diff --git a/cli/lsp/tsc.rs b/cli/lsp/tsc.rs
index e45d6d52b4..e6a1614746 100644
--- a/cli/lsp/tsc.rs
+++ b/cli/lsp/tsc.rs
@@ -93,7 +93,7 @@ const FILE_EXTENSION_KIND_MODIFIERS: &[&str] =
   &[".d.ts", ".ts", ".tsx", ".js", ".jsx", ".json"];
 
 type Request = (
-  RequestMethod,
+  TscRequest,
   Arc<StateSnapshot>,
   oneshot::Sender<Result<Value, AnyError>>,
   CancellationToken,
@@ -149,7 +149,7 @@ pub struct TsServer {
 
 impl TsServer {
   pub fn new(performance: Arc<Performance>, cache: Arc<dyn HttpCache>) -> Self {
-    let specifier_map = Arc::new(TscSpecifierMap::default());
+    let specifier_map = Arc::new(TscSpecifierMap::new());
     let specifier_map_ = specifier_map.clone();
     let (tx, mut rx) = mpsc::unbounded_channel::<Request>();
     let _join_handle = thread::spawn(move || {
@@ -184,7 +184,13 @@ impl TsServer {
     specifiers: Vec<ModuleSpecifier>,
     token: CancellationToken,
   ) -> Result<HashMap<String, Vec<crate::tsc::Diagnostic>>, AnyError> {
-    let req = RequestMethod::GetDiagnostics(specifiers);
+    let req = TscRequest {
+      method: "$getDiagnostics",
+      args: json!([specifiers
+        .into_iter()
+        .map(|s| self.specifier_map.denormalize(&s))
+        .collect::<Vec<String>>(),]),
+    };
     let diagnostics_map_ = self.request_with_cancellation::<HashMap<String, Vec<crate::tsc::Diagnostic>>>(snapshot, req, token).await?;
     let mut diagnostics_map = HashMap::new();
     for (mut specifier, mut diagnostics) in diagnostics_map_ {
@@ -203,9 +209,10 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Option<Vec<ReferencedSymbol>>, LspError> {
-    let req = RequestMethod::FindReferences {
-      specifier,
-      position,
+    let req = TscRequest {
+      method: "findReferences",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6230
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
     };
     self
       .request::<Option<Vec<ReferencedSymbol>>>(snapshot, req)
@@ -227,9 +234,12 @@ impl TsServer {
     snapshot: Arc<StateSnapshot>,
     specifier: ModuleSpecifier,
   ) -> Result<NavigationTree, AnyError> {
-    self
-      .request(snapshot, RequestMethod::GetNavigationTree(specifier))
-      .await
+    let req = TscRequest {
+      method: "getNavigationTree",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6235
+      args: json!([self.specifier_map.denormalize(&specifier)]),
+    };
+    self.request(snapshot, req).await
   }
 
   pub async fn configure(
@@ -237,22 +247,25 @@ impl TsServer {
     snapshot: Arc<StateSnapshot>,
     tsconfig: TsConfig,
   ) -> Result<bool, AnyError> {
-    self
-      .request(snapshot, RequestMethod::Configure(tsconfig))
-      .await
+    let req = TscRequest {
+      method: "$configure",
+      args: json!([tsconfig]),
+    };
+    self.request(snapshot, req).await
   }
 
   pub async fn get_supported_code_fixes(
     &self,
     snapshot: Arc<StateSnapshot>,
   ) -> Result<Vec<String>, LspError> {
-    self
-      .request(snapshot, RequestMethod::GetSupportedCodeFixes)
-      .await
-      .map_err(|err| {
-        log::error!("Unable to get fixable diagnostics: {}", err);
-        LspError::internal_error()
-      })
+    let req = TscRequest {
+      method: "$getSupportedCodeFixes",
+      args: json!([]),
+    };
+    self.request(snapshot, req).await.map_err(|err| {
+      log::error!("Unable to get fixable diagnostics: {}", err);
+      LspError::internal_error()
+    })
   }
 
