Screenshots leak between concurrent Claude Code sessions

Bug

When running multiple Claude Code sessions concurrently on the same repo, screenshots shared with one session appear in a different session's context. The receiving session has no context for the images and doesn't know why they were sent.

Steps to reproduce

1. Open two Claude Code sessions on the same project
2. Share screenshots with session A (e.g., app screenshots for UI review)
3. Session B receives the screenshots as part of its next message, with no indication they came from session A

Expected behavior

Screenshots should be scoped to the session they were shared with.

Environment

• macOS Darwin 23.6.0
• Claude Code CLI
• Model: claude-opus-4-6 (1M context)