Install node, yarn and python from the distribution (closes #146)

Follows sneak's ruling at
#146 (comment). Runtimes
and the installer tools bundled with python come from the distribution,
with no version and no hash. Third-party packages stay pinned by hash.

script/bootstrap drops nvm and corepack. It installs node, yarn and the
node packages only when yarn.lock is in the tree, and stops there when
yarn's major version is not 1. This repository's Dockerfile starts from
Alpine 3.24. The Python example starts from debian:trixie-slim, keeps
pipenv at $HOME/.pipenv on a host and in an image, and sets
PIP_ONLY_BINARY=:all:, so pip downloads no build tools without a hash
check.

Model: opus-5-5

.dockerignore

@@ -35,12 +35,6 @@
 # `services/api/.claude/` and must add its own anchored entry.
 .claude
 
-# yarn's install state and cache stay out, and its release file stays
-# in. Docker obeys the last matching line, so these two lines sit above
-# the secret patterns, which must win under .yarn/releases/.
-.yarn/*
-!.yarn/releases
-
 # Environment files. `*.env` covers bare `.env` and the `prod.env`
 # convention. Re-include a committed template with a negation if the
 # build needs one: `!docs/example.env`.

.gitattributes

@@ -2,6 +2,3 @@
 # both sides instead of conflicting. Git never reports a conflict here: read
 # the merged entries after every merge or rebase.
 TODO.md merge=union
-
-# yarn's release file is one opaque file in diffs and merges.
-.yarn/releases/** binary

.gitignore

@@ -19,12 +19,10 @@ Thumbs.db
 
 # Node
 node_modules/
-.yarn/*
-!.yarn/releases
 
-# Secrets. Unanchored, so each matches at every depth. Matching is
-# case-sensitive on Linux, so names use character ranges rather than a
-# lowercase form that misses `Server.Key`.
+# Secrets. Unanchored like every entry above, so each matches at every
+# depth. Matching is case-sensitive on Linux, so names use character
+# ranges rather than a lowercase form that misses `Server.Key`.
 
 # Environment files. `*.env` covers bare `.env` and the `prod.env`
 # convention. Only the templates `example.env` and `sample.env` are

.prettierignore

@@ -1,3 +1,2 @@
 node_modules/
-.yarn/
 yarn.lock

.yarnrc.yml

@@ -1,5 +0,0 @@
-enableTelemetry: false
-
-nodeLinker: node-modules
-
-yarnPath: .yarn/releases/yarn-4.18.1.cjs

Dockerfile

@@ -6,20 +6,17 @@
 # system packages. script/ passes a new value on every build. That value
 # reruns every RUN step below the ARG line, and the install step keeps
 # its layer. node and yarn come from the distribution, which is trusted,
-# so they need no version and no hash. That yarn only starts the release
-# file in .yarn/releases/, so every stage copies that file and
-# .yarnrc.yml before it runs script/bootstrap.
+# so they need no version and no hash.
 #
 # alpine 3.24.3, 2026-11-04
 FROM alpine@sha256:be2656061b536c1883c4034790e21d0a09c5aaaf51968b89368a3c0371ea2c9a AS lint
-RUN apk add --no-cache git make nodejs-current yarn
+RUN apk add --no-cache git make nodejs yarn
 ARG CACHEBUST
 
 WORKDIR /app
 
 COPY script/ script/
-COPY package.json yarn.lock .yarnrc.yml ./
-COPY .yarn/releases/ .yarn/releases/
+COPY package.json yarn.lock ./
 RUN script/bootstrap
 
 COPY . .
@@ -30,14 +27,13 @@ RUN yarn run prettier --check '**/*.md' --tab-width 4 --prose-wrap always
 #
 # alpine 3.24.3, 2026-11-04
 FROM alpine@sha256:be2656061b536c1883c4034790e21d0a09c5aaaf51968b89368a3c0371ea2c9a AS test
-RUN apk add --no-cache git make nodejs-current yarn
+RUN apk add --no-cache git make nodejs yarn
 ARG CACHEBUST
 
