.dockerignore

@@ -72,10 +72,12 @@
 **/*.sublime-*
 
 # This repository's host-built artifacts: the example program's binary,
-# test binaries and coverage output.
+# test binaries, coverage output, and the log yarn writes when an install
+# fails.
 /cmd/example/example
 /*.test
 /*.out
+/yarn-error.log
 
 # aider's files, among them a config file that can hold an API key.
 **/.aider*

.prettierignore

@@ -0,0 +1,2 @@
+node_modules/
+yarn.lock

.prettierrc

@@ -0,0 +1,4 @@
+{
+    "tabWidth": 4,
+    "proseWrap": "always"
+}

Dockerfile

@@ -31,6 +31,6 @@ COPY --from=lint /src/go.sum /dev/null
 COPY --from=test /src/go.sum /dev/null
 WORKDIR /src
 COPY script/ script/
-COPY go.mod go.sum ./
+COPY go.mod go.sum package.json yarn.lock ./
 RUN script/bootstrap
 COPY . .

README.md

@@ -3,35 +3,33 @@
 ## Summary
 
 simplelog is an opinionated logging package designed to facilitate easy and
-structured logging in Go applications with an absolute minimum of
-boilerplate.
+structured logging in Go applications with an absolute minimum of boilerplate.
 
-The idea is that you can add a single import line which replaces the
-stdlib `log/slog` default handler, and solve the 90% case for logging.
+The idea is that you can add a single import line which replaces the stdlib
+`log/slog` default handler, and solve the 90% case for logging.
 
 ## Current Status
 
-Released v1.0.0 2024-06-14.  Works as intended.  No known bugs.
+Released v1.0.0 2024-06-14. Works as intended. No known bugs.
 
 ## Features
 
--   if output is a tty, outputs pretty color logs
--   if output is not a tty, outputs json
--   supports delivering each log message via a webhook
--   emits every `slog` attribute: those passed to a log call, those
-    accumulated with `WithAttrs`, and those qualified by `WithGroup`.
-    `slog.Group` values nest, and `slog.LogValuer` values are resolved. In
-    json output attributes are object fields (groups become nested objects);
-    in console output they are appended as `key=value` pairs, with grouped
-    keys written as `group.key=value`. See
-    [Attribute output](#attribute-output) for the details worth knowing
--   reports a record that could not be delivered as an error from the
-    handler's `Handle` method. See
-    [When delivery fails](#when-delivery-fails) for how to receive it
+- if output is a tty, outputs pretty color logs
+- if output is not a tty, outputs json
+- supports delivering each log message via a webhook
+- emits every `slog` attribute: those passed to a log call, those accumulated
+  with `WithAttrs`, and those qualified by `WithGroup`. `slog.Group` values
+  nest, and `slog.LogValuer` values are resolved. In json output attributes are
+  object fields (groups become nested objects); in console output they are
+  appended as `key=value` pairs, with grouped keys written as `group.key=value`.
+  See [Attribute output](#attribute-output) for the details worth knowing
+- reports a record that could not be delivered as an error from the handler's
+  `Handle` method. See [When delivery fails](#when-delivery-fails) for how to
+  receive it
 
 ## Planned Features
 
--   supports delivering logs via tcp RELP (e.g. to remote rsyslog using imrelp)
+- supports delivering logs via tcp RELP (e.g. to remote rsyslog using imrelp)
 