   pub async fn get_quick_info(
@@ -261,7 +274,11 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Option<QuickInfo>, LspError> {
-    let req = RequestMethod::GetQuickInfo((specifier, position));
+    let req = TscRequest {
+      method: "getQuickInfoAtPosition",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6214
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
+    };
     self.request(snapshot, req).await.map_err(|err| {
       log::error!("Unable to get quick info: {}", err);
       LspError::internal_error()
@@ -277,14 +294,21 @@ impl TsServer {
     format_code_settings: FormatCodeSettings,
     preferences: UserPreferences,
   ) -> Vec<CodeFixAction> {
-    let req = RequestMethod::GetCodeFixes((
-      specifier,
-      range.start,
-      range.end,
-      codes,
-      format_code_settings,
-      preferences,
-    ));
+    let mut format_code_settings = json!(format_code_settings);
+    let format_object = format_code_settings.as_object_mut().unwrap();
+    format_object.insert("indentStyle".to_string(), json!(1));
+    let req = TscRequest {
+      method: "getCodeFixesAtPosition",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6257
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        range.start,
+        range.end,
+        codes,
+        format_code_settings,
+        preferences,
+      ]),
+    };
     let result = self
       .request::<Vec<CodeFixAction>>(snapshot, req)
       .await
@@ -315,15 +339,17 @@ impl TsServer {
     preferences: Option<UserPreferences>,
     only: String,
   ) -> Result<Vec<ApplicableRefactorInfo>, LspError> {
-    let req = RequestMethod::GetApplicableRefactors((
-      specifier.clone(),
-      TextSpan {
-        start: range.start,
-        length: range.end - range.start,
-      },
-      preferences,
-      only,
-    ));
+    let req = TscRequest {
+      method: "getApplicableRefactors",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6274
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        { "pos": range.start, "end": range.end },
+        preferences.unwrap_or_default(),
+        json!(null),
+        only,
+      ]),
+    };
     self.request(snapshot, req).await.map_err(|err| {
       log::error!("Failed to request to tsserver {}", err);
       LspError::invalid_request()
@@ -337,12 +363,22 @@ impl TsServer {
     format_code_settings: FormatCodeSettings,
     preferences: UserPreferences,
   ) -> Result<CombinedCodeActions, LspError> {
-    let req = RequestMethod::GetCombinedCodeFix((
-      code_action_data.specifier.clone(),
-      json!(code_action_data.fix_id.clone()),
-      format_code_settings,
-      preferences,
-    ));
+    let mut format_code_settings = json!(format_code_settings);
+    let format_object = format_code_settings.as_object_mut().unwrap();
+    format_object.insert("indentStyle".to_string(), json!(1));
+    let req = TscRequest {
+      method: "getCombinedCodeFix",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6258
+      args: json!([
+        {
+          "type": "file",
+          "fileName": self.specifier_map.denormalize(&code_action_data.specifier),
+        },
+        &code_action_data.fix_id,
+        format_code_settings,
+        preferences,
+      ]),
+    };
     self
       .request::<CombinedCodeActions>(snapshot, req)
       .await
@@ -367,17 +403,27 @@ impl TsServer {
     action_name: String,
     preferences: Option<UserPreferences>,
   ) -> Result<RefactorEditInfo, LspError> {
-    let req = RequestMethod::GetEditsForRefactor((
-      specifier,
-      format_code_settings,
-      TextSpan {
-        start: range.start,
-        length: range.end - range.start,
-      },
-      refactor_name,
-      action_name,
-      preferences,
-    ));
+    let mut format_code_settings = json!(format_code_settings);
+    let format_object = format_code_settings.as_object_mut().unwrap();
+    format_object.insert("indentStyle".to_string(), json!(2));
+    format_object.insert(
+      "insertSpaceBeforeAndAfterBinaryOperators".to_string(),
+      json!(true),
+    );
+    format_object
+      .insert("insertSpaceAfterCommaDelimiter".to_string(), json!(true));
+    let req = TscRequest {
+      method: "getEditsForRefactor",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6275
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        format_code_settings,
+        { "pos": range.start, "end": range.end },
+        refactor_name,
+        action_name,
+        preferences,
+      ]),
+    };
     self
       .request::<RefactorEditInfo>(snapshot, req)
       .await
@@ -399,12 +445,16 @@ impl TsServer {
     format_code_settings: FormatCodeSettings,
     user_preferences: UserPreferences,
   ) -> Result<Vec<FileTextChanges>, LspError> {
-    let req = RequestMethod::GetEditsForFileRename((
-      old_specifier,
-      new_specifier,
-      format_code_settings,
-      user_preferences,
-    ));
+    let req = TscRequest {
+      method: "getEditsForFileRename",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6281
+      args: json!([
+        self.specifier_map.denormalize(&old_specifier),
+        self.specifier_map.denormalize(&new_specifier),
+        format_code_settings,
+        user_preferences,
+      ]),
+    };
     self
       .request::<Vec<FileTextChanges>>(snapshot, req)
       .await
@@ -427,11 +477,18 @@ impl TsServer {
     position: u32,
     files_to_search: Vec<ModuleSpecifier>,
   ) -> Result<Option<Vec<DocumentHighlights>>, LspError> {
-    let req = RequestMethod::GetDocumentHighlights((
-      specifier,
-      position,
-      files_to_search,
-    ));
+    let req = TscRequest {
+      method: "getDocumentHighlights",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6231
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        position,
+        files_to_search
+          .into_iter()
+          .map(|s| self.specifier_map.denormalize(&s))
+          .collect::<Vec<_>>(),
+      ]),
+    };
     self.request(snapshot, req).await.map_err(|err| {
       log::error!("Unable to get document highlights from TypeScript: {}", err);
       LspError::internal_error()
@@ -444,7 +501,11 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Option<DefinitionInfoAndBoundSpan>, LspError> {
-    let req = RequestMethod::GetDefinition((specifier, position));
+    let req = TscRequest {
+      method: "getDefinitionAndBoundSpan",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6226
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
+    };
     self
       .request::<Option<DefinitionInfoAndBoundSpan>>(snapshot, req)
       .await
@@ -466,9 +527,10 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Option<Vec<DefinitionInfo>>, LspError> {
-    let req = RequestMethod::GetTypeDefinition {
-      specifier,
-      position,
+    let req = TscRequest {
+      method: "getTypeDefinitionAtPosition",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6227
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
     };
     self
       .request::<Option<Vec<DefinitionInfo>>>(snapshot, req)
@@ -493,12 +555,16 @@ impl TsServer {
     options: GetCompletionsAtPositionOptions,
     format_code_settings: FormatCodeSettings,
   ) -> Option<CompletionInfo> {
-    let req = RequestMethod::GetCompletions((
-      specifier,
-      position,
-      options,
-      format_code_settings,
-    ));
+    let req = TscRequest {
+      method: "getCompletionsAtPosition",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6193
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        position,
+        options,
+        format_code_settings,
+      ]),
+    };
     match self.request(snapshot, req).await {
       Ok(maybe_info) => maybe_info,
       Err(err) => {
@@ -513,7 +579,19 @@ impl TsServer {
     snapshot: Arc<StateSnapshot>,
     args: GetCompletionDetailsArgs,
   ) -> Result<Option<CompletionEntryDetails>, AnyError> {
-    let req = RequestMethod::GetCompletionDetails(args);
+    let req = TscRequest {
+      method: "getCompletionEntryDetails",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6205
+      args: json!([
+        self.specifier_map.denormalize(&args.specifier),
+        args.position,
+        args.name,
+        args.format_code_settings.unwrap_or_default(),
+        args.source,
+        args.preferences,
+        args.data,
+      ]),
+    };
     self
       .request::<Option<CompletionEntryDetails>>(snapshot, req)
       .await
@@ -531,7 +609,11 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Option<Vec<ImplementationLocation>>, LspError> {
-    let req = RequestMethod::GetImplementation((specifier, position));
+    let req = TscRequest {
+      method: "getImplementationAtPosition",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6228
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
+    };
     self
       .request::<Option<Vec<ImplementationLocation>>>(snapshot, req)
       .await
@@ -552,7 +634,11 @@ impl TsServer {
     snapshot: Arc<StateSnapshot>,
     specifier: ModuleSpecifier,
   ) -> Result<Vec<OutliningSpan>, LspError> {
-    let req = RequestMethod::GetOutliningSpans(specifier);
+    let req = TscRequest {
+      method: "getOutliningSpans",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6240
+      args: json!([self.specifier_map.denormalize(&specifier)]),
+    };
     self.request(snapshot, req).await.map_err(|err| {
       log::error!("Failed to request to tsserver {}", err);
       LspError::invalid_request()
@@ -565,8 +651,11 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Vec<CallHierarchyIncomingCall>, LspError> {
-    let req =
-      RequestMethod::ProvideCallHierarchyIncomingCalls((specifier, position));
+    let req = TscRequest {
+      method: "provideCallHierarchyIncomingCalls",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6237
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
+    };
     self
       .request::<Vec<CallHierarchyIncomingCall>>(snapshot, req)
       .await
@@ -588,8 +677,11 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Vec<CallHierarchyOutgoingCall>, LspError> {
-    let req =
-      RequestMethod::ProvideCallHierarchyOutgoingCalls((specifier, position));
+    let req = TscRequest {
+      method: "provideCallHierarchyOutgoingCalls",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6238
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
+    };
     self
       .request::<Vec<CallHierarchyOutgoingCall>>(snapshot, req)
       .await
@@ -611,7 +703,11 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Option<OneOrMany<CallHierarchyItem>>, LspError> {
-    let req = RequestMethod::PrepareCallHierarchy((specifier, position));
+    let req = TscRequest {
+      method: "prepareCallHierarchy",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6236
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
+    };
     self
       .request::<Option<OneOrMany<CallHierarchyItem>>>(snapshot, req)
       .await
@@ -641,12 +737,16 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<Option<Vec<RenameLocation>>, LspError> {
-    let req = RequestMethod::FindRenameLocations {
-      specifier,
-      position,
-      find_in_strings: false,
-      find_in_comments: false,
-      provide_prefix_and_suffix_text_for_rename: false,
+    let req = TscRequest {
+      method: "findRenameLocations",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6221
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        position,
+        false,
+        false,
+        false,
+      ]),
     };
     self
       .request::<Option<Vec<RenameLocation>>>(snapshot, req)
@@ -669,8 +769,11 @@ impl TsServer {
     specifier: ModuleSpecifier,
     position: u32,
   ) -> Result<SelectionRange, LspError> {
-    let req = RequestMethod::GetSmartSelectionRange((specifier, position));
-
+    let req = TscRequest {
+      method: "getSmartSelectionRange",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6224
+      args: json!([self.specifier_map.denormalize(&specifier), position]),
+    };
     self.request(snapshot, req).await.map_err(|err| {
       log::error!("Failed to request to tsserver {}", err);
       LspError::invalid_request()
@@ -683,13 +786,18 @@ impl TsServer {
     specifier: ModuleSpecifier,
     range: Range<u32>,
   ) -> Result<Classifications, LspError> {
-    let req = RequestMethod::GetEncodedSemanticClassifications((
-      specifier,
-      TextSpan {
-        start: range.start,
-        length: range.end - range.start,
-      },
-    ));
+    let req = TscRequest {
+      method: "getEncodedSemanticClassifications",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6183
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        TextSpan {
+          start: range.start,
+          length: range.end - range.start,
+        },
+        "2020",
+      ]),
+    };
     self.request(snapshot, req).await.map_err(|err| {
       log::error!("Failed to request to tsserver {}", err);
       LspError::invalid_request()
@@ -703,8 +811,15 @@ impl TsServer {
     position: u32,
     options: SignatureHelpItemsOptions,
   ) -> Result<Option<SignatureHelpItems>, LspError> {
-    let req =
-      RequestMethod::GetSignatureHelpItems((specifier, position, options));
+    let req = TscRequest {
+      method: "getSignatureHelpItems",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6217
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        position,
+        options,
+      ]),
+    };
     self.request(snapshot, req).await.map_err(|err| {
       log::error!("Failed to request to tsserver: {}", err);
       LspError::invalid_request()
@@ -716,7 +831,18 @@ impl TsServer {
     snapshot: Arc<StateSnapshot>,
     args: GetNavigateToItemsArgs,
   ) -> Result<Vec<NavigateToItem>, LspError> {
-    let req = RequestMethod::GetNavigateToItems(args);
+    let req = TscRequest {
+      method: "getNavigateToItems",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6233
+      args: json!([
+        args.search,
+        args.max_result_count,
+        args.file.map(|f| match resolve_url(&f) {
+          Ok(s) => self.specifier_map.denormalize(&s),
+          Err(_) => f,
+        }),
+      ]),
+    };
     self
       .request::<Vec<NavigateToItem>>(snapshot, req)
       .await
@@ -739,11 +865,15 @@ impl TsServer {
     text_span: TextSpan,
     user_preferences: UserPreferences,
   ) -> Result<Option<Vec<InlayHint>>, LspError> {
-    let req = RequestMethod::ProvideInlayHints((
-      specifier,
-      text_span,
-      user_preferences,
-    ));
+    let req = TscRequest {
+      method: "provideInlayHints",
+      // https://github.com/denoland/deno/blob/v1.37.1/cli/tsc/dts/typescript.d.ts#L6239
+      args: json!([
+        self.specifier_map.denormalize(&specifier),
+        text_span,
+        user_preferences,
+      ]),
+    };
     self.request(snapshot, req).await.map_err(|err| {
       log::error!("Unable to get inlay hints: {}", err);
       LspError::internal_error()
@@ -751,16 +881,17 @@ impl TsServer {
   }
 
   pub async fn restart(&self, snapshot: Arc<StateSnapshot>) {
-    let _: bool = self
-      .request(snapshot, RequestMethod::Restart)
-      .await
-      .unwrap();
+    let req = TscRequest {
+      method: "$restart",
+      args: json!([]),
+    };
+    self.request::<bool>(snapshot, req).await.unwrap();
   }
 
   async fn request<R>(
     &self,
     snapshot: Arc<StateSnapshot>,
-    req: RequestMethod,
+    req: TscRequest,
   ) -> Result<R, AnyError>
   where
     R: de::DeserializeOwned,
@@ -773,7 +904,7 @@ impl TsServer {
   async fn request_with_cancellation<R>(
     &self,
     snapshot: Arc<StateSnapshot>,
-    req: RequestMethod,
+    req: TscRequest,
     token: CancellationToken,
   ) -> Result<R, AnyError>
   where
@@ -930,10 +1061,11 @@ async fn get_isolate_assets(
   ts_server: &TsServer,
   state_snapshot: Arc<StateSnapshot>,
 ) -> Vec<AssetDocument> {
-  let res: Value = ts_server
-    .request(state_snapshot, RequestMethod::GetAssets)
-    .await
-    .unwrap();
+  let req = TscRequest {
+    method: "$getAssets",
+    args: json!([]),
+  };
+  let res: Value = ts_server.request(state_snapshot, req).await.unwrap();
   let response_assets = match res {
     Value::Array(value) => value,
     _ => unreachable!(),
@@ -1277,6 +1409,7 @@ pub struct SymbolDisplayPart {
   // This is only on `JSDocLinkDisplayPart` which extends `SymbolDisplayPart`
   // but is only used as an upcast of a `SymbolDisplayPart` and not explicitly
   // returned by any API, so it is safe to add it as an optional value.
+  #[serde(skip_serializing_if = "Option::is_none")]
   target: Option<DocumentSpan>,
 }
 
