script/bootstrap kept any yarn on PATH, so YARN_VERSION applied
only where none was installed. It now keeps the yarn on PATH only when
yarn --version is exactly YARN_VERSION, and otherwise installs that
version. The node on PATH is used only when it has the pinned major
version, as REPO_POLICIES.md asks, and is at least NODE_MIN_VERSION.
After installing either, bootstrap looks the tool up through PATH
again, stops, naming the path, if that one fails the same check, and
prints the version it uses, as for Go. Every other host script that
runs yarn now goes through the new script/yarn, which uses the first
node on PATH, ~/.local/bin first, when it passes the same test, and
otherwise the pinned node in nvm.
Model: opus-5-5
No entrypoint could change yarn.lock or go.mod: script/bootstrap
installs with --frozen-lockfile, so adding a package meant running
yarn by hand. make add-dependency PACKAGE=<name>@<version> shims to
the new script/add-dependency: yarn add --dev, then yarn install
--frozen-lockfile. make tidy shims to the new script/tidy, go mod
tidy in backend/; a Go module is added by importing it, or moved by
editing its require line, then make tidy. script/bootstrap is
unchanged.
Model: opus-5-5