Fold cmux and herdr agent-multiplexer patterns into TAC loop-engineering guidance. Treat the primary agent as orchestrator over panes/tabs via CLI + socket (no MCP required), pane as isolation boundary, and multiplexer state (working/idle/blocked) as the feedback signal. Keep TAC invariants: deploy stays signed-action-only via git-proxy:8099/deploy, peer agents remain insider-threat candidates with least privilege and receipts, multiplexer driving shells does not grant a raw-command deploy path.