@@ -1442,7 +1575,7 @@ pub struct DocumentSpan {
 }
 
 impl DocumentSpan {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -1457,7 +1590,7 @@ impl DocumentSpan {
     line_index: Arc<LineIndex>,
     language_server: &language_server::Inner,
   ) -> Option<lsp::LocationLink> {
-    let target_specifier = normalize_specifier(&self.file_name).ok()?;
+    let target_specifier = resolve_url(&self.file_name).ok()?;
     let target_asset_or_doc =
       language_server.get_maybe_asset_or_document(&target_specifier)?;
     let target_line_index = target_asset_or_doc.line_index();
@@ -1502,7 +1635,7 @@ impl DocumentSpan {
     &self,
     language_server: &language_server::Inner,
   ) -> Option<ModuleSpecifier> {
-    let specifier = normalize_specifier(&self.file_name).ok()?;
+    let specifier = resolve_url(&self.file_name).ok()?;
     let asset_or_doc =
       language_server.get_maybe_asset_or_document(&specifier)?;
     let line_index = asset_or_doc.line_index();
@@ -1549,7 +1682,7 @@ pub struct NavigateToItem {
 }
 
 impl NavigateToItem {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -1563,7 +1696,7 @@ impl NavigateToItem {
     &self,
     language_server: &language_server::Inner,
   ) -> Option<lsp::SymbolInformation> {
-    let specifier = normalize_specifier(&self.file_name).ok()?;
+    let specifier = resolve_url(&self.file_name).ok()?;
     let asset_or_doc =
       language_server.get_asset_or_document(&specifier).ok()?;
     let line_index = asset_or_doc.line_index();
@@ -1810,7 +1943,7 @@ pub struct ImplementationLocation {
 }
 
 impl ImplementationLocation {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -1823,7 +1956,7 @@ impl ImplementationLocation {
     line_index: Arc<LineIndex>,
     language_server: &language_server::Inner,
   ) -> lsp::Location {
-    let specifier = normalize_specifier(&self.document_span.file_name)
+    let specifier = resolve_url(&self.document_span.file_name)
       .unwrap_or_else(|_| ModuleSpecifier::parse("deno://invalid").unwrap());
     let uri = language_server
       .url_map
@@ -1857,7 +1990,7 @@ pub struct RenameLocation {
 }
 
 impl RenameLocation {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -1881,7 +2014,7 @@ impl RenameLocations {
       lsp::TextDocumentEdit,
     > = HashMap::new();
     for location in self.locations.iter() {
-      let specifier = normalize_specifier(&location.document_span.file_name)?;
+      let specifier = resolve_url(&location.document_span.file_name)?;
       let uri = language_server.url_map.normalize_specifier(&specifier)?;
       let asset_or_doc = language_server.get_asset_or_document(&specifier)?;
 
@@ -1955,7 +2088,7 @@ pub struct DefinitionInfo {
 }
 
 impl DefinitionInfo {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -1972,7 +2105,7 @@ pub struct DefinitionInfoAndBoundSpan {
 }
 
 impl DefinitionInfoAndBoundSpan {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2068,7 +2201,7 @@ pub struct FileTextChanges {
 }
 
 impl FileTextChanges {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2080,7 +2213,7 @@ impl FileTextChanges {
     &self,
     language_server: &language_server::Inner,
   ) -> Result<lsp::TextDocumentEdit, AnyError> {
-    let specifier = normalize_specifier(&self.file_name)?;
+    let specifier = resolve_url(&self.file_name)?;
     let asset_or_doc = language_server.get_asset_or_document(&specifier)?;
     let edits = self
       .text_changes
@@ -2101,7 +2234,7 @@ impl FileTextChanges {
     language_server: &language_server::Inner,
   ) -> Result<Vec<lsp::DocumentChangeOperation>, AnyError> {
     let mut ops = Vec::<lsp::DocumentChangeOperation>::new();
-    let specifier = normalize_specifier(&self.file_name)?;
+    let specifier = resolve_url(&self.file_name)?;
     let maybe_asset_or_document = if !self.is_new_file.unwrap_or(false) {
       let asset_or_doc = language_server.get_asset_or_document(&specifier)?;
       Some(asset_or_doc)
@@ -2355,7 +2488,7 @@ pub struct RefactorEditInfo {
 }
 
 impl RefactorEditInfo {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2383,7 +2516,7 @@ pub struct CodeAction {
 }
 
 impl CodeAction {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2416,7 +2549,7 @@ pub struct CodeFixAction {
 }
 
 impl CodeFixAction {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2435,7 +2568,7 @@ pub struct CombinedCodeActions {
 }
 
 impl CombinedCodeActions {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2454,7 +2587,7 @@ pub struct ReferencedSymbol {
 }
 
 impl ReferencedSymbol {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2474,7 +2607,7 @@ pub struct ReferencedSymbolDefinitionInfo {
 }
 
 impl ReferencedSymbolDefinitionInfo {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2493,7 +2626,7 @@ pub struct ReferencedSymbolEntry {
 }
 
 impl ReferencedSymbolEntry {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2512,7 +2645,7 @@ pub struct ReferenceEntry {
 }
 
 impl ReferenceEntry {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2527,7 +2660,7 @@ impl ReferenceEntry {
     line_index: Arc<LineIndex>,
     url_map: &LspUrlMap,
   ) -> lsp::Location {
-    let specifier = normalize_specifier(&self.document_span.file_name)
+    let specifier = resolve_url(&self.document_span.file_name)
       .unwrap_or_else(|_| INVALID_SPECIFIER.clone());
     let uri = url_map
       .normalize_specifier(&specifier)
@@ -2554,7 +2687,7 @@ pub struct CallHierarchyItem {
 }
 
 impl CallHierarchyItem {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2567,7 +2700,7 @@ impl CallHierarchyItem {
     language_server: &language_server::Inner,
     maybe_root_path: Option<&Path>,
   ) -> Option<lsp::CallHierarchyItem> {
-    let target_specifier = normalize_specifier(&self.file).ok()?;
+    let target_specifier = resolve_url(&self.file).ok()?;
     let target_asset_or_doc =
       language_server.get_maybe_asset_or_document(&target_specifier)?;
 
@@ -2584,8 +2717,8 @@ impl CallHierarchyItem {
     language_server: &language_server::Inner,
     maybe_root_path: Option<&Path>,
   ) -> lsp::CallHierarchyItem {
-    let target_specifier = normalize_specifier(&self.file)
-      .unwrap_or_else(|_| INVALID_SPECIFIER.clone());
+    let target_specifier =
+      resolve_url(&self.file).unwrap_or_else(|_| INVALID_SPECIFIER.clone());
     let uri = language_server
       .url_map
       .normalize_specifier(&target_specifier)
@@ -2661,7 +2794,7 @@ pub struct CallHierarchyIncomingCall {
 }
 
 impl CallHierarchyIncomingCall {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2674,7 +2807,7 @@ impl CallHierarchyIncomingCall {
     language_server: &language_server::Inner,
     maybe_root_path: Option<&Path>,
   ) -> Option<lsp::CallHierarchyIncomingCall> {
-    let target_specifier = normalize_specifier(&self.from.file).ok()?;
+    let target_specifier = resolve_url(&self.from.file).ok()?;
     let target_asset_or_doc =
       language_server.get_maybe_asset_or_document(&target_specifier)?;
 
@@ -2701,7 +2834,7 @@ pub struct CallHierarchyOutgoingCall {
 }
 
 impl CallHierarchyOutgoingCall {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -2715,7 +2848,7 @@ impl CallHierarchyOutgoingCall {
     language_server: &language_server::Inner,
     maybe_root_path: Option<&Path>,
   ) -> Option<lsp::CallHierarchyOutgoingCall> {
-    let target_specifier = normalize_specifier(&self.to.file).ok()?;
+    let target_specifier = resolve_url(&self.to.file).ok()?;
     let target_asset_or_doc =
       language_server.get_maybe_asset_or_document(&target_specifier)?;
 
