diff --git a/packages/core/src/blocks/defaultBlocks.test.ts b/packages/core/src/blocks/defaultBlocks.test.ts
new file mode 100644
index 0000000000..27b4e5b52e
--- /dev/null
+++ b/packages/core/src/blocks/defaultBlocks.test.ts
@@ -0,0 +1,67 @@
+import { Editor, Extension, getSchema, Mark, Node } from "@tiptap/core";
+import { describe, expect, it } from "vite-plus/test";
+import { CommentMark } from "../comments/mark.js";
+import { NON_FORMATTING_MARK_GROUP } from "../schema/markGroups.js";
+import { defaultStyleSpecs } from "./defaultBlocks.js";
+
+const extensions = [
+  Node.create({ name: "doc", topNode: true, content: "text*" }),
+  Node.create({ name: "text", group: "inline" }),
+  ...Object.values(defaultStyleSpecs).map((style) => style.implementation.mark),
+];
+
+describe("inline code mark exclusions", () => {
+  it.each([false, true])(
+    "builds exclusions from enabled marks (comments enabled: %s)",
+    (withComments) => {
+      const editor = new Editor({
+        element: null,
+        extensions: [
+          ...extensions,
+          Extension.create({
+            name: "customMarks",
+            addExtensions() {
+              return [
+                Mark.create({ name: "customStyle" }),
+                ...(withComments
+                  ? [
+                      CommentMark,
+                      Mark.create({
+                        name: "customAnnotation",
+                        group: NON_FORMATTING_MARK_GROUP,
+                      }),
+                    ]
+                  : []),
+              ];
+            },
+          }),
+        ],
+      });
+
+      try {
+        const { marks } = editor.schema;
+        const code = marks.code;
+        expect(code.spec.excludes).not.toBe("_");
+        for (const mark of Object.values(marks)) {
+          expect(code.excludes(mark)).toBe(
+            !mark.spec.group?.split(" ").includes(NON_FORMATTING_MARK_GROUP),
+          );
+        }
+
+        if (withComments) {
+          const codeMark = code.create();
+          const commentMark = marks.comment.create({ threadId: "thread" });
+          expect(codeMark.addToSet([commentMark])).toHaveLength(2);
+          expect(commentMark.addToSet([codeMark])).toHaveLength(2);
+        }
+      } finally {
+        editor.destroy();
+      }
+    },
+  );
+
+  it("supports schema creation without an editor", () => {
+    const { marks } = getSchema(extensions);
+    expect(marks.code.excludes(marks.bold)).toBe(true);
+  });
+});
diff --git a/packages/core/src/blocks/defaultBlocks.ts b/packages/core/src/blocks/defaultBlocks.ts
index d2eeaa0aa3..9dfd6b2b25 100644
--- a/packages/core/src/blocks/defaultBlocks.ts
+++ b/packages/core/src/blocks/defaultBlocks.ts
@@ -18,6 +18,7 @@ import {
   getInlineContentSchemaFromSpecs,
   getStyleSchemaFromSpecs,
 } from "../schema/index.js";
+import { marksExcludingNonFormattingMarks } from "../schema/markGroups.js";
 import {
   createAudioBlockSpec,
   createBulletListItemBlockSpec,
@@ -139,6 +140,9 @@ export const defaultStyleSpecs = {
   strike: createStyleSpecFromTipTapMark(Strike, "boolean"),
   code: createStyleSpecFromTipTapMark(
     Code.extend({
+      excludes() {
+        return marksExcludingNonFormattingMarks(this.editor);
+      },
       addInputRules() {
         return [
           // Matches any string that starts with a backtick, ends with a
diff --git a/packages/core/src/schema/markGroups.ts b/packages/core/src/schema/markGroups.ts
index 47f03531be..3681cf6f23 100644
--- a/packages/core/src/schema/markGroups.ts
+++ b/packages/core/src/schema/markGroups.ts
@@ -1,4 +1,4 @@
-import { Editor, getExtensionField } from "@tiptap/core";
+import { Editor, flattenExtensions, getExtensionField } from "@tiptap/core";
 
 /**
  * ProseMirror mark group for "non-formatting" marks: comments and the
@@ -36,7 +36,9 @@ export function nonFormattingMarks(editor: Editor | undefined): string {
   if (!editor) {
     return "";
   }
-  const hasNonFormattingMark = editor.options.extensions.some((extension) => {
+  const hasNonFormattingMark = flattenExtensions(
+    editor.options.extensions,
+  ).some((extension) => {
     if (extension.type !== "mark") {
       return false;
     }
@@ -48,3 +50,33 @@ export function nonFormattingMarks(editor: Editor | undefined): string {
   });
   return hasNonFormattingMark ? NON_FORMATTING_MARK_GROUP : "";
 }
+
+/**
+ * The `excludes` field value for marks which may coexist with annotation marks
+ * but should exclude all other marks.
