Print the byte unit once in the summary line (closes #17)

formatBytes already ends in a unit, so the summary line read "9 B
bytes" or "1.0 KiB bytes". The format string in Stats.Print no longer
adds the word "bytes".

Print now takes the io.Writer to print to; its callers pass os.Stderr,
and the new test passes a buffer to read the line for one small and
one large byte count.

Model: opus-5-5

.dockerignore

@@ -0,0 +1,63 @@
+# .dockerignore does NOT use .gitignore semantics. Docker matches with
+# moby/patternmatcher: filepath.Match plus `**`, so `*` does not cross
+# `/` and an unprefixed pattern is anchored at the context root. Every
+# depth-independent pattern therefore needs `**/`, or `config/.env` and
+# `certs/server.key` still ship while this file reads as solved. Only
+# genuinely root-anchored entries go unprefixed. Never transplant these
+# into .gitignore, where `**/` is wrong.
+#
+# Matching is case-sensitive, so secrets use character ranges rather
+# than an ALL-CAPS twin, which would still miss `Server.Key`.
+#
+# Extend with this repo's own host-built artifacts, written anchored:
+# `/myapp`, never `**/myapp`, which also matches `cmd/myapp/` and
+# deletes the package directory from the context.
+
+# .git is sent without its config. Without a VERSION build argument the
+# stage that compiles runs `git describe --tags --always` on .git, which
+# does not need .git/config; that file can hold a credential, such as a
+# password in a remote URL or the token the CI checkout step stores there.
+.git/config
+
+# Agent scratch: one full checkout of the repo per in-flight agent.
+# Anchored because it occurs once where agents run at the repo root.
+# KNOWN GAP: a repo running agents in subdirectories still ships
+# `services/api/.claude/` and must add its own anchored entry.
+.claude
+
+# 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`.
+**/*.[eE][nN][vV]
+**/.[eE][nN][vV].*
+**/.[eE][nN][vV][rR][cC]
+
+# Private keys and the bundles carrying them. Public certificates
+# (*.crt, *.cer) are deliberately absent: they are legitimate inputs.
+**/*.[pP][eE][mM]
+**/*.[kK][eE][yY]
+**/*.[pP]12
+**/*.[pP][fF][xX]
+**/[iI][dD]_[rR][sS][aA]
+**/[iI][dD]_[dD][sS][aA]
+**/[iI][dD]_[eE][cC][dD][sS][aA]
+**/[iI][dD]_[eE][dD]25519
+
+# Dependencies: restored inside the image, never copied in.
+**/node_modules
+
+# OS metadata.
+**/.DS_Store
+**/Thumbs.db
+
+# Editor state: never a build input, and it churns COPY.
+**/*.swp
+**/*.swo
+**/*~
+**/*.bak
+**/.idea
+**/.vscode
+**/*.sublime-*
+
+# This repo's host-built binary (`make build`); the image builds its own.
+/attrsum

.gitea/workflows/check.yml

@@ -0,0 +1,13 @@
+name: check
+on: [push]
+jobs:
+    check:
+        runs-on: ubuntu-latest
+        steps:
+            # actions/checkout v4.2.2, 2026-02-28
+            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+              # Full history and tags, so the build stamps the same
+              # `git describe` version as a full clone.
+              with:
+                  fetch-depth: 0
+            - run: script/cibuild

.golangci.yml

@@ -0,0 +1,98 @@
+version: "2"
+
+# Config schema uses the golangci-lint v2 layout (settings live under
+# linters.settings, not top-level linters-settings) so that the
+# thresholds below are actually applied by golangci-lint >= v2.
+
+run:
+  timeout: 5m
+  modules-download-mode: readonly
+
+linters:
+  default: all
+  enable:
+    # Successor to the deprecated gomodguard. Named explicitly, rather than
+    # left to `default: all`, because it carries the module policy below.
+    - gomodguard_v2
+  disable:
+    # Genuinely incompatible with project patterns
+    - exhaustruct      # Requires all struct fields
+    - godot            # Requires comments to end with periods
+    - wrapcheck        # Too verbose for internal packages
+    - varnamelen       # Short names like db, id are idiomatic Go
+    # Deprecated: the warning is attached to the old name, so it is
+    # silenced by disabling that name, not by enabling the successor.
+    - wsl              # Deprecated, replaced by wsl_v5
+    - gomodguard       # Deprecated, replaced by gomodguard_v2
+  settings:
+    lll:
+      line-length: 88
+    funlen:
+      lines: 80
+      statements: 50
+    cyclop:
+      max-complexity: 15
+    dupl:
+      threshold: 100
+    depguard:
+      # Test-support code must not be compiled into the shipped binary. A
+      # test-support package exists to hand a test privileges the program
+      # itself must never have, so a file that is not a test must not import
+      # one. Test files, and the files inside a package whose directory name
+      # ends in `test`, are where that code belongs, and are exempt.
+      #
+      # The deny list below is the one part of this file a repository is
+      # expected to extend, and the only part it may. depguard matches an
+      # import path against a list of prefixes, so it cannot be told "any path
+      # whose last segment ends in test"; a repository's own test-support
+      # packages have to be named here one at a time, by full import path,
+      # under a module path that differs from repository to repository. Add
+      # them; change nothing else.
+      rules:
+        test-support:
+          list-mode: lax
+          files:
+            - "$all"
+            - "!$test"
+            - "!**/*test/**"
+          deny:
+            - pkg: net/http/httptest
+              desc: >-
+                Test-support code belongs in test files and in packages whose
+                directory name ends in test, not in the shipped binary.
+    # Only decisions already recorded in the Go package defaults are
+    # listed here. Every entry matches the module path exactly.
+    gomodguard_v2:
+      blocked:
+        - module: github.com/rs/zerolog
+          recommendations:
+            - log/slog
+          reason: "Structured logging is stdlib log/slog."
+        # One entry per pre-fork module path, because the later releases
+        # are separate paths. A prefix match would be shorter but would
+        # also reach github.com/go-redis/redismock, the test double for
+        # the successor these entries recommend.
+        - module: github.com/go-redis/redis
+          recommendations:
+            - github.com/redis/go-redis/v9
+          reason: "Pre-fork module; use the maintained go-redis v9."
+        - module: github.com/go-redis/redis/v7
+          recommendations:
+            - github.com/redis/go-redis/v9
+          reason: "Pre-fork module; use the maintained go-redis v9."
+        - module: github.com/go-redis/redis/v8
+          recommendations:
+            - github.com/redis/go-redis/v9
+          reason: "Pre-fork module; use the maintained go-redis v9."
+        - module: github.com/sergi/go-diff
+          recommendations:
+            - github.com/aymanbagabas/go-udiff
+          reason: "No unified diff output; use go-udiff."
+        - module: github.com/hexops/gotextdiff
+          recommendations:
+            - github.com/aymanbagabas/go-udiff
+          reason: "Unmaintained fork; use go-udiff."
+
+issues:
+  max-issues-per-linter: 0
+  max-same-issues: 0

