[Bug] Claude Code intercepts and continues external Claude SDK agent sessions

Question

Key Evidence:
  - Custom agent with claude-agent-sdk (python) sessions are logged to ~/.claude/projects/
  - claude --continue resumes external agent sessions
  - Sessions marked as "external" but still continuable
  - Complete breach of session isolation between different Claude SDK applications

This is a significant issue - your private agent conversations are being logged by Claude
  Code, and the two systems aren't properly isolated.

**Environment Info**
- Platform: darwin
- Terminal: cu