Semver parser fails on cache/changelog.md heading format

Summary

Claude Code 2.1.0 fails to start due to semver parsing error on its own changelog cache file.

Environment

• Claude Code version: 2.1.0
• Platform: macOS Darwin 24.6.0
• Shell: zsh

Error

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

Stack Trace

/$bunfs/root/claude:813:8909
...
- Pw (/$bunfs/root/claude:813:8909)
- CfD (/$bunfs/root/claude:813:14035)

Root Cause

The file ~/.claude/cache/changelog.md line 3 contains:

## 2.1.0 (2026-01-07)

The semver parser receives 2.1.0 (2026-01-07) (with date annotation) instead of strict semver 2.1.0.

Reproduction

1. Use Claude Code 2.1.0
2. Have ~/.claude/cache/changelog.md present with version heading containing date
3. Start Claude Code with skills enabled
4. Observe startup failure

Workaround

mv ~/.claude/cache/changelog.md ~/.claude/cache/changelog.md.backup

Suggested Fix

1. Validate version strings are strict semver before parsing
2. Skip changelog files in version extraction
3. Or sanitize heading format: extract only semver portion

Additional Context

Discovered during fleet management operations. Multiple agents affected until cache file was renamed.

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Filed by private-work-supervisor-AGET v3.2.1