+ *
+ * Returns `"_"` when no editor is available, preserving ProseMirror's default
+ * behavior for schema creation outside an editor.
+ */
+export function marksExcludingNonFormattingMarks(
+  editor: Editor | undefined,
+): string {
+  if (!editor) {
+    return "_";
+  }
+
+  return flattenExtensions(editor.options.extensions)
+    .filter((extension) => {
+      if (extension.type !== "mark") {
+        return false;
+      }
+
+      const group = getExtensionField(extension, "group") as string | undefined;
+      return (
+        typeof group !== "string" ||
+        !group.split(" ").includes(NON_FORMATTING_MARK_GROUP)
+      );
+    })
+    .map((extension) => extension.name)
+    .join(" ");
+}
diff --git a/tests/src/end-to-end/comments/comments.test.tsx b/tests/src/end-to-end/comments/comments.test.tsx
index b5ec2a6267..fd7303ad03 100644
--- a/tests/src/end-to-end/comments/comments.test.tsx
+++ b/tests/src/end-to-end/comments/comments.test.tsx
@@ -1,7 +1,7 @@
 import App from "@examples/07-collaboration/09-comments-testing/src/App";
 import { beforeEach, describe, expect, test, vi } from "vite-plus/test";
 import { render } from "vitest-browser-react";
-import { browserName, page, userEvent } from "../../utils/context.js";
+import { browserName, MOD, page, userEvent } from "../../utils/context.js";
 import { EDITOR_SELECTOR, LINK_BUTTON_SELECTOR } from "../../utils/const.js";
 import {
   expectElement,
@@ -190,6 +190,36 @@ describe("Check Comments functionality", () => {
     ).toBeVisible();
   });
 
+  test("Should preserve existing comments when adding a code mark", async () => {
+    await focusOnEditor();
+
+    await userEvent.keyboard("hello");
+    await doubleClickElement(page.getByText("hello").element());
+
+    await userEvent.click(await waitForSelector('[data-test="addcomment"]'));
+    await waitForSelector(".bn-thread");
+
+    await userEvent.keyboard("test comment");
+    await userEvent.click(await waitForSelector('button[data-test="save"]'));
+
+    // Re-select the commented text and toggle inline code on it (Cmd/Ctrl+E).
+    await doubleClickElement(
+      document.querySelectorAll("span.bn-thread-mark")[0] as HTMLElement,
+    );
+    await userEvent.keyboard(`{${MOD}>}e{/${MOD}}`);
+
+    // The comment must be preserved, and the text must now also be inline code,
+    // i.e. the comment and code marks coexist on the same text.
+    await expectElement(
+      await waitForSelector("span.bn-thread-mark"),
+    ).toBeVisible();
+    await expectElement(
+      await waitForSelector(
+        "span.bn-thread-mark code, code span.bn-thread-mark",
+      ),
+    ).toBeVisible();
+  });
+
   test.skipIf(browserName === "webkit")(
     "Should select thread on first click and open link on second click",
     async () => {