fix: surface rejected configuration in a floating startup diagnostic

src/session.rs

@@ -46,8 +46,8 @@ pub struct EditorSession {
 }
 
 impl EditorSession {
-    /// File errors fail opening; config and plugin errors leave core editing
-    /// available and are reported in the editor's message.
+    /// File errors fail opening; rejected configuration leaves core editing
+    /// available and presents a persistent startup diagnostic.
     pub fn open(
         file: Option<PathBuf>,
         capabilities: Vec<String>,
@@ -57,7 +57,10 @@ impl EditorSession {
         let mut notices = Vec::new();
         let config = match config {
             Some(path) => load_config(path).unwrap_or_else(|error| {
-                notices.push(format!("config disabled: {error}"));
+                editor.show_startup_diagnostic(format!(
+                    "{}\n\nConfiguration was rejected; using default settings and bindings.\n\n{error}",
+                    path.display()
+                ));
                 Config::default()
             }),
             None => Config::default(),
@@ -2317,7 +2320,17 @@ end
             let mut session = fixture.open(&format!(
                 "Vamp.configure do |config|\n  config.leader = \",\"\n  config.bind \"i\", nil\n  {expression}\nend"
             ));
-            assert!(session.editor().message().contains(error), "{expression}");
+            assert!(
+                session
+                    .editor()
+                    .startup_diagnostic()
+                    .unwrap()
+                    .lines
+                    .iter()
+                    .any(|line| line.contains(error)),
+                "{expression}"
+            );
+            session.handle(Input::Enter);
             session.handle(Input::Char('i'));
             session.handle(Input::Char('界'));
             session.handle(Input::Escape);
@@ -2338,24 +2351,56 @@ end
     }
 
     #[test]
-    fn broken_config_falls_back_to_core_without_failing_the_session() {
-        let fixture = Fixture::new();
-        let mut session = fixture.open("raise 'broken config'");
-        assert!(
-            session
+    fn rejected_config_diagnostic_persists_until_dismissed_and_default_editing_survives() {
+        for (config, reason, dismiss) in [
+            ("raise 'broken config'", "broken config", Input::Enter),
+            (
+                "Vamp.configure { |config| config.lsp['ruby'] = true }",
+                "ruby",
+                Input::Escape,
+            ),
+        ] {
+            let fixture = Fixture::new();
+            let mut session = fixture.open(config);
+            let diagnostic = session
                 .editor()
-                .message()
-                .contains("config disabled: Ruby config: RuntimeError: broken config")
-        );
-        session.handle(Input::Char('i'));
-        session.handle(Input::Char('x'));
-        session.handle(Input::Escape);
-        session.execute("wq");
-        assert!(session.editor().should_quit());
-        assert_eq!(
-            fs::read_to_string(fixture.0.join("buffer.txt")).unwrap(),
-            "x"
-        );
+                .startup_diagnostic()
+                .expect("config failure must be visible");
+            let text = diagnostic.lines.join("\n");
+            assert!(text.contains(&fixture.0.join("config.rb").display().to_string()));
+            assert!(text.contains(reason));
+            session.editor.set_message("unrelated background message");
+            session.poll();
+            for input in [
+                Input::Char('i'),
+                Input::Paste("accidental edit".into()),
+                Input::Ctrl('p'),
+            ] {
+                session.handle(input);
+            }
+            assert_eq!(
+                session
+                    .editor()
+                    .startup_diagnostic()
+                    .unwrap()
+                    .lines
+                    .join("\n"),
+                text
+            );
+            assert_eq!(session.editor().mode(), Mode::Normal);
+            assert_eq!(session.editor().lines(), &[""]);
+            session.handle(dismiss);
+            assert!(session.editor().startup_diagnostic().is_none());
+            session.handle(Input::Char('i'));
+            session.handle(Input::Char('x'));
+            session.handle(Input::Escape);
+            session.execute("wq");
+            assert!(session.editor().should_quit());
+            assert_eq!(
+                fs::read_to_string(fixture.0.join("buffer.txt")).unwrap(),
+                "x"
+            );
+        }
     }
 
     fn drain_until(session: &mut EditorSession, ready: impl Fn(&EditorSession) -> bool) {