cli-helpers

github.com/strongo/cli-helpers/selfupdate lets a Go CLI update its own binary in place — safely. It decides how the running binary was installed before it touches anything: a package-manager-owned install (Homebrew, Scoop, WinGet) is never overwritten directly. It is redirected to that manager's own upgrade command by default, or can explicitly delegate to structured manager argv; a manual install (a release archive someone unpacked, or a go install target) is downloaded, sha256-verified against the release's own checksums, and swapped in atomically. Everything specific to one CLI — its identity, its managers, its naming conventions, its exit codes — is supplied by the caller. Nothing here is hard-coded to any one consumer.

See spec/features/self-update/README.md for the full behavioral contract this package implements, and cmd/selfupdate/ for a complete, runnable consumer (this module's own reference CLI, which updates itself from this repository's GitHub releases using nothing but the public API below).

Safety guarantees

• A managed install is never overwritten directly. Classify resolves symlinks first (a Homebrew cask shim usually is one) and checks the result against each configured Manager's path markers. A match routes to ActionRedirected unless the consumer explicitly configured an executable and argv. Executable mode confirms and invokes the manager without a shell; it still never downloads or writes the managed binary itself, and it refuses release pins the manager cannot guarantee.
• An unrecognized install is never treated as safe to overwrite. A path that matches neither a manager nor a plausible manual location (go/bin, or directly inside a bin directory) is Ambiguous, not Manual. Ambiguity fails closed.
• The checksum is verified before a single byte is extracted. The downloaded archive's sha256 is compared against that release's own checksums file first; extraction only happens on a match. A mismatch, or a missing checksum entry, aborts with nothing written.
• The replace is atomic. The verified binary is staged to a temp file in the same directory as the target (same filesystem) and moved into place with a single rename. On POSIX that's one atomic rename(2); on Windows, where a running .exe can't be overwritten, the current target is renamed aside first and restored if the final move fails.
• Every failure leaves a working binary. Release lookup, download, checksum, staging, and permission failures all return before any write to the install location. There is no failure mode that ends with a partial or missing executable where the old one used to be.
• A pin fetches that release's own assets, never "latest." The download URL is built from the release's own tag (.../releases/download/<tag>/<asset>), not the /releases/latest/ alias — an older pinned release can't accidentally resolve to whatever is currently newest.

Install

go get github.com/strongo/cli-helpers/selfupdate

Import migration

The package now lives in the github.com/strongo/cli-helpers module. Maintained consumers must replace these imports together:

Previous import	Current import
github.com/strongo/selfupdate	github.com/strongo/cli-helpers/selfupdate
github.com/strongo/selfupdate/cobracmd	github.com/strongo/cli-helpers/selfupdate/cobracmd
github.com/strongo/selfupdate/cliui	github.com/strongo/cli-helpers/selfupdate/cliui

Historical github.com/strongo/selfupdate tags remain available at their published versions. New github.com/strongo/cli-helpers releases use the new module path, so consumers must not request the old path at @latest.

Build a publishable skills snapshot

cmd/skillsbundle is the shared, offline producer for every Strongo CLI and skills plugin. CI resolves a branch or tag to its full commit SHA first, checks out the plugin repository locally, and invokes the producer against that exact committed tree. It never reads uncommitted or ignored checkout files, fetches the network, or accepts a short SHA.

Create a descriptor with plugin identity, repository, source path, full revision, plugin version, and optional CLI compatibility bounds. digest may be omitted; if supplied it must match the committed content. source.version is the plugin's own version, independent of any CLI release tag.

{"plugin":{"publisher":"strongo","name":"example-skills"},"source":{"repository":"github.com/strongo/example-skills","path":"skills","revision":"0123456789012345678901234567890123456789","version":"1.2.3"}}

Run it from a colocated CLI repository or from a separately checked-out plugin repository:

go run github.com/strongo/cli-helpers/cmd/skillsbundle \
  --descriptor ci/skills-bundle.json --repo "$GITHUB_WORKSPACE" --out dist/skills

The fresh output directory contains skillsync-bundle.tar, skillsync-bundle.json, and embed/{bundle.json,content/...}. All come from one captured committed snapshot, preserving tracked dotfiles and executable modes. If origin exists, its normalized repository identity must agree with the descriptor; without one, the tool verifies local Git commit/tree provenance but cannot independently attest the repository name. It never overwrites an existing output path and returns an error rather than claiming publication on a partial failure.

Use all: when embedding the generated directory so tracked dotfiles remain available to the embedded snapshot. The descriptor retains executable paths, because embed.FS does not preserve executable modes.

import "embed"

//go:embed all:generated/skills/embed
var generatedSkills embed.FS

Wiring example

A minimal CLI wires one Config and builds a Cobra command from it:

package cli

import (
	"github.com/spf13/cobra"
	"github.com/strongo/cli-helpers/selfupdate"
	"github.com/strongo/cli-helpers/selfupdate/cobracmd"
)

