[BUG] Desktop app Markdown view resolves relative image paths against the project root instead of the Markdown file's folder

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

In the Claude desktop app (Code tab), the file pane's Markdown view resolves relative image paths against the session's project root instead of against the folder of the Markdown file.

For a file at proposals/doc.md with images in proposals/images/:

| Markdown | Desktop app | GitHub / IntelliJ |
|---|---|---|
| ![x](images/a.png) (relative to the file) | not rendered | rendered |
| ![x](./images/a.png) | not rendered | rendered |
| ![x](proposals/images/a.png) (relative to the project root) | rendered | not rendered |
| ![x](/absolute/path/proposals/images/a.png) | rendered | rendered (locally) |

So no relative path renders both in the desktop app and in GitHub/IDEs.

What Should Happen?

Relative image paths should resolve against the folder of the Markdown file, as in CommonMark renderers, GitHub and JetBrains IDEs, so the same file shows its images everywhere.

Error Messages/Logs

None - the image is simply not shown.

Steps to Reproduce

1. In a project opened in the Code tab, create docs/sub/img.png (any image) and next to it docs/sub/test.md:

```markdown


```

1. Open docs/sub/test.md in the app's file pane.
2. Only c is shown. On GitHub or in IntelliJ, only a and b are shown.

Use a different image per line when testing: an image loaded once (e.g. via an absolute path) can also appear for another reference to the same file name, which hides the problem.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.285 (Claude Code), Claude desktop app 2.19675.0

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

macOS 26.6.2. Observed in the desktop app's Code tab file pane, not in a terminal.