Migrate coding agent sessions across 18 harnesses (Claude Code, Codex, Pi, OpenCode, Copilot, Antigravity, Vibe, Muse, Qwen, Kimi, Cursor, etc.)
DeepSeek Harness plugin for previewable cross-preset session migration. Fixed-schema handoffs preserve state, source-model intent, and unresolved images; the original session stays untouched.