diff --git a/apps/web/package.json b/apps/web/package.json
index e6980cf778ea..ec7334e1fd86 100644
--- a/apps/web/package.json
+++ b/apps/web/package.json
@@ -32,6 +32,7 @@
     "@tanstack/react-pacer": "^0.19.4",
     "@tanstack/react-router": "^1.160.2",
     "@tiptap/core": "^3.31.3",
+    "@tiptap/extension-code": "^3.31.3",
     "@tiptap/extension-task-item": "^3.31.3",
     "@tiptap/extension-task-list": "^3.31.3",
     "@tiptap/pm": "^3.31.3",
diff --git a/apps/web/src/components/ComposerPromptEditorTiptap.tsx b/apps/web/src/components/ComposerPromptEditorTiptap.tsx
index 5126246dd05c..f8f0b07159fd 100644
--- a/apps/web/src/components/ComposerPromptEditorTiptap.tsx
+++ b/apps/web/src/components/ComposerPromptEditorTiptap.tsx
@@ -46,6 +46,7 @@ import {
   buildDocJson,
   buildTiptapContent,
   collapsedToFlat,
+  ComposerCodeExtension,
   ComposerTaskItemExtension,
   flatToCollapsed,
   flatToMarkdown,
@@ -741,8 +742,9 @@ function ComposerPromptEditorTiptapInner(props: ComposerPromptEditorProps) {
           dropcursor: false,
           gapcursor: false,
           trailingNode: false,
+          code: false,
           // Plain mode has no marks: typed markers stay literal characters.
-          ...(richText ? {} : { bold: false, italic: false, strike: false, code: false }),
+          ...(richText ? {} : { bold: false, italic: false, strike: false }),
         }),
         ComposerMentionExtension,
         ComposerSkillExtension,
@@ -751,6 +753,7 @@ function ComposerPromptEditorTiptapInner(props: ComposerPromptEditorProps) {
         ComposerMarkersExtension,
         ...(richText
           ? [
+              ComposerCodeExtension,
               TaskList,
               ComposerTaskItemExtension.extend({
                 addInputRules() {
diff --git a/apps/web/src/composer-rich-text-doc.test.ts b/apps/web/src/composer-rich-text-doc.test.ts
index a8798708974b..8fa311b1999c 100644
--- a/apps/web/src/composer-rich-text-doc.test.ts
+++ b/apps/web/src/composer-rich-text-doc.test.ts
@@ -7,6 +7,7 @@ import { describe, expect, it } from "vite-plus/test";
 import {
   buildDocJson,
   collapsedToFlat,
+  ComposerCodeExtension,
   ComposerTaskItemExtension,
   flatToCollapsed,
   flatToMarkdown,
@@ -38,7 +39,9 @@ const schema = getSchemaByResolvedExtensions(
       dropcursor: false,
       gapcursor: false,
       trailingNode: false,
+      code: false,
     }),
+    ComposerCodeExtension,
     stubAtom("composer-mention", { path: { default: "" }, source: { default: "" } }),
     stubAtom("composer-skill", {
       skillName: { default: "" },
@@ -64,6 +67,8 @@ const schema = getSchemaByResolvedExtensions(
 function roundTrip(value: string) {
   const json = buildDocJson(value, (name) => ({ label: name, description: null }));
   const doc = ProseMirrorNode.fromJSON(schema, json);
+  // `insertContent` validates every node against the schema; `fromJSON` does not.
+  doc.check();
   return serializeEditorDoc(doc);
 }
 
@@ -135,6 +140,10 @@ describe("composer rich text document model", () => {
     "hello **bold** world",
     "a *italic* word and `code` here",
     "struck ~~out~~ now",
+    "**`x`**",
+    "*`x`*",
+    "~~`x`~~",
+    "**a `code` c**",
     "***bold italic*** keeps nesting",
     "line one\nline two",
     "trailing newline\n",
diff --git a/apps/web/src/composer-rich-text-doc.ts b/apps/web/src/composer-rich-text-doc.ts
index e6cedcc5abb3..ed83c35b5f5b 100644
--- a/apps/web/src/composer-rich-text-doc.ts
+++ b/apps/web/src/composer-rich-text-doc.ts
@@ -1,4 +1,5 @@
 import type { Node as ProseMirrorNode } from "@tiptap/pm/model";
+import { Code } from "@tiptap/extension-code";
 import { TaskItem } from "@tiptap/extension-task-item";
 
 import { splitPromptIntoComposerSegments } from "~/composer-editor-mentions";
@@ -41,6 +42,13 @@ const TIPTAP_TO_MARK: Record<string, RichTextMark> = {
   code: "code",
 };
 
+/**
+ * Tiptap's code mark excludes every other mark, which rejects the `bold+code`
+ * spans markdown like `**\`x\`**` parses into and drops the whole insert.
+ * Code nests inside emphasis here, so it only excludes itself like the rest.
+ */
+export const ComposerCodeExtension = Code.extend({ excludes: "code" });
+
 /**
  * Task list items keep their exact source indent in an attribute so nesting
  * round-trips byte-identically. Checkbox case (`[X]`) normalizes to `[x]` —
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 6feae2edd57c..c052af3c6a1e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -633,6 +633,9 @@ importers:
       '@tiptap/core':
         specifier: ^3.31.3
         version: 3.31.3(@tiptap/pm@3.31.3)
+      '@tiptap/extension-code':
+        specifier: ^3.31.3
+        version: 3.31.3(@tiptap/core@3.31.3(@tiptap/pm@3.31.3))
       '@tiptap/extension-task-item':
         specifier: ^3.31.3
         version: 3.31.3(@tiptap/extension-list@3.31.3(@tiptap/core@3.31.3(@tiptap/pm@3.31.3))(@tiptap/pm@3.31.3))