 ## Installation
 
@@ -49,9 +47,9 @@ go get sneak.berlin/go/simplelog
 
 ## Usage
 
-Below is an example of how to use SimpleLog in a Go application. This
-example is provided in the form of a `main.go` file, which demonstrates
-logging at various levels using structured logging syntax.
+Below is an example of how to use SimpleLog in a Go application. This example is
+provided in the form of a `main.go` file, which demonstrates logging at various
+levels using structured logging syntax.
 
 ```go
 package main
@@ -73,63 +71,58 @@ func main() {
 ## Attribute output
 
 Attributes reach every handler: the ones passed to the log call, the ones
-accumulated with `WithAttrs`, and the ones qualified by the groups open at
-the time they were attached. `slog.Group` values nest, and
-`slog.LogValuer` values are resolved to the value they stand for. A few
-behaviours are worth knowing before you rely on them.
+accumulated with `WithAttrs`, and the ones qualified by the groups open at the
+time they were attached. `slog.Group` values nest, and `slog.LogValuer` values
+are resolved to the value they stand for. A few behaviours are worth knowing
+before you rely on them.
 
-**Your values are never modified.** Whatever you log is read and rendered,
-never written to. A map or a slice you pass to `slog.Any` comes back from
-the logger exactly as you handed it over, even when a group later uses the
-same key.
+**Your values are never modified.** Whatever you log is read and rendered, never
+written to. A map or a slice you pass to `slog.Any` comes back from the logger
+exactly as you handed it over, even when a group later uses the same key.
 
-**Durations are nanoseconds in json, and readable on the console.** The
-json and webhook payloads emit a `slog.Duration` as a number of
-nanoseconds, matching `slog.NewJSONHandler`, so a consumer can compare and
-aggregate the field without parsing it. The console line emits the same
-duration as `3s`, matching `slog.NewTextHandler`, because a person reads
-it.
+**Durations are nanoseconds in json, and readable on the console.** The json and
+webhook payloads emit a `slog.Duration` as a number of nanoseconds, matching
+`slog.NewJSONHandler`, so a consumer can compare and aggregate the field without
+parsing it. The console line emits the same duration as `3s`, matching
+`slog.NewTextHandler`, because a person reads it.
 
-**The json payload is an object, with the consequences an object has.**
-The record's own fields are named `Time`, `Level`, `Message` and `PC`, and
-they own those names: an attribute keyed after one of them is dropped from
-the json and webhook output. A key logged more than once keeps its last
-value there for the same reason, with one exception: when both are
-`slog.Group` values sharing a key, the two groups are merged into one
-object holding the members of both, rather than the second replacing the
-first. Neither the collision nor the merge applies to the console output,
-which is a line of text: every pair appears, in order. If you need a field
-called `message`, pick a key that does not collide - the collision is
-silent.
+**The json payload is an object, with the consequences an object has.** The
+record's own fields are named `Time`, `Level`, `Message` and `PC`, and they own
+those names: an attribute keyed after one of them is dropped from the json and
+webhook output. A key logged more than once keeps its last value there for the
+same reason, with one exception: when both are `slog.Group` values sharing a
+key, the two groups are merged into one object holding the members of both,
+rather than the second replacing the first. Neither the collision nor the merge
+applies to the console output, which is a line of text: every pair appears, in
+order. If you need a field called `message`, pick a key that does not collide -
+the collision is silent.
 
-**Empty things follow the `slog.Handler` contract.** An empty `Attr` is
-ignored, an empty group is elided along with its key, a group with an
-empty key is inlined into its parent, and `WithGroup("")` returns the
-handler unchanged.
+**Empty things follow the `slog.Handler` contract.** An empty `Attr` is ignored,
+an empty group is elided along with its key, a group with an empty key is
+inlined into its parent, and `WithGroup("")` returns the handler unchanged.
 
 ## When delivery fails
 
-Every handler returns an error from `Handle` when it could not deliver
-the record:
+Every handler returns an error from `Handle` when it could not deliver the
+record:
 
--   `ConsoleHandler` and `JSONHandler` return the error from their write to
-    stdout, wrapped, so `errors.Is` still matches the original
--   `WebhookHandler` returns an error when the request fails, and also when
-    the server answers with a status outside 2xx, a redirect included,