@@ -2753,8 +2886,7 @@ fn parse_code_actions(
       let asset_or_doc =
         language_server.get_asset_or_document(&data.specifier)?;
       for change in &ts_action.changes {
-        let change_specifier = normalize_specifier(&change.file_name)?;
-        if data.specifier == change_specifier {
+        if data.specifier.as_str() == change.file_name {
           additional_text_edits.extend(change.text_changes.iter().map(|tc| {
             let mut text_edit = tc.as_text_edit(asset_or_doc.line_index());
             if let Some(specifier_rewrite) = &data.specifier_rewrite {
@@ -2779,9 +2911,7 @@ fn parse_code_actions(
             .changes
             .clone()
             .into_iter()
-            .filter(|ch| {
-              normalize_specifier(&ch.file_name).unwrap() == data.specifier
-            })
+            .filter(|ch| ch.file_name == data.specifier.as_str())
             .collect();
           json!({
             "commands": ca.commands,
@@ -2855,16 +2985,19 @@ fn get_parameters_from_parts(parts: &[SymbolDisplayPart]) -> Vec<String> {
 pub struct CompletionEntryDetails {
   display_parts: Vec<SymbolDisplayPart>,
   documentation: Option<Vec<SymbolDisplayPart>>,
+  #[serde(skip_serializing_if = "Option::is_none")]
   tags: Option<Vec<JsDocTagInfo>>,
   name: String,
   kind: ScriptElementKind,
   kind_modifiers: String,
+  #[serde(skip_serializing_if = "Option::is_none")]
   code_actions: Option<Vec<CodeAction>>,
+  #[serde(skip_serializing_if = "Option::is_none")]
   source_display: Option<Vec<SymbolDisplayPart>>,
 }
 
 impl CompletionEntryDetails {
-  pub fn normalize(
+  fn normalize(
     &mut self,
     specifier_map: &TscSpecifierMap,
   ) -> Result<(), AnyError> {
@@ -3211,9 +3344,7 @@ impl CompletionEntry {
         if let Ok(import_data) =
           serde_json::from_value::<CompletionEntryDataImport>(data.clone())
         {
-          if let Ok(import_specifier) =
-            normalize_specifier(import_data.file_name)
-          {
+          if let Ok(import_specifier) = resolve_url(&import_data.file_name) {
             if let Some(new_module_specifier) = language_server
               .get_ts_response_import_mapper()
               .check_specifier(&import_specifier, specifier)
@@ -3521,6 +3652,10 @@ pub struct TscSpecifierMap {
 }
 
 impl TscSpecifierMap {
+  pub fn new() -> Self {
+    Self::default()
+  }
+
   /// Convert the specifier to one compatible with tsc. Cache the resulting
   /// mapping in case it needs to be reversed.
   // TODO(nayeemrmn): Factor in out-of-band media type here.
@@ -3632,13 +3767,6 @@ impl State {
   }
 }
 
-fn normalize_specifier<S: AsRef<str>>(
-  specifier: S,
-) -> Result<ModuleSpecifier, AnyError> {
-  resolve_url(specifier.as_ref().replace(".d.ts.d.ts", ".d.ts").as_str())
-    .map_err(|err| err.into())
-}
-
 #[derive(Debug, Deserialize, Serialize)]
 #[serde(rename_all = "camelCase")]
 struct SpecifierArgs {
@@ -4214,404 +4342,20 @@ pub struct GetNavigateToItemsArgs {
   pub file: Option<String>,
 }
 
-/// Methods that are supported by the Language Service in the compiler isolate.
-#[derive(Debug)]
-enum RequestMethod {
-  /// Configure the compilation settings for the server.
-  Configure(TsConfig),
-  /// Get rename locations at a given position.
-  FindRenameLocations {
-    specifier: ModuleSpecifier,
-    position: u32,
-    find_in_strings: bool,
-    find_in_comments: bool,
-    provide_prefix_and_suffix_text_for_rename: bool,
-  },
-  GetAssets,
-  /// Retrieve the possible refactor info for a range of a file.
-  GetApplicableRefactors(
-    (ModuleSpecifier, TextSpan, Option<UserPreferences>, String),
-  ),
-  /// Retrieve the refactor edit info for a range.
-  GetEditsForRefactor(
-    (
-      ModuleSpecifier,
-      FormatCodeSettings,
-      TextSpan,
-      String,
-      String,
-      Option<UserPreferences>,
-    ),
-  ),
-  /// Retrieve the refactor edit info for a range.
-  GetEditsForFileRename(
-    (
-      ModuleSpecifier,
-      ModuleSpecifier,
-      FormatCodeSettings,
-      UserPreferences,
-    ),
-  ),
-  /// Retrieve code fixes for a range of a file with the provided error codes.
-  GetCodeFixes(
-    (
-      ModuleSpecifier,
-      u32,
-      u32,
-      Vec<String>,
-      FormatCodeSettings,
-      UserPreferences,
-    ),
-  ),
-  /// Get completion information at a given position (IntelliSense).
-  GetCompletions(
-    (
-      ModuleSpecifier,
-      u32,
-      GetCompletionsAtPositionOptions,
-      FormatCodeSettings,
-    ),
-  ),
-  /// Get details about a specific completion entry.
-  GetCompletionDetails(GetCompletionDetailsArgs),
-  /// Retrieve the combined code fixes for a fix id for a module.
-  GetCombinedCodeFix(
-    (ModuleSpecifier, Value, FormatCodeSettings, UserPreferences),
-  ),
-  /// Get declaration information for a specific position.
-  GetDefinition((ModuleSpecifier, u32)),
-  /// Return diagnostics for given file.
-  GetDiagnostics(Vec<ModuleSpecifier>),
-  /// Return document highlights at position.
-  GetDocumentHighlights((ModuleSpecifier, u32, Vec<ModuleSpecifier>)),
-  /// Get semantic highlights information for a particular file.
-  GetEncodedSemanticClassifications((ModuleSpecifier, TextSpan)),
-  /// Get implementation information for a specific position.
-  GetImplementation((ModuleSpecifier, u32)),
-  /// Get "navigate to" items, which are converted to workspace symbols
-  GetNavigateToItems(GetNavigateToItemsArgs),
-  /// Get a "navigation tree" for a specifier.
-  GetNavigationTree(ModuleSpecifier),
-  /// Get outlining spans for a specifier.
-  GetOutliningSpans(ModuleSpecifier),
-  /// Return quick info at position (hover information).
-  GetQuickInfo((ModuleSpecifier, u32)),
-  /// Finds the document references for a specific position.
-  FindReferences {
-    specifier: ModuleSpecifier,
-    position: u32,
-  },
-  /// Get signature help items for a specific position.
-  GetSignatureHelpItems((ModuleSpecifier, u32, SignatureHelpItemsOptions)),
-  /// Get a selection range for a specific position.
-  GetSmartSelectionRange((ModuleSpecifier, u32)),
-  /// Get the diagnostic codes that support some form of code fix.
-  GetSupportedCodeFixes,
-  /// Get the type definition information for a specific position.
-  GetTypeDefinition {
-    specifier: ModuleSpecifier,
-    position: u32,
-  },
-  /// Resolve a call hierarchy item for a specific position.
-  PrepareCallHierarchy((ModuleSpecifier, u32)),
-  /// Resolve incoming call hierarchy items for a specific position.
-  ProvideCallHierarchyIncomingCalls((ModuleSpecifier, u32)),
-  /// Resolve outgoing call hierarchy items for a specific position.
-  ProvideCallHierarchyOutgoingCalls((ModuleSpecifier, u32)),
-  /// Resolve inlay hints for a specific text span
-  ProvideInlayHints((ModuleSpecifier, TextSpan, UserPreferences)),
-
-  // Special request, used only internally by the LSP
-  Restart,
-}
-
-impl RequestMethod {
-  fn to_value(&self, state: &mut State, id: usize) -> Value {
-    match self {
-      RequestMethod::Configure(config) => json!({
-        "id": id,
-        "method": "configure",
-        "compilerOptions": config,
-      }),
-      RequestMethod::FindRenameLocations {
-        specifier,
-        position,
-        find_in_strings,
-        find_in_comments,
-        provide_prefix_and_suffix_text_for_rename,
-      } => {
-        json!({
-          "id": id,
-          "method": "findRenameLocations",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "position": position,
-          "findInStrings": find_in_strings,
-          "findInComments": find_in_comments,
-          "providePrefixAndSuffixTextForRename": provide_prefix_and_suffix_text_for_rename
-        })
-      }
-      RequestMethod::GetAssets => json!({
-        "id": id,
-        "method": "getAssets",
-      }),
-      RequestMethod::GetApplicableRefactors((
-        specifier,
-        span,
-        preferences,
-        kind,
-      )) => json!({
-        "id": id,
-        "method": "getApplicableRefactors",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "range": { "pos": span.start, "end": span.start + span.length },
-        "preferences": preferences,
-        "kind": kind,
-      }),
-      RequestMethod::GetEditsForRefactor((
-        specifier,
-        format_code_settings,
-        span,
-        refactor_name,
-        action_name,
-        preferences,
-      )) => json!({
-        "id": id,
-        "method": "getEditsForRefactor",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "formatCodeSettings": format_code_settings,
-        "range": { "pos": span.start, "end": span.start + span.length},
-        "refactorName": refactor_name,
-        "actionName": action_name,
-        "preferences": preferences,
-      }),
-      RequestMethod::GetEditsForFileRename((
-        old_specifier,
-        new_specifier,
-        format_code_settings,
-        preferences,
-      )) => json!({
-        "id": id,
-        "method": "getEditsForFileRename",
-        "oldSpecifier": state.specifier_map.denormalize(old_specifier),
-        "newSpecifier": state.specifier_map.denormalize(new_specifier),
-        "formatCodeSettings": format_code_settings,
-        "preferences": preferences,
-      }),
-      RequestMethod::GetCodeFixes((
-        specifier,
-        start_pos,
-        end_pos,
-        error_codes,
-        format_code_settings,
-        preferences,
-      )) => json!({
-        "id": id,
-        "method": "getCodeFixes",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "startPosition": start_pos,
-        "endPosition": end_pos,
-        "errorCodes": error_codes,
-        "formatCodeSettings": format_code_settings,
-        "preferences": preferences,
-      }),
-      RequestMethod::GetCombinedCodeFix((
-        specifier,
-        fix_id,
-        format_code_settings,
-        preferences,
-      )) => json!({
-        "id": id,
-        "method": "getCombinedCodeFix",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "fixId": fix_id,
-        "formatCodeSettings": format_code_settings,
-        "preferences": preferences,
-      }),
-      RequestMethod::GetCompletionDetails(args) => {
-        let mut args = json!(args);
-        let specifier =
-          args.as_object_mut().unwrap().get_mut("specifier").unwrap();
-        if let Ok(s) = ModuleSpecifier::parse(specifier.as_str().unwrap()) {
-          *specifier = json!(state.specifier_map.denormalize(&s));
-        }
-        json!({
-          "id": id,
-          "method": "getCompletionDetails",
-          "args": args
-        })
-      }
-      RequestMethod::GetCompletions((
-        specifier,
-        position,
-        preferences,
-        format_code_settings,
-      )) => {
-        json!({
-          "id": id,
-          "method": "getCompletions",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "position": position,
-          "preferences": preferences,
-          "formatCodeSettings": format_code_settings,
-        })
-      }
-      RequestMethod::GetDefinition((specifier, position)) => json!({
-        "id": id,
-        "method": "getDefinition",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "position": position,
-      }),
-      RequestMethod::GetDiagnostics(specifiers) => json!({
-        "id": id,
-        "method": "getDiagnostics",
-        "specifiers": specifiers.iter().map(|s| state.specifier_map.denormalize(s)).collect::<Vec<String>>(),
-      }),
-      RequestMethod::GetDocumentHighlights((
-        specifier,
-        position,
-        files_to_search,
-      )) => json!({
-        "id": id,
-        "method": "getDocumentHighlights",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "position": position,
-        "filesToSearch": files_to_search.iter().map(|s| state.specifier_map.denormalize(s)).collect::<Vec<_>>(),
-      }),
-      RequestMethod::GetEncodedSemanticClassifications((specifier, span)) => {
-        json!({
-          "id": id,
-          "method": "getEncodedSemanticClassifications",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "span": span,
-        })
-      }
-      RequestMethod::GetImplementation((specifier, position)) => json!({
-        "id": id,
-        "method": "getImplementation",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "position": position,
-      }),
-      RequestMethod::GetNavigateToItems(GetNavigateToItemsArgs {
-        search,
-        max_result_count,
-        file,
-      }) => json!({
-        "id": id,
-        "method": "getNavigateToItems",
-        "search": search,
-        "maxResultCount": max_result_count,
-        "file": file,
-      }),
-      RequestMethod::GetNavigationTree(specifier) => json!({
-        "id": id,
-        "method": "getNavigationTree",
-        "specifier": state.specifier_map.denormalize(specifier),
-      }),
-      RequestMethod::GetOutliningSpans(specifier) => json!({
-        "id": id,
-        "method": "getOutliningSpans",
-        "specifier": state.specifier_map.denormalize(specifier),
-      }),
-      RequestMethod::GetQuickInfo((specifier, position)) => json!({
-        "id": id,
-        "method": "getQuickInfo",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "position": position,
-      }),
-      RequestMethod::FindReferences {
-        specifier,
-        position,
-      } => json!({
-        "id": id,
-        "method": "findReferences",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "position": position,
-      }),
-      RequestMethod::GetSignatureHelpItems((specifier, position, options)) => {
-        json!({
-          "id": id,
-          "method": "getSignatureHelpItems",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "position": position,
-          "options": options,
-        })
-      }
-      RequestMethod::GetSmartSelectionRange((specifier, position)) => {
-        json!({
-          "id": id,
-          "method": "getSmartSelectionRange",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "position": position
-        })
-      }
-      RequestMethod::GetSupportedCodeFixes => json!({
-        "id": id,
-        "method": "getSupportedCodeFixes",
-      }),
-      RequestMethod::GetTypeDefinition {
-        specifier,
-        position,
-      } => json!({
-        "id": id,
-        "method": "getTypeDefinition",
-        "specifier": state.specifier_map.denormalize(specifier),
-        "position": position
-      }),
-      RequestMethod::PrepareCallHierarchy((specifier, position)) => {
-        json!({
-          "id": id,
-          "method": "prepareCallHierarchy",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "position": position
-        })
-      }
-      RequestMethod::ProvideCallHierarchyIncomingCalls((
-        specifier,
-        position,
-      )) => {
-        json!({
-          "id": id,
-          "method": "provideCallHierarchyIncomingCalls",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "position": position
-        })
-      }
-      RequestMethod::ProvideCallHierarchyOutgoingCalls((
-        specifier,
-        position,
-      )) => {
-        json!({
-          "id": id,
-          "method": "provideCallHierarchyOutgoingCalls",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "position": position
-        })
-      }
-      RequestMethod::ProvideInlayHints((specifier, span, preferences)) => {
-        json!({
-          "id": id,
-          "method": "provideInlayHints",
-          "specifier": state.specifier_map.denormalize(specifier),
-          "span": span,
-          "preferences": preferences,
-        })
-      }
-      RequestMethod::Restart => json!({
-        "id": id,
-        "method": "restart",
-      }),
-    }
-  }
+#[derive(Clone, Debug)]
+struct TscRequest {
+  method: &'static str,
+  args: Value,
 }
 