 WORKDIR /app
 
 COPY script/ script/
-COPY package.json yarn.lock .yarnrc.yml ./
-COPY .yarn/releases/ .yarn/releases/
+COPY package.json yarn.lock ./
 RUN script/bootstrap
 
 COPY . .
@@ -52,7 +48,7 @@ RUN echo "No tests defined."
 #
 # alpine 3.24.3, 2026-11-04
 FROM alpine@sha256:be2656061b536c1883c4034790e21d0a09c5aaaf51968b89368a3c0371ea2c9a
-RUN apk add --no-cache git make nodejs-current yarn
+RUN apk add --no-cache git make nodejs yarn
 ARG CACHEBUST
 
 WORKDIR /app
@@ -63,8 +59,7 @@ COPY --from=test /app/package.json /dev/null
 # script/bootstrap finds the system packages above and installs the node
 # packages.
 COPY script/ script/
-COPY package.json yarn.lock .yarnrc.yml ./
-COPY .yarn/releases/ .yarn/releases/
+COPY package.json yarn.lock ./
 RUN script/bootstrap
 
 COPY . .

README.md

@@ -111,7 +111,7 @@ development workflow, and the Makefile targets are thin shims that call them.
 The scripts are POSIX sh (not bash) so they run in minimal containers such as
 alpine. We provide:
 
-- `script/bootstrap` — install all dependencies (`yarn install --immutable`)
+- `script/bootstrap` — install all dependencies (yarn install)
 - `script/setup` — set up the repo for development after a fresh clone: runs
   `script/bootstrap`, then `script/install-precommit`
 - `script/projectname` — output the project name (our own extension); used by

TODO.md

@@ -21,40 +21,6 @@ fmt-check, and commit.
 
 # Completed Steps
 
-- 2026-11-06: Compacted `prompts/REPO_POLICIES.md` from 1,145 lines and 8,427
-  words to 1,066 lines and 7,812 words
-  (https://git.eeqj.de/sneak/prompts/issues/158). Every rule keeps its meaning.
-  The rules now sit under headings, the pinning rule first. Each rule that was
-  stated in several places is stated once. The Makefile copies of the Go and
-  Python test commands are gone, because the `Dockerfile` examples carry the
-  same commands. Both checklists name the `.golangci.yml` section.
-- 2026-11-06: The pinning rule in `prompts/REPO_POLICIES.md` now opens with its
-  scope: what we download and install ourselves in scripts and Dockerfiles
-  (https://git.eeqj.de/sneak/prompts/issues/154). Distribution packages are
-  outside the rule, and updating and upgrading them is allowed. Both checklists
-  say the same.
-- 2026-11-04: Each repository now commits yarn 4 and installs with
-  `yarn install --immutable` (https://git.eeqj.de/sneak/prompts/issues/149), on
-  sneak's ruling at
-  https://git.eeqj.de/sneak/prompts/issues/149#issuecomment-167558. Product
-  repositories convert when they next have work. These changed:
-    - This repository carries `.yarn/releases/yarn-4.18.1.cjs`, and its
-      `yarn.lock` is in yarn 4's format.
-    - `script/bootstrap` no longer stops on yarn's major version.
-    - Node comes from the distribution's newest Node package, which on Alpine
-      3.24 is `nodejs-current`.
-    - A `Dockerfile` stage that needs yarn also copies `.yarnrc.yml` and
-      `.yarn/releases/`, and may start from any distribution that packages node
-      and yarn.
-    - Both checklists give the steps, and the ignore files keep yarn's install
-      state out of git and the build context.
-- 2026-11-04: An agent whose work is confined to one package may run `go test`
-  directly on that package's suite, or on individual tests in it, while
-  iterating (https://git.eeqj.de/sneak/prompts/issues/51), on sneak's ruling at
-  https://git.eeqj.de/sneak/prompts/issues/51#issuecomment-167600. The full
-  `make check` is still required before every push, and the `Makefile` gains
-  nothing. The rule on Docker now names the lint and test gates, because a run
-  while iterating is not one.
 - 2026-11-04: node, yarn, npm, python, pip and venv now come from the
   distribution with no version and no hash
   (https://git.eeqj.de/sneak/prompts/issues/146), on sneak's ruling at

package.json

@@ -2,6 +2,5 @@
   "private": true,
   "devDependencies": {
     "prettier": "3.8.1"
-  },
-  "packageManager": "yarn@4.18.1"
+  }
 }

prompts/EXISTING_REPO_CHECKLIST.md

@@ -1,6 +1,6 @@
 ---
 title: Existing Repo Checklist
-last_modified: 2026-11-06
+last_modified: 2026-11-04
 ---
 