-    since it does not follow redirects. A request that has not finished
-    after 5 seconds fails with a timeout error, so a webhook server that
-    never answers holds up a log call for 5 seconds at most
--   `MultiplexHandler`, which simplelog installs as the default, passes the
-    record to every handler it holds even after one of them fails, then
-    returns all their errors joined with `errors.Join` (nil if none failed)
+- `ConsoleHandler` and `JSONHandler` return the error from their write to
+  stdout, wrapped, so `errors.Is` still matches the original
+- `WebhookHandler` returns an error when the request fails, and also when the
+  server answers with a status outside 2xx, a redirect included, since it does
+  not follow redirects. A request that has not finished after 5 seconds fails
+  with a timeout error, so a webhook server that never answers holds up a log
+  call for 5 seconds at most
+- `MultiplexHandler`, which simplelog installs as the default, passes the record
+  to every handler it holds even after one of them fails, then returns all their
+  errors joined with `errors.Join` (nil if none failed)
 
-`slog.Info`, `slog.Error` and the other `slog.Logger` methods throw that
-error away. That is how `log/slog` works, and simplelog cannot change it.
-To find out whether a record was delivered, build a `slog.Record` and pass
-it to the handler yourself, for example
-`slog.Default().Handler().Handle(ctx, record)`, then check the error it
-returns. Console output takes the file and line from the record's `PC`,
-which you set with `runtime.Callers` as the `log/slog` documentation
+`slog.Info`, `slog.Error` and the other `slog.Logger` methods throw that error
+away. That is how `log/slog` works, and simplelog cannot change it. To find out
+whether a record was delivered, build a `slog.Record` and pass it to the handler
+yourself, for example `slog.Default().Handler().Handle(ctx, record)`, then check
+the error it returns. Console output takes the file and line from the record's
+`PC`, which you set with `runtime.Callers` as the `log/slog` documentation
 shows. A record whose `PC` is zero prints `???:0` instead.
 
 ## Entrypoints
@@ -143,8 +136,10 @@ alpine. We provide:
 
 - `script/bootstrap` — install all dependencies (go if missing, goimports with
   `go install` at a pinned commit unless the installed one already reports the
-  pinned version, then `go mod download`); golangci-lint is not installed,
-  since it runs only in Docker
+  pinned version, then `go mod download`; node through nvm at a pinned version
+  if node is missing, yarn at a pinned version if it is missing, then the
+  `prettier` that `package.json` and `yarn.lock` pin); golangci-lint is not
+  installed, since it runs only in Docker
 - `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
@@ -152,23 +147,23 @@ alpine. We provide:
 - `script/test` — run the test suite under the race detector in Docker by
   building only the `test` stage of the `Dockerfile`, without the build cache,
   so every run tests; the image is tagged `simplelog-test`
-- `script/lint` — run golangci-lint in Docker by building only the `lint`
-  stage of the `Dockerfile`, without the build cache, so every run lints; the
-  image is tagged `simplelog-lint`
-- `script/fmt` — format all files (writes) with the goimports that
-  `script/bootstrap` installs
-- `script/fmt-check` — check formatting (read-only); fails if `gofmt -l`
-  reports files
+- `script/lint` — run golangci-lint in Docker by building only the `lint` stage
+  of the `Dockerfile`, without the build cache, so every run lints; the image is
+  tagged `simplelog-lint`
+- `script/fmt` — format all files (writes): Go with the goimports that
+  `script/bootstrap` installs, then every `*.md` file with `prettier`
+- `script/fmt-check` — check formatting (read-only); fails if `gofmt -l` reports
+  files, or if `prettier` would change any `*.md` file
 - `script/check` — run all checks: `test`, `lint`, `fmt-check` (our own
   extension)
-- `script/docker` — build the Docker image without the build cache, tagged
-  via `script/projectname` (byte-identical across repos); it also passes the
-  output of `git describe` as the `VERSION` build argument, which is ignored
-  because this `Dockerfile` does not declare it
-- `script/cibuild` — what CI runs: `script/bootstrap`, then `script/check`,
-  then the same image build as `script/docker` (byte-identical across repos)
-- `script/precommit` — run by the git pre-commit hook (our own extension);
-  runs a `go mod tidy` guard, then `script/check`
+- `script/docker` — build the Docker image without the build cache, tagged via
+  `script/projectname` (byte-identical across repos); it also passes the output
