## 1. Implementation
- [x] 1.1 Render optional attendees in artifact frontmatter.
- [x] 1.2 Copy meeting-note attendees when writing a new summary.
- [x] 1.3 Preserve existing summary attendees when rewriting a summary.

## 2. Verification
- [x] 2.1 Add behavior tests for copied and preserved attendees.
- [x] 2.2 Run focused tests and strict OpenSpec validation.