 Use this checklist when beginning work in a repo that may not yet conform to our
@@ -163,40 +163,11 @@ with your task.
     - [ ] Go: `go.mod`, `go.sum`, `.golangci.yml` (fetch from
           `https://git.eeqj.de/sneak/prompts/raw/branch/main/.golangci.yml` and,
           in the same commit, set the lint phase digest to the one named in the
-          `.golangci.yml` section of `REPO_POLICIES.md`)
-    - [ ] JS: `package.json`, `yarn.lock`, `.yarnrc.yml`, `.yarn/releases/`,
-          `.gitattributes`, `.prettierrc`, `.prettierignore` (fetch the last two
-          from `https://git.eeqj.de/sneak/prompts/raw/branch/main/.prettierrc`
-          and
-          `https://git.eeqj.de/sneak/prompts/raw/branch/main/.prettierignore`).
-    - [ ] Any repository with `yarn.lock`: that file is in yarn 4's format. If
-          its second line says `yarn lockfile v1`, convert it with the steps
-          below. Do them in one commit with the re-vendored scripts, because
-          yarn 1 ignores `--immutable` and exits 0 on a tree with no
-          `.yarnrc.yml`. Run them with any distribution's node and yarn, and use
-          `yarnpkg` on Debian and Ubuntu.
-        1. Read the version from `yarnPath` in
-           `https://git.eeqj.de/sneak/prompts/raw/branch/main/.yarnrc.yml`.
-        2. Run `yarn set version <version>`. It writes
-           `.yarn/releases/yarn-<version>.cjs`, `yarnPath` in `.yarnrc.yml`, and
-           `packageManager` in `package.json`.
-        3. Add `nodeLinker: node-modules` and `enableTelemetry: false` to
-           `.yarnrc.yml`.
-        4. Run `yarn install` once. It converts `yarn.lock`, and each package
-           keeps its version and gains a `checksum`.
-        5. Delete `approvedGitRepositories`, `enableScripts` and
-           `npmMinimalAgeGate` from `.yarnrc.yml`. The conversion wrote them.
-           They allow install scripts, any git repository and packages of any
-           age, which yarn otherwise refuses.
-        6. In `package.json`, name any package that must run its install script,
-           as `"dependenciesMeta": { "<name>": { "built": true } }`, and run
-           `yarn install` again.
-        7. Add `.yarn/*` and `!.yarn/releases` above the secret patterns in
-           `.gitignore` and `.dockerignore`. Docker obeys the last matching
-           line, and the secret patterns must win. Add `.yarn/` to
-           `.prettierignore`, and `.yarn/releases/** binary` to
-           `.gitattributes`.
-        8. Run `yarn install --immutable`. It must pass and change nothing.
+          `.golangci.yml` paragraph of `REPO_POLICIES.md`)
+    - [ ] JS: `package.json`, `yarn.lock`, `.prettierrc`, `.prettierignore`
+          (fetch from
+          `https://git.eeqj.de/sneak/prompts/raw/branch/main/.prettierrc` and
+          `https://git.eeqj.de/sneak/prompts/raw/branch/main/.prettierignore`)
     - [ ] Python: `pyproject.toml`
     - [ ] Docs/writing: `.prettierrc`, `.prettierignore` (same URLs as above)
 
