[BUG] VSCode Extension: Markdown file links with CJK (Chinese/Japanese) characters in filename are not clickable on Linux

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?

Description

When Claude Code responds with markdown file links containing CJK (Chinese, Japanese, Korean) characters in the filename, the links appear as blue hyperlinks in the VS Code extension chat panel but are not clickable — clicking them does nothing.

This issue was previously reported for macOS (#16056) and Japanese filenames (#25426), but both were closed as "not planned" or "duplicate". This report confirms the same bug exists on Ubuntu Linux with Traditional Chinese (繁體中文) filenames, demonstrating this is a cross-platform, cross-language issue affecting all CJK users.

Steps to Reproduce

1. Open a workspace in VS Code with Claude Code extension installed
2. Create a file with CJK characters in its name, e.g. 測試文件.py or 設定檔.json
3. Ask Claude a question that causes it to reference this file
4. Claude responds with a markdown link like [測試文件.py](測試文件.py)
5. The link appears blue and underlined, but clicking it does nothing

Expected Behavior

Clicking the file link should open the file in the VS Code editor, the same way ASCII-only filename links work.

Actual Behavior

• Links with ASCII-only filenames (e.g. main.py, config.json) → Clickable, works correctly
• Links with CJK characters in filename (e.g. 測試文件.py, テスト.py) → Not clickable, nothing happens
• The same markdown link format works correctly when written inside a .md file in the editor (Cmd/Ctrl+click opens the file). The issue is specific to the chat panel output.

Environment

• Platform: Ubuntu Linux (x86_64)
• OS Version: Ubuntu 22.04 LTS
• Claude Code version: Latest
• VS Code: Latest stable
• Extension mode: Webview (not terminal mode)
• Affected languages: Traditional Chinese (繁體中文), also confirmed with Japanese (日本語) in #25426

Workarounds

• Use Ctrl+P (Quick Open) and paste the file path manually
• Click the "Read [file]" or "Edit [file]" action buttons in Claude's thinking section (these work correctly)
• Use terminal mode instead of webview (untested)

Related Issues

• #16056 — Same bug on macOS (closed as "not planned")
• #25426 — Same bug with Japanese filenames on macOS (closed as duplicate of #16056)
• #10846 — Same bug on Windows

Why This Should Be Reopened/Fixed

This bug affects all CJK language users across all platforms (Windows, macOS, Linux). The root cause appears to be how the webview handles vscode.open command URIs for file paths containing non-ASCII characters. Given that CJK languages represent a significant user base, this is a fundamental accessibility issue that should not remain "not planned".

What Should Happen?

Clicking a markdown file link with CJK characters in the filename (e.g. [測試文件.py](測試文件.py)) in the VS Code extension chat panel should open the referenced file in the editor, just like links with ASCII-only filenames do.

Error Messages/Logs

No error messages are displayed. Clicking the link simply produces no response — no file opens, no error in the VS Code developer console related to this action.

Steps to Reproduce

1. Open a workspace in VS Code with the Claude Code extension installed
2. Create a file with CJK characters in its name, e.g. 測試文件.py
3. Ask Claude a question that causes it to reference this file (e.g. "read 測試文件.py")
4. Claude responds with a markdown link like [測試文件.py](測試文件.py)
5. Click the link in the chat panel
6. Nothing happens — the file does not open

For comparison:

1. Create a file with an ASCII-only name, e.g. test.py
2. Ask Claude to reference it
3. Claude responds with [test.py](test.py)
4. Click the link → File opens correctly

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Latest

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

This issue has been reported multiple times across different platforms and CJK languages:

• #16056 (macOS, general markdown links) — closed as "not planned"
• #25426 (macOS, Japanese filenames) — closed as duplicate
• #10846 (Windows) — closed

This new report adds Ubuntu Linux + Traditional Chinese (繁體中文) to the list, confirming this is a universal cross-platform issue for all non-ASCII filenames.

The root cause likely lies in how the webview component handles URI encoding for vscode.open command URIs when file paths contain non-ASCII characters. ASCII-only paths work perfectly, so the link rendering logic itself is correct — only the URI handling for non-ASCII characters is broken.