Keep Go's build cache in check builds: re-vendor sneak/prompts e3f79c4 (closes #129)

The vendored files are copies from sneak/prompts e3f79c4, with this
repository's own entries kept. The script/ builds pass a new CACHEBUST
value instead of --no-cache, which emptied Go's build cache mount, so
every make test compiled the standard library and every dependency with
-race. Every Dockerfile stage declares ARG CACHEBUST first, so every RUN
step still reruns on an unchanged tree. The steps that compile mount
Go's build cache, and both go test runs keep -count=1. The lint and test
builds write no image. script/bootstrap, script/fmt and script/fmt-check
are the canonical files plus this repository's Go steps.

Model: opus-5-5

script/bootstrap

@@ -2,18 +2,18 @@
 # 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 (not git,
-# make, node, yarn, go, or python). Node is used directly if installed;
-# otherwise a pinned version is installed via nvm (installing nvm
-# itself first, from a hash-verified release archive, never curl | sh).
+# or apk (detected in that order); assumes nothing is present. The
+# installed node is used only when its major version is the pinned one;
+# otherwise (node missing, or another major) the pinned version is
+# installed via nvm (installing nvm itself first, from a hash-verified
+# release archive, never curl | sh), and yarn and the packages are
+# installed under it.
 # golangci-lint is never installed: script/lint runs it in docker.
-#
-# Uncomment the language sections in main() that apply to this repo.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
-# Pinned versions, 2026-07-06. Never "latest" or "lts"; exact versions.
+# 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
@@ -22,6 +22,7 @@ YARN_VERSION="1.22.22"
 
 PKGMGR=""
 SUDO=""
+APT_UPDATED=""
 
 detect_pkgmgr() {
     [ -n "$PKGMGR" ] && return 0
@@ -50,7 +51,14 @@ pkg_install() {
     detect_pkgmgr
     case "$PKGMGR" in
         nix) nix-env -iA "nixpkgs.$1" ;;
-        apt) $SUDO env DEBIAN_FRONTEND=noninteractive apt-get install -y "$2" ;;
+        apt)
+            # Package lists may be empty (fresh images); refresh once per run.
+            if [ -z "$APT_UPDATED" ]; then
+                $SUDO env DEBIAN_FRONTEND=noninteractive apt-get update
+                APT_UPDATED=1
+            fi
+            $SUDO env DEBIAN_FRONTEND=noninteractive apt-get install -y "$2"
+            ;;
         brew) brew install "$3" ;;
         apk) apk add --no-cache "$4" ;;
     esac
@@ -82,7 +90,7 @@ nvm_sh() {
 
 ensure_nvm() {
     [ -s "$HOME/.nvm/nvm.sh" ] && return 0
-    # nvm prerequisites; nvm itself requires bash, so install it too
+    # nvm prerequisites; nvm itself requires bash
     if missing bash; then pkg_install bash bash bash bash; fi
     if missing curl; then pkg_install curl curl curl curl; fi
     if missing git; then pkg_install git git git git; fi
@@ -95,56 +103,68 @@ ensure_nvm() {
     rm -rf "$tmp"
 }
 
+# True when the node on PATH has the pinned major version. Only the
+# major is compared: the Dockerfile stages start from a node 22 alpine
+# image whose exact version is not the pin, and nvm cannot install a
+# prebuilt node on alpine. Another major is not used: the pinned yarn 1
+# prints a deprecation warning under node 24. script/fmt and
+# script/fmt-check carry this function unchanged, to run the yarn
+# installed here.
+node_is_pinned_major() {
+    if ! command -v node >/dev/null 2>&1; then return 1; fi
+    installed="$(node --version)"
+    installed="${installed#v}"
+    [ "${installed%%.*}" = "${NODE_VERSION%%.*}" ]
+}
+
 ensure_node() {
-    if ! missing node; then return 0; fi
+    if node_is_pinned_major; then
+        echo "bootstrap: using node $(node --version)"
+        return 0
+    fi
     ensure_nvm
     nvm_sh "nvm install $NODE_VERSION"
+    nvm_sh "nvm use $NODE_VERSION >/dev/null && \
+        echo \"bootstrap: using node \$(node --version)\""
 }
 
 ensure_yarn() {
+    if ! node_is_pinned_major; then
+        nvm_sh "nvm use $NODE_VERSION >/dev/null && corepack enable && \
+            corepack prepare yarn@$YARN_VERSION --activate"
+        return 0
+    fi
     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
+    if node_is_pinned_major; then
+        yarn install --frozen-lockfile
+    else
         nvm_sh "nvm use $NODE_VERSION >/dev/null && cd \"$ROOT\" && \
             yarn install --frozen-lockfile"
-    else
-        yarn install --frozen-lockfile
     fi
 }
 
 main() {
     cd "$ROOT"
 