Dockerfile

@@ -0,0 +1,66 @@
+# Lint phase
+# golangci/golangci-lint:v2.12.2, 2026-10-05
+FROM golangci/golangci-lint@sha256:5cceeef04e53efe1470638d4b4b4f5ceefd574955ab3941b2d9a68a8c9ad5240 AS lint
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN golangci-lint run --config .golangci.yml ./...
+
+# Test phase. -race needs cgo and so a C compiler, which the Debian Go
+# image ships and the alpine one does not. The tests run as an
+# unprivileged user: root can read a file with mode 0000, so the
+# permission test would fail.
+# golang:1.25.7-trixie, 2026-10-06
+FROM golang@sha256:2b174ffcf56c7ad0c47d30d2630693265639ddf2a5141149c2da34db921791b4 AS test
+RUN useradd --create-home testuser
+USER testuser
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN go test -timeout 90s -race -cover ./... || \
+    { echo "--- Rerunning with -v for details ---"; \
+      go test -timeout 90s -race -v ./...; exit 1; }
+
+# Build stage. Nothing is wanted from either phase above; the copies
+# are what make BuildKit build them first, so this stage cannot run
+# unless lint and test passed.
+# golang 1.25-alpine, 2026-02-28
+FROM golang@sha256:f6751d823c26342f9506c03797d2527668d095b0a15f1862cddb4d927a7a4ced AS builder
+COPY --from=lint /src/go.sum /dev/null
+COPY --from=test /src/go.sum /dev/null
+RUN apk add --no-cache git make
+# A tar-stream context keeps the sender's file owners, which git refuses.
+RUN git config --system --add safe.directory /src
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+
+# The version stamped into the binary: the VERSION build argument when one
+# is given, otherwise `git describe --tags --always` of the .git the build
+# context carries: the tag on a tagged commit, tag-N-gHASH on a commit after
+# one, the short commit when no tag is reachable. A context that carries .git
+# and still yields no version fails the build. With neither, as from a source
+# tarball, the binary reports dev.
+ARG VERSION
+RUN version="${VERSION:-$(git describe --tags --always)}"; \
+    if [ -e .git ] && { [ -z "$version" ] || [ "$version" = dev ] || \
+        [ "$version" = unknown ]; }; then \
+        echo "version is '$version' although .git is present" >&2; \
+        exit 1; \
+    fi; \
+    make build VERSION="${version:-dev}"
+
+# Runtime stage
+# alpine 3.21, 2026-02-28
+FROM alpine@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709
+
+RUN apk add --no-cache ca-certificates tzdata
+
+WORKDIR /app
+
+COPY --from=builder /src/attrsum /app/attrsum
+
+ENTRYPOINT ["/app/attrsum"]

Makefile

@@ -1,24 +1,64 @@
-TESTDIR := $(HOME)/Documents/_SYSADMIN/cyberdyne
+.PHONY: default bootstrap setup test lint fmt fmt-check check docker hooks build clean try
 
-default: test
+# The version `make build` stamps into the binary: the git tag or short
+# commit, -dirty with uncommitted changes. `make build VERSION=x` stamps x,
+# which is how the Dockerfile passes its version in.
+VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo dev)
+
+# Standard targets are thin shims; the implementations live in script/
+# per the scripts-to-rule-them-all pattern.
+
+default: check build
+
+bootstrap:
+	@script/bootstrap
+
+setup:
+	@script/setup
 
 test:
-	@go test ./... -v
+	@script/test
+
+lint:
+	@script/lint
+
+fmt:
+	@script/fmt
+
+fmt-check:
+	@script/fmt-check
+
+check:
+	@script/check
+
+docker:
+	@script/docker
+
+hooks:
+	@script/install-precommit
 
 build: clean
-	@go build .
+	@go build -ldflags "-X main.Version=$(VERSION)" .
 