 /// Send a request into a runtime and return the JSON value of the response.
 fn request(
   runtime: &mut JsRuntime,
   state_snapshot: Arc<StateSnapshot>,
-  method: RequestMethod,
+  request: TscRequest,
   token: CancellationToken,
 ) -> Result<Value, AnyError> {
-  let (performance, request_params) = {
+  let (performance, id) = {
     let op_state = runtime.op_state();
     let mut op_state = op_state.borrow_mut();
     let state = op_state.borrow_mut::<State>();
@@ -4619,10 +4363,18 @@ fn request(
     state.token = token;
     state.last_id += 1;
     let id = state.last_id;
-    (state.performance.clone(), method.to_value(state, id))
+    (state.performance.clone(), id)
   };
-  let mark = performance.mark("request", Some(request_params.clone()));
-  let request_src = format!("globalThis.serverRequest({request_params});");
+  let mark =
+    performance.mark("request", Some((request.method, request.args.clone())));
+  assert!(
+    request.args.is_array(),
+    "Internal error: expected args to be array"
+  );
+  let request_src = format!(
+    "globalThis.serverRequest({id}, \"{}\", {});",
+    request.method, &request.args
+  );
   runtime.execute_script(located_script_name!(), request_src.into())?;
 
   let op_state = runtime.op_state();
@@ -4653,10 +4405,8 @@ mod tests {
   use crate::lsp::documents::Documents;
   use crate::lsp::documents::LanguageId;
   use crate::lsp::text::LineIndex;
-  use crate::tsc::AssetText;
   use pretty_assertions::assert_eq;
   use std::path::Path;
-  use std::path::PathBuf;
   use test_util::TempDir;
 
   fn mock_state_snapshot(
@@ -4688,30 +4438,23 @@ mod tests {
     }
   }
 
-  fn setup(
+  async fn setup(
     temp_dir: &TempDir,
-    debug: bool,
     config: Value,
     sources: &[(&str, &str, i32, LanguageId)],
-  ) -> (JsRuntime, Arc<StateSnapshot>, PathBuf) {
+  ) -> (TsServer, Arc<StateSnapshot>, Arc<GlobalHttpCache>) {
     let location = temp_dir.path().join("deps").to_path_buf();
     let cache =
       Arc::new(GlobalHttpCache::new(location.clone(), RealDenoCacheEnv));
-    let state_snapshot = Arc::new(mock_state_snapshot(sources, &location));
-    let mut runtime = js_runtime(Default::default(), cache, Default::default());
-    start(&mut runtime, debug).unwrap();
+    let snapshot = Arc::new(mock_state_snapshot(sources, &location));
+    let performance = Arc::new(Performance::default());
+    let ts_server = TsServer::new(performance, cache.clone());
     let ts_config = TsConfig::new(config);
-    assert_eq!(
-      request(
-        &mut runtime,
-        state_snapshot.clone(),
-        RequestMethod::Configure(ts_config),
-        Default::default(),
-      )
-      .expect("failed request"),
-      json!(true)
-    );
-    (runtime, state_snapshot, location)
+    assert!(ts_server
+      .configure(snapshot.clone(), ts_config,)
+      .await
+      .unwrap());
+    (ts_server, snapshot, cache)
   }
 
   #[test]
@@ -4729,57 +4472,48 @@ mod tests {
     assert_eq!(actual, r"test [`a link`](http://deno.land/x/mod.ts) test");
   }
 
-  #[test]
-  fn test_project_configure() {
+  #[tokio::test]
+  async fn test_project_configure() {
     let temp_dir = TempDir::new();
     setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
         "noEmit": true,
       }),
       &[],
-    );
+    )
+    .await;
   }
 
-  #[test]
-  fn test_project_reconfigure() {
+  #[tokio::test]
+  async fn test_project_reconfigure() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
         "noEmit": true,
       }),
       &[],
-    );
+    )
+    .await;
     let ts_config = TsConfig::new(json!({
       "target": "esnext",
       "module": "esnext",
       "noEmit": true,
       "lib": ["deno.ns", "deno.worker"]
     }));
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::Configure(ts_config),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
-    assert_eq!(response, json!(true));
+    assert!(ts_server.configure(snapshot, ts_config).await.unwrap());
   }
 
-  #[test]
-  fn test_get_diagnostics() {
+  #[tokio::test]
+  async fn test_get_diagnostics() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -4791,18 +4525,15 @@ mod tests {
         1,
         LanguageId::TypeScript,
       )],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot, vec![specifier], Default::default())
+      .await
+      .unwrap();
     assert_eq!(
-      response,
+      json!(diagnostics),
       json!({
         "file:///a.ts": [
           {
@@ -4825,12 +4556,11 @@ mod tests {
     );
   }
 
-  #[test]
-  fn test_get_diagnostics_lib() {
+  #[tokio::test]
+  async fn test_get_diagnostics_lib() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -4844,25 +4574,21 @@ mod tests {
         1,
         LanguageId::TypeScript,
       )],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
-    assert_eq!(response, json!({ "file:///a.ts": [] }));
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot, vec![specifier], Default::default())
+      .await
+      .unwrap();
+    assert_eq!(json!(diagnostics), json!({ "file:///a.ts": [] }));
   }
 
