diff --git a/apps/vscode/src/extension.ts b/apps/vscode/src/extension.ts
index 251db7b9..b85e7e2b 100644
--- a/apps/vscode/src/extension.ts
+++ b/apps/vscode/src/extension.ts
@@ -23,6 +23,7 @@ import { activateDiagram } from "./providers/diagram/diagram";
 import { activateOptionEnterProvider } from "./providers/option";
 import { textFormattingCommands } from "./providers/text-format";
 import { activateCodeFormatting } from "./providers/format";
+import { activateContextKeySetter } from "./providers/context-keys";
 import { ExtensionHost } from "./host";
 
 export function activateCommon(
@@ -37,6 +38,9 @@ export function activateCommon(
   // background highlighter
   activateBackgroundHighlighter(context, engine);
 
+  // context setter
+  activateContextKeySetter(context, engine);
+
   // diagramming
   const diagramCommands = activateDiagram(context, host, engine);
 
diff --git a/apps/vscode/src/providers/context-keys.ts b/apps/vscode/src/providers/context-keys.ts
new file mode 100644
index 00000000..f639c6a1
--- /dev/null
+++ b/apps/vscode/src/providers/context-keys.ts
@@ -0,0 +1,93 @@
+/*
+ * context-keys.ts
+ *
+ * Copyright (C) 2024 by Posit Software, PBC
+ *
+ * Unless you have received this program directly from Posit Software pursuant
+ * to the terms of a commercial license agreement with Posit Software, then
+ * this program is licensed to you under the terms of version 3 of the
+ * GNU Affero General Public License. This program is distributed WITHOUT
+ * ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING THOSE OF NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Please refer to the
+ * AGPL (http://www.gnu.org/licenses/agpl-3.0.txt) for more details.
+ *
+ */
+
+
+import * as vscode from "vscode";
+import debounce from "lodash.debounce";
+
+import { isQuartoDoc } from "../core/doc";
+import { MarkdownEngine } from "../markdown/engine";
+import { mainLanguage } from "../vdoc/vdoc";
+
+const debounceOnDidChangeDocumentMs = 250;
+
+export function activateContextKeySetter(
+  context: vscode.ExtensionContext,
+  engine: MarkdownEngine
+) {
+
+  // set context keys when docs are opened
+  vscode.workspace.onDidOpenTextDocument(
+    (doc) => {
+      if (doc === vscode.window.activeTextEditor?.document) {
+        if (isQuartoDoc(doc)) {
+          setContextKeys(vscode.window.activeTextEditor, engine);
+        }
+      }
+    },
+    null,
+    context.subscriptions
+  );
+
+  // set context keys when visible text editors change
+  vscode.window.onDidChangeVisibleTextEditors(
+    (_editors) => {
+      triggerUpdateContextKeys(engine);
+    },
+    null,
+    context.subscriptions
+  );
+
+  // set context keys on changes to the document (if its visible)
+  vscode.workspace.onDidChangeTextDocument(
+    (event) => {
+      const visibleEditor = vscode.window.visibleTextEditors.find(editor => {
+        return editor.document.uri.toString() === event.document.uri.toString();
+      });
+      if (visibleEditor) {
+        debounce(
+          () => setContextKeys(visibleEditor, engine),
+          debounceOnDidChangeDocumentMs
+        )();
+      }
+    },
+    null,
+    context.subscriptions
+  );
+
+  // set context keys at activation time
+  triggerUpdateContextKeys(engine);
+
+}
+
+function triggerUpdateContextKeys(engine: MarkdownEngine) {
+  for (const editor of vscode.window.visibleTextEditors) {
+    setContextKeys(editor, engine);
+  }
+}
+
+function setContextKeys(editor: vscode.TextEditor, engine: MarkdownEngine) {
+  if (!editor || !isQuartoDoc(editor.document)) {
+    return;
+  }
+
+  // expose main language for use in keybindings, etc
+  const tokens = engine.parse(editor.document);
+  const language = mainLanguage(tokens);
+  vscode.commands.executeCommand(
+    'setContext',
+    'quarto.document.languageId',
+    language?.ids[0]);
+}