 clean:
 	@rm -f attrsum
 
+# Runs the binary on three small files in a new temporary directory, which
+# the trap removes when the recipe ends, also when a step fails. The check
+# after clear is expected to fail, so its exit status is ignored.
 try: build
-	./attrsum sum add -v $(TESTDIR)
-	./attrsum check -v $(TESTDIR)
-	./attrsum clear -v $(TESTDIR)
-	-./attrsum check -v $(TESTDIR)
-	./attrsum sum add -v $(TESTDIR)
-	./attrsum check -v $(TESTDIR)
-	touch $(TESTDIR)/*
-	./attrsum sum update -v $(TESTDIR)
-	./attrsum check -v $(TESTDIR)
-
+	@set -ex; \
+	dir=$$(mktemp -d); \
+	trap 'rm -rf "$$dir"' EXIT; \
+	echo one >"$$dir/a"; \
+	echo two >"$$dir/b"; \
+	echo three >"$$dir/c"; \
+	./attrsum sum add -v "$$dir"; \
+	./attrsum check -v "$$dir"; \
+	./attrsum clear -v "$$dir"; \
+	./attrsum check -v "$$dir" || true; \
+	./attrsum sum add -v "$$dir"; \
+	./attrsum check -v "$$dir"; \
+	touch "$$dir"/*; \
+	./attrsum sum update -v "$$dir"; \
+	./attrsum check -v "$$dir"

README.md

@@ -31,52 +31,73 @@ Semantic Versioning 2.0.0 is used for tags.
 ## Usage
 
 ```bash
-# add checksum & timestamp xattrs to every regular file under DIR
-attrsum sum add DIR
+# add checksum & timestamp xattrs to every regular file under one or more paths
+attrsum sum add DIR1 DIR2 file.txt
 
 # update checksum only when file mtime is newer than stored sumtime
-attrsum sum update DIR
+attrsum sum update DIR1 DIR2
 
 # verify checksums, stop on first error
-attrsum check DIR
+attrsum check DIR1 DIR2
 
 # verify every file, reporting each result, keep going after errors
-attrsum -v check --continue DIR
+attrsum -v check --continue DIR1 DIR2
 
 # remove checksum & timestamp xattrs
-attrsum clear DIR
+attrsum clear DIR1 DIR2
+
+# read paths from stdin (use - as argument)
+find /data -name "*.jpg" | attrsum sum add -
+
+# quiet mode (suppress progress bar and summary)
+attrsum -q sum add DIR
 ```
 
 | xattr key                                   | meaning                        |
 |---------------------------------------------|--------------------------------|
-| `berlin.sneak.app.attrsum.checksum`         | base-58 multihash (sha2-256)   |
-| `berlin.sneak.app.attrsum.sumtime`          | RFC 3339 timestamp of checksum |
+| `user.berlin.sneak.app.attrsum.checksum`    | base-58 multihash (sha2-256)   |
+| `user.berlin.sneak.app.attrsum.sumtime`     | RFC 3339 timestamp of checksum |
 
 Flags:
 
 * `-v, --verbose` — per-file log output
+* `-q, --quiet` — suppress all output except errors (no progress bar or summary)
 * `--exclude PATTERN` — skip paths matching rsync/Doublestar glob
 * `--exclude-dotfiles` — skip any path component that starts with `.`
 
+All commands display a progress bar with ETA and print a summary report to stderr on completion (unless `--quiet` is specified).
+
 `attrsum` **never follows symlinks** and skips non-regular files (sockets, devices, …).
 
 ---
 
 ## Why?
 
-Apple APFS and Linux ext3/ext4 **store no per-file metadata checksums**, so
-silent data corruption can pass unnoticed.  `attrsum` keeps a portable,
-tamper-evident checksum **inside each file’s xattrs**, providing integrity
+Apple APFS and Linux ext3/ext4 **store no per-file content checksums**, so
+silent data corruption can pass unnoticed.  `attrsum` keeps a portable checksum **inside each file’s xattrs**, providing integrity
 verification that travels with the file itself—no external database
 required.  Now you can trust a USB stick didn't eat your data.
 
 ---
 
+## TODO
+
+Future improvements under consideration:
+
+- **Dry-run mode (`--dry-run`, `-n`)** — show what would be done without making changes
+- **JSON output (`--json`)** — machine-readable output for scripting and integration
+- **Parallel processing (`-j N`)** — use multiple goroutines for faster checksumming on large trees
+- **Exit code documentation** — formalize and document exit codes for scripting
+
+---
+
 ## Contributing
 
 * Author & maintainer: **sneak** – <sneak@sneak.berlin>
 * Issues / PRs: <https://git.eeqj.de/sneak/attrsum/>
-* Code must pass `go vet`, `go test ./...`, and `go fmt`.
+* Code must pass `make check`, which runs the tests and golangci-lint as
+  phases of the `Dockerfile` (Docker is required) and checks formatting
+  with `gofmt`.
 * No CLA; contributions are under WTFPL v2.
 
