What probably matters to youSection of the release
What
Fenced code blocks tagged mermaid are turned into rendered diagram blocks wherever Claude Code emits formatted output, such as artifacts and pull request bodies. Rendering used to depend on a runtime probe for diagram support, which could silently leave diagrams as plain code; that probe is gone and the language tag on the fence is now the only condition checked.
Details
The rendering option defaults to true instead of to the result of a support check, so diagrams appear unless something deliberately opts out.
A caller passing mermaidOn: false still disables rendering and leaves the fence as ordinary code.
A matching fence is emitted as a <pre class="mermaid"> block for the diagram renderer to pick up.
Evidence
<pre class="mermaid">, mermaidOn
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
