- Include model in session list output (eliminates N+1 reads)
- Add jq error handling in Supervisor dispatch_ready_beads
- Use process substitution in Supervisor to avoid subshell variable scope
- Fix claude backend Execute to return error (commands go through PTY)
- Make createSubtask return childID (eliminates duplicate O(n) scan)
Fixes: bd-1z2, bd-73r, bd-cid, bd-viu, bd-vdi