-  #[test]
-  fn test_module_resolution() {
+  #[tokio::test]
+  async fn test_module_resolution() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -4881,25 +4607,21 @@ mod tests {
         1,
         LanguageId::TypeScript,
       )],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
-    assert_eq!(response, json!({ "file:///a.ts": [] }));
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot, vec![specifier], Default::default())
+      .await
+      .unwrap();
+    assert_eq!(json!(diagnostics), json!({ "file:///a.ts": [] }));
   }
 
-  #[test]
-  fn test_bad_module_specifiers() {
+  #[tokio::test]
+  async fn test_bad_module_specifiers() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -4914,18 +4636,15 @@ mod tests {
         1,
         LanguageId::TypeScript,
       )],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot, vec![specifier], Default::default())
+      .await
+      .unwrap();
     assert_eq!(
-      response,
+      json!(diagnostics),
       json!({
         "file:///a.ts": [{
           "start": {
@@ -4941,18 +4660,16 @@ mod tests {
           "sourceLine": "        import { A } from \".\";",
           "category": 2,
           "code": 6133,
-          "reportsUnnecessary": true,
         }]
       })
     );
   }
 
-  #[test]
-  fn test_remote_modules() {
+  #[tokio::test]
+  async fn test_remote_modules() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -4971,25 +4688,21 @@ mod tests {
         1,
         LanguageId::TypeScript,
       )],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
-    assert_eq!(response, json!({ "file:///a.ts": [] }));
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot, vec![specifier], Default::default())
+      .await
+      .unwrap();
+    assert_eq!(json!(diagnostics), json!({ "file:///a.ts": [] }));
   }
 
-  #[test]
-  fn test_partial_modules() {
+  #[tokio::test]
+  async fn test_partial_modules() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -5011,18 +4724,15 @@ mod tests {
         1,
         LanguageId::TypeScript,
       )],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot, vec![specifier], Default::default())
+      .await
+      .unwrap();
     assert_eq!(
-      response,
+      json!(diagnostics),
       json!({
         "file:///a.ts": [{
           "start": {
@@ -5038,7 +4748,6 @@ mod tests {
           "sourceLine": "        import {",
           "category": 2,
           "code": 6192,
-          "reportsUnnecessary": true
         }, {
           "start": {
             "line": 8,
@@ -5058,12 +4767,11 @@ mod tests {
     );
   }
 
-  #[test]
-  fn test_no_debug_failure() {
+  #[tokio::test]
+  async fn test_no_debug_failure() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -5076,18 +4784,15 @@ mod tests {
         1,
         LanguageId::TypeScript,
       )],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot, vec![specifier], Default::default())
+      .await
+      .unwrap();
     assert_eq!(
-      response,
+      json!(diagnostics),
       json!({
         "file:///a.ts": [
           {
@@ -5110,23 +4815,16 @@ mod tests {
     );
   }
 
-  #[test]
-  fn test_request_assets() {
+  #[tokio::test]
+  async fn test_request_assets() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) =
-      setup(&temp_dir, false, json!({}), &[]);
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetAssets,
-      Default::default(),
-    )
-    .unwrap();
-    let assets: Vec<AssetText> = serde_json::from_value(result).unwrap();
+    let (ts_server, snapshot, _) = setup(&temp_dir, json!({}), &[]).await;
+    let assets = get_isolate_assets(&ts_server, snapshot).await;
     let mut asset_names = assets
       .iter()
       .map(|a| {
-        a.specifier
+        a.specifier()
+          .to_string()
           .replace("asset:///lib.", "")
           .replace(".d.ts", "")
       })
@@ -5135,29 +4833,25 @@ mod tests {
       include_str!(concat!(env!("OUT_DIR"), "/lib_file_names.json")),
     )
     .unwrap();
-
     asset_names.sort();
-    expected_asset_names.sort();
 
-    // You might have found this assertion starts failing after upgrading TypeScript.
-    // Ensure build.rs is updated so these match.
+    expected_asset_names.sort();
     assert_eq!(asset_names, expected_asset_names);
 
     // get some notification when the size of the assets grows
     let mut total_size = 0;
     for asset in assets {
-      total_size += asset.text.len();
+      total_size += asset.text().len();
     }
     assert!(total_size > 0);
     assert!(total_size < 2_000_000); // currently as of TS 4.6, it's 0.7MB
   }
 
-  #[test]
-  fn test_modify_sources() {
+  #[tokio::test]
+  async fn test_modify_sources() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, location) = setup(
+    let (ts_server, snapshot, cache) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -5175,8 +4869,8 @@ mod tests {
         1,
         LanguageId::TypeScript,
       )],
-    );
-    let cache = Arc::new(GlobalHttpCache::new(location, RealDenoCacheEnv));
+    )
+    .await;
     let specifier_dep =
       resolve_url("https://deno.land/x/example/a.ts").unwrap();
     cache
@@ -5187,16 +4881,12 @@ mod tests {
       )
       .unwrap();
     let specifier = resolve_url("file:///a.ts").unwrap();
-    let result = request(
-      &mut runtime,
-      state_snapshot.clone(),
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot.clone(), vec![specifier], Default::default())
+      .await
+      .unwrap();
     assert_eq!(
-      response,
+      json!(diagnostics),
       json!({
         "file:///a.ts": [
           {
@@ -5225,16 +4915,12 @@ mod tests {
       )
       .unwrap();
     let specifier = resolve_url("file:///a.ts").unwrap();
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetDiagnostics(vec![specifier]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
+    let diagnostics = ts_server
+      .get_diagnostics(snapshot.clone(), vec![specifier], Default::default())
+      .await
+      .unwrap();
     assert_eq!(
-      response,
+      json!(diagnostics),
       json!({
         "file:///a.ts": []
       })
@@ -5270,8 +4956,8 @@ mod tests {
     assert_eq!(actual, Some("abc".to_string()));
   }
 
-  #[test]
-  fn test_completions() {
+  #[tokio::test]
+  async fn test_completions() {
     let fixture = r#"
       import { B } from "https://deno.land/x/b/mod.ts";
 
@@ -5287,9 +4973,8 @@ mod tests {
       })
       .unwrap();
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -5297,19 +4982,12 @@ mod tests {
         "noEmit": true,
       }),
       &[("file:///a.ts", fixture, 1, LanguageId::TypeScript)],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot.clone(),
-      RequestMethod::GetDiagnostics(vec![specifier.clone()]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let result = request(
-      &mut runtime,
-      state_snapshot.clone(),
-      RequestMethod::GetCompletions((
+    let info = ts_server
+      .get_completions(
+        snapshot.clone(),
         specifier.clone(),
         position,
         GetCompletionsAtPositionOptions {
@@ -5321,31 +4999,28 @@ mod tests {
           trigger_kind: None,
         },
         Default::default(),
-      )),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response: CompletionInfo =
-      serde_json::from_value(result.unwrap()).unwrap();
-    assert_eq!(response.entries.len(), 22);
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetCompletionDetails(GetCompletionDetailsArgs {
-        specifier,
-        position,
-        name: "log".to_string(),
-        source: None,
-        preferences: None,
-        format_code_settings: None,
-        data: None,
-      }),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let response = result.unwrap();
+      )
+      .await
+      .unwrap();
+    assert_eq!(info.entries.len(), 22);
+    let details = ts_server
+      .get_completion_details(
+        snapshot.clone(),
+        GetCompletionDetailsArgs {
+          specifier,
+          position,
+          name: "log".to_string(),
+          format_code_settings: None,
+          source: None,
+          preferences: None,
+          data: None,
+        },
+      )
+      .await
+      .unwrap()
+      .unwrap();
     assert_eq!(
-      response,
+      json!(details),
       json!({
         "name": "log",
         "kindModifiers": "declare",
@@ -5433,8 +5108,8 @@ mod tests {
     );
   }
 
-  #[test]
-  fn test_completions_fmt() {
+  #[tokio::test]
+  async fn test_completions_fmt() {
     let fixture_a = r#"
       console.log(someLongVaria)
     "#;
@@ -5449,9 +5124,8 @@ mod tests {
       })
       .unwrap();
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -5462,24 +5136,17 @@ mod tests {
         ("file:///a.ts", fixture_a, 1, LanguageId::TypeScript),
         ("file:///b.ts", fixture_b, 1, LanguageId::TypeScript),
       ],
-    );
+    )
+    .await;
     let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot.clone(),
-      RequestMethod::GetDiagnostics(vec![specifier.clone()]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
     let fmt_options_config = FmtOptionsConfig {
       semi_colons: Some(false),
       single_quote: Some(true),
       ..Default::default()
     };
-    let result = request(
-      &mut runtime,
-      state_snapshot.clone(),
-      RequestMethod::GetCompletions((
+    let info = ts_server
+      .get_completions(
+        snapshot.clone(),
         specifier.clone(),
         position,
         GetCompletionsAtPositionOptions {
@@ -5491,37 +5158,36 @@ mod tests {
           },
           ..Default::default()
         },
-        (&fmt_options_config).into(),
-      )),
-      Default::default(),
-    )
-    .unwrap();
-    let info: CompletionInfo = serde_json::from_value(result).unwrap();
+        FormatCodeSettings::from(&fmt_options_config),
+      )
+      .await
+      .unwrap();
     let entry = info
       .entries
       .iter()
       .find(|e| &e.name == "someLongVariable")
       .unwrap();
-    let result = request(
-      &mut runtime,
-      state_snapshot,
-      RequestMethod::GetCompletionDetails(GetCompletionDetailsArgs {
-        specifier,
-        position,
-        name: entry.name.clone(),
-        source: entry.source.clone(),
-        preferences: Some(UserPreferences {
-          quote_preference: Some((&fmt_options_config).into()),
-          ..Default::default()
-        }),
-        format_code_settings: Some((&fmt_options_config).into()),
-        data: entry.data.clone(),
-      }),
-      Default::default(),
-    )
-    .unwrap();
-    let details: CompletionEntryDetails =
-      serde_json::from_value(result).unwrap();
+    let details = ts_server
+      .get_completion_details(
+        snapshot.clone(),
+        GetCompletionDetailsArgs {
+          specifier,
+          position,
+          name: entry.name.clone(),
+          format_code_settings: Some(FormatCodeSettings::from(
+            &fmt_options_config,
+          )),
+          source: entry.source.clone(),
+          preferences: Some(UserPreferences {
+            quote_preference: Some((&fmt_options_config).into()),
+            ..Default::default()
+          }),
+          data: entry.data.clone(),
+        },
+      )
+      .await
+      .unwrap()
+      .unwrap();
     let actions = details.code_actions.unwrap();
     let action = actions
       .iter()
@@ -5535,12 +5201,11 @@ mod tests {
     );
   }
 
