Format Markdown with prettier in make fmt (closes #43)

script/fmt and script/fmt-check now run prettier on every Markdown file
after their Go steps, as the standard scripts from sneak/prompts at
dd4027b do. script/bootstrap gains the standard node, nvm and yarn
install next to its goimports install, and the last Dockerfile stage
copies package.json and yarn.lock before running it. .prettierrc,
.prettierignore and yarn.lock are the standard copies. package.json is
the standard one without its licence field and marked private, because
this repo's licence is the WTFPL. .dockerignore keeps the log of a failed
yarn install out of the build context. README.md and TODO.md are
reformatted once with it; REPO_POLICIES.md already matched.

Model: opus-5-5

script/bootstrap

@@ -2,11 +2,21 @@
 # script/bootstrap: install all dependencies needed to build and develop
 # this repo. Idempotent: every install is guarded by a check so already
 # installed tools are skipped. Base tooling comes from nix, apt, brew,
-# or apk (detected in that order); assumes nothing is present.
+# or apk (detected in that order); assumes nothing is present. Node is
+# used directly if installed; otherwise it is installed at a pinned
+# version via nvm (installing nvm itself first, from a hash-verified
+# release archive, never curl | sh).
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
+# Pinned versions, 2026-07-06
+NODE_VERSION="22.17.0"
+NVM_VERSION="0.40.3"
+# sha256 of https://github.com/nvm-sh/nvm/archive/refs/tags/v0.40.3.tar.gz
+NVM_SHA256="5f4d6aaa04a177dc93c985e31dbc411ab6b8c6e1e21d8015dbc1372625fcd1d0"
+YARN_VERSION="1.22.22"
+
 # goimports from golang.org/x/tools v0.30.0, 2025-02-10: the last release
 # that Go 1.22, the Go of go.mod and the Dockerfile, can build.
 GOIMPORTS_COMMIT="09747cdf594a7924dcecb506312be3bd6e437962"
@@ -81,6 +91,69 @@ ensure_goimports() {
     echo "goimports $GOIMPORTS_VERSION at $(command -v goimports)"
 }
 
+# verify_sha256 <file> <expected-hash>
+verify_sha256() {
+    if command -v sha256sum >/dev/null 2>&1; then
+        actual="$(sha256sum "$1" | cut -d' ' -f1)"
+    else
+        actual="$(shasum -a 256 "$1" | cut -d' ' -f1)"
+    fi
+    if [ "$actual" != "$2" ]; then
+        echo "bootstrap: sha256 mismatch for $1" >&2
+        echo "  expected: $2" >&2
+        echo "  actual:   $actual" >&2
+        exit 1
+    fi
+}
+
+# nvm is a bash script; run a command in a bash with nvm loaded
+nvm_sh() {
+    bash -c ". \"\$HOME/.nvm/nvm.sh\" && $*"
+}
+
+ensure_nvm() {
+    [ -s "$HOME/.nvm/nvm.sh" ] && return 0
+    # nvm prerequisites; nvm itself requires bash
+    if missing bash; then pkg_install bash bash bash bash; fi
+    if missing curl; then pkg_install curl curl curl curl; fi
+    if missing git; then pkg_install git git git git; fi
+    tmp="$(mktemp -d)"
+    curl -fsSL -o "$tmp/nvm.tar.gz" \
+        "https://github.com/nvm-sh/nvm/archive/refs/tags/v${NVM_VERSION}.tar.gz"
+    verify_sha256 "$tmp/nvm.tar.gz" "$NVM_SHA256"
+    mkdir -p "$HOME/.nvm"
+    tar -xzf "$tmp/nvm.tar.gz" -C "$HOME/.nvm" --strip-components=1
+    rm -rf "$tmp"
+}
+
+ensure_node() {
+    if ! missing node; then return 0; fi
+    ensure_nvm
+    nvm_sh "nvm install $NODE_VERSION"
+}
+
+ensure_yarn() {
+    if ! missing yarn; then return 0; fi
+    if ! missing corepack; then
+        corepack enable
+        corepack prepare "yarn@$YARN_VERSION" --activate
+    elif [ -s "$HOME/.nvm/nvm.sh" ]; then
+        nvm_sh "nvm use $NODE_VERSION >/dev/null && corepack enable && \
+            corepack prepare yarn@$YARN_VERSION --activate"
+    else
+        npm install -g "yarn@$YARN_VERSION"
+    fi
+}
+
+install_js_deps() {
+    if missing yarn && [ -s "$HOME/.nvm/nvm.sh" ]; then
+        nvm_sh "nvm use $NODE_VERSION >/dev/null && cd \"$ROOT\" && \
+            yarn install --frozen-lockfile"
+    else
+        yarn install --frozen-lockfile
+    fi
+}
+
 main() {
     cd "$ROOT"
 
