deploy_topology and teardown_topology are async, but every
_compose_with_retry / _compose call inside them was running in the
main event loop via subprocess.run — which means a multi-minute
docker compose --build froze the entire API: other endpoints,
mutator events, SSE streams, status polls. The user noticed when a
2-decky deploy blocked everything else for the duration of the build.
Wrap both calls in anyio.to_thread.run_sync. Same pattern the
mutator engine has been using at engine.py:104 since forever.
Per-LAN bridge create/remove docker SDK calls are still synchronous
in the loop — they're individually fast (~50-200ms per LAN) and
the loops are bounded by topology size, so they don't dominate.
Worth revisiting if a 200-LAN deploy turns out to stall noticeably.
anti
99bc9a8b6d