The hooks performance finding matches what I've seen. I run multiple Claude Code agents in parallel on a remote VM and the first thing I learned was that anything blocking in the agent's critical path kills throughput. Even a few hundred milliseconds per hook call compounds fast when you have agents making dozens of tool calls per minute.

The docker-based service pattern is smart too. I went a different direction for my own setup -- tmux sessions with worktree isolation per agent, which keeps things lightweight but means I have zero observability into what each agent is actually doing beyond tailing logs manually. This solves that gap in a way that doesn't add overhead to the agent itself, which is the right tradeoff.

Curious about one thing -- how does the dashboard handle the case where a sub-agent spawns its own sub-agents? Does it track the full tree or just one level deep?

Sub-agent trees are fully tracked by the dashboard. When an agent is spawned, it always has a parent agent id - claude is sending this in the hooks payload. When you mouse over an agent in the dashboard, it shows what agent spawned it. There currently isn't a tree view of agents in the UI, but it would be easy to add. The data is all there.

[Edit] When claude spawns sub-agents, they inherit the parent's hooks. So all sub-agents activity gets logged by default.