Desktop file panel can't open markdown links with spaces or commas in path

The in-app file viewer in Claude Code desktop fails to open files when a clickable markdown link's href contains spaces or commas, regardless of encoding. Plain ASCII paths open fine.

Environment

• Claude Code desktop app (macOS)
• Working directory contains files with spaces and commas in filenames (Obsidian vault)

Repro

In a session whose working directory contains a file at Topics/Agentic Development Practices.md, have the model emit any of these link forms:

1. URL-encoded: [Agentic Development Practices](Topics/Agentic%20Development%20Practices.md)
2. CommonMark angle-bracket: [Agentic Development Practices](<Topics/Agentic Development Practices.md>)
3. Same patterns with a comma in the filename, e.g. Side Projects/.../Non-developers can now build production software with AI tools, changing the design process.md

Click the rendered link.

Expected

File opens in the right-hand file panel, same as it does for paths without special characters.

Actual

File panel shows: "File could not be read. It may have been deleted or moved, or it lives outside the session folder."

A second rendering bug compounds it: the comma case also splits visually, with .md getting auto-linkified into a phantom http://...md URL.

What works

Plain relative paths with no special characters open correctly:

[2026-04-24](Journal/2026/04/2026-04-24.md) ✅

Why it matters

For users whose working directories contain human-readable filenames (notes vaults, design docs, anything with spaces or punctuation), the model can't produce clickable references — forcing a copy-paste workaround.