@@ -233,18 +204,15 @@ with your task.
       installed.
 - [ ] `script/bootstrap` installs node, yarn and the node packages only when
       `yarn.lock` is in the tree. node and yarn come from the distribution when
-      they are missing. It installs the node packages with
-      `yarn install --immutable`. The distribution's yarn only starts the
-      release file that `yarnPath` in `.yarnrc.yml` names, and that file does
-      the work.
-- [ ] A `Dockerfile` stage that needs yarn may start from any distribution that
-      packages node and yarn. It copies `package.json`, `yarn.lock`,
-      `.yarnrc.yml` and `.yarn/releases/` before it runs `script/bootstrap`. A
-      stage that needs no yarn copies none of them.
+      they are missing. With `yarn.lock` in the tree, `script/bootstrap` stops
+      with a one-line message when yarn's major version is not 1.
+- [ ] A `Dockerfile` stage copies `yarn.lock` before it runs `script/bootstrap`
+      only if that stage needs yarn. A stage that needs yarn starts from an
+      image whose distribution packages yarn 1, such as Alpine.
 - [ ] `script/bootstrap`, `script/fmt` and `script/fmt-check` run yarn by
       whichever name is present: `yarn`, or `yarnpkg` on Debian and Ubuntu. With
-      neither name on `PATH`, `script/fmt` and `script/fmt-check` print one line
-      saying to run `script/bootstrap`, and exit 1.
+      neither name on `PATH`, they print one line saying to run
+      `script/bootstrap`, and exit 1.
 - [ ] `script/bootstrap` installs no linter of its own — delete the block, its
       version variables and its call site. A JS repo's `yarn install` stays; it
       brings a linter along with every other dependency, and no verdict is taken
@@ -267,21 +235,17 @@ with your task.
 
 - [ ] Pre-commit hook is installed (`make hooks`)
 - [ ] No secrets in the repo (`.env`, keys, credentials)
-- [ ] No mutable references (tags, `@latest`) to what the repo downloads and
-      installs itself in scripts and Dockerfiles — all pinned by cryptographic
-      hash with version/date comment. Distribution packages are outside this
-      rule. They need no version and no hash, and updating and upgrading them is
-      fine too. In a `Dockerfile`, the distribution is the pinned base image's.
-      On a host, it is the host's, and the host's package manager stands for it,
-      nix and brew included. A package source that a `Dockerfile` adds itself is
-      not the distribution's own, so its packages are pinned
+- [ ] No mutable references in Dockerfiles or scripts (tags, `@latest`) — all
+      pinned by cryptographic hash with version/date comment. The one exception
+      is a package from the distribution's own package index, which needs no
+      version and no hash. Pulling that index is also allowed. In a
+      `Dockerfile`, the distribution is the pinned base image's. On a host, it
+      is the host's, and the host's package manager stands for it, nix and brew
+      included. A package source that a `Dockerfile` adds itself does not get
+      this exception
 - [ ] node, yarn, npm, python, pip and venv come from the distribution wherever
       possible, never from nvm, pyenv, corepack or `npm install -g yarn`. If the
-      distribution's version is too old, use a newer distribution. node means
-      the distribution's newest Node package, such as `nodejs-current` on Alpine
-      3.24
-- [ ] yarn's release file is in git under `.yarn/releases/`, written once by
-      `yarn set version` with an exact version (repositories with `yarn.lock`)
+      distribution's version is too old, use a newer distribution
 - [ ] Using `yarn`, not `npm` (JS projects)
 
 # Directory Structure

prompts/NEW_REPO_CHECKLIST.md

@@ -1,6 +1,6 @@
 ---
 title: New Repo Checklist
-last_modified: 2026-11-06
+last_modified: 2026-11-04
 ---
 
