Mermaid diagrams never render: artifact side panel shows raw HTML as text (macOS, VS Code terminal)

[PetarVukovic]

First off — I use jcode daily and it's great. This is the one papercut I keep hitting.

Problem

When the model produces a mermaid diagram, it never renders visually for me. The artifact side panel shows the raw HTML markup as plain text (<div>, <svg>, … printed literally) instead of a diagram or any readable fallback.

I'm genuinely unsure whether I'm missing a setting on my side or whether this is a bug, hence the issue rather than a PR.

Environment

• jcode v0.76.0 (bbef1f6a8)
• macOS (Darwin 25.2.0), Apple Silicon
• Terminal: VS Code integrated terminal — TERM=xterm-256color, TERM_PROGRAM=vscode

What I expect

I understand the VS Code terminal supports no inline image protocol (no kitty, no iTerm2, no Sixel), so I don't expect a real rendered diagram there. But I'd expect one of:

1. the documented half-block / text fallback with the TERMINAL_IMAGE_FALLBACK_NOTE message, or
2. at minimum the original mermaid source, which is readable,

instead of the generated HTML wrapper dumped as text — that's the least useful of the three, since it's neither a picture nor something a human reads.

Questions

• Is there a config flag or env var to pick the fallback renderer explicitly for terminals with no image protocol?
• Is native rendering in the artifact side panel expected to work at all in the VS Code terminal, or is a graphics-capable terminal (Ghostty / kitty / WezTerm / iTerm2) a hard requirement? If it's a hard requirement, saying so in the docs would already save people the guesswork.

Related

• [Windows Terminal] Native mermaid/inline image rendering via Sixel (WT_SESSION detection missing) #955 — Windows Terminal Sixel detection (WT_SESSION missing from infer_protocol_from_env). Same family of problem (protocol detection falling through to a fallback), but that one is Windows-specific; this is the macOS / VS Code terminal path and the fallback output itself.
• Add Linux font fallbacks for Mermaid SVG text rendering #371 — Linux font fallbacks for mermaid SVG text.

Happy to provide a repro session, logs, or test a patch.

[1jehuang]

Thanks for the detailed report. Could you share a minimal session that reproduces this, the relevant [display]/image-rendering configuration, and a trace or screenshot showing whether the side panel receives generated HTML or Mermaid source? That will let us pin down whether this is the renderer or fallback path.

--- — Jcode agent (automated triage), on behalf of @1jehuang