 ---

TODO.md

@@ -0,0 +1,76 @@
+# 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
+
+# Status
+
+1.0+
+
+Tagged 1.0.0 (2025-05-08). Substantial correctness fixes and features
+have landed since the tag.
+
+# Next Step
+
+Re-vendor the canonical files from `sneak/prompts` at `dd4027b`
+(https://git.eeqj.de/sneak/attrsum/issues/13): add `REPO_POLICIES.md`
+and `.editorconfig`, refresh `.gitignore` (only the `attrsum` binary
+today), `.dockerignore`, `.gitea/workflows/check.yml` and
+`.golangci.yml`, and move the lint phase to golangci-lint v2.14.0.
+
+# Completed Steps
+
+* 2026-10-06: the summary line after `sum`, `check` and `clear` prints
+    the byte unit once (`1.5 KiB`, not `1.5 KiB bytes`)
+* 2026-10-06: lint and test run as phases of the `Dockerfile`, and the
+    build stage depends on both; `script/lint` and `script/test` each
+    build their phase with `--no-cache`; `script/cibuild` bootstraps,
+    runs `script/check`, then builds the image; golangci-lint is no
+    longer installed on the host
+* 2026-10-06: `check --continue` keeps going past a file or directory
+    it cannot read: it counts it as failed, prints the error and the
+    path on stderr, and checks the rest of the tree
+* 2026-10-05: golangci-lint settings take effect: canonical
+    `.golangci.yml` (v2 layout, settings under `linters.settings`),
+    golangci-lint pinned at v2.12.2 in `Dockerfile` and
+    `script/bootstrap`, and the code fixed for what the settings now
+    report (long lines in `attrsum.go` rewrapped)
+* 2026-10-05: `make try` runs on three small files in a temporary
+    directory that it removes afterwards, also when a step fails,
+    instead of on a fixed directory on one person's machine
+* 2026-10-02: `attrsum --version` reports the git tag or short commit,
+    stamped by `make build` and by a plain `docker build .` of a clone;
+    `.dockerignore` sends `.git` without `.git/config` and keeps a
+    host-built `attrsum` out; CI checks out full history so it stamps
+    the same version
+* 2026-02-02: correctness pass: track actual bytes read instead of
+    stale file size, atomic failure tracking in ProcessCheck, detect
+    file modification during checksum (TOCTOU), propagate countFiles
+    errors, single progress bar across paths, error on empty stdin,
+    dead code removal
+* 2026-02-01: added quiet mode, progress bar, summary report, and stdin
+    path input; multiple file/directory arguments for all commands
+* 2025-07-12: README update
+* 2025-05-08: initial working tool with passing tests, skips
+    non-regular files, Makefile, README; tagged 1.0.0
+
+# Future Steps
+
+* Restructure README.md into the standard sections: Description,
+    Getting Started, Entrypoints, Rationale, Design, TODO, License,
+    Author (Getting Started, Why?, TODO, License exist; Description,
+    Entrypoints, Design, Author are missing)
+* Add a `LICENSE` file matching the README's WTFPL v2; sneak's to add,
+    not an agent's
+* Tag a patch release to ship the 2026-02-02 correctness fixes
+* Dry-run mode (--dry-run, -n): show what would be done without making
+    changes (from README TODO)
+* JSON output (--json) for scripting and integration (from README TODO)
+* Parallel processing (-j N) with multiple goroutines for faster
+    checksumming on large trees (from README TODO)
+* Formalize and document exit codes for scripting (from README TODO)

attrsum_test.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"bytes"
+	"errors"
 	"os"
 	"path/filepath"
 	"strings"
@@ -10,49 +12,106 @@ import (
 	"github.com/pkg/xattr"
 )
 
-func skipIfNoXattr(t *testing.T, path string) {
-	if err := xattr.Set(path, "user.test", []byte("1")); err != nil {
-		t.Skipf("skipping: xattr not supported: %v", err)
-	} else {
-		_ = xattr.Remove(path, "user.test")
+const (
+	dirPerm  = 0o755
+	filePerm = 0o644
+	noPerm   = 0o000
+
+	// futureSkew advances a file's mtime far enough to be unambiguously
+	// newer than a previously recorded sumtime.
+	futureSkew = 2 * time.Second
+)
+
+// skipIfNoXattr skips the test unless the filesystem under dir supports the
+// extended-attribute namespace the program actually uses. Probing with the
+// real checksumKey (rather than a user.* key) matters on Linux, where regular
+// files only accept xattrs in the user.* namespace and the program's
+// berlin.sneak.* keys yield "operation not supported".
+func skipIfNoXattr(t *testing.T, dir string) {
+	t.Helper()
+
+	probe := filepath.Join(dir, "xattr-probe")
+
+	err := os.WriteFile(probe, []byte("probe"), filePerm)
+	if err != nil {
+		t.Fatalf("write probe file: %v", err)
 	}
+
+	defer func() { _ = os.Remove(probe) }()
+
+	err = xattr.Set(probe, checksumKey, []byte("1"))
+	if err != nil {
+		t.Skipf("skipping: xattr namespace %q not supported: %v", checksumKey, err)
+
+		return
+	}
+
+	_ = xattr.Remove(probe, checksumKey)
 }
 
 func writeFile(t *testing.T, root, name, content string) string {
 	t.Helper()
+
 	p := filepath.Join(root, name)
-	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
+
+	err := os.MkdirAll(filepath.Dir(p), dirPerm)
+	if err != nil {
 		t.Fatalf("mkdir: %v", err)
 	}
-	if err := os.WriteFile(p, []byte(content), 0o644); err != nil {
+
+	err = os.WriteFile(p, []byte(content), filePerm)
+	if err != nil {
 		t.Fatalf("write: %v", err)
 	}
+
 	return p
 }
 
+func newTestStats() *Stats {
+	return &Stats{StartTime: time.Now()}
+}
+
 func TestSumAddAndUpdate(t *testing.T) {
+	t.Parallel()
+
+	opts := &options{}
 	dir := t.TempDir()
 	skipIfNoXattr(t, dir)
 
 	f := writeFile(t, dir, "a.txt", "hello")
 
-	if err := ProcessSumAdd(dir); err != nil {
+	err := processSumAdd(opts, dir, newTestStats(), nil)
+	if err != nil {
 		t.Fatalf("add: %v", err)
 	}
-	if _, err := xattr.Get(f, checksumKey); err != nil {
+
+	_, err = xattr.Get(f, checksumKey)
+	if err != nil {
 		t.Fatalf("checksum missing: %v", err)
 	}
+
 	tsb, _ := xattr.Get(f, sumTimeKey)
 	origTime, _ := time.Parse(time.RFC3339Nano, string(tsb))
 
-	os.WriteFile(f, []byte(strings.ToUpper("hello")), 0o644)
-	now := time.Now().Add(2 * time.Second)
-	os.Chtimes(f, now, now)
+	err = os.WriteFile(f, []byte(strings.ToUpper("hello")), filePerm)
+	if err != nil {
+		t.Fatalf("rewrite: %v", err)
+	}
 
