Install the pinned node when the installed one is another major version (closes #118)

script/bootstrap used whatever node was installed, so on the CI runner
image, which ships node 24, the pinned yarn 1.22.22 printed the
deprecation warning DEP0169 on every bootstrap. It now uses the
installed node only when its major version is the pinned one, and
otherwise installs the pinned node with nvm, as it already did when node
was missing, with yarn and the packages under it. It prints the node
version it uses. Only the major is compared because the Dockerfile
stages use a node 22 alpine image that nvm cannot replace. script/fmt
and script/fmt-check carry the same test to pick their yarn: the yarn on
PATH, or yarn under the pinned node loaded through nvm.

Model: opus-5-5

prompts/REPO_POLICIES.md

@@ -1,6 +1,6 @@
 ---
 title: Repository Policies
-last_modified: 2026-10-07
+last_modified: 2026-10-08
 ---
 
 This document covers repository structure, tooling, and workflow standards. Code
@@ -54,34 +54,39 @@ style conventions are in separate documents:
   `cibuild`. `script/bootstrap` installs all dependencies idempotently and
   assumes nothing is present: base tools come from nix, apt, brew, or apk
   (detected in that order; apt runs noninteractive). For node it uses the
-  installed node if present; otherwise it installs a PINNED node version via
-  nvm, first installing nvm itself if missing — from a hash-verified GitHub
-  release archive (never `curl | sh`), with bash installed as an explicit
-  prerequisite since nvm requires bash. yarn is then pinned via
-  `corepack prepare yarn@<version> --activate`. Never install "latest" or "lts";
-  always exact versions. `script/cibuild` runs the CI build: it changes to the
-  repo root, runs `script/bootstrap`, runs `script/check`, and builds the image
-  with the version; the Gitea workflow calls it. **`script/cibuild` runs
+  installed node only when its major version is the pinned one; otherwise (node
+  missing, or another major, such as the node 24 the CI runner image ships) it
+  installs the PINNED node version via nvm and installs yarn and the packages
+  under it. nvm itself is installed first if missing, from a hash-verified
+  GitHub release archive (never `curl | sh`), with bash installed as an explicit
+  prerequisite since nvm requires bash. Only the major version is compared
+  because the `Dockerfile` stages start from a node image whose exact version is
+  not the pin, and nvm cannot install a prebuilt node on alpine. yarn is pinned
+  via `corepack prepare yarn@<version> --activate`. Never install "latest" or
+  "lts"; always exact versions. `script/cibuild` runs the CI build: it changes
+  to the repo root, runs `script/bootstrap`, runs `script/check`, and builds the
+  image with the version; the Gitea workflow calls it. **`script/cibuild` runs
   `script/bootstrap` first**, because the workflow checks out the repo and runs
   nothing else, while `script/fmt-check` runs the formatter on the host: on a
   pristine checkout with nothing installed the run dies there, after the
-  containerised gates have passed. **The bootstrap alone is not enough**:
-  `script/bootstrap` installs node and yarn under nvm and leaves neither on the
-  `PATH` of the shell that called it, so a bare `yarn` still exits 127. The host
-  entrypoints that need yarn — `script/fmt` and `script/fmt-check` — therefore
-  source nvm for the pinned node version before invoking it, exactly as
-  `script/bootstrap`'s own install step does. A runner carrying nothing but
-  docker and git then gets through `script/check`. Four further scripts are our
-  own extensions to the standard: `script/check` runs `script/test`,
-  `script/lint` and `script/fmt-check`; `script/precommit` is what the git
-  pre-commit hook runs, and it calls `script/check`; `script/install-precommit`
-  installs the git pre-commit hook (the `make hooks` target shims to it); and
-  `script/projectname` (literally that filename) simply outputs the project's
-  name. Scripts that need the name call `script/projectname` — e.g.
-  `script/docker` assembles its image tag from it — so those scripts stay
-  byte-identical across all repos. Repo-type-specific pre-commit extras (e.g.
-  `go mod tidy` verification in Go repos) belong in `script/precommit`, not in
-  the hook itself. Model scripts are at
+  containerised gates have passed. **The bootstrap alone is not enough**: when
+  `script/bootstrap` installs node and yarn under nvm it leaves neither on the
+  `PATH` of the shell that called it, so a bare `yarn` either exits 127 or runs
+  under another node. The host entrypoints that need yarn — `script/fmt` and
+  `script/fmt-check` — therefore use the same test as `script/bootstrap`: when
+  the node on `PATH` has the pinned major version they run the `yarn` on `PATH`,
+  and otherwise they load nvm through `$HOME/.nvm/nvm.sh` and run yarn under the
+  pinned node. A runner carrying nothing but docker and git then gets through
+  `script/check`. Four further scripts are our own extensions to the standard:
+  `script/check` runs `script/test`, `script/lint` and `script/fmt-check`;
+  `script/precommit` is what the git pre-commit hook runs, and it calls
+  `script/check`; `script/install-precommit` installs the git pre-commit hook
+  (the `make hooks` target shims to it); and `script/projectname` (literally
+  that filename) simply outputs the project's name. Scripts that need the name
+  call `script/projectname` — e.g. `script/docker` assembles its image tag from
+  it — so those scripts stay byte-identical across all repos. Repo-type-specific
+  pre-commit extras (e.g. `go mod tidy` verification in Go repos) belong in
+  `script/precommit`, not in the hook itself. Model scripts are at
   `https://git.eeqj.de/sneak/prompts/raw/branch/main/script/<name>`. The README
   must document the provided scripts in an **Entrypoints** section (see the
   README requirements below).
@@ -549,6 +554,11 @@ style conventions are in separate documents:
       function defined and never invoked has the same exit status and the same
       empty output as one that worked.
 
+    Node is the exception to the whole-token comparison: the canonical
+    `script/bootstrap` compares only its major version, because the node 22
+    alpine image the `Dockerfile` stages start from is not the exact pin, and
+    nvm cannot install a prebuilt node on alpine.
+
     Keep it POSIX sh: no arrays, no `[[`, no `grep -P`.
 
     A Go tool a repo needs on the host is installed with `go install` pinned to