+  of `git describe` as the `VERSION` build argument, which is ignored because
+  this `Dockerfile` does not declare it
+- `script/cibuild` — what CI runs: `script/bootstrap`, then `script/check`, then
+  the same image build as `script/docker` (byte-identical across repos)
+- `script/precommit` — run by the git pre-commit hook (our own extension); runs
+  a `go mod tidy` guard, then `script/check`
 - `script/install-precommit` — installs the git pre-commit hook (our own
   extension); `make hooks` shims to it
 

TODO.md

@@ -1,86 +1,89 @@
 # Workflow
 
-* branch (from `main`)
-* do the work in Next Step
-* move Next Step to the top of Completed Steps
-* move the top item of Future Steps into Next Step
-* commit (`TODO.md` changes in the same commit as the work)
-* merge to `main` if the branch is not protected, otherwise open a PR
-* push
+- branch (from `main`)
+- do the work in Next Step
+- move Next Step to the top of Completed Steps
+- move the top item of Future Steps into Next Step
+- commit (`TODO.md` changes in the same commit as the work)
+- merge to `main` if the branch is not protected, otherwise open a PR
+- push
 
 # Status
 
 1.0+
 
-Tagged v1.0.0 (2024-06-14) and 1.0.1 (2026-02-08). In post-1.0
-maintenance; the library is referenced by the Go styleguide.
+Tagged v1.0.0 (2024-06-14) and 1.0.1 (2026-02-08). In post-1.0 maintenance; the
+library is referenced by the Go styleguide.
 
 # Next Step
 
-Restructure README.md into the standard sections: Description, Getting
-Started, Rationale, Design, TODO, License, Author
+Restructure README.md into the standard sections: Description, Getting Started,
+Rationale, Design, TODO, License, Author
 
 # Completed Steps
 
-* 2026-10-06: re-vendored the standard files from `sneak/prompts` at
-    commit `dd4027b`: `REPO_POLICIES.md`, the CI workflow, `.gitignore`,
-    and `.golangci.yml` together with the lint stage's new image, plus
-    the `.editorconfig` and `.dockerignore` this repo lacked, which
-    finishes the Makefile and policy-files step. `script/cibuild` now
-    bootstraps and runs `script/check` before building the image, the
-    format check runs only on the host, the last `Dockerfile` stage runs
-    `script/bootstrap`, which installs goimports at a pinned commit
-* 2026-10-06: a webhook request now times out after 5 seconds, so a
-    server that never answers no longer stops every log call; the webhook
-    handler also reads each answer to the end so its connection is reused
-* 2026-10-06: the console handler takes the file and line it prints from
-    the record's `PC` instead of counting stack frames, so they name the
-    call site whether the record came through a `slog.Logger` or straight
-    to `Handle`
-* 2026-10-06: the tests run under the race detector, in Docker:
-    `script/test` builds the `test` stage of the `Dockerfile`, which runs
-    `go test -race`, and a new final stage makes a plain `docker build`
-    run both the `lint` and `test` stages
-* 2026-10-06: the linter runs only in Docker: `script/lint` builds the
-    `lint` stage of the `Dockerfile`, every `docker build` in `script/`
-    runs without the build cache, and `script/bootstrap` no longer
-    installs golangci-lint
-* 2026-10-06: every handler now returns a failed delivery from `Handle`
-    instead of discarding it: console and JSON return the stdout write
-    error, the webhook also fails on a non-2xx answer, and the multiplex
-    delivers to every handler and returns their errors joined
-* 2026-08-10: fixed every handler discarding slog attributes: console,
-    JSON and webhook handlers now emit record attributes, accumulate
-    WithAttrs without mutating the receiver, and honour WithGroup;
-    slog.Group values nest and LogValuer values are resolved; console
-    keys and values holding invalid UTF-8 are quoted
-* 2026-08-07: added canonical `.golangci.yml` (v2 schema), pinned the
-    `Dockerfile` lint stage to golangci-lint v2.12.2 (tag+digest), and
-    fixed all findings the v1→v2 jump surfaced without changing any
-    exported signatures or behavior
-- 2026-07-07 Adopted scripts-to-rule-them-all: `script/` entrypoints,
-    Makefile shims, README Entrypoints section
-* 2026-02-08: fixed JSONHandler deadlock from recursive log.Println,
-    with regression test; tagged 1.0.1
-* 2024-06-14: 1.0 prep: lint and fmt enforced in Docker build, call
-    stack depth fix so log locations report correctly, example script,
-    removed non-building RELP code; tagged v1.0.0
-* 2024-05-22: module path moved to sneak.berlin/go/simplelog
-* 2024-05-14: initial library: slog-based console, JSON, webhook, and
-    RELP handlers, MultiplexHandler, caller file/line info, UTC ISO
-    timestamps, level-colored output
+- 2026-10-06: `make fmt` and `make fmt-check` also format Markdown, with