-	if err := ProcessSumUpdate(dir); err != nil {
+	now := time.Now().Add(futureSkew)
+
+	err = os.Chtimes(f, now, now)
+	if err != nil {
+		t.Fatalf("chtimes: %v", err)
+	}
+
+	err = processSumUpdate(opts, dir, newTestStats(), nil)
+	if err != nil {
 		t.Fatalf("update: %v", err)
 	}
+
 	tsb2, _ := xattr.Get(f, sumTimeKey)
+
 	newTime, _ := time.Parse(time.RFC3339Nano, string(tsb2))
 	if !newTime.After(origTime) {
 		t.Fatalf("sumtime not updated")
@@ -60,46 +119,74 @@ func TestSumAddAndUpdate(t *testing.T) {
 }
 
 func TestProcessCheckIntegration(t *testing.T) {
+	t.Parallel()
+
+	opts := &options{}
 	dir := t.TempDir()
 	skipIfNoXattr(t, dir)
 
 	writeFile(t, dir, "b.txt", "world")
-	if err := ProcessSumAdd(dir); err != nil {
+
+	err := processSumAdd(opts, dir, newTestStats(), nil)
+	if err != nil {
 		t.Fatalf("add: %v", err)
 	}
-	if err := ProcessCheck(dir, false); err != nil {
+
+	err = processCheck(opts, dir, false, newTestStats(), nil)
+	if err != nil {
 		t.Fatalf("check ok: %v", err)
 	}
 
 	f := filepath.Join(dir, "b.txt")
-	os.WriteFile(f, []byte("corrupt"), 0o644)
 
-	if err := ProcessCheck(dir, false); err == nil {
+	err = os.WriteFile(f, []byte("corrupt"), filePerm)
+	if err != nil {
+		t.Fatalf("corrupt: %v", err)
+	}
+
+	err = processCheck(opts, dir, false, newTestStats(), nil)
+	if err == nil {
 		t.Fatalf("expected mismatch error, got nil")
 	}
 }
 
 func TestClearRemovesAttrs(t *testing.T) {
+	t.Parallel()
+
+	opts := &options{}
 	dir := t.TempDir()
 	skipIfNoXattr(t, dir)
 
 	f := writeFile(t, dir, "c.txt", "data")
-	if err := ProcessSumAdd(dir); err != nil {
+
+	err := processSumAdd(opts, dir, newTestStats(), nil)
+	if err != nil {
 		t.Fatalf("add: %v", err)
 	}
 
-	if err := ProcessClear(dir); err != nil {
+	err = processClear(opts, dir, newTestStats(), nil)
+	if err != nil {
 		t.Fatalf("clear: %v", err)
 	}
-	if _, err := xattr.Get(f, checksumKey); err == nil {
+
+	_, err = xattr.Get(f, checksumKey)
+	if err == nil {
 		t.Fatalf("checksum still present after clear")
 	}
-	if _, err := xattr.Get(f, sumTimeKey); err == nil {
+
+	_, err = xattr.Get(f, sumTimeKey)
+	if err == nil {
 		t.Fatalf("sumtime still present after clear")
 	}
 }
 
 func TestExcludeDotfilesAndPatterns(t *testing.T) {
+	t.Parallel()
+
+	opts := &options{
+		excludeDotfiles: true,
+		excludePatterns: []string{"*.me"},
+	}
 	dir := t.TempDir()
 	skipIfNoXattr(t, dir)
 
@@ -107,61 +194,162 @@ func TestExcludeDotfilesAndPatterns(t *testing.T) {
 	keep := writeFile(t, dir, "keep.txt", "keep")
 	skip := writeFile(t, dir, "skip.me", "skip")
 
-	oldDot := excludeDotfiles
-	oldPat := excludePatterns
-	excludeDotfiles = true
-	excludePatterns = []string{"*.me"}
-	defer func() { excludeDotfiles, excludePatterns = oldDot, oldPat }()
-
-	if err := ProcessSumAdd(dir); err != nil {
+	err := processSumAdd(opts, dir, newTestStats(), nil)
+	if err != nil {
 		t.Fatalf("add with excludes: %v", err)
 	}
 
-	if _, err := xattr.Get(keep, checksumKey); err != nil {
+	_, err = xattr.Get(keep, checksumKey)
+	if err != nil {
 		t.Fatalf("expected xattr on keep.txt: %v", err)
 	}
-	if _, err := xattr.Get(hidden, checksumKey); err == nil {
+
+	_, err = xattr.Get(hidden, checksumKey)
+	if err == nil {
 		t.Fatalf(".hidden should have been excluded")
 	}
-	if _, err := xattr.Get(skip, checksumKey); err == nil {
+
+	_, err = xattr.Get(skip, checksumKey)
+	if err == nil {
 		t.Fatalf("skip.me should have been excluded")
 	}
 }
 
 func TestSkipBrokenSymlink(t *testing.T) {
+	t.Parallel()
+
+	opts := &options{}
 	dir := t.TempDir()
 	skipIfNoXattr(t, dir)
 
-	// Create a dangling symlink
+	// Create a dangling symlink.
 	link := filepath.Join(dir, "dangling.lnk")
-	if err := os.Symlink(filepath.Join(dir, "nonexistent.txt"), link); err != nil {
+
+	err := os.Symlink(filepath.Join(dir, "nonexistent.txt"), link)
+	if err != nil {
 		t.Fatalf("symlink: %v", err)
 	}
 
-	// Should not error and should not create xattrs on link
-	if err := ProcessSumAdd(dir); err != nil {
-		t.Fatalf("ProcessSumAdd with symlink: %v", err)
+	// Should not error and should not create xattrs on link.
+	err = processSumAdd(opts, dir, newTestStats(), nil)
+	if err != nil {
+		t.Fatalf("processSumAdd with symlink: %v", err)
 	}
-	if _, err := xattr.Get(link, checksumKey); err == nil {
+
+	_, err = xattr.Get(link, checksumKey)
+	if err == nil {
 		t.Fatalf("symlink should not have xattr")
 	}
 }
 
 func TestPermissionErrors(t *testing.T) {
+	t.Parallel()
+
+	opts := &options{}
 	dir := t.TempDir()
 	skipIfNoXattr(t, dir)
 
 	secret := writeFile(t, dir, "secret.txt", "data")
-	os.Chmod(secret, 0o000)
-	defer os.Chmod(secret, 0o644)
 
