[BUG] v2.1.129 VSCode extension fails to activate on Windows due to hardcoded CI build path

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?

After upgrading the Claude Code VSCode extension to v2.1.129 on Windows, the
extension fails to activate. The Claude Code sidebar never renders when I click
the activity bar icon, and the Developer Tools console reports an activation
error caused by what appears to be a Linux absolute path from the GitHub
Actions build runner being passed to a Node filesystem API at runtime.

The path in the error message — /home/runner/work/claude-cli-internal/claude-cli-internal/build-agent-sdk/sdk.mjs
— is the standard GitHub Actions workspace layout (/home/runner/work/...),
which strongly suggests a build-time absolute path was baked into the published
sdk.mjs loader instead of being resolved relative to the extension's install
directory. On Linux CI this "works" because the path literally exists during
the build; on a Windows user machine it is neither a valid Windows path nor a
usable local file URL, so Node throws ERR_INVALID_ARG_TYPE and activation
aborts.

Downgrading to v2.1.123 fully restores functionality, confirming this is a
regression introduced in v2.1.129.

What Should Happen?

The extension should activate normally on Windows after installing v2.1.129,
and the Claude Code sidebar should load just like it does on v2.1.128.

Internally, the loader for sdk.mjs should resolve the file path relative to
the extension's install directory (e.g. via __dirname / import.meta.url at
runtime), not embed an absolute build-machine path captured at bundle time.

Error Messages/Logs

From `Help → Toggle Developer Tools → Console`:


Activating extension 'Anthropic.claude-code' failed: The argument 'filename'
must be a file URL object, file URL string, or absolute path string.
Received 'file:///home/runner/work/claude-cli-internal/claude-cli-internal/build-agent-sdk/sdk.mjs'.
    at $onExtensionActivationError (workbench.desktop.main.js:sourcemap:1031)

Steps to Reproduce

1. Use Windows (tested on Windows 10 Enterprise LTSC 2021, build 10.0.19044).
2. Open VSCode with the Claude Code extension installed at v2.1.128 or earlier

(working baseline).

1. Allow VSCode to auto-update the extension to v2.1.129, OR manually install

v2.1.129 from the Marketplace.

1. Reload the VSCode window (Developer: Reload Window).
2. Click the Claude Code icon in the activity bar to open the sidebar.

Observed: the sidebar fails to render and the activation error above appears
in the Developer Tools console.

To confirm it is version-specific:

1. Open the Extensions panel, click the gear icon on Claude Code →

Install Another Version... → select v2.1.128.

1. Reload the window.
2. The sidebar loads normally and the extension activates without error.

No project-specific code or repo is required to reproduce — the failure
happens at extension activation time, before any workspace code is touched.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.129

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

Environment

• OS: Windows 10 Enterprise LTSC 2021 (10.0.19044)
• Extension: Anthropic.claude-code v2.1.129 (broken) / v2.1.128 (works)
• Reproduces on a fresh VSCode window with no workspace open, so this is not

workspace- or project-specific.

Suspected root cause
The substring /home/runner/work/claude-cli-internal/claude-cli-internal/
in the error is the standard GitHub Actions runner workspace path. A
build-time absolute path appears to have been captured into the shipped
bundle. The fix is likely in whatever code constructs the file:// URL or
filename argument for sdk.mjs — it should be derived at runtime from the
extension's own install location, not from a value resolved during the build.

Platforms not yet tested
I have not verified macOS or Linux. The bug may be Windows-specific simply
because POSIX hosts can sometimes tolerate a stray absolute Linux path, while
Windows cannot. Worth a quick cross-platform check during the fix.

Workaround for other affected users

• Extensions panel → Claude Code → gear icon → Install Another Version...

→ pick v2.1.123 → Reload Window.

• Disable auto-update on the extension until a fixed version ships, otherwise

VSCode will silently re-upgrade back to the broken build.

Happy to attach the full extension host log or Output → Claude Code channel
contents if useful — just let me know which would help most.