Let an outside coordinator turn off injected orchestration instructions and get durable thread events #31735

We run T3 Code as the host for several agent threads that an outside coordinator process supervises. The agents bring their own delegation rules, and two gaps make the layers collide:

1. Add a per-project or per-thread setting to omit T3's injected orchestration instructions and the delegate_task tool, so an outside coordinator's own workflow is not overridden (see [Bug]: Host delegation routing overrides an explicit Bash/tmux agent workflow #30663). Today the instructions are added whenever a T3 MCP session exists, and the only per-project switch turns whole providers off.
2. Revive the idea from the closed PR feat(server): tell outside agents when a watched thread needs them #22595: a durable way for an outside process to learn that a thread finished, failed or is waiting, either a webhook per thread or an append-only event log with an ack offset. Today the only options are polling t3 thread show or holding t3_thread_wait open.

We are happy to test a change against our setup.