-  #[test]
-  fn test_get_edits_for_file_rename() {
+  #[tokio::test]
+  async fn test_get_edits_for_file_rename() {
     let temp_dir = TempDir::new();
-    let (mut runtime, state_snapshot, _) = setup(
+    let (ts_server, snapshot, _) = setup(
       &temp_dir,
-      false,
       json!({
         "target": "esnext",
         "module": "esnext",
@@ -5556,29 +5221,18 @@ mod tests {
         ),
         ("file:///b.ts", r#""#, 1, LanguageId::TypeScript),
       ],
-    );
-    let specifier = resolve_url("file:///a.ts").expect("could not resolve url");
-    let result = request(
-      &mut runtime,
-      state_snapshot.clone(),
-      RequestMethod::GetDiagnostics(vec![specifier.clone()]),
-      Default::default(),
-    );
-    assert!(result.is_ok());
-    let changes = request(
-      &mut runtime,
-      state_snapshot.clone(),
-      RequestMethod::GetEditsForFileRename((
+    )
+    .await;
+    let changes = ts_server
+      .get_edits_for_file_rename(
+        snapshot,
         resolve_url("file:///b.ts").unwrap(),
         resolve_url("file:///c.ts").unwrap(),
-        Default::default(),
-        Default::default(),
-      )),
-      Default::default(),
-    )
-    .unwrap();
-    let changes: Vec<FileTextChanges> =
-      serde_json::from_value(changes).unwrap();
+        FormatCodeSettings::default(),
+        UserPreferences::default(),
+      )
+      .await
+      .unwrap();
     assert_eq!(
       changes,
       vec![FileTextChanges {
diff --git a/cli/tsc/99_main_compiler.js b/cli/tsc/99_main_compiler.js
index 8978bf1bef..e246d5d0c3 100644
--- a/cli/tsc/99_main_compiler.js
+++ b/cli/tsc/99_main_compiler.js
@@ -968,26 +968,23 @@ delete Object.prototype.__proto__;
     ops.op_respond({ id, data });
   }
 
-  /**
-   * @param {LanguageServerRequest} request
-   */
-  function serverRequest({ id, ...request }) {
+  function serverRequest(id, method, args) {
     if (logDebug) {
-      debug(`serverRequest()`, { id, ...request });
+      debug(`serverRequest()`, id, method, args);
     }
 