+  `prettier` at the standard settings, pinned through `package.json` and
+  `yarn.lock`; `script/bootstrap` installs node and yarn for it, and the
+  existing Markdown was formatted once
+- 2026-10-06: re-vendored the standard files from `sneak/prompts` at commit
+  `dd4027b`: `REPO_POLICIES.md`, the CI workflow, `.gitignore`, and
+  `.golangci.yml` together with the lint stage's new image, plus the
+  `.editorconfig` and `.dockerignore` this repo lacked, which finishes the
+  Makefile and policy-files step. `script/cibuild` now bootstraps and runs
+  `script/check` before building the image, the format check runs only on the
+  host, the last `Dockerfile` stage runs `script/bootstrap`, which installs
+  goimports at a pinned commit
+- 2026-10-06: a webhook request now times out after 5 seconds, so a server that
+  never answers no longer stops every log call; the webhook handler also reads
+  each answer to the end so its connection is reused
+- 2026-10-06: the console handler takes the file and line it prints from the
+  record's `PC` instead of counting stack frames, so they name the call site
+  whether the record came through a `slog.Logger` or straight to `Handle`
+- 2026-10-06: the tests run under the race detector, in Docker: `script/test`
+  builds the `test` stage of the `Dockerfile`, which runs `go test -race`, and a
+  new final stage makes a plain `docker build` run both the `lint` and `test`
+  stages
+- 2026-10-06: the linter runs only in Docker: `script/lint` builds the `lint`
+  stage of the `Dockerfile`, every `docker build` in `script/` runs without the
+  build cache, and `script/bootstrap` no longer installs golangci-lint
+- 2026-10-06: every handler now returns a failed delivery from `Handle` instead
+  of discarding it: console and JSON return the stdout write error, the webhook
+  also fails on a non-2xx answer, and the multiplex delivers to every handler
+  and returns their errors joined
+- 2026-08-10: fixed every handler discarding slog attributes: console, JSON and
+  webhook handlers now emit record attributes, accumulate WithAttrs without
+  mutating the receiver, and honour WithGroup; slog.Group values nest and
+  LogValuer values are resolved; console keys and values holding invalid UTF-8
+  are quoted
+- 2026-08-07: added canonical `.golangci.yml` (v2 schema), pinned the
+  `Dockerfile` lint stage to golangci-lint v2.12.2 (tag+digest), and fixed all
+  findings the v1→v2 jump surfaced without changing any exported signatures or
+  behavior
+
+* 2026-07-07 Adopted scripts-to-rule-them-all: `script/` entrypoints, Makefile
+  shims, README Entrypoints section
+
+- 2026-02-08: fixed JSONHandler deadlock from recursive log.Println, with
+  regression test; tagged 1.0.1
+- 2024-06-14: 1.0 prep: lint and fmt enforced in Docker build, call stack depth
+  fix so log locations report correctly, example script, removed non-building
+  RELP code; tagged v1.0.0
+- 2024-05-22: module path moved to sneak.berlin/go/simplelog
+- 2024-05-14: initial library: slog-based console, JSON, webhook, and RELP
+  handlers, MultiplexHandler, caller file/line info, UTC ISO timestamps,
+  level-colored output
 
 # Future Steps
 
-* Delete the old plain TODO file once this TODO.md lands
-* Add .aider.* to .gitignore and remove the stray aider artifacts from
-    the working tree
-* Pick one tag scheme before the next release (v1.0.0 vs 1.0.1 are
-    inconsistent)
-* Tag v1.0.2, with the leading v, once the attribute fix lands, so
-    consuming repos can move off pseudo-version pins in one step
-* Fix RELP output to cache (from old TODO)
-* Re-add RELP delivery over TCP to remote rsyslog imrelp; removed
-    2024-06-14 because it did not build (README planned feature)
-* Add regex filtering for webhook logs (from old TODO)
-* Better console output format (from old TODO)
+- Delete the old plain TODO file once this TODO.md lands
+- Add .aider.\* to .gitignore and remove the stray aider artifacts from the
+  working tree
+- Pick one tag scheme before the next release (v1.0.0 vs 1.0.1 are inconsistent)
+- Tag v1.0.2, with the leading v, once the attribute fix lands, so consuming
+  repos can move off pseudo-version pins in one step
+- Fix RELP output to cache (from old TODO)
+- Re-add RELP delivery over TCP to remote rsyslog imrelp; removed 2024-06-14
+  because it did not build (README planned feature)
+- Add regex filtering for webhook logs (from old TODO)
+- Better console output format (from old TODO)

package.json

@@ -0,0 +1,6 @@
+{
+  "private": true,
+  "devDependencies": {
+    "prettier": "3.8.1"
+  }
+}

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 "$@"

yarn.lock

@@ -0,0 +1,8 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+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==