claude-code - 💡(How to fix) Fix Markdown renderer errors on [[double-bracket]] wikilink syntax in tool call output [1 comments, 2 participants]

Claude Code's terminal markdown renderer fails to handle an AST node when rendering bash tool call content that contains [[double-bracket]] wikilink syntax. The error message Unhandled node type: string appears between Claude's output text and the permission prompt. Any bash tool call whose command text contains [[double-bracket]] wikilink syntax triggers the error. For example, a heredoc writing Obsidian-style markdown with [[wikilinks]]:

Note: Screenshot available but cannot be uploaded via CLI. The error Unhandled node type: string appears directly after rendered markdown containing [[wikilink]] syntax, just before the permission prompt. Cosmetic only — tool execution is not affected, writes succeed. But the error message is confusing and clutters the output.

TL;DR

The issue can be resolved by modifying the CommonMark renderer to handle the non-standard [[double-bracket]] wikilink syntax or by escaping the brackets in the markdown content.

Guidance

• Identify the specific part of the CommonMark renderer that is causing the error and update it to recognize the [[double-bracket]] syntax as a valid wikilink.
• Consider adding a preprocessing step to escape the [[double-bracket]] syntax in the markdown content before passing it to the renderer.
• Verify that the error is indeed caused by the [[double-bracket]] syntax by testing the renderer with different inputs.
• If the issue is specific to the Claude Code CLI, check if there are any configuration options or updates available that may address the problem.

Example

# Escaping the brackets as a temporary workaround
obs_put "Page Name" "$(cat <<'PAGEEOF'
## Sources
- \[\[Gemma\]\] — Google DeepMind open-weight model family
- \[\[Qwen3-TTS\]\] — Alibaba/Qwen open-weight speech synthesis family
- \[\[vLLM\]\] — high-throughput inference engine
PAGEEOF
)"

Notes

The solution may require modifications to the CommonMark renderer or the Claude Code CLI, and may involve updating dependencies or configuration files. The exact steps will depend on the specific implementation and requirements of the project.

Recommendation

Apply a workaround, such as escaping the brackets, until a more permanent solution can be implemented, as this will allow the tool to function without displaying the error message.