 Use this checklist when creating a new repository from scratch. Follow the steps
@@ -178,23 +178,8 @@ Template files can be fetched from:
     - [ ] Go: `go mod init sneak.berlin/go/<name>`, `.golangci.yml` (fetch from
           `https://git.eeqj.de/sneak/prompts/raw/branch/main/.golangci.yml` and,
           in the same commit, set the lint phase digest to the one named in the
-          `.golangci.yml` section of `REPO_POLICIES.md`)
-    - [ ] JS, or any repository that runs prettier through yarn: make the first
-          `yarn.lock` with the steps below. `script/bootstrap` installs no yarn
-          until `yarn.lock` exists, so run them with any distribution's node and
-          yarn, such as Alpine's (`apk add nodejs-current yarn`). Use `yarnpkg`
-          on Debian and Ubuntu.
-        1. Read the version from `yarnPath` in
-           `https://git.eeqj.de/sneak/prompts/raw/branch/main/.yarnrc.yml`.
-        2. Run `yarn set version <version>`. It writes
-           `.yarn/releases/yarn-<version>.cjs`, `.yarnrc.yml` and
-           `package.json`.
-        3. Add `nodeLinker: node-modules` and `enableTelemetry: false` to
-           `.yarnrc.yml`.
-        4. Add `"private": true` to `package.json`.
-        5. Run `yarn add --dev prettier`. It writes `yarn.lock`.
-        6. Add `.yarn/releases/** binary` to `.gitattributes`.
-        7. Run `yarn install --immutable`. It must pass and change nothing.
+          `.golangci.yml` paragraph of `REPO_POLICIES.md`)
+    - [ ] JS: `yarn init`, `yarn add --dev prettier`
     - [ ] Python: `pyproject.toml`
 
 ## Configure script/ Entrypoints and Makefile
@@ -211,17 +196,15 @@ are thin shims calling them. Model scripts:
     - It installs node, yarn and the node packages only when `yarn.lock` is in
       the tree. node and yarn come from that package manager when they are
       missing.
-    - It installs the node packages with `yarn install --immutable`. The
-      distribution's yarn only starts the release file that `yarnPath` in
-      `.yarnrc.yml` names, and that file does the work.
+    - With `yarn.lock` in the tree, it stops with a one-line message when yarn's
+      major version is not 1.
     - A non-server repo's development environment stage runs it, with only
       system packages installed inline above it.
     - A gate phase or the build stage installs what its base image lacks, either
       inline or by running it.
-- [ ] A `Dockerfile` stage that needs yarn may start from any distribution that
-      packages node and yarn. It copies `package.json`, `yarn.lock`,
-      `.yarnrc.yml` and `.yarn/releases/` before it runs `script/bootstrap`. A
-      stage that needs no yarn copies none of them.
+- [ ] A `Dockerfile` stage copies `yarn.lock` before it runs `script/bootstrap`
+      only if that stage needs yarn. A stage that needs yarn starts from an
+      image whose distribution packages yarn 1, such as Alpine.
 - [ ] `script/setup` / `make setup` — readies a fresh clone: runs `bootstrap`,
       then `install-precommit`, plus repo-specific init
 - [ ] `script/test` / `make test` —
@@ -253,8 +236,8 @@ are thin shims calling them. Model scripts:
       `script/fmt-check` runs the formatter on the host.
 - [ ] `script/bootstrap`, `script/fmt` and `script/fmt-check` run yarn by
       whichever name is present: `yarn`, or `yarnpkg` on Debian and Ubuntu. With
-      neither name on `PATH`, `script/fmt` and `script/fmt-check` print one line
-      saying to run `script/bootstrap`, and exit 1.
+      neither name on `PATH`, they print one line saying to run
+      `script/bootstrap`, and exit 1.
 - [ ] No `docker build` in `script/` leaves a dangling image behind:
       `script/lint` and `script/test` write no image, and `script/docker` and
       `script/cibuild` tag theirs
@@ -285,20 +268,15 @@ are thin shims calling them. Model scripts:
       final stage is missing its `COPY --from=` edge to the gate phases.
 - [ ] No secrets in repo, and none in the build context: enumerate a probe image
       rather than reading `.dockerignore`
-- [ ] No mutable references to what the repo downloads and installs itself in
-      scripts and Dockerfiles. Distribution packages are outside this rule. They
-      need no version and no hash, and updating and upgrading them is fine too.
-      In a `Dockerfile`, the distribution is the pinned base image's. On a host,
-      it is the host's, and the host's package manager stands for it, nix and
-      brew included. A package source that a `Dockerfile` adds itself is not the
-      distribution's own, so its packages are pinned
+- [ ] No mutable image/package references. The one exception is a package from
+      the distribution's own package index, which needs no version and no hash.
+      Pulling that index is also allowed. In a `Dockerfile`, the distribution is
+      the pinned base image's. On a host, it is the host's, and the host's
+      package manager stands for it, nix and brew included. A package source
+      that a `Dockerfile` adds itself does not get this exception
 - [ ] node, yarn, npm, python, pip and venv come from the distribution wherever
       possible, never from nvm, pyenv, corepack or `npm install -g yarn`. If the
-      distribution's version is too old, use a newer distribution. node means
-      the distribution's newest Node package, such as `nodejs-current` on Alpine
-      3.24
-- [ ] yarn's release file is in git under `.yarn/releases/`, written once by
-      `yarn set version` with an exact version (repositories with `yarn.lock`)
+      distribution's version is too old, use a newer distribution
 - [ ] No unnecessary files in repo root
 - [ ] All dates written as YYYY-MM-DD
 

