[BUG] VS Code extension with version 2.1.51 (anthropic.claude-code-2.1.51-win32-x64) fails to activate on Windows

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?

• VS Code extension with version 2.1.51 (anthropic.claude-code-2.1.51-win32-x64) fails to activate on Windows
• Error: TypeError: The argument 'filename' must be a file URL object... with a hardcoded Linux CI path

(file:///home/runner/work/claude-cli-internal/...) baked into extension.js

• Workaround: downgrade to 2.1.49

What Should Happen?

Claude extension should load in VS Code

Error Messages/Logs

2026-02-23 19:52:36.836 [error] Activating extension Anthropic.claude-code failed due to an error:
2026-02-23 19:52:36.836 [error] TypeError: 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 Module.createRequire (node:internal/modules/cjs/loader:1915:13)
    at Object.<anonymous> (c:\Users\dansteve\.vscode\extensions\anthropic.claude-code-2.1.51-win32-x64\extension.js:45:4602)
    at Module._compile (node:internal/modules/cjs/loader:1714:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1848:10)
    at Module.load (node:internal/modules/cjs/loader:1448:32)
    at Module._load (node:internal/modules/cjs/loader:1270:12)
    at c._load (node:electron/js2c/node_init:2:17993)
    at e._load (file:///c:/Users/dansteve/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:405:6055)
    at t._load (file:///c:/Users/dansteve/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:223:22773)
    at s._load (file:///c:/Users/dansteve/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:215:24706)
    at TracingChannel.traceSync (node:diagnostics_channel:328:14)
    at wrapModuleLoad (node:internal/modules/cjs/loader:244:24)
    at Module.require (node:internal/modules/cjs/loader:1470:12)
    at Module.require (c:\Users\dansteve\.vscode\extensions\github.copilot-chat-0.37.8\dist\extension.js:382:36169)
    at require (node:internal/modules/helpers:147:16)
    at pee.Cb (file:///c:/Users/dansteve/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:254:1256)

Steps to Reproduce

1 .load VS Code

1. click Claude button or have a Claude session trying to auto-start
2. observe nothing happens
3. look at console logs for error

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.49

Claude Code Version

2.1.51

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_