// version is stamped at link time, e.g. -ldflags "-X your/module.version=v1.2.3".
var version = "dev"

func newSelfUpdateCommand() *cobra.Command {
	cfg := selfupdate.Config{
		BinaryName:     "wb",
		Repository:     "sneat-dev/wb",
		CurrentVersion: version,
		// "dev" is the default undetermined placeholder; only set this when
		// a different one is needed, e.g. a Homebrew-formula build reports
		// "unknown" instead.
		UndeterminedVersions: []string{"unknown"},
		Managers: []selfupdate.Manager{
			selfupdate.Homebrew("brew upgrade --cask wb").
				WithExecutableUpgrade("brew", "upgrade", "--cask", "wb"),
		},
		SupportedPlatforms: []selfupdate.Platform{
			{GOOS: "darwin", GOARCH: "amd64"},
			{GOOS: "darwin", GOARCH: "arm64"},
			{GOOS: "linux", GOARCH: "amd64"},
			{GOOS: "linux", GOARCH: "arm64"},
		},
		VersionProbeArgs: []string{"version", "--json"},
		// AssetName, ChecksumsName, ReleasesAPIURL, DownloadURL, and
		// HTTPClient all default to GoReleaser-shaped conventions against
		// the real GitHub API — set them only to deviate, or (in tests) to
		// point at an httptest.Server.
	}

	return cobracmd.New(cfg, cobracmd.CommandOptions{
		Aliases:    []string{"update"},
		Errors:     wbErrors{}, // maps *selfupdate.Failure onto wb's own exit codes
		JSONFormat: true,
	})
}

// wbErrors implements cobracmd.ErrorMapper for wb's own three-code exit
// contract (0/1/2).
type wbErrors struct{}

func (wbErrors) Failure(err error) error {
	code := 1
	if selfupdate.KindOf(err) == selfupdate.KindPermission {
		code = 2
	}
	return exitError{code: code, err: err}
}

func (wbErrors) UpdateAvailable(res selfupdate.CheckResult) error {
	return exitError{code: 1, err: nil} // folded into wb's general findings code
}

A CLI that doesn't use Cobra calls cfg.Check(ctx) and cfg.Update(ctx, opts) directly — cobracmd is optional sugar over the same two calls; the root package has no command-framework dependency at all. It doesn't have to be hand-rolled from scratch either: github.com/strongo/cli-helpers/selfupdate/cliui holds the same confirmation prompt, non-interactive refusal, and text/JSON writers cobracmd itself is built from, with no Cobra (or any other framework) dependency:

package cli

import (
	"context"
	"os"

	"github.com/strongo/cli-helpers/selfupdate"
	"github.com/strongo/cli-helpers/selfupdate/cliui"
)

func selfUpdate(ctx context.Context, cfg selfupdate.Config, yes bool) error {
	confirm := cliui.Confirm(cliui.ConfirmOptions{
		In:  os.Stdin,
		Out: os.Stdout,
		Yes: yes, // wire from your own --yes/-y flag; nil Interactive -> cliui.IsTerminal
	})

	outcome, err := cfg.Update(ctx, selfupdate.Options{Confirm: confirm})
	if err != nil {
		if selfupdate.KindOf(err) == selfupdate.KindAmbiguous {
			cliui.WriteAmbiguousGuidance(os.Stdout, cfg)
		}
		return err // map to your own exit code however you already do
	}
	cliui.WriteOutcome(os.Stdout, os.Stderr, cfg, outcome)
	return nil
}

cobracmd and cliui implement the exact same behavior — the former is just the Cobra flag/wiring layer on top of the latter — so a Cobra CLI and a hand-rolled one built from cliui directly print byte-identical output for the same Outcome/CheckResult.

Post-update integrations

Options.AfterUpdate is an optional typed callback for work that must run from the installed binary after self-update, such as refreshing a CLI-matched skill bundle. It receives the completed Outcome and an absolute ExecutableIdentity with both the invocation path and its symlink-resolved target. The callback runs only after an update, an already-current result, or a successful executable package-manager update. For package-manager updates the identity is resolved after the manager finishes, so it follows a changed cask or version path.

cobracmd.CommandOptions.AfterUpdate passes the same callback to the core. Callback failures are non-fatal Outcome.AfterUpdateWarning values: text output writes them to stderr and JSON keeps stdout parseable with an after_update_warning field.

Why exit codes and output belong to the host, not this package

Two real consumers of this exact package disagree about what "an update is available" should cost: one reserves a dedicated exit code for it, one folds it into a general findings code alongside everything else. Neither is wrong — it's a property of each CLI's own contract with its scripts and users, not of the update logic. So Config.Check and Config.Update never decide a process exit code and never touch a terminal; they return typed outcomes (Verdict, Action, FailureKind) a caller switches on, and cobracmd's ErrorMapper is exactly the seam where each consumer's own convention plugs in. The alternative — baking one CLI's exit-code opinions into the shared package — is what made the pre-package version of this logic unshippable as a library in the first place: it worked for exactly one CLI.

Dry runs

Options.DryRun walks the entire decision path — detection, target resolution (latest or a pin), the downgrade guard — and stops just before the download would start, returning ActionPlanned with the exact asset URL a real run would fetch (Outcome.PlannedURL). cobracmd exposes this as --dry-run. It's the way to verify a CLI's own wiring — managers, asset naming, platform list — without ever replacing a binary.

Testing your own wiring

Nothing in this package touches the network or the filesystem beyond what a real Update call requires, and every GitHub endpoint, filesystem operation, and TTY check it makes is overridable — see Config.ReleasesAPIURL/ DownloadURL/HTTPClient for pointing at an httptest.Server, and cobracmd.CommandOptions.Interactive for driving the confirmation prompt without a real terminal. The package's own test suite (this repo) exercises every FailureKind, every Manager, and both exit-code-contract shapes this way — see *_test.go for the pattern.