[BUG] Invalid Version: 2.1.0 (2026-01-07) /$bunfs/root/claude:810:8909

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?

Title: Invalid Version error when running Claude Code in Windsurf IDE
Description:
Running Claude Code inside Windsurf IDE throws a semver parsing error on startup.
Error:
ERROR Invalid Version: 2.1.0 (2026-01-07)
Root Cause:
The version string 2.1.0 (2026-01-07) is being passed to the semver library, but the date suffix in parentheses makes it invalid. Semver expects the format X.Y.Z without additional text.
Environment:

Claude Code version: 2.1.0
IDE: Windsurf
OS: Windows with WSL2

Stack trace excerpt:
RO (/$bunfs/root/claude:810:8909)
Aq0 (/$bunfs/root/claude:810:14035)
Jq0 (/$bunfs/root/claude:810:14587)
The error originates in the SemVer constructor when parsing the version string.
Expected behavior:
Claude Code should either strip the date suffix before parsing, or use a version string without the date appended.

What Should Happen?

When Claude Code reads or constructs its version string, it should pass only the semver-compliant portion (2.1.0) to the semver library for parsing/comparison operations.
The date suffix (2026-01-07) can be retained for display purposes (e.g., in --version output or logs), but must be stripped before any semver operations like:

Version comparison
Version validation
Range checking

Possible fixes:

Strip the date before parsing - Use a regex like /^(\d+\.\d+\.\d+)/.exec(versionString)[1] to extract just the semver portion before passing to the semver library
Store separately - Keep the version (2.1.0) and build date (2026-01-07) as separate values, only combining them for display
Use semver build metadata - If the date needs to be part of the version string, use the semver-compliant format: 2.1.0+20260107 (build metadata after + is ignored in comparisons)

Error Messages/Logs

ERROR  Invalid Version: 2.1.0 (2026-01-07)

/$bunfs/root/claude:810:8909

Stack trace:
 - RO (/$bunfs/root/claude:810:8909)
 - Aq0 (/$bunfs/root/claude:810:14035)
 - Jq0 (/$bunfs/root/claude:810:14587)
 - <anonymous> (/$bunfs/root/claude:3022:4324)
 -     at sort (unknown)
 - tYD (/$bunfs/root/claude:3022:4310)
 - P6D (/$bunfs/root/claude:3022:13859)
 - _4 (/$bunfs/root/claude:690:20692)
 - Qf (/$bunfs/root/claude:690:39063)
 - ms (/$bunfs/root/claude:690:49670)

Error occurs in SemVer constructor when parsing version string:

class RO{constructor(H,$){
  // ...
  if(!A)throw TypeError(`Invalid Version: ${H}`);
  // ...
}}

The semver library expects format "X.Y.Z" but receives "2.1.0 (2026-01-07)" which fails the regex validation against the FULL or LOOSE semver patterns.

Steps to Reproduce

1. Install Windsurf IDE
2. Install Claude Code CLI (npm install -g @anthropic-ai/claude-code or via the recommended installation method)
3. Open Windsurf IDE
4. Open the integrated terminal within Windsurf
5. Run claude to start Claude Code
6. Error immediately appears on startup before the interactive prompt loads

Note: The issue appears to be specific to running Claude Code within Windsurf's integrated terminal environment. Claude Code may work correctly when run directly from a standalone WSL2/terminal session outside of Windsurf.

Claude Model

Other

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.0 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

windsurf-diagnostics_abbreviated.txt