[BUG] Standalone number-period lines (e.g. 8.) are invisible — markdown renderer collapses empty ordered list items

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When Claude's response contains a standalone line that matches markdown ordered list syntax (<number>. or <number>)), the Claude Code terminal renderer interprets it as an empty ordered list item and collapses it to nothing. The content is completely invisible — only the response bullet (●) renders with no text after it.

This commonly occurs when asking simple math questions and receiving a bare numeric answer like 6. or 8.. Bold wrapping (8.) does not prevent the issue. The bug is independent of output style — tested on both the default style and a custom output style with identical results.

Affected patterns (all invisible):

• 8., 1., 0., 123. — standard ordered list syntax
• 8) — alternate ordered list syntax
• 8. — bold does not escape list parsing
• Multiple lines (1. / 2. / 3.) — all collapse

Working patterns (all visible):

• 8 — no period
• 8. apples — list item has content after marker
• The answer is 8. That is correct. — inline, not parsed as block list
• hello — not a number pattern

What Should Happen?

1. on a standalone line should render as the literal text "8.", not be parsed as an ordered list item with no content. The full response text should always be visible to the user.

Error Messages/Logs

No error messages or stack traces. The content silently disappears from the rendered output.

Steps to Reproduce

1. Open Claude Code in any terminal
2. Prompt: respond with only: 8.
3. Observe that the response bullet (●) renders but no text content appears after it
4. Prompt: respond with only: 8
5. Observe that 8 renders correctly
6. Prompt: respond with only: 8. apples
7. Observe that 8. apples renders correctly
8. Prompt: what is 4+4
9. If Claude responds with 8. on its own line, the answer is invisible

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.45 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

The issue occurs both when the number-period is the entire response and when it appears as a standalone line within a longer response. This was systematically tested with 10 different patterns across two output styles to isolate the root cause to the markdown renderer.

The renderer appears to parse any standalone <number>. or <number>) line as a markdown ordered list item. Since there is no text content after the list marker, the list item is empty and collapses to nothing visually. The response bullet ● still renders, but with no content beside it.