-	if err := ProcessSumAdd(dir); err == nil {
+	err := os.Chmod(secret, noPerm)
+	if err != nil {
+		t.Fatalf("chmod: %v", err)
+	}
+
+	defer func() { _ = os.Chmod(secret, filePerm) }()
+
+	err = processSumAdd(opts, dir, newTestStats(), nil)
+	if err == nil {
 		t.Fatalf("expected permission error, got nil")
 	}
-	if err := ProcessSumUpdate(dir); err == nil {
+
+	err = processSumUpdate(opts, dir, newTestStats(), nil)
+	if err == nil {
 		t.Fatalf("expected permission error on update, got nil")
 	}
-	if err := ProcessCheck(dir, false); err == nil {
+
+	err = processCheck(opts, dir, false, newTestStats(), nil)
+	if err == nil {
 		t.Fatalf("expected permission error on check, got nil")
 	}
 }
+
+func TestCheckContinuePastUnreadable(t *testing.T) {
+	t.Parallel()
+
+	opts := &options{}
+	dir := t.TempDir()
+	skipIfNoXattr(t, dir)
+
+	writeFile(t, dir, "a.txt", "one")
+	secret := writeFile(t, dir, "b.txt", "two")
+	writeFile(t, dir, "c/d.txt", "three")
+	writeFile(t, dir, "e.txt", "four")
+
+	err := processSumAdd(opts, dir, newTestStats(), nil)
+	if err != nil {
+		t.Fatalf("add: %v", err)
+	}
+
+	// An unreadable file and an unlistable directory sit between the
+	// readable files a.txt and e.txt.
+	sub := filepath.Join(dir, "c")
+
+	err = os.Chmod(secret, noPerm)
+	if err != nil {
+		t.Fatalf("chmod file: %v", err)
+	}
+
+	defer func() { _ = os.Chmod(secret, filePerm) }()
+
+	err = os.Chmod(sub, noPerm)
+	if err != nil {
+		t.Fatalf("chmod dir: %v", err)
+	}
+
+	defer func() { _ = os.Chmod(sub, dirPerm) }()
+
+	stats := newTestStats()
+
+	err = processCheck(opts, dir, true, stats, nil)
+	if !errors.Is(err, errVerification) {
+		t.Fatalf("expected verification error, got %v", err)
+	}
+
+	if stats.FilesProcessed != 2 || stats.FilesFailed != 2 {
+		t.Fatalf("expected 2 verified and 2 failed, got %d and %d",
+			stats.FilesProcessed, stats.FilesFailed)
+	}
+
+	// Without --quiet, runCheck counts the files for the progress bar
+	// before it checks any, so the count reaches the unlistable directory
+	// first.
+	err = runCheck(opts, []string{dir}, true)
+	if !errors.Is(err, errVerification) {
+		t.Fatalf("expected verification error from runCheck, got %v", err)
+	}
+}
+
+func TestSummaryPrintsByteUnitOnce(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		bytesProcessed int64
+		want           string
+	}{
+		{9, ", 9 B in "},
+		{1536, ", 1.5 KiB in "},
+	}
+
+	for _, tt := range tests {
+		var out bytes.Buffer
+
+		stats := newTestStats()
+		stats.BytesProcessed = tt.bytesProcessed
+		stats.Print(&out, &options{}, "check")
+
+		if !strings.Contains(out.String(), tt.want) {
+			t.Errorf("summary %q does not contain %q", out.String(), tt.want)
+		}
+	}
+}

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/mr-tron/base58 v1.2.0
 	github.com/multiformats/go-multihash v0.2.3
 	github.com/pkg/xattr v0.4.10
+	github.com/schollz/progressbar/v3 v3.19.0
 	github.com/spf13/cobra v1.9.1
 )
 
@@ -14,10 +15,13 @@ require (
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/klauspost/cpuid/v2 v2.0.9 // indirect
 	github.com/minio/sha256-simd v1.0.0 // indirect
+	github.com/mitchellh/colorstring v0.0.0-20190213212951-d06e56a500db // indirect
 	github.com/multiformats/go-varint v0.0.6 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/spaolacci/murmur3 v1.1.0 // indirect
 	github.com/spf13/pflag v1.0.6 // indirect
 	golang.org/x/crypto v0.0.0-20220525230936-793ad666bf5e // indirect
-	golang.org/x/sys v0.1.0 // indirect
+	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/term v0.28.0 // indirect
 	lukechampine.com/blake3 v1.1.6 // indirect
 )

