The dev Docker Compose uses named volumes (langgraph-venv, gateway-venv)
to persist .venv across container restarts. Docker only populates named
volumes from the image on first creation — subsequent rebuilds do NOT
refresh existing volume contents.
When new dependencies are added to packages/harness/pyproject.toml
(e.g. langchain-anthropic), the stale named volume still contains
the old .venv missing the new packages, causing ModuleNotFoundError
at runtime.
Add `uv sync` before launching both gateway and langgraph services.
When deps are already satisfied this is a no-op (~1s), but when the
volume is stale it installs missing packages before the service starts.
Fixes#1624
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
b21792d9be