Orchestrator chats: delegate to worker threads without blocking the chat

[BhansaliMadhav]

Hey Theo 👋 First off, I'm a big fan of you and of T3 Code. I built this with a coding agent in a few hours, and I'd love to know whether the direction fits before anyone spends review time on it.

The problem

When I run an orchestrator-style agent that hands work to other agents, it has to block on a wait call (or poll with sleeps) until the sub-agents finish. That ties up the chat, so I can't use it for anything else while the work runs.

The idea: orchestrator chats

• A new chat mode, Orchestrator. It plans the work with you, then starts worker threads through T3 Code MCP tools (spawn_worker, list_workers, get_worker, send_to_worker, interrupt_worker, remove_worker_workspace).
• No waiting. The orchestrator ends its turn after spawning workers. When a worker finishes, fails, or needs the user, the server starts a turn in the orchestrator chat with that news. If the orchestrator is busy, updates wait until it is idle and arrive together.
• Questions go to the user. A worker's questions and approvals reach you in the orchestrator chat, and you answer them in a Workers panel there.
• Where workers run. By default each worker gets its own git worktree on a new branch, and a worker can span several repos. A worker can instead use the project's checkout or an existing worktree, and a setting picks the default.
• Safety. Only the server can create workers. Workspace removal is limited to folders T3 Code created, and borrowed checkouts are never removed.

Branch: https://github.com/BhansaliMadhav/t3code/tree/t3code/orchestrator-async-agent-nudge

PR with the code: #14764. Happy to split it, cut it down, or drop it, whatever direction you prefer.