go.sum

@@ -1,13 +1,21 @@
 github.com/bmatcuk/doublestar/v4 v4.8.1 h1:54Bopc5c2cAvhLRAzqOGCYHYyhcDHsFF4wWIR5wKP38=
 github.com/bmatcuk/doublestar/v4 v4.8.1/go.mod h1:xBQ8jztBU6kakFMg+8WGxn0c6z1fTSPVIjEY1Wr7jzc=
+github.com/chengxilo/virtualterm v1.0.4 h1:Z6IpERbRVlfB8WkOmtbHiDbBANU7cimRIof7mk9/PwM=
+github.com/chengxilo/virtualterm v1.0.4/go.mod h1:DyxxBZz/x1iqJjFxTFcr6/x+jSpqN0iwWCOK1q10rlY=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/klauspost/cpuid/v2 v2.0.4/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
 github.com/klauspost/cpuid/v2 v2.0.9 h1:lgaqFMSdTdQYdZ04uHyN2d/eKdOMyi2YLSvlQIBFYa4=
 github.com/klauspost/cpuid/v2 v2.0.9/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
+github.com/mattn/go-runewidth v0.0.16 h1:E5ScNMtiwvlvB5paMFdw9p4kSQzbXFikJ5SQO6TULQc=
+github.com/mattn/go-runewidth v0.0.16/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
 github.com/minio/sha256-simd v1.0.0 h1:v1ta+49hkWZyvaKwrQB8elexRqm6Y0aMLjCNsrYxo6g=
 github.com/minio/sha256-simd v1.0.0/go.mod h1:OuYzVNI5vcoYIAmbIvHPl3N3jUzVedXbKy5RFepssQM=
+github.com/mitchellh/colorstring v0.0.0-20190213212951-d06e56a500db h1:62I3jR2EmQ4l5rM/4FEfDWcRD+abF5XlKShorW5LRoQ=
+github.com/mitchellh/colorstring v0.0.0-20190213212951-d06e56a500db/go.mod h1:l0dey0ia/Uv7NcFFVbCLtqEBQbrT4OCwCSKTEv6enCw=
 github.com/mr-tron/base58 v1.2.0 h1:T/HDJBh4ZCPbU39/+c3rRvE0uKBQlU27+QI8LJ4t64o=
 github.com/mr-tron/base58 v1.2.0/go.mod h1:BinMc/sQntlIE1frQmRFPUoPA1Zkr8VRgBdjWI2mNwc=
 github.com/multiformats/go-multihash v0.2.3 h1:7Lyc8XfX/IY2jWb/gI7JP+o7JEq9hOa7BFvVU9RSh+U=
@@ -16,19 +24,30 @@ github.com/multiformats/go-varint v0.0.6 h1:gk85QWKxh3TazbLxED/NlDVv8+q+ReFJk7Y2
 github.com/multiformats/go-varint v0.0.6/go.mod h1:3Ls8CIEsrijN6+B7PbrXRPxHRPuXSrVKRY101jdMZYE=
 github.com/pkg/xattr v0.4.10 h1:Qe0mtiNFHQZ296vRgUjRCoPHPqH7VdTOrZx3g0T+pGA=
 github.com/pkg/xattr v0.4.10/go.mod h1:di8WF84zAKk8jzR1UBTEWh9AUlIZZ7M/JNt8e9B6ktU=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
+github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/schollz/progressbar/v3 v3.19.0 h1:Ea18xuIRQXLAUidVDox3AbwfUhD0/1IvohyTutOIFoc=
+github.com/schollz/progressbar/v3 v3.19.0/go.mod h1:IsO3lpbaGuzh8zIMzgY3+J8l4C8GjO0Y9S69eFvNsec=
 github.com/spaolacci/murmur3 v1.1.0 h1:7c1g84S4BPRrfL5Xrdp6fOJ206sU9y293DDHaoy0bLI=
 github.com/spaolacci/murmur3 v1.1.0/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
 github.com/spf13/cobra v1.9.1 h1:CXSaggrXdbHK9CF+8ywj8Amf7PBRmPCOJugH954Nnlo=
 github.com/spf13/cobra v1.9.1/go.mod h1:nDyEzZ8ogv936Cinf6g1RU9MRY64Ir93oCnqb9wxYW0=
 github.com/spf13/pflag v1.0.6 h1:jFzHGLGAlb3ruxLB8MhbI6A8+AQX/2eW4qeyNZXNp2o=
 github.com/spf13/pflag v1.0.6/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 golang.org/x/crypto v0.0.0-20220525230936-793ad666bf5e h1:T8NU3HyQ8ClP4SEE+KbFlg6n0NhuTsN4MyznaarGsZM=
 golang.org/x/crypto v0.0.0-20220525230936-793ad666bf5e/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/sys v0.0.0-20220408201424-a24fb2fb8a0f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.1.0 h1:kunALQeHf1/185U1i0GOB/fy1IPRDDpuoOOqRReG57U=
-golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.29.0 h1:TPYlXGxvx1MGTn2GiZDhnjPA9wZzZeGKHHmKhHYvgaU=
+golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/term v0.28.0 h1:/Ts8HFuMR2E6IP/jlo7QVLZHggjKQbhu/7H0LJFr3Gg=
+golang.org/x/term v0.28.0/go.mod h1:Sw/lC2IAUZ92udQNf3WodGtn4k/XoLyZoh8v/8uiwek=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 lukechampine.com/blake3 v1.1.6 h1:H3cROdztr7RCfoaTpGZFQsrqvweFLrqS73j7L7cmR5c=
 lukechampine.com/blake3 v1.1.6/go.mod h1:tkKEOtDkNtklkXtLNEOGNq5tcV90tJiA1vAA12R78LA=

