Vega-lite rendering issues in Marktest

[Astraeus-Design]

Hi
I have installed Marktest via flatpak on linux mint and have also had it installed using the debian package, both behave the same. The problem I'm having is that mermaid diagrams seem to work fine from cutting and pasting examples, the vega-lite examples either show as a code block, syntactically highlighted, or as a blank box with a frontmatter reference before and after the empty box/fence. In both instances a box appears below with an error I believe stating < Invalid Sequence Codes >. I've added an image of the example taken from the Marktest user docs

I checked the package.json and it has vega-embed as a dependency so am I missing something, do I have to install a Vega server process or something external to Marktest?

Hope someone can help as I wanted to avoid using VScode for markdown as it seems overkill, yet it may be the logical path.

Best Regards
Martyn

[yhay81]

You do not need a Vega server or any separately installed Vega package. MarkText renders Vega-Lite inside Electron with bundled JavaScript dependencies.

The confusing part is the error text. In the released v0.17.1 code, the diagram renderer catches errors from vega-lite, but its fallback message labels every non-flowchart failure as “Sequence”:
https://github.com/marktext/marktext/blob/v0.17.1/src/muya/lib/parser/render/index.js#L129-L167

So < Invalid Sequence Codes > here really means “the Vega-Lite JSON parse/embed failed”; it does not mean MarkText selected a remote sequence-diagram service. v0.17.1's own package manifest includes vega, vega-embed, and vega-lite (5.2.0):
https://github.com/marktext/marktext/blob/v0.17.1/package.json#L64-L66

First test in Source Code Mode with the exact minimal example shipped in the MarkText docs—no start after the language name, no surrounding <pre>, and no extra outer fence:

```vega-lite
{
  "data": {"values": [
    {"a": "C", "b": 2}, {"a": "D", "b": 7}, {"a": "E", "b": 4}
  ]},
  "mark": "point",
  "encoding": {
    "x": {"field": "a", "type": "nominal"},
    "y": {"field": "b", "type": "quantitative"}
  }
}
```

The source for that documented syntax is here:
https://github.com/marktext/marktext/blob/v0.17.1/docs/MARKDOWN_SYNTAX.md#diagrams

Your screenshot uses the current Vega-Lite grouped-bar example with xOffset. MarkText 0.17.1 is pinned to an early Vega-Lite 5.x build, while the current Vega-Lite gallery now serves a v6 spec. Testing the small point chart above removes that version difference.

• If the point chart renders, the installation is fine; the grouped-bar spec is incompatible with the Vega-Lite version bundled by that MarkText release. Use an older v5-compatible spec or a current development build.
• If the point chart still fails in both the Flatpak and Debian package, this is a MarkText v0.17.1 renderer/package bug, not a missing server. Launch MarkText from a terminal (and, if available, open Electron DevTools) to capture the actual JSON/Vega exception—the released UI discards it and shows the misleading Sequence message.

Also make sure the opening fence uses the language identifier exactly vega-lite. If it only appears as a highlighted ordinary code block, the identifier was not recognized (usually because text such as start or copied HTML was included in the fence header).

[Astraeus-Design]

I've sent a couple of replies but they have been returned, they were via email in response to the above received email so I'll give an update. I have been using V0.19 for my tests throughout and I've now used the simple chart suggested with pure text cut n paste. It always inserts "start" after the vega-lite when it renders as syntactically highlighted vega code instead of rendering the chart/graph, I don't add that text myself. The "Sequence" error remains the same throughout but at least we know that is ambiguous and just indicates an error in the underlying rendering process. I shall see if I can catch the rejected error via terminal or, I assume, turn on the developer tools and catch it there. Am I right to believe that the developer tools are in essence like the F12 browser tools in Chrome etc, I'm not familiar with Electron but it appears to be based on Chromium.

Thanks for your help and input.