-    # Base tooling (every repo)
-    if missing git; then pkg_install git git git git; fi
     if missing make; then pkg_install gnumake make make make; fi
+    if missing git; then pkg_install git git git git; fi
 
-    # ---- JS / docs repos ----
-    # prettier, pinned in package.json and yarn.lock, formats the markdown
     ensure_node
     ensure_yarn
     install_js_deps
 
-    # ---- Go repos ----
     if missing go; then pkg_install go golang go go; fi
     go mod download
 
-    # ---- Python repos ----
-    # if missing python3; then pkg_install python3 python3 python3 python3; fi
-    # python3 -m venv .venv
-    # ./.venv/bin/pip install -e '.[dev]'
-
     echo "bootstrap complete"
 }
 

script/cibuild

@@ -2,9 +2,11 @@
 # script/cibuild: run the CI build. It bootstraps first: a CI runner
 # checks out and runs this and nothing else, and script/fmt-check runs
 # the formatter on the host, which a pristine checkout cannot do.
-# --no-cache for the same reason as script/docker: the gate phases the
-# final stage depends on are RUN steps, and a cached one is a check that
-# did not run.
+# A new CACHEBUST value reruns every RUN step, since a cached gate phase
+# is a check that did not run; unlike --no-cache, it keeps Go's build cache.
+# This relies on every stage of the Dockerfile declaring ARG CACHEBUST
+# first; a stage without that line is served from cache on an unchanged
+# tree, with no warning.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -14,15 +16,17 @@ main() {
     cd "$ROOT"
     "$SCRIPT_DIR/bootstrap"
     "$SCRIPT_DIR/check"
-    # Own line: a failing command substitution inside an argument does
-    # not trip `set -e`, so the inline form degrades silently to an
-    # empty constant. The VERSION build argument takes precedence over
-    # the version a build stage derives from the .git in the context.
+    # The version and the tag each get their own line: a failing
+    # command substitution inside an argument does not trip `set -e`,
+    # so the inline form degrades silently to an empty constant. The
+    # VERSION build argument takes precedence over the version a build
+    # stage derives from the .git in the context.
     version="$(git describe --tags --always --dirty 2>/dev/null || true)"
     [ -n "$version" ] || version="unknown"
-    docker build --no-cache \
+    tag="$("$SCRIPT_DIR/projectname")"
+    docker build --build-arg CACHEBUST="$(date +%s)-$$" \
         --build-arg VERSION="$version" \
-        -t "$("$SCRIPT_DIR/projectname")" .
+        -t "$tag" .
 }
 
 main "$@"

script/docker

@@ -1,8 +1,11 @@
 #!/bin/sh
 # script/docker: build the Docker image tagged with the project name.
 # Identical in all repos; the tag comes from script/projectname.
-# --no-cache because the gate phases the final stage depends on are RUN
-# steps, and a cached one is a check that did not run.
+# A new CACHEBUST value reruns every RUN step, since a cached gate phase
+# is a check that did not run; unlike --no-cache, it keeps Go's build cache.
+# This relies on every stage of the Dockerfile declaring ARG CACHEBUST
+# first; a stage without that line is served from cache on an unchanged
+# tree, with no warning.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -10,15 +13,17 @@ ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    # Own line: a failing command substitution inside an argument does
-    # not trip `set -e`, so the inline form degrades silently to an
-    # empty constant. The VERSION build argument takes precedence over
-    # the version a build stage derives from the .git in the context.
+    # The version and the tag each get their own line: a failing
+    # command substitution inside an argument does not trip `set -e`,
+    # so the inline form degrades silently to an empty constant. The
+    # VERSION build argument takes precedence over the version a build
+    # stage derives from the .git in the context.
     version="$(git describe --tags --always --dirty 2>/dev/null || true)"
     [ -n "$version" ] || version="unknown"
-    docker build --no-cache \
+    tag="$("$SCRIPT_DIR/projectname")"
+    docker build --build-arg CACHEBUST="$(date +%s)-$$" \
         --build-arg VERSION="$version" \
-        -t "$("$SCRIPT_DIR/projectname")" .
+        -t "$tag" .
 }
 
 main "$@"

