diff --git a/crates/ty_server/src/server/api/diagnostics.rs b/crates/ty_server/src/server/api/diagnostics.rs
index 56a85a0cd7ef83..c687b65fd8e2fb 100644
--- a/crates/ty_server/src/server/api/diagnostics.rs
+++ b/crates/ty_server/src/server/api/diagnostics.rs
@@ -24,6 +24,7 @@ use crate::system::{AnySystemPath, file_to_url};
 use crate::{DIAGNOSTIC_NAME, Db, DiagnosticMode};
 use crate::{PositionEncoding, Session};
 
+#[derive(Debug)]
 pub(super) struct Diagnostics {
     items: Vec<ruff_db::diagnostic::Diagnostic>,
     encoding: PositionEncoding,
diff --git a/crates/ty_server/src/server/api/notifications/did_open.rs b/crates/ty_server/src/server/api/notifications/did_open.rs
index 942c1a193b49b0..c47b2854552293 100644
--- a/crates/ty_server/src/server/api/notifications/did_open.rs
+++ b/crates/ty_server/src/server/api/notifications/did_open.rs
@@ -2,6 +2,7 @@ use lsp_types::notification::DidOpenTextDocument;
 use lsp_types::{DidOpenTextDocumentParams, TextDocumentItem};
 
 use crate::TextDocument;
+use crate::document::LanguageId;
 use crate::server::Result;
 use crate::server::api::diagnostics::publish_diagnostics_if_needed;
 use crate::server::api::traits::{NotificationHandler, SyncNotificationHandler};
@@ -30,10 +31,12 @@ impl SyncNotificationHandler for DidOpenTextDocumentHandler {
                 },
         } = params;
 
-        let document = session.open_text_document(
-            TextDocument::new(uri, text, version).with_language_id(&language_id),
-        );
+        let text_doc = TextDocument::new(uri, text, version).with_language_id(&language_id);
+        if matches!(text_doc.language_id(), Some(LanguageId::Other)) {
+            return Ok(());
+        }
 
+        let document = session.open_text_document(text_doc);
         publish_diagnostics_if_needed(&document, session, client);
 
         Ok(())
diff --git a/crates/ty_server/src/session.rs b/crates/ty_server/src/session.rs
index d30e2e2a8018ec..764825740e3f7f 100644
--- a/crates/ty_server/src/session.rs
+++ b/crates/ty_server/src/session.rs
@@ -24,7 +24,7 @@ use ruff_python_ast::PySourceType;
 use ty_combine::Combine;
 use ty_project::metadata::Options;
 use ty_project::watch::{ChangeEvent, CreatedKind};
-use ty_project::{ChangeResult, CheckMode, Db as _, ProjectDatabase, ProjectMetadata};
+use ty_project::{ChangeResult, Db as _, ProjectDatabase, ProjectMetadata};
 
 use index::DocumentError;
 use ty_python_semantic::MisconfigurationMode;
@@ -530,13 +530,13 @@ impl Session {
 
         if let Some(global_options) = global_options {
             let global_settings = global_options.into_settings();
-            if global_settings.diagnostic_mode().is_workspace() {
-                for project in self.projects.values_mut() {
-                    project.db.set_check_mode(CheckMode::AllFiles);
-                }
-            }
             self.global_settings = Arc::new(global_settings);
         }
+        if let Some(check_mode) = self.global_settings.diagnostic_mode().to_check_mode() {
+            for project in self.projects.values_mut() {
+                project.db.set_check_mode(check_mode);
+            }
+        }
 
         self.register_capabilities(client);
     }
diff --git a/crates/ty_server/src/session/options.rs b/crates/ty_server/src/session/options.rs
index cafd80a5735a32..1abcafdebd15f1 100644
--- a/crates/ty_server/src/session/options.rs
+++ b/crates/ty_server/src/session/options.rs
@@ -8,6 +8,7 @@ use serde::{Deserialize, Serialize};
 use serde_json::{Map, Value};
 use ty_combine::Combine;
 use ty_ide::{CompletionSettings, InlayHintSettings};
+use ty_project::CheckMode;
 use ty_project::metadata::Options as TyOptions;
 use ty_project::metadata::options::ProjectOptionsOverrides;
 use ty_project::metadata::value::{RangedValue, RelativePathBuf, ValueSource};
@@ -369,6 +370,17 @@ impl DiagnosticMode {
         matches!(self, DiagnosticMode::OpenFilesOnly)
     }
 
+    /// Returns this diagnostic mode as a check mode.
+    ///
+    /// This returns `None` when diagnostics are disabled.
+    pub(crate) const fn to_check_mode(self) -> Option<CheckMode> {
+        match self {
+            DiagnosticMode::Off => None,
+            DiagnosticMode::OpenFilesOnly => Some(CheckMode::OpenFiles),
+            DiagnosticMode::Workspace => Some(CheckMode::AllFiles),
+        }
+    }
+
     pub(crate) const fn is_off(self) -> bool {
         matches!(self, DiagnosticMode::Off)
     }
diff --git a/crates/ty_server/tests/e2e/publish_diagnostics.rs b/crates/ty_server/tests/e2e/publish_diagnostics.rs
index 6c4be0c25ba0cf..1d0077c1a122d2 100644
--- a/crates/ty_server/tests/e2e/publish_diagnostics.rs
+++ b/crates/ty_server/tests/e2e/publish_diagnostics.rs
@@ -326,8 +326,6 @@ def foo() -> str:
         },
     };
     server.send_notification::<DidOpenTextDocument>(params);
-    let _close_diagnostics = server.await_notification::<PublishDiagnostics>();
-
     let diagnostics = server.await_notification::<PublishDiagnostics>();
 
     insta::assert_debug_snapshot!(diagnostics);
diff --git a/crates/ty_server/tests/e2e/snapshots/e2e__publish_diagnostics__changing_language_of_file_without_extension-2.snap b/crates/ty_server/tests/e2e/snapshots/e2e__publish_diagnostics__changing_language_of_file_without_extension-2.snap
index 91a4a10b81dc0a..f29237130921a3 100644
--- a/crates/ty_server/tests/e2e/snapshots/e2e__publish_diagnostics__changing_language_of_file_without_extension-2.snap
+++ b/crates/ty_server/tests/e2e/snapshots/e2e__publish_diagnostics__changing_language_of_file_without_extension-2.snap
@@ -15,7 +15,5 @@ PublishDiagnosticsParams {
         fragment: None,
     },
     diagnostics: [],
-    version: Some(
-        1,
-    ),
+    version: None,
 }