Duplicated IDs for markers (still)

[Bunker-D]

Description

There are still duplicated IDs for the markers in various diagram types, which can cause various formatting issues (such as disappearing arrows). This was the subject of issues #1318, #3267 and #1871, that where closed after the merge #4825 — but arguably wrongfully so for #1318 and #3267.

In fact, the issue was solved for class diagrams, flowcharts and state diagrams, but remains for:

• C4 context diagrams (C4Context)
• Entity Relationship diagrams (erDiagram)
• Requirement diagram (requirementDiagram)
• Sequence diagrams (sequenceDiagram)
• Timelines (timeline) and User journeys (journey).

Steps to reproduce

Any of the aforementioned diagram types. See this issue for a practical case with the associated code. (n this case, the first Mermaid diagram is within a foldable section.)

Screenshots

No response

Code Sample

No response

Setup

No response

Suggested Solutions

The suggested solution would be the same as merge #4825: using the id of the diagram (the SVG element) as a prefix to the markers it defines.

It would probably be a good thing to add classes to the markers for styling purposes. Typically, class="mermaid-<diargame_type>-<marker_old_id>".

🖐 I am already working on it (and it looks like it's working); however, I might need some help with the testing part.

Additional Context

No response