/tool.rs
+++ b/crates/worker/src/spawn/tool.rs
@@ -1850,7 +1850,7 @@ max_tokens = 3333
     }
 
     #[test]
-    fn invalid_ambiguous_and_no_default_diagnostics_include_available_selectors() {
+    fn invalid_and_ambiguous_diagnostics_include_available_selectors() {
         let tmp = TempDir::new().unwrap();
         let project = tmp.path().join("project");
         std::fs::create_dir_all(&project).unwrap();
@@ -1868,17 +1868,21 @@ max_tokens = 3333
         assert!(invalid.contains("Use `default`, `inherit`"));
         assert!(invalid.contains("`project:coder`"));
 
-        let default_error = build_spawn_config_json_for_profile(
-            &parent,
-            &available,
-            &project,
-            "child",
-            None,
-            &scope,
-            SpawnProfileSelector::Default,
+        let default_config: serde_json::Value = serde_json::from_str(
+            &build_spawn_config_json_for_profile(
+                &parent,
+                &available,
+                &project,
+                "child",
+                None,
+                &scope,
+                SpawnProfileSelector::Default,
+            )
+            .unwrap(),
         )
-        .unwrap_err();
-        assert!(default_error.contains("no default profile is configured"));
+        .unwrap();
+        assert_eq!(default_config["feature"]["sub_worker"]["enabled"], true);
+        assert_eq!(default_config["feature"]["ticket"]["enabled"], false);
 
         let user_config = tmp.path().join("user-profiles.toml");
         std::fs::write(&user_config, "[profile]\ncoder = \"user-coder.toml\"\n").unwrap();
diff --git a/crates/workspace-server/src/hosts.rs b/crates/workspace-server/src/hosts.rs
index 9e63f151..05ac7f46 100644
--- a/crates/workspace-server/src/hosts.rs
+++ b/crates/workspace-server/src/hosts.rs
@@ -3740,7 +3740,13 @@ fn builtin_profile_source_archive(
     profile: &ProfileSelector,
 ) -> Result<ProfileSourceArchive, String> {
     let selected_profile = match profile {
-        ProfileSelector::Builtin(name) => name.clone(),
+        ProfileSelector::Builtin(name) => {
+            if name.starts_with("builtin:") {
+                name.clone()
+            } else {
+                format!("builtin:{name}")
+            }
+        }
         ProfileSelector::Named(name) => {
             return Err(format!(
                 "embedded runtime does not provide named Profile `{name}`"
diff --git a/crates/workspace-server/src/server.rs b/crates/workspace-server/src/server.rs
index bb0263d7..69626ada 100644
--- a/crates/workspace-server/src/server.rs
+++ b/crates/workspace-server/src/server.rs
@@ -18155,7 +18155,12 @@ mod tests {
                 },
             )
             .unwrap();
-        assert_eq!(existing.state, WorkerOperationState::Accepted);
+        assert_eq!(
+            existing.state,
+            WorkerOperationState::Accepted,
+            "diagnostics: {:?}",
+            existing.diagnostics
+        );
         let worker_id = existing.worker.unwrap().worker.worker_id;
         let worker = api
             .runtime