@@ -93,6 +166,10 @@ main() {
 
     go mod download
 
+    ensure_node
+    ensure_yarn
+    install_js_deps
+
     echo "bootstrap complete"
 }
 

script/fmt

@@ -1,17 +1,37 @@
 #!/bin/sh
-# script/fmt: format all files (writes) with the goimports that
-# script/bootstrap installs. It puts Go's bin directory first on PATH, as
-# script/bootstrap does, so it runs that goimports even when the directory
-# is not on the caller's PATH.
+# script/fmt: format all files (writes): Go with the goimports that
+# script/bootstrap installs, then Markdown with prettier. It puts Go's bin
+# directory first on PATH, as script/bootstrap does, so it runs that
+# goimports even when the directory is not on the caller's PATH.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
+# Must match the pin in script/bootstrap.
+NODE_VERSION="22.17.0"
+
+# script/bootstrap installs node and yarn under nvm and leaves neither
+# on the PATH of the shell that called it, so resolve the pinned
+# toolchain here the way bootstrap's own install step does. nvm is a
+# bash script, hence the subshell.
+run_yarn() {
+    if command -v yarn >/dev/null 2>&1; then
+        exec yarn "$@"
+    fi
+    if [ ! -s "$HOME/.nvm/nvm.sh" ]; then
+        echo "fmt: no yarn; run script/bootstrap first" >&2
+        exit 1
+    fi
+    exec bash -c '. "$HOME/.nvm/nvm.sh" && nvm use "$1" >/dev/null &&
+        shift && exec yarn "$@"' bash "$NODE_VERSION" "$@"
+}
+
 main() {
     cd "$ROOT"
     gobin="$(go env GOBIN)"
     PATH="${gobin:-$(go env GOPATH)/bin}:$PATH"
     goimports -l -w .
+    run_yarn run prettier --write '**/*.md' --tab-width 4 --prose-wrap always
 }
 
 main "$@"

script/fmt-check

@@ -1,10 +1,30 @@
 #!/bin/sh
 # script/fmt-check: check formatting (read-only). Fails and lists the
-# offending files if gofmt would reformat anything.
+# offending files if gofmt would reformat any Go file; otherwise fails if
+# prettier would reformat any Markdown file.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
+# Must match the pin in script/bootstrap.
+NODE_VERSION="22.17.0"
+
+# script/bootstrap installs node and yarn under nvm and leaves neither
+# on the PATH of the shell that called it, so resolve the pinned
+# toolchain here the way bootstrap's own install step does. nvm is a
+# bash script, hence the subshell.
+run_yarn() {
+    if command -v yarn >/dev/null 2>&1; then
+        exec yarn "$@"
+    fi
+    if [ ! -s "$HOME/.nvm/nvm.sh" ]; then
+        echo "fmt-check: no yarn; run script/bootstrap first" >&2
+        exit 1
+    fi
+    exec bash -c '. "$HOME/.nvm/nvm.sh" && nvm use "$1" >/dev/null &&
+        shift && exec yarn "$@"' bash "$NODE_VERSION" "$@"
+}
+
 main() {
     cd "$ROOT"
     unformatted="$(gofmt -l .)"
@@ -13,6 +33,7 @@ main() {
         echo "$unformatted"
         exit 1
     fi
+    run_yarn run prettier --check '**/*.md' --tab-width 4 --prose-wrap always
 }
 
 main "$@"