     // reset all memoized source files names
     scriptFileNamesCache = undefined;
     // evict all memoized source file versions
     scriptVersionCache.clear();
-    switch (request.method) {
-      case "restart": {
+    switch (method) {
+      case "$restart": {
         serverRestart();
         return respond(id, true);
       }
-      case "configure": {
+      case "$configure": {
         const { options, errors } = ts
-          .convertCompilerOptionsFromJson(request.compilerOptions, "");
+          .convertCompilerOptionsFromJson(args[0], "");
         Object.assign(options, {
           allowNonTsExtensions: true,
           allowImportingTsExtensions: true,
@@ -998,141 +995,20 @@ delete Object.prototype.__proto__;
         compilationSettings = options;
         return respond(id, true);
       }
-      case "findRenameLocations": {
+      case "$getSupportedCodeFixes": {
         return respond(
           id,
-          languageService.findRenameLocations(
-            request.specifier,
-            request.position,
-            request.findInStrings,
-            request.findInComments,
-            request.providePrefixAndSuffixTextForRename,
-          ),
+          ts.getSupportedCodeFixes(),
         );
       }
-      case "getAssets": {
+      case "$getAssets": {
         return respond(id, getAssets());
       }
-      case "getApplicableRefactors": {
-        return respond(
-          id,
-          languageService.getApplicableRefactors(
-            request.specifier,
-            request.range,
-            {
-              ...(request.preferences ?? {}),
-              allowTextChangesInNewFiles: true,
-              provideRefactorNotApplicableReason: true,
-            },
-            undefined,
-            request.kind,
-          ),
-        );
-      }
-      case "getEditsForRefactor": {
-        return respond(
-          id,
-          languageService.getEditsForRefactor(
-            request.specifier,
-            {
-              ...request.formatCodeSettings,
-              indentStyle: ts.IndentStyle.Smart,
-              insertSpaceBeforeAndAfterBinaryOperators: true,
-              insertSpaceAfterCommaDelimiter: true,
-            },
-            request.range,
-            request.refactorName,
-            request.actionName,
-            request.preferences,
-          ),
-        );
-      }
-      case "getEditsForFileRename": {
-        return respond(
-          id,
-          languageService.getEditsForFileRename(
-            request.oldSpecifier,
-            request.newSpecifier,
-            request.formatCodeSettings,
-            request.preferences,
-          ),
-        );
-      }
-      case "getCodeFixes": {
-        return respond(
-          id,
-          languageService.getCodeFixesAtPosition(
-            request.specifier,
-            request.startPosition,
-            request.endPosition,
-            request.errorCodes.map((v) => Number(v)),
-            {
-              ...request.formatCodeSettings,
-              indentStyle: ts.IndentStyle.Block,
-            },
-            request.preferences,
-          ),
-        );
-      }
-      case "getCombinedCodeFix": {
-        return respond(
-          id,
-          languageService.getCombinedCodeFix(
-            {
-              type: "file",
-              fileName: request.specifier,
-            },
-            request.fixId,
-            {
-              ...request.formatCodeSettings,
-              indentStyle: ts.IndentStyle.Block,
-            },
-            request.preferences,
-          ),
-        );
-      }
-      case "getCompletionDetails": {
-        if (logDebug) {
-          debug("request", request);
-        }
-        return respond(
-          id,
-          languageService.getCompletionEntryDetails(
-            request.args.specifier,
-            request.args.position,
-            request.args.name,
-            request.args.formatCodeSettings ?? {},
-            request.args.source,
-            request.args.preferences,
-            request.args.data,
-          ),
-        );
-      }
-      case "getCompletions": {
-        return respond(
-          id,
-          languageService.getCompletionsAtPosition(
-            request.specifier,
-            request.position,
-            request.preferences,
-            request.formatCodeSettings,
-          ),
-        );
-      }
-      case "getDefinition": {
-        return respond(
-          id,
-          languageService.getDefinitionAndBoundSpan(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "getDiagnostics": {
+      case "$getDiagnostics": {
         try {
           /** @type {Record<string, any[]>} */
           const diagnosticMap = {};
-          for (const specifier of request.specifiers) {
+          for (const specifier of args[0]) {
             diagnosticMap[specifier] = fromTypeScriptDiagnostics([
               ...languageService.getSemanticDiagnostics(specifier),
               ...languageService.getSuggestionDiagnostics(specifier),
@@ -1154,151 +1030,18 @@ delete Object.prototype.__proto__;
           return respond(id, {});
         }
       }
-      case "getDocumentHighlights": {
-        return respond(
-          id,
-          languageService.getDocumentHighlights(
-            request.specifier,
-            request.position,
-            request.filesToSearch,
-          ),
-        );
-      }
-      case "getEncodedSemanticClassifications": {
-        return respond(
-          id,
-          languageService.getEncodedSemanticClassifications(
-            request.specifier,
-            request.span,
-            ts.SemanticClassificationFormat.TwentyTwenty,
-          ),
-        );
-      }
-      case "getImplementation": {
-        return respond(
-          id,
-          languageService.getImplementationAtPosition(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "getNavigateToItems": {
-        return respond(
-          id,
-          languageService.getNavigateToItems(
-            request.search,
-            request.maxResultCount,
-            request.fileName,
-          ),
-        );
-      }
-      case "getNavigationTree": {
-        return respond(
-          id,
-          languageService.getNavigationTree(request.specifier),
-        );
-      }
-      case "getOutliningSpans": {
-        return respond(
-          id,
-          languageService.getOutliningSpans(
-            request.specifier,
-          ),
-        );
-      }
-      case "getQuickInfo": {
-        return respond(
-          id,
-          languageService.getQuickInfoAtPosition(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "findReferences": {
-        return respond(
-          id,
-          languageService.findReferences(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "getSignatureHelpItems": {
-        return respond(
-          id,
-          languageService.getSignatureHelpItems(
-            request.specifier,
-            request.position,
-            request.options,
-          ),
-        );
-      }
-      case "getSmartSelectionRange": {
-        return respond(
-          id,
-          languageService.getSmartSelectionRange(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "getSupportedCodeFixes": {
-        return respond(
-          id,
-          ts.getSupportedCodeFixes(),
-        );
-      }
-      case "getTypeDefinition": {
-        return respond(
-          id,
-          languageService.getTypeDefinitionAtPosition(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "prepareCallHierarchy": {
-        return respond(
-          id,
-          languageService.prepareCallHierarchy(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "provideCallHierarchyIncomingCalls": {
-        return respond(
-          id,
-          languageService.provideCallHierarchyIncomingCalls(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "provideCallHierarchyOutgoingCalls": {
-        return respond(
-          id,
-          languageService.provideCallHierarchyOutgoingCalls(
-            request.specifier,
-            request.position,
-          ),
-        );
-      }
-      case "provideInlayHints":
-        return respond(
-          id,
-          languageService.provideInlayHints(
-            request.specifier,
-            request.span,
-            request.preferences,
-          ),
-        );
       default:
+        if (typeof languageService[method] === "function") {
+          // The `getCompletionEntryDetails()` method returns null if the
+          // `source` is `null` for whatever reason. It must be `undefined`.
+          if (method == "getCompletionEntryDetails") {
+            args[4] ??= undefined;
+          }
+          return respond(id, languageService[method](...args));
+        }
         throw new TypeError(
           // @ts-ignore exhausted case statement sets type to never
-          `Invalid request method for request: "${request.method}" (${id})`,
+          `Invalid request method for request: "${method}" (${id})`,
         );
     }
   }
diff --git a/cli/tsc/compiler.d.ts b/cli/tsc/compiler.d.ts
index 30e4334050..73298a44b7 100644
--- a/cli/tsc/compiler.d.ts
+++ b/cli/tsc/compiler.d.ts
@@ -56,239 +56,4 @@ declare global {
       ...args: any[]
     ): void;
   }
-
-  type LanguageServerRequest =
-    | Restart
-    | ConfigureRequest
-    | FindRenameLocationsRequest
-    | GetAssets
-    | GetApplicableRefactors
-    | GetEditsForRefactor
-    | GetEditsForFileRename
-    | GetCodeFixes
-    | GetCombinedCodeFix
-    | GetCompletionDetails
-    | GetCompletionsRequest
-    | GetDefinitionRequest
-    | GetDiagnosticsRequest
-    | GetDocumentHighlightsRequest
-    | GetEncodedSemanticClassifications
-    | GetImplementationRequest
-    | GetNavigateToItems
-    | GetNavigationTree
-    | GetOutliningSpans
-    | GetQuickInfoRequest
-    | FindReferencesRequest
-    | GetSignatureHelpItemsRequest
-    | GetSmartSelectionRange
-    | GetSupportedCodeFixes
-    | GetTypeDefinitionRequest
-    | PrepareCallHierarchy
-    | ProvideCallHierarchyIncomingCalls
-    | ProvideCallHierarchyOutgoingCalls
-    | ProvideInlayHints;
-
-  interface BaseLanguageServerRequest {
-    id: number;
-    method: string;
-  }
-
-  interface ConfigureRequest extends BaseLanguageServerRequest {
-    method: "configure";
-    // deno-lint-ignore no-explicit-any
-    compilerOptions: Record<string, any>;
-  }
-
-  interface FindRenameLocationsRequest extends BaseLanguageServerRequest {
-    method: "findRenameLocations";
-    specifier: string;
-    position: number;
-    findInStrings: boolean;
-    findInComments: boolean;
-    providePrefixAndSuffixTextForRename: boolean;
-  }
-
-  interface GetAssets extends BaseLanguageServerRequest {
-    method: "getAssets";
-  }
-
-  interface GetApplicableRefactors extends BaseLanguageServerRequest {
-    method: "getApplicableRefactors";
-    specifier: string;
-    range: ts.TextRange;
-    preferences?: ts.UserPreferences;
-    kind: string;
-  }
-
-  interface GetEditsForRefactor extends BaseLanguageServerRequest {
-    method: "getEditsForRefactor";
-    specifier: string;
-    formatCodeSettings: ts.FormatCodeSettings;
-    range: ts.TextRange;
-    refactorName: string;
-    actionName: string;
-    preferences?: ts.UserPreferences;
-  }
-
-  interface GetEditsForFileRename extends BaseLanguageServerRequest {
-    method: "getEditsForFileRename";
-    oldSpecifier: string;
-    newSpecifier: string;
-    formatCodeSettings: ts.FormatCodeSettings;
-    preferences?: ts.UserPreferences;
-  }
-
-  interface GetCodeFixes extends BaseLanguageServerRequest {
-    method: "getCodeFixes";
-    specifier: string;
-    startPosition: number;
-    endPosition: number;
-    errorCodes: string[];
-    formatCodeSettings: ts.FormatCodeSettings;
-    preferences: ts.UserPreferences;
-  }
-
-  interface GetCombinedCodeFix extends BaseLanguageServerRequest {
-    method: "getCombinedCodeFix";
-    specifier: string;
-    // deno-lint-ignore ban-types
-    fixId: {};
-    formatCodeSettings: ts.FormatCodeSettings;
-    preferences: ts.UserPreferences;
-  }
-
-  interface GetCompletionDetails extends BaseLanguageServerRequest {
-    method: "getCompletionDetails";
-    args: {
-      specifier: string;
-      position: number;
-      name: string;
-      formatCodeSettings: ts.FormatCodeSettings;
-      source?: string;
-      preferences?: ts.UserPreferences;
-      data?: ts.CompletionEntryData;
-    };
-  }
-
-  interface GetCompletionsRequest extends BaseLanguageServerRequest {
-    method: "getCompletions";
-    specifier: string;
-    position: number;
-    preferences: ts.GetCompletionsAtPositionOptions;
-    formatCodeSettings: ts.FormatCodeSettings;
-  }
-
-  interface GetDiagnosticsRequest extends BaseLanguageServerRequest {
-    method: "getDiagnostics";
-    specifiers: string[];
-  }
-
-  interface GetDefinitionRequest extends BaseLanguageServerRequest {
-    method: "getDefinition";
-    specifier: string;
-    position: number;
-  }
-
-  interface GetDocumentHighlightsRequest extends BaseLanguageServerRequest {
-    method: "getDocumentHighlights";
-    specifier: string;
-    position: number;
-    filesToSearch: string[];
-  }
-
-  interface GetEncodedSemanticClassifications
-    extends BaseLanguageServerRequest {
-    method: "getEncodedSemanticClassifications";
-    specifier: string;
-    span: ts.TextSpan;
-  }
-
-  interface GetImplementationRequest extends BaseLanguageServerRequest {
-    method: "getImplementation";
-    specifier: string;
-    position: number;
-  }
-
-  interface GetNavigateToItems extends BaseLanguageServerRequest {
-    method: "getNavigateToItems";
-    search: string;
-    maxResultCount?: number;
-    fileName?: string;
-  }
-
-  interface GetNavigationTree extends BaseLanguageServerRequest {
-    method: "getNavigationTree";
-    specifier: string;
-  }
-
-  interface GetOutliningSpans extends BaseLanguageServerRequest {
-    method: "getOutliningSpans";
-    specifier: string;
-  }
-
-  interface GetQuickInfoRequest extends BaseLanguageServerRequest {
-    method: "getQuickInfo";
-    specifier: string;
-    position: number;
-  }
-
-  interface FindReferencesRequest extends BaseLanguageServerRequest {
-    method: "findReferences";
-    specifier: string;
-    position: number;
-  }
-
-  interface GetSignatureHelpItemsRequest extends BaseLanguageServerRequest {
-    method: "getSignatureHelpItems";
-    specifier: string;
-    position: number;
-    options: ts.SignatureHelpItemsOptions;
-  }
-
-  interface GetSmartSelectionRange extends BaseLanguageServerRequest {
-    method: "getSmartSelectionRange";
-    specifier: string;
-    position: number;
-  }
-
-  interface GetSupportedCodeFixes extends BaseLanguageServerRequest {
-    method: "getSupportedCodeFixes";
-  }
-
-  interface GetTypeDefinitionRequest extends BaseLanguageServerRequest {
-    method: "getTypeDefinition";
-    specifier: string;
-    position: number;
-  }
-
-  interface PrepareCallHierarchy extends BaseLanguageServerRequest {
-    method: "prepareCallHierarchy";
-    specifier: string;
-    position: number;
-  }
-
-  interface ProvideCallHierarchyIncomingCalls
-    extends BaseLanguageServerRequest {
-    method: "provideCallHierarchyIncomingCalls";
-    specifier: string;
-    position: number;
-  }
-
-  interface ProvideCallHierarchyOutgoingCalls
-    extends BaseLanguageServerRequest {
-    method: "provideCallHierarchyOutgoingCalls";
-    specifier: string;
-    position: number;
-  }
-
-  interface ProvideInlayHints extends BaseLanguageServerRequest {
-    method: "provideInlayHints";
-    specifier: string;
-    span: ts.TextSpan;
-    preferences?: ts.UserPreferences;
-  }
-
-  interface Restart extends BaseLanguageServerRequest {
-    method: "restart";
-  }
 }
diff --git a/cli/tsc/diagnostics.rs b/cli/tsc/diagnostics.rs
index 08fa3e8dab..2963379747 100644
--- a/cli/tsc/diagnostics.rs
+++ b/cli/tsc/diagnostics.rs
@@ -113,10 +113,13 @@ pub struct Diagnostic {
   pub start: Option<Position>,
   pub end: Option<Position>,
   pub message_text: Option<String>,
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub message_chain: Option<DiagnosticMessageChain>,
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub source: Option<String>,
   pub source_line: Option<String>,
   pub file_name: Option<String>,
+  #[serde(skip_serializing_if = "Option::is_none")]
   pub related_information: Option<Vec<Diagnostic>>,
 }