diff --git a/web/src/components/assistant-ui/markdown-text.tsx b/web/src/components/assistant-ui/markdown-text.tsx
index 199067890..2f61a17a4 100644
--- a/web/src/components/assistant-ui/markdown-text.tsx
+++ b/web/src/components/assistant-ui/markdown-text.tsx
@@ -6,12 +6,13 @@ import {
     type CodeHeaderProps,
 } from '@assistant-ui/react-markdown'
 import remarkGfm from 'remark-gfm'
+import remarkDisableIndentedCode from '@/lib/remark-disable-indented-code'
 import { cn } from '@/lib/utils'
 import { SyntaxHighlighter } from '@/components/assistant-ui/shiki-highlighter'
 import { useCopyToClipboard } from '@/hooks/useCopyToClipboard'
 import { CopyIcon, CheckIcon } from '@/components/icons'
 
-export const MARKDOWN_PLUGINS = [remarkGfm]
+export const MARKDOWN_PLUGINS = [remarkGfm, remarkDisableIndentedCode]
 
 function CodeHeader(props: CodeHeaderProps) {
     const { copied, copy } = useCopyToClipboard()
diff --git a/web/src/lib/remark-disable-indented-code.ts b/web/src/lib/remark-disable-indented-code.ts
new file mode 100644
index 000000000..833a5cd99
--- /dev/null
+++ b/web/src/lib/remark-disable-indented-code.ts
@@ -0,0 +1,14 @@
+/**
+ * Remark plugin that disables indented code blocks (4-space indent).
+ *
+ * In CommonMark, text indented by 4+ spaces becomes a code block.  This
+ * frequently misparses LLM output where numbered-list items with nested
+ * content or quoted text are indented.  Fenced code blocks (``` … ```)
+ * still work normally.
+ */
+export default function remarkDisableIndentedCode(this: unknown) {
+    const processor = this as { data(key: string, value?: unknown): unknown }
+    const micromarkExtensions = (processor.data('micromarkExtensions') ?? []) as unknown[]
+    micromarkExtensions.push({ disable: { null: ['codeIndented'] } })
+    processor.data('micromarkExtensions', micromarkExtensions)
+}