GitHub Action Entrypoint Detection

What: Automatic detection when Claude Code runs as a GitHub Action

How to use: Set the environment variable in your GitHub workflow:

- name: Run Claude Code
  env:
    CLAUDE_CODE_ACTION: true
  run: claude -p "Review this PR"

Details:

• Accepts flexible values: "1", "true", "yes", "on" (case-insensitive)
• Sets entrypoint to "claude-code-github-action" for proper telemetry
• Enables GitHub Action-specific behavior and logging
• Evidence: yT8() at line 469210, jA() validation at line 3336