script/fmt

@@ -8,15 +8,25 @@ 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.
+# True when the node on PATH has the pinned major version: the same
+# function as in script/bootstrap, which uses it to decide where it
+# installs yarn.
+node_is_pinned_major() {
+    if ! command -v node >/dev/null 2>&1; then return 1; fi
+    installed="$(node --version)"
+    installed="${installed#v}"
+    [ "${installed%%.*}" = "${NODE_VERSION%%.*}" ]
+}
+
+# Run the yarn script/bootstrap installed: the yarn on PATH when the
+# node on PATH has the pinned major version, and otherwise yarn under
+# the pinned node in nvm, which bootstrap leaves off the PATH of the
+# shell that called it. nvm is a bash script, hence the subshell.
 run_yarn() {
-    if command -v yarn >/dev/null 2>&1; then
+    if node_is_pinned_major && command -v yarn >/dev/null 2>&1; then
         exec yarn "$@"
     fi
-    if [ ! -s "$HOME/.nvm/nvm.sh" ]; then
+    if node_is_pinned_major || [ ! -s "$HOME/.nvm/nvm.sh" ]; then
         echo "fmt: no yarn; run script/bootstrap first" >&2
         exit 1
     fi

script/fmt-check

@@ -8,15 +8,25 @@ 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.
+# True when the node on PATH has the pinned major version: the same
+# function as in script/bootstrap, which uses it to decide where it
+# installs yarn.
+node_is_pinned_major() {
+    if ! command -v node >/dev/null 2>&1; then return 1; fi
+    installed="$(node --version)"
+    installed="${installed#v}"
+    [ "${installed%%.*}" = "${NODE_VERSION%%.*}" ]
+}
+
+# Run the yarn script/bootstrap installed: the yarn on PATH when the
+# node on PATH has the pinned major version, and otherwise yarn under
+# the pinned node in nvm, which bootstrap leaves off the PATH of the
+# shell that called it. nvm is a bash script, hence the subshell.
 run_yarn() {
-    if command -v yarn >/dev/null 2>&1; then
+    if node_is_pinned_major && command -v yarn >/dev/null 2>&1; then
         exec yarn "$@"
     fi
-    if [ ! -s "$HOME/.nvm/nvm.sh" ]; then
+    if node_is_pinned_major || [ ! -s "$HOME/.nvm/nvm.sh" ]; then
         echo "fmt-check: no yarn; run script/bootstrap first" >&2
         exit 1
     fi

script/install-precommit

@@ -1,7 +1,6 @@
 #!/bin/sh
 # script/install-precommit: install the git pre-commit hook that runs
 # script/precommit. Our own extension to scripts-to-rule-them-all.
-# Generic: needs no adaptation.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"

script/lint

@@ -5,9 +5,12 @@
 # make its answer untrustworthy.
 #
 # The phase is not the last stage in the file, so it is built only when
-# --target names it. --no-cache because a cached lint layer is a lint
-# that did not run. The tag makes each build replace the previous image
-# instead of leaving a dangling one behind.
+# --target names it. A new CACHEBUST value reruns every RUN step, since
+# a cached lint layer is a lint that did not run; unlike --no-cache, it
+# keeps Go's build cache. This relies on every stage of the Dockerfile
+# declaring ARG CACHEBUST first; a stage without that line is served
+# from cache on an unchanged tree, with no warning.
+# --output type=cacheonly writes no image, since nothing uses one.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -15,9 +18,9 @@ ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    docker build --no-cache \
+    docker build --build-arg CACHEBUST="$(date +%s)-$$" \
         --target lint \
-        -t "$("$SCRIPT_DIR/projectname")-lint" .
+        --output type=cacheonly .
 }
 
 main "$@"

script/setup

@@ -1,7 +1,6 @@
 #!/bin/sh
 # script/setup: set up the repo for development after a fresh clone:
-# installs dependencies (script/bootstrap) and the git pre-commit hook.
-# Add any repo-specific initialization (db init, .env template) here.
+# installs dependencies and the git pre-commit hook.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"

script/test

@@ -2,8 +2,12 @@
 # script/test: run the test suite. Testing is a phase of the Dockerfile
 # and this builds that phase alone, on the same terms as script/lint:
 # --target because a phase that is not the last stage is built only when
-# named, --no-cache because a cached test layer is a test that did not
-# run, and a tag so each build replaces the previous image.
+# named, and a new CACHEBUST value because a cached test layer is a test
+# that did not run; unlike --no-cache, it keeps Go's build cache. This
+# relies on every stage of the Dockerfile declaring ARG CACHEBUST first;
+# a stage without that line is served from cache on an unchanged tree,
+# with no warning. --output type=cacheonly writes no image, since
+# nothing uses one.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -11,9 +15,9 @@ ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    docker build --no-cache \
+    docker build --build-arg CACHEBUST="$(date +%s)-$$" \
         --target test \
-        -t "$("$SCRIPT_DIR/projectname")-test" .
+        --output type=cacheonly .
 }
 
 main "$@"