script/bootstrap

@@ -4,10 +4,8 @@
 # installed tools are skipped. Base tools, node and yarn come from nix,
 # apt, brew, or apk (detected in that order), with no version and no
 # hash, because the distribution is trusted. It installs node, yarn and
-# the node packages only when yarn.lock is in the tree. The
-# distribution's yarn only starts the release file that yarnPath in
-# .yarnrc.yml names, and that file does the work. So git pins the yarn
-# that runs. Assumes nothing is present.
+# the node packages only when yarn.lock is in the tree. Assumes nothing
+# is present.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
@@ -80,12 +78,21 @@ main() {
 
     # A Dockerfile stage that needs no yarn copies no yarn.lock.
     if [ -f yarn.lock ]; then
-        if missing node; then pkg_install nodejs_latest nodejs node nodejs-current; fi
+        if missing node; then pkg_install nodejs nodejs node nodejs; fi
         if missing yarn && missing yarnpkg; then
             pkg_install yarn yarnpkg yarn yarn
         fi
 
-        run_yarn install --immutable
+        # Debian 13 and Ubuntu 26.04 package yarn 4, which refuses a yarn 1
+        # yarn.lock, or rewrites it in its own format.
+        yarn_version="$(run_yarn --version)"
+        if [ "${yarn_version%%.*}" != "1" ]; then
+            echo "bootstrap: yarn $yarn_version refuses this yarn 1 yarn.lock;" \
+                "use a distribution that packages yarn 1" >&2
+            exit 1
+        fi
+
+        run_yarn install --frozen-lockfile
     fi
 
     echo "bootstrap complete"

yarn.lock

@@ -1,23 +1,8 @@
-# This file is generated by running "yarn install" inside your project.
-# Manual changes might be lost - proceed with caution!
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
 
-__metadata:
-  version: 10
-  cacheKey: 10c0
 
-"prettier@npm:3.8.1":
-  version: 3.8.1
-  resolution: "prettier@npm:3.8.1"
-  bin:
-    prettier: bin/prettier.cjs
-  checksum: 10c0/33169b594009e48f570471271be7eac7cdcf88a209eed39ac3b8d6d78984039bfa9132f82b7e6ba3b06711f3bfe0222a62a1bfb87c43f50c25a83df1b78a2c42
-  languageName: node
-  linkType: hard
-
-"root-workspace-0b6124@workspace:.":
-  version: 0.0.0-use.local
-  resolution: "root-workspace-0b6124@workspace:."
-  dependencies:
-    prettier: "npm:3.8.1"
-  languageName: unknown
-  linkType: soft
+prettier@3.8.1:
+  version "3.8.1"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-3.8.1.tgz#edf48977cf991558f4fcbd8a3ba6015ba2a3a173"
+  integrity sha512-UOnG6LftzbdaHZcKoPFtOcCKztrQ57WkHDeRD9t/PTQtmT0NHSeWWepj6pS0z/N7+08BHFDQVUrfmfMRcZwbMg==