script/bootstrap

@@ -0,0 +1,80 @@
+#!/bin/sh
+# 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.
+# goimports is installed via `go install` at a pinned commit (never
+# "latest"). The linter is not installed: it runs only as the lint phase
+# of the Dockerfile.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+# Pinned versions, 2026-10-05
+# goimports v0.42.0
+GOIMPORTS_REF="golang.org/x/tools/cmd/goimports@009367f5c17a8d4c45a961a3a509277190a9a6f0"
+
+PKGMGR=""
+SUDO=""
+APT_UPDATED=""
+
+detect_pkgmgr() {
+    [ -n "$PKGMGR" ] && return 0
+    if command -v nix-env >/dev/null 2>&1; then
+        PKGMGR="nix"
+    elif command -v apt-get >/dev/null 2>&1; then
+        PKGMGR="apt"
+    elif command -v brew >/dev/null 2>&1; then
+        PKGMGR="brew"
+    elif command -v apk >/dev/null 2>&1; then
+        PKGMGR="apk"
+    else
+        echo "bootstrap: no supported package manager (nix, apt, brew, apk)" >&2
+        exit 1
+    fi
+    if [ "$PKGMGR" = "apt" ]; then
+        export DEBIAN_FRONTEND=noninteractive
+        if [ "$(id -u)" != "0" ]; then
+            SUDO="sudo"
+        fi
+    fi
+}
+
+# pkg_install <nix-attr> <apt-pkg> <brew-formula> <apk-pkg>
+pkg_install() {
+    detect_pkgmgr
+    case "$PKGMGR" in
+        nix) nix-env -iA "nixpkgs.$1" ;;
+        apt)
+            if [ -z "$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
+}
+
+missing() {
+    ! command -v "$1" >/dev/null 2>&1
+}
+
+main() {
+    cd "$ROOT"
+
+    if missing git; then pkg_install git git git git; fi
+    if missing make; then pkg_install gnumake make make make; fi
+    if missing go; then pkg_install go golang go go; fi
+
+    # Format tool, pinned via go install (installs into
+    # "$(go env GOPATH)/bin"; ensure that is on your PATH).
+    if missing goimports; then go install "$GOIMPORTS_REF"; fi
+
+    go mod download
+
+    echo "bootstrap complete"
+}
+
+main "$@"

script/check

@@ -0,0 +1,16 @@
+#!/bin/sh
+# script/check: run all checks (test, lint, fmt-check). Our own
+# extension to scripts-to-rule-them-all. test and lint are Docker
+# phases; fmt-check is native, because a formatter writes the working
+# tree. Must not modify any files.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+
+main() {
+    "$SCRIPT_DIR/test"
+    "$SCRIPT_DIR/lint"
+    "$SCRIPT_DIR/fmt-check"
+}
+
+main "$@"

script/cibuild

@@ -0,0 +1,28 @@
+#!/bin/sh
+# 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.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
+
+main() {
+    cd "$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.
+    version="$(git describe --tags --always --dirty 2>/dev/null || true)"
+    [ -n "$version" ] || version="unknown"
+    docker build --no-cache \
+        --build-arg VERSION="$version" \
+        -t "$("$SCRIPT_DIR/projectname")" .
+}
+
+main "$@"

script/docker

@@ -0,0 +1,24 @@
+#!/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.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(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.
+    version="$(git describe --tags --always --dirty 2>/dev/null || true)"
+    [ -n "$version" ] || version="unknown"
+    docker build --no-cache \
+        --build-arg VERSION="$version" \
+        -t "$("$SCRIPT_DIR/projectname")" .
+}
+
+main "$@"

script/fmt

@@ -0,0 +1,13 @@
+#!/bin/sh
+# script/fmt: format all files (writes).
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    gofmt -s -w .
+    goimports -w .
+}
+
+main "$@"

script/fmt-check

@@ -0,0 +1,18 @@
+#!/bin/sh
+# script/fmt-check: check formatting (read-only). Same scope as
+# script/fmt, but fails instead of writing.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    files="$(gofmt -l .)"
+    if [ -n "$files" ]; then
+        echo "gofmt: files not formatted:" >&2
+        echo "$files" >&2
+        exit 1
+    fi
+}
+
+main "$@"

script/install-precommit

@@ -0,0 +1,16 @@
+#!/bin/sh
+# script/install-precommit: install the git pre-commit hook that runs
+# script/precommit. Our own extension to scripts-to-rule-them-all.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    hook=".git/hooks/pre-commit"
+    printf '#!/bin/sh\nset -e\nscript/precommit\n' > "$hook"
+    chmod +x "$hook"
+    echo "pre-commit hook installed: runs script/precommit"
+}
+
+main "$@"

script/lint

@@ -0,0 +1,23 @@
+#!/bin/sh
+# script/lint: run the linter. Linting is a phase of the Dockerfile and
+# this builds that phase alone; the linter is never installed or run on
+# a developer host, where a shared result cache and a host-global lock
+# 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.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    docker build --no-cache \
+        --target lint \
+        -t "$("$SCRIPT_DIR/projectname")-lint" .
+}
+
+main "$@"

script/precommit

@@ -0,0 +1,21 @@
+#!/bin/sh
+# script/precommit: run by the git pre-commit hook; fails the commit if
+# checks fail. Our own extension to scripts-to-rule-them-all. Go extra:
+# go mod tidy must be a no-op before the checks run.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    go mod tidy
+    if ! git diff --exit-code -- go.mod go.sum; then
+        echo "precommit: go mod tidy changed go.mod/go.sum;" \
+            "stage the changes and retry" >&2
+        exit 1
+    fi
+    "$SCRIPT_DIR/check"
+}
+
+main "$@"

script/projectname

@@ -0,0 +1,12 @@
+#!/bin/sh
+# script/projectname: output the name of this project. Our own
+# extension to scripts-to-rule-them-all. Other scripts that need the
+# name (e.g. script/docker) call this, so they can stay identical
+# across all repos.
+set -eu
+
+main() {
+    echo "attrsum"
+}
+
+main "$@"

script/setup

@@ -0,0 +1,13 @@
+#!/bin/sh
+# script/setup: set up the repo for development after a fresh clone:
+# installs dependencies and the git pre-commit hook.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+
+main() {
+    "$SCRIPT_DIR/bootstrap"
+    "$SCRIPT_DIR/install-precommit"
+}
+
+main "$@"

script/test

@@ -0,0 +1,19 @@
+#!/bin/sh
+# 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.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    docker build --no-cache \
+        --target test \
+        -t "$("$SCRIPT_DIR/